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Tectonics (Volcanoes (Types - Shield, Strato, Active, Dormant, Extinct…
Tectonics
Volcanoes
Created by a constructive plate boundary when they pull apart, releasing magma from beneath the crust which solidifies creating a volatile
In addition to lava, volcanoes have...
Lahar - a destructive volcanic land slide or mudflow, consisting of a mixture of volcanic, debris of mud, rock and water
Pyroclastic flows - Flow down the sides of the volcano at fast speeds and up to 400 degrees Celcius. Pyroclastic flows are a mix of hot steam, ash, rock and dust.
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Types - Shield, Strato, Active, Dormant, Extinct
Shield - Low, Gently sloping sides. They are formed quite thin, runny lava, fairly frequent and gentle eruptions
Strato (or composite) - Have alternating layers of ash and lava. Eruptions can be violent and result in pyroclastic flows mixing hot steam, ash, rock and dust.
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Earthquake
When there is a destructive plate boundary the oceanic plate will go beneath the continental because the oceanic plate is denser, this builds pressure which releases seismic waves which result in an earthquakes
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Seismograph - records how much the earth shakes and plots this on a graph.
The strength of an earthquake (magnitude) is measured using the Richter Scale.
1=low
10=high
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CAUSES: The earthquake happened along a conservative plate margin marking the bounder between the North American plate and the Caribbean plate. At 16:53 on January 12th 2010 the island of Haiti was struck by a powerful 7.0 magnitude earthquake. The earthquake was caused by stress building up along the conservative plate margin, when this stress was released there was a sudden slip along the fault. The earthquake was followed by several large aftershocks of up to 5.0 on the Richter scale.
EFFECTS:The earthquake devastated large parts of the capital Port-au-Prince and resulted in massive loss of life making it one of the most destructive earthquakes of all time.
PRIMARY EFFECTS: 230,000 people were killed. 180,000 homes destroyed by the ground shaking.
Destructive - Oceanic crust, Continental Crust, Density, Subduction zone, Pressure
Density - The oceanic plate is denser than the continental crust therefore causing the oceanic plate to go down.
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Friction and increase in temperature cause the crust to melt and some of the newly formed magma may be forced to the surface to form volcanoes.
Case Studies
Monserrat Volcano
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11,000 evacuees fled to north of the island and to the UK
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Aftermath - Seismic monitoring, Deformation monitoring, environmental monitoring, volcanological monitoring. The population is now half, entry into the south is not allowed. More tourism.
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Japan Tsunami
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28,000 houses destroyed on the North East coast
The major long-lasting effect was that it damaged the Fukushima nuclear programme. The damage leads to meltdowns and radioactive leaks. Tens of thousands were evacuated.
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Conservative - Where two plates slide past each other, no new landscape is formed therefore no new volcanic activities. Pressure is built up until released and when the pressure is released, the earth jerks violently.
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Constructive - two plates moving apart, creates oceanic crust (result of rising magma to fill the gap made) - this process is called sea floor spreading