I knew that the Cascadia Subduction Zone was ripe for a big quake, but I had no idea that the whole fault has apparently been totally locked up for some time now. Scientists have studied the length of the fault and they can't detect any movement.

The stress can only be growing each day, and one day, all that pent up energy will be unleashed. Massive quake as well as a big tsunami. I read about it here.

It's stuff like this that makes living in EQ country interesting. You need to be prepared - always!

There is still so much we don't understand about earthquake zones in general, and Cascadia in particular. When I was an undergrad in the early 70's, the concept of Plate Tectonics was still relatively new, but geos had recognized that the west coast of OR, WA, and BC were a subduction zone. Even back then people were wondering why this subduction zone was seismically quiet. Only much later did research demonstrate that Cascadia did in fact have a record of major earthquakes.

In the past, the only available seismic array's were onshore. Since the portion of the subduction zone generating earthquakes is mostly offshore, these arrays could only detect quakes down to about M 3. We've known for decades that there was very little seismic activity down to that level. What is new is the ability to put sensitive Ocean Bottom Seismic (OBS) arrays right on the sea floor which can record for long periods of time and detect very small quakes. We now know that Cascadia is even quieter than we thought.

For a bit more general background, see Is 'eerie quiet' at Cascadia earthquake fault related to Nevada's swarm of tremors? (Note that the article says it probably isn't closely related to Nevada quakes.)

For more detailed into see the Cascadia Initiative website, and The Cascadia Initiative: A Sea Change In Seismological Studies of Subduction Zones (PDF).

I still chuckle, realizing I graduated in the late 50's with a minor in geology, and never once heard the phrase "plate tectonics." Back then geologists were into seduction, not subduction....

I also have to laugh. As of my mid-sixties geology courses in college, our professor was totally, and with utter contempt, dismissive of "plate tectonics" and "continental drift."

perhaps it is time for some fracking to release the pressure in increments.

Yup, a big one courtesy of the Cascadia is just a matter of when, not if. Interestingly, earthquake insurance seems slow to catch on here in the PNW. Same goes for retrofitting critical infrastructure -- but I suspect that will all change after a massive quake. And if any of the folks here have visited the OR coast, you've probably seen the tsunami evacuation signs in the low-lying communities.

A lot of faults are locked up right now. Quite a few of the major faults in LA are not moving very much, according to a recent news article. It is a concern to geologists.

There's no doubt that the whole West Coast is in for a pounding when these earthquake systems finally release all of that energy. Not sure that it will all happen at the same time. But if the Cascadia triggers, and later the San Andreas, the total damage on the West Coast will be astronomical.

Anyone who has got critical operations or industry needs to think about re-location.

Pete

I am not so sure about that, based on the SoCal experience. there are still numerous "soft story" apartments, the type responsible for significant loss of life in the 1994 Northridge quake that haven't been identified, let alone retrofitted. And that is right here in EQ Central.

Geezer in Chief.

Yes, I heard the same thing. True.
Also, quite a lot of historic buildings that have not been properly retrofitted, because the modifications would be too expensive or ruin the old architecture. LA is facing its share of real problems. and this does not include the fire hazard - which I think is actually the primary danger.

Pete