Chances of Big Aftershock in S.F. Predicted at 50%

SAN FRANCISCO — A dozen people remained unaccounted for today--one week after Northern California’s ravaging earthquake--and geologists predicted a 50-50 chance by Christmas of a major aftershock capable of causing considerable damage.

Survivor Buck Helm remained in very serious condition.

Demolition crews were taking down sections of Interstate 880 in Oakland for fear still-standing sections of the elevated, double-deck structure could tumble down like dominoes onto the 1 1/4-mile stretch that collapsed in the Oct. 17 quake.

The death toll rose to 63 with a coroner’s discovery of a 39th victim among the remains dug out of the rubble of I-880, which was the first elevated freeway built in California.

But Oakland police have been able to account for all but 12 of the 280 reported missing during the last week, Sgt. Greg Hughes said.

Still, rescue crews have not been able to locate other bodies in the rubble, where 55 cars were trapped at rush-hour--a number considered well below a normal Tuesday, possibly because of the scheduled third game of the World Series between the Bay Area’s two major league baseball teams.

A traffic officer reported that he had been “surprised at how light traffic was” five minutes before the quake, California Highway Patrol spokesman Thomas A. Noble said.

Four sections remain inaccessible to searchers. Digging will resume when the threatening sections are taken down, possibly by Thursday. There was no hope of finding anyone else alive, authorities said.

“The people that are (unaccounted for) I believe are responsible people. Many of their cars have been found on that interchange and for whatever reason their loved ones have not had contact with them,” Hughes said.

“We’ve sent officers out to check their homes, check their jobs, and every four hours we’re talking to the families,” he said.

The U.S. Geological Survey in Menlo Park issued a long-range aftershock forecast predicting over the next two months an 11% chance of a temblor of magnitude 6.0 or larger, and a 50% chance of one of magnitude 5.0 or larger.

The probabilities were based on statistics for California earthquakes, and not on actual measurements at the San Andreas Fault, USGS geophysicist Jim Luetgert said.

Engineers reported today that the toppled 50-foot section of the Bay Bridge is unrepairable. Officials for the transportation department said they hope to put up a new five-lane section on the lifeline across San Francisco Bay by Nov. 16.

Commuters left without the bridge and several stretches of freeway fared well again today--this time under partly sunny skies with only scattered showers, transportation officials said.

San Francisco Mayor Art Agnos called on the federal government to raise the maximum home rebuilding loan to $500,000 from $100,000, reflecting high housing costs in the region.

“One-hundred thousand dollars in South Carolina can make a big difference. It doesn’t here,” Agnos said.

Already, damage from the quake--estimated at more than $7 billion--has surpassed Hurricane Hugo.