Earth and Space Science / Unit 4: Earthquakes and Volcanoes
4.2 What Causes Earthquakes
Notes
An earthquake is shaking caused by sudden release of energy in rock.
- Elastic rebound: rock slowly bends and stores energy as stress builds, then the fault slips and the rock snaps back.
- The focus is where the rupture starts underground. The epicenter is the point on the surface directly above it.
- Most earthquakes happen at plate boundaries, especially the "Ring of Fire" around the Pacific.
- Smaller aftershocks follow a large quake as the crust adjusts.
Practice
The epicenter of an earthquake is:
The focus is underground; the epicenter is directly above it.
Elastic rebound describes:
Energy builds slowly and releases suddenly.
Why do most earthquakes occur around the edges of the Pacific Ocean?
The Ring of Fire is a belt of plate boundaries.
Ready for more? Take the Unit 4 test.