13.2 GROUP 2 To what extent is the impact of a volcanic eruption related to the type of eruption? (33 marks) by Miss Stewart

DISAGREE Marked by Amy

2024-11-21 15:32:56 UTC

The location of human settlements is more significant than the type of eruption in affecting the social and economic impacts of a volcanic eruption. If there are large towns or cities located near to a volcano, and it erupts, depending on the preparation of these people, many may die in lava flows, which are typical of every type of eruption, or they will be evacuated from their homes and lives so that they are safe. This evacuation has further impacts such as loss of income because people cannot go to work, disease spreads very quickly in evacuation camps, and also, having to leave their homes and possessions to be destroyed by the lava flows can cause PTSD. Furthermore, these settlements near to volcanoes can be destroyed completely by lava flows, resulting in people losing their homes, destroyed water supplies, and the destruction of businesses. The loss of businesses has many economic impacts including loss of exports and unemployment. In the 1995 Montserrat eruption, the capital city of Plymouth was decimated, including all the government buildings that had to be rebuilt in Little Bay, further reducing the economic development of the country. Overall, the presence of human settlements near to a volcano is the most important factor in the affecting the extent of the impacts of a volcanic eruption, because without their presence, there would be very few social or economic impacts. Whereas when they are nearby, there are catastrophic social and economic impacts, highlighting the significance of the location human settlements.

WWW: good case study knowledge, good at showing the further effects of evacuation. Well argued with lots of points

EBI: figures for how many people evacuated to show the extent of the impact numerically

Marker by Ollie

2024-11-25 17:48:55 UTC

When analysing the impacts of volcanic eruptions we have to categorise into three categories, the effects on the environment, economic effects and social effects. Type of eruption is at the heart of these impacts, whether it is a Hawaiian eruption (effusive) that its low viscous lava causes damage to terrestrial ecosystems and anything close to the source of the volcano, or Plinian and Vesuvian (explosive) eruptions causing ash clouds stopping air travel, and creating pyroclastic flows that destroy anything in its path at a rate of knots. Therefore it can be determined that type of eruption undoubtedly causes the biggest impact, compared to other factors such as the effect on human life and the geography of the location, because without the eruption types there would be no major impacts to document.

DISAGREE - marked by sam

2024-11-25 17:56:12 UTC

The geography of an area could be seen as a more significant impact than the type of the eruption because of the direct affect it has on the nature of the explosion. An example of this is a phreatomagmatic explosion. This is when hot magma rising up through a volcano comes into contact with ice causing it to solidify before shattering into fine ash. This occurred in the 2010 Eyjafjallajokull eruption, where the impact of this fine ash was seen globally as a result of the ash getting into the gulf stream which allowed it to travel across European air space cancelling over 95,000 flights in the 6 day air space ban and even having global implications, for example the Norwegian Prime Minister had to run office from New York. The impact of the volcano was not impactful because of the type of eruption, only 3 on the VEI scale, it was as a result of the ice cap covering the top of it which caused it to produce such fine ash which was able to travel into the gulf stream and therefore all over Europe. It can therefore be argued that the geography of an area could be seen as having a greater impact than the type of a eruption because, as seen with Eyjafjallajokull, it is able to directly influence the impact of the eruption. If it was not for the ice cap covering the volcano, the global, national and regional impact of the earthquake would have been significantly less as the volume of the ash, the size of it and therefore the distance it was able to travel would have been significantly reduced. This factor in determining the impact of an eruption suggests that it is not the type of eruption which has the greatest impact because no matter the type of eruption, the impact of it is altered by the geography of an area which is able to both mitigate or amplify the risk proposed and also directly change the type of eruption occurring.

Comments (Sam) - Extremely good AO1 knowledge, as shown by the phreatomagmatic eruption, VEI rating, and the amount of flights cancelled was impressive. The AO2 was well sprinkled in throughout, where the ranking was soldified.

EBI - The first line, what is meant by 'geography'? A bit vague. AO1 knowledge felt a bit overpowering and prevailing, but still good.

Agree

2024-11-26 22:17:21 UTC

Effusive eruptions typically have more localized and less severe impacts than explosive eruptions. They produce steady lava flows of low-viscosity basaltic lava, and release less gas into the atmosphere, with no ashfall. Effusive eruptions tend to have a higher frequency, with lava flows lasting months or even years, such as in Kilauea's 35 year eruption; these flows can devastate local communities by destroying infrastructure, homes, and agricultural land. Whilst lava flows can be deadly, they are relatively slow moving and easier to avoid than pyroclastic flows, posing a smaller risk to life. Although per eruption effusive may not have as great an effect, the constant output arguably impacts more people over time than a single eruption once every 10,000 years. With people living near effusive volcanoes such as in Hawaii permanently dealing with consequences of the eruptions. However, in contrast to explosive eruptions, effusive ones have very little impact beyond the local area. Iceland’s Eyjafjallajökull (E15) in 2010 formed an 8km high ash cloud- producing widespread ashfall, which can damage crops, ecosystems and infrastructure across a regional scale, as well having a significant impact on a global level, with flights, medical aid and political affairs across the world being delayed. The lack of ash to block sunlight and the reduced release of sulphur dioxide to reflect solar radiation also leads to effusive eruptions having a far smaller global cooling effect, proving any impact on climate change is almost entirely dependent on eruption type.

The new land formed by lava flows is composed of hard basaltic rock, which takes centuries to weather into fertile soil, making such areas less appealing for human settlement or agriculture, further reducing possible impact, in comparison to the rich fertile soils of explosive eruptions drawing in human civilization. Which potentially undermines the argument of location, if location of humans is affected by eruption type in the first place.

While effusive eruptions can frequently affect local landscapes and communities, they lack the far-reaching environmental and economic disruptions of explosive eruptions, such as E15’s global pause on air travel. This makes it evident that the type of eruption strongly defines its possible impact.

Agree - Anna - marked by lily and milly

2024-11-27 10:18:09 UTC

The type of eruption is arguably the largest factor contributing to the impact of a volcanic eruption, as explosive eruptions are far less localised. While effusive volcanic eruptions occur on a higher frequency, the smaller eruptions allow for planning against the volcano and sufficient evacuation plans, meaning that effusive volcanoes are not too impactful on civilisations. In comparison, explosive eruptions occur on a longer time frame due to their viscous lava that builds up pressure with trapped gas bubbles over time, which not only means that civilisations built around the volcano will not be as prepared for their catastrophic impacts, but the buildup of pressure within the volcano will only increase over time and release a more explosive eruption. For example, the Nevado del Ruiz eruption in Columbia had a devastating death toll of 23,000 people, due to the lack of education of the explosive volcano and its risks due to its 100 year dormancy. Another feature of explosive eruptions is the pyroclastic flow they produce. With a more explosive volcanic eruption, the subsequent pyroclastic flow will be more rapid as the volcanic material has been expelled faster upwards, and therefore has more momentum. Globally, the pyroclastic flow and ash clouds produced by explosive volcanoes have far wider-spread impacts than effusive volcanoes which are typically localised, and can cause detrimental effects to airlines and global travel. For example, this is shown by the 2010 Eyjafjallajokull (E15) eruption in Iceland, where ash clouds were produced by the phreatomagmatic eruptions that occurred when magma came into contact with the glacial ice, leading to violent explosions due to rapid cooling and expansion that sent a plume of volcanic ash over 8 km into the sky. This caused over 100,000 flights to be cancelled worldwide, and airlines lost 1.7 billion dollars in revenue. Not only do explosive volcanoes have a global impact, but also a large local impact. While the E15 eruption had no casualties, the eruption had a massive impact on the local environment, causing crop damage, infrastructure damage and altering the landscape. Explosive volcanoes not only cause detrimental global impacts (disrupting global economies like air travel) but also influence the local area massively, unlike effusive volcanoes that only cause local impacts. This highlights how the type of eruption is inextricably related to the extent of its impacts.

WWW. good AO2 points looking at spatial scale and comparison between types of eruptions , good case study detail

EBI. Could be more concise and could mention specific types of eruptions eg Plinian, Vesuvian etc.

2024-11-27 17:41:15 UTC

In conclusion, the type of eruption is the most significant factor in determining the impacts of a volcanic eruption due to the inherent differences between explosive and effusive eruptions.

Explosive eruptions are the most important as they cause widespread destruction, through Pyroclastic flows, lahars, and ash clouds disrupting global air traffic, as happened following the E15 eruption. Explosive eruptions can cause massive death tolls as a result. Effusive eruptions are significantly more localised, but can cause persistent impacts to the environment and infrastructure over time, as seen in Hawaii.

The location of human settlements is also significant as they amplify the social and economic impacts of a volcanic eruption, with densely populated areas putting more people and infrastructure at risk. However, the impact on settlements is dictated by the nature of the eruption. Without the eruptions characteristics, this risk would not exist, independent of whether the area immediate to a volcano is densely or sparsely populated.

The geography of a volcano can also significantly mediate the type and scale of impacts as a result of an eruption. Conditions unique to certain volcanoes, such as the ice cap on top of the E15 volcano in Iceland, can transform moderate eruptions into globally impactful events. However, can also act to mitigate volcanic hazards.

Therefore, despite the influence of geography and human settlement location, the type of eruption remains fundamental because it determines whether its impacts are local or global.