World Series On Your Mind? Here's What The Game-Shaking '89 Quake Taught S.F.
It was just before Game 3 of the 1989 World Series when San Francisco's most devastating earthquake in modern history struck, and at least one structural engineer had a second-row seat for the 6.9 magnitude event.
"We were right behind the A's dugout, and things started to shake," Degenkolb Engineers Group Director and Senior Principal Jim Malley, who, knowing Candlestick opened in 1960, was quite concerned with its seismic resistance.
"I turned toward the upper deck and thought to myself, 'If things start getting out of hand, I'm going to jump over the rail and sprint out to second base as fast as I can.'"
Candlestick Park mostly withstood the event, which originated near Loma Prieta peak in the Santa Cruz Mountains about 60 miles southeast of S.F., but much of San Francisco did not. The Loma Prieta earthquake killed over 60 people, injured about 3,800 and caused over $5B in damages.
It also provided engineers and other scientists the knowledge — and other San Franciscans, the willpower — to initiate a more rigorous building code, which was eventually followed by still-ongoing seismic retrofits of thousands of buildings. The upshot, according to the city's structural engineers, is that while we're better off now than in 1989, there is still a lot of work to do.
"From a structural design standpoint, we've come a long way," DCI Engineers Vice President and Principal Jeff Brink said. "We've got more unique structural systems and requirements in the code to make sure the building is more seismically resilient, or 'ductile,' which is the ability of a building to absorb energy during an earthquake."
Those systems, like buckling-restrained braced frames to seismic base isolation, as well as ongoing retrofits of a growing number of San Francisco's older, soft-story buildings, would have mitigated the devastation wrought by Loma Prieta, an earthquake far smaller than the approximately 8 San Francisco's building code is based on.
"1989 stands out in everyone's mind, of course, and was a very unfortunate event for the Bay Area, but it was actually a smaller earthquake," Forell/Elseser Engineers principal Geoff Bomba said.
"It's what we call a service-level earthquake, like a 40-year event," Thornton Tomasetti Vice President David Ojala said. "The fact that any buildings were damaged in downtown San Francisco is not great performance. I'd even say it was a small event."
Loma Prieta was small but crucially insightful, according to Bomba, whose company led the base isolation of San Francisco's City Hall — an act both structurally and symbolically significant in a city with the unstable history of S.F. Case in point: the Marina District, which suffered disproportionate damage in 1989, with four people dying and 124 buildings destroyed or damaged.
"The Marina District is the stereotypical photo from '89. There was a lot learned just from that neighborhood," Bomba said. "The [soft-story ordinance] is a result of the experience we had with '89."
Other results are revolutions in high-rise seismic construction, like Jay Paul Co.'s 70-story, 181 Fremont project. Before finishing construction last May, the high-rise was awarded a REDi Gold rating by Arup for its ability to withstand a 475-year seismic event with minimum disruption.
To experts, it is one of the best buildings in downtown San Francisco from a safety-of-life perspective, according to Ojala. Though a New York Times story based on a U.S. Geological Survey report identifies 39 steel-frame at-risk buildings identified by the USGS, Ojala feels that retrofits on many of those buildings since mean calamity is not necessarily on the horizon.
"I don't think we're going to get a lot of injuries or deaths in that design earthquake, which is something a little smaller than the 1906 earthquake," Ojala said.
Nevertheless, he and other experts say the building code clearly falls short in designing for buildings — and the economy — to bounce back from such an event.
Resiliency, At Some Price
"The big limitation that we're dealing with right now is the building code," Bomba said. "Our building codes right now are just to protect the lives of the occupants. But there's going to be significant damage to the building."
Bomba cites a Federal Emergency Management Agency report published in December that identifies that very issue. A title on the second page of the FEMA document reads: "Building codes mostly aim to protect lives, not your business or investments."
The result is likely ample property damage and a potentially prolonged loss in economic output following the next big earthquake. For instance, in addition to killing 185 people, the 6.3 magnitude Christchurch earthquake that hit the New Zealand city in 2011 devastated its economy.
Consistent with the building code, only two buildings in Christchurch actually collapsed. Also not inconsistent with the code: 70% of downtown buildings in Christchurch were eventually demolished, and its central business district was effectively vacant for two years, according to FEMA's report.
For that reason experts see San Francisco commercial real estate's resiliency as the next, urgent frontier, though one that seems less so than buildings actually toppling.
"Resiliency is beyond saving lives to keeping the community thriving after a major event," Malley said. "That's really the hope now and the next step forward."
"Life safety is the target for most new buildings," Ojala said. "We don't design them to get you back home or back to work quickly, or to be repaired quickly or cheaply."
And partly due to the region's soaring construction costs, developers are reluctant to go beyond code, Ojala said, despite what he says Thornton Tomasetti quotes as at most a 2% increase in construction costs, if any increase at all.
A high-rise downtown might end up leaning toward a less affected building, forcing residents in not only the former but also the latter to evacuate.
"Or worse, there's at least one building I've looked at downtown that could lean over the electrical substation that powers all of downtown San Francisco," Ojala said.
For cases like that, many experts, like Magnusson Klemencic Associates Senior Principal John Hooper, questions and work remain.
"We have not directly tried to establish targets for functional recovery, which is how long it takes for you to be able to go back and use the building even if things still need to be repaired," Hooper said. "Is it days, weeks or months?"