The San Francisco earthquake of 1906 involved a 6 meter horizontal displacement of bedrock. Sometime after the main shock wave, aftershocks can occur because of the continued release of frictional stress. Most aftershocks are smaller than the main earthquake, but they can still cause considerable damage to already weakened natural and human constructed features. Distribution of earthquake epicenters from 1975 to 1995. Depth of the earthquake focus is indicated by color.
Deep earthquakes occur in areas where oceanic crust is being actively subducted.
Earthquake Waves Earthquakes are a form of wave energy that is transferred through bedrock. The point on the Earth's surface directly above the focus is termed the epicenter . Movement of body waves away from the focus of the earthquake. The epicenter is the location on the surface directly above the earthquake's focus. Body waves are seismic waves that travel through the lithosphere.