West Coast USA: Pay Attention, Cascadia May Be Ready to Rupture

reply to post by TrueAmerican


This is still somewhat experimental. I'm afraid I might have destroyed the evidence that it was recently listing non-human review. I just now pushed our latest solution onto the webpage, and now I see both events are human reviewed.

The system got the solution mostly right on the first pass. We checked that it was right, but did not submit our refined solution until we could check how the system would respond. By the time we had checked, we were worried that refining the solution would send in a second alert to the state authorities, confusing them. So we held off for 48 hours (and more) after which alerts are not sent.

The detail of the depth is somewhat controversial and unconstrained. We don't know the depth - it is off to the side of the array. It is not at the surface - that is implausible. It is likely either on the interface at 15 km depth or in the subducting slab at 25-30km depth. Our solution puts it deep, but I prefer the interface depth.

This situation is different than was the case when the event was really far offshore. There, the initial analyst misinterpreted it (missing the very late S waves), and I had to correct it several hours later when I noticed her mistake.

Let me know if this didn't answer your question.

Originally posted by JohnVidale
Our solution puts it deep, but I prefer the interface depth.

Ok, so this would imply you put out the overall solution by consensus? May I ask how many people are routinely providing the votes for overall consensus on depth? I have to admit though, that if you prefer another depth than that provided by the consensus solution, that says quite a bit about your character as the director of the PNSN. And that is to be admired.

This situation is different than was the case when the event was really far offshore. There, the initial analyst misinterpreted it (missing the very late S waves), and I had to correct it several hours later when I noticed her mistake.

So in this case, the S waves were clear enough to determine at the very least that you are SURE, those quakes were not out to sea....right?

Let me know if this didn't answer your question.

Yeah it did, to a degree, although perhaps some things are better left to private email- and you have been quite responsive there too, so thanks.

OK, so for the moment, let's say we operate under the assumption that those quake locations are correct. I mean ATS, now come on, we have no better source at this point to assess this. And you all see that there is controversy surrounding the depths of them from the very best source there is. So if we were to choose the consensus depth as well, and we have two quakes now at the subduction boundary depth, in addition to all the other activity, then hey. You all can look away or take note. Up to you all.

One thing's for darn sure though. Better keep the eyes open. But here: I'll play it safe, and just say that those quakes are probably just adjustments to the recent activity on the JDF/Gorda plates. No big deal.

Cause if I said what my real concerns were, I'd just get laughed at again.

reply to post by TrueAmerican


The depth issue is just how to report an uncertain number. We could say depth is between 0 and 50km depth, but context and analogy to previously studied events in the region provide some constraints, and the best number is a judgment call.

Yes, in each of the cases, the S waves enabled us to tell how far offshore was the earthquake.

If it is on the interface, that alarms us more than if it is not, but the alarm is mild - the overwhelming odds are nothing dramatic follows an M4 on the interface, no matter where it is.

Originally posted by JohnVidale
- the overwhelming odds are nothing dramatic follows an M4 on the interface, no matter where it is.

Well yeah, except let's not forget the overall context of when this is happening though. In the midst of considerable other activity off the coast. That's where the difference, and subsequent concern is for me. Too much going on too fast.

And another thing I have been thinking since learning of that separate massive fault under Seattle. If the CSZ goes in a big way with an M9, the chances of that fault under Seattle getting triggered by such an upset are going to increase dramatically. Could happen at all once, when the Seattle fault gets plastered by the incoming waves from the M9. So Seattle gets double pummeled. Massive shocks from the M9 start to wreak havoc, and then the fault under it ruptures, basically leveling the place.

:shk:

Nope, not me. Me stays over on the east coast. I'll take my chances with Mrs. Madrid.

reply to post by TrueAmerican


The Seattle Fault has broken once in the last 5000-10,000 years, while the Cascadia fault has broken 10-20 times. So the odds of it breaking soon could be a lot worse.

Originally posted by JohnVidale
reply to post by TrueAmerican

 

The Seattle Fault has broken once in the last 5000-10,000 years, while the Cascadia fault has broken 10-20 times. So the odds of it breaking soon could be a lot worse.

Right. Ok. Well then maybe I have it backwards. The Seattle fault goes first, and triggers the tsunami from hell when the CSZ follows suit.

?

OK, never mind. I do have a tendency to let the mind wander a bit too far.

Everybody's safe, and there won't be jack doodoo happen in Cascadia in our lifetimes. There. See? Everyone's happy now.

I live on Whidbey Island. I have been tracking the earthquake for the past two years. I felt my first quake in November 2010. If the Cascadia Subduction Zone creates an earthquake, I do not want to be here. I am about 99 miles from the ocean at the other end of the Straight of Juan De Fuca. I imagine the tsunami would be significant in the Puget sound. I leave here in September 2012 and return to Florida. Then I have the Canary Islands and hurricanes to worry about.

reply to post by squints2010

Magnitude
4.4
Date-Time
Wednesday, March 28, 2012 at 05:42:26 UTC
Tuesday, March 27, 2012 at 09:42:26 PM at epicenter
Time of Earthquake in other Time Zones
Location
43.636°N, 127.364°W
Depth
10.1 km (6.3 miles)
Region
OFF THE COAST OF OREGON
Distances
245 km (152 miles) WNW (285°) from Bandon, OR
248 km (154 miles) W (278°) from Barview, OR
252 km (157 miles) WNW (294°) from Port Orford, OR
332 km (207 miles) NW (310°) from Crescent City, CA
429 km (266 miles) WSW (242°) from Portland, OR
Location Uncertainty
horizontal +/- 22.8 km (14.2 miles); depth +/- 2.9 km (1.8 miles)
Parameters
NST=140, Nph=140, Dmin=260.5 km, Rmss=1.27 sec, Gp=202°,
M-type=body wave magnitude (Mb), Version=6
Source
Magnitude: USGS NEIC (WDCS-D)
Location: USGS NEIC (WDCS-D)
Event ID
usc0008rc3

earthquake.usgs.gov...

reply to post by berkeleygal


And here it is less than 20 minutes after your post showing as blue:



Are they generally changed that quickly?

Originally posted by jadedANDcynical
reply to post by berkeleygal

 

And here it is less than 20 minutes after your post showing as blue:

Are they generally changed that quickly?

That quake was listed as happening at 5:42, which, in the other persons post (at 6:28) makes it "in the last hour" but only until 6:42, when it was "in the last day" instead... and turned to blue.

reply to post by Bluesma


ach, sleep (or lack thereof) must be clouding my simple arithmetic ability.....

I kept thinking, "I know it's almost been an hour, but it should still be red..."

thank you and with that I bid ATS good night!

I live in the area and have been hearing about "the big one" since I was little. New stations haven't even been reporting on recent quakes in the area. If anyone thinks this is going to happen soon, I'd suggest you take a step back and stop worrying so much about it. When it happens no one is going to know and there's nothing they can do about it.

Point being, this has been circling the rumor mill for decades now and posting updates about minor quakes that aren not making headlines is pointless. Sorry if I sound rude, but all of this research is just a waste of time. For christ sake, the Seahawks scored a touchdown in a playoff game and it set off an earthquake from the crowd reaction. Nothing special is going on at the moment, sorry to burst your bubbles.

Originally posted by RicFlair
I live in the area and have been hearing about "the big one" since I was little. New stations haven't even been reporting on recent quakes in the area. If anyone thinks this is going to happen soon, I'd suggest you take a step back and stop worrying so much about it. When it happens no one is going to know and there's nothing they can do about it.

Point being, this has been circling the rumor mill for decades now and posting updates about minor quakes that aren not making headlines is pointless. Sorry if I sound rude, but all of this research is just a waste of time. For christ sake, the Seahawks scored a touchdown in a playoff game and it set off an earthquake from the crowd reaction. Nothing special is going on at the moment, sorry to burst your bubbles.

just makes me laugh, this kind of thinking. no scientific intrigue at all...
take a step back? dude, you living under a rock? a 9.0 rocks sumatra in 2004, and another in japan last year and you want us to just relax? lol...our region has the same capability and all of the evidence points to us being anytime soon.

i'd rather have some awareness if it ever hits than none.

Just thought I would post the past 5 days of episodic tremor and slip. Hopefully the combination of the whole world shaking and the ETS does not lead to action on the CSZ.

Courtesy of the PNSN tremor page (range set to 7 April thru 11 April, and overlay Color vs. Time)

reply to post by Olivine


And the red is all recent. We're wondering about that. The latest burst starts before the Sumatran event.

I wonder if all those large quakes so close together is a good thing or a bad thing. They all represent large bursts of energy that has been built up. The question I have is if these bursts of stored energy are like a safety release valve on an overheating boiler or if they are like cracks forming in a dam that is holding back enormous potential energy. Does anyone with more knowledge than I have an opinion on this?

reply to post by JohnVidale
Hi John- I am glad you stopped by. I was wondering about the 3.2 quake in Garratt Washington on 4/10. It is located near a fault line but is this causing concern to see a 3.2 in an area that is pretty quiet?

reply to post by Olivine


all of those red dots in the north by surrey/vancouver are recent quakes? I live on the coast

I thought I felt something a couple days ago while about to fall asleep, it felt like a boat very slowly rocking back and forth. at first I thought it was my heart beating in my body but it felt external after a bit.

there hasn't been any other noticeable shaking though. is there earthquakes happening all the time here?
I feel so ignorant about it now lol..

Source-USGS
Look at the depth of this one . . . right in the zone again.



It was preceded by this one:
Source-USGS



Then they moved them and changed the depth . . ..