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11 Cards in this Set
- Front
- Back
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Primary effect: hazards which are a direct result of the volcanic eruption |
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Primary effect Lava Flows |
- Layers of molten lava can destroy almost everything on their path - trees and buildings are burnt and transport links are severed. Can threaten whole settlements |
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Primary effect Pyroclastic Flows |
- Fast moving avalanche of volcanic material (cinders, ash, pail (small stones), pumice and volcanic bombs) and hot gases - referred to as a 'Nuée ardente'/glowing cloud |
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Primary effect Tephra |
- Solid material of varying grain size, from volcanic bombs to ash, ejected into the atmosphere. |
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Primary effect Volcanic gases |
Variety of dangerous gases emitted: - Hydrogen sulphide (most noticeable) - CO2 (killed 1700 people in Cameroon, 1986) - CO [Carbon Monoxide] |
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Secondary Effect: Hazards which are a consequences of the primary effect |
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Landslides |
- Collapse of volcano flank as eruption takes place - e.g. eruption of Mount St. Helens, 1980 - largest landslide ever witnessed |
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Tsunami |
- oversized waves in the sea/ large lakes triggered by the collapse of volcano flanks or caldera forming volcanic events - e.g. Santorini caldera - wiped out 80% go people at a time of great civilisation |
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Lahars |
- Volcanic mud flows caused by the ash erupting from a volcano mixing with river water - worst cases are when there is high rainfall/snowmelt as eruption occurs - can occur days, weeks or years after eruption - ash layers are 'reworked' by heavy rain |
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Flooding |
Melting glaciers/ ice caps can release huge quantities of water in very short periods - Mount St. Helens, 1980 + Grimsvotn, Iceland, 1996 |
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Climate Change |
The large volumes of ash and gas ejected into the atmosphere can reduce global temperatures by blocking out sunlight. 1783 Laki eruption had a global impact which led to reduced crop yield 1991 Mt. Pinatubo - 0.5 degrees fall in mean global temperatures |
