Unpublished list reveals 3,400 San Francisco buildings may be at severe earthquake risk

A draft list of San Francisco concrete buildings reveals properties that the city says could be vulnerable to earthquakes and may need costly upgrades.

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The building list, which NBC News is publishing for the first time, provides a window into the sweeping cross section of San Francisco that could be especially vulnerable in a high-magnitude earthquake. Retrofitting the buildings so that they’re deemed safe could require billions of dollars and decades of work, structural engineers said. 

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The list is preliminary, so buildings could be taken off or added as city workers learn more about specific locations, and the San Francisco Office of Resilience and Capital Planning said that the dataset “will contain inaccuracies.” The list excludes single-family homes, public schools and buildings constructed after 2000. It’s not clear when the list will be finalized, but structures on the current list have one thing in common: They were built with concrete at a time before engineers fully understood how much steel or other reinforcement was needed to keep the concrete from crumbling while shaking. The concrete, referred to as nonductile concrete, breaks rather than bends in response to stress. 

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The only way to know a building’s safety level for certain is to have a qualified structural engineer evaluate it, the Resilience and Capital Planning office said. Engineers said the cost of that evaluation alone could be tens of thousands of dollars per building.

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