The California Office of Emergency Services has issued an earthquake advisory for Southern California, alerting several counties that the probability of a major earthquake is more likely over the next few days; the advisory runs through Tuesday. The Earthquake Advisory is in effect for these counties:
- Ventura
- San Diego
- San Bernardino
- Riverside
- Orange
- Los Angeles
- Kern
- Imperial
The advisory was issued following a series of small magnitude earthquakes near Bombay Beach, Salton Sea. The swarm occurred in a region known as the Brawley seismic zone, which is located near a fault network that connects the southernmost end of the San Andreas fault with the Imperial fault. Last Monday alone, 20 earthquakes with a magnitude of 2.5 or greater occurred in the area. The quakes reached a magnitude of 4.3 twice and 4.1 once, according to the USGS. About 200 earthquakes were measured in this latest swarm.
Forecasting earthquakes and the science of seismology is in its infancy compared to the sophistication and accuracy seen in weather forecasts and the science of meteorology. Advisories like these are relatively new and accuracy remains low. The California Earthquake Prediction Evaluation Council, which issues these earthquake advisories, believes that stresses associated with this recent swarm may increase the probability of a major earthquake on the San Andreas. However, the odds of that major earthquake remain extremely low: only 1% increase in risk through October 4.
Residents don’t need to do anything other than have a heightened awareness of earthquake safety and know what to do should a big earthquake occur.
While the short-term risk is low, the risk of a large earthquake in the coming years is almost at a definite 100%. New calculations reveal there is a 99.7% chance a magnitude 6.7 quake or larger will strike in the next 30 years. The odds of such an event are higher in Southern California than Northern California, 97% versus 93%.
California is one of the most seismically active regions in the world. More than 300 faults crisscross the state, which sits atop two of Earth’s major tectonic plates, the Pacific and North American plates. About 10,000 quakes each year rattle Southern California alone, although most of them are too small to be felt.
