Anyone over age 25 or so who lived in or near the Bay Area on Oct. 17, 1989, probably remembers where they were at 5:04 p.m.
That was the day of the Big One, at least the biggest one—at magnitude 6.9—since the Great San Francisco Earthquake of 1906 tipped the scale at a magnitude 7.8, nearly 10 times stronger on the logarithmic movement magnitude scale.
For those who lived in the Bay Area, the most stunning scenes came from Oakland, where the Cypress Street viaduct collapsed, sandwiching cars between two massive slabs of concrete and a section of the Bay Bridge collapsed.
And for San Francisco residents, scenes of collapsed and burning buildings in the Marina district offered stark reminders of the hidden power that can be unleashed when massive sheets of rock, buried miles beneath the surface, suddenly come unstuck.
At least 63 people died from the quake, nearly 4,000 more were injured, and thousands were left homeless, their homes, apartments and the accumulated possessions of a lifetime smashed and in ruins.
“We’re much better prepared than we were in 1989,” said Susan Tubbesing, executive director of the Earthquake Engineering Institute, the Oakland-based professional association for the nation’s earthquake-focussed professionals, including engineers, geologists and public policy officials.
“Berkeley is one of the better-prepared communities in the Bay Area, and has the best record by far for retrofitting single-family homes,” she said.
The city offers a partial rebate of the property transfer tax assessed at the time of sale if earthquake retrofits are made. Tubessing said the incentive was responsible for safeguarding about four of every five residences sold since the program was put in place.
Another star in the Berkeley firmament is the University of California campus, which she said has conducted the most comprehensive structural strengthening and safety programs of any UC campus.
The campus also sits astride the Hayward Fault, which scientists of the U.S. Geological Survey (USGS) have identified as the most likely source of the next major Bay Area earthquake
Both Pacific Gas and Electric and the East Bay Municipal Utilities District have strengthened their systems since Loma Prieta, Tubessing said, and San Francisco is launching a similar program.
“Berkeley is clearly in better shape than most communities in the Bay Area,” she said.The city’s controversial soft-story ordinance, designed to strengthen apartment buildings with inadequate ground floor support, has made slow but steady progress with work on many buildings already complete, and other cities are following Berkeley’s lead.
Another perilous structure, the unreinforced masonry building, is largely a thing of the past, and most of the threatened structures have either been reinforced or demolished, she said.
“All the bridges in the state have also been retrofitted since Loma Prieta,” Tubessing said. One result is the current work on the Bay and Golden Gate bridges, while work on the San Mateo Bridge has already been completed.
Tubessing started work with the institute in 1988, a year before Loma Prieta gave her first-hand experience of the aftermath of temblors.
With funding from the National Science Foundation, her organization dispatches teams around the world in the aftermath of major quakes in search of greater understanding of what happens when the earth moves.
“We published an entire book on Loma Prieta,” she said.
The organization also maintains a Bay Area map, available online, showing the location of retrofitted buildings. Anyone with a building not listed can add the structure to the map, which is located at www.earthquakeretrofit.org.
UC Berkeley’s Pacific Earthquake Engineering Research Center (PEER) will host an all-day conference Saturday at the Mark Hopkins Hotel to discuss both the progress made since Loma Prieta and work that still needs doing.
The session runs from 8:15 a.m. to 4:30 p.m.
One major concern of organizers of the event, a group which includes the USGS, the San Francisco city and county governments and CalTrans, is the declining federal support for research on quakes and mitigation measures.
The Berkeley-based PEER is a coalition of 20 universities, joined by several consulting firms, and works to improve building design, evaluate hazards and devise effective public policy solutions for seismic problems.
In announcing the conference, PEER Director Steven Mahin offered his own assessment of the progress made since Loma Prieta.
“We’ve come a long way in 20 years, but we’re still not where we want to be when it comes to risk reduction in a major earthquake,” he said, calling for more action from local governments “so that the next big earthquake becomes a quickly recoverable challenge instead of a catastrophic disaster.”
PEER reports and research are available online at http://peer.berkeley.edu. One report, “Bracing Berkeley,” describes the campus seismic retrofit program: http://peer.berkeley.edu/publications/bracing_berkeley.html.