December 28, 1993 Weekly Earthquake Report for Southern California ------------------------------------------------ December 21 - 27, 1993 Prepared by: Helen Qian, 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 Tuesday morning, December 21, Pacific Standard Time, to midnight Monday night, December 27, Pacific Standard Time. The Weekly Report is being issued early this week because of the Holidays. 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 311 this time. Southern California was quiet this week, a nice Christmas present for us at the Lab who would tather be home than working over the holidays. No earthquake this week was over magnitude 3, which only happens a few times a year. One Landers aftershock was felt, a M2.5 at 6:13am Monday, located 4 mi. SE of Yucca Valley. The swarm in Baja continues, albeit at a lower rate. 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 ------------------------------------------------------------- 12/21 1:48 am 34 26.7 116 29.6 2.0 22 mi. N of Yucca Valley 12/21 7:37 am 36 55.7 118 9.5 2.1 8 mi. NNE of Independence 12/21 8:48 am 32 59.7 115 34.9 2.3 3 mi. SE of Westmorland 12/21 9:08 pm 35 24.1 120 39.8 2.2 3 mi. WNW of Santa Margarita 12/21 11:03 pm 33 30.2 116 28.0 2.0 12 mi. ESE of Anza 12/22 2:04 am 32 22.4 115 24.0 2.5 21 mi. SSE of Calexico 12/22 3:40 am 35 17.9 117 40.1 2.0 22 mi. S of Ridgecrest 12/22 6:18 am 33 31.9 116 33.4 2.2 6 mi. ESE of Anza 12/22 7:21 am 34 55.0 116 55.0 2.2 6 mi. ENE of Barstow 12/22 9:17 am 33 13.0 119 10.9 2.3 18 mi. SSW of Santa Barbara Is. (highest pt.) 12/22 4:28 pm 34 8.9 116 25.9 2.9 2 mi. NNE of Yucca Valley 12/23 8:10 am 34 14.5 116 44.7 2.1 6 mi. ESE of Big Bear City 12/23 3:06 pm 34 9.0 116 26.4 2.1 2 mi. N of Yucca Valley 12/24 2:57 pm 32 22.0 115 20.8 2.9 22 mi. SSE of Calexico 12/24 12:14 am 34 34.6 116 29.2 2.5 31 mi. N of Yucca Valley 12/24 2:23 am 32 38.1 115 53.8 2.0 8 mi. SE of Ocotillo 12/24 8:21 am 34 23.1 116 28.0 2.1 18 mi. N of Yucca Valley 12/24 12:03 pm 34 25.2 116 28.1 2.5 20 mi. N of Yucca Valley 12/24 10:16 pm 34 1.0 117 6.7 2.5 4 mi. SE of Redlands 12/24 11:44 pm 34 27.2 116 29.8 2.3 23 mi. N of Yucca Valley 12/25 12:11 am 34 56.4 116 56.3 2.4 6 mi. NE of Barstow 12/25 6:09 am 34 58.3 116 57.0 2.0 7 mi. NE of Barstow 12/25 8:00 am 33 59.2 116 22.1 2.2 7 mi. ENE of Desert Hot Springs 12/25 10:19 am 34 6.1 116 25.9 2.1 1 mi. SE of Yucca Valley 12/25 10:29 am 34 6.1 116 25.9 2.0 1 mi. SSE of Yucca Valley 12/25 1:15 pm 34 5.7 116 26.4 2.5 1 mi. S of Yucca Valley 12/25 1:58 pm 34 2.2 116 19.2 2.1 9 mi. SE of Yucca Valley 12/25 4:39 pm 34 26.3 116 27.0 2.2 22 mi. N of Yucca Valley 12/25 9:27 pm 35 18.5 118 35.7 2.2 14 mi. NW of Tehachapi 12/25 10:16 pm 34 41.1 116 30.5 2.3 29 mi. NE of Lucerne Valley 12/26 12:22 am 34 22.1 116 28.2 2.1 17 mi. N of Yucca Valley 12/26 12:24 am 34 22.0 116 28.2 2.1 " 12/26 2:32 am 34 58.2 116 56.4 2.2 7 mi. NE of Barstow 12/26 2:42 am 34 22.0 116 28.0 2.4 17 mi. N of Yucca Valley 12/26 4:54 am 34 27.4 116 28.4 2.3 23 mi. N of Yucca Valley 12/26 8:56 am 35 0.3 116 57.6 2.2 8 mi. NNE of Barstow 12/26 10:01 am 35 19.9 119 17.8 2.2 15 mi. NNE of Taft 12/26 8:38 pm 34 46.7 116 17.3 2.1 35 mi. SSW of Baker 12/26 11:38 pm 36 0.7 120 1.1 2.4 20 mi. ESE of Coalinga 12/27 2:11 am 35 2.1 117 0.0 2.2 10 mi. N of Barstow 12/27 5:56 am 33 47.7 118 34.5 2.2 8 mi. W of Palos Verdes Point 12/27 6:13 am 34 4.4 116 23.0 2.5 4 mi. SE of Yucca Valley 12/27 6:42 am 34 15.2 116 26.1 2.0 9 mi. N of Yucca Valley 12/27 10:15 am 33 58.3 116 21.5 2.0 8 mi. E of Desert Hot Springs 12/27 10:54 am 33 6.0 116 37.7 2.2 2 mi. NW of Julian 12/27 10:54 am 34 34.5 116 34.7 2.0 22 mi. ENE of Lucerne Valley 12/27 3:21 pm 36 5.8 119 34.6 2.3 22 mi. SW of Visalia 12/27 4:39 pm 34 35.8 116 37.7 2.0 20 mi. ENE of Lucerne Valley 12/27 9:28 pm 34 0.8 116 20.3 2.6 9 mi. SE of Yucca Valley 12/27 9:45 pm 34 1.2 117 7.0 2.3 4 mi. SE of Redlands ------------------------------------------------------------- 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.