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Actividad de senderismo en el volcán Montaña Colorada (IES Las Maretas)

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Actividad de senderismo en el volcán Montaña Colorada (IES Las Maretas)

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How we will distinguish when a submarine volcano is going to erupt?

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How we will distinguish when a submarine volcano is going to erupt?

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Well, the latest researches assume that the colour of the ocean begin to change about a month before the submarine volcano will erupt. This suggests that ocean colour may be a reliable precursor of underwater volcanic activity. And, given this insight, there is every possibility that in the future, automated systems could analyse satellite images of the ocean in volcanic regions for signs of an impending eruption.

Sofia Christou, 1st Senior-High school of Kesariani

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In Santorini except for its known volcano on land, it also has an submarine volcano the name of which is Kolumbo. First and foremost this volcano is active and  was "discovered" when it breached the sea surface in 1649-50, but its explosion was not to be compared to the well-known Thera explosion and caldera collapse, currently dated in 1630 BC, with its devastating consequences for Minoan civilation.The 1650 explosion, occurred when the accumulating cone reached the surface, sent pyroclastic flows across the sea surface to the shores and slopes of Santorini, as a result about seventy people and many animals died. Plus, Kolumbo collapsed into its caldera,triggering a tsunami that caused damage on nearby islands up to 150 km distant.
Sofia Christou, 1st Senior-High school of Kesariani

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Submarine Kolumbo volcano, Santorini volcanic field, Greece (HCMR)

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In Greece there are over 73,000 volcanoes both active and inactive but very few active these days.Most people have probably heard of Santorini but the one in Nissiros is also worth visiting.

Thodoris.sid

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The active volcano of Methana,which is in Saronic Gulf,is very close to Athens.Its eruption,has changed the geological form of area's peninsula.It has 30 craters. The most famous of them , is in the northwest place of a village called "Poor country",but it is inactive.This crater has the depth of 50m , diameter of 100m and the highest point of cone is 425m. In the northeast of this volcano, we can discern 2 other parasitic craters. 1st Senior High School of Kessariani , Panagiota Tz.

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Vasiliki Trousa and Maria Stavridi 1st High School of Kaisariani
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When large volumes of magma are ejected over a short period of time, the volcano's magma chamber can become hollow and the ground surface above it is bound to collapse downward into the now empty magma chamber. The now sunken area where the volcano used to stand, is called a "caldera". The formation of a caldera is a rare event, that only a occurs a few times per century. One of the best-known and most frequently visited calderas is the Yellowstone Caldera, located in Yellowstone National Park, Wyoming, USA.

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Volcanoes in Greece⛰ Christina Stavrinaki 1st High School of Kesariani

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Volcanoes in Greece⛰ Christina Stavrinaki 1st High School of Kesariani

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Greece has most of its volcanoes extinct, however, there are some of them active. In total there are 10 active and extinct volcanoes. Only 5 of them are active which are in Milos, Methana, Sousaki, Nisyros and in Santorini and they receive  thousands of visitors every year. Santorinis volcano is the most famous with the largest caldera in the world!! Moreover, a strange phenomenon happens..Sea water fillsi ts caldera , where on the cliffs, small white houses are are built giving a dazzling view. The last eruption happened in 1950, but the volcano is still active. The second and the youngest volcano in Greece is located in Nisyros. Its only 160.000 years old. In 1888 the eruption formed a crater of 25m diameter! On the northeastern side of the Peloponnese , Methana, the volcanic activity started million years ago and it has 32 volcanoes that are mostly andesitic and dacitic lava domes . The last important volcano is located in Milos and its dormant as well. Greece also has other smaller volcanoes and in places where volcanoes extinct are found  thermal springs , with the most famous one called "Hot Springs" in Santorini.

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Maria Papakonstantinou 1st High School of Kaisariani

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Nisyros is one of several active volcanoes in Greece. Located in the Dodecanese, it’s a popular visitor attraction for those who come to visit on day trips from the holiday island of Kos. It is one of the ‘youngest’ volcanoes in the Mediterranean, with its crater only being created 160,000 years ago. Incredibly, you can walk right into the heart of it across the Lakki Plain(the town on Nisyros ).

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Volcanoes are Earth's geologic architect. They're create more than 80% of our planet's surface , laying the foundation that has allowed life to thrive . Their explosive force crafts mountains as well as creaters . Lava  rivers spread into bleak landscapes . But as times 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

How do volcanoes form?

Most volcanoes in the world form along the boundaries of Earth's tectonic plates- they are 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 meeting point of the overlying rock , forming magma that can work it's way to the surface- the spark of life that reawaken a slumbering volcano. But not all volcanoes are related to subduction, however. There is another way that volcanoes can form and it's called hotspot volcanism . In this situation, a zone of magmatic activity - or a  hotspot- in the middle of a tectonic plate continue their slow march , building a line of volcanoes or islands on the surface. This mechanism is though to be behind the Hawaii volcanic chain

1 st High school of Kaisariani
Iliana Stavropoulou

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In Greece, many islands were created by volcanic activity, which is fascinating, if we consider the effect they had in Greece's geography and history. Even though all of the volcanos are safe to visit, and open to tourists, most of them are still active.

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In Greece, many islands were created by volcanic activity, which is fascinating, if we consider the effect they had in Greece's geography and history. Even though all of the volcanos are safe to visit, and open to tourists, most of them are still active.

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Prassa evelina, 1st high school of Kaisariani

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Santorini’s volcano
Santorini is a Greek island that has its own volcano. It is the most famous volcano in Greece. In 1646 BC a massive volcanic eruption, perhaps one of the largest ever witnessed by mankind, took place in Santorini. Possibly as many as 20,000 people were killed as a result. The last eruption of the Santorini volcano was small and happened in 1950 and the volcano is still active.

Ioanna & George
1st High School of Kaisariani

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The volcano of Milos island is considered dormant. It is located in the center of the island and has given to Milos its richness in minerals and its strange geological formation. The last volcanic eruption on Milos took place in 90,000B.C. In places were volcanoes exist, there are also thermal springs.
Matina Haritou

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The Pacific Ring of Fire is an area in the Pacific Ocean stretching from South and North America to East Asia, Australia and New Zealand. 75% of the Earth's active and inactive volcanoes are concentrated here, where 90% of the world's earthquakes and 80% of the world's largest earthquakes originate. This is because the centre of the Pacific Ocean is where tectonic plates are born and are in permanent friction, accumulating tension. When this tension is released, it causes a tectonic plate movement underneath the other, triggering earthquakes that are felt by countries on the edge of the continents.

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CUMBRE VIEJA

Location: La Palma, Canary Islands.

Last eruption: since 19th September of 2021 until nowadays.

Type of location: hot spot.

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ETNA

Location: island of Silicy, Italy.

Last eruption: 21th September 2021 - nowadays.

Type of location: hot spot.

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FAGRADALSFJALL

Location: Iceland.

Last eruption: 19th March 2021 until nowadays.

Type of location: mid-ocean ridge.

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EL BOQUERÓN

Location: San Salvador.

Last eruption: June 1917 - November 1917.

Type of location: subduction zone (continental-oceanic convergence, Andean-type orogen).

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SAINT HELENS

Location: Washington, United States.

Last eruption: 18th May 1980.

Type of location: subduction zone.

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KILIMANJARO

Location: Tanzania.

Last eruption: 100.000 years ago.

Type of eruption: divergent edge.

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PINATUBO

Location: Luzon island, Philippines.

Last eruption: 2nd April 1991 until 15th June.

Type of location: subduction zone.

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KILAUEA

Location: Hawaii, United States.

Last eruption: 30th September 2021 - nowadays.

Type of location: hot spot.

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Little structures at the ocean's floor with little emissions that are not hot. It expells acids and mineral depositions.

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They are hot emissions around 400°C. They make chimneys about 10 m of height. They drop iron and sulfurous gases.

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Their temperature is below 100°C. They are made of water vapour.

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They are related to cold and their temperature arise until 100°C. They are made of water vapour.

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They are not as hot as dry volcanic gases. It's temperature is above 300-400 °C because they are expelled from supercial lavas. They are composed by acids.

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They are sent out in a fusion state. It's temperature is over 500 °C. They are made by sodium chloride without having water vapour.they can produce flames.

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This term is refering to a type of flow composed by incandescent fragments, hot gases and ash.

-Fiery clouds: they are a mixture of balmy volcanic gases, hot solid materials, and trapped air, which moves at a ground level and results from certain types of volcanic eruptions.

Three types of flows can be distinguished according to the type of eruption that produces them: flows related to domes or crumbling lava fronts; flows produced directly in summit craters; and flows discharged from fissures.

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There are igneous rocks whose formation due to the fragmetation of magma as a result of explosive eruptions.

Bomb :  This is a kind of pyroclast with size higher than 64 mm. They are totally or partially melted during their formation)

Block : This is a kind of pyroclast similar in size than bombs. (> 64 mm) During this formation they are totally solid.

Lapilli : (64-2 mm)

Ash : It is a kind of small pyroclast with size less than 2 mm.

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First stage.  At first, the oceanic crust was fractured and blocks were raised and the lavas were deposited during the submarine eruptions. These materials (plutonic rocks and marine sediments) has been seeing in La Gomera, La Palma and Fuerteventura.

-Second stage.  Submarine construction started in the last 20 million years, when the Islands emerged from the ocean.  Two cycles can be distinguished in the construction of each of the Islands:
1. The ancient series or first cycle gives rise to large volcanic buildings.  At present, these formations of considerable height are found mainly in the northern part of the Islands, where the erosive action of the sea and the rain has been more intense.

2. Nowadays the cycle is continuing in all the Islands, with the exception of La Gomera, and has formed very varied landforms. The lastest eruptions have taken part in the islands of Lanzarote, Tenerife, La Palma and El Hierro.  This fact indicates that the volcanism is still active in the Archipelago.

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The Canary Islands are part of a volcanic archipielago.

There are different theories about their origin:

- Hot spot theory (1971): It is based on the supposed existence of a fixed point in the mantle, characterized by an anomalous thermal regime (hot spot). In this point, the magma flows until the lithosphere creating a new island that  moves from the  west to east.

- Theory of the propagating fracture (1975).

- Theory of the raised blocks (1991). During of the Alpine period, the oceanic crust was fractured by a compression.  The result of that was a mesh of fractures and the lifting of failed blocks, which caused the generation of magmas.

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A volcano is made up of more parts than is commonly seen:

-CRATER:

It is the opening place that is located at the top of the volcano. During an eruption many materials are expelled such as lava, ash and all pyroclastic materials. Each crater varies in size and shape, but they are normally very wide and rounded. Volcanic explosions can be very intense, to the point of view of modifying the appearance of a crater by knocking down part of its structure.

-CRUST:

It is a part of the lithosphere, is divided into tectonic plates. Volcanic eruptions, earthquakes and other geological phenomena occur in the contact areas of these plates.

-VOLCANIC CONE:

It is the accumulation of solidified lava and pyroclasts outside the volcano, or the product of eruptions or explosions that have arisen over time. According to the volcano's history activity, the cone varies in thickness and size. This fact helps to define the crater.

The most common types of cones are slag, splash, and tuff.

- MANTLE:

The mantle is an inner layer of the Earth, that its situate between the core and the crust. It’s composed mainly by silicates.

-FIREPLACE:

It is the path that connects the crater with the magmatic chamber. Magma and gases that are to be released outwards during an eruption rise through there. A lot of rocks are torn away by the pressure are also incorporated and expelled.

-DOME:

A dome is a very viscous circular accumulation of lava that did not move far enough. Its solidification creates these natural domes that can reach different heights or extensions. The domes are located inside the volcano, but they do not usually exceed the limit of the crater. They are common in stratovolcanoes.

-COLADA:

La colada is a river of fluid lava that runs down on the slope of a volcano after an eruption. In his path, the colada destroy all the stuff.

-ERUPTIVE COLUMN:

The eruptive column forms a large column of gases and pyroclastic materials. Its height is between 5-40 km. These columns can also transport rock fragments that are a sign that the crater could be fracturing and that, in a short time, the violent expulsion of magma will start.

-VOLCANIC FISSURES:

Volcanic fissures are elongated channels where magma or internal gases are expelled to the surface. Normally the magma could be expelled by this fissures In various directions and covering huge land areas.

-MAGMATIC CHAMBER:

This part is found at great depths. In this place we can found deposits of the molten rock,  which comes from the Earth's mantle.

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A scientific study predicts that the Cumbre Vieja volcano will end up in the sea and cause a gigantic tsunami that will hit the East Coast of the United States.

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▪︎ Mercalli Intensity Scale

It is a qualitative assessment of the kind of damage caused by  earthquakes.

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▪︎ Richter Intensity Scale

It is a quantitative assessment of the kind of damage caused by  earthquakes.

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• Mount Fuji is a long active volcano.

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• Intermediate: They are less destructive

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• Deep: They are almost imperceptible due to the distance from the earth's surface.

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• Superficial: Generally these earthquakes are the most destructive.

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HAWAIIAN: fluid lavas, emit few ash and gases.

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PELEANO: very violent eruptions that form calderas. 

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PLINIAN: very violent eruptions rich in ash and pyroclasts. 

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VULCANIAN: loud explosions that pulverize lava to ash.

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VESUVIAN: violent explosions due to the expulsion of gases.

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2) Shield Volcan (Picture of Mauna Loa in Hawaii)

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3) Stratovolcano (El Teide, Canary Islands)

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Three factors:
-Danger
-Exposure
-Vulnerability

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-Lava flows
-Burning clouds
-Pyroclastic fall
-Toxic gases
-Lahars
-Tsunamis

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-frequency of the eruptions
-detect small tremors
-preparation of hazard maps

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-divert lava flows
-evacuation of the population
-construction hemispherical roofs
-fireproof shelters