1,000-plus buildings in Seattle could collapse in an earthquake

A city department is developing new requirements for earthquake retrofits in Seattle's most vulnerable buildings, and they could come before the City Council by the end of this year.

Why it matters: The Northwest is earthquake country , and seismic hazard modeling from the U.S. Geological Survey shows Seattle is at high risk of damaging shaking caused by earthquakes within the next 100 years.

Between the lines: A big earthquake would be especially damaging to Seattle's unreinforced masonry buildings, where brick construction predates 1945.

• While fireproof, those buildings contain no reinforcing steel, according to Amanda Hertzfeld, unreinforced masonry program manager with the Department of Construction and Inspections (DCI).
• In an earthquake, unreinforced masonry buildings are more likely to collapse or lose their facades, as one in New Zealand's Christchurch earthquake did in 2011, when it fell onto a city bus and killed 12 people.

By the numbers: By Hertzfeld's estimate, there are 1,100 unreinforced masonry buildings in Seattle and about 30,000 statewide. DCI maintains a list of Seattle's unreinforced masonry buildings — and whether they've been retrofitted.

• If you're a renter living in one of the buildings, reach out to your building's owner to see if it's been retrofitted. It's also a good idea to buy renter's earthquake insurance, said Hertzfeld.

Yes, but: We can do much more to prepare for earthquakes than buying insurance and filling up our earthquake kits.

• DCI is sending legislation to the City Council that would set new standards to retrofit these buildings, reducing the risk of collapse.

What they're saying: "It's really important that we prioritize the investment in retrofitting these buildings so that when that earthquake comes, we're able to recover much quicker and not have the doomsday scenario that is so often depicted," said Hertzfeld.

How it works: DCI released the first draft of their policy last year. Once code language is finalized — likely later this year — DCI will take it to city council to formalize into a city ordinance.

• If they own a property on the unreinforced masonry list, owners will need to retrofit their buildings to meet a new minimum standard. Then their status on the list will be updated.

Context: Despite their earthquake risk, unreinforced masonry buildings are historically and culturally significant to Seattle (with beautiful details like arched windows — a giveaway that you're looking at unreinforced masonry). and because of their age, they tend to be more affordable for renters.

• This is one reason why the standard is a minimum: The goal is to keep rents from rising when owners retrofit their buildings.

What's next: The City Council could take action on the final policy by the end of this year or early 2025.

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