Regional Location:

    Preliminary Magnitude:

    Greenwich Mean Date:
    Greenwich Mean Time:
    Latitude:
    Longitude:
    Focal Depth:

    		 COSO VOLCANIC FIELD, EAST-CENTRAL CALIF.

    4.0 (SCSN) 4.0 (UNRSL)

    01/07/14
    17:20:28 (10:30 a.m. local time)
    36.027N
    117.886W
    0.2 km (at or near-surface)
    Seismo-Watch Significant Earthquake Reports- No. 01-024
    More Special Earthquake Reports
    COSO JUNCTION, CALIFORNIA, July 14, 2001 (Seismo-Watch) -- Preliminary data indicates that an earthquake measuring M4.0 (SCSN), M4.0 (UNRSL) occurred at 17:30:28 UTC (10:30 a.m. local time), July 14 about 77 miles northeast of Bakersfield, 31 miles north of Ridgecrest along the eastern side of the Sierra near Coso Junction. It was quickly followed by another tremor nearly as large and a robust aftershock sequence which is ongoing. No damage or injuries have been reported.
    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 western margin of the Coso Volcanic Field and within the Rose Valley fault zone.

    Foreshocks and aftershocks
    A few     M1s and M2s triggered earlier that morning, but the Coso area is one of the most active in the United States and action like this would not be uncommon.

    A 10:33 and not more than 2-1/2 minutes after the main jolt was a M3.9 temblor. A robust aftershock sequence followed, and in the subsequent hour was clicking along at about 18 quakes per hour. One additional quake measuring in the M3 range occurred at 10:55 a.m. and measured M3.4.

    Felt Reports
    The temblor was felt by several people in the region. Although Seismo-Watch has not received any direct reports, the USGS has received a few notifications from as far away as Isabella and Ridgecrest. It is not likely the temblor was strong enough to topple items from tables or shelves.

    Brief Background
    The Coso Volcanic Field is one of the most seismically active regions in the United States, producing dozens of tremors in the     M1 and M2 range each week. Tremors in the M3 range occur at a rate of 2-6 per month and M4 action happens couple-three times each year. The last M4 temblor occurred March 28, 2000 and measured M4.3. The most recent activity in the M5 range happened in 1996 and 1998 when tremors of M5.3 and M5.1, and M5.2 and M5.0, respectively, occurred with a day of each other. These tremors were actually recorded along the eastern side of the Coso Volcanic Field, some 15 miles from today's action.

    Earthquake swarms are common in the Coso area, often producing hundreds of tremors over short periods of time, like a few days. This kind of brisk and robust seismically is common in volcanic areas, such as Long Valley Caldera located near Mammoth Lakes, and Yellowstone Caldera at Yellowstone. The Coso Volcanic Field shows stunning examples of volcanic activity, probably last active 30-40,000 years ago, but ash emission and small cone building episodes may be Holocene (>10,000 years) in age.

    The known geothermal resource area (KGRA) has been commercially mined for geothermal energy since the 1980s.

    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: 1:20 p.m., July 14, 2001
    EQ Flash! Earthquake Alert Bulletins!

    The fastest way to stay informed of current earthquake activity anywhere on the planet.

    E-mail • Pagers • Fax • Cell Phones • PDAs

    Its FREE!!

    Order your service NOW!

    Seismo-Watch, Inc.
    P.O. Box 18012 , Reno, NV 89511-8012
    Toll Free 24 hour Message Line 1-800-852-2960
    Office: 775-852-0992 / Fax: 775-852-3226
    e-mail: info@seismo-watch.com