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After a quake hits, children are required to stay in school until an adult comes to collect them, in case their homes are damaged or their family members aren't available to look after them.

As a result television footage from school and offices in Tokyo during Friday's quake showed workers and students behaving with extraordinary calm and composure as buildings shook violently, sending files tumbling from desks and books from shelves.

After the quake crocodiles of children could be seen in Tokyo walking calmly to muster points wearing their protective helmets.

Many lessons were learned from the Kobe earthquake of 1995 that killed 6,400 people and forced a reassessment of the building regulations for both residential offices and transport infrastructure.

Damage to buildings in Tokyo was slight as a result of Japan's stringent building regulations that ensure that skyscrapers sway in during a quake, but don't collapse.

Buildings are made earthquake proof with the aid of deep foundation and massive shock absorbers that dampen seismic energy. Another method allows the base of a building to move semi-independently to its superstructure, reducing the shaking caused by a quake.

Photographs from the Kobe earthquake showed old buildings collapsed alongside modern buildings that withstood the quake, in some cases canted at an angle, but still standing, after the ground beneath them liquefied.

Immediately after an earthquake strikes in Japan, all television and radio stations switch immediately to official earthquake coverage which informs the public of risks, including tsunamis to enable people to retreat to higher ground or, on the coast, purpose-built tsunami defence bunkers.

For those trapped, all offices and many private houses in Japan have an earthquake emergency kits, including dry rations, drinking water, basic medical supplies. Offices and school also keep hard-hats and gloves for use in the event of a quake.

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Japan earthquake: country better prepared than anyone for quakes and tsunamis

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After a quake hits, children are required to stay in school until an adult comes to collect them, in case their homes are damaged or their family members aren't available to look after them.

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Japan's massive earthquake has sparked a tsunami which has caused further devastation. But what can be done to tsunami-proof a country?
It is a terrifying illustration of man's vulnerability to nature, and the tsunami that has struck the Japanese coast illustrates the difficulty, even for a prosperous nation, of preparing for such an onslaught.

Dr Tiziana Rossetto, a reader in earthquake engineering at University College London, says there is much that contingency planners can do to minimise damage and loss of life.

Precautions include designing buildings to withstand the impact of the waves as well as developing early-warning systems, public education programmes and evacuation strategies, Dr Rossetto adds.

But she warns: "How helpful an early warning system depends on how far away the tsunami strikes - if it's close by, it's not going to be very effective."

Confronted with an unstoppable force like a tsunami - the massive waves created by events like underwater earthquakes - the best course of action is to ensure that members of the public get inland and to higher ground as quickly as possible.

The answer

Totally preventing tsunami-damage is impossible

But an early warning system can allow evacuations and other precautions

Buildings can be constructed to survive the wave with repairable damage

Sophisticated international warning systems mean impending tsunamis can be picked up by sensors. Countries can use radio and television broadcasts as well as loudspeaker networks to alert the public.

However, Dr Rossetto says that if, as in the case of the Japanese tsunami, the earthquake occurs very close to the coast, the authorities may only have five or 10 minutes to warn people.

As a result, countries like Japan have highly-developed public information campaigns to ensure that as many citizens as possible know what to do, using school lessons, television and radio broadcasts and leaflet campaigns.

Likewise, Hawaii has street signage indicating the quickest routes to higher, safer, ground in the event of an emergency.

Evacuating a city may not always be possible if the time-frame is tight, so people may be directed to the top floors of buildings or multi-storey car parks.

In Japan, authorities have tested vertical elevation structures - essentially, tall platforms that people can get onto to lift them above the likely height of any tsunami.

Sensitive buildings like nuclear power plants will be sited as far away from the coast as is possible and designed to shut down into "safe mode" as soon as an earthquake is detected.

Additionally, Dr Rossetto says, sea barriers are sometime put up around strategic areas like harbours and ports - but their effectiveness is not particularly well-established.

Evacuation is not an easy option on many low-lying islands.

In places where people can be got to safety structural engineering can do much to minimise the aftermath.

Dr Gopal Madabhushi, from Cambridge University's engineering department, co-authored a study on tsunami-resistant designs for houses after the 2004 disaster that devastated coastal areas in Indonesia, Thailand, Sri Lanka and elsewhere.

Testing a design from a group of architects at Harvard University, researchers used a large wave tank and found that allowing water through was better than trying to stop it.

"Instead of trying to obstruct the wave, you allow the wave to pass through the structure while causing minimum damage. Large doorways and windows offer a clear path to go through."

The goal of the design is to protect the building and make it easier to reconstruct afterwards, on the assumption that the occupants have fled to higher ground. Destroyed doors and windows are easy to replace.

"Internal doorways are aligned rather than staggered. If you have staggered doors, the wave gets 'locked' into the house."

Houses on piles are one answer, but might not be desirable in all regions for practical reasons.

"Hawaii has traditionally built reinforced concrete buildings - they might leave the ground floor clear like a parking bay, effectively like a building on stilts," says Dr Madabhushi.

WHO, WHAT, WHY?

A part of BBC News Magazine, Who, What, Why? aims to answer questions behind the headlines

Another key facet in building design is making sure load-bearing walls are not hit head on by the wave, causing the collapse of the structure.

"You can see which direction any tsunami would come from, it is easy to make the load-bearing walls perpendicular to that direction."

Not all buildings will be so well-designed, however, warns Dr Adrian Chandler, an earthquake engineer at UCL's Hazard Research Centre.

"For your average residential structure, it's down to the owner as to whether they're going to put these preparations into place," he says.

"In many cases the costs will be excessive."

Indeed, Dr Chandler adds, the only way to be free of the risks associated with a tsunami is not to live near the coast in the first place.

It is advice that has been heeded in the past. After the Hawaiian city of Hilo was hit by successive tsunamis in 1946 and 1960, authorities moved its residents further inland.

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What can you do to tsunami-proof a country?

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Japan's massive earthquake has sparked a tsunami which has caused further devastation. But what can be done to tsunami-proof a country? It is a terrifying illustration of man's vulnerability to nature, and the tsunami that has struck the Japanese coast illustrates the difficulty, even for a prosperous nation, of preparing for such an onslaught.

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Moment Magnitude Explained—What Happened to the Richter Scale?

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Find out how the UK will respond to opportunities and challenges, what is being achieved for the UK and who we are working with.

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In the second of our of blogs on life in the Bay of Naples, we look at how Vesuvius is monitored for signs of activity and what would happen if it were to erupt.
Vesuvius is the most monitored volcano in the world, which is hardly surprising when you consider that there are around 3 million people living within 20 miles (32km) of the crater. Due to the close proximity of such a large population, it is widely considered to be the most dangerous volcano on the planet.

There is currently no smoke or lava being produced, though when I visited the crater rim I could clearly see small fumaroles emitting steam produced by the heat inside the rocks causing rainwater and the remains of the winter snow to evaporate. The threat of a significant event is ever-present however, and the authorities conduct thorough monitoring of the activity around Vesuvius as well as drawing up an emergency response plan should a major eruption occur.

The monitoring of Vesuvius is widespread and takes many forms. Sensors and instruments on the volcano itself detect seismic activity and gas emissions whilst satellite imagery is also used. The volcano is constantly monitored 24 hours a day, 365 days a year from the observatory on the volcano itself, whilst there are also remote locations which can provide full assistance in the event of a major incident requiring evacuation of the on-site observatory. It used to be possible to visit the observatory, but it has been closed since early 2014 for renovation - there is currently no news on its re-opening.

The emergency response plan has several stages. The first stage, having identified an immediate threat, is to evacuate all residents of the 'red zone'. This is an area of approximately 200km 2 around the crater which would bear the brunt of any eruption - around 18 small towns and villages lie in the red zone, with a combined population of around 600,000 people. A complete evacuation is expected to take around 72 hours.

The second phase involves the evacuations of residents from the 'yellow zone' if there was a danger to them from the gas and ash emitted by the eruption. The yellow zone is much larger and comprises the regions of Naples, Salerno, Avellino and Benevento and an additional population of around 2.5 million people. There is also a plan for an area designated the 'blue zone', a small region which falls within the yellow zone but is at an increased risk of flooding.

An evacuation would be ordered following early signs of a major eruption. Each of the 18 regions in the red zone has been twinned with a region of Italy to which their residents would relocate - for example, residents of Pompeii would be moved to and accommodated in the region of Liguria in Italy's north.

However, many experts have condemned the plan as undeliverable and inadequate. For starters, they say that the plan is based on a repeat of the 1631 sub-Plinian eruption of Vesuvius which followed a series of smaller events in the days and weeks prior to the main event. This would allow the authorities time to monitor the increasing activity and prepare for an evacuation before sounding the alarm. Yet the 79AD eruption which devastated Pompeii was a sudden Plinian eruption and a repeat of this type of explosive eruption would render the plan useless.

Evidence from the 79AD suggests that the eruption occurred without warning. The lava flow swept down the volcano's slopes at over 100 miles per hour, destroying everything in its path and leaving people unable to flee. Unfortunately, the lava flows aren't the biggest threat as experts have likened a large-scale Plinian eruption to that of a bomb bigger than the most powerful nuclear weapon being detonated. The effects of this will be a wave of intense heat burning everything in its path, smoke and hot ash being ejected miles into the atmosphere and rocks being flung up to 12 miles away and the creation of a small tsunami in the Bay of Naples.

Even if the authorities are given fair warning, local residents are unlikely to be well-prepared. The authorities don't promote or widely distribute information on safety or the evacuation plan and generally, people haven't prepared by doing simple things such as packing an emergency bag or planning alternative evacuation routes to safety.

Volcano (or earthquake) safety isn't even taught in schools - compare this to somewhere like Japan, where even the smallest of children know to seek shelter under a doorway or table in the event of an earthquake. One person I spoke to said that in the 20 years she'd lived in the area there had been just one practice evacuation held at a local school and that the local emergency services had all been present and ready at the beginning of the simulation - highly unlikely in the actual event!

The same person had been on a local train some years previously, which had stopped due to an electrical fault. After a lengthy delay the doors were opened and instructions given for people to make their way off the train in a calm and orderly manner. Instead she described to me a scene of utter chaos as passengers frantically shoved and pushed each other out of the way as they all scrambled to try and be first out, leaving the less mobile or strong people behind to fend for themselves. Her concern is that in the event of an eruption the residents, unprepared or trained for what to do, would simply panic.

As discussed in our first blog, many people have built illegally in the red zone. Unfortunately, rather than act to remove them by law, the government imposed a series of 'fines' for those who had built without the necessary permits but allowed them to remain. This created a situation whereby there are large populations living in the most dangerous areas of the volcano, in houses which are often not built to the usual standards and therefore are at greater risk of collapse in the event of even low-level seismic or volcanic activity.

To further compound the issue, the roads within the red zone are largely rural - steep, narrow, twisty roads linking small villages and farms - and unfit for the purpose of allowing 600,000 people to flee quickly. Emergency services trying to provide support would be stranded on the same congested roads as the fleeing population.

In the face of pressure from volcanologists, in 1995 the Italian government created the National Park of Vesuvius to increase restrictions in developments within the park boundary, whilst in the early 21 st century the government introduced an offer of funding of around €30,000 to actively encourage people to move away. However, despite their best attempts they have had relatively little impact - €30,000 is not a lot of money with which to buy a new home and, despite the National Park restrictions, new buildings continue to be erected in the red zone.

This short-sighted planning is not unique to Vesuvius. I spoke to a teacher who lives in the town of Sarno, on the south-eastern side of Vesuvius. The Bourbons, who ruled the Kingdom of Naples in the 18 th century, recognised the threat of potential flooding caused by sudden downpours of rain onto the mountains behind the town. They built a series of underground canals and reservoirs to provide protection and conducted surveys which recommended avoiding building in certain areas. Over time these surveys were forgotten about and the town spread over a larger area, resulting in many of the old canals and reservoirs being filled in, blocked or built over.

Sadly, in 1998 Sarno was hit by several large mudslides which partially destroyed the town and killed 137 people. Interestingly, none of the original Bourbon buildings in the old town had been affected whilst there was widespread damage in the areas which they had warned against developing. However, as part of the major re-construction which has taken place in the intervening years, many people have again ignored the advice of the Bourbons, and the lessons of 1998, and re-built their homes in the same high-risk areas.

It seems, much like the locals' attitude towards life in general, the authorities are focussing more on quick-fix solutions than the long-term implications. However, would having a much more sustainable approach to building in the red zone and devising a more robust emergency response plan, accompanied by the necessary training and provision of public information, actually offer any more support and safety to the local population? The evidence suggests perhaps not.

We know that Vesuvius is overdue a large eruption. This may happen tomorrow or it may not happen for another 100 years or more, but the consensus of opinion suggests that that there will be a 'big one' soon. But what will the likely effects of a big eruption be?

To provide some context to how 'big' a big eruption might be, the Eyjafjallajokull eruption which seriously affected European air traffic in 2010 was rated as a scale 4 eruption on the logarithmic Volcanic Explosion Index (VEI). The 79AD eruption of Vesuvius was a scale 5 eruption, making it 10 times as powerful.

We know that the smoke and ash from a big eruption will be ejected high into the atmosphere, where it is extremely likely to cause significant interference to weather patterns across Europe and widespread disruption to global air transportation.

(There is historic evidence of scale 6+ volcanic eruptions causing global changes: the sheer volume of ash and smoke causes skies to darken, resulting in lower global temperatures as a result of less sunlight reaching the earth. This has been known to affect harvest and even prompt mass migration of people.)

Whether or not there are early warning signs enabling the evacuation plan to be put into place, a major eruption of Vesuvius will lead to a large loss of life and the creation of a great number of refugees, with estimates ranging from tens of thousands to millions, depending on the severity of the event.

A final - and not insignificant question - regards the authorities' decision-making process in ordering an evacuation. As previously discussed, a speedy evacuation as a response to an immediate threat would be impossible. But, even given warning of an imminent threat from the volcano, they still face a very difficult decision. Evacuating the area too soon based on a risk that doesn't materialise would devastate the local economy and communities, whilst delaying too long would put the lives of hundreds of thousands, or even millions of people at risk.
In the next of our blogs about the Bay of Naples region, we focus on tourism - how has it changed over the years, what are the impacts on the locals and what does the future hold?

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How is Vesuvius monitored for activity and what emergency plans are in place? - Educational Visits Blog

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In the second of our of blogs on life in the Bay of Naples, we look at how Vesuvius is monitored for signs of activity and what would happen if it were to erupt. Vesuvius is the most monitored volcano in the world, which is hardly surprising when you consider that there are around 3 million people living within 20 miles (32km) of the crater.

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If you are a volcanologist, nothing strikes fear into your heart as much as thinking about the next Vesuvius eruption. This Italian giant is nestled in the sprawling metropolitan area of Naples, population 3.1 million. We're not talking "nearby" like Rainier is to Seattle or Popocatépetl to Mexico City. We're talking a volcano smack in the middle of the city. It is merely ~12 km (~7.5 miles) from the summit craters at Vesuvius to downtown Naples.

For your average pyroclastic flow from a volcano like Vesuvius, that is a trip that would take only about two and a half minutes. We've been lucky so far, as the growth of Naples since World War II has all occurred while Vesuvius has been quiet- its last eruption was in 1944 -but planning needs to be done now for the eruption that will come in the future.

We can be sure that Vesuvius hasn't gone down for the count. Looking back over the last few thousand years, which for a volcano is a very short period of time, Vesuvius has had 42 eruptions that rank as VEI 3 or larger. On that Volcano Explosivity Index, VEI 3 means that over 10,000,000 cubic meters (2.9 billion gallons!) of volcanic ash and debris erupted.

That's not all. Vesuvius has gone even bigger. The eruption in 1631 was VEI 5, which is on the scale of the 1980 eruption of Mount St. Helens or 2011's Puyehue-Cordon Caulle eruption in Chile/Argentina. Both of those comparison eruptions happened in fairly unpopulated areas. But plop something that emits at least a cubic kilometer (over 350 billion cubic feet!) of volcanic ash and debris in the middle of an urban area ... it is really something we haven't seen in modern history.

This is why volcanic hazard planning is so vital to cities on volcanoes. Imagine a scenario where an earthquake swarm and small explosions start happening at Vesuvius, both signs that a larger eruption is in the works. How do you start deciding who to evacuate? An exclusion zone of 5 kilometers from the volcano means an evacuation of ~17,000 people. That is a lot but not wholly untenable.

Now, let's say the explosions start getting more and more vigorous: Vesuvius might be headed to a big eruption. Expand that exclusion zone to 10 kilometers from the crater and we are know looking at evacuating over 675,000 people. A really big eruption will blanket ash in an area tens to hundreds of kilometers from Vesuvius, impacting a population that is ~6 million people.

That would be 6 million people who could lose access to power, water and transportation if Vesuvius unleashes an eruption like was seen in 79 A.D. or 1631. How long would they have to stay away from their homes and livelihoods to be safe? As we've seen around volcanoes like Merapi and Sinabung in Indonesia, it could be years to ... forever. If parts of the Naples area are buried by volcanic material during an eruption, they could be uninhabitable for decades as that loose volcanic debris gets washed down the slopes of Vesuvius during every rainstorm, as like what happened around Pinatubo after its 1991 eruption.

So, much like Seattle and the Pacific Northwest need to prepare for the unthinkable earthquake, Naples and Italy need to prepare for the unthinkable eruption from Vesuvius. They have been getting ready with plans and research on how the region could be impacted, what is the likelihood of a massive eruption and how effective current mitigation plans might be.

However, it is communication of these risks that will make the difference. People need to know what different signs of volcanic unrest mean and in particular, what do geologists mean what we say that an eruption "may occur". Getting people on the ground ready through education, emergency kits, plans for evacuation routes and shelters is vitally important, but if the population doesn't understand how and when to evacuation, you end up with catastrophes like Armero or L'Aquila.

The thing is, comparing preparedness for earthquake and eruptions is difficult. Sure, they are broadly similar: have a plan, have supplies, be ready at a moment's notice. However, for an earthquake, you never know when the Big One might strike and likely, you will never know until it happens. Eruptions, on the other hand, have precursors, but those precursors are a bit of a mixed blessing. Sure, they let you know that a volcano is getting restless and an eruption might happen, but the devil is in the details.

Unrest might mean eruption, but it also might mean nothing but unrest. It also might mean months and months of unrest that lead to something small. In the realm of predicting a volcanic eruption, for every Pinatubo where volcanologists nailed it, there is a Long Valley where nothing happened. (Actually, these days volcanologists are much better, so maybe 3 Pinatubos for every Long Valley). It's like living waiting for a hurricane when it gets windy and rainy, but you're not sure if it will make landfall tomorrow or in 6 months.

The question of when to evacuate is one of the biggest challenges for volcanic disaster mitigation. Call for an evacuation too soon and nothing happens, you lose the public's trust. Wait too long, and you lose the public, literally. The window to get it right can be small when you need the public's help to make for an effective and safe evacuation.

With the millions of people who would need to evacuate during a large eruption from Vesuvius, would such an evacuation even be possible? We tend to think of large-scale and long-term evacuations as things that happen in developing countries, where poor farmers and villagers have to go live in tents: the prototypical refugee camps. An eruption of Vesuvius would require evacuation and temporary shelter on a scale almost unseen in the developed world.

Using the hurricane example again, the largest evacuation in U.S. history was for Hurricane Rita in 2005, when over 3 million people where evacuated from a wide swath of Texas and Louisiana, the majority coming from the Houston metro area. However, this was a temporary evacuation for most people who could head back in a few days after the storm passed. The evacuation of New Orleans for Katrina was "only" in the hundreds of thousands, but might be more similar to a volcanic disaster, where many were not able to return for months to years (if ever).

In both cases, the the Interstate System in U.S. allowed for these mass exoduses from major cities, but still ran into problems of congestion. In Italy, there isn't such a network of large roads to accommodate all that traffic of people fleeing. Even in the face of a potentially lethal eruption, some people will stay behind beyond the warning given by the government. People don't like to leave their homes (just ask Harry Truman).

Remember, it was only 5 years ago when a little volcano in Iceland named Eyjafjallajökull erupted and plunged Europe into chaos because a bunch of people missed their flights. Imagine what could happen if all the Naples had to be evacuated in the face of a restless Vesuvius for months or years?

By some estimates, a large eruption of Vesuvius could kill over 10,000 people, but if a long-term evacuation happens, that number could climb from disease related to housing in temporary shelters. The hit to the Italian economy could be over $20 billion ... and that's likely a low-end estimate that doesn't include the cost of shelter for the potentially millions of volcanic refugees.

So, does this mean it's hopeless? Hardly! Here's what needs to be done to have Naples (or any large city near a volcano) ready for the next big eruption:

Volcano monitoring: This means both having sufficient instruments to measure all the rumbling and burping of the volcano but more importantly, people who are trained to interpret the signals.

Mitigation: Planning needs to be done now for the disaster that may never come in our lifetime. The plan needs to be clear and easy to follow as it is passed on to new people as the years go by. It also needs to be constantly revised as new information becomes available and the city itself changes.

Communication: The scientists need to communicate effectively and clearly to the public about the threat the volcano poses and what different scientific observations mean in terms of eruption. Trust needs to be maintained between the scientists, planners, emergency managers and the public - and communication is the key to that trust.

Practice: Plans are good, but practice and drills are better. A great example of this is Rabaul in Papua New Guinea, where practice saved lives during a full blown eruption of the caldera.

Volcanoes are dangerous. Volcanoes are deadly. But they're also beautiful and awe-inspiring. Being prepared for that next eruption is the key from making the world's most dangerous volcano into the deadliest.

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The World's Most Dangerous Volcano May Kill Another City

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If you are a volcanologist, nothing strikes fear into your heart as much as thinking about the next Vesuvius eruption. This Italian giant is nestled in the sprawling metropolitan area of Naples, population 3.1 million. We're not talking "nearby" like Rainier is to Seattle or Popocatépetl to Mexico City.

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2001 Vesuvius Emergency Plan (updated in 2007)
Dangerous zones Alert levels What happens in case of an ongoing eruption Plan evolution NATIONAL EMERGENCY PLAN
The national emergency plan to protect the inhabitants from a possible eruption of the Vesuvius area has as its baseline the explosive event of 1631.

Drafted by the scientific community has identified three areas with different hazard defined: the red zone, yellow zone and the blue zone. It 'important to note that the eruption of Vesuvius will not be sudden but will be preceded by a series of precursory phenomena already identified some time before as monitored by the Naples section of the National Institute of Geophysics and Volcanology-INGV, which controls the state the volcano 24 hours 24.

The national contingency plan, based on the expected precursory phenomena, identifies four levels of alert following: base, attention, warning, alarm, which correspond to subsequent operational steps, which mark the times of civil protection measures to secure the population and territory.

The whole red area is evacuated, moving to safe areas, the population of the 18 municipalities.

Red Zone. The red zone is the area immediately surrounding the volcano, and is in greater danger as potentially subject to invasion by pyroclastic flows, or mixtures of gases and solids at high temperature which, sliding along the slopes of the volcano at high speed can destroy in a short time everything is on its way. Pyroclastic flows probably will not grow at 360 ° in the neighborhood of the volcano, but will head in one or more preferential directions, it is not possible to know beforehand what the areas actually affected by the flow. The speed with which they develop these phenomena associated with their destructive potential, but does not wait for the start of the eruption to implement preventive measures. Therefore, the National Emergency Plan provides that the red area is completely evacuated before the eruption. The red zone comprises 18 municipalities with a total of about 200kmq extension and just under 550mila population.

Yellow Zone. The yellow zone has a less dangerous than the red and corresponds to the entire area that could be affected by the fallout of pyroclastic particles - ash and lapilli - which may, inter alia, provide a disproportionate burden on the roofs of buildings to determine collapse. The fallout of particles may also cause respiratory problems, particularly in susceptible individuals are not adequately protected, damage to crops and problems to air traffic, rail and road.

It is expected that, as happened in 1631, only 10% of the yellow zone will actually be affected by the fallout particles, suffering damage. Again, however, is not possible to know beforehand what the area actually affected, as will depend on the height of the eruption column and direction and wind speed at high altitude at the time of the eruption. Unlike the red zone, however, the phenomena expected in the yellow zone do not constitute an immediate danger to the population and must spend a certain amount of time before the fallen material to accumulate on roofs of buildings to cause any failure structures.

Therefore, there is the possibility of waiting for the beginning of the eruption to see what the affected area and proceed, if necessary, evacuation of the population that resides there. The yellow zone affects the provinces of Naples, Avellino, Benevento and Salerno.

The Blue Zone. The Blue Zone falls within the yellow zone, but is subject to an agent of further danger. Corresponds to the "valley of Nola," which, for its hydrogeological characteristics, may be subject to floods and floods as well as the fallout of ash and lapilli.

Basic level. The base rate is the current one: a state of activity characterized by the absence of ground deformation, low seismicity, lack of significant changes in the gravity field, constant values ??of temperature and composition of fumarolic gases.

Phase of attention. Upon the occurrence of significant changes in physical and chemical parameters of the volcano, Vesuvius Observatory is expected to inform the Civil Protection Department, which consulted the top experts of the sector from the National Commission for the prediction and prevention of major risks, establishes 'eventual transition to the stage of attention. At this stage the management of any action is entrusted to the Relief Coordination Centre (CCS), established at the Prefecture of Naples.

The variations observed at this stage, however, are not necessarily indicative of the approach of an eruption, and all could easily return to normal, so there is no direct involvement of the population. In any case, the mayors of the municipalities concerned are supported to start its logistics and provide information to the population.

Pre-alert phase. If there is another variation of controlled parameters, you would enter the stage of early warning. In this phase, the operational control passes to the national level, is declared a state of emergency, appoint a Deputy Commissioner, called the Operating Committee of Civil Protection. The police and rescuers are positioned on the territory according to established plans.

At this stage the population is also involved: those who want to leave can do so safely, without fear of leaving their homes unattended, as it is already active supervision of a garrison. Residents of areas at risk can reach their own autonomous systems. However, they follow the instructions of the Emergency Plan of the municipality itself - prepared in accordance with the national plan - as regards the means of removal to be followed in order to allow easier flow of traffic and avoid obstruction to the rescuers. They must also communicate their decision to the Mayor and the data of the locality where they are going to settle.

The area is gradually being manned by rescuers. Health facilities are evacuated in advance of the population are in fact needed more time to plan and regulate the safety of residents and persons in need of assistance.

At this stage you start, and measures for the protection of cultural heritage: to secure the population is a priority, but it is also important to secure and protect the priceless Beniculturali transportable to the extent possible, cultural property. At this stage, if the Commission Major Hazards in the light of developments, believes that the activity of the volcano came back below the pre-alert phase, the Civil Protection Department says the return to the stage of attention.

Alarm stage. If the phenomenon were to continue to increase, you would enter the stage of alarm. This means that experts say now almost certain the eruption, which could occur over several weeks. The alarm is triggered when, in fact, a few weeks before the eruption. The whole red area is evacuated and the population of 18 municipalities moved to safe areas. Already active in the territory will be the Mixed Operations Centers (Com) under the National Plan of emergency, to coordinate activities at the local level.

In this phase, ensure removal of the entire population from the red zone. The Plan provides that the maximum time of 72 hours, the 600 thousand inhabitants in the red zone to be moved, according to the specific instructions contained in the individual municipal plans. The public can obtain its own autonomous system of first asylum or areas outside the zone at risk - structures identified by the region of Campania and its neighboring regions, using his own car or public transport by road provided by the civil protection. We use transport routes and the "gates" of access to the main roads in the established emergency plan. Trains and ships are used as strategic resources to handle any critical phase of implementation of the plan and possible further influx of rescuers. Removal along the main areas are set up information and outreach - information point - where citizens can find information and any logistical support and health.

Each of the 18 municipalities of the Vesuvian region is twinned with an Italian MEP to host the population of the red zone in the long term. After the safety of the citizens of the red zone in the areas of first asylum, we proceed with cars, buses and trains to transfer to the twinned region.

Upon completion of the evacuation, rescue workers also fold in the yellow zone, while the police have a safety belt on the border of the red zone. Again, if the situation were to fall, the Civil Protection Department said after-care phase alarm to return to pre-alert phase.

On the contrary, the eruption took place, the red area is already completely cleared. The inhabitants of the area of the yellow zone affected by the fallout particles are temporarily housed in shelters in the Campania region, while the scientific community is constantly monitoring the evolution of the eruption until it is finished. Once the eruptive activity are carrying out the necessary dell'agibilità structures and damage to the affected areas and can then start over, where possible, the return of the population previously removed.

As we have seen, the waiting period between registration of the first eruption precursory phenomena and the eruption of the evacuation itself could last for months. Civil protection, right from the outset and throughout the emergency, promptly and timely inform the public about what is happening and simultaneously put in place all necessary measures and actions necessary to safeguard life and property in areas at risk.
TWINNINGS
As mentioned, the inhabitants of the red zone should be removed before the eruption. Of course, in Campania, there would be able to accommodate 600 thousand people, therefore, also to enable the maintenance of social relationships and continuity of school activities, each of the 18 municipalities in the red zone is twinned with a region that, in case of eruption, it the host population. The heads of families who are moving away from its own resources and the families who benefited from resources made available, therefore, be reunited twin places already provided by the National Plan of emergency.

Here are the twinnings of the plan: S. Giorgio a Cremano - Lazio; Portici - Emilia Romagna; Ercolano - Tuscany, San Sebastiano al Vesuvio - Molise; Pollena Trocchia - Umbria, Massa di Somma - Umbria, Ottaviano - Piemonte and Valle D'Aosta, Anastasia - Marche; Cercola - Friuli Venezia Giulia, San Giuseppe Vesuviano - Lombardy Terzigno - Veneto Boscoreale - Puglia, Pompei - Liguria; Torre del Greco - Sicily Torre Annunziata - Calabria Trecase - Basilicata; Boscotrecase - Basilicata.
WHAT HAPPENS IN CASE OF AN ONGOING ERUPTION
The population of the red zone is all outside the area at risk and the area affected by potentially destructive phenomena completely evacuated.

The yellow zone is exposed to risk of relapse of ash and lapilli: It is not possible to identify in advance the area actually involved. The area around the volcano is divided into 16 sectors: for each is shown the probability that the wind direction will bring you the deposit of relapse. The chances are highest for people in areas east of the volcano, under the direction of dispersion of fallout deposits of the historical eruptions of Vesuvius.

Approximately 10-15% of the population will actually be interested depending on the direction of prevailing winds. It will, therefore, an operational strategy for variable removal and receipt for the population concerned. The operations will take place during the event in progress with the acceptance of fixed structures in the same region of Campania. The duration of the phenomena is, in fact, limited to a short time, and cause local damage, albeit important. This is why it is not necessary or appropriate to remove outside the region the population of the yellow zone.

Also for the Blue Zone strategy provides for the expulsion of the population at current event. In fact, mudflows, caused by the drag function of ash from rainwater are to be expected during the current event, once you will earn enough volcanic deposit, but even then, and cause serious problems for the movement of people and vehicles. May be particularly vulnerable settlements, industrial and handicraft at the foot of slopes where the slope has allowed for the accumulation of considerable amounts of ash.

The plan is constantly updated to reflect advances in scientific knowledge, but also the continuous change of the urban and the population density of one of the most populated areas of the world. The main objective of the Plan is to safeguard the lives of people living on its slopes. More than 550,000 people live in the highly urbanized area.

The greater the knowledge of how to behave, paths to follow and places to be achieved by the people involved in emergency, the greater will be the evolution of the plan to a more streamlined organizational form of relief.

The commission process since 1991 and update the emergency planning in the Vesuvius area are established by the Department of Civil Protection.

Plan updating phases
1991 First Commission - guidelines for evaluation the risk of eruption in the Vesuvius area

1993 Second Commission - National Emergency Plan for the Vesuvius Area

1995 First version of the National Emergency Plan

2001 First Update of the Plan

2003 Appointment of the current Commission for a constant update of the Plan

The Commission for the update of the National Emergency Plan of the Vesuvius Area involves the following boards:

Presidency of the Council of Ministers - Civil Protection Department;

Vesuvius Observatory of the National Institute of Geophysics and Volcanology

Region Campania;

Local Government Office of Naples, Avellino, Benevento, Salerno;

Provinces of Naples, Avellino, Benevento, Salerno;

18 Municipalities of the Vesuvius red zone;

Italian Railway Network;

Italian Motorway S;

Anas - National Autonomous Road Company;

Enac - National Board for Civilian Aviation;

General Command of of Port Authorities;

Ministry of Education, University and Scientific Research;

Ministry of Interior - Public Safety;

Ministry of Interior - Fire Department.

The Commissions that from 1991 elaborate and update emergency planning in the Vesuvius area are established by the Civil Protection Deparment.

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Dangerous zones Alert levels What happens in case of an ongoing eruption Plan evolution NATIONAL EMERGENCY PLAN The national emergency plan to protect the inhabitants from a possible eruption of the Vesuvius area has as its baseline the explosive event of 1631.

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This week marks the 71st anniversary of the most recent eruption from Italy's famed Vesuvius. Not only is the volcano one of the most picturesque in the world, but also can be argued to be the most dangerous. However, Vesuvius has been remarkably quiet for the last 71 years after thousands of years of activity. Does this mean we can expect another eruption from Vesuvius in the near future? All the signs right now would suggest not, but by no means is the threat that the volcano poses on the Bay of Naples area diminished.

For most people, when you mention Vesuvius, they might think of the 79 AD eruption that buried Pompeii and Herculaneum. The victims of that eruption were forever cast in their death poses by ash fall and pyroclastic flowsfrom Vesuvius. It was also the eruption that Pliny the Younger observed from across the Bay of Naples. His vivid descriptions of the eruption lead volcanologists to name the style of eruption - a towering ash plume that reaches neutral bouynacy over 30 kilometers above the volcano, forming an umbrella-shaped cloud - a Plinian eruption.

However, like many famous volcanoes, Vesuvius' history is much more than the single eruption in 79 AD. Since that eruption, the volcano has produced dozens of eruptions, many of which were VEI 3 or greater and 6 of those were as big if not bigger than the 1980 eruption of Mount St. Helens. In fact, the 1631 eruption of Vesuvius was as powerful as the 79 AD eruption, yet far fewer know about it even though as many as 6,000 people may have died in that event.

The 1944 eruption of Vesuvius was one to behold. Italy was beginning to emerge from its time as an Axis power and Allied forces were occupying the Bay of Naples. You can get the mood from this excellent newsreel about the eruption from 1944. It has some amazing footage of lava flows from Vesuvius knocking down walls in the towns that had built up on the slopes of the volcano. Even the relics of St. Januarius were trotted out to help fight back the lava from the volcano.

Not only that, but Allied B-25s of the 340th Bombardment Group were stationed almost at the foot of the volcano. Over 80 planes were destroyed by the ash fall from the eruption (see above), with Vesuvius taking out more B-25s than a Nazi air raid later in the year. Don Kaiser has a great site that recounts the events that lead up to the eruption and the eruption itself. The personal recollections of airmen stationed near Vesuvius capture what an astonishing set of circumstances it must have been for most of them - fighting a war in Europe and now a volcano erupts in their midsts. The continental United States had not experienced anything like this since the 1915 eruption at Lassen Peak in remote northern California, so few airmen would have any experience, either directly or through stories, of a volcanic eruption. The lava and ash from Vesuvius must have seemed like the Earth joining in on the battle taking place across Europe.

Since 1944, nothing has happened at Vesuvius. After centuries of restlessness punctuated by large explosive eruptions, Vesuvius seems to have slipped into a bit of a nap. This doesn't mean that Vesuvius is done or that the volcano is any less hazardous. In fact, this quiet makes it potentially more challenging to create a volcanic mitigation plan for the area around Vesuvius because there isn't agreement about what exactly the future holds for one of Europe's most prominent volcanoes.

Some volcanologists think that Vesuvius has the potential for another very large eruption, on the scale of the 1631 or 79 AD event. This is based on geophysical evidence derived from looking at how seismic waves generated by earthquakes move underneath the volcano. They suggest that there might be partially molten material (read: magma) at a depth of 8 to 10 kilometers below Vesuvius. Now, the tricky thing here is whether this magma is able to erupt or not. It very well could merely be cooling magma from the long bout of activity the volcano just wrapped up.

Others think that over the past 20,000 years, the magmatic system has fundamentally changed under the volcano. Instead of a deep chamber that can produce very large explosive eruptions, t hey suggest that the magmatic system is getting shallower (the 1944 eruption magma may have been stored only a few kilometers down) and thus less likely to produce a massive explosive eruption.

In either scenario, planning is the key for saving lives when Vesuvius rumbles back to life. The metropolitan area around Naples has a population over 3 million, meaning any evacuation that might be needed could be some of the most challenging that we've experienced around a volcano. The roads around Naples aren't designed for the immense volume of traffic. Most moderate eruption scenarios (akin to the 1944 event) would rain a few centimeters of ash on the area around the volcano, includes Naples itself. Worst case scenario models, using some of Vesuvius' largest eruptions, would bury downtown Naples in meters of ash. Pyroclastic flows have made it from the summit to the sea (as we saw in 79 AD) and lava flows can easier make it to the many homes that have been built on the slopes of the volcano. Let's put it this way: the situation around Naples and Vesuvius is like if we moved Rainier to the edge of the city of Seattle ... and that's not even including the Campi Flegrei calder a on the far side of the Bay of Naples!

The other problem that arises from the relatively long quiet of Vesuvius is that fewer and fewer people were alive during its last eruption. Hazard planners are well aware of the idea that the perceived threat of a disaster diminishes greatly as the memory of the last eruption fades. Convincing people to prepare now for the next Vesuvius eruption is challenging when they see a picturesque (and to them, benign) mountain in the outskirts of town. 71 years might seem like a long time on the human timescale, but for a volcano with 300,000 years of activity recorded in its slopes, this is nothing. Don't be fooled, Vesuvius has all the ingredients for a volcanic disaster: a track record of explosive eruptions, a silence long enough to lull people into complacency and a large population center at its doorstep.

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Over 70 Years of Silence from Italy's Vesuvius

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This week marks the 71st anniversary of the most recent eruption from Italy's famed Vesuvius. Not only is the volcano one of the most picturesque in the world, but also can be argued to be the most dangerous. However, Vesuvius has been remarkably quiet for the last 71 years after thousands of years of activity.

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Open University research is providing new insights into the process occurring beneath persistently active volcanoes.

Key aspects of this research

Engaged volunteers and local communities in exploring natural hazards

The formation of an international network of collaborators, mainly local scientists

Operational guidelines for monitoring and responding to volcanic crises

Helped protect the public against the hazards of volcanic degassing

OU research led by Professor Hazel Rymer in the Faculty of Science provides new insights into the process occurring beneath persistently active volcanoes. This work is shedding light on the links between changes in the magma system deep beneath a volcano and the environmental impact downwind of the volcano.Important greenhouse gases, such as sulphur dioxide and carbon dioxide are emitted in enormous quantities by some of the world's volcanoes. Their output accounts for nearly one per cent of the global total.

A key aspect of this research has been the involvement of volunteer citizen scientists and also the way it has engaged local communities.

Citizen scientists

The research has led to the formation of an international network of collaborators working closely with local communities, government-run volcano observatories, universities and citizen scientists who undertake measurements at active volcanoes across the world.

The OU has undertaken much of this research in collaboration with Earthwatch, a charity which brings individuals from all walks of life together with world-class scientists to work for the good of the planet.

Local people who live near active volcanoes get involved in and are empowered by OU research in this field

Project teams based at the persistently active volcanoes in Iceland and Central America have made significant discoveries which benefited both the volunteers and the environment.

The work has impacted on the lives of the volunteers who collect the data in the field because they are able to contribute in very real terms to scientific research. They disseminate the results through outreach activities in their home environments.

Local stakeholders including park wardens, civil defence officials and those who live near the volcanoes are empowered by this work to engage in monitoring work themselves and to play a part in hazard mitigation.

Protecting the public

Citizen scientist observations at Askja volcano in Iceland suggest that magma has been accumulating underneath since 2007 and colleagues at the Nordic Volcanological Institute increased their surveillance of the area during the summer field seasons of 2009 onwards.

More recently, the group's work at Poás volcano, Costa Rica, involved citizen scientists in predicting increased local environmental damage from 2009 and helped to inform the volcano observatory staff and National Park officials who restricted access by the public to the crater area during the degassing crisis of 2009-10, reducing the risk of injury.

To mitigate against such hazards, operational guidelines for monitoring and responding to changes in volcanic degassing were put in place in Costa Rica and Nicaragua in 2009.

Learn more about scientists' work on active volcanoes:

Publications

Williams-Jones, Glyn; Rymer, Hazel; Mauri, Guillaume; Gottsmann, Joachim; Poland, Michael and Carbone, Daniele (2008). Toward continuous 4D microgravity monitoring of volcanoes. Geophysics, 73(6) WA19-WA28

Gottsmann, J.; Camacho, A. G.; Marti, J.; Wooller, L.; Fernandez, J.; Garcia, A. and Rymer, H. (2008). Shallow structure beneath the Central Volcanic Complex of Tenerife from new gravity data: implications for its evolution and recent reactivation. Physic

Wooller, Luke; van Wyk de Vries, Benjamin; Cecchi, Emmanuelle and Rymer, Hazel (2009). Analogue models of the effect of long-term basement fault movement on volcanic edifices. Bulletin of Volcanology, 71(10) pp. 1111-1131

Carbone, D.; Zuccarello, L.; Saccorotti, G.; Rymer, H. and Rapisarda, S. (2010). The effect of inertial accelerations on the higher frequency components of the signal from spring gravimeters. Geophysical Journal International, 182(2) pp. 772-780

Carbone, Daniele; Zuccarello, Luciano; Montalto, Placido and Rymer, Hazel (2012). New geophysical insight into the dynamics of Stromboli volcano (Italy). Gondwana Research, 22(1) pp. 290-299

de Zeeuw van Dalfsen, Elske; Rymer, Hazel; Pedersen, Rikke; Sturkell, Erik; Sigmundsson, Freysteinn and Ófeigsson, Benedikt (2013). Geodetic data shed light on ongoing caldera subsidence at Askja, Iceland. Bulletin of Volcanology, 75(5) pp. 709-722

People

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Mitigating the effects of volcanoes worldwide

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Open University research is providing new insights into the process occurring beneath persistently active volcanoes. Engaged volunteers and local communities in exploring natural hazards The formation of an international network of collaborators, mainly local scientists Operational guidelines for monitoring and responding to volcanic crises Helped protect the public against the hazards of volcanic degassing OU research led by Professor Hazel Rymer in the Faculty of Science provides new insights into the process occurring beneath persistently active volcanoes.

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A state of emergency has been declared in Louisiana and Mississippi as Tropical Storm Gordon roars towards the US Gulf Coast.

With maximum sustained winds near 65mph (105km/h), Gordon is expected to make landfall later on Tuesday, the National Hurricane Center (NHC) warned.

Gordon is expected to strengthen and become a hurricane.

It could "bring life-threatening storm surge" of up to five feet (1.5m), the NHC said.

At 19:00 GMT, Gordon was about 130 miles south-east of Mobile, Alabama.

It is moving at a speed of 15mph in a north-westerly direction.

The National Weather Service in New Orleans gave tips to city residents how to prepare for the arrival of the storm.

Meanwhile, New Orleans Mayor LaToya Cantrell warned: "The city's absolute number one priority is to ensure the safety of our residents."

New Orleans was devastated by deadly Hurricane Katrina in 2005.

In its latest bulletin, the NHC said that Gordon was expected to rapidly weaken after making landfall.

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Emergency on US Gulf Coast as storm nears

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A state of emergency has been declared in Louisiana and Mississippi as Tropical Storm Gordon roars towards the US Gulf Coast. With maximum sustained winds near 65mph (105km/h), Gordon is expected to make landfall later on Tuesday, the National Hurricane Center (NHC) warned. Gordon is expected to strengthen and become a hurricane.

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Multiple Hazards - Los Angeles Case Study

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Earthquakes ; ·Not only does the San Andreas Fault, marking the conservative margin between the Pacific and North American plates, cross Southern California, but LA was built across a myriad of transform faults. These include the Santa Monica fault, the San Fernando fault, and the Northridge/Santa Barbara fault.

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A powerful earthquake has struck a popular tourist destination in Indonesia, killing at least 14 people.

The 6.4 magnitude quake hit the central island of Lombok just before 07:00 local time (00:00 GMT) on Sunday.

The island attracts tourists from around the world due to its beaches and hiking trails, and is located about 40km (25 miles) east of Bali.

More than 160 people are injured and thousands of homes are damaged, officials say.

A Malaysian tourist who was on a hiking trip to Mount Rinjani is among those killed.

The US Geological Survey said the epicentre of the earthquake was 50km (31 miles) north-east of the city of Mataram, in northern Lombok.

It was followed by more than 60 smaller earthquakes, with the largest recorded at a magnitude of 5.7.

Sutopo Purwo Nugroho, a spokesman for the country's disaster agency, said that most casualties occurred when victims were hit by debris and falling blocks of concrete.

"The main focus now is evacuation and rescue. Some of the injured are still being treated at clinics," he said.

He also posted images showing collapsed buildings and streets littered with rubble.

"The quake felt so strong... tourists were panicked and frightened and escaped from hotels," Lalu Muhammad Iqbal, a citizen protection director at the foreign ministry, told BBC Indonesian.

BBC Marathi journalist Vinayak Gaikwad was on Gili Trawangan island, about 7km from Lombok, at the time of the earthquake.

"The tremors were strong - I noticed waves in the hotel pool," he said. "A group of us ran out of the hotel.

"Thirty minutes later there was the first strong aftershock. The locals were worried because many of their structures are made from wood and bamboo, but the tourists were the most scared."

One witness told AFP news agency about the chaos that followed the earthquake.

"The earthquake was very strong... and everybody in my house panicked, we all ran outside," he said. "All my neighbours also ran outside and the electricity was suddenly cut off."

Mount Rinjani National Park, a popular destination for trekkers, has been closed due to landslides.

Climber Khairul Azi told the New Straits Times he and a group of hikers were "unable to get out of the area because many roads have been cut off".

"The situation here is hectic and we're still trying to make contact with the other Malaysian climbers," he added.

Indonesia is prone to earthquakes because it lies on the Ring of Fire - the line of frequent quakes and volcanic eruptions that circles virtually the entire Pacific rim.

More than half of the world's active volcanoes above sea level are part of the ring.

A magnitude 6.5 quake struck off the north-east coast of Sumatra island in 2016, killing dozens of people and displacing more than 40,000.

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Deadly quake hits Indonesia tourist spot

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A powerful earthquake has struck a popular tourist destination in Indonesia, killing at least 14 people. The 6.4 magnitude quake hit the central island of Lombok just before 07:00 local time (00:00 GMT) on Sunday. The island attracts tourists from around the world due to its beaches and hiking trails, and is located about 40km (25 miles) east of Bali.

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A powerful magnitude 7.1 temblor rocked Southern California at 8:19 PT on July 5, 2019, just 34 hours after a magnitude 6.4 earthquake hit the same region. This is the largest in decades, with the last temblor this large-the magnitude 7.1 Hector Mine earthquake-striking the Mojave Desert in 1999.

This latest event was widely felt, causing several fires and damage to buildings and roads in Ridgecrest and nearby, but reports on the impacts are still emerging. Aftershocks are expected to continue, with a 27 percent chance that as many as two earthquakes of magnitude 6 or higher could occur within the next week.

About earthquakes

Earthquakes, also called temblors, can be so tremendously destructive that it's hard to imagine they occur by the thousands every day around the world, usually in the form of small tremors. See the latest earthquakes and learn how to stay safe during these disastrous events.

Where do most earthquakes occur?

Some 80 percent of all the planet's earthquakes occur along the rim of the Pacific Ocean, called the "ring of fire" because of the preponderance of volcanic activity there, as well. Most earthquakes occur at fault zones, where tectonic plates-giant rock slabs that make up Earth's upper layer-collide or slide against each other.

These impacts are usually gradual and unnoticeable on the surface; however, immense stress can build up between plates. When this stress is released quickly, it sends massive vibrations, called seismic waves, often hundreds of miles through the rock and up to the surface. Other quakes can occur far from faults zones when plates are stretched or squeezed.

Earthquake magnitude ratings and their impacts

Scientists assign a magnitude rating to earthquakes based on the strength and duration of their seismic waves. A quake measuring 3 to 4.9 is considered minor or light; 5 to 6.9 is moderate to strong; 7 to 7.9 is major; and 8 or more is great.

On average, a magnitude 8 quake strikes somewhere every year, and some 10,000 people die in earthquakes annually. Collapsing buildings claim by far the majority of lives, but the destruction is often compounded by mud slides, fires, floods, or tsunamis. Smaller temblors that usually occur in the days following a large earthquake can complicate rescue efforts and cause further death and destruction.

Loss of life can be avoided through emergency planning, education, and the construction of buildings that sway rather than break under the stress of an earthquake.
Warning: Some of the photos below contain graphic imagery.

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Learn where earthquakes happen and how they're rated

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A powerful magnitude 7.1 temblor rocked Southern California at 8:19 PT on July 5, 2019, just 34 hours after a magnitude 6.4 earthquake hit the same region. This is the largest in decades, with the last temblor this large-the magnitude 7.1 Hector Mine earthquake-striking the Mojave Desert in 1999.

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New Zealand: Case study of a country with multiple hazards MULTIPLE HAZARDS: NZ is a geomorphologically, geologically and meteorologically unstable country wh...

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Revision material for students at The Radclyffe School studying AQA Geography B syllabus.

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Climate Change increase hazards around the world

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Climate Change increase hazards around the world

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ATTRIBUTION | August 4. 2022. 16:30

In the early 2000s, a new field of climate-science research emerged that began to explore the human fingerprint on extreme weather, such as floods, heatwaves, droughts and storms.

Known as "extreme event attribution", the field has gained momentum, not only in the science world, but also in the media and public imagination. These studies have the power to link the seemingly abstract concept of climate change with personal and tangible experiences of the weather.

Scientists have published more than 400 peer-reviewed studies looking at weather extremes around the world, from wildfires in the US and heatwaves in India and Pakistan to typhoons in Asia and record-breaking rainfall in the UK. The result is mounting evidence that human activity is raising the risk of some types of extreme weather, especially those linked to heat.

To track how the evidence on this fast-moving topic is stacking up, Carbon Brief has mapped - to the best of our knowledge - every extreme-weather attribution study published to date.

Carbon Brief's analysis reveals:

71% of the 504 extreme weather events and trends included in the map were found to be made more likely or more severe by human-caused climate change.

9% of events or trends were made less likely or less severe by climate change, meaning 80% of all events experienced some human impact. The remaining 20% of events and trends showed no discernible human influence or were inconclusive.

Of the 152 extreme heat events that have been assessed by scientists, 93% found that climate change made the event or trend more likely or more severe.

For the 126 rainfall or flooding events studied, 56% found human activity had made the event more likely or more severe. For the 81 drought events studied, it's 68%.

First published in July 2017, this article is the fifth annual update (see endnote) to incorporate new studies. The aim is that it serves as a tracker for the evolving field of "extreme event attribution".

Using the map

The map above shows 504 extreme weather events and trends across the globe for which scientists have carried out attribution studies. The different symbols show the type of extreme weather; for example, a heatwave, flood or drought. The colours indicate whether the attribution study found a link to human-caused climate change (red), no link (blue) or was inconclusive (grey).

How to use our map of attribution studies.

Use the plus and minus buttons in the top-left corner, or double click anywhere, to zoom in on any part of the world. Click on a symbol to reveal more information, including a quote from the original paper to summarise the findings and a link to the online version.

The filter on the left allows users to select a specific type of weather event to look at or, for example, only those found to be influenced by climate change.

The filter can also be used to highlight extreme events from a particular year. (Note: earlier versions of this map classified events by the year that the study or analysis was published.) To isolate studies that assess the changing trends of weather extremes, click the "trend" box in the filter.

The software used to make the map currently only works with a Web Mercator projection (as used by virtually all major online map providers). It is worth noting that this - like all map projections - offers a somewhat distorted view of the world.

It is important to note that the weather events scientists have studied so far are not randomly chosen. They can be high-profile events, such as Hurricane Harvey, or simply the events that occurred nearest to scientific research centres. (More on this below.)

The map includes three different types of studies. The circles and hexagons on the map indicate papers published in peer-reviewed journals. The different shapes refer to whether the study considers an individual extreme event (circles), such as a wildfire or storm, or whether it analyses longer-term trends in extreme weather (hexagons), such as the change in frequency of flooding or marine heatwaves over time.

The third shape - triangles - indicate rapid attribution studies. These are quickfire assessments of the climate change contribution to extreme weather events, published online shortly after an event concludes. (More on this below.)

Finally, it is worth noting that some of the icon locations are approximate - particularly for studies that cover large regions. For example, global studies can be found grouped together in the middle of the Atlantic Ocean.

Extreme weather types

The events and trends shown on the map are covered by 431 individual scientific papers or rapid studies. Where a single study covers multiple events or locations, these have been separated out into individual entries on the map.

Combining the evidence over the past 20 years, the literature is heavily dominated by studies of extreme heat (30%), rainfall or flooding (25%) and drought (16%). Together, these make up more than two-thirds of all published studies (71%). The full list is available in this Google sheet.

As the chart below shows, the number of extreme events studied has grown substantially over the past 10-15 years. Note that formal studies typically follow a year or so after the event itself as the writing and peer-review process for journal papers can take many months.

The majority of studies included here have been published in the annual "Explaining extreme events" special issues of the Bulletin of the American Meteorological Society ( BAMS). Each bumper volume typically contains around 15-30 peer-reviewed studies of events from the previous year. Other studies have been found through the Climate Signals database and online searches through journals. This update includes studies published up to the end of May 2022.

(Note: The map currently only includes studies published in English.)

Specific types of event can be displayed in the chart below by clicking on the category names at the top.

Number of attribution studies by extreme weather event type and year. Note: the total number of events dipped in 2017 because the Bulletin of the American Meteorological Society special report for that year was published in early 2018 rather than late 2017. Chart by Carbon Brief using Highcharts.

Most of the categories of extreme weather are self-explanatory, but "storms" and "oceans" require a bit of explanation.

For this latest iteration of the map, a new category of "compound" extreme events has also been added. This includes, for example, a 2021 study that found climate change had contributed to the "high likelihood" of combined dry and hot events in recent decades over most of China.

A man wades through a flooded road in Madagascar, after tropical cyclone Batsirai, Feb 2022. Credit: Xinhua / Alamy Stock Photo.

Such studies show that attribution studies are increasingly considering the impacts of extremes, rather than focusing purely on the weather event.

This shift towards impacts "is quite significant", says Prof Peter Stott, who leads the climate monitoring and attribution team at the Met Office Hadley Centre and has been a co-editor of the BAMS reports since they began in 2012. He tells Carbon Brief:

"Impacts are hard to do because you have to establish a significant link between the meteorology and the impact in question. As editors, we've been trying to encourage more studies on impacts because it's the impacts rather than the meteorology per se that tends to motivate these types of study - and if we only have the attribution on the meteorological event then we only have an indirect link to the relevant impact."

Attribution of climate impacts could even be used in the courts, one 2021 study explained. The authors wrote a Carbon Brief guest post explaining how attribution science can be "translated into legal causality". They wrote:

"Attribution can bridge the gap identified by judges between a general understanding that human-induced climate change has many negative impacts and providing concrete evidence of the role of climate change at a specific location for a specific extreme event that already has led or will lead to damages."

Human influence on extreme weather

Of the attribution studies included here, scientists found that human-caused climate change has altered the likelihood or severity of an extreme weather event in 80% of cases studied (71% made more severe or likely and 9% made less so).

In Carbon Brief's first edition of this analysis in 2017, 68% of events were found to have a human impact (with 63% made more severe or likely and 6% less so).

While these figures are not representative of all extreme weather events - attribution studies have only been conducted on a relatively small number - previous research has taken this broader view. For example, a 2015 study estimated the fraction of all globally occurring heat and heavy rainfall extremes that was attributable to warming. The authors found that around 75% of "moderate daily hot extremes over land" and 18% of "moderate daily precipitation extremes over land" were attributable to the observed temperature increase since pre-industrial times. These fractions are expected to increase with further warming, the authors noted.

Note that events are classified here as having an human impact if climate change is found to have influenced at least one aspect of that event. For example, a study of the 2011 East Africa drought found that climate change contributed to the failure of the "long rains" in early 2011, but that the lack of "short rains" in late 2010 was down to the climate phenomenon La Niña. This event is, thus, designated as having a human impact.

For the majority of events affected by climate change, the balance has shifted in the same direction. That is, rising temperatures made the event in question more severe or more likely to occur. These events are represented by the red in the chart below. Clicking on the red "slice" reveals that heatwaves account for 40% of such events, rainfall or flooding for 20%, and droughts for 15%. Return to the original chart, and do the same with the other slices to see the proportion of different weather types in each category.

Pie chart showing the proportion of extreme events/studies that were found to have been made more likely/severe by climate change (red segment), less likely/severe (orange), had no link identified (blue) and were inconclusive or lacked sufficient data (grey). Clicking on a segment reveals the makeup of different types of extremes within that category. Chart by Carbon Brief using Highcharts.

In 11% of extreme weather events and trends studied, scientists found no discernible influence from human activity. These are coloured blue in the map and the chart above. For a further 9%, the observational data or modelling techniques used in the study were insufficient to reach a reliable conclusion (shown as grey in the map and pie chart).

In 9% of studied weather events and trends, scientists found climate change had made the event less likely or less severe (pale orange in the chart above).

Interestingly, a 2020 study analysed the way links between climate change and the California drought were portrayed in US media. It finds that the links were "covered widely in both local and national news", but notes:

"However, legitimate differences in the methods underpinning the attribution studies performed by different researchers often resulted in a frame of scientific uncertainty or disagreement in the media coverage."

As the case of California's drought shows, it is often necessary to dig deeper to understand the full picture. The rest of this article looks at the evidence for the three most-studied types of extreme weather - heatwaves, heavy rain and floods, and droughts - as well as some of the main issues in event attribution, and where the field as a whole is heading.

Heatwaves

The attribution map includes studies of 152 extreme heat events, of which 142 (93%) have been made more likely or more severe because of climate change. No studies have found a heatwave that has been made less severe by climate change, while studies of two events (1%) identified no influence and a further eight (5%) were inconclusive.

A volunteer pours water on a pedestrian during a heatwave in southern Pakistan, May 2022. Credit: Xinhua / Alamy Stock Photo.

The studies on extreme heat that did not find a role for climate change were an analysis of the Russian heatwave in 2010 and a rapid attribution study of the all-time high temperatures recorded in Rajasthan, India in May 2016. For the latter, the authors suggested that "the lack of a detectable trend may be due to the masking effect of aerosols on global warming and increased use of irrigation".

A particularly well-studied region for heatwaves in the literature is Australia, which accounts for 10% of the heat-related events included here. And climate change was found to play a role in all but one of the 15 Australian heat events studied. It is worth noting for that one event, however, that although the study (pdf, p145) was inconclusive for the city of Melbourne in south-east Australia, the authors did detect a human influence on extreme heat up the coast in Adelaide.

This raises a few important points. First, finding that climate change contributed to an event is not the same as saying it "caused" that event. Attribution is about working out if the likelihood or magnitude of a particular event happening now is different from what it would be in a world that was not warming.

A useful analogy - as explained in the first BAMS report in 2012 - is of a baseball player who starts taking steroids. If the player begins hitting 20% more home runs than before, it would not be possible to say for sure whether a particular home run is because of the steroids or the player's spontaneous skill. But it is possible to say how the steroids have altered the likelihood that the player hits a home run, by comparing their current and historical performances. As the report put it:

"Given that steroids have resulted in a 20% increased chance that any particular swing of the player's bat results in a home run, you would be able to make an attribution statement that, all other things being equal, steroid use had increased the probability of that particular occurrence by 20%."

Another important point is that in cases where attribution science finds that climate change is making a given type of extreme weather more likely, it does not necessarily follow that the chance of experiencing that kind of weather gets incrementally higher each year. Natural variability means that there will still be ups and downs in the strength and frequency of extreme events.

Finally, there is usually a level of confidence attached to attribution results. So, while two studies might both find a role for human influence in a given weather event, the signal may be stronger for one than the other. For the purposes of this analysis, the attribution map does not distinguish between high- and low-confidence results, but users can click through to each study for more details.

Heavy rain and flooding

Of the 126 rainfall or flooding events included in the attribution map, 71 (56%) found human activity had made the event more likely or more severe - a far smaller proportion than for heat-related studies. Nineteen studies (15%) found that climate change had made the whole event less likely to occur. Of the remaining heavy rainfall events, studies of 24 (19%) found no evidence of a link to climate change, while 12 (10%) were inconclusive.

That there is a more divided set of results for extreme rainfall than for heatwaves could suggest several things. In some cases, limited data might make it difficult to detect a clear "signal" of climate change above the "noise" of weather considered normal for a particular region. In other cases, an inconclusive result could reflect the fact that rainfall or flooding events are inherently more complex than heatwaves, with many ways for natural variability to play a role. Human factors, such as land use and drainage, also play a part in whether heavy rain leads to flooding.

Volunteers help move sandbags to protect a home from rising flood waters near Ottawa Canada, during 2019 floods. Credit: Colin Clarke / Alamy Stock Photo.

Take the UK, for example. While one study found climate change had increased the risk of floods in England and Wales in Autumn 2000 by at least 20% (and even up to 90%), another found little influence on summer rainfall in 2012 (pdf, p36).

This raises another important point. When it comes to interpreting the results of event attribution studies, it matters what the question is. For example, a 2013 study asked whether recent wet summers in north-western Europe were a response to retreating Arctic sea ice (pdf, p32). The answer from the study was "no". But, as a foreword from that year's BAMs report explains:

"Given the numerous ways climate change could influence precipitation in this region, a 'no' result for the role of Arctic sea ice should not be interpreted as an absence of any role at all for climate change."

The paper notes that, in a chaotic weather system, the complex dynamics of the atmosphere mean the size and path of a storm or heavy rainfall event has a large element of chance. This can make it tricky to identify where climate change fits in, potentially underestimating its influence.

Therefore, rather than analysing the weather patterns that bring a storm to an area, the authors argue that scientists should be looking at how the impact of that storm has been boosted by temperature changes - known as "thermodynamic" effects. Higher temperatures mean warmer seas, higher sea levels and more moisture evaporating into the atmosphere. These are changes that scientists can be more confident in, the authors wrote, and so should be the focus for attribution studies - rather than looking at changes to circulation patterns in the atmosphere.

For example, the paper reexamines an earlier study (pdf, p15) that suggested climate change had reduced the chances of the five-day heavy rainfall event that hit north-east Colorado in September 2013. Trenberth and colleagues argue that while climate change might not have made the specific weather system that brought the rain more likely, it will have contributed to the sheer volume of moisture in the atmosphere.

Chart shows the number of studies for each type of extreme event that fall within each category of human influence: More severe/likely (red), less severe/likely (yellow), no influence (blue) and inconclusive (grey). Chart by Carbon Brief using Highcharts.

While attribution studies of heatwaves are generally more straightforward than storms - as they focus on thermodynamic influences - the type of question they are asking is still important. The Russian heatwave in 2010 is a good example of this. One study looking at the severity of the event did not find a role for climate change. Yet another one, which did find an influence, looked at the likelihood of the event.

This apparent contradiction is tackled by a third study that reconciles the other two. It explains that "the same event can be both mostly internally-generated [i.e. by natural variability] in terms of magnitude and mostly externally-driven [i.e. by human-caused climate change] in terms of occurrence probability".

Otto, who is lead author of the third study, tells Carbon Brief:

"The studies, thus, only appear to be contradictory, but are, in fact, complementary."

It is also important to stress that the absence of evidence for a link to climate change is not the same as evidence of absence. In other words, it does not necessarily mean there was no human influence, just that a particular analysis did not find one. This is why a single study should never be considered the final word on how climate change influences a given type of extreme weather.

Drought

Of the 81 drought events and trends considered here, climate change was found to have increased the severity or likelihood of 55 (68%). Of the remainder, the likelihood or severity was reduced for one event (1%), while no discernible link with human activity was found for 15 (19%) and 10 (12%) were inconclusive.

This mixed bag of results reflects the inherent complexity of droughts. And, again, the specific question matters. Conclusions about the role of climate change in a specific drought could depend on whether a study looks at temperature, rainfall or soil moisture, for example.

As the 2015 BAMS report explains:

"Drought continues to be an event type where the results require significant context, and easy answers often remain elusive because of the many meteorological, hydrological, and societal drivers that combine to cause drought."

(For more on the different ways that droughts can be categorised, see this Carbon Brief guest post from 2018.)

Geographical reach

While much has been achieved in the field of extreme event attribution in a short space of time, scientists are constantly looking for ways to tailor their work to suit the people who might use it.

One major goal since the early days of the field has been to expand extreme event attribution to cover a larger and more diverse geographical area.

Where in the world scientists can carry out attribution studies - and for what kind of events - will always be limited by the quality and availability of observed data and appropriate models. The attribution map highlights, for example, that there are relatively few studies of extreme weather in Africa and South America.

In another example, scientists hoping to analyse Super Typhoon Mangkhut - which hit the Philippines in September 2018 - were unable to in part because of "very poor quality" observed data in publicly available datasets and a lack of models.

At the moment, there is also a heavy leaning towards weather events that are local to the modelling groups, or that have a particular scientific interest. Otto explains:

"For example, scientists often do attribution studies because an event occurs on their doorstep. The UK, California and Boulder [in Colorado] are, therefore, studied much more than other parts of the world, but that does not necessarily make them places particularly impacted by climate change."

This means that while the studies carried out so far are indicative of the role climate change is playing in extreme weather around the world, they should not be considered representative of all types of extreme weather everywhere, says Otto. She tells Carbon Brief:

"[The studies so far] are part of a picture, but we don't know what's on the missing puzzle pieces. And, crucially, we don't know how many pieces are missing."

For example, Otto recently penned a Carbon Brief guest post on how the lack of monitoring of heatwaves in Africa means they are a "forgotten impact" of climate change.

Real-time extreme weather attribution

As well as expanding the science to cover different types of weather and more of the world, scientists are getting faster at turning the handle on extreme event attribution studies - sometimes crunching the numbers just days after an event has occurred.

The rapid studies included here are all produced by the World Weather Attribution (WWA) initiative, described earlier, or the UK Met Office.

An example of analysis performed by the latter includes their review of the UK's weather in 2020, which was published by Carbon Brief. This showed that climate change increased the likelihood of the UK's warm year by approximately a factor of 50.

While the WWA individual rapid assessments are not individually peer-reviewed, they are conducted using methods that have been through the peer-review process. As the 2014 BAMS report explains:

"Much like other routine analysis, such as an operational seasonal forecast, statements made about heat events using these methods do not necessarily need to go through the peer-reviewed literature to be considered credible."

By conducting the analysis in the immediate aftermath of a weather event, these rapid studies provide almost-real-time information on the influence of climate change, rather than having to wait many months for a formal study.

(In some cases, these rapid assessments are later published in peer-reviewed journals. In these instances, the formal study is included in the attribution map, rather than the initial analysis. In some cases, this means earlier rapid assessments are removed from the Carbon Brief map in order to add in the relevant peer-reviewed paper once it is published.)

The Trans Canada highway remains partially submerged by flood water after rainstorms lashed the western Canadian province of British Columbia in November 2021. Credit: Reuters / Alamy Stock Photo.

This collaboration between the UK Met Office, German weather service (DWD), Meteo France, Dutch weather service (KNMI) and the University of Oxford will "demonstrate how attribution of extreme weather events can be carried out operationally by national meteorological services", Prof Stott tells Carbon Brief:

"In this project we are developing and testing the protocols we will need to enable rapid and reliable assessments of the extent to which recent extreme weather events have been made more or less intense or more or less likely by climate change. We started at the beginning of the year and so far we have tested our procedures on an analysis of the 2018 heatwave in Europe."

The progress to date has "demonstrated the importance of international collaboration for developing new techniques and processes", says Stott. But "national meteorological services across Europe will continue to have a particular remit to deliver advice on weather and climate in their own countries", he adds:

"At the Met Office in the UK we are developing our operational attribution capability to help inform the public, policymakers and journalists about the extent to which damaging extreme weather events like the floods in Yorkshire [in 2019] have been affected by climate change."

An evolving science

As the science of extreme event attribution has matured and become more nuanced, so has the choice of terminology around extreme weather and climate change.

While some attest that all extreme weather must be affected by a world that is warming, this warrants some caution. As the first BAMS report in 2012 noted:

"While it has been argued that in the Anthropocene, all extreme weather or climate events that occur are altered by human influence on climate...this does not mean that climate change can be blamed for every extreme weather or climate event. After all, there has always been extreme weather."

But while it would be premature to suggest that any single study is the last word, it is clear that - in many cases - the science can do better than that. Similarly, scientific thinking has clearly moved on from the unsatisfactory statement that it is not possible to attribute any individual weather event to climate change. Indeed, as mentioned earlier, there have been some studies that have concluded that an event - or aspect of an event - would have been impossible without climate change.

Russian Federal Agency for Forestry works to put out a forest fire in Basly, Russia in August 2020. Credit: Reuters / Alamy Stock Photo.

Ultimately, there are no blanket rules in attribution. Scientists need to examine the circumstances of each individual weather event - or a longer pattern of events for trend studies. It is only by combining evidence from all around the world that they can begin to draw broader conclusions.

Attribution studies, therefore, rely heavily on the quality and availability of observational data and climate model simulations. In a short paper for the journal Weather, Dr Otto says that "the models used for attribution need to be able to reliably estimate the likelihoods of the types of events being attributed".

As discussed earlier, attribution studies of heatwaves tend to be more straightforward because of their focus on thermodynamic effects, rather than atmospheric circulation. Yet, Otto tells Carbon Brief that recent studies suggest models overestimate the year-to-year variability of heat extremes in some parts of the world, and thus underestimate the trend and the role of climate change.

In a rapid attribution study of the western Europe summer heatwave in 2019, for example, Otto and her colleagues found that, for the month of June, the models "show about 50% smaller trends than observations in this part of Europe and much higher year-to-year variability than the observations". Similarly, a study of the 2019-20 Australian bushfires noted that "models underestimate the observed trend in heat" and so the "real increase could be much higher".

These findings emphasise how important it is to analyse models and observations together, Otto says:

"This made me realise just how important attribution is for the scientific community - and everyone using climate science - at bringing observations and models together in a very concrete real-world test case.

Attribution can, therefore, be used to help scientists "identify where the models are doing well and for what they are not in a much more direct way than the classical skill assessment of climate projections does", adds Otto.

Forecasted attribution

One attempt to move attribution science forward was the very first "advance forecasted" attribution analysis, which quantified the impact of climate change on the size, rainfall, and intensity of Hurricane Florence before it made landfall in North Carolina in September 2018.

The analysis ran two sets of short-term forecasts for the hurricane: one as the climate is today and the other in a simulated world without human-caused climate change. The researchers concluded at the time:

"We find that rainfall will be significantly increased by over 50% in the heaviest precipitating parts of the storm. This increase is substantially larger than expected from thermodynamic considerations alone. We further find that the storm will remain at a high category on the Saffir-Simpson scale for a longer duration and that the storm is approximately 80km in diameter larger at landfall because of the human interference in the climate system."

The analysis received a mixed reaction. Prof Stott told Carbon Brief that it was "quite a cool idea", but would be dependent on being able to forecast such events reliably. Dr Kevin Trenberth, distinguished senior scientist at the National Center for Atmospheric Research, described it as "a bit of a disaster". He told Carbon Brief that the quality of the forecast was questionable for the assessment:

"The forecasts made were not good: the intensity of the forecast storm at landfall was category 4 or 5 as I recall, instead of category 2. And so the statements made were based on quite flawed assumptions: namely, that they had a good forecast."

A key requirement for a reliable attribution study is for models to accurately replicate the extreme event, Trenberth added, but "obviously one can not assess the goodness of the forecast if one does this in advance".

Houses in North Carolina sit in floodwater caused by Hurricane Florence. Credit: Reuters / Alamy Stock Photo.

The authors subsequently published a paper in Science Advances that "reviews the forecasted attribution with the benefit of hindsight". The findings show that climate change increased rainfall amounts "associated with the forecasted storm's core" by around 5%, and contributed to Hurricane Florence being "about 9km larger in mean maximum diameter (or a 1.6% increase in storm area) due to climate change".

The authors acknowledged that the "quantitative aspects of our forecasted attribution statements fall outside broad confidence intervals of our hindcasted statements and are quite different from the hindcasted best estimates". In short, the results are quite a way off what they forecasted.

However, the authors also said they have identified what went wrong with their forecasted analysis. Problems with the way their "without climate change" model runs were set up created a larger contrast against their real-world simulations. The results thus suggested that climate change would have a bigger impact than it actually did.

Nonetheless, the study did identify a quantifiable impact of climate change on Hurricane Florence, adding to the evidence from studies by other author groups, the researchers concluded:

"As the climate continues to warm, it is expected that extreme tropical cyclone precipitation events and resulting inland flooding will become yet more frequent."

In addition, a 2021 study of the record Australian heat event of October 2015 noted the potential of their methods "to provide attribution statements for forecast events within an outlook period". This will "allow for informed messaging to be available as required when an extreme event occurs, which is of particular use to weather and climate services", the authors wrote.

On the topic of forecasts, a 2021 study showed how it was possible to use a weather forecast model for attribution. The researchers, who penned a Carbon Brief guest post about their work, tested their methods using the European heatwave of February 2019 - an event their model successfully predicted:

"We find that the direct impact of the extra carbon dioxide (CO2) that humans have pumped into the atmosphere made the event 42% more likely for the British Isles and at least 100% (two times) more likely for France."

Their work "so far represents just the first few steps towards an operational forecast-based attribution system", they noted.

Finally, as well as casting forwards, attribution can also look back in time. A 2020 study on the US " Dust Bowl " heat and drought events of the 1930s takes an unconventional approach of looking at how the past event "would behave" with present-day levels of greenhouse gases.

The researchers find that "the return period of a 1-in-100-year heatwave summer (as observed in 1936) would be reduced to about 1-in-40 years" in today's climate.

Carbon Brief will continue to add new extreme event attribution studies to the map and update the accompanying analysis every year. Please get in touch with any suggestions of attribution studies that could be included.

This is the fifth iteration of Carbon Brief's attribution map. This is the fourth iteration of Carbon Brief's attribution map. The first, second and third and fourth editions, published in July 2017, March 2019 and April 2020, respectively, are still available at the archived links included here.

Original interactive map by Rosamund Pearce for Carbon Brief. Revised and updated by Tom Prater and Joe Goodman.

Please note: International borders are determined by the mapping software, not Carbon Brief.

Update: This article was updated on 05/08/2022 to include a mention of a 2015 attribution study of all global heat and heavy rainfall extremes.

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Mapped: How climate change affects extreme weather around the world

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In the early 2000s, a new field of climate science research emerged that began to explore the human fingerprint on extreme weather, such as floods, heatwaves, droughts and storms.

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Storm Surge Overview

Contents

Introduction

Along the coast, storm surge is often the greatest threat to life and property from a hurricane. In the past, large death tolls have resulted from the rise of the ocean associated with many of the major hurricanes that have made landfall. Hurricane Katrina (2005) is a prime example of the damage and devastation that can be caused by surge. At least 1500 persons lost their lives during Katrina and many of those deaths occurred directly, or indirectly, as a result of storm surge.

Storm Surge vs. Storm Tide

Storm surge is an abnormal rise of water generated by a storm, over and above the predicted astronomical tides. Storm surge should not be confused with storm tide, which is defined as the water level rise due to the combination of storm surge and the astronomical tide. This rise in water level can cause extreme flooding in coastal areas particularly when storm surge coincides with normal high tide, resulting in storm tides reaching up to 20 feet or more in some cases.

Storm Surge vs. Storm Tide

Factors Impacting Surge

Storm surge is produced by water being pushed toward the shore by the force of the winds moving cyclonically around the storm. The impact on surge of the low pressure associated with intense storms is minimal in comparison to the water being forced toward the shore by the wind.

Wind and Pressure Components of Hurricane Storm Surge

The maximum potential storm surge for a particular location depends on a number of different factors. Storm surge is a very complex phenomenon because it is sensitive to the slightest changes in storm intensity, forward speed, size (radius of maximum winds-RMW), angle of approach to the coast, central pressure (minimal contribution in comparison to the wind), and the shape and characteristics of coastal features such as bays and estuaries.

Click on Image to Play Video

Other factors which can impact storm surge are the width and slope of the continental shelf. A shallow slope will potentially produce a greater storm surge than a steep shelf. For example, a Category 4 storm hitting the Louisiana coastline, which has a very wide and shallow continental shelf, may produce a 20-foot storm surge, while the same hurricane in a place like Miami Beach, Florida, where the continental shelf drops off very quickly, might see an 8 or 9-foot surge. More information regarding storm surge impacts and their associated generalizations can be found in the FAQ section.

Surge animation with shallow continental shelf (Click on Image to Play Video)

Surge animation with steep continental shelf (Click on Image to Play Video)

Adding to the destructive power of surge, battering waves may increase damage to buildings directly along the coast. Water weighs approximately 1,700 pounds per cubic yard; extended pounding by frequent waves can demolish any structure not specifically designed to withstand such forces. The two elements work together to increase the impact on land because the surge makes it possible for waves to extend inland.

Although elevated, this house in North Carolina could not withstand the 15 ft (4.5 m) of storm surge that came with Hurricane Floyd (1999)

Additionally, currents created by tides combine with the waves to severely erode beaches and coastal highways. Buildings that survive hurricane winds can be damaged if their foundations are undermined and weakened by erosion.

Beachfront road and boardwalk damaged by Hurricane Jeanne (2004)

In confined harbors, the combination of storm tides, waves, and currents can also severely damage marinas and boats. In estuaries and bayous, salt water intrusion endangers the public health, kills vegetation, and can send animals, such as snakes and alligators,fleeing from flooded areas.

Damaged boats in a marina

Notable Surge Events

Surge Vulnerability Facts

From 1990-2008, population density increased by 32% in Gulf coastal counties, 17% in Atlantic coastal counties, and 16% in Hawaii (U.S. Census Bureau 2010)

Much of the United States' densely populated Atlantic and Gulf Coast coastlines lie less than 10 feet above mean sea level

Over half of the Nation's economic productivity is located within coastal zones

72% of ports, 27% of major roads, and 9% of rail lines within the Gulf Coast region are at or below 4 ft elevation (CCSP, SAP 4-7)

A storm surge of 23 ft has the ability to inundate 67% of interstates, 57% of arterials, almost half of rail miles, 29 airports, and virtually all ports in the Gulf Coast area (CCSP SAP 4-7)

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Contents Introduction Along the coast, storm surge is often the greatest threat to life and property from a hurricane. In the past, large death tolls have resulted from the rise of the ocean associated with many of the major hurricanes that have made landfall.

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Here’s how hurricanes form—and why they’re so destructive

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Also known as typhoons and cyclones, these storms can annihilate coastal areas. The Atlantic Ocean’s hurricane season peaks from mid-August to late October.

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- to know what a tropical storm is

- to be able to explain the physical processes leading to the formation of a tropical storm

- to be able to describe the locations in which we find tropical storms

- to know how the Saffir-Simpson scale is used to classify tropical storms

Note: Depending on where you are in the world, you may call these weather systems by a different name. In the USA, once wind speeds reach 74 mph they are referred to as hurricanes; in Bangladesh, they are called tropical cyclones; in Japan, people speak of typhoons; in Australia, they have willy-willies. All of these terms refer to the same weather event.

Tropical storms are areas of intense low pressure. On a satellite image, a tropical storm will show as a huge, swirling mass of cloud. The eye (calm area) is at the centre. You can see this in the image below. It shows Tropical Storm Edzani over the Southern Indian Ocean and was taken on 7th January 2010.

There are several stages in the formation of a tropical storm. These storms occur over water in areas where the sea surface temperature is at least 27 degrees. Essentially, this means that they form between the Tropic of Cancer and the Tropic of Capricorn (hence the name 'tropical' storm). They rarely occur within 5 degrees either side of the equator because the Coriolis force is too weak here.

Tropical cyclones use warm, moist air as fuel. That is why they form only over warm ocean waters near the equator. The warm, moist air over the ocean rises rapidly upward from near the surface and becomes saturated with evaporated moisture. This means that there is less air left at the surface (i.e. low pressure). Air from surrounding areas with higher air pressure pushes in to the low pressure area to try to equalise the pressure. Then that "new" air becomes warm and moist and rises, too. As the warm air continues to rise, the surrounding air swirls in to take its place. Trade winds cause the moist air to spin inwards. As the warmed, moist air rises and cools off, the water in the air forms towering cumulonimbus thunderclouds (because there is a huge amount of condensation). The whole system of clouds and wind spins and grows, fed by the ocean's heat and water evaporating from the surface. The diagram below shows a cross section through a tropical storm.

Storms that form north of the equator spin counterclockwise. Storms south of the equator spin clockwise. As the storm system spins faster and faster, an eye forms in the centre. It is very calm and clear in the eye, with very low air pressure. Higher pressure air from above flows down into the eye.

The video clip below explains this process in images.

When the winds in the rotating storm reach 39 mph, the storm is called a tropical storm. When the wind speeds reach 74 mph, the storm is officially a tropical cyclone, or hurricane. The strength of a storm is measured using the Saffir-Simpson scale, as shown in the table below.

Tropical cyclones usually weaken when they make landfall (i.e. hit the land) because they are no longer being fed by the energy from the warm ocean waters. In the northern hemisphere they track (i.e. move) westwards due to the Coriolis effect. The video clip below shows Hurricane Dean, from birth to death.
BBC animation - the formation of a hurricane NASA animated guide to the development and structure of tropical storms Make a tropical storm - simulator Investigate how winds work together to determine where a hurricane will strike - simulator BBC Bitesize revision notes about the formation of tropical storms
Useful weblinks:

Learning objectives:

- to be able to distinguish between primary and secondary effects of tropical storms

- to be able to categorise the effects of tropical storms into social, economic and environmental (SEE)

- to understand why storm surges can accompany the landfall of a tropical storm
Primary effects of tropical storms
We have already seen that the effects of earthquakes and volcanoes can be classified into primary and secondary effects. The same is true of the effects of tropical storms. Primary effects are those that result directly from the event itself. Secondary effects are those that result from the primary effects. The exam specification states that you must be able describe effects in both of these categories.
Secondary effects of tropical storms
Primary effects of tropical storms include high winds, torrential rain and storm surges at landfall (more about this one later on). There may also be localised tornadoes and waterspouts. These are all physical effects.

Secondary effects of tropical storms are very wide-ranging. We tend to divide them into social, economic and environmental effects (the SEE classification). To remember this, think about how a good geographer must open their eyes and SEE the world!
Social effects of tropical storms
Why not watch the video clips below (about Hurricane Andrew and try to make a list of the primary and secondary effects of the storm. You should also try to classify them into social, economic and environmental. Use the video clips to give you ideas, but do not limit yourself to the information included in the clips!

There are likely to be food and water shortages.

As a result of extensive flooding, people may catch water-borne diseases. This may eventually lead to death.

Communities are displaced from their homes, and may be broken up if the area is not restored. Many people are made homeless.

People suffer from stress due to loss of possessions and housing.

There may be looting of properties - domestic and commercial.

People may lose their jobs if they work in an industry that has been badly affected.

If insurance premiums rise in the future, some people may not be able to afford them and will consequently not be financially protected against future storms.
Economic effects of tropical storms
People might be stranded due to flooding - this will cause trauma.

There are the obvious costs of repairing any damage caused.

Insurance claims will be made, and this may cause the cost of insurance premiums to rise in the future.

Whilst businesses are closed, earnings (and profits) will be lost.

Crops may be damaged and exports lost. These may be a key source of income for the local economy.
Environmental effects of tropical storms (sometimes referred to as physical effects)
Oil prices may increase (this was a significant effect in the aftermath of Hurricane Katrina).

A huge amount of water is released in a tropical storm so there will be extensive flooding.

Flooding might led to swer systems being flushed out and spreading disease.

There will be structural damage to buildings and they may have to be pulled down and rebuilt. This is very costly. Other buildings may have broken windows, chimneys etc.

Roads and other infrastructure such as railways may be destroyed. This can lead to communication problems.

Electricity lines might be blown down and, as a result, people could be without power supplies.

Sensitive ecosystems may be destroyed and plant and animal habitats lost.

Sea fish are often killed because of silting, and freshwater fish may be killed in storm surges.

Fishing boats and other craft may be damaged.

Crops and livestock may be damaged or destroyed.
Storm surges
Mudslides become common because the soil is saturated. They will flow quickly down hillsides and may bury houses, crops and livestock (or even people).

Storm surges occur where the sea level along a shoreline rises as the result of a storm. This is shown in the diagram below.

There are two main causes of storm surges (described below and shown on the accompanying diagram):

1. The eye pile. The low pressure draws the water beneath it upwards to form the eye pile. It gets dragged along with the eye. The eye pile grows in height as it is forced into shallower water. It splats onto the land as the storm makes landfall.

2. Wind-blown water. Zonal winds push the water in the same direction that they are moving. If the winds blow long enough and hard enough, the water banks up and floods the land when the winds blow onshore.

The shape of the coastline will affect the likelihood of there being a damaging storm surge. The steepness of the shoreline affects the manner in which the waves strike it, as shown on the two animations below.

Storm surges can cause considerable damage to property and to people!

Useful weblinks:

An experiment to see how the shape of the coastline affects storm surges - you will need playdough, sugar cubes and a hair-dryer!

Learning objectives:

- to develop a case study factfile for Hurricane Katrina

- to begin to consider how the effects of tropical storms might vary among countries with different levels of economic development

The exam specification requires you to study the effects of tropical storms in both MEDCs and LEDCs so that you can compare how they vary among countries with different levels of economic development.

Hurricane Katrina struck in August 2005. It tracked over the Gulf of Mexico and devastated most of the coastline from Louisiana to Alabama (see map below). It arrived as a category 4 storm with winds of over 140 mph and a storm surge of approximately 6 metres. The city of New Orleans was very badly affected because it is mostly below sea-level and is surrounded by water. The city was protected by defence walls called levees. However, the levees were overwhelmed by the extra water from the storm surge and rainfall, and many collapsed allowing water to flood into the city. About 80% of the city was flooded to depths of up to 6 metres.

The National Hurricane Centre predicted accurately where Hurricane Katrina would make landfall and how strong it would be. This gave people the opportunity to prepare for the storm. The mayor of New Orleans ordered people to evacuate the city. About 80% of the city's residents did so, but about 20% remained. The majority of these were in the poorest areas of the city (people had little access to transport so couldn't leave in many cases).

Over 10,000 people sought refuge in the city's Superdome football stadium. Conditions here deteriorated quickly - food and water soon ran out and the toilet facilities were inadequate. The atmosphere in the stadium was described as 'very tense and unsafe'.

More than 80% of the city was submerged with floodwater and over 1200 people drowned. Approximately 1 million people were made homeless and thousands of businesses were destroyed. Thousands of jobs were lost and millions of dollars lost in tax income. There was a lot of looting. Criminal gangs roamed the streets, looting homes and businesses and committing other crimes.

Major highways were disrupted and some major road bridges were destroyed. Agricultural production was badly damaged by the tornaodes and also by flooiding. Cotton and sugar-cane crops were flattened.

Hurricane Katrina didn't just impact people in the USA. Many offshore oil facilities were damaged and supplies of oil were reduced. This caused the price of oil to rise on the global markets and the price of petrol in the UK rose as a result.

Estimates suggest that Hurricane Katrina has cost over $300 billion. This makes it one of the costliest hurricanes ever to hit the USA.

Useful weblinks:

The Met Office's guide to Hurricane Katrina for GCSE students (this is well worth reading as a summary of the case study)
BBC animation showing Katrina's track and where she made landfall BBC guide to how the levees were repaired in New Orleans
BBC Special in-depth report on Hurricane Katrina - lots of useful weblinks from this page

Learning objectives:

- to develop a case study factfile for Cyclone Sidr

- to begin to consider how the effects of tropical storms might vary among countries with different levels of economic development

Cyclone Sidr formed in the central Bay of Bengal and quickly strengthened to reach sustained winds of 160 mph, making it a category 5 storm. The storm eventually made landfall in Bangladesh on November 15, 2007. It weakened quickly after landfall.

The Joint Typhoon Warning Centre predicted the scale and location of landfall and so people were forewarned. Government officials were recalled from their weekly leave. Ports were closed. There was mass-scale evacuation of the coastal area, much of which is land below sea-level. The image below shows the storm surge prediction for the area. 2 million people were evacuated to emergency shelters. Over 40,000 Red Crescent volunteers were deployed to order residents in the 15 affected provinces into special cyclone and flood shelters (see image below). Relief organisations distributed seven-day emergency disaster kits of food, blankets and clothing for evacuated families.

Coastal districts of Bangladesh faced heavy rainfall as an early impact of the cyclone. The damage in Bangladesh was extensive, including tin shacks flattened, houses and schools blown away and enormous tree damage. The entire cities of Patuakhali, Barguna and Jhalokati District were hit hard by the storm surge of over 5 metres. About a quarter of the world heritage site Sunderbans were damaged. Researchers said mangrove forest Sunderban will take at least 40 years to recover itself from this catastrophe. Much of the capital city of Dhaka was also severely affected, as electricity and water service were cut and significant damage was reported there due to winds and flooding.The local agricultural industry was also devastated, as many rice crops - which have a December harvest - were lost.

This presentation from the charity CAFOD shows some of the work they have done in the area since the cyclone hit.
BBC News - Cyclone Sidr in pictures Guardian newspaper in-depth report Interactive learninbg activities from Games4Geog
Useful weblinks:

Learning objectives:

- to know how tropical storms are monitored

- to be able to describe and explain some of the startegies used in LEDCs and MEDCs to reduce the damaging effects of tropical storms
Forecast
There are three steps that people are urged to follow to reduce the damage from tropical storms:

Rich MEDCs, such as the USA, can invest in technology to predict the general area in which hurricanes will strike. This technology is not so readily available to LEDCs, although many countries receive information from organisations such as the Joint Typhoon Warning Centre (Pacific) or National Hurricane Centre (Atlantic) to help them prepare for storms. The track of a tropical storm is affected by a great many fators, so they are very unpredictable. Forecasters have a 20-25% chance of knowing exactly where a tropical storm will hit 48 in advance of landfall.
Prepare
Forecasts are made available to residents on the internet so that they can make decisions about whether they need to evacuate. This is obviously a much more useful means of communication in an MEDC where the percentage of residents with internet access is much higher than in LEDCs. Indeed, one of the major problems in preparing for a strike in an LEDC is communicating with the people in an area that is likely to be affected as the infrastructure may well be poorly developed.

Most countries affected by tropical storms now have education programmes to raise awareness on preparing for storms. There is an annual Leaflets, posters and school lessons are common ways of spreading the message. New technologies - such as Twitter (see link below) are also being used to educate people. Hurricane Preparedness Week in the USA when schools, businesses and families are all encouraged to pland for possible strikes in the forthcoming hurricane season.

The video clip below is a Public Service Announcement by Governor Haley Barbour encouraging people to get ready for the hurricane season.

People living in areas affected by tropical storms are encouraged to have a hurricane emergency kit on standby and also to have thought in advance about how they will protect their home and belongings. This might include boarding up windows and doors. In MEDCS, people may also be able to afford windproof tiles, water-resistant windows and strengthened building structures.

Act
People in LEDCs may not be able to afford this kind of protection. However, simple but cheap measures can be put in place to ensure that people are well prepared for tropical storms. These include educating people (particularly women) about what to wear in case they have to swim, building homes on stilts, building cyclone shelters and training local people to organise others in an evacuation.

When landfall has been forecast, action needs to be taken. This might include boarding up windows and doors, or evacuating the area. A mandatory evacuation is where the authorities command everyone in an area to leave. It is vital to ensure that only those peole who are in the danger area try to leave - otherwise the road system will get clogged up and people will be put at greater risk.

Useful weblinks:
FEMA guidance on how to prepare for a hurricane
Twitter account for Atlantic Watch - keep up to date with forecasts and tips for preparing your home to survive a hurricane strike (unoffical Twitter for NHC)

Hurricane Strike! - a superb website with lots of interactives and simulations about preparing for a hurricane strike - user account required (free to sign up)

Stop Disasters! - an online game about preparing for a tropical storm

Learning objectives:

- to recognise that scientists are still debating whether or not the distribution and frequency of tropical storms may change

- to be able to give reasons and evidence in support of the argument that global warming is increasing the number of storms

- to be able to explain the argument that there is a natural cycle

- to learn how to make an informed judgment as to whether or not the number and severity of tropical storms is changing
Why are opinions divided?
This is a controversial issue! Scientists are not agreed about how and why the distribution of tropical storms might change. The exam specification says that you must be able to 'explain why the distribution and frequency of tropical storms may change' and that you should include the impact of climate change in your explanation. However, as good geographers you will need to keep an open mind as to whether or not climate change is really at the heart of any changes to the intensity and distribution of tropical storms.
Why do people think that climate change will lead to more tropical storms?
Satellite technology has only been used to monitor tropical storms since the late 1960s. Before this, accounts from ships' logs, aeroplane research flights, and simple weather recording instruments were used. Some scientists have argued that the number and strength of tropical storms in the pst may have been greater than was actually recorded at the time. They also cliam that there may have been some tropical storms occurring that we did not know about as they did not make landfall. The graph below shows the storm history of named tropical storms in the North Atlantic. It is divided into two periods - pre-satellites and post-satellites. Do you think that the number of storms is increasing?

As you already know, tropical storms form where the temperature of the water exceeds 27 degrees. Global warming is causing a rise in the ocean temperatures, and this will mean that ocean temperatures will exceed 27 degrees for longer periods of time. As a result, the tropical storm season will last longer. In addition, ocean temperatures will exceed 27 degrees in more places so there will be more tropical storms.

The map below shows the monthly sea surface temperature anomalies in January 2010 relative to the 1961-1990 base period.
The 'natural cycle' viewpoint

An alternative viewpoint is that there is a natural cycle of variations in the number of tropical storms and that this is not linked to global warming. A natural cycle is a series of events that happen over and over again. the AMO is a 20-20 year fluctuation between warmer and cooler than average ocean temperatures in the North Atlantic Ocean. We are currently in the warm phase of the AMO. Some scientists argue that this is why we are experiencing increased tropical storm activity. The graph below shows a clear cyclical pattern in AMO values.
Are tropical storms becoming more destructive?

In terms of the damage they cause, tropical storms do seem to be getting more destructive. 6 out of the 10 costliest hurricanes in the USA have happened since 1990. Why might this be?
El Nino
Firstly, more people are living near the coast. As tropical storms' effects are concentrated in coastal areas, this means that more people are living in danger zones. There has been much more buidling in these aeas in recent years - so when a hurricane strikes, there is more infrastructure in its way and for it to damage! The value of property at the coast has increased rapidly, so the costs of clear-up have increased too.

El Niño is a climate phenomenon affecting the Pacific, Atlantic and Indian Oceans, occurring approx every 3-7 years. Officially, it is a sustained sea surface temperature greater than 0.5°C more than normal across the central tropical Pacific Ocean. It is explained very clearly on the BBC Bitesize website - so please click here for more infomation. Thanks also to Slideshare user MissM for the PowerPoint embedded below. They are both far better explanations than I would be able to give you.

Normally, trade winds blow west and slightly north across the Pacific Ocean, causing surface water, warmed by the sun, to 'pile up' at the western end so that the sea surface is about half a metre higher here. The warm water means surface temperature is about 8 degrees higher. Sometimes the normal trade winds relax. This is the start of an El Niño. The warm pool of water in the Western Pacific is released. It 'floats' because it is less dense than the cold water around it, and flows across the surface of the ocean back east towards South America.

In general, El Nino events are characterised by more tropical storms in the eastern Pacific and less in the Atlantic, Gulf of Mexico and Caribbean Sea. This is shown in the table below.
Exam Question
There is some uncertainty as to what will happen to El Nino as the planet warms. 3-5 million years ago the carbon dioxide in the atmosphere was significantly higher than it is now. During this time the El Niño conditions we consider exceptional now were much more frequent, perhaps even normal. The Met Office has suggested than an increase in carbon dioxide in the atmosphere will increase the frequency and intensity of El Niño. This may well be a cause of an increase in global sea surface temperatures.

The specimen exam paper for Unit 2 includes a graph about the number of tropical storms. Candidiates are asked to describe the changes to the average number of tropical storms in the Atlantic Ocean between 1900-2005 (3 marks) and give reasons for this pattern (4 marks). The graph is shown below. You should try to answer this question. Allow yourself 8 minutes to complete your answer.

The first question (the describe part) is point-marked. You have to make 3 good points to get your 3 marks. You need to include figures from the graph in your description. Here are some things that you could write:

- Between 1900-1930 there was a low average number of storms (less than 10 per year)

- Between 1930-1990, the average number of storms increased slightly, fluctuating around 10 per year (between 9 and 11.5)

- Between 1990-2005, the average number of storms increased significantly and was greater than 10 storms per year throughout the period, reaching 15 per year by 2005

The second question (the explain part) is also point-marked. You can either make 4 good separate points, or 2 points that you expand on. Here are some ideas from the mark scheme:
How did you do?
Reference to global warming/climate change (1) + effects (1), e.g. Due to global warming (1), there has been a rise in sea-surface temperatures (1) which means that more storms go on to become major hurricanes (1) because there are longer periods when the temperatures exceed 27°C (1).

Useful weblinks:

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Unit 2 Section C - Causes and effects of tropical storms and responses to them

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to know what a tropical storm is - to be able to explain the physical processes leading to the formation of a tropical storm - to be able to describe the locations in which we find tropical storms - to know how the Saffir-Simpson scale is used to classify tropical storms Note: Depending on where you are in the world, you may call these weather systems by a different name.

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Yellowstone volcano: What would happen if Yellowstone erupted

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About 1,500 active volcanoes can be found around the world. Learn about the major types of volcanoes, the geological process behind eruptions, and where the most destructive volcanic eruption ever witnessed occurred.

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Volcanoes are Earth's geologic architects. They've created more than 80 percent of our planet's surface, laying the foundation that has allowed life to thrive. Their explosive force crafts mountains as well as craters. Lava rivers spread into bleak landscapes. But as time ticks by, the elements break down these volcanic rocks, liberating nutrients from their stony prisons and creating remarkably fertile soils that have allowed civilizations to flourish.

There are volcanoes on every continent, even Antarctica. Some 1,500 volcanoes are still considered potentially active around the world today; 161 of those-over 10 percent-sit within the boundaries of the United States.

But each volcano is different. Some burst to life in explosive eruptions, like the 1991 eruption of Mount Pinatubo, and others burp rivers of lava in what's known as an effusive eruption, like the 2018 activity of Hawaii's Kilauea volcano. These differences are all thanks to the chemistry driving the molten activity. Effusive eruptions are more common when the magma is less viscous, or runny, which allows gas to escape and the magma to flow down the volcano's slopes. Explosive eruptions, however, happen when viscous molten rock traps the gasses, building pressure until it violently breaks free.

How do volcanoes form?

The majority of volcanoes in the world form along the boundaries of Earth's tectonic plates-massive expanses of our planet's lithosphere that continually shift, bumping into one another. When tectonic plates collide, one often plunges deep below the other in what's known as a subduction zone.

As the descending landmass sinks deep into the Earth, temperatures and pressures climb, releasing water from the rocks. The water slightly reduces the melting point of the overlying rock, forming magma that can work its way to the surface-the spark of life to reawaken a slumbering volcano.

Not all volcanoes are related to subduction, however. Another way volcanoes can form is what's known as hotspot volcanism. In this situation, a zone of magmatic activity-or a hotspot-in the middle of a tectonic plate can push up through the crust to form a volcano. Although the hotspot itself is thought to be largely stationary, the tectonic plates continue their slow march, building a line of volcanoes or islands on the surface. This mechanism is thought to be behind the Hawaii volcanic chain.

Where are all these volcanoes?

Some 75 percent of the world's active volcanoes are positioned around the ring of fire, a 25,000-mile long, horseshoe-shaped zone that stretches from the southern tip of South America across the West Coast of North America, through the Bering Sea to Japan, and on to New Zealand.

This region is where the edges of the Pacific and Nazca plates butt up against an array of other tectonic plates. Importantly, however, the volcanoes of the ring aren't geologically connected. In other words, a volcanic eruption in Indonesia is not related to one in Alaska, and it could not stir the infamous Yellowstone supervolcano.

What are some of the dangers from a volcano?

Volcanic eruptions pose many dangers aside from lava flows. It's important to heed local authorities' advice during active eruptions and evacuate regions when necessary.

One particular danger is pyroclastic flows, avalanches of hot rocks, ash, and toxic gas that race down slopes at speeds as high as 450 miles an hour. Such an event was responsible for wiping out the people of Pompeii and Herculaneum after Mount Vesuvius erupted in A.D. 79.

Similarly, volcanic mudflows called lahars can be very destructive. These fast-flowing waves of mud and debris can race down a volcano's flanks, burying entire towns.

Ash is another volcanic danger. Unlike the soft, fluffy bits of charred wood left after a campfire, volcanic ash is made of sharp fragments of rocks and volcanic glass each less than two millimeters across. The ash forms as the gasses within rising magma expand, shattering the cooling rocks as they burst from the volcano's mouth. It's not only dangerous to inhale, it's heavy and builds up quickly. Volcanic ash can collapse weak structures, cause power outages, and is a challenge to shovel away post-eruption.

Can we predict volcanic eruptions?

Volcanoes give some warning of pending eruption, making it vital for scientists to closely monitor any volcanoes near large population centers. Warning signs include small earthquakes, swelling or bulging of the volcano's sides, and increased emission of gasses from its vents. None of those signs necessarily mean an eruption is imminent, but they can help scientists evaluate the state of the volcano when magma is building.

However, it's impossible to say exactly when, or even if, any given volcano will erupt. Volcanoes don't run on a timetable like a train. This means it's impossible for one to be "overdue" for eruption -no matter what news headlines say.

What is the largest eruption in history?

The deadliest eruption in recorded history was the 1815 explosion of Mount Tabora in Indonesia. The blast was one of the most powerful ever documented and created a caldera -essentially a crater-4 miles across and more than 3,600 feet deep. A superheated plume of hot ash and gas shot 28 miles into the sky, producing numerous pyroclastic flows when it collapsed.

The eruption and its immediate dangers killed around 10,000 people. But that wasn't its only impact. The volcanic ash and gas injected into the atmosphere obscured the sun and increased the reflectivity of Earth, cooling its surface and causing what's known as the year without a summer. Starvation and disease during this time killed some 82,000 more people, and the gloomy conditions are often credited as the inspiration for gothic horror tales, such as Mary Shelley's Frankenstein.

Although there have been several big eruptions in recorded history, volcanic eruptions today are no more frequent than there were a decade or even a century ago. At least a dozen volcanoes erupt on any given day. As monitoring capacity for-and interest in-volcanic eruptions increases, coverage of the activity more frequently appears in the news and on social media. As Erik Klemetti, associate professor of geosciences at Denison University, writes in The Washington Post: "The world is not more volcanically active, we're just more volcanically aware."

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Volcanoes are Earth's geologic architects. They've created more than 80 percent of our planet's surface, laying the foundation that has allowed life to thrive. Their explosive force crafts mountains as well as craters. Lava rivers spread into bleak landscapes.

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BBC - GCSE Bitesize: Effects of volcanic eruptions

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A secondary school revision resource for GCSE Geography covering key facts about volcanoes and volcanic eruptions.

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Home " Volcanoes " Volcanic Hazards

Many types of hazards are associated with volcanoes

Article by Jessica Ball

Volcanic Hazards

Volcanoes can be exciting and fascinating, but also very dangerous. Any kind of volcano is capable of creating harmful or deadly phenomena, whether during an eruption or a period of quiescence. Understanding what a volcano can do is the first step in mitigating volcanic hazards, but it is important to remember that even if scientists have studied a volcano for decades, they do not necessarily know everything it is capable of. Volcanoes are natural systems, and always have some element of unpredictability.

Volcanologists are always working to understand how volcanic hazards behave, and what can be done to avoid them. Here are a few of the more common hazards, and some of the ways that they are formed and behave. (Please note that this is intended as a source of basic information only, and should not be treated as a survival guide by those who live near a volcano. Always listen to the warnings and information issued by your local volcanologists and civil authorities.)

Table of Contents

Lava Flows

Lava is molten rock that flows out of a volcano or volcanic vent. Depending on its composition and temperature, lava can be very fluid or very sticky (viscous). Fluid flows are hotter and move the fastest; they can form streams or rivers, or spread out across the landscape in lobes. Viscous flows are cooler and travel shorter distances, and can sometimes build up into lava domes or plugs; collapses of flow fronts or domes can form pyroclastic density currents (discussed later).

Most lava flows can be easily avoided by a person on foot, since they don't move much faster than walking speed, but a lava flow usually cannot be stopped or diverted. Because lava flows are extremely hot - between 1,000-2,000°C (1,800 - 3,600° F) - they can cause severe burns and often burn down vegetation and structures. Lava flowing from a vent also creates enormous amounts of pressure, which can crush or bury whatever survives being burned.

Pyroclastic Density Currents

Pyroclastic Density Currents

Pyroclastic density currents are an explosive eruptive phenomenon. They are mixtures of pulverized rock, ash, and hot gases, and can move at speeds of hundreds of miles per hour. These currents can be dilute, as in pyroclastic surges, or concentrated, as in pyroclastic flows. They are gravity-driven, which means that they flow down slopes.

A pyroclastic surge is a dilute, turbulent density current that usually forms when magma interacts explosively with water. Surges can travel over obstacles like valley walls, and leave thin deposits of ash and rock that drape over topography. A pyroclastic flow is a concentrated avalanche of material, often from a collapse of a lava dome or eruption column, which creates massive deposits that range in size from ash to boulders. Pyroclastic flows are more likely to follow valleys and other depressions, and their deposits infill this topography. Occasionally, however, the top part of a pyroclastic flow cloud (which is mostly ash) will detach from the flow and travel on its own as a surge.

Pyroclastic density currents of any kind are deadly. They can travel short distances or hundreds of miles from their source, and move at speeds of up to 1,000 kph (650 mph). They are extremely hot - up to 400°C (750°F). The speed and force of a pyroclastic density current, combined with its heat, mean that these volcanic phenomena usually destroy anything in their path, either by burning or crushing or both. Anything caught in a pyroclastic density current would be severely burned and pummeled by debris (including remnants of whatever the flow traveled over). There is no way to escape a pyroclastic density current other than not being there when it happens!

One unfortunate example of the destruction caused by pyroclastic density currents is the abandoned city of Plymouth on the Caribbean island of Montserrat. When the Soufrière Hills volcano began erupting violently in 1996, pyroclastic density currents from eruption clouds and lava dome collapses traveled down valleys in which many people had their homes, and inundated the city of Plymouth. That part of the island has since been declared a no-entry zone and evacuated, although it is still possible to see the remains of buildings which have been knocked over and buried, and objects that have been melted by the heat of the pyroclastic density currents.

Pyroclastic Falls

Pyroclastic falls, also known as volcanic fallout, occur when tephra - fragmented rock ranging in size from mm to tens of cm (fractions of inches to feet) - is ejected from a volcanic vent during an eruption and falls to the ground some distance away from the vent. Falls are usually associated with Plinian eruptive columns, ash clouds or volcanic plumes. Tephra in pyroclastic fall deposits may have been transported only a short distance from the vent (a few meters to several km), or, if it is injected into the upper atmosphere, may circle the globe. Any kind of pyroclastic fall deposit will mantle or drape itself over the landscape, and will decrease in both size and thickness the farther away it is from its source.

Tephra falls are usually not directly dangerous unless a person is close enough to an eruption to be struck by larger fragments. The effects of falls can be, however. Ash can smother vegetation, destroy moving parts in motors and engines (especially in aircraft), and scratch surfaces. Scoria and small bombs can break delicate objects, dent metals and become embedded in wood. Some pyroclastic falls contain toxic chemicals that can be absorbed into plants and local water supplies, which can be dangerous for both people and livestock. The main danger of pyroclastic falls is their weight: tephra of any size is made up of pulverized rock, and can be extremely heavy, especially if it gets wet. Most of the damage caused by falls occurs when wet ash and scoria on the roofs of buildings causes them to collapse.

Pyroclastic material injected into the atmosphere may have global as well as local consequences. When the volume of an eruption cloud is large enough, and the cloud is spread far enough by wind, pyroclastic material may actually block sunlight and cause temporary cooling of the Earth's surface. Following the eruption of Mount Tambora in 1815, so much pyroclastic material reached and remained in the Earth's atmosphere that global temperatures dropped an average of about 0.5 °C (~1.0 °F). This caused worldwide incidences of extreme weather, and led 1816 to be known as 'The Year Without A Summer.'

Lahars

Lahars are a specific kind of mudflow made up of volcanic debris. They can form in a number of situations: when small slope collapses gather water on their way down a volcano, through rapid melting of snow and ice during an eruption, from heavy rainfall on loose volcanic debris, when a volcano erupts through a crater lake, or when a crater lake drains because of overflow or wall collapse.

Lahars flow like liquids, but because they contain suspended material, they usually have a consistency similar to wet concrete. They flow downhill and will follow depressions and valleys, but they can spread out if they reach a flat area. Lahars can travel at speeds of over 80 kph (50 mph) and reach distances dozens of miles from their source. If they were generated by a volcanic eruption, they may retain enough heat to still be 60-70°C (140-160°F) when they come to rest.

Lahars are not as fast or hot as other volcanic hazards, but they are extremely destructive. They will either bulldoze or bury anything in their path, sometimes in deposits dozens of feet thick. Whatever cannot get out of a lahar's path will either be swept away or buried. Lahars can, however, be detected in advance by acoustic (sound) monitors, which gives people time to reach high ground; they can also sometimes be channeled away from buildings and people by concrete barriers, although it is impossible to stop them completely.

Gases

Volcanic gases are probably the least showy part of a volcanic eruption, but they can be one of an eruption's most deadly effects. Most of the gas released in an eruption is water vapor (H 2O), and relatively harmless, but volcanoes also produce carbon dioxide (CO 2), sulfur dioxide (SO 2), hydrogen sulfide (H 2S), fluorine gas (F 2), hydrogen fluoride (HF), and other gases. All of these gases can be hazardous - even deadly - in the right conditions.

Carbon dioxide is not poisonous, but it displaces normal oxygen-bearing air, and is odorless and colorless. Because it is heavier than air, it collects in depressions and can suffocate people and animals who wander into pockets where it has displaced normal air. It can also become dissolved in water and collect in lake bottoms; in some situations, the water in those lakes can suddenly 'erupt' huge bubbles of carbon dioxide, killing vegetation, livestock and people living nearby. This was the case in the overturn of Lake Nyos in Cameroon, Africa in 1986, where an eruption of CO 2 from the lake suffocated more than 1,700 people and 3,500 livestock in nearby villages.

Sulfur dioxide and hydrogen sulfide are both sulfur-based gases, and unlike carbon dioxide, have a distinct acidic, rotten-egg smell. SO 2 can combine with water vapor in the air to form sulfuric acid (H 2SO 4), a corrosive acid; H 2 S is also very acidic, and extremely poisonous even in small amounts. Both acids irritate soft tissues (eyes, nose, throat, lungs, etc.), and when the gases form acids in large enough quantities, they mix with water vapor to form vog, or volcanic fog, which can be dangerous to breathe and cause damage to the lungs and eyes. If sulfur-based aerosols reach the upper atmosphere, they can block sunlight and interfere with ozone, which have both short and long-term effects on climate.

One of the nastiest, although less common gases released by volcanoes is fluorine gas (F 2). This gas is yellowish brown, corrosive and extremely poisonous. Like CO 2, it is denser than air and tends to collect in low areas. Its companion acid, hydrogen fluoride (HF), is highly corrosive and toxic, and causes terrible internal burns and attacks calcium in the skeletal system. Even after visible gas or acid has dissipated, fluorine can be absorbed into plants, and may be able to poison people and animals for long periods following an eruption. After the 1783 eruption of Laki in Iceland, fluorine poisoning and famine caused the deaths of more than half the country's livestock and almost a quarter of its population.

Volcanic Hazard Resources

Bardintzeff, J.-M. and McBirney, A.R., 2000, Volcanology: Massachusetts, Jones & Bartlett Publishers, 268 p.

Schminke, H.-U., 2004, Volcanism: Berlin, Springer, 324 p.

McNutt, S.R., Rymer, H., and Stix, J. (editor), 1999, Encyclopedia of Volcanoes: San Diego, CA Academic Press, 1456 p.

Gates, A.E. and Ritchie, D., 2007, Encyclopedia of Earthquakes and Volcanoes, Third Edition: New York, NY, Checkmark Books, 346 p.

About the Author

Jessica Ball is a graduate student in the Department of Geology at the State University of New York at Buffalo. Her concentration is in volcanology, and she is currently researching lava dome collapses and pyroclastic flows. Jessica earned her Bachelor of Science degree from the College of William and Mary, and worked for a year at the American Geological Institute in the Education/Outreach Program. She also writes the Magma Cum Laude blog, and in what spare time she has left, she enjoys rock climbing and playing various stringed instruments.

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Greece wildfires: '60 dead' in holiday area - BBC News

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In the past two decades, the number of Americans at risk of experiencing a wildfire has doubled. Learn what you need to do if one is near you.

In the wake of Maui's deadly wildfires-where many died, and a historic town once known as the capital of Hawaii's monarchy was destroyed-residents and tourists are reeling from the damage.

The fires that burned through the island were worsened by intense winds from a nearby hurricane and drought conditions. Some experts have also said invasive grasses not native to the island created more flammable conditions that fed the fire's flames. Hawaii is not historically known for wildfires, but-like many parts of the world-is seeing more intense fires because of climate change and mismanaged land.

Wildfires can burn millions of acres of land at shockingly fast speeds, consuming everything in their paths. These rolling flames travel up to 14 miles an hour, which converts to about a four-minute-mile pace, and can overtake the average human in minutes.

Destruction caused by wildfires in the United States has significantly increased in the last two decades. An average of 72,400 wildfires cleared an average of 7 million acres of U.S. land each year since 2000, double the number of acres scorched by wildfires in the 1990s. In 2015, the largest wildfire season recorded in U.S. history burned more than 10 million acres of land.

Because much of the U.S. is expected to get hotter and drier with climate change, wildfire risk is generally expected to rise. At the same time, as the population in the United States rises and people increasingly move into rural and wilderness areas, more homes and other structures are likely to be placed in harm's way.

That's why it's critical to understand how wildfires get started, how to stop them, and what to do when they occur.

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How wildfires start

Though they are classified by the Environmental Protection Agency as natural disasters, only 10 to 15 percent of wildfires occur on their own in nature. The other 85 to 90 percent result from human causes, including unattended camp and debris fires, discarded cigarettes, and arson.

Naturally occurring wildfires can spark during dry weather and droughts. In these conditions, normally green vegetation becomes bone-dry, flammable fuel; strong winds spread fire quickly; and warm temperatures encourage combustion. With these ingredients, the only thing missing is a spark-in the form of lightning, arson, a downed power line, or a burning campfire or cigarette-to wreak havoc.

Firefighters battle the Woolsey Fire in Malibu, California, on November 12, 2018. That blaze burned nearly 97,000 acres in Southern California, killing three people and damaging an estimated $6 billion in property.

Photograph by Eric Thayer, Reuters

Natural or man-made, three conditions must be present for a wildfire to burn: fuel, oxygen, and a heat source. Firefighters call these three elements the fire triangle.

Fuel is any flammable material surrounding a fire, including trees, grasses, brush, even homes. The greater an area's fuel load, the more intense the fire is likely to be. The most wildfire-prone state is California, which lost 2,569,386 acres of land to 7,396 wildfires in 2021.

Air supplies the oxygen a fire needs to burn. California wildfires are often made worse by the hot, dry Santa Ana winds, which can carry a spark for miles. In Hawaii, Hurricane Dorian's winds helped feed the flames burning on Maui.

Heat sources help spark the wildfire and bring fuel to temperatures hot enough to ignite. Lightning, burning campfires or cigarettes, and even the sun can all provide sufficient heat to spark a wildfire.

Violent infernos are most common in the western states, where heat, drought, and frequent thunderstorms create ripe conditions. Montana, Idaho, Wyoming, Washington, Colorado, Oregon, and California experience some of the worst conflagrations. Wildfires also occur around the world and in most of the 50 states.

How they are stopped

Firefighters battle blazes by depriving them of one or more of the fire triangle fundamentals. One traditional method is to douse existing fires with water and spray fire retardants. Firefighters also sometimes work in teams, often called hotshots, to clear vegetation from the land around a fire to contain and eventually starve it of fuel. The resulting tracts of land are called firebreaks.

Firefighters may also employ controlled burning, creating backfires, to stop a wildfire. This method involves fighting fire with fire. These prescribed-and controlled-fires remove undergrowth, brush, and litter from a forest, depriving an otherwise raging wildfire of fuel.

Benefits of wildfires

Although they can be dangerous to humans, naturally occurring wildfires play an integral role in nature. By burning dead or decaying matter, they can return otherwise trapped nutrients to the soil. They also act as a disinfectant, removing disease-ridden plants and harmful insects from an ecosystem.

High winds and hot temperatures fanned a 1996 wildfire in the foothills around Boise, Idaho, into an inferno that burned for seven days. When it was finally extinguished, the outbreak-dubbed the Eighth Street Fire-had scorched some 15,000 acres (6,000 hectares) and stripped bare two of the region's major watersheds.

Photograph by Mark Thiessen

Wildfires thin forest canopies and undergrowth, allowing sunlight to reach the forest floor and a new generation of seedlings to grow. In fact, some species of trees, like sequoias, rely on fire for their seeds to even open.

In Hawaii, however, invasive grasses not native to the state may have worsened Maui's fires. This flammable grass now covers about a quarter of Hawaii's total land area, and the average area burned by wildfires has grown 400 percent in the past 100 years, according to the Hawaii Wildfire Management Organization.

What to do in a wildfire

Wildfires devastate anything in their path. And while they are difficult to stop, there are many steps people can take before, during, and after wildfires to limit their damage.

Before:

If you know a wildfire is traveling toward your area, the best thing to do is leave. Immediately.

If you live in a fire-prone area, it's best to prepare ahead of time. Have an evacuation plan in mind and a "go bag" with emergency supplies already packed during fire season.

Trim brush, weeds, and other potential fuels on your property, especially around your home.

Put away grills, propane tanks, or other flammable materials that may be in your yard.

Close all doors and windows and fill sinks, tubs, and other containers with water to discourage fire.

Shut off natural gas, propane, or fuel oil supplies.

When you purchase a home in a wildfire-prone area, avoid neighborhoods on slopes that are steep or barren, suggests the California Chaparral Institute. Although some people fear that houses near shrubs are more likely to burn, that's not necessarily the case, the institute says. Rather, a landscape without vegetation can be the perfect runway for winds to bring embers, which are one of the biggest threats to homes during a wildfire.

Wetting your roof may help reduce the risk of airborne embers catching, says the California Chaparral Institute. In fact, some people in fire-prone areas even install rooftop sprinklers for that purpose.

If you cannot leave as a fire approaches, dial 911. Then don an N95 respirator to help reduce smoke and particle inhalation.

During:

Listen for emergency alerts.

Stay inside. Go to the safest building or room with the lowest smoke levels. Crouch low for the best air. If you don't have a mask, breathe through a wet cloth.

If you are caught outside, try to find a body of water to crouch in. If you can't, find a depression with the least vegetation and lie low, covering yourself with wet blankets, clothes, or soil if possible.

After:

Do not return until instructed to do so.

Listen to authorities before drinking water from the area.

Avoid items that are hot, smoky, or charred.

Text friends and family, but don't call. Lines may be busy.

Wear a dust mask and document property damage.

Beware of the risk of flooding, since trees and protective vegetation might have been removed, exposing loose soil.

This article originally published in August 2019 and has been updated with new information.

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What caused Maui's wildfires to move shockingly fast? Here's what we know.

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In the past two decades, the number of Americans at risk of experiencing a wildfire has doubled. Learn what you need to do if one is near you.

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At least 80 people have been killed in wildfires in Greece, with blazes also reported as far apart as the US, Sweden, Canada and the UK. It's a summer that has seen an unusually high number of fires in some countries.

Worldwide, an area equivalent to about 20 times the size of Great Britain is burnt by wildfires in a typical year.

Most are in remote areas such as the savannah grasslands of Africa and South America, or the boreal forests which stretch from western Alaska to eastern Siberia.

But we rarely hear about wildfires in such isolated places. It tends to be those which threaten lives, infrastructure, or natural resources that hit the headlines.

Indeed, in Europe, the number of fires so far this year is well above average - but not in the countries which are usually worst affected.

There were 427 blazes between 1 January and 24 July, compared with an average of 298 for the same period in the past decade.

But, very importantly, the area they burned is only about half what is usually seen - 55,700 hectares, compared with 112,000 hectares.

In the US, the number of fires this year is slightly below average. However, there has been a small increase in the area burned, from just over 1.4m hectares to almost 1.6m hectares.

The most important change is not how many fires there have been, but where they are burning. The north-west of Europe is experiencing a rare heatwave.

This has brought unusually dry conditions which have allowed large fires in regions which usually see very few.

In the UK the area burned so far - 13,888 hectares - is more than four times the average of the past decade. The fires have included an area of peatland near Manchester and grassland in London.

In Sweden, the figure, 18,500 hectares, is an astounding 41 times the 10-year average. Dozens of fires have burned from the Arctic Circle down to the Baltic Sea.

Other northern European countries including Denmark, Estonia, Finland, Germany and Latvia have seen between 20 and 200 times the normal area burned.

In contrast, Mediterranean Europe - which usually sees a large number of fires - has had a relatively cool and wet spring and early summer.

In Italy and Croatia the area burned is well below average.

Spain and Portugal, which normally have fire damage over a greater area than any other European countries, have suffered relatively few fires - with only 12% and 5% of the average area burned, respectively.

However, fire season is not over and there is a danger that strong vegetation growth in parts of the Mediterranean may fuel fires later in the coming months.

While no single factor explains hot weather around the world, experts say climate change is bringing greater and more frequent weather extremes.

It is not that the 2018 fires in the UK and Sweden will be the "new normal", but they may be more common.

Higher temperatures worldwide increase the risk of wildfires in many regions, but other factors are also important.

To explain fire, scientists and firefighters use something called the "fire triangle": an ignition source, plus fuel such as dry vegetation and oxygen to keep going.

Wildland firefighters also use the "30-30-30 rule" under which extreme fire conditions are expected when temperatures are above 30C, relative humidity is below 30% and winds are greater than 30km per hour (18.6 mph).

Drought-stricken vegetation, such as the Swedish forests and the British moorlands, catches and carries fire more easily than it would in a wetter year.

In other words, there is more "fuel" available when the vegetation is dry.

Oxygen is readily available in the air - particularly when wind fans the fires.

And sources of ignition are plentiful where there are people, whether that is a campfire, a spark from a power line, or arson.

Natural ignition by lightning is common in some regions, such as the North America boreal forest, but in Europe the vast majority of fires are human-caused.

The deadly fires in Greece are a prime example of weather being only one important factor.

Until a few days ago, Greece had experienced fewer fires than is typical.

But, in a densely-populated region near Athens, the presence of villages and towns amid highly-flammable pine forests and shrubland has had tragic consequences.

Increase of "megafires"

Sadly, such events have happened before.

More than 100 people were killed by wildfires in Portugal only last year and 173 people died in the Black Saturday Fires in Australia in 2009.

In recent decades, there has been an increase of "megafires".

These are too big and fierce to be stopped, irrespective of the efforts and resources thrown at them.
More like this
While climate change may have made more fuel available for such fires, human behaviour has also played a role.

In many rural areas of Europe land has been abandoned - leading to the growth of more vegetation close to and among homes. People often enjoy living or holidaying in forest areas, which also increases the risk of being directly affected by fire.

Fortunately, it is possible to reduce the risks this poses - by clearing "fuel" close to buildings and building fire shelters in areas where the population might need them.

Educating people about the risks and having evacuation plans in place can also reduce the threat to human lives and the economy.

We need to adapt and learn how to coexist with fire.

Fire has been transforming the Earth's landscapes and vegetation for millions of years.

It is not going to go away.
About this piece
This analysis piece was commissioned by the BBC from experts working for an outside organisation.

Prof Stefan H. Doerr is a geography professor at Swansea University and editor-in-chief of the International Journal of Wildland Fire.

Dr Cristina Santín is senior lecturer and research fellow in the biosciences department at Swansea University.

Edited by Duncan Walker

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Why wildfires are breaking out in the 'wrong' countries

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At least 80 people have been killed in wildfires in Greece, with blazes also reported as far apart as the US, Sweden, Canada and the UK. It's a summer that has seen an unusually high number of fires in some countries.

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tectonic hazards
what are they?

June 1991 Mount Pinatubo eruption - the eruption reduced global temperatures in 1992.

Tectonic hazards are hazard events caused by tectonic plates colliding into each other, moving against each other, moving apart or subduction between a less dense plate and a more dense plate.

Examples of tectonic hazards include:

Volcanoes - these occur when hot magma is forced to the Earth's surface through fissures and cracks in the Earth's crust.

Earthquakes - these most commonly occur when two tectonic plates move against each other. Rocks break underground at the centre of the earthquake, and then the Earth's crust shakes when energy is released.

Tsunamis - caused by the rapid displacement of water.

Tropical cyclones - rapidly rotating storm with a low-pressure centre, spiral arrangement of thunderstorms and strong winds.

There is a distinct difference between the labelling of natural hazards and disasters.
Natural hazard - a natural event with the potential to harm people and their property.

Natural disaster - the realisation and impacts of a natural hazard (injuries, deaths, disruption and damage).

The two key words in bold here make these definitions differ considerably. Essentially a hazard has the potential to harm and a disaster is the realisation of the hazard ie. that its actually happening.

hazard profiles

Hazard profiles are key to categorising and simplifying the risks associated with different hazards. It is a description and analysis of a specific type of local hazard event. It can be performed for each natural hazard.

The criteria which makes up a hazard profile includes frequency, speed of onset, duration.

This is an example of a hazard profile for California's natural hazards. It lists all of the hazards that affect California and profiles each event according to the four characteristics important in analysing hazard events.

Profiling is important as it allows you to compare the physical processes and attributes that hazards share. It also allows decision makers and key players in terms of managing hazard able to simply understand where their efforts need to be targeted in terms of time and money.

This video goes through the structure of the Earth - this will help us to understand how the structure of the Earth effects the occurrence of tectonic hazards globally.

Significant geo-physical hazard events

Significant hydro-METEOROLOGICAL hazard events

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June 1991 Mount Pinatubo eruption - the eruption reduced global temperatures in 1992. Tectonic hazards are hazard events caused by tectonic plates colliding into each other, moving against each other, moving apart or subduction between a less dense plate and a more dense plate.