Earthquakes Flashcards
Why do earthquakes occur?
earthquakes occur when there is a sudden release of energy along a fault line due to tectonic plates moving. Tremors or seismic waves are radiated out from the focus.
where do earthquales occur?
Subdcution Zones
Transfrom plate boundaries
Divergent Plate Boundaries
how is a sudden release of energy created?
the plates appear to stick,so stress,tension and pressure build up and is released in energy and causes the plate to slip
where do the most dangerous earthquakes occur?
subduction zones as one plate is dragged back into the mantle
names an example of a subduction zone where earthquakes occur
Off the coast of japan which is known to be the most deadly in the world. The pacific plate is brought beneath the eurasian plate.
name an example of a transfrom boundary where earthquakes occur
The san adreas fault line in California. Here the american and pacific plates slide past each otherin the same direction.
name an example of a divergent boundary where earthquakes occur
The mid-Atlantic Ridge but are not as frequent or dangerous.
what is a shallow focus earthquake?
These occur when the focus is close to the surface(less than 80km deep).
These are more common and cause most damage
what is a deep focus earthquake?
these occur when the fous is btween 300-700km deep in the surfaceand rarely cause damage because most energy is lost by the time the waves reach the surface.
what are P-waves?
Primary Waves, these are the fastest waves and first to be recorded. These waves travel through molten material
What are S-waves?
Secondary Waves, These are slower-moving waves that travel through rock.
What are surface waves?
these are the slowest of all 3 and travel along the surface.
what are seismic gaps?
these are time gaps between earthquakes, the longer the gap, the more imminent the next earthquake.
what are 4 prediction methods for earthquakes?
Animal Behavior
Lasers which monitor ground movement
changes in level of water
radon gas levels
