Seismic Safety Is Now Top Priority As Quake Damage Is Sorted Out
Experts call for overhaul or better enforcement of building codes
LOS ANGELES — EVERYTHING from new bridge designs to old sewer lines are being fundamentally reexamined in the wake of the damaging earthquake here.
As with major temblors in the past, seismic safety has vaulted to the top of the public and political agenda in California.
The probing has taken on a particular urgency this time because of the depth of the destruction and what it might portend if an even larger quake were to strike an urban area. (Preparation for quakes pays off, Page 14.)
Some are calling for significant changes in building codes and construction techniques. Others say only better enforcement and expansion of existing programs is needed.
Whatever ultimately comes out will depend as much on money as science. Seismic safety pivots on a curious, and not always compatible, mix of politics, economics, and engineering.
``The calls are more urgent and louder than ever before,'' says Tom Tobin, executive director of the state Seismic Safety Commission. ``We are not going to rewrite entire codes. But I think we will see some significant improvements.''
California, to be sure, is better engineered to withstand an earthquake than any other state. The 6.6 temblor that struck here would have done far more damage in many other places. Consider that the 6.8 quake that hit Armenia in 1988 killed at least 25,000 people.
That is little solace, however, to an area that just lost at least 57 people and where the damage is expected to top $30 billion. It also does little to ease public anxiety about the ability of the region's infrastructure to survive a magnitude 7 or 8 quake.
Nine days after the temblor rattled the San Fernando Valley and areas beyond, these are among the things that have been learned and what experts say still needs to be learned:
* Bridges. Early reports indicate fewer than 10 of the more than 2,000 highway bridges near the epicenter of the quake collapsed. That's the good news.
Most of the overpasses that ruptured were on older freeways that hadn't yet been brought up to current seismic standards. Thus, state transportation and other officials say, the need isn't to revamp existing codes but to finish a retrofit program that is already under way.
``The types of retrofits being implemented would almost surely have prevented the failure of these bridges,'' says Nigel Priestly, a structural engineering professor at the University of California in San Diego.
Two bridges that collapsed on the Simi Valley Freeway (Highway 118), however, were considered state-of-the-art. Some engineers theorize that a contributing factor in their failure was the flared design of the columns that supported the elevated roadway; this may have added to the bridges' stiffness.
But transportation officials contend that the spans, built over a previously unknown fault, would have severed anyway because of the force. Still, flared bridge designs are coming under new scrutiny.
* Housing. Early analyses indicate that newer buildings also fared far better than older ones. More than 11,000 dwellings have been declared unsafe so far.
One focus is on older apartment buildings that don't have plywood reinforcement in their walls. This has been spurred by the collapse of the Northridge Meadows apartment building, where the largest number of fatalities occurred. But there is still some dispute over whether that complex had reinforcing.
A 1973 law required plywood in the exterior walls of new buildings, to curb lateral movement. Some think it should now be instituted for buildings constructed before then.
A closer look is also being given to ``tilt-up'' buildings, pre-fab-like structures where concrete walls are lifted into place and attached to a wooden roof. As many as 100,000 of these, usually warehouses or small commercial structures, exist across the state.
Some Los Angeles City Council members want to expand retrofit requirements for unreinforced masonry and brick buildings as well.
* Utility lines. Images of broken water mains gushing like geysers, blacked-out neighborhoods, and gas-induced explosions have done nothing to instill public confidence in utility lines in fault-veined areas.
Experts say pipes and power grids can be engineered to withstand most quakes.
Lloyd Cluff, manager of the geoscience department of Pacific Gas & Electric, says there were gas lines in Armenia that didn't rupture even though there was a seven-foot shift in the ground. The quake here produced about a one-foot displacement.
Early inspections indicate many of the gas pipes severed last week were of World War II vintage. Firms will be under pressure to accelerate upgrade programs.
``My guess is utilities in the area will be relooking at their priorities,'' Mr. Cluff says.
Fixing old buildings and redesigning new ones takes money - something businesses and governments in recession-bound California don't have an abundance of. The next few months will tell how the clash between the pocketbook and preparedness turns out.