NWNN: Research Shows Cascadia Quakes Sometimes Trigger San Andreas Fault

Here’s an article from the Northwest News Network about new scientific evidence that’s says that Cascade earthquakes have triggered San Andreas earthquakes several times over the millennia. How could disaster response be delayed and impaired if the entire west coast is impacted rather than just the north or south coast? Of course, the big question that remains to be answered is what magnitude of San Andreas quakes are triggered by Cascade earthquakes. The San Francisco metro area alone has around a million more people than the Seattle metro area. If a large CSZ quake triggered a large San Andreas fault quake, how far down the priority list would aid to outlying/coastal Washington towns fall if such a scenario were to occur?

New earthquake research to be presented by Oregon-based geologists
next week sounds like a B movie plot — a great earthquake along the
Pacific Northwest’s offshore Cascadia fault triggers another great
earthquake on the northern San Andreas Fault. In what may be a case
where life imitates art — or more precisely, where science catches up
to the fertile imaginations of Hollywood script writers — attendees at a
major earth science meeting in San Francisco will hear evidence that
this cascade of disaster happened many times over the past couple of

“I mean, Cascadia is big enough by itself,” said lead
researcher Chris Goldfinger of Oregon State University. “But if you add
in San Francisco and the North Coast, it is literally almost a grade B
movie scenario that people don’t want to think about that much.”

…Goldfinger said he found nine to eleven instances over roughly the last
3,000 years where a Cascadia earthquake seems to have triggered a San
Andreas quake. The vast majority of great Cascadia quakes during that
period have a correlation on the San Andreas Fault. He added that his
analysis of landslide traces found no evidence for the stress transfer
working in reverse — from south to north…

Click here to read the entire story at NWNN.

Marginally related:

TMIN: Mt. Rainier And The New Madrid Fault Zone Were Both Just Hit By Significant Earthquakes

City Journal: Off the Richter Scale: Can the PNW Prepare?

Here is another long article on preparing for a major CSZ earthquake from City Journal – Off the Richter Scale: Can the Pacific Northwest prepare for the cataclysmic quake that’s coming? Here is a choice excerpt:

…Local governments can’t possibly stockpile enough food to feed millions during a disaster; they aren’t, in fact, stockpiling anything. People will have to feed themselves until FEMA arrives, and the agency won’t be on the scene in a day, or even a week. Not a single road will be passable. An entire region 100 miles wide and 600 miles long will be ravaged. Many Americans have bemoaned the federal government’s response to Hurricane Maria on Puerto Rico, but we’ll have hundreds of de facto islands in the Pacific Northwest. Small towns will be cut off, especially in the coastal regions, battered by tsunamis and separated from major population centers by mountain ranges. So the states are partnering with the U.S. military to provide rotary-wing aid drops from Chinooks and Blackhawks onto track fields at schools and similar locations.

Local governments once told everyone to have at least three days’ worth of food on hand that can be prepared without gas or electricity. They have since raised the bar to two weeks. Is that enough? “I don’t trust the federal government to feed me on Day 15,” I say to Phelps. “I don’t either,” he replies. “I openly share your skepticism,” says Jeremy Van Keuren, community resilience manager at PBEM, “but we don’t want to scare people.” It’s hard to encourage citizens to be resilient if they find the prospect too overwhelming. “And the quality of aid we expect to receive at the end of that theoretical two weeks is questionable.” At least it takes four weeks to starve to death…

Emergency management officials know that being prepared for the traditional three days isn’t enough. They know two weeks isn’t enough, but they’re afraid people will tune out if they say to prepare for longer. Don’t be afraid to be prepared.  That people turn off isn’t news in the emergency management field. In the six year old video below, starting around the seven minute mark, an emergency management professional talks about how they’ve stretched preparedness to seven to ten days from 72 hours because that is all that people can handle. She says all the experts say that isn’t long enough.

Risk of Skyscrapers Collapsing in CSZ Earthquake Higher than Thought

New research from the University of Washington has determined that buildings in the Puget Sound lowlands and Willamette Valley will shake more than previously thought in a 9.0 Cascadia fault zone earthquake. Existing high-rise buildings may have a 20-25 percent chance of collapse.

Seismologists and structural engineers associated with the M9 Project at the University of Washington used supercomputers to run dozens of three-dimensional simulations of a magnitude 9.0 rupture of the offshore Cascadia fault zone. UW professor Jeff Berman said the modelling showed enhanced shaking in the vast, sediment-filled basins beneath the Puget Sound lowlands and Willamette Valley. Affected cities include Seattle, Tacoma and Everett, as well as Portland and nearby Tualatin, Oregon.

Berman said when “The Really Big One” hits, the geology of these basins could magnify seismic energy through what he called the “bowl of Jello effect.”

“If you shake a bowl of Jello, you can get the Jello to move a lot faster than the bowl,” he explained in an interview. “That is exactly what is happening in the basin. The ground motions are coming in and you’ve got this bowl that is not as strong and stiff as the surrounding volcanic rock underneath.”

Existing high-rise buildings that were built to minimum code standards have approximately a 20 percent, and maybe as high as 25 percent, probability of collapse, Berman said…


Oregon: No Coastal Hospitals Likely to Be Functional After Large CSZ Quake

A new Oregon State Department of Geology report concludes that “no hospital facilities are likely to be functional due to the expected severity of a magnitude 9 Cascadia earthquake and tsunami damage. Seismic vulnerabilities include building structures; non-structural components that are part of the building as well as equipment; and the limitations of on-site utilities such as power and water. Four of the eleven hospitals are located in the tsunami evacuation zone and face difficulties with tsunami planning. ” The hospitals were constructed before CSZ earthquake expectations were known, and suffere from inadequate seismic resilience.  There are worries about fuel and water accessibility post-quake in addition to the possible damage from the earthquake and tsunami. The hospitals are expected to take over three years to recover from such a quake.

Download the DOGAMI report here (pdf)