1. A violent shaking of the earth's crust that may cause destruction to buildings and results from the sudden release of tectonic stress along a fault line or from volcanic activity.
2. Any event that causes an upheaval in society, politics, or someone's life.

Predicting Earthquakes

Almost all earthquakes are insignificant. A small segment of a fault, far underground, jerks a little, but the rumble is imperceptible at the surface and not even noticed.

With a few quakes, the fault continues to break and the ground jumps significantly resulting in the earth shaking in cataclysms.

A gap in geological knowledge apparently makes earthquake predictions a frustrating and unreliable effort to calculate the true risk that human constructions like a water reservoir or a geothermal power plant could inadvertently set off a deadly quake.

Scientists know that some human activities from oil extraction to power plants can trigger an earthquake.

Geologists do not know how the pieces of the earth's crust that usually squeeze together tightly with high friction slip past each other smoothly during a large earthquake, as if sandpaper suddenly changed into Teflon."

A general presentation of earthquake history unit.