November 18, 1993 Weekly Earthquake Report for Southern California ------------------------------------------------ November 11 - 17, 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, November 11, Pacific Standard Time, to midnight Wednesday night, November 17, 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 284 this time. The bulk of the excitement this week was caused by the A-level alert at Parkfield, including a public earthquake warning for California, for a M6 at Parkfield. The alert was caused by a sequence of possible foreshocks under Middle Mountain, on the San Andreas, very near to the foreshocks of previous Parkfield earthquakes. See the Northern California Report for more details. The Parkfield alert expired early Wednesday morning, 72 hours after the M4.8 quake, without any larger earthquakes. In our own coverage area, the week's largest quake was a M3.4 near Lake Isabella, which did elicit a slight public interest. 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 8 hrs, to the Pacific Standard Time listed. Table 1 ------- Date Time N Lat. W Long. Mag ------------------------------------------------------------- 11/11 4:33 am 33 21.6 116 57.0 2.3 4 mi. W of Palomar Observatory 11/11 5:45 am 33 59.0 119 4.7 2.0 9 mi. WSW of Leo Carrillo State Beach 11/11 10:02 am 35 58.6 117 39.2 2.3 17 mi. ESE of Coso Junction 11/11 11:57 am 33 11.8 115 34.0 2.4 Obsidian Butte, 4 mi. SW of Niland 11/11 12:52 pm 34 9.0 116 25.9 2.0 2 mi. NNE of Yucca Valley 11/11 3:31 pm 34 29.7 116 30.5 2.9 26 mi. N of Yucca Valley 11/11 8:05 pm 32 35.8 115 47.6 2.0 15 mi. SE of Ocotillo 11/11 9:31 pm 35 40.6 118 19.4 3.4 8 mi. ENE of the town of Lake Isabella; FELT 11/12 12:24 am 35 40.6 118 19.7 2.0 " 11/12 12:49 am 34 54.2 116 41.9 2.3 18 mi. E of Barstow 11/12 11:32 am 33 58.4 117 4.8 2.2 6 mi. WNW of Beaumont 11/12 12:00 pm 34 57.0 117 1.0 2.1 4 mi. N of Barstow 11/12 11:18 pm 34 25.7 116 28.4 2.0 21 mi. N of Yucca Valley 11/13 12:09 am 33 59.5 116 58.4 2.1 4 mi. N of Beaumont 11/13 2:53 am 32 53.3 115 47.1 2.5 13 mi. SW of Westmorland 11/13 1:14 pm 35 57.2 120 28.5 3.0 6 mi. NW of Parkfield 11/13 1:48 pm 33 59.4 116 50.3 2.1 4 mi. NNE of Banning 11/13 3:01 pm 34 18.4 116 26.9 2.2 13 mi. N of Yucca Valley 11/13 6:04 pm 32 47.4 115 26.2 2.1 6 mi. E of El Centro 11/13 7:44 pm 33 50.4 120 7.8 2.1 7 mi. S of Santa Rosa Is. 11/13 10:10 pm 33 50.1 117 43.8 2.2 5 mi. SE of Yorba Linda 11/13 11:34 pm 33 42.5 116 46.6 2.2 4 mi. SW of Idyllwild 11/14 4:25 am 35 57.9 120 30.4 4.8 6 mi. NW of Parkfield FELT 11/14 4:29 am 35 56.8 120 30.4 2.7 " 11/14 4:34 am 35 59.1 120 30.7 2.9 " 11/14 4:53 am 35 56.8 120 28.0 2.8 " 11/14 12:17 pm 34 21.9 116 28.4 2.2 17 mi. N of Yucca Valley 11/14 1:10 pm 34 24.7 116 28.2 2.0 20 mi. N of Yucca Valley 11/14 3:13 pm 34 37.1 116 35.2 2.0 23 mi. ENE of Lucerne Valley 11/14 7:05 pm 35 59.1 120 32.6 2.6 6 mi. NW of Parkfield 11/15 2:32 pm 35 48.4 119 16.2 2.1 23 mi. SW of Porterville 11/15 4:16 pm 35 37.3 117 26.9 2.0 10 mi. SSW of Trona 11/15 8:14 pm 34 21.0 116 27.9 2.4 16 mi. N of Yucca Valley 11/15 8:21 pm 34 25.2 116 28.6 2.4 20 mi. N of Yucca Valley 11/15 8:21 pm 34 50.7 118 57.2 2.0 1 mi. NNW of Frazier Park 11/15 9:02 pm 34 54.9 116 46.5 2.3 14 mi. E of Barstow 11/15 10:47 pm 33 9.9 115 39.1 2.2 9 mi. N of Westmorland 11/15 10:49 pm 33 58.3 117 4.8 2.0 6 mi. WNW of Beaumont 11/16 4:40 am 33 9.9 115 38.9 2.4 9 mi. N of Westmorland 11/16 6:47 am 33 50.8 116 52.9 2.6 5 mi. S of Banning 11/16 4:47 pm 36 47.7 118 9.9 2.4 1 mi. E of Independence 11/16 6:08 pm 36 48.2 118 10.2 2.0 " 11/16 10:56 pm 34 28.5 116 31.5 2.1 25 mi. N of Yucca Valley 11/17 3:30 am 32 56.8 115 44.3 2.2 9 mi. SW of Westmorland 11/17 2:56 pm 34 35.2 116 38.9 2.1 19 mi. ENE of Lucerne Valley 11/17 3:35 pm 34 23.4 116 28.0 2.1 18 mi. N of Yucca Valley 11/17 9:22 pm 35 32.8 117 22.3 2.1 15 mi. S of Trona 11/17 9:58 pm 36 23.8 116 58.2 2.1 7 mi. WSW of Furnace Creek, Death Valley 11/17 11:00 pm 34 8.9 116 25.8 2.3 2 mi. NNE of Yucca Valley ------------------------------------------------------------- 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.