Earthquakes Flashcards
How do earthquakes occur?
They are caused by the tension that builds up at all three types of plate margin. When the plates jerk past each other it sends out seismic waves which are the earthquake.
What is the focus?
The place in the lithosphere where the earthquake starts. The seismic waves spread out from here
What happens nearer the focus?
The waves are stronger and cause more damage
What is the epicentre?
the point on the Earth’s surface where the earthquake is felt first. It’s straight above the focus
What are other causes of earthquakes apart from movement at plate boundaries?
Reactivation of old fault lines that have not been active for a long time
Subsidence (when the ground sinks) as a result of deep mining
Pressure on surface rocks from water in large reservoirs
How do earthquakes cause damage?
Cause structure to collapse, tsunamis, avalanches, landslides or liquefaction
