Guide Note:

One of the most deadly natural phenomena, earthquakes are caused by a sudden movement of the earth's crust from the release of stress accumulated along geologic faults or by volcanic activity.

Fast Facts:

1. The Richter Scale is a way of quantifying the seismic energy released during an earthquake
2. The largest recorded earthquake in history was in Chile on May 22, 1960
3. The Earth averages 500,000 measurable quakes per year

While an earthquake can be any seismic event that causes the ground to move, such as a nuclear explosion, mine collapse, or landslide, most naturally occurring earthquakes are the result of the release of energy caused by the friction between the planet's tectonic plates. Those locations on the Earth where these plates meet are typically the areas with the most frequent occurrence of quakes. For instance, the most seismically active area of the planet is known as the "Pacific Ring of Fire", a zone stretching around the perimeter of the Pacific Ocean. Areas such as the West Coast of the United States, and the Pacific coasts of Japan, Chile, and Central America experience quakes often, although the vast majority of these are too minor to be felt by humans. If a strong-enough earthquake strikes at sea, a tsunami, or tidal wave, can result. During an earthquake, the ground will move and shake, and even rupture, and if strong enough collapse buildings and bridges.