Common Earthquake Terms

Epicenter
The point on the Earth's surface above the point at depth in the Earth's crust where an earthquake begins.

Fault
A fracture or crack along which two blocks of rock slide past one another. This movement may occur rapidly, in the form of an earthquake, or slowly, in the form of creep.

Seismologists
Scientists who study earthquakes
and their causes and results.

Seismogram
The record made by a seismograph.

Seismographs
Instruments that make an automatic record of the time, duration, direction, and intensity of earthquakes.

Theory of Plate Tectonics
States that the earth’s crust is divided into a number of relatively rigid plates that collide with, separate
from, and translate past one another at their boundaries, this disruption commonly results in earthquakes.

Modified Mercalli Intensity (MMI) Scale -
The Modified Mercalli Intensity Scale is commonly used in the United States by seismologists seeking
information on the severity of earthquake effects.