Quakes Along Southern San Andreas Prompt Study, Concern
While there have been no reports of damage or injuries associated with the 4.8 magnitude quake that occurred near Bombay Beach early this morning, the U.S. Geological Survey has been tracking an unusual sequence of small earthquakes (50+) that have been clustered in the area. The majority of these quakes, just south of Bombay Beach, have been less than 2.5 in magnitude.
As a precaution, the California Earthquake Prediction Evaluation Council (CEPEC) met by teleconference this morning to discuss the recent seismic activity.
Based on scientific data, and the fact that these most recent earthquakes have been in close proximity to the San Andreas Fault, there is increased concern that these earthquakes could trigger a large earthquake (magnitude 7.0 or stronger) on the San Andreas itself. Historically, a major earthquake on this southern portion of the San Andreas Fault has not occurred in over 300 years, so the probability of a large earthquake is thought by seismologists to be higher than on portions of the fault that have ruptured more recently (e.g. in 1857 and 1906).
CEPEC believes that there is a 1 percent to 5 percent chance of a large earthquake (magnitude 7.0 or greater) on the San Andreas Fault over the next few days. However as each day passes, the risk of a large San Andreas earthquake decreases. This assessment is based on methodology developed for assessing foreshocks on the San Andreas Fault.
The California Emergency Management Agency (Cal EMA) will continue to monitor the situation and keep in contact with CEPEC scientists over the next few days. Cal EMA recommends that operational areas reach out to agencies and jurisdictions within their operational area to raise their awareness of today’s events. It is a good time to ensure the readiness of systems essential to emergency operations and remind the public about the importance of being prepared for earthquakes.