Scientists detail impact of ‘Big One’

A real quake would yield different results from the scenario, which excludes possibilities such as fierce Santa Ana winds that could whip fires into infernos.

The scenario: The San Andreas Fault suddenly rumbles to life on Nov. 13, 2008, just after morning rush hour. The quake begins north of the U.S.-Mexican border near the Salton Sea and the fault ruptures for about 200 miles in a northwest direction ending near the high desert town of Palmdale about 40 miles north of downtown Los Angeles.

Scientists chose the scenario because it would create intense shaking in the Los Angeles Basin and neighboring counties — a region with nearly 22 million people.

The scenario will be released at a House Subcommittee on Energy and Mineral Resources meeting in Washington.

Here are the major elements:

— 10 a.m.: The San Andreas Fault ruptures, sending shock waves racing at 2 miles per second.

— 30 seconds later: The agricultural Coachella Valley shakes first. Older buildings crumble. Fires start. Sections of Interstate 10, one of the nation's major east-west corridors, break apart.

— 1 minute later: Interstate 15, a key north-south route, is severed in places. Rail lines break; a train derails. Tremors hit burgeoning Riverside and San Bernardino counties east of Los Angeles.

— 1 minute, 30 seconds later: Shock waves advance toward the Los Angeles Basin, shaking it violently for 55 seconds.

— 2 minutes later: The rupture stops near Palmdale, but waves march north toward coastal Santa Barbara and into the Central Valley city of Bakersfield.

— 30 minutes later: Emergency responders begin to fan across the region. A magnitude-7 aftershock hits, but sends its energy south into Mexico. Several more big aftershocks will hit in following days and months.

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Major fires following the quake would cause the most damage, said Keith Porter, of the University of Colorado, Boulder, who studied physical damage for the scenario.

The quake would likely spark 1,600 fires that would destroy 200 million square feet of housing and residential properties worth between $40 billion and $100 billion, according to the scenario.

Once the shaking stops, emergency responders would do a "windshield survey" that involves rolling through neighborhoods to tally damage and identify areas of greatest need, said Larry Collins, captain of the Urban Search & Rescue Task Force at the Los Angeles County Fire Department.

Collins said the scale of the disaster means firefighters would not be able to put out every flame.

"We're going to have to think about out-of-the-box solutions," he said.

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