West coasters: know your subduction zone (Cascadia Earthquake of 1700)

[Duer 157099]

Just found a fascinating publication on the USGS site called "The Orphan Tsunami of 1700" that describes a massive tsunami that hit Japan in 1700, but that was not preceeded by a felt earthquake.

Turns out the quake was off the west coast of America in the Cascadia subduction zone. New research indicates that this zone produces massive (>8) quakes every 270 years. Do the math. Last time was 1700.

http://en.wikipedia.org/wiki/Cascadia_Earthquake

http://pubs.usgs.gov/pp/pp1707/chapters/

edit to add this, from here: http://www.nature.com/news/2010/100531/full/news.2010.270.html

Ticking time bomb

Previous hazard estimates, based on the magnitude-9 earthquakes, had set the recurrence interval for earthquakes in the region at about 500 years, with a 10-15% chance of another in the next 50 years. But Goldfinger's study, by upping the total number of earthquakes to 41, has cut the average recurrence interval to about 240 years.

The last earthquake on the subduction zone was on 27 January 1700. Adding in the new earthquakes, and taking into account the statistical distribution of intervals between them, the next earthquake is overdue, and there's a 37% probability it will occur somewhere along the Cascadia fault in the next 50 years.

[ReggieVeggie]

1. I've seen several different documentaries about that

They found evidence in Cascadia that showed the effects of that quake

[CountAllVotes]

10. yep

The indigenous "myths" clearly state that everyone, animals included, all ran to the top of Mount Shasta to avert the massive flood.

It is all right there ...

:dem:

[Duer 157099]

15. There was a current one on NatGeo last night

I recorded it and watched it today. Yikes.

[tabatha]

2. And this is what the idiot Bilbray said

But Republican Congressman Brian Bilbray of San Diego cautions about jumping to conclusions when it comes to nuclear power plants in quake prone California. Bilbray says there are geographic and design differences between San Onofre and Fukushima.

"First of all," he says, "our earthquake fault is inland, over about 80-100 miles, so a major earthquake would not create the tsunami on the San Andreas the way the other ones," he says. "The big difference is that our backup systems are in the hillside, sealed up, and even if they were breached, are designed to operate underwater."

Bilbray points out that the Japanese quake was 10-times larger than the so-called “big one” in California, referring to the 1906 San Francisco earthquake.

~~~~~~~~~~~~

a) All quakes are not inland - there are many off the coast of CA
b) It does not mean that a bigger quake than happened at SF cannot happen in CA. The quake in Japan was bigger than anything they have ever had.

Republican logic.

[Duer 157099]

3. He has probably never heard of any fault besides San Andreas

Tunnel vision of a sort. Likely has no idea whatsoever of the huge looming threat that exists just off the coast of CA, OR and WA.

[kestrel91316]

4. I just found out that a leading expert on the subduction zone, in WA, is my assistant's uncle.

[tabatha]

5. Does he have any opinions on the next quake?

[WHEN CRABS ROAR]

9. We are overdue.

[kestrel91316]

11. One of his articles - May 2010:

http://www.dnr.wa.gov/AboutDNR/FieldNotes/Pages/20100504_walshnorman_earthquakestsunami.aspx

ETA: http://www.dnr.wa.gov/researchscience/topics/geologichazardsmapping/pages/earthquakes.aspx

More:
http://www.dnr.wa.gov/AboutDNR/DNRRadio/Pages/20091223_twalsh_tsunami_mapping.aspx

WA DNR Chief Geologist. Guess he's sort of a bigshot.....

[tabatha]

14. Thanks.

[Duer 157099]

7. Atwater? n/t

[kestrel91316]

12. Tim Walsh, Chief Geologist at WA DNR

[stevedeshazer]

6. Yeah. We know.

And we're totally unprepared.

Sincerely,

Oregon and Washington.

P.S. -- At least we don't have nuclear plants on our coasts.

[CountAllVotes]

8. that is an old old story

It is however very well documented in numerous "myths" from the indigenous people of this region. :grr:

:kick:

[WHEN CRABS ROAR]

13. I live in Port Orford, Or. on the coast and fifty miles from the Zone

We just had a town meeting three weeks ago about this very subject. We were told very bluntly to expect to be cut off from any help for at least three weeks. Only one two lane road runs north and south (101) with no roads going east and west. Only 1200 people live here and we wouldn't be a priority. Lots of evidence that these magnitude quakes have happened in the past. We know that it would be up to us for our own survival. But we're good at pulling together.