Sunday, March 13, 2011

U.S. subduction zone quake - it will happen here

On January 26, 1700, a magnitude 9.0 earthquake occurred along the Cascadia subduction zone off the coast of Oregon and Washington. It generated a tsunami that rolled across the Pacific an hit the Honshu region of Japan the next day, reaching 5 meters in height.

It was a mirror image of the 9.0 Japan quake and tsunami of two days ago.

And it is a geologic certainty that another Cascadia megaquake will strike the Pacific Northwest some time and we now have graphic evidence of what that means.

My colleagues in the Oregon and Washington geological surveys recognize this hazard and are heavily engaged in trying to understand the potential and mitigate the risks. But trying to prepare for an event that may not occur in the lifetimes of those who fund this work is often an uphill battle.

In Japan, they have a warning system that recognizes the P or primary waves of a major quake and sends out emergency warnings that the slower but much more damaging S (secondary) and later surface waves will be coming shortly. Many in Japan had a crucial 30-40 seconds warning. That can be enough time to shut down critical facilities or get to cover. The tsunami warning system gave residents 30-40 minutes in many areas to get to higher ground.

It's long past time to install similar warning systems in seismically vulnerable locations in the U.S.

Update: Geomika offers a review and comparison of West Coast quake hazards at


  1. Anonymous1:26 AM

    I agree, Lee. Unfortunately our tsunami warning system is - or may not have the funds. Yes, guess what's on the budget chopping block.

    This is sad news. We need to have our warning systems in place for disasters. The planet has taken quite a beating the last several years with quakes, three times now there have been ocean wide alerts. I don't think the quake activity, hurricanes and tornadoes are going to subside any time soon.

  2. We here in the PNW need to face some facts: we could easily end up like New Orleans. Unprepared for a disaster, no effective rescue, and no real resources to rebuild afterward. The idiots in charge just don't care what happens. They're too busy pretending it never will. That's an intolerable attitude for what's supposedly the greatest nation on earth, and I wish I knew how we could change it.

  3. Here is one way...we need leadership by geologists, by geographers/urban planners, by architects and by politicians. We need strong leaders to stand up and admit it is shear stupidity to rebuild in New Orleans much of which is BELOW SEA LEVEL!
    We need to wake people up to the fact that tens of thousands of lives and billions of dollars will be wasted if we rebuild on the coast of north Japan and on Haiti and then we have California, Seattle and Vancouver,B.C.!!! Geological landscapes can teach us all a lesson.