What You Know About “The Washington ‘Quake” Is About To Change

We've been hearing about "The Big One" for decades.  It's the earthquake that will lead to the tsunami and the eruption of Mt. Rainier that will devastate Washington State and Oregon.  The last time the Cascadia Subduction Zone (CSZ) created an event was January 27, 1700.

On that day, an ocean crossing tsunami struck the coasts of Japan and the Pacific Northwest after a megathrust earthquake (as large as 9.2) occurred.  Science was able to document the event through Japanese records, Native American tales, and geological evidence in the Northwest.

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We've been under the belief that when the next one happens the ground will shake with 100 foot waves potential hitting land.  Add in the possibility of lahars from Mt. Rainier and massive flooding, you're looking at situation where massive devastation could occur.  But it is what we have been led to believe accurate?

New Research Adds A New Wrinkle

The University of Washington led this latest research project into the CSZ and the results will force a change in predicting what might happen with "The Big One".  There is a fault line, called a megasplay fault and found near subduction zones, that is believed to play a role in the creation of tsunamis.  It is thought they can worsen a tsunami or even play a role in when it hits land.  It was also thought a megasplay fault was in play in the CSZ.

Based on new offshore mapping of the CSZ, it turns out there is no evidence that fault exists.  The findings were published on May 7th by USGS.  The bigger question is what does the new revelation actually mean?

It Doesn't Mean There Won't Still Be Devastation

If an event happens at the CSZ there will still be significant damage to the Pacific Northwest.  The biggest change is to the existing models with regard to tsunamis that were done with the assumption a megasplay fault existed.  The hazards presented by an earthquake and/or a tsunami will most likely be re-evaluated based on the new research.  You can read the full report by clicking here.

If you are interested in learning about the last Cacadia Subduction Zone Event in 1700, you can watch the video below featuring University of Washington's Harold Tobin who is also serves as Washington State's designated seismologist.

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