Earthquake Weather - Background On Earthquakes

Background On Earthquakes

An earthquake is caused by a sudden slip on a fault. Tectonic plates are always slowly moving, but they can get stuck at their edges due to friction. When the stress on the edge of a tectonic plate overcomes the friction, there is an earthquake that releases energy in waves that travel through the earth's crust and cause the shaking that is felt. For example, in California, there are two plates - the Pacific Plate and the North American Plate. The Pacific Plate consists of most of the Pacific Ocean floor and the California Coast line. The North American Plate comprises most of the North American Continent and parts of the Atlantic and Arctic Ocean floor. The primary boundary between these two plates is the San Andreas Fault. The San Andreas Fault is more than 800 miles long and extends to depths of at least 10 miles. Many other smaller faults like the Hayward (Northern California) and the San Jacinto (Southern California) branch join the San Andreas Fault Zone. The Pacific Plate grinds northwestward past the North American Plate at a rate of about two inches per year.