Had communities across California – including Napa – not had a program to reinforce older buildings, Sunday’s early morning earthquake likely would have damaged many more buildings, officials said.
Bricks and mortar fell when the 6.0-magnitude earthquake hit, but there were no fatalities and of the more than 200 people treated for injuries, only three were critical.
“I would think that had they had not gone through what they did you would see a significant amount of damage more — much, much more,” said Tim Strack, the chairman of the California Seismic Safety Commission. “So while what we see looks dramatic, it’s not near as bad as it would have been had they not gone through their retrofitting process.”
The timing of the earthquake, at 3:20 a.m. when few people were around, also worked to keep the number of injuries down, he noted. If it had occurred at 11 p.m. instead, for example, there would have been customers at restaurants and bars, and the debris that fell to sidewalks would likely have caused injuries, he said.
“However, if you look at the inside of the buildings, we do not see any catastrophic collapses,” he said.
At a press conference Monday, Napa’s director of community development, Rick Tooker, said it was too soon to tell if the program had been successful. Buildings were still being canvassed for damage, he said.
California has adopted stricter standards for new buildings following past earthquakes but many older unreinforced masonry buildings remain vulnerable. Some cities have required extensive improvements. Los Angeles mandated that all of its brick buildings be retrofitted, while San Francisco implemented a local ordinance after the Loma Prieta Earthquake in 1989.
“The program is more than 10 years old and I believe hit a 95 plus percentage completion rate,” said William Stawn, a spokesman for the San Francisco Department of Building Inspection.
Berkeley also has done extensive work in term of earthquake preparedness, but many other communities have done little in comparison, said Mary Comerio, a professor in the University of California, Berkeley, graduate school of architecture.
“There hasn’t been a huge effort,” she said. “People tend to forget, not just citizens but cities as well.”
Communities have had other priorities particularly in times of tight budgets, she said.
Strack said communities themselves needed to decide what amount of retrofitting they would require.
“These beautiful structures are not only part of our history but part of the communities and bind together us as a country,” he said. “So we want to try to find a way not only to save them for history’s sake but also to be able to utilize them.”
In some cases, brick walls are attached to ceilings and floors, in others, the strengthening is more extensive, for example building a steel structure inside the brick, Strack said. But even buildings that have been retrofitted may still be damaged in an earthquake, and may not be salvageable, he said.
“But if we didn’t lose any lives and people weren’t injured when they occupied the buildings, to me that’s a success," he said.
Retrofit standards as they were designed in the 1980s were meant to keep the buildings from collapsing and killing people, not to save the buildings for the future, Comerio said.
“The retrofits have helped,” she said. “They’ve helped reduce damage. They’ve helped save lives.”
For private buildings, owners are bearing much of the responsibility of the retrofits, she said. Communities could look at programs to help, whether by allowing owners to pass along some of the costs to tenants of apartments or some kind of tax breaks, she said.
“All those kinds of things are important and they will vary from locale to locale,” she said. “What a city like San Francisco or Los Angeles does would be very different than a small town or a suburb.”