Seattle has identified more than 1,100 buildings within its city limits that could collapse if an earthquake were to strike.
The 1,117 buildings in the city that need immediate structural enhancements were given three classifications of earthquake vulnerability, ranging from ‘medium’ (72 percent of them), ‘high’ (18 percent), and ‘critical’ (10 percent).
Data shows that schools make up 66 percent of the most vulnerable buildings labeled ‘critical’, often because they were built in the late 19th century or early 20th century.
The terrifying possibility of hundreds of buildings crumbling is being examined because Tuesday marked the 60-year anniversary since a magnitude 6.5 earthquake hit western Washington in 1965.
Three people in the Pioneer Square neighborhood were killed by falling debris, while four more people died from heart attacks linked to the earthquake.
The Nisqually earthquake in February 2001 measured a 6.8 on the Richter scale and killed one person while causing even more damage than the quake 36 years earlier.
Seattle is in a seismically active area known as the Cascadia Subduction Zone, and a flurry of earthquakes in recent months has experts worried a major event could be on its way.
That’s why Amanda Hertzfeld, the program director for Seattle’s Department of Construction and Inspections, is sounding the alarm before the worst happens.
There are more than 1,100 buildings in Seattle, according to city officials, that are at risk of collapsing or severe damage in the event of an earthquake
Pictured: Parked cars were rained with falling bricks from nearby building after a 6.8 magnitude earthquake hit Seattle on February 28, 2001
Hertzfeld explained to KOMO News that the more than 1,100 buildings marked as vulnerable ‘need to be retrofitted in order to be safer in an earthquake.’
A retrofit involves using steel to connect the roof to the walls and the walls to the floors.
Japan, one of the most earthquake-prone countries in the world, uses steel skeletons in its skyscrapers to add flexibility to rigid concrete that breaks apart during tremors.
Seattle has the same problem but is behind on fixing it. Although newer buildings must be constructed to be 20 to 25 percent stronger than previous standards, many older buildings are made of brick or concrete blocks and are not reinforced with rebar or steel beams.
‘Essentially, what an earthquake retrofit is is connecting the knee bone to the leg bone. It is connecting the building components together so in an earthquake, they don’t separate and the building doesn’t collapse,’ Hertzfeld said.
The data the city provided includes a trove of information on the buildings they want to reinforce, including their addresses, the year they were built and how many stories they are.
‘Certainly, Pioneer Square has the largest density of unreinforced masonry buildings in the city, but they are spread all throughout. So we have a number of them in Columbia City in the EU District, Old Ballard, essentially any of the quaint, charming, historic neighborhoods have URMs,’ Hertzfeld said.
When asked if safety instructions change depending on what type of building someone is in, Hertzfeld said no.
Pictured: Damage from the magnitude 6.5 earthquake in Seattle from 1965
So far, only five buildings have been retrofitted against earthquakes (Pictured: A damaged building from the February 2001 earthquake)
‘No, the instructions are still drop, cover, and hold on. You know, some people will say that they would want to run out of the building, but if you look at any of the pictures of URMs after an earthquake, it’s a pile of bricks on the sidewalk,’ she said.
‘And so if you are running out in an earthquake, you’re gonna be right where that pile of bricks is. So it’s still better to drop cover and hold on.’
The city does not mandate retrofitting because the process is extremely expensive, but Dr. H. Kit Miyamoto, an earthquake structural engineer, told KOMO that even small reinforcements can make a huge difference.
Seattle has marked five buildings on the list of more than 1,100 as being retrofitted, though the city’s long-term goal is to require all buildings do this.
‘We know that we can’t require these to be retrofitted until there’s some funding sources identified. Our program is continuing to advance and exploring options,’ she said, adding that some of those options included grants.
Hertzfeld mentioned that the city government supports Washington state’s House Bill 1810, which would make retrofits more affordable through property tax credits.
The bill did not advance this year, with Washington’s legislative session concluding on Sunday.
