Southern California Earthquake Advisory Issued- Risk of Major San Andreas Quake

Southern California Earthquake Advisory Issued- Risk of Major San Andreas Quake

Photo courtesy of OES

The California Office of Emergency Services (OES) issued an earthquake advisory warning residents and officials in Ventura, San Diego, San Bernardino, Riverside, Orange, Los Angeles, Kern and Imperial counties that there was a greater possibility of a major earthquake through Oct. 4.

The USGS says that data indicates a one percent chance of a magnitude 7 or greater earthquake on the Southern San Andreas fault within the next seven days- about 600 times higher than the normal risk level. 

Officials are preaching caution and calm, but are encouraging people to take the opportunity to prepare a quake plan and get emergency supplies gathered. FEMA and most other agencies recommend at least 2-3 days of food and water, communication and light tools, shelter and warmth, and other preparedness tools. 

“California is earthquake country. We must always be prepared and not let our guard down,” says OES Director Mark Ghilarducci. “The threat of an earthquake on the San Andreas fault hasn’t gone away, so this is another important opportunity for us to revisit our emergency plans and learn what steps you need to take if a significant earthquake hits.”

More than 200 earthquakes have been recorded in the past few days. This marks only the third time since earthquake sensors were installed in 1932 that this part of the state has seen such a swarm.

Scientists estimate that a big earthquake happens in this area once every 150 or 200 years, so experts think the region is long overdue for a major quake. The San Andreas fault’s southern stretch has not ruptured since about 1680 — more than 330 years ago.

“Any time there is significant seismic activity in the vicinity of the San Andreas fault, we seismologists get nervous,” said Thomas H. Jordan, director of the Southern California Earthquake Center, “because we recognize that the probability of having a large earthquake goes up.”

In 2008, USGS researchers simulated a magnitude 7.8 earthquake in the Salton Sea part of the San Andreas fault. The USGS simulation predicts that when the fault hits Cajon Pass, Interstate 15 and rail lines could be severed. Inland Empire towns could become a cascade of fallen brick, crushing people under  collapsed buildings that had never been retrofitted.

Los Angeles would feel shaking for a full minute (compared to only 7 seconds during the 1994 Northridge earthquake). The quake could reach as far as Oxnard, Bakersfield and Santa Barbara. About 1,600 fires could likely spread across Southern California due to broken gas and electric lines, and powerful aftershocks of up to 7 magnitude could affect as far away as San Diego county.

The ShakeOut simulation puts the death toll at 1,800 people, and such an earthquake could cause 50,000 injuries and $200 billion in damage.

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  • Zach Miller