volcanic eruptions
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Volcanic Eruptions
GLOSSARYBomb – a lump of rock thrown out in an eruptionCrater – a deep hollow at the top of a volcanoCrust – The top layer of the EarthEruption – the release of gases, magma and rock from a
volcanoLava – melted rock that flows down the volcanoMagma – melted rock inside the EarthMolten – melted, liquidVent – a crack on the side of a volcano where magma can
escape
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What is a volcano?
• A volcano is a vent or 'chimney' that connects molten rock (magma) from within the Earth’s crust to the Earth's surface.
• The volcano includes the surrounding cone of erupted material.
vent
cone
magma chamber
conduit
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How and why do volcanoes erupt?
• Hot, molten rock (magma) is buoyant (has a lower density than the surrounding rocks) and will rise up through the crust to erupt on the surface.– Same principle as hot air rising, e.g. how a hot air balloon works
• When magma reaches the surface it depends on how easily it flows (viscosity) and the amount of gas (H2O, CO2, S) it has in it as to how it erupts.
• Large amounts of gas and a high viscosity (sticky) magma will form an explosive eruption!– Think about shaking a carbonated drink and then releasing the
cap.• Small amounts of gas and (or) low viscosity (runny) magma will
form an effusive eruption– Where the magma just trickles out of the volcano (lava flow).
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• Three products from an explosive eruption– Ash fall– Pyroclastic flow– Pyroclastic surge
Explosive Eruptions
Pyroclastic flows on Montserrat, buried the capital city.
Parts of Volcanoes
Main Vent
Side Vent
Crater
Lava
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(DEAD)
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ACTIVE VOLCANOES-which are likely to erupt at any moment.DORMANT VOLCANOES-which lie dormant for centuries, but then erupt violently and silently.EXTINCT VOLCANOES -no longer likely to erupt.
SUM UP :-
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Types of Volcanoes
Types of Volcanoes
Shield Volcano
Kilauea,Hawaii
CompositeVolcano
Mt. St. Helens, Washington
Cinder ConeVolcano
Parícutin, Mexico
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Shield volcanoes can span across hundreds of miles and they can be huge vertically that they can reach the clouds of earth very easy. Shield volcanoes have a slow slope and consist of frozen lava after it is hardened. Shield volcanoes almost always have large craters at their summit.
SHIELD VOLCANORATIKADELHI INDIA
Mt. Kilauea
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Cinder cone volcanoes consist of mostly loose, grainy cinders and have very little to no lava. Cinder cone volcanoes are normally small about a miles span and about one thousand feet vertically. Cinder cone volcanoes have fairly steep slopes and normally have a small crater at the top.
CINDER CONE VOLCANO
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Mt. Parícutin
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Composite volcanoes have another name called “Strato Volcanoes.” Composite volcanoes consist of lava that is mixed with sand or gravel which in turn creates cinders or volcanic ash.
COMPOSITE VOLCANO
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Mount St. Helen
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Volcanoes around the world
Volcanoes per Continent
050
100150200250
Austra
lia
South
Am
erica
North
Am
erica
Asia
Europ
e
Africa
Antar
ctica
Australia
South America
North America
Asia
Europe
Africa
Antarctica
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Volcanoes Around the world
Antarctica2%
Africa13%
South America
11%
North America
27%
Europe4%
Australia6%
Asia37%
GRAPHICAL PRESENTATION
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World Map of Volcanoes
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Multiple Eruption volcanoes
Kilauea- Hawaii
Vesuvius-Italy
Mt. St. Helen- Washington
March 2005March 18,
1944September 23,
2004
November 2000 79 AD May 18, 1980
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