Earthquakes are common across California, with the center of activity occurring along the San Andreas Fault. The fault runs along the western coast of California, near the cities of Los Angeles, San Francisco, and San Diego.
There are other large faults that run through California. The Gartlock Fault is oriented east to west north of Los Angeles and split north into the Owens Valley Fault. Earthquake activity took place along the Gartlock fault in the 1950s and the Owens Valley Fault in 1857. There many smaller earthquake zones, especially in Southern California, which have been more active in recent years. There is the Sierra Madre fault, San Jacinto, and the San Gabriel. All of these faults have been at the focus of powerful earthquakes within the last 50 years.
Another active earthquake area is at Mono-Inyo Lakes, and the Long Valley Caldera. These earthquake zones are caused by volcanic activity. Many smaller tremors are measured around these volcanic areas, but isolated large quakes are known to occur.
A large earthquake struck near Mexicali on Easter Sunday registering 7.2 on the Richter scale. According to the USGS, aftershocks from this large quake have continued to rattle the region. These aftershocks have all been in the 5.0 to 5.5 range, which is enough to cause slight damage and will be felt by people near the epicenter. The main area affected by these aftershocks are near Calexico, which is a California border city along the Mexico-US line.
When and Where Will the Big One Hit?
The question everyone asks is where and when the next big tremor will occur across California. The famed 1906 earthquake leveled San Francisco, and Central California may be due for another big quake. Much of the recent activity has centered around southern California, where some aftershocks are still ongoing near the US-Mexico border. Another area of earthquake activity has been occurring just of the Northern Coast of California with earthquake magnitudes ranging from 4.0 to 6.5 on the Richter Scale.
Earthquake predictions, are difficult to make, due to the lack of data available along fault lines. Scientists can study surface movements along faults, and gain some understanding of stress and pressures that tectonic plates are exerting upon one another at the surface, but gaining an understanding of what is happening underground is difficult.
The Uniform California Earthquake Rupture Forecast was created by a group of engineers and scientists. They release regular forecasts on earthquake probabilities for different parts of the state. Their current earthquake prediction calls for a 99% chance of a 6.7 or greater magnitude earthquake within the next 30 years. Going by past history of earthquakes in an around California, this forecast will probably be true.
Short term earthquake predictions are nearly impossible to make, since there is little data available. Scientist can try to model the dynamics of how tectonic plates move against one another, but without sufficient data, short term predictions, of a few days or weeks are difficult to make. Scientists must also consider the economic impact of making earthquake predictions for a large population base that turns out to be a false alarm. So for now, Californians will just have settle for the risks involved in living in an earthquake zone.