PORTLAND, Ore. – Portland faces mass casualties and billions of dollars in building damage if a large Cascadia Subduction Zone earthquake hits off the West Coast, according to an Oregon study released Thursday.
The Oregon Department of Geology and Mineral Industries said as many as 27,000 people could be hurt or killed in a magnitude 9.0 quake, though most injuries would be minor. Moreover, the study estimates up to 85,000 people could be displaced from their homes and building damage could top $30 billion.
The study’s lead investigator, John Bauer, said the study employs updated building and population statistics along with the latest mapping and modeling techniques. The region had been relying on estimates from 20 years ago.
“A Cascadia earthquake will happen,” Bauer said. “How well we prepare will make all the difference in how well we bounce back.”
The study focused on the three-county Portland metropolitan area, an inland region that’s home to more than 40 percent of Oregon’s population.
It says casualties would be much higher if the big one hits in the daytime, when more people are away from home. A 9.0 quake in the middle of the night would leave 4,400-10,400 injured or killed.
The report also examines the potential impact of a magnitude 6.8 quake along the Portland Hills Fault, which hasn’t produced a strong earthquake in thousands of years. Though the low-activity fault is less likely to rupture, its location beneath a large section of Portland would make a seismic event more catastrophic.
A daytime quake could leave 60,000 people injured or dead, the report said. More than a quarter-million people could face long-term displacement, and building damages might exceed $80 billion.
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