Sunday, December 28, 2014

More Notes on Tsunami Policy

A bit more of a follow up on my previous two posts: tsunami-policy-newport-Oregon and geologic-consent-and-civilization.
Chris Rowan contemplates the 10 years ago Sumatra Quake and tsunami (highlyallochthonous/sumatra-10-contemplating-the-power-of-tsunami)  and put up this USGS image of giant quakes.
It is a good reminder of the past and how much we have learned about giant subduction earthquakes and tsunamis since. It is also illustrative as to why there was a lag in subduction zone earthquake policy and planning in the Pacific Northwest. Outside of a few locations, these risks have been greatly under appreciated or in many cases completely unknown. And even where there was an appreciation, the mechanics were a complete mystery.

Giant coastal quakes and tsunamis were well known to afflict Chile, Japan and Indonesia. But the cause was not known and there was essentially no correlation between those far off places and the Washington State coast.

The Alaska quake of 1964 was important in that it took place shortly after the new concept of plate tectonics had become part of our understanding of how geology worked. As Rowan points out George Plafker's post 1964 Alaska Quake research radically altered our understanding of great quakes, subduction zone seismic events, and tsunamis. The great quake in Chile shortly before the Alaska event also impacted those interpretations.

What this meant for Washington State was that we began to realize that the Pacific Northwest coast was fronted with a tectonic alignment that matched other places around the world that had a history of giant earthquakes and tsunamis.

But the table above hints at what might be the cause of complacency and a lag in understanding and planning; there are big gaps between these large earthquake events. We went for 40 years without a mega thrust 9 earthquake anywhere in the world. Hence, it was hard to appreciate the destructive forces. In addition, the Pacific Northwest had no history of these events (Excepting the oral histories of First Nations Peoples). There was a debate of sorts for some time that giant mega thrusts may not be a risk here as we had no history of these sort of events.  

Brian Atwater went to the outer Washington State coast looking for the features observed in Chile and Alaska and found evidence of mega thrust faulting and over time he and many others have found clear evidence that giant quakes and tsunamis are part of the Pacific Northwest coastal landscape (see HERE for one site of that evidence). Atwater and others work shows that we have mega thrust quakes like Chile, Japan and Sumatra (

From a policy and planning perspective, we have some catching up to do with this relatively new understanding. The USGS and State Geology divisions in Oregon and Washington  have been working on educating the public and providing hazard maps. University researchers have made many advances in our understanding.

Emergency Planners have recognized the risk in most communities, and that recognition is evident with efforts to minimize the deaths and deal with the after event challenges. A lot of those efforts began before the big quakes in Sumatra and Japan. But in many communities emergency planners will tell you a lot more will need to be done with the populations already living in harms way. Oregon State governor has put $100 million into seismic safety in the next budget cycle. Plans are in the works for building escape centers on schools in danger zones in Washington State.

Then there is the development planning part of this equation. The fact that Oregon State University would be planning and advocating for a major structure within a known significant tsunami hazard zone does raise questions as to local, state and federal policies regarding funding development that we know will be destroyed catastrophically. While state and federal dollars are transferred to in-danger communities to mitigate the risks for areas of communities in harms way, more thought should go into where development investments are expended.

As atquake notes, "At the very least, learning from Sumatra (and Tohoku) is simple: don’t build high occupancy buildings in a tsunami zone, particularly when they’re on fill and have limited evacuation options". This is a policy position Washington State and Oregon State need to adopt.

For the thoughtful discussion of this policy issue as shout out to
Chris at,
Lockwood at,
Chris at atquake
and Oregon Public Radio.


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