UW scientist creates 50 simulations of the ‘Really Big One’

Project simulates how a 9.0 earthquake would affect the Northwest

Simulation parameters for the scenario that generated the most shaking for the Seattle area. (Erin Wirth/University of Washington/USGS)

PORTLAND, Ore. (KOIN) — A University of Washington scientist created 50 simulations of the “Really Big One” to show how a 9.0 Cascadia earthquake could play out.

The last significant earthquake, just north of Olympia 16 years ago, was felt in Oregon, Canada and Idaho, but the 9.0 would be hundreds of times stronger. The potential earthquake along the Cascadia Subduction Zone could affect coastal Washington, Oregon, British Columbia and northern California.

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The UW project was presented Tuesday in Seattle at the Geological Society of America’s annual meeting. The project was led by Erin Wirth, a UW postdoctoral researcher in Earth and space sciences.

Wirth’s project ran simulations using different combinations for three key factors: the epicenter of the earthquake; how far inland the earthquake will rupture; and which sections of the fault will generate the strongest shaking.

The study shows where an earthquake starts matters most. Like Seattle, Portland is built on a sedimentary basin, not bedrock, leaving the city more vulnerable to quakes that start further away.

“It’s several different models that they’ve run, lots of different scenarios and it gives us an idea of the spectrum for any particular earthquake rupture, any different set of scenarios, what shaking will probably look like in Portland,” said Dr. Ashley Streig, an earthquake expert.

One of the simulations shows an earthquake that starts off the northwest Washington coast that shakes the Seattle area with less intensity than in Portland when it hits around 2 minutes later. Another shows a scenario that’s worse for Seattle, with the quake starting off the southern Oregon coast.