Is Seattle Ready for the Next Big Earthquake?
New research the University of Washington’s M9 Project shows previous estimates of the type of seismic activity possible in the area understated the risk. Now, Seattle buildings over 240 feet tall will face tougher seismic standards in the future, but some worry about the buildings already standing. "Researchers found the sedimentary basin under the city can amplify the type of ground motion that’s hardest on high-rises by a factor of two to five — much more than previous estimates," Sandi Doughton reports for the Seattle Times.
Some suggest retrofitting older buildings that may be particularly vulnerable. "Even before the new shaking estimates, older high-rises were known to have a greater risk of serious damage and collapse than buildings that meet modern seismic codes," Doughton writes. Some older construction would have used welds that can fracture. "The city also does not require retrofits for old brick buildings, a seismic menace California tackled decades ago," Doughton reports.
Part of the issue with earthquakes near the city comes from the sediment basin underneath the city of Seattle. The basin can amplify and prolong shaking much longer than other environments would. Still, scientists point out that even though they can study the issue, it’s impossible to know how exactly an earthquake would effect the area, because there hasn’t been an earthquake along the Cascadia Subduction Zone for more than 300 years and there’s no way to be certain all the possible effects.