Geography- Dynamic Planet - Restless Earth

Lithosphere

• Continetal Crust -Solid State, Composed of Granite, Temprature up to 900°c, 25km-80km thick
• Oceanic Crust -Solid State, Composed of Basalt, Temprature up to 900°c, 6km-8km thick

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Mantle

• Asthenosphere -Partially Molten State, Composed of Peridotites, Temprature from 1000°c- 1600°c
• Mantle- Solid State, Composed of Silica-based minerals, Temprature from 1600°c- 4000°c

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Core

• Outer Core- Liquid State: Very Dense, Composed of Iron/ Nickel, Temprature from 4000°c- 5000°c
• Inner Core- Solid State: Very Dense, Composed of Iron/Nickel, Temprature from 4000°c- 5000°c

• High tempratures caused by gradual radioactive decay creat rising limbs of material in the mantle called convection currents.
• These cool and rise before sinking again- like a lava lamp.
• Some of the material moves in sheets creating movements in the crust above it, which is pulled apart to form new crust or hotspots.

Contstructive Margins

• Formed by rising magma spliting the continental crust and forming new oceans
• EXAMPLE- The Eurasian Plate is seperating slowly from the North American Plate. This creates the mis-Atlantic ridge.
• Volcanoes and earthquakes can form

Destructive Margins

• The denser basaltic oceanic plate sinks beneath the continental plate.
• This is known as subduction and creates a deep ocean trench near the line of contact between the oceanic and continental plates
• As the oceanic plate subducts it builds pressure and temprature in the mantle
• This causes some lightweight material in the mantle to rise and form volcanoes
• The collision of plates also lifts and buckles the cotinental plate causing fold mountains 
• Earthquakes could also form.
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• Plates slide past each other or move in the same direction but at different speeds 
• This could mean that no crust is formed or destroyed and volcanoes do not form
• Great strain builds up along the junction with sudden lurches along the fault
• Earthquakes are frequent and often large
• EXAMPLE- San Andreas fault

The impact of any hazard, including earthquakes and volcanoes depends on:

• The size of the event
• Vunerability of the population- Poverty and high density of people
• Capacity of the population to cope- How prepared they are

Factors which determine the severity:

• Magnitude on richter scale
• The depth (Shallow=more destructive)
• The distance from epicentre
• The time of day
• Level of preparedness
• Quality of the emergency services

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Definitions 

Primary Impacts- Immeidate effect 

Secondary Impacts- The impact on properties and people after the earthquake has finished. Lack of supplies ect

Different types of volcanoes

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Composite

• Steep-sided, small area, alernate layers of ash and lava.
• Viscous/sticky lava- flows slowly
• Infrequent explosions and sometimes unpredicatble 
• Pressure builds up over time
• EXAMPLE- Mt Pinatubo

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Shield Volcanoes

• Gentle slopes, large area, almost all lava
• Fluid flows quick
• Basaltic magma
• Very frequent and generally gentle eruptions
• EXAMPLE- Mauna Loa (Hawaii USA)

Volcanic eruptions can be predicted if the right equiptment is in place

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• Gas emissions, earth tremors and 'bulging' of volcano's flanks can be meaured and used to predict eruptions
• Seisomemeter- Measures the movement in the earth (seismic waves)
• Tilt meters- Measure bulging of volcano
• Thermal imaging techniques to see heat around the volcano

Predicition Methods

• Seisometer- Used to pick up vibrations in the earth
• Laser Beams can be used to detect plate movement

Preperation Methods

• Emergency plans
• Well-trained and well funded emergency services
• Warning systems
• Evacuation routes
• Hazard resistant buildings
• Disaster kits
• Landuse planning