SOUTHERN CALIFORNIA SEISMOGRAPHIC NETWORK A Cooperative Project of Caltech and the U.S. Geological Survey November 20, 1997 Weekly Earthquake Report for Southern California ------------------------------------------------ November 13 - 19, 1997 Prepared by: Kate Hutton, Seismological Laboratory (kate@bombay.gps.caltech.edu) Lucy Jones, U. S. Geological Survey California Institute of Technology For further information, please contact the authors, or the Caltech Public Relations Office at 626-395-6327. For daily updates, call our Earthquake Information Hotline: 626-395-6977. -------------------------------- ***************************************************************** If you receive this Report by FAX and if you have recently had a change of AREA CODE, please notify us ASAP. We have no other way to know which fax numbers need to be changed!! Actually, if your area code is 818 and it HASN'T changed, it would be helpful to know that, too. ***************************************************************** This week's Report covers the time period from midnight Thursday morning, November 13, Universal Time (ie. UTC), to midnight Wednesday night, November 19, Universal Time. In local time, the period of coverage is from 4 p.m., November 12, Pacific Standard Time, to 4 p.m., November 19, Pacific Standard Time. We detected 145 earthquakes during the seven-day period covered. These Weekly Reports should not be used for archival purposes. Further data processing often changes the magnitudes slightly and, especially during times of high seismicity, sometimes changes the estimates of total seismicity. For the best earthquake catalog currently available, see: http://scec.gps.caltech.edu/catalog-search.html Although the seismicity was generally very low, there were two earthquakes of interest this week. The largest was a M4.7 (initially reported at M5.3) to the east of Big Pine, in northern Owens Valley. This quake occurred late Friday evening. It was widely felt in northern Owens Valley, and had a number of aftershocks. Although this quake is off the north edge of the map, we mention it because it was the week's largest. Another felt earthquake, a M3.6 near Lake Isabella, occurred about 23 hours prior to the M4.7. It was felt at Lake Isabella. The focal mechanism was 'normal', indicating tension in the crust. We should mention that Mammoth Lakes was also under- going a swarm during the early part of this week. The reader is referred to the Menlo Park report for further information on that. Table 1 lists the quakes this week that were M2.0 or larger in the central part of the coverage area. Times are local times; if you want Greenwich Mean Time, add 7 hrs to the Pacific Daylight Time or 8 hrs to the Pacific Standard Time listed. Table 1 ------- Date Time N Lat. W Long. Mag ------------------------------------------------------------- 11/12 10:49 pm 33 57.9 116 35.4 2.0 5 mi. S of Morongo Valley 11/13 2:47 am 33 28.8 116 26.8 2.7 13 mi. ESE of Anza 11/13 6:46 am 33 48.9 118 27.4 2.0 3 mi. NNW of Palos Verdes Point 11/13 10:53 pm 35 39.4 118 16.3 3.6 11 mi. E of town of Lake Isabella; FELT at Lake Isabella 11/14 11:31 am 32 47.0 116 48.7 2.3 8 mi. E of El Cajon 11/14 7:34 pm 33 13.5 116 6.0 2.2 5 mi. NNE of Ocotillo Wells 11/14 10:00 pm 37 14.0 117 52.9 4.7 22 mi. E of Big Pine; FELT in northern Owens Valley 11/14 10:42 pm 37 13.0 117 57.0 3.6 19 mi. E of Big Pine 11/15 12:19 am 34 58.3 116 56.5 2.2 7 mi. NE of Barstow 11/15 2:43 am 37 15.4 117 55.8 2.8 20 mi. ENE of Big Pine 11/15 3:24 am 37 17.1 117 48.5 2.2 27 mi. ENE of Big Pine 11/15 3:28 am 37 17.2 117 54.5 2.7 22 mi. ENE of Big Pine 11/15 4:40 am 37 16.8 117 52.8 2.2 23 mi. ENE of Big Pine 11/15 12:07 pm 34 56.9 116 56.0 2.2 6 mi. NE of Barstow 11/15 2:45 pm 37 17.2 117 50.8 2.4 25 mi. ENE of Big Pine 11/15 3:05 pm 37 12.1 118 1.2 2.3 15 mi. E of Big Pine 11/15 4:34 pm 37 15.2 117 50.5 2.7 25 mi. ENE of Big Pine 11/16 7:47 am 33 10.6 116 2.7 2.0 5 mi. ENE of Ocotillo Wells 11/16 4:10 pm 37 12.9 117 58.6 2.4 17 mi. E of Big Pine 11/16 6:49 pm 34 3.5 117 15.7 2.0 Under Loma Linda 11/16 9:25 pm 37 19.5 117 49.8 2.0 27 mi. ENE of Big Pine 11/16 10:25 pm 35 39.6 118 16.3 2.9 11 mi. E of town of Lake Isabella 11/16 10:38 pm 32 58.8 116 26.9 2.0 11 mi. SE of Julian 11/16 11:47 pm 36 11.5 117 8.4 2.0 3 mi. WNW of Telescope Peak 11/17 12:54 am 32 58.7 116 27.0 2.1 11 mi. SE of Julian 11/17 5:20 am 36 31.4 118 6.4 2.2 6 mi. SSW of Lone Pine 11/17 8:43 am 33 7.8 115 37.4 2.0 2 mi. SSE of Obsidian Butte 11/17 10:38 am 34 8.8 117 19.8 2.0 3 mi. NW of San Bernardino 11/17 10:42 am 34 8.8 117 19.6 2.2 " 11/17 2:43 pm 36 3.7 117 38.3 2.2 17 mi. E of Coso Junction 11/17 4:51 pm 34 36.1 116 38.2 2.0 20 mi. ENE of Lucerne Valley 11/17 7:52 pm 36 11.3 117 10.7 2.4 5 mi. WNW of Telescope Peak 11/17 10:52 pm 33 8.5 115 37.2 2.1 2 mi. SSE of Obsidian Butte 11/18 12:34 am 36 1.4 117 53.5 2.1 3 mi. ESE of Coso Junction 11/18 12:59 am 36 14.5 117 5.0 2.4 4 mi. N of Telescope Peak 11/18 5:48 am 32 10.5 115 22.6 3.1 34 mi. SSE of Calexico 11/18 12:59 pm 33 41.6 117 59.7 2.0 2 mi. E of Bolsa Chica Beach 11/18 11:03 pm 33 10.7 116 2.6 2.2 5 mi. ENE of Ocotillo Wells 11/19 1:52 am 34 0.2 116 24.2 2.3 6 mi. ENE of Desert Hot Springs 11/19 8:24 am 37 17.4 117 51.9 2.1 24 mi. ENE of Big Pine 11/19 9:19 am 34 6.9 116 50.5 2.0 1 mi. NW of Mt. San Gorgonio 11/19 12:11 pm 37 12.7 117 58.9 2.4 17 mi. E of Big Pine 11/19 1:06 pm 33 22.6 116 57.7 2.4 5 mi. WNW of Palomar Observatory 11/19 2:30 pm 35 47.3 117 37.5 2.2 11 mi. NNE of Ridgecrest -------------------------------------------------------------