SOUTHERN CALIFORNIA SEISMOGRAPHIC NETWORK A Cooperative Project of Caltech and the U.S. Geological Survey March 26, 1998 Weekly Earthquake Report for Southern California ------------------------------------------------ March 19 - 25, 1998 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. -------------------------------- ****************************************************************** THIS IS THE LAST SOUTHERN CALIFORNIA WEEKLY EARTHQUAKE REPORT. Frequently updated comments on current seismicity, and more extensive reports on noteworthy earthquakes, can be found on http://www.trinet.org/ There is a link to a California seismicity map, with a full list of events, at http://www.scecdc.scec.org/recenteqs/. If you have problems locating the information that you need, send e-mail to kate@bombay.gps.caltech.edu. Southern California epicenters and magnitudes are now updated as soon as they go through the interactive analysis phase of the data processing. This can be immediately, or several days afterwards, depending on the amount of activity and the time of day. Just think, now you don't have to wait until Thursday for the final earthquake parameters! ****************************************************************** This week's Report covers the time period from midnight Thursday morning, March 19, Universal Time (ie. UTC), to midnight Wednesday night, March 25, Universal Time. In local time, the period of coverage is from 4 p.m., March 18, Pacific Standard Time, to 4 p.m., March 25, Pacific Standard Time. We processed 350 earthquakes for the seven-day period covered. For the text of today's report, let me quote from the web site: ------------------------------------------------------------ 09:00 PST, Wednesday, March 25 There was a ML3.0 quake near the Garlock Fault, 12 mi. NNE of the town of Mojave, at 1:53 pm yesterday. The Garlock Fault is a left-lateral strike-slip fault that separates the Tehachapi Mtns. and the southern Sierra from the Mojave Desert. It has produced M5+ quakes in historic times, the latest being the ML5.7 Mojave earthquake on July 11, 1992, which was located 3 miles to the east of yesterday's epicenter. Yesterday's quake seems to have been a loner; no aftershocks. ------------------------------------------------------------ 09:28 PST, Tuesday, March 24 The largest quakes in our area last night were M2.3's. One occurred at 3:48 am, in the Coso Range sequence, and the other at 3:51 am in the Victorville area. Needless to say, because of the size, neither was felt. There was also a couple of M2.2's near Borrego Springs at 12:38 am. Henceforth, I am not going to update this Web page for an earthquake smaller than M2.5, unless someone feels it. ------------------------------------------------------------ 13:00 PST, Monday, March 23 The most recent quake of interest was a ML3.2 at 10:23 am today, located in the Santa Ynez Mtns., 4 miles NNE of Carpinteria. The focal mechanism was thrust. So far, no-one has called us to indicate that the quake was felt. It is not, by the way, a Northridge aftershock; the epicenter is too far west. ------------------------------------------------------------ 09:50 PST, Monday, March 23 We didn't really have any earthquakes worth mentioning this weekend. The largest of the insignificant ones, however, were: a M2.5 in the Coso Range sequence at 6:15 pm on Saturday, and a M2.3 Landers afterschock at 12:08 am on Sunday (i.e. just after midnight). ------------------------------------------------------------ 13:48 PST, Friday, March 20 The largest quake inside our Network in the past 24 hours was a 2.0. ------------------------------------------------------------ 16:01 PST, Thursday, March 19 The largest earthquake in the past few days was a M3.8 in the Coso Range (Little Lake) sequence that started last week with a M5.2. The M3.8 occurred Wednesday (March 18), just after noon. Like the bulk of the sequence so far, it had a strike-slip focal mechanism. Almost two hours earlier, there was a M3.1 at the same location. The M3.8 was also followed by a few aftershocks, up to M2.7 in magnitude. ------------------------------------------------------------ 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 ------------------------------------------------------------- 3/18 6:08 pm 36 4.5 117 37.3 2.2 18 mi. E of Coso Junction 3/18 7:11 pm 36 4.6 117 37.4 2.3 " 3/18 7:58 pm 36 5.6 117 51.1 2.1 6 mi. ENE of Coso Junction 3/18 9:05 pm 36 4.3 117 37.3 2.8 18 mi. E of Coso Junction 3/18 10:24 pm 35 15.6 118 33.4 2.1 10 mi. NW of Tehachapi 3/19 2:14 am 33 58.6 118 13.2 2.1 1 mi. NNW of South Gate 3/19 2:26 am 36 4.2 117 37.3 2.4 18 mi. E of Coso Junction 3/19 12:33 pm 34 30.1 116 30.7 2.2 26 mi. N of Yucca Valley 3/19 1:20 pm 36 4.7 117 37.0 2.4 18 mi. E of Coso Junction 3/19 8:32 pm 36 4.5 117 37.5 2.1 " 3/20 10:48 am 36 4.6 117 37.5 2.0 " 3/20 4:22 pm 34 58.2 116 49.1 2.1 12 mi. ENE of Barstow 3/20 4:55 pm 32 23.9 115 16.2 2.0 22 mi. SE of Calexico 3/21 1:19 am 36 5.0 117 37.0 2.1 18 mi. E of Coso Junction 3/21 6:20 am 36 4.2 117 37.3 2.3 " 3/21 8:32 am 36 4.3 117 37.8 2.0 17 mi. E of Coso Junction 3/21 12:02 pm 34 12.0 117 38.0 2.1 6 mi. S of Mt. Baldy 3/21 6:15 pm 36 4.9 117 36.9 2.5 18 mi. E of Coso Junction 3/21 6:21 pm 36 6.1 117 36.2 2.0 19 mi. ENE of Coso Junction 3/22 12:08 am 34 23.7 116 27.3 2.3 19 mi. N of Yucca Valley 3/22 3:05 am 36 4.3 117 38.2 2.1 17 mi. E of Coso Junction 3/22 4:16 pm 36 3.8 117 38.4 2.3 " 3/23 3:58 am 36 4.1 117 38.7 2.0 " 3/23 10:56 am 34 27.1 119 29.3 3.2 4 mi. NNE of Carpinteria 3/23 11:40 am 36 4.0 117 38.0 2.3 17 mi. E of Coso Junction 3/23 4:25 pm 36 4.2 117 36.9 2.2 18 mi. E of Coso Junction 3/23 8:43 pm 34 28.4 120 35.7 2.4 7 mi. SSE of Pt. Arguello 3/24 12:38 am 33 24.8 116 27.9 2.2 12 mi. NNW of Borrego Springs 3/24 12:38 am 33 25.5 116 27.6 2.2 " 3/24 3:48 am 36 4.5 117 37.2 2.3 18 mi. E of Coso Junction 3/24 3:51 am 34 35.3 117 14.8 2.3 4 mi. NE of Victorville 3/24 1:53 pm 35 12.8 118 7.0 3.0 11 mi. NNE of Mojave 3/24 6:35 pm 36 3.9 117 37.1 2.0 18 mi. E of Coso Junction 3/25 1:49 am 35 46.9 117 40.1 2.1 11 mi. N of Ridgecrest 3/25 4:55 am 36 52.9 116 34.7 2.9 33 mi. NNE of Furnace Creek 3/25 5:08 am 36 51.9 116 30.6 2.4 34 mi. NNE of Furnace Creek -------------------------------------------------------------