UCSD Jacobs School of Engineering
University of California San Diego

100 Years of Earthquakes—What We’ve Learned

April 18 is the 100th anniversary of the 1906 San Francisco earthquake, an opportunity to ask how the Jacobs School of Engineering and its Charles Lee Powell Structural Research Laboratories are contributing to the design and testing of earthquake resistant buildings, bridges, and other structures in California.

The Powell Labs contain the largest and busiest assembly of earthquake testing technologies worldwide. Our faculty and researchers are using these technologies to help ensure that buildings, bridges, and other structures in San Francisco , Los Angeles , San Diego , and other population centers will not fail in big earthquakes. (See pg. 6).Lessons learned not only from the 1906 San Francisco earthquake, but also from the1933 Long Beach, 1971 San Fernando, 1989 Loma Prieta, and 1994 Northridge earthquakes have helped us design and retrofit hospitals, schools, mid-rise concrete buildings, steel skyscrapers, and bridges, to name a few.

As chair of the California Department of Transportation's (Caltrans) Seismic Advisory Board, I am actively involved in ensuring that the latest seismic research findings are applied to all of the state's transportation structures, including some of the busiest bridges in the world. During the Northridge earthquake, bridge columns in the epicentral region that had been retrofitted with technology developed and tested at UCSD were undamaged, while seven bridges near the epicenter that had been identified as vulnerable and targeted for retrofit collapsed or were damaged beyond repair. Even one bridge failure can result in many deaths and a large economic loss to the surrounding area.

Caltrans owns 12,000 of the 24,000 bridges in California . It uses the Powell Labs to develop and test its bridge retrofit technologies, and it has successfully applied those technologies to all of its vulnerable bridges in seismically active regions of the state. The other 12,000 bridges in California are owned by cities, counties, railroads, and various public and private groups. Among these bridges not owned by the state, about 1,200were identified as needing seismic retrofitting. Still, about 40 percent of those, or more than 500 bridges, have not been retrofitted to date even though the federal government provides about 90 percent of the funds to do the work.

It's appropriate on the 100th anniversary of the San Francisco earthquake to remind ourselves that not all of the necessary steps have been taken to protect California from earthquake damage. No medium or large earthquake has struck the state's urban regions since 1994, and there is a danger of becoming complacent in our efforts to reduce seismic hazards. Even without a recent major seismic event close to home, Hurricane Katrina, the Pakistan earthquake, and last year's Asian tsunami are graphic reminders of the importance of preparing for the next natural disaster in California .

Frieder Seible

Related Links
Website: Powell Structural Research Laboratories
News Release: Engineers Announce Results of Second Northridge Shake of 7-Story Building
Video: CBS Evening News coverage of the 7-story shake test
Website: Englekirk Structural Engineering Center
In This Issue
Earthquake Safety Research
Los Alamos Lab contract expands Engineering Institute with UCSD
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