Regional Location: Preliminary Magnitude: Greenwich Mean Date: Greenwich Mean Time: Latitude: Longitude: Focal Depth:		COSO VOLCANIC FIELD, EAST-CENTRAL CALIF. ML 4.9 (SCSN) Mw 5.2 (UCBSL) 01/07/17 12:07:25 (5:07 a.m. local time) 36.017N 117.887W 4.1 km (at or near-surface)
		Seismo-Watch Significant Earthquake Reports- No. 01-025
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		COSO JUNCTION, CALIFORNIA, July 17, 2001 (Seismo-Watch) -- The Coso earthquake swarm, which began with a M4.0 earthquake on July 14, intensified this morning, producing a number of sizable tremors including one registering ML 4.9 (SCSN), Mw 5.2 (UCBSL), Mw 5.2 (Harvard) that occurred at 12:07:25 UTC (05:07 a.m. local time), July 17. It was centered about 77 miles northeast of Bakersfield, 31 miles north of Ridgecrest and 20 miles south of Olancha along the eastern side of the Sierra, near Coso Junction. Seismo-Watch EQ Flash! Alert Bulletins subscribers received a notification of the earthquake within minutes of the shaking. You should subscribe to the service too! It's FREE and Fast! NOW!! Wireless EQ Flash! via pager, cell phone or PDA's! More info. A preliminary location places the quake about four miles east-southeast of Coso Junction in upper Rose Valley, and just outside the northwestern boundary to the China Lake Naval Weapons Center. See a Topo Zone location map. This is along the southwestern margin of the Coso Volcanic Field and within the Rose Valley fault zone, and essentially in the same location as the M4.0 on Saturday, July 14. Analysis by U.C. Berkeley Seismological Laboratory determined that earthquake was caused by strike-slip (side to side) motion along a nearly north-south trending fault, which is the same orientation of the Rose Valley fault zone. See fault plane solution here. Harvard Geophysical Laboratory also produced a similar result, yet their analysis showed a very slight oblique component. (See Harvard's solution) Aftershocks The main shock was followed by a robust aftershock sequence which has included dozens of tremors, including nine M3s and two M4s, a M4.7 at 5:25 a.m. and a M4.7 at 6:00 a.m. For a complete list of current aftershocks, please see the USGS recent earthquakes page (Note: the information on this page is only for a current seven day window) See a list of M4.0 quakes in the China Lake Basin-Coso area from 1932 - 2000. Felt Earthquake Reports The main M5.2 jolt woke thousands of people from sleep and was felt as far away as Bakersfield and Las Vegas, Nevada. There have been no reports of damage or injuries at this time, but a quake of this magnitude is capable of knocking items from tables and shelves, pictures from walls and frightening residents within 10-20 miles of the epicenter. Many people reported feeling the two larger aftershocks as well. Background Information For background information, please see the earlier report for the July 14 Coso M4.0 earthquake. More information will be provided as soon as possible and this page will automatically refresh every 90 seconds to give you the latest news. Here are some links about the Coso Volcanic Area: USGS Description Global Volcanism Program Volcanism along the eastern Sierra Nevada Frontal Scarp Geologic Map of the Coso Area Mapping and Geologic Interpretation of the Coso Geothermal Area Coso Hot Springs Additional Seismic information links: Seismo-Watch Links to California Activity USGS Recent Earthquakes Page USGS Community Intensity Report Nevada Broadcast of Earthquakes, UNRSL Seismograms of the earthquake series from nearby stations: East Mammoth Pilot Ridge Mainstream media news reports: None at this time Report update: 10:50 a.m., July 17, 2001
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