Coachella Valley’s quake future is dire, scientist says

RANCHO MIRAGE, Calif. -- Sandwiched between the powerful San Andreas and San Jacinto faults, the Coachella Valley could be the epicenter of the most devastating earthquake in the country, one that is already 300 years overdue, a government scientist warned Thursday.

“There will be several thousand dead and billions of dollars in damage,” said Lucy Jones, a seismologist at the U.S. Geological Survey and a member of the California Seismic Safety Commission. She also said a devastating quake could topple buildings as far away as Los Angeles.

This apocalyptic vision was presented to members of the seismic safety panel who met in Rancho Mirage to discuss how the Coachella Valley would handle a catastrophic earthquake. The meeting took place the day a quake registering magnitude 4.6 shook up Chatsworth.

The power of that quake was negligible compared with the scenarios laid out by Jones.

Historically, major temblors have struck the Coachella Valley every 150 years, on average, but for reasons no one can explain, it’s been quiet for 300 years.

“Whatever it is that makes for a long interval is happening now, and we know that long interval can’t last forever,” Jones said. “This is an overdue fault.”

Stresses are building under the San Andreas and San Jacinto faults, which could cause the ground to move as fast as 10 feet a second during an earthquake. The Northridge quake in 1994 moved about 6 feet a second.

A likely scenario would have a magnitude-7.8 earthquake strike in the Salton Sea, extending north and west toward Palmdale. Jones predicted the shaking could last more than 100 seconds, kill thousands, destroy homes, collapse the I-10 and I-15 freeways, ignite petroleum pipelines and leave untold thousands homeless in potentially searing desert heat. The long-term effects, she said, could be akin to the economic collapse of New Orleans and the Gulf region following Hurricane Katrina.

“This will have long-term economic implications across the nation,” she said.

It would be even worse should the quake hit during Santa Ana winds, possibly adding fires as another major element to the disaster, Jones said.

Jones said Los Angeles would not be spared. The tremendous forces released by the slipping faults would send shock waves through the earth that could easily collapse tall buildings in Los Angeles the way the 1989 Loma Prieta earthquake, which hit near Watsonville, collapsed the Bay Bridge between Oakland and San Francisco about 50 miles away.

“This is a whole new level of disaster,” she said.

Riverside County emergency officials said that unlike tornadoes and hurricanes, which occur every year, earthquakes hit sporadically, and it’s hard to get people to prepare for them.

“In times of disaster we have everyone’s ear, but when it comes to preparedness we can’t get anyone’s attention,” said John Hardcastle, emergency services coordinator for Palm Springs.

Kathleen Henderson spends two or three days a week traveling throughout the county urging residents to be ready.

“My biggest concern is the heat and air conditioning for the children and the elderly,” said Henderson, emergency services coordinator for the Riverside County Fire Department. “If the quake happened during the hottest period of the year, I think we would have a lot of heat-related emergencies and deaths. We have a lot of elderly people. They will need to talk to a doctor about how much medication they should have on hand.”

Jones, chief scientist for the USGS’ multi-hazards demonstration project, is putting together a detailed report describing the likely effects of a major Coachella Valley earthquake.

“If something happens, no one can say you haven’t tried to warn us,” Rancho Mirage Mayor G. Dana Hobart told Jones. “We should put a box on the front page of the paper each day saying we are 3,600 months and 75 days overdue for a quake to remind people to be ready.”

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david.kelly@latimes.com