California Earthquake Scientists: Apocalypse Soon?

Video: San Andreas Earthquake Simulation On the web: daretoprepare.org

It'll be bad. Hurricane Katrina bad. Likely worse.

Thousands dead. Buildings collapsed. Freeways severed.

Scientists for the first time are figuring out in great detail just how bad it will be when the southern section of the San Andreas Fault, roughly between Palmdale and the Salton Sea, cuts loose.

"One of our goals is not to say, `We're all gonna die,"' said Lucy Jones of the California Institute of Technology, who is leading the effort. "It's, `Here's how you're going to die if you don't change anything."'

Scientists, academics, utility companies and emergency planners have jumped aboard the project so they can figure out exactly what will happen and how to reduce damage or at least be better prepared.

"What if a community decided to enact this measure on their water system? What if we could prevent the spill of petroleum product when a pipeline breaks?" said. "Our goal is to get the discussion going, and see how our choices are affecting our long-term survivability."

A detailed report is expected next spring. In November 2008 the state will use that information to create one of the most ambitious disaster drills ever undertaken.

While 300 miles of the northern fault ripped in 1906, killing an estimated 3,000 people in San Francisco, and the middle part shook during the powerful 1857 Fort Tejon earthquake, the southern section of the fault hasn't popped since the late 1600s.

There were six earthquakes in the 900 years before that, and none in the past 300, Jones said, meaning the most devastating disaster in 100 years is long overdue.

That's why scientists got funding last year to study a potential magnitude 7.8 quake that would originate near the Salton Sea and race 200 miles up the fault to Lake Hughes, just west of Lancaster.

What has surprised scientists is the level of destruction the earthquake would cause in Los Angeles, even though the fault is 60 miles away.

Though they're refining the computer models, the shock waves could turn west at the Cajon Pass and blast into Los Angeles.

(A link to animation showing how the shock waves are expected to behave is available at www.sbsun.com.)

That's about the same distance San Francisco was from the epicenter of the 1989 Loma Prieta earthquake. That magnitude 6.9 quake knocked down a freeway, severely damaged the San Francisco-Oakland Bay Bridge and killed 63 people.

A 7.8 quake would shake nearly 10 times harder.

And it would shake for minutes. The magnitude 6.7 1994 Northridge quake lasted only seven seconds but killed 60 people.

"The calculations of motion on a San Andreas earthquake surprised us with longer term motion than we expected," said Tom Heaton, a professor of engineering seismology at Caltech. "I think people will be unpleasantly surprised by how hard the shaking is."

Even though the shaking in Los Angeles wouldn't be as intense because of the distance, the city sits on a deep basin of sediment that will shake like a bowl of gelatin and prolong the event.

"There will be large low-frequency waves. The ground will shift 10 or 20 feet. The (high-rise) buildings will resonate back and forth, and the slow part of the ground motion is important to them," Heaton said.

Some researchers think it's possible some skyscrapers could collapse.

The scope of the disaster makes planning for emergency responders difficult at best.

Last year, when visiting the command center for firefighters who were then mopping up the Esperanza Fire, Gov. Arnold Schwarzenegger hailed the abilities of the state's firefighters and confidently proclaimed that a disaster on the scale of Hurricane Katrina could not happen in the Golden State.

But no matter how well-trained the state's firefighters and other emergency responders may be, Southern Californians who survive the "Big One" will need to make sure they have food, water and other supplies to stay alive without the aid of government agencies or relief organizations during the quake's immediate aftermath.