REGION: San Andreas due for a big quake

Damage, carnage would dwarf Northridge temblor

By DAVE DOWNEY - Staff Writer | Friday, July 25, 2008 6:25 PM PDT ∞

Massive earthquakes rock the southern San Andreas fault about once every 150 years.

"And it's been 151 since the last one," said Lucy Jones, chief scientist at the U.S. Geological Survey in Pasadena and one of Southern California's foremost quake experts.

"That doesn't mean it has to happen tomorrow," Jones said, saying the return time for The Big One can vary from 45 to 350 years. "But at some point, we're going to run out of luck."

That last one was a magnitude-7.9 monster that roared down the fault like a freight train from Paso Robles to the Cajon Pass near San Bernardino in 1857.

Jones this week outlined for a crowd of 300 people at Fallbrook High School a similar scenario that scientists say could be the signature of the next one: Erupting near the southern end of the mighty San Andreas at the Salton Sea, a magnitude-7.8 shaker rolls north for 200 miles along the fracture in the Earth before stopping at a point north of Los Angeles.

If that scenario should one day come to pass, no one should take comfort in the epicenter being the Salton Sea, far from the region's heavily populated areas, Jones said. On the contrary, at every point along the 200-mile path, massive shaking would occur.

"An earthquake begins at the epicenter ... but then it ruptures all the way down the fault," she said.

The Los Angeles area would suffer severe and extensive damage, but North San Diego County and Southwest Riverside County probably would escape shaking because the fault is well to the north and east.

Fire biggest foe

The San Andreas fault runs 800 miles through California. It slices under San Francisco and runs southeast from there. In Southern California, it runs east-west along the base of the San Gabriel and San Bernardino mountains, before veering southeast through the desert toward the Salton Sea and the Imperial Valley.

The Big One's 200-mile journey would dwarf the 10 miles that the magnitude-6.7 Northridge quake traveled in 1994. Its devastation would dwarf Northridge's, too.

Whereas the 1994 temblor killed 33 people and caused $40 billion in damage, flattening a section of Interstate 10 in downtown Los Angeles, the massive quake envisioned on the San Andreas could kill 1,800 people, injure 500,000, displace 270,000 from their homes and cause severe damage to 300,000 buildings.

Jones said the shaker is even expected to topple about five skyscrapers in downtown Los Angeles and northern Orange County.

Perhaps the most devastating feature would be fire.

Jones said scientists estimate that 1,600 fires would be ignited by the 90 seconds of shaking, and that 1,200 of those would be larger than a single fire engine could handle by itself.

Compounding matters, said North County Fire Protection District fire Chief Bill Metcalf, would be the inability of many firefighters to respond because some engines would be buried under piles of bricks and debris.

"Most of our fire stations were built in the '60s," Metcalf said.

Jones said that some fires would rage out of control, creating a massive conflagration that could wipe out 200 million square feet of buildings and cause half of the fatalities.

A total of $213 billion in damage would be left in the wake, she said.

Jones said the most intense jolt would be felt by 14 million people living and working in the Palm Springs area, San Bernardino, Riverside, Los Angeles and parts of Orange and Ventura counties ---- 14 times as many people as were rocked violently by the Northridge quake.

Damage would ripple

Residents of North San Diego County and Southwest Riverside County would be spared for the most part.

"However, there will be things you will have to deal with," Jones said. "There will be damage here."

For starters, the canal that delivers much of San Diego County's water from points north would be cut off and repairs could take weeks. Similarly, electrical power lines and pipelines that bring in gasoline and natural gas would rupture, she said.

Then there's the likelihood that tens of thousand of refugees from other Southern California counties would descend on the area, she said.

But getting around won't be easy.

The state's $6 billion campaign to fortify highway bridges since Northridge should prevent any freeway overpasses and interchanges from crumbling, she said. But that doesn't mean they will be passable.

And many city street bridges will collapse, she said.

"Travel is going to very difficult," Jones said. "And you're going to need to turn to each other for help because there isn't going to be anybody coming in for a while."

Because it is inevitable that a massive quake will occur before long on the San Andreas ---- there is a 59 percent chance it will happen in the next 30 years ---- people throughout Southern California need to start preparing for that eventuality, she said. And they need to rehearse what to do during the actual shaking.

Duck, don't run

During a question-and-answer period, Fred Luevano of Fallbrook, a member of the Fallbrook Fire Safety Council, wanted to know whether it was still advisable to duck beneath a desk or stand beneath a door jamb, as he remembered learning while growing up.

Yes, said Jones, it is still good to take shelter beneath a desk. But, no, she said, it is not good to stand beneath a door jamb because the frame may give way and the door may slam into you.

And no one should try to run to a family member in the next room.

"During an earthquake, trying to run is very dangerous to do," she said. "It will throw you to the ground."

During the Northridge quake, she said, 10,000 people were injured for that reason, and one woman lost her life trying to reach her children.

Answering another question, Jones said there is no such thing as "earthquake weather." It is a myth, for example, that quakes tend to rumble on hot, dry days.

"We may feel better saying earthquakes only happen in hot weather," she said. "But all that does is make us fee less nervous when it's cool."

Contact staff writer Dave Downey at (760) 745-6611, Ext. 2623, or ddowney@nctimes.com.

The Great Southern California ShakeOut

Billed as the largest earthquake drill in U.S. history, scientists and public officials are urging all Southern Californians to take part in a drill scheduled for 10 a.m. Nov. 13 to practice how they would respond in a magnitude 7.8 earthquake on the San Andreas fault.

The event is being called the Great Southern California ShakeOut.

Lucy Jones, chief scientist at the U.S. Geological Survey, said the goal is to get at least 5 million people to participate, including schoolchildren, businesses, civic and church groups, and families.

As of this week, she said, organizers had signed up 2,000 organizations representing 1.8 million people.

It is time, Jones said, for Southern California to learn something from earthquake-prone Japan.

"On Sept. 1 every year, the whole country pretends it is having an earthquake," she said.

Jones said those drills are one of the reasons why earthquakes there tend to kill relatively few people.

For information about the event, go to www.shakeout.org.