November 4, 1993 Weekly Earthquake Report for Southern California ------------------------------------------------ October 28 - November 3, 1993 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) 395-6326. For daily updates, call our Earthquake Information Hotline: (818) 395-6977. -------------------------------- This week's Report covers the time period from midnight Thursday morning, October 28, Pacific Daylight Time, to midnight Wednesday night, November 3, Pacific Standard Time. The map includes a virtually complete set of earthquakes of M2.0 or larger, plus many smaller ones that happen to have made it through the data processing. There are 372 this time. It was a fairly nondescript week, which is fortunate, since we all had our minds on the wildfires. No earthquakes generated any public interest whatsoever. Two quakes near the Salton Sea are only slightly unusual. Both occurred last Friday morning: a M3.3 at the usual Obsidian Butte site west of Niland, and a M2.9 near North Shore, at the northern end of the Salton Sea. The Obsidian Butte site has produced many swarms over the last 5 years, including quakes above M3.0 several times a year. The North Shore event was more unusual, being about 3 km NE of the San Andreas fault. Earthquakes that close to the San Andreas are less comon, but they do happen, and this event was too small to cause any concern. The week's largest quake was the M3.5 near Eagle Mtn., or 17 mi. WNW of Desert Center, late yesterday afternoon. The table lists the quakes that were M2.0 or larger in the central part of the coverage area. Only M2.5 and larger events are listed for south of the U.S./Mexico border, and for the Coalinga/Parkfield area. For more information on the latter, see the Northern California Report issued by the U.S.G.S. in Menlo Park. Times are local times; if you want Greenwich Mean Time, add 7 hrs. to the Pacific Daylight Time listed, or 8 hrs, to the Pacific Standard Time. Table 1 ------- Date Time N Lat. W Long. Mag ------------------------------------------------------------- 10/28 4:51 pm 36 9.6 118 1.9 2.5 5 mi. W of Haiwee Reservoir 10/28 5:04 pm 34 58.0 116 58.0 2.0 6 mi. NNE of Barstow 10/28 6:29 pm 34 34.0 116 30.7 2.0 26 mi. ENE of Lucerne Valley 10/29 12:21 am 34 58.9 116 58.4 2.1 7 mi. NNE of Barstow 10/29 2:11 am 33 11.4 115 36.5 3.3 6 mi. WSW of Niland 10/29 8:41 am 34 9.5 116 25.5 2.3 3 mi. NNE of Yucca Valley 10/29 9:14 am 33 35.8 115 55.1 2.9 5 mi. NNE of North Shore 10/29 11:15 am 32 26.0 114 59.9 3.0 30 mi. SE of Calexico 10/29 11:59 am 33 23.5 116 18.2 2.0 10 mi. NNE of Borrego Springs 10/29 12:47 pm 34 9.5 116 26.0 2.3 2 mi. NNE of Yucca Valley 10/29 1:56 pm 34 10.6 116 26.1 2.0 4 mi. N of Yucca Valley 10/29 3:30 pm 34 35.7 116 36.8 2.0 21 mi. ENE of Lucerne Valley 10/29 4:00 pm 35 55.6 115 42.1 2.8 Calif./Nevada border, 32 mi. E of Shoshone 10/29 4:29 pm 34 9.4 116 25.9 2.6 2 mi. NNE of Yucca Valley 10/29 7:35 pm 34 11.5 116 49.1 2.0 5 mi. SSE of Big Bear City 10/29 7:54 pm 34 34.0 116 27.9 2.6 30 mi. N of Yucca Valley 10/29 8:11 pm 34 6.2 116 59.6 2.1 9 mi. SE of Running Springs 10/29 8:18 pm 32 21.7 115 3.4 2.5 33 mi. SE of Calexico 10/30 12:52 am 33 10.8 116 23.0 2.3 5 mi. S of Borrego Springs 10/30 6:06 am 34 6.3 116 59.7 2.2 9 mi. SE of Running Springs 10/30 8:02 am 34 19.4 119 14.7 2.3 4 mi. NE of Ventura 10/30 10:59 am 34 41.8 116 10.7 2.2 39 mi. N of Twentynine Palms 10/30 3:59 pm 34 57.9 116 57.5 2.1 6 mi. NE of Barstow 10/30 5:09 pm 35 59.8 117 55.1 2.4 3 mi. SSE of Coso Junction 10/30 7:54 pm 33 7.5 117 45.4 2.0 22 mi. SSW of San Clemente 10/31 5:04 am 34 6.1 116 59.7 2.0 9 mi. SE of Running Springs 10/31 6:46 am 35 44.5 117 35.8 2.1 9 mi. NNE of Ridgecrest 10/31 6:50 am 34 20.0 116 27.8 2.2 14 mi. N of Yucca Valley 10/31 10:31 am 36 18.2 120 20.9 3.1 11 mi. N of Coalinga 10/31 7:07 pm 34 11.3 116 49.2 2.1 5 mi. SSE of Big Bear City 10/31 9:06 pm 34 36.1 116 38.0 2.7 20 mi. ENE of Lucerne Valley 10/31 10:49 pm 34 27.5 116 30.2 2.9 23 mi. N of Yucca Valley 11/ 1 12:53 am 34 58.4 116 48.4 2.0 13 mi. ENE of Barstow 11/ 1 2:17 am 35 10.0 119 1.0 2.0 10 mi. NNW of the I5/99 interchange 11/ 1 4:18 pm 34 19.4 116 27.7 2.1 14 mi. N of Yucca Valley 11/ 1 4:46 pm 34 1.0 116 18.8 2.0 10 mi. SE of Yucca Valley 11/ 1 8:20 pm 34 58.3 116 56.6 2.1 7 mi. NE of Barstow 11/ 2 1:15 am 34 34.3 116 31.6 2.0 25 mi. ENE of Lucerne Valley 11/ 2 8:02 am 33 57.0 116 56.1 2.3 2 mi. ENE of Beaumont 11/ 2 1:38 pm 34 55.3 116 45.8 2.2 14 mi. E of Barstow 11/ 2 4:56 pm 32 37.3 115 48.2 2.9 13 mi. SE of Ocotillo 11/ 2 6:34 pm 33 31.4 116 34.2 2.3 6 mi. ESE of Anza 11/ 2 8:27 pm 36 18.1 120 21.6 3.2 11 mi. N of Coalinga 11/ 3 12:37 am 36 18.4 120 22.3 2.9 " 11/ 3 2:12 am 34 33.4 116 33.6 2.2 23 mi. ENE of Lucerne Valley 11/ 3 2:14 am 32 44.6 116 42.6 2.0 15 mi. ESE of El Cajon 11/ 3 4:14 am 35 55.6 115 43.1 3.1 Calif./Nevada border, 31 mi. E of Shoshone 11/ 3 4:15 am 35 52.2 115 39.4 3.4 35 mi. ESE of Shoshone 11/ 3 5:16 am 32 36.6 115 48.0 2.1 14 mi. SE of Ocotillo 11/ 3 5:16 am 32 35.0 115 47.3 2.1 " 11/ 3 6:46 am 34 8.1 117 43.3 2.3 2 mi. N of Claremont Colleges 11/ 3 7:45 am 34 17.7 116 26.4 2.3 12 mi. N of Yucca Valley 11/ 3 3:22 pm 34 22.6 119 17.8 2.4 5 mi. SSW of Ojai 11/ 3 4:36 pm 33 49.4 115 39.4 3.5 10 mi. W of Eagle Mtn. ------------------------------------------------------------- Figure. A map of southern California showing the earthquakes recorded during the past week by the Caltech/USGS Seismic Network. Major faults are marked, as well as the metropolitan areas of Los Angeles (L.A.), Palm Springs (P.S.), San Diego (S.D.), and Santa Barbara (S.B.). The circles denote the earthquakes, the size of the circle indicating the magnitude.