Research is underway into an earthquake early warning system that would allow buildings to be "stiffened" to cope with violent quakes just seconds before they occur, a Caltech seismologist said Friday.
Basically, the weak primary waves that begin a quake would be analyzed by instruments, which would send an electronic signal to flex a building for the violent secondary waves that would hit seconds later.
Hiroo Kanamori, one of the nation's leading earthquake authorities and a member of an international panel of scientists studying the idea, sketched out the proposed system Friday at a session of the Caltech Earthquake Research Affiliates, a group organized by the Caltech Seismological Laboratory. It was attended by dozens of Southern California disaster officials, both in the public and private sectors.
The early warning system would work differently than current ones, which detect shaking that starts far from an urban area and signals that the temblor will reach the city in a minute or two.
Such a system is in effect in Mexico City, which is often jolted by quakes that strike 200 miles away on the Pacific coast. With that system, sirens sound and residents are supposed to take cover, stop elevators, shut off the gas and so forth.
But in the system outlined by Kanamori, the warnings probably would be "site specific," or designed for a single building, which would be fitted with instruments to analyze the primary waves within three seconds. Characteristics of those waves would reveal whether a major quake is underway.
The system would then prepare the building by adjusting dampers designed to cushion the shock and by initiating magnetic systems--to be developed in the future--that would protect the building. It would also shut down utility lines and sound a warning.
Jim Goltz, an official with the state Office of Emergency Services, told the group that California might be prepared to fund a pilot project that would test the system in a high-rise building.
Goltz said the state and federally funded Trinet system of seismic recording stations has conducted a survey that indicated potential public interest, but also found that the state could face liability lawsuits should things go wrong. It might prove legally touchy if the state installed the system in some buildings, but not in others.
For the time being, if a system similar to Mexico's were installed in Southern California, it could warn Los Angeles officials of, say, a quake beginning in the Imperial Valley, said Egill Hauksson, a Caltech seismologist. Such a system is close to fruition, he said.
Kanamori cautioned that a building-specific system could take a century to fully develop.