Seismo-Watch
    Earthquake Alert Bulletin No: 98-246
    Preliminary data indicates a significant earthquake has occurred:

    Regional Location:

    Preliminary Magnitude:

    Moment Magnitude:

    Greenwich Mean Date:
    Greenwich Mean Time:
    Latitude:
    Longitude:
    Focal Depth (km):
    Analysis Quality (A-D):

    CENTRAL CALIFORNIA

    4.0 ML (NCSN)

    3.8 Mw (UCBSL)

    98/10/09
    06:50:31
    36.96N
    121.57W
    6.5 km
    A
    Notations:
    An earthquake registering a preliminary magnitude of ML 4.0 (NCSN), Mw 4.0 (UCBSL) occurred at 06:50:31 UTC, October 9 (11:50 p.m. PDT, October 8), in the South San Francisco Bay Area, Northern California. The focal point was placed at the shallow depth of 6.5 km and the Moment magnitude analysis is from the University of California, Berkeley, Seismological Laboratory. The quake was centered about 12 miles northwest of Hollister or about 3 miles south of Gilroy in the Southern Santa Cruz Mountains on the Sargent fault. The focal mechanism indicated nearly pure strike-slip fault motion along a northwest trending fault plane. This solution agrees with the orientation and motion typical of the Sargent fault. The earthquake was widely felt in the South San Francisco Bay Area, waking some people who had just fallen to sleep. Seismo-Watch received a number of felt reports on their web site as well as on their 1-800-852-2960 message line. Dishware and windows rattled, hanging plants swung and tall buildings swayed, but there were no reports of items toppling from tables or shelves. The quake was centered not far from a similar magnitude event (M4.0) on June 15th earlier this year and a M5.4 earthquake occurred about 6 miles southeast of San Juan Bautista on August 12 (More Info on the San Juan Bautista M5.4 earthquake).
     
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    Subtract 7 hours to obtain PDT or 4 hours for EDT
    Location Quality: A (good), B (fair), C (poor), D (bad)
    Magnitude: Ml (local or Richter magnitude), Lg (mblg), Md (duration), Mb (body wave), Ms (surface wave), Mw (moment)
    Standard Sources Include:
    U.S. Geological Survey, National Earthquake Information Center, Golden, CO (NEIC)
    Harvard Geophysical Observatory, Harvard University, Cambridge, MA (HRV)
    U.S. Geological Survey, Northern California Seismic Network (NCSN)
    University of California, Berkeley, Seismological Laboratory (UCBSL)
    California Institute of Technology, Pasadena, California (Caltech)
    various wire reports and/or personal communications
    All data are preliminary and subject to change.
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