Tectonics Flashcards
What are the three reasons why tectonic plates move:
Convection currents - Magma moves in circular motions within the earths mantle, magma rises for the core and as it cools it sinks back towards the core.
Slab pull - The denser plate sinks back into the mantle under the influence of gravity and it pulls the rest of the plate along behind.
Ridge push - Magma rises as the plates move apart and as the magma cools it becomes denser and slides down away from the ridge which causes the plates to move away from each other.
Is a continental or oceanic crust thicker?
Continental
Is a continental or oceanic crust denser?
Oceanic
Does a continental or oceanic crust sink?
Oceanic sinks when continental and oceanic meet
Is a continental or oceanic crust older?
Continental is older
Can a continental or oceanic crust be destroyed?
Oceanic is destroyed at destructive plate margins
Can a continental or oceanic crust?
Oceanic crust forms constantly at constructive plate margins
What is a seismic wave?
Waves caused by sudden releases of energy when friction builds up between two rocks
What is the epicentre?
The point on the earths surface directly above where the earthquake starts
What is the focus?
The point inside the crust where the pressure is released
What is a fault?
A fracture between two blocks of rock
What is an example of a continental constructive plate margin?
The East African rift valley
What is the associated hazard for a continental constructive plate margin and why?
Volcanic eruptions
The magma forces its way up through the weakened crust
What is the associated landforms for continental constructive plate margin?
Rift valleys
What is a named example for an oceanic constructive plate margin?
Mid Atlantic ridge
Wat are the associated landforms for an oceanic constructive plate margin?
Volcanic islands
New ocean crusts and ridges
What are the associated hazards with an oceanic constructive plate margin and why?
Earthquakes and volcanoes
Pressure builds up until seismic waves are released
What is a named example for a continental + continental crust?
Himalayas
What are the associated hazards for a continental + continental plate margin and why?
Earthquakes
Crust is neither created or destroyed
What are the associated hazards for a continental + continental crust?
Fold mountains
What is an example for a continental + oceanic crust?
Andes mountains (Nazca & S.America)
What are the four things you can do to reduce the risk of a tectonic hazard?
Monitoring
Predicting
Planning
Protecting
What are the associated hazard with a continental + oceanic crust and why?
Earthquakes and volcanoes
Plates move towards each other and friction builds up causing the oceanic plate to subduct and melt so magma rises up and creates volcanos.
What are the associated landforms for continental + oceanic crust?
Fold mountains
Composite volcanos
Ocean trench
How do volcanos from on a constructive plate boundary?
The plates pull apart and magma rises up from the mantle creating volcanic activity
How do volcanos form on destructive plate boundaries?
The oceanic plate sinks into the mantle and melts to form magma which rises up to erupt as a volcano - causes explosive volcanos.
What is an example of a conservative plate margin?
San Andreas fault
What is an associated hazard at a conservative plate margin and why?
Earthquakes
Plates stick and pressure builds up then a sudden release of energy releases seismic waves
How can you protect buildings against earthquakes?
Cross bracing buildings
Weighting roofs to counter act shaking
