USGS/Drudge: 5.6 Quake off Oregon-CA coast. At location of Future 9.0 Cascadia Subduction Quake.

Drudge Report, USGS, Oregon Live ^ | 24 July 2018 | RACookPE1978

[Robert A Cook PE]

USGS reported 11 earthqaukes (the largest a magnitude 5.6) off the Oregon coastline today, right at the Oregon-CA border on the Juan de Fuca rise associated with the subduction zone of the Pacific plates and North American plates. This area, the Juan de Fuca fault subduction zone, has been quiet since 1700 - when a magnitude 9.0 quake occurred dropping land as much as 2 meters (9 feet) over the entire 800 mile Vancouver-Washington-Oregon coastline. That quake in 1700 caused documented 10 meter (30 foot) high tsunami's recorded in Japan that crushed many villages and towns.

Many previous large earthquakes have been discovered using underwater records of huge landslides/mudslides at 300 - 350 year intervals up and down all of the river outlets on the Washington-Oregon coast. Indian verbal legends also report the 1700 earthquake, but no earlier oral records are known.

At today's 318 year interval (2018-1700), it's a little bit early to claim today's earthquake swarm is a pre-cursor to the very large subduction quake, but small pre-cursors are expected before such a large quake. On the other hand, sufficient movement of the Oregon-Washington submarine floor might reduce the magnitude of a single very large quake.

The last such subduction zone faults in a comparable underwater subduction zone include: the Good Friday Alaska quake in 1964 (mag 9.2), the Mexico City earthquake in 1985 (mag 8.1, 9500 dead, 100,000 homeless), the Chilean earthquake in 1960 (mag 9.5, 2500 dead, 2 million homeless) the Chilean earthquake in 2010 (mag 8.8), the Sumatra-Indonesian quake 24 December 2004 (230,000 dead and missing), the New Zealand quake 22 Feb 2011, and the recent Japanese earthquake in 11 March 2011 (mag 8, millions displaced, 10's of billions in damage).

Large Pacific Rim earthquakes are troubling: in the southeast corner on 27 February 2010, the southwest corner 22 February 2011, the northwest corner on 11 March 2011.

And today? Only the northwest corner (Alaska-British Columbia-Washington-Oregon) has not moved for hundreds of years.

[Robert A Cook PE]

I really don't want to hear about even medium energy earthquakes in this subduction zone. The last such quake in 1700 buried 800 miles of coastline with land movement and 30-40 foot tsunami waves.

Losses would make the 1906 "sideways" jerk of San Francisco's more widely known San Andreas Fault look tiny.

Worse, a large subduction zone earthquake causes massive tsunami waves that increase destruction thousands of miles away on other coastlines. A "simple" sideways movement of slip fault like the San Andreas does not cause the massive vertical movement of hundreds of square miles of underwater ocean bottom.

[Robert A Cook PE]

Bad news.
Let’s hope it is not a precursor of a larger quake.

[chief lee runamok]

California may be split three ways whether the courts allow it or not.

[Robert A Cook PE]

For details, read Cascadia's Fault - The Deadly Earthquake that will Devastate North America by Jerry Thompson.

My copy is from Kindle, paperback and hardback versions are available at higher prices. Very, very sobering details about the fault out there.

[Hildy]

THE BIG ONE IS COMING

[snarkytart]

Lets all hope for the safety of our American bald eagle nests that mostly reside on the west coast up to Oregon, other than that...um...good luck.

[Beowulf9]

Waiting to see in California is a whole different thing than waiting to see anywhere else.

[lightman]

The last such subduction zone faults in a comparable underwater subduction zone include: the Good Friday Alaska quake in 1964 (mag 9.2), the Mexico City earthquake in 1985 (mag 8.1, 9500 dead, 100,000 homeless), the Chilean earthquake in 1960 (mag 9.5, 2500 dead, 2 million homeless) the Chilean earthquake in 2010 (mag 8.8), the Sumatra-Indonesian quake 24 December 2004 (230,000 dead and missing), the New Zealand quake 22 Feb 2011, and the recent Japanese earthquake in 11 March 2011 (mag 8, millions displaced, 10's of billions in damage).

Large Pacific Rim earthquakes are troubling: in the southeast corner on 27 February 2010, the southwest corner 22 February 2011, the northwest corner on 11 March 2011.

Curious how all of these struck between late December and early April

[SunkenCiv]

5.6 isn’t even a quake in California. :^)

[the_daug]

depends! I was in San Dimas when a 3.8 hit Chino Hills. I was in a backyard of a house where two cul-de-sac butted. The swimming pools all did tsunamis. All the store were closed cause the quake cleared the shelves of merchandise.

[null and void]

ping

[R_Kangel]

....... Doesn’t the fact that there was a quake mean that there was actually pressure released ..... Or am I just a total idiot?

[vpintheak]

Plenty of bald eagles in Alaska!

[SunkenCiv]

:^) Hey, sounds like fun! ;^)

[crusher2013]

Was that in 2008?

The Chino Hills Earthquake was around 5.7

[R_Kangel]

"..... I was in San Dimas when a 3.8 hit Chino Hills. I was in a backyard of a house where two cul-de-sac butted......

..... Yes ..... The most Dreaded ... "San Dimas Caldera" .... I am still living in fear of that ancient foretold event .... Since I still live in the San Dimas area .... I live in fear .......

..... Just kidding ..... "Party on DUDE!!!" ....

[Fiji Hill]

The last such quake in 1700 buried 800 miles of coastline with land movement and 30-40 foot tsunami waves.

That one caused a tidal wave that hit Japan.

[Cold Heart]

Can’t it be both:)

[Equine1952]

We have a few bald eagles along the snake river in Idaho too. Oh wait Yellowstone is going to blowup. Better keep the ones in Alaska safe. You just never know.

[the_daug]

I hated that movie!