More than 3,000 concrete buildings in San Francisco could be at high risk of collapse in the event of a major earthquake, according to a preliminary draft put together by the city government and obtained by NBC News.
The San Francisco Chronicle building on Mission Street, commissioned in 1924, was built out of concrete and it’s one of the older buildings on the city’s list for evaluation and possible retrofitting.
“That is a draft inventory, it is simply a list of older concrete buildings that have the potential for this non-ductile concrete vulnerability,” said Megan Stringer, president of the Structural Engineers Association of Northern California.
She heads the group of structural engineers working with the city to develop a plan to identify and retrofit older concrete buildings in San Francisco.
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She said some of those buildings, like Twitter's headquarters for instance, dating back to the 90s or older, don't have enough reinforcing steel inside the concrete to make them earthquake safe.
“We are working to fix these buildings, we know that it's an issue and we are working to fix that,” said Stringer.
Not every building on the draft list published on NBC News will need retrofitting, and some are listed by mistake, according to Stringer. The final draft is still in the works.
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In a statement to NBC Bay Area, Brian Strong, San Francisco's chief resilience officer noted that “the inclusion of a building on the list does not necessarily mean that the building is at a greater risk compared to other buildings from the same period. We look forward to sharing more information and reaching out to building owners and community members as we better understand which buildings may be most vulnerable,” he said.
The city is also working with housing rights advocates like Maria Zamudio, to ensure tenants won't be displaced by the retrofitting of some apartment buildings.
“Full and proper noticing for tenants, making sure that relocation is thought about,” said the organizing director of the Housing Rights Committee in San Francisco.
Come this summer, when a draft ordinance is published with plans for the concrete buildings, the public will get to weigh in before it's finalized.
Read Strong’s full statement below:
“The City is developing a Concrete Building Safety Program in collaboration with national experts and local stakeholders. The program bolsters San Francisco’s efforts to protect life and safety and make our City more resilient in the event of a major earthquake.
It is important to note that this list in its current form is a preliminary draft to get us started. The inclusion of a building on the list does not necessarily mean that the building it is at a greater risk compared to other buildings from the same time period. We look forward to sharing more information and reaching out to building owners and community members as we better understand which buildings are vulnerable.”