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.
A fault is a fracture in the Earth's crust where one side has moved in relation to the other. A fault can be very short, or it can be hundreds of miles in length. The plates of the Earth are in constant, but very slow, motion. California lies on the Pacific plate, which is part of the North American plate; the boundary between these two plates is the San Andreas Fault, which is a fracture that runs from Imperial County to Humboldt County.
When two sides of a fault such as the San Andreas fault slip suddenly against one another, an earthquake results. The Pacific and North American plates move about 1.5 inches past one another annually, and the friction caused by this passage causes stress that is released by slippage along the fault plane. This results in the shaking feeling of the earthquake.
Although California is known for its many earthquakes, Alaska has more earthquakes per year.Learn More
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 >
The United States Geological Survey estimates that there are around 50 earthquakes per day in the world that can be located. This amounts to around 20,000 earthquakes annually.Full Answer >
Earthquakes are formed by a sudden, violent underground movement of the Earth's crust. These natural phenomena typically occur along a fault line or fault plane, which is a geological region of compressed rocks dividing crustal plates.Full Answer >
Earthquakes are the result of two of the Earth's crustal plates slipping past each other, otherwise known as plate tectonics. The vibrations caused by this sudden movement reverberate through the surrounding rock structures, and they are felt as tremors. Earthquakes are most common among the geologically active regions at the borders between plates of the Earth's crust, also known as fault zones.Full Answer >