Northridge Quake 'writing On Wall' For California And U.S.

SAN FRANCISCO -- Last month's Northridge earthquake showed that even in cities with mandatory upgrade programs designed to mitigate damage, many buildings remain vulnerable to even moderate earthquakes, according to a leading earthquake engineer.

"It is an extremely difficult technical problem, as well as a major financial challenge, to protect people and property, particularly in older buildings," said Ian Buckle, Ph.D., deputy director of the National Center for Earthquake Engineering Research (NCEER) at the University at Buffalo.

Buckle, professor of civil engineering at UB, is an expert on how structures perform during earthquakes and how damage to them can be mitigated. He made his comments today in a session on advances in earthquake disaster mitigation during the annual meeting of the American Association for the Advancement of Science.

"If the situation is to be improved, two things are necessary," he said. "First, the existing building stock must be ranked and priority must be given to upgrading essential buildings, such as hospitals. Second, less costly, more effective ways are needed to make these seismic upgrades."

Research plays a major role in making retrofitting less costly, he noted.

"New technologies, such as base isolation, are not only reducing costs, but are also allowing retrofitted structures to perform even better than new buildings that meet today's code," said Buckle.

He noted that after the Northridge quake, the base-isolated University of Southern California teaching hospital in Los Angeles remained open and fully operational without suffering structural or nonstructural damage. Instead of being rigidly connected to the ground, base-isolated buildings sit on flexible bearings that isolate them from earthquake motions.

Buildings near the USC hospital suffered damage to both structural frames and their contents and several other hospitals in the area had to be closed to new patients or evacuated due to the earthquake, Buckle said.

The same base-isolation technology used on the USC hospital is now being applied to two historic California buildings, the U.S. Court of Appeals in San Francisco and the Oakland City Hall, he added.

"In both cases, base isolation was less expensive than strengthening by conventional techniques," he said.

Base-isolation technology and other promising new developments are the result of intensive research programs funded largely by the National Science Foundation at the State University of New York and the University of California.

"If earthquake risk is to be reduced in the U.S., these are the kinds of innovations that must be implemented," said Buckle.

However, he added, research alone is insufficient.

"Owners and custodians of the nation's buildings and infrastructure must be given incentives to adopt and implement these new technologies," he said.

He noted that such policies must be adopted throughout the U.S., even where earthquakes occur infrequently.

"Seismic risk is determined by two factors: the likelihood that an earthquake will occur in a given place, and the consequences to the community should that earthquake occur," he said.

Even in regions where the probability of occurrence is low, the risk to society may be high because consequences may be catastrophic, he explained.

He noted that this is particularly true in areas such as the East Coast, because cities like New York are unprepared.

"Time is of the essence if a disaster elsewhere in the country is to be averted," he said. "The Northridge earthquake is the writing on the wall, not just for California, but for the rest of the country."