GEOGRAPHY AQA: TECTONICS

paper 1 tectonics

Constructive plate boundary

Where tectonic plates move away from each other

Destructive plate boundary

Where an oceanic plate subducts under a continental plate.

Conservative plate boundary

Where two tectonic plates slide past each other

What are the two types of crust?

Oceanic and continental

Mantle

Earth's thickest layer, contains magma, layer in which tectonic plates slide across.

Outer core

Layer of molten iron and nickel.

Inner core

Extremely dense magnetic layer made of iron and nickel.

How thick is oceanic crust?

7km

How thick is continental crust?

35km

Which crust type is denser?

Continental

Which crust type is younger?

Oceanic

Hot spot

Place where magma rises through volcanic crust

Examples of hot spots

Hawaii, Iceland and Yellowstone

Geothermal energy

Thermal energy from the earth's crust.

Convection current

Heat-driven cycles that occur in the air, ocean and mantle.

How do convection currents affect tectonic movement?

When convection currents rise to the surface, tectonic plates move away from each other.

How do collision boundaries form land?

Neither continental plate is subducted due to having similar density, creating fold mountains.

How do constructive boundaries form land?

Magma wells up to fill gaps, forming new crust. This causes earthquakes and shield volcanoes to form.

How do subduction boundaries form land?

The plates are moving towards each other. The heavier oceanic plate subducts down, grinding against the lighter continental plate.

How do conservative boundaries form land?

Two plates are moving in the same direction at slightly different angles and speeds.

Richter Scale

A quantative scale of 1-10 measuring the strength of an earthquake.

Mercalli scale

A quantative scale of 1-12 measuring the damage caused by earthquakes based on observation.

Seismometer

An instrument which measures the magnitude of an earthquake.

Iceland

An island in the North Atlantic Ocean and in the northern hemisphere.

Which direction is Iceland from the UK?

North-west

Which plates does Iceland sit on?

Eurasian and North American.

Epicentre

The point directly above the focus on Earth's surface.

Seismometer

An instrument used to measure the magnitude of an earthquake.

Aftershock

Smaller earthquakes following the events of a main one.

Fault

A break or fracture within a layer of rock.

Focus

The point at which the rock moves. Where seismic waves occur.

Seismic waves

Waves produced by sudden movement of materials within the Earth.

Focal depth of Nepal

8km

Focal depth of Christchurch

5km

Primary impacts of Nepal

9000 dead, 19000 injured, 7000 schools destroyed.

Primary impacts of Christchurch

185 dead, 3129 injured, 10000 buildings destroyed.

Secondary impacts of Nepal

Avalanches and landslides, evacuation, 300k homeless, $5 billion cost

Secondary impacts of Christchurch

Liquefaction, 1/5 migrated, $40 billion cost

Immediate responses for Nepal

Shelter and support seeked, 500k tents provided for homeless, 300k migrated

Immediate responses for Christchurch

State of national emergency. 300 Australian officers provided aid

Long term responses for Nepal

Landslides cleared, 7000 schools rebuilt.

Long term responses for Christchurch

Temporary housing, 80% of roads cleared.