Tectonic hazards Flashcards
What did Wegner theorise and why.
Continental drift because he said the continents appear to fit together like a jigsaw.
What are the 2 main causes for why plates move?
Convection currents-The mantle rises to the crust due to the core being hot, then it cools down, sinks and repeats the process. This then pushes the plates on the earths surface
Slab pull-As the oceanic crust is going down into the mantle because of the weight of it, it is bringing the rest of the plate with it.
What is the global distribution of tectonic hazards?
They occur in lines on plate margins, or they occur in hotspots, where the crust is particularly thin.
What is a constructive plate margin?
Two crusts moving away from each other, the magma escapes as lava through the gap, then it cools down and forms new crust. e.g. Mid-Atlantic ridge. These bursts of magma happen lots, building up the shield volcano. Little earthquake activity.
What is a destructive plate margin?
An oceanic and continental crust moving together, oceanic being denser and heavier, subducting below. It then melts, making more magma in the subduction zone. It then rises and goes through the crust as a composite cone volcano, made up of ash and lava volcanoes. Earthquakes also occur at the focus point in the subduction zone due to stick and slip. e.g. Nazca and South American plate.
What is a conservative plate margin?
Plates moving together in the same or opposite directions, this causes earthquakes because of stick and slip. This line is called the fault line. e.g. the San Andreas fault
Why do people live near tectonic hazards?
Fertile soils, Geothermal energy, Tourism and Mining
Fertile soils:
Volcanoes spew out ash and then goes into the soil, rich in minerals e.g. citrus fruits
Geothermal energy:
Iceland make 90% of electricity, renewable, using the heat from the earth to make steam to turn a turbine
Tourism:
People want to see the geothermal activity, jobs, money to be made e.g. Yellowstone park
Mining:
Rich in sulphur and gold
What are the 4 p’s
Prediction, Planning, Protection and Preperation
Prediction for earthquakes:
Radon gas emissions, foreshocks, animal behaviour
Planning for earthquakes:
Earthquake preparation days, drills in schools
Protection for earthquakes:
Reinforcing building such as bird cages(steel frames), deep foundations with shock absorbers, swaying buildings, shutters on windows, counterweight and an evacuation area.
