Okay, time to do an assessment of the prediction which I posted here
Feb 22 at 12:14 UTC.
Normally I just post either a "hit" statement and details or a "no hit" statement and no details (because if nothing happened then there aren't any).
However, this time I'm in a bit of a quandary and so I'll post more detail than usual and let members give opinions.
This will be rather long but there are pictures to help. Hope you can all bear with me and get through this as I think it might be important.
In summary, my prediction was focused on three distinct but connected regions in the PNW of the USA, namely offshore and west of Eureka (Nth Cal),
Portland (Oregon), and the southern end of Vancouver Island (Canada) but also down into the nearby region around Seattle (Wash.).
They are distinct in distance but connected in terms of potential seismic activity, because studies of the coastal subduction zone there suggest the
Juan de Fuca plate runs under the land region for some miles, with Portland practically sitting above the edge of the 40-km depth zone, just as does
(Image from PNSN.org
That consideration covers two of the areas stated, but the other -- off-shore from Eureka -- is a horse of a slightly different but related color, so
to speak. The region I noted is near the southern boundary of the Juan de Fuca plate:
(Image source USGS.
This region tends to be pretty active, which is one reason why I said I'd not take much note of anything below a mag 4 in this case. I also figured
that if anything happened further up the line along the subducted section then it wouldn't be surprising to get movement there as well.
Now we get down to the nitty gritty. First, I must state that according to available data, there were no quakes within the stated range within the
specific regions I named. So, if I apply my usual rather tough standard to myself (as my posts in this thread will attest), this was a "no hit". If
people want it to be left at that, I have no problem with it.
On the other hand, near Lake Pillsbury (Nth Cal), at 04:49:41 UTC on Feb 23, there was a mag 4.3, and then at 04:50:14 (yes, just 33 seconds later),
there was a 4.2:
As a matter of interest these two quakes occurred about 16 1/2 hours after I posted my prediction.
However, here's where it gets really
interesting. There were apparently some foreshocks to these events and then a nice run of aftershocks. I
think it's easier if I just list them, breaking it into chunks of 5 quakes each for easier reading and counting. Note that the times are local to
California and not
map 1.6 2011/02/22 20:43:01 39.498N 122.943W 11.5 10 km ( 6 mi) N of Lake Pillsbury, CA
map 2.8 2011/02/22 20:44:27 39.496N 122.948W 11.9 10 km ( 6 mi) N of Lake Pillsbury, CA
map 2.9 2011/02/22 20:45:51 39.499N 122.951W 11.1 10 km ( 6 mi) N of Lake Pillsbury, CA
2011/02/22 20:49:41 39.499N 122.949W 12.8 10 km ( 6 mi) N of Lake Pillsbury, CA
2011/02/22 20:50:14 39.494N 122.957W 11.3 10 km ( 6 mi) N of Lake Pillsbury, CA
map 1.5 2011/02/22 21:04:27 39.499N 122.948W 11.3 10 km ( 6 mi) N of Lake Pillsbury, CA
map 2.3 2011/02/22 21:17:08 39.504N 122.953W 12.4 11 km ( 7 mi) N of Lake Pillsbury, CA
map 2.7 2011/02/22 22:14:46 39.493N 122.948W 11.1 9 km ( 6 mi) N of Lake Pillsbury, CA
map 1.7 2011/02/23 07:20:35 39.501N 122.954W 12.7 10 km ( 6 mi) N of Lake Pillsbury, CA
map 1.9 2011/02/23 07:22:16 39.492N 122.954W 12.5 9 km ( 6 mi) N of Lake Pillsbury, CA
map 1.6 2011/02/23 12:54:11 39.496N 122.945W 12.6 10 km ( 6 mi) N of Lake Pillsbury, CA
map 1.8 2011/02/23 15:34:54 39.502N 122.946W 12.6 10 km ( 7 mi) N of Lake Pillsbury, CA
map 1.6 2011/02/24 03:32:06 39.499N 122.948W 11.5 10 km ( 6 mi) N of Lake Pillsbury, CA
map 2.0 2011/02/24 07:46:54 39.501N 122.951W 11.5 10 km ( 6 mi) N of Lake Pillsbury, CA
map 1.4 2011/02/25 03:45:52 39.498N 122.957W 10.0 10 km ( 6 mi) N of Lake Pillsbury, CA
for the above 15 quakes is the SoCal Earthquakes and Data center (which
actually covers all Cali quakes). The list is updated regularly so get in soon if you want to check my data.
Because this was not an area I'd noted in the past as especially active I ran a search through NEIC, with the circle centered at 39.50 N and 122.95 W.
All the quakes are very, very close and within a fraction of that location. I used a circle with radius of 50 km (about thirty miles) as -- ditto --
they're all so close to that point.
Here are the results:
NEIC: Earthquake Search Results
U. S. G E O L O G I C A L S U R V E Y
E A R T H Q U A K E D A T A B A S E
FILE CREATED: Sun Feb 27 21:04:44 2011
Circle Search Earthquakes= 13
Circle Center Point Latitude: 39.500N Longitude: 122.950W
Radius: 50.000 km
Catalog Used: PDE
Date Range: 1973/01/01 to 2011/02/22
Magnitude Range: 4.0 - 10.0
Data Selection: Historical & Preliminary Data
CAT YEAR MO DA ORIG TIME LAT LONG DEP MAGNITUDE IEM DTSVNWG DIST
PDE 1973 11 12 033939 39.34 -123.36 18 4.4 MLBRK .D. ....... 39
PDE 1977 11 22 211552.50 39.45 -123.26 5 4.8 MLBRK 8D. ....... 27
PDE 1978 03 26 002704.40 39.19 -123.20 10 4.6 MLBRK 6D. ....... 40
PDE 1982 09 03 185823.80 39.56 -122.56 5 4.0 MLBRK 3F. ....... 34
PDE 1989 08 08 231506.10 39.48 -122.93 11 4.1 MLBRK 4F. ....... 2
PDE 1995 05 17 022913.69 39.81 -122.71 12 4.4 MLBRK 3F. ....... 40
PDE 2000 05 17 223207.66 39.39 -123.07 7 4.5 MwBRK 4FM ....... 15
PDE 2000 08 21 044513.50 39.33 -123.03 12 4.0 MwBRK .FM ....... 19
PDE 2001 02 02 230311.45 39.73 -122.81 11 4.2 MwBRK ... ....... 28
PDE 2001 03 11 101107.43 39.49 -122.95 17 4.1 MwBRK .F. ....... 1
PDE 2006 11 09 083813 39.36 -123.29 7 4.1 MwBRK 4FM ....... 32
PDE 2007 04 18 084222.33 39.47 -123.11 6 4.8 MwBRK 5FM ....... 13
PDE-W 2009 12 22 234043.92 39.78 -123.34 9 4.0 MwBRK 2FM ....... 45
You can confirm this data by going direct to the search page
According to the NEIC, there have been just 13 mag 4.0 or bigger quakes in that defined area since 1973 and up to 22 Feb this year. That's less than
one every two years on average. Only two in the past 38 years or so have been in virtually the same spot as the latest: one was about ten years ago in
2001 and the other way back in 1989. Also, there are no other examples of "twin" mag 4-plus quakes in the list. They're all singular events.
This place had two mag 4-plus quakes within one minute
, less than 24 hours after my prediction was posted.
Yeah, so what, you might reasonably ask.
Well, if you extend the 30 and 40-km-depth lines of that subducting plate just a little ways beyond their estimated end points, they pretty well
bracket the above region:
(Source image modified by me to add the obviously included details in red.
So, because this pair of mag-4-plus quakes are quite rare in that spot, I feel that this angle needs looking at. I had mentioned my concerns both with
Portland and the Van Island and Seattle regions based on the subducting plate's assumed location
. These two mag 4s and what followed are
basically just off the end
of that assumed line -- a line that is hundreds of miles long.
Is the Juan de Fuca's subducted section slightly longer than thought? Just maybe? Or is this just one of those odd events and it has no connection to
subduction at all? It could be, but I'd like your feedback. Thanks for reading.
edit on 27/2/11 by JustMike because: Typos and a bit of coding.