State geologists will use recently released earthquake simulations to better understand which areas and critical facilities are most at risk from a magnitude 9 quake.
The computer generated earthquake simulations of a magnitude 9 along the Cascadia Subduction Zone fault show how the energy from the quake could be released into the landscape. The scenarios track from various origins of the quake as it rips along the fault, which runs along the Northwest coast.
Fifty simulations were run on super computers by the University of Washington and the U.S. Geological Survey. A big piece of the magnitude 9 project was designed to get a more comprehensive handle on the impacts from a quake on the scale of the 2011 earthquake and tsunami which hit in northeastern Japan.
What the simulations do not show yet is what the shaking will be like. That depends on the different kinds of rock and soil the earthquake waves travel through.
"There’s so much work to be done to understand the geologic hazard in all of Washington," said Corina Forson, the chief hazards geologist for the Washington Geological Survey, which is part of the Department of Natural Resources.
"And we will absolutely be able to use that data and those simulations that they provided." she added. "And start looking at our earthquake and tsunami inundation models. And we need that level of detail for all the faults in Washington to understand what the hazards are and what the shaking intensity could be. And if ruptures here and there and propagates in different directions, what does that look like and how does that prove or disprove what we think we know? "
While the magnitude 9 project led by the University of Washington focuses on the Cascadia Subduction Zone and how to make buildings stronger and communities more resilient, the state has a broader job.
"Where are our schools located? Where are our critical facilities located, and what is their seismic hazard?" asked Forson. "And we have a current decision package in right now for two full time positions to study earthquake and tsunami hazards to make some more maps to help us get down to that level of detail. So we hope we can save lives."
DNR is submitting another request to the upcoming legislative session for $531,000 to hire more personnel to do the groundwork on the hazards. Beyond fiscal year 2019, the continuing requests would be around $480,000.
DNR geologists would continue looking at the vulnerability of schools where only five of the state's 39 counties have been assessed; completing tsunami inundation mapping, which is only 50 percent complete; assessing earthquake-triggered landslide hazards; and continuing to find data for liquifaction mapping. Liquifaction is where lose soils will turn soft, "liquifying" during earthquake shaking.
The only county where the maps are considered reasonably complete is Clark County in southwest Washington.