New simulations show best & worst places to be if major earthquake hits Pacific Northwest
SEATTLE - Researchers with the University of Washington have released new simulations revealing the best and worst places to be when a possible 9.0 earthquake hits.
Scientists believe the epicenter of the potentially catastrophic quake will be off the west coast between California and British Columbia, in an area known as the Cascadia Subduction Zone.
“What we've done differently in this research is we've run 50 computer simulations of what a magnitude 9 earthquake on the Cascadia mega thrust could look like,” said Dr. Erin Wirth, a University of Washington Researcher who now works for the US Geological Survey.
Wirth said until now, only three or four scenarios with the same data points have been run.
The results show that the intensity of shaking can be less in big cities like Seattle if the epicenter is fairly close.
“When the hypocenter starts closer to Seattle, even if it’s not right beneath it, the earthquake is progressing away from Seattle, so it's rupturing those offshore portions that haven't been ruptured yet,” said Wirth. “All the energy is directed off shore and that results in less severe shaking in Seattle.”
But, when the epicenter is located further away offshore, several hundred miles away, the shaking intensity in Seattle can be much greater.
“The earthquake is progressing toward Seattle and all those waves pile up along the way and that results in stronger ground shaking,” said Wirth.
The results also suggest that coastal areas would be hit hardest and locations in sediment-filled basins like downtown Seattle and downtown Portland would amplify the shaking waves.
“It would be good to be where the rock is hard,” said Wirth, suggesting being in the Olympic or Cascade mountain ranges which would likely see less shaking.
But, she also said that’s not guaranteed, because location of the epicenter can make a big difference.
The research was done as part of the National Science Foundation’s M9 Project. It’s an attempt to help people in the Northwest prepare for a massive earthquake.
Engineers at the UW are already using the simulation results to assess how tall buildings in Seattle might respond to shaking patterns.
Wirth will present her findings at the Geological Society of America’s annual meeting in Seattle on Tuesday.