Earthquakes and Plate Tectonics

An earthquake is caused by a sudden slip on a fa
"Foreshock" and "aftershock" are relative terms. Foreshocks are earthquakes that precede larger earthquakes in the same location.
The moon, sun, and other planets have an influence on the earth in the form of perturbations (small changes) to the gravitational field.
Surface rupture occurs when movement on a fault deep within the earth breaks through to the surface. NOT ALL earthquakes result in surface rupture.
The Geysers Geothermal Field is located in a tectonically active region of Northern California.
Earthquakes do occur occasionally in Antarctica, but not very often. There have been some big earthquakes--including one magnitude 8--in the Balleny Islands.
Learn more:Earthquakes for KidsTopics for Earthquake Education 
Earthquakes induced by human activity have been documented at many locations in the United States and in many other countries around the world.