From: cowen@jade.ucdavis.edu
Newsgroups: ca.earthquakes,sci.geo.geology
Subject: Caltech Weekly Report, July 24 1992
Date: 24 Jul 92 18:26:47 GMT
Reply-To: cowen@jade.ucdavis.edu
Followup-To: ca.earthquakes
Organization: Geology Department, University of California, Davis

Here is the test of Caltech's weekly earthquake report. It, and the Postscript
map that accompanies it, can be reached by ftp at "seismo.gps.caltech.edu"
in the directory heirarchy "pub" then "ca.earthquakes". Last week's
inaccessibility was clearly a temporary glitch. I can't do the postscript
reposting for lack of time and buffer capacity. I've lightly edited the
text but left in everything crucial.
Here it is:
Weekly Earthquake Report for Southern California, July 16 - 22, 1992

Prepared by Kate Hutton, Seismological Laboratory,
(kate@bombay.gps.caltech.edu)
and Lucy Jones, U.S. Geological Survey
California Institute of Technology

	This document is a commentary on current seismic activity.  The 
	earthquakes discussed have been detected and processed 
	automatically.  All epicenters and magnitudes have been reviewed 
	to exclude obvious blunders; however, they must still be 
	considered preliminary.  For further information, please contact 
	the authors or the Caltech Public Relations Office at (818) 356-6326.

			--------------------------------

	This week's Report covers the time period from midnight Thursday 
morning, July 16, Pacific Daylight Time, to midnight Wednesday 
	night, July 22, PDT. Aftershocks the Landers earthquake continue, 
as they will for several months at least. The activity is still so 
high that we are unable to keep up	with the processing. 
We have included events of M2.5 or larger on the map, 
although many of them are automatic locations which may be 
somewhat less reliable than usual.
		Landers and Big Bear aftershocks continue. The emphasis this week, 
however, seems to be in the Barstow area, where a M4.4 and a M4.5 
were felt on Sunday night and Monday morning, respectively. 
As with the Big Bear events, these quakes stretch	the definition 
of the word "aftershock". Many may consider that they belong to a 
separate sequence, possibly triggered by the Landers quake. Other 
seismologists would call them aftershocks.
	In any case, had this whole sequence occurred in the 1930's when
	epicentral location quality was much inferior to what it is now,
	all would have been aftershocks, since we would not have been able
	to tell for sure that the location was different.
		The other event felt this week, M3.2, occurred 7 mi. SE of Ontario 
on Saturday morning. Regular readers of the Weekly Report will recall 
that Ontario is a fairly prolific source of small earthquakes. 
During 1990 and 1991, there were 25 quakes about M2.0 at this location.
		Table 1 lists only earthquakes of M3.0 or larger this week,	
due to the high level of activity. Times are local times; 
if you want GMT, add 7 hrs. to the PDT listed.

	Table 1
	-------
	Date  Time     N Lat.   W Long.   Mag

	-------------------------------------------------------------
         7/16  4:38 am  33 52.9  116 14.8  3.2  11 mi. N of Indio
         7/16  4:38 am  34  8.5  116 43.3  3.2  6 mi. ENE of Mt. San Gorgonio
         7/16  9:36 am  34 26.5  116 32.1  3.4  22 mi. NNW of Yucca Valley
         7/16 10:19 am  34 26.6  116 27.2  3.6  22 mi. N of Yucca Valley
         7/16  2:58 pm  34 56.3  116 55.3  3.6  6 mi. ENE of Barstow
         7/16  3:28 pm  35 14.2  116 53.9  3.1  8 mi. S of Goldstone (dry) Lake
         7/16  9:48 pm  35  8.2  116 49.8  3.2  15 mi. SSE of Goldstone	(dry)
Lake
         7/17 10:04 am  34 28.6  116 30.3  3.1  24 mi. N of Yucca Valley
         7/17 10:46 am  34  1.9  116 25.9  3.0  6 mi. S of Yucca Valley
         7/17  2:38 pm  34 29.9  116 32.2  3.0  26 mi. NNW of Yucca Valley
         7/17  5:06 pm  34  5.7  116 25.0  3.8  2 mi. SE of Yucca Valley
         7/17  5:36 pm  34  4.0  116 23.0  3.3  4 mi. SE of Yucca Valley
         7/17  6:01 pm  34  6.0  116 24.0  3.4  2 mi. ESE of Yucca Valley
         7/17  6:06 pm  34 55.9  116 54.9  3.0  6 mi. ENE of Barstow
         7/17  7:13 pm  34 58.5  116 56.0  3.3  7 mi. NE of Barstow
         7/17  9:00 pm  34 58.7  116 56.2  3.1  7 mi. NE of Barstow
         7/17 11:49 pm  35  1.9  116 58.4  3.0  10 mi. NNE of Barstow
         7/18  2:04 am  34 58.8  116 56.4  3.2  7 mi. NE of Barstow
         7/18  5:00 am  34 24.5  116 25.4  3.2  20 mi. N of Yucca Valley
         7/18  5:32 am  34 33.9  116 26.9  3.0  30 mi. N of Yucca Valley
         7/18  9:40 am  33 59.4  117 33.3  3.2  7 mi. SE of Ontario 	Felt
         7/18  1:09 pm  34 19.1  116 24.7  3.1  13 mi. N of Yucca Valley
         7/18  3:14 pm  34 16.7  116 43.8  3.0  7 mi. E of Big Bear City
         7/19  5:44 am  34 55.8  116 54.8  3.6  6 mi. ENE of Barstow
         7/19  9:22 am  34 32.4  116 32.5  3.0  23 mi. ENE of Lucerne Valley
         7/19 12:35 pm  35  0.4  116 47.2  3.1  15 mi. ENE of Barstow
         7/19  5:37 pm  35  1.8  116 58.3  3.4  10 mi. NNE of Barstow
         7/19  9:08 pm  34 11.9  116 25.9  3.9  5 mi. N of Yucca Valley
         7/19  9:48 pm  34 58.3  116 56.3  4.4  7 mi. NE of Barstow
						Week's 2nd largest; widely felt
         7/19 11:09 pm  34 58.1  116 56.4  3.1  7 mi. NE of Barstow
         7/19 11:16 pm  34  6.8  116 43.4  3.4  5 mi. E of Mt. San Gorgonio
         7/20 12:10 am  34 17.0  116 26.5  3.4  11 mi. N of Yucca Valley
         7/20  1:45 am  34  3.3  116 22.7  3.2  5 mi. SE of Yucca Valley
         7/20  3:35 am  34 58.7  116 56.5  3.5  7 mi. NE of Barstow
         7/20  6:13 am  34 59.5  116 56.9  4.5  8 mi. NNE of Barstow
						Week's largest; widely felt
         7/20  8:36 am  33 59.7  117 33.2  3.1  4 mi. S of the I10/I15
interchange
         7/20  4:04 pm                     3.5  Unlocated Barstow quake
         7/20 11:02 pm  34 57.2  116 58.3  3.0  5 mi. NNE of Barstow
         7/21  2:22 am  33  6.5  118 17.1  3.0  16 mi. S of Catalina Island
         7/21  5:21 am  34  1.9  116 22.3  3.0  7 mi. SE of Yucca Valley
         7/21  5:21 am  34 59.2  116 56.4  3.0  8 mi. NE of Barstow
         7/21  6:30 am  34  9.0  116 50.8  3.5  3 mi. NNW of Mt. San Gorgonio
         7/21 11:00 am  33 56.5  116 20.7  3.3  9 mi. E of Desert Hot Springs
         7/21  2:10 pm  34 13.1  116 46.3  3.6  5 mi. SE of Big Bear City
         7/21  2:12 pm  34 13.0  116 46.3  3.3  5 mi. SE of Big Bear City
         7/21  2:42 pm  34 56.6  116 38.7  3.0  21 mi. E of Barstow
         7/21  3:03 pm  32 48.8  118 28.5  3.7  7 mi. W of San Clemente Is.
         7/21  4:22 pm  34  8.0  116 36.1  3.6  9 mi. W of Yucca Valley
         7/21  9:13 pm  34 21.0  116 28.8  3.1  16 mi. N of Yucca Valley
         7/21 10:28 pm  34 34.4  116 32.7  3.0  24 mi. ENE of Lucerne Valley
         7/22 12:10 am  34 18.8  116 28.7  3.0  13 mi. N of Yucca Valley
         7/22 11:56 am  34 18.4  116 59.8  3.1  6 mi. NW of town of Big Bear

						Lake
         7/22  1:18 pm  36  0.3  118 22.5  3.0  26 mi. NNE of the town of

						Lake Isabella
         7/22  3:19 pm  34 59.8  116 57.2  3.2  8 mi. NNE of Barstow
         7/22  7:08 pm  34  8.1  116 51.9  3.1  3 mi. NW of Mt. San Gorgonio
         7/22 10:52 pm  35 37.8  117 38.4  3.0  1 mi. ENE of Ridgecrest
	-------------------------------------------------------------

Xref: sparky ca.earthquakes:753 sci.geo.geology:1722 rec.radio.amateur.misc:12713