From : W6VIO @ W6VIO To : QUAKE Date : 921216/1409 Msgid : BN 43193@W6VIO $43193_W6VIO Subject : S. Cal Weekly Rpt 12/3 - 12/9 [ W6VIO SYSOP NOTE: Sorry for the delay in posting this report. Cal Tech only released it this morning 12/16/92. They been rather busy! ] December 10, 1992 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. -------------------------------- This week's Report covers the time period from midnight Thursday morning, December 3, Pacific Standard Time, to midnight Wednesday night, December 9, Pacific Standard Time. Aftershocks of the Landers earthquake continue, 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 that happen to have made it through the data processing. There are 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. They are listed in the table. 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 times; if you want Greenwich Mean Time, add 8 hrs. to the Pacific Standard Time 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 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 Lucerne Valley 12/4 4:59 am 34 21.7 116 54.8 4.0 5 mi. SSE of Lucerne Valley 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 Lucerne Valley 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 ----- End of message 43193 from W6VIO @ W6VIO. ----- WD6CDN at W6VIO-1 [1008] =>