Look at the Depth on This One if It Doesnt Disappear!

so close to EAB .. hmmmm !!!!


http://quake.wr.usgs.gov/recenteqs/Quakes/ci10545741.html

URL posts dont seem to be working now SoCal :-(

TrishNrthrdgCA wrote:so close to EAB .. hmmmm !!!!


http://quake.wr.usgs.gov/recenteqs/Quakes/ci10545741.html

URL posts dont seem to be working now SoCal :-(

Here is the posting on the quake. I don't know if 25 miles deep is a lot for the faults of that area or not.
--------------------------------------------------------------------------------
Magnitude 1.4 - local magnitude (ML)
Time Sunday, February 21, 2010 at 11:00:09 AM (PST)
Sunday, February 21, 2010 at 19:00:09 (UTC)
Distance from March AFB, CA - 7 km (4 miles) NNW (336 degrees)
Highgrove, CA - 7 km (4 miles) SSE (161 degrees)
Riverside, CA - 8 km (5 miles) E (84 degrees)
Woodcrest, CA - 10 km (6 miles) NNE (33 degrees)
Los Angeles Civic Center, CA - 87 km (54 miles) E (97 degrees)

Coordinates 33 deg. 57.3 min. N (33.956N), 117 deg. 18.4 min. W (117.307W)
Depth 40.9 km (25.4 miles)
Location Quality Fair
Location Quality Parameters Nst= 21, Nph= 21, Dmin=3 km, Rmss=0.4 sec, Erho=4.9 km, Erzz=3.2 km, Gp=151.2 degrees
Event ID# ci10545741

Hi Polly. That is a little deep. Not sure how good my memory is, but I think the crust in that area in southern California is about 30 Km deep. The crust thickens eastward from about 20 km at the western margin of the California Continental Borderland to about 32 km in the eastern Transverse Ranges. Over most of onshore southern California, crustal thickness is 30 +/- 2 km. I suspect in that area it is about 25 Km thick.

I looked at the waveforms and they don't look very good. Don't be surprised if this quake is taken off the map when someone gets around to looking at it. Take Care...Don

Don in Hollister wrote:Hi Polly. That is a little deep. Not sure how good my memory is, but I think the crust in that area in southern California is about 30 Km deep. The crust thickens eastward from about 20 km at the western margin of the California Continental Borderland to about 32 km in the eastern Transverse Ranges. Over most of onshore southern California, crustal thickness is 30 +/- 2 km. I suspect in that area it is about 25 Km thick.

I looked at the waveforms and they don't look very good. Don't be surprised if this quake is taken off the map when someone gets around to looking at it. Take Care...Don

Thank you a lot Don for posting, I was hoping that you would see this post. I thought that 25 miles deep was a bit much for a 1.4 quake. Either this was a phantom quake of some sorts, or we may see something bigger there.

Hi Polly. We could see something larger as quakes can and do occur in the mantle. It's just that we don't see them that often here in Southern California. We do see them in Northern California, but then again the southern edge of the Juan De Fuca plate is in the area down to about the city of Redding.

It rather depends on who reads the seismograph whether the quake stays on or comes off.

The ANSS catalog does show some deep quakes within 200 miles of the one near March AFB. Take Care...Don

* catalog=ANSS
* start_time=1898/01/01,00:00:00
* end_time=2010/02/22,01:11:45
* minimum_magnitude=1.0
* maximum_magnitude=10
* minimum_depth=40
* maximum_depth=10000
* event_type=E
* delta=0 km to 320 km from (33.956,-117.307)

Date Time Lat Lon Depth Mag Magt Nst Gap Clo RMS SRC Event ID
----------------------------------------------------------------------------------------------
1984/06/07 18:09:59.76 35.6960 -120.0643 43.49 1.16 Md 10 259 17 0.19 NC 20358
2000/01/19 00:48:12.80 35.9144 -114.7613 45.64 2.23 ML 4 0.00 NN
2002/09/28 10:57:37.88 35.6958 -116.5476 60.04 1.32 ML 5 0.08 NN
2009/01/30 05:43:03.42 33.1587 -115.9715 79.74 1.88 ML 10 0.34 CI 14418260
2010/02/21 19:00:09.19 33.9558 -117.3067 40.93 1.37 ML 21 0.40 CI 10545741