What an earthquake is
An earthquake is the shaking of the ground when rock breaks and moves at a fault.
Fault: a break in rock where the rock moves. Focus: the point under the surface where the rock breaks first.
Watch a fault slip
Seismic waves: waves of energy that travel through Earth. Epicenter: the point on the surface directly above the focus.
CAUTION: Do not run outside while the ground shakes. Drop to the ground, take cover under a table, and hold on.
Try it
Build stress until the fault slips
- Pick a fault.
- Move the slider slowly to the right to add stress.
- Look at the rock layers and the seismograph.
The bar shows how close the fault is to a slip.
Quick check
Answer 5 questions. You see your score at the end.