From: cowen@JADE.UCDAVIS.EDU
Newsgroups: ca.earthquakes,sci.geo.geology
Subject: Caltech Weekly Earthquake Report, week ending DEC 10, 1992
Date: 17 Dec 92 23:22:10 GMT
Reply-To: cowen@JADE.UCDAVIS.EDU
Followup-To: ca.earthquakes
Organization: Geology Department, University of California, Davis

Here is the text of the Caltech weekly report. It accompanies a postscript
map that I can't or won't re-post because it's a very big file. You can
ftp the text and map from seismo.gps.caltech.edu under successive
directories pub and ca.earthquakes. 
This week's report was delayed by the AGU meeting in San Francisco.
I've edited the text lightly, but the information is unaffected.
Weekly Earthquake Report for Southern California, December 3 - 9, 1992

Prepared by:  Kate Hutton, Seismological Laboratory
(kate@bombay.gps.caltech.edu)
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.

--------------------------------
Aftershocks of the Landers earthquake continued during the 7 days to 
midnight Wednesday night, December 9, PST, as they will for several years 
at least. The map includes a virtually complete set of earthquakes of M2.5 or
larger, plus many smaller ones: 571 in all.
The main action this week was another M5+ shock at the northern edge of 
the San Bernardino Mountains. This one registered M5.1, and occurred on

Thursday evening. The focal mechanism showed thrust along an ENE trending

fault, but no fault has been identified as yet, for either this week's or 
last week's Big Bear aftershock. The M5.1 could be considered a sort of
third-level nested aftershock. It was an aftershock of the November 27 
M5.4, which was an aftershock of the June 28 M6.3 (Big Bear), which was an
aftershock of the June 28 M7.4 (Landers). Furthermore, the M5.1 had some
aftershocks of its own.
A number of other small shocks were felt this week, some of them quite 
small. It is quite easy for a human at rest near the epicenter to feel a 
M2.5 to M3.0 quake. Although the aftershock sequence is declining more 
or less as expected, the table shows that there were still a substantial 
number of earthquakes in this size range. In other words, they are not 
news. However, every time a person makes an inquiry with a radio station 
about whether that 3 am twitch was an earthquake or not, a Public Relations
staff member and a seismologist are awakened. We would like to humbly 
suggest that people could wait until normal business hours to settle their 
bets as to whether it was or was not an earthquake.
Due to the high level of activity this week, we are only listing quakes of 
M2.5 and larger in the table. As usual, times are local; for GMT, add 8 hrs. 
to the PST listed.

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

	-------------------------------------------------------------
        12/3   6:45 am  34 16.9  116 46.3  2.7  4 mi. ENE of Big Bear City
        12/3  10:41 am  34 15.3  116 26.0  2.7  9 mi. N of Yucca Valley
        12/3   1:58 pm  34 19.9  116 54.7  2.9  5 mi. NW of Big Bear City
        12/3   3:12 pm  34 20.1  116 54.0  2.5  5 mi. NNW of Big Bear City
        12/3   3:36 pm  34 15.1  116 25.8  2.8  9 mi. N of Yucca Valley
        12/3   5:11 pm  34 20.1  116 54.1  2.7  5 mi. NNW of Big Bear City
        12/3   6:08 pm  34 22.1  116 53.8  5.1  5 mi. SSE of Lucerne Valley (LV)
Widely felt.
        12/3   6:13 pm  34 21.7  116 54.0  3.3  	"
        12/3   6:13 pm  34 21.5  116 55.3  3.2  	"
        12/3   6:15 pm  34 21.8  116 54.6  2.6  	"
        12/3   6:19 pm  34 22.3  116 55.0  3.0  	"
        12/3   6:34 pm  33 33.1  116 31.8  2.6  8 mi. E of Anza
        12/3   7:12 pm  34 21.5  116 54.7  2.9  5 mi. SSE of Lucerne Valley
        12/3   7:14 pm  34 21.8  116 55.4  3.1  	"
        12/3   7:25 pm  34 22.3  116 54.4  3.1  	"
        12/3   8:29 pm  34 21.3  116 54.5  2.7  	"
        12/3   8:35 pm  34 21.3  116 53.8  2.7  6 mi. NNW of Big Bear City
        12/3   8:38 pm  34 58.1  116 56.3  2.6  7 mi. NE of Barstow
        12/3   8:53 pm  34 22.0  116 54.8  2.5  5 mi. SSE of Lucerne Valley
        12/3   9:25 pm  34 22.6  116 55.1  4.5  	"  Felt.
        12/3   9:55 pm  34 21.7  116 55.2  3.0  	"
        12/3  11:22 pm  35 50.1  116 37.2  2.5  21 mi. WSW of Shoshone
        12/3  11:33 pm  34 21.6  116 55.5  2.8  5 mi. SSE of Lucerne Valley
        12/4   3:02 am  34 21.8  116 55.6  2.6  	"
        12/4   3:07 am  34 38.1  116 30.4  2.5  28 mi. ENE of LV
        12/4   4:59 am  34 21.7  116 54.8  4.0  5 mi. SSE of LV Felt
        12/4   8:20 am  34 21.8  116 55.3  2.9  	"
        12/4  10:00 am  34 22.7  116 55.7  2.9  	"
        12/4  10:46 am  35 31.5  117 25.8  2.5  17 mi. SSW of Trona
        12/4  12:51 pm  34  6.8  116 59.6  2.7  8 mi. SE of Running Springs
        12/4   1:52 pm  34 21.0  116 53.2  2.5  6 mi. NNW of Big Bear City
        12/4   2:09 pm  35 22.2  118 37.8  2.5  15 mi. NE of Arvin
        12/4   3:59 pm  34 21.3  116 53.8  2.6  6 mi. SSE of Lucerne Valley
        12/4   8:57 pm  34 21.9  116 55.6  2.7  5 mi. SSE of Lucerne Valley
        12/4   9:20 pm  34 21.8  116 55.3  3.2  	"
        12/4  10:14 pm  34 21.8  116 55.3  2.9  	"
        12/5  10:08 am  34 20.9  116 52.9  2.6  5 mi. NNW of Big Bear City
        12/5  10:28 am  35  3.6  116 59.4  3.2  11 mi. N of Barstow  Felt.
        12/5  10:42 am  34  0.7  116 18.7  2.6  10 mi. SE of Yucca Valley
        12/5   1:30 pm  34 21.9  116 55.4  2.7  5 mi. SSE of Lucerne Valley
        12/5   2:04 pm  34 21.5  116 54.3  2.5  	"
        12/5   6:40 pm  34  8.9  116 25.6  3.1  2 mi. NNE of Yucca Valley Felt.
        12/5   7:39 pm  34 21.1  116 53.1  2.6  6 mi. NNW of Big Bear City
        12/5   9:59 pm  34 22.0  116 52.9  2.5  6 mi. SE of Lucerne Valley
        12/6   1:34 am  36 26.2  120  3.9  2.5  25 mi. SW of downtown Fresno
        12/6  10:42 am  34 56.4  116 47.3  2.5  13 mi. ENE of Barstow
        12/6   2:35 pm  34 21.2  116 53.8  2.6  6 mi. NNW of Big Bear City
        12/6   4:17 pm  34 36.5  116 38.6  2.5  20 mi. ENE of Lucerne Valley
        12/6   4:49 pm  34 22.6  116 54.0  3.2  5 mi. SSE of LV, Felt.
        12/6   7:31 pm  34 21.8  116 55.7  3.1  	" Felt.
        12/6   7:33 pm  34 21.7  116 55.4  3.9  	" Felt.
        12/6   8:19 pm  34 16.8  116 41.8  2.6  8 mi. E of Big Bear City
        12/6   8:42 pm  34 21.4  116 55.5  2.7  6 mi. S of Lucerne Valley
        12/6  11:25 pm  34 25.3  116 42.2  2.6  13 mi. NE of Big Bear City
        12/6  11:50 pm  35  4.1  116 59.5  3.7  12 mi. N of Barstow
        12/6  11:58 pm  34 21.7  116 55.0  3.0  5 mi. SSE of Lucerne Valley
        12/7   6:41 am  33 32.1  118 24.4  2.8  13 mi. SSW of Pt. Fermin, San
Pedro
        12/7   9:03 am  34 23.1  116 27.7  2.6  18 mi. N of Yucca Valley
        12/7   9:17 am  34 22.4  116 53.6  2.6  5 mi. SSE of Lucerne Valley
        12/7  10:07 am  34 22.9  116 27.7  2.5  18 mi. N of Yucca Valley
        12/7   2:52 pm  35 14.7  118 36.4  2.7  11 mi. NW of Tehachapi
        12/7   4:14 pm  33 58.0  116 18.0  2.9  11 mi. E of Desert Hot Springs
        12/7  11:52 pm  33 57.8  117 49.4  2.7  5 mi. N of Yorba Linda
        12/8   4:30 am  34 59.8  116 57.0  2.8  8 mi. NNE of Barstow
        12/8  10:42 am  34 22.4  116 52.8  2.6  6 mi. SE of Lucerne Valley
        12/8  11:00 am  35 35.9  118 19.1  2.5  8 mi. ESE of the town of Lake
Isabella
        12/8  11:13 am  35 45.9  120 14.8  2.5  4 mi. NE of Cholame
        12/8  12:06 pm  34 30.9  116 32.0  3.0  25 mi. NE of Big Bear City
        12/8   7:39 pm  34 21.2  116 54.2  3.2  6 mi. SSE of Lucerne Valley
Felt.
        12/8  10:40 pm  34 22.4  116 52.8  2.7  	"
        12/8  10:53 pm  34 22.3  116 52.8  2.6  	"
        12/9  12:38 am  34 22.0  116 53.6  2.6  	"
        12/9   1:23 am  34 21.9  116 53.7  2.6  	"
        12/9   1:28 am  34 14.6  116 25.6  3.0  8 mi. N of Yucca Valley Felt.
        12/9  10:41 am  34 55.0  116 49.3  2.5  11 mi. E of Barstow
        12/9  10:55 am  34 33.6  116 31.0  2.6  25 mi. ENE of Lucerne Valley
        12/9  10:57 am  34 18.5  116 25.9  2.5  13 mi. N of Yucca Valley
        12/9  11:16 am  34 18.7  116 25.6  2.9  	"
        12/9  11:47 am  34 18.6  116 25.9  3.2  	"
        12/9   1:02 pm  34 56.9  116 55.1  2.5  7 mi. NE of Barstow
        12/9   4:02 pm  34 34.0  116 33.2  3.0  23 mi. ENE of Lucerne Valley
        12/9   5:03 pm  35 44.3  116 32.5  3.2  22 mi. SW of Shoshone
        12/9   5:06 pm  35 43.6  116 33.3  2.7  	"
        12/9   6:26 pm  34 58.3  116 56.0  3.4  7 mi. NE of Barstow
	-------------------------------------------------------------