California has a relatively high number of earthquakes due to its position on both the Pacific and North American Plates. These plates are in constant motion, and earthquakes occur when their sides slip against one another suddenly.Know More
The San Andreas Fault is the boundary line between the two plates, and it runs roughly from north to south along much of the length of the state. There are hundreds of other smaller faults in the state, with about 200 of them considered potentially dangerous due to their slip rates. An estimated 70 percent of the state's population lives within 30 miles of a fault, where noticeable levels of ground shaking can occur.
California generally experiences two or three, large-scale, earthquakes per year of a magnitude of 5.5 or greater, the level at which moderate damage to structures can occur. Small earthquakes occur on an almost daily basis throughout the state, but most are too small to be felt. The state experienced over 2,900 earthquakes in total in 2014.
Though California is one of the regions of the world most prone to earthquakes, it does not have the most or the largest quakes. Within the United States, Alaska has both more and larger earthquakes.Learn more in Earthquakes
Earthquakes are usually triggered when rock located beneath the ground, on top of fault lines, breaks and suddenly releases a significant amount of energy. The immediate and rapid release of energy caused by earthquakes generates seismic waves, which cause shaking motions that start below the Earth’s surface and spread across large distances.Full Answer >
Earthquakes happen daily across the United States, though they vary in magnitude. For instance, the United States had 3,836 earthquakes in 2012, but only five of them were above six on the Richter scale, and none of them exceeded seven.Full Answer >
A large number of earthquakes occur in California because it is home to hundreds of known faults. At least 200 of the faults in California are considered potentially hazardous, and more than 70 percent of the population of the state lives within 30 miles of a fault.Full Answer >
According to the United States Geological Survey, several million earthquakes occur worldwide each year. It is difficult to refine this estimation to an exact number because many earthquakes go undetected, either because they occur in locations that are uninhabited or barely inhabited, or they are too small in magnitude to be detected by seismographs or other forms of detection.Full Answer >