Seismo-Watch
    Earthquake Alert Bulletin No: 98-239
    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):

    SOUTHERN CALIFORNIA

    Ml 4.7 (SCSN)

    Mw 4.1 (Caltech)

    98/10/01
    18:18:15
    34.12N
    116.92W
    6.7 km
    A
    Notations:
    An earthquake registering a preliminary magnitude of ML 4.7 (SCSN), Mw 4.1 (Caltech) occurred at 18:18:15 UTC (11:18 a.m. PDT), October 1, in Southern California. The focal point was placed at a depth of 6.7 km below the surface. The quake was centered in the San Bernardino Mountains about 6 miles west of Mt. San Gorgonio or about 21 miles east of San Bernardino, near Mountain Home Village. The quake triggered about 3 miles north of the main trace of the San Andreas fault and beneath the San Bernardino Mountains. The Caltech focal mechanism indicated strike-slip motion along a northwest-trending fault plane with a slight dip-slip component. This analysis agrees with the orientation of the San Andreas fault yet the quake occurred along a separate but parallel structure. The quake was sharply felt in the Inland Empire region and as far away as Los Angeles and San Diego. Seismo-Watch received several Felt Reports from people throughout the region and we are grateful for their observations. Although there have been no reports of damage or injury at this time, this quake was large enough to cause items to topple from tables and shelves. It was centered very close to a M4.8 temblor that triggered on August 12. There have a few aftershocks - the largest of which measured M2.4.
     
    Subscribe to the Seismo-Watch Earthquake Alert Bulletins
     
    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)
    Sources Include:
    U.S. Geological Survey, National Earthquake Information Center, Golden, CO (NEIC)
    Harvard Geophysical Observatory, Harvard University, Cambridge, MA (HRV)
    International Data Center, Center for Monitoring Research, Arlington, VA (IDC)
    California Institute of Technology, Pasadena, California (Caltech)
    various wire reports and/or personal communications
    All data are preliminary and subject to change.
    Copyright © 1998 Advanced Geologic Exploration
    Voice: 702-852-0992 / Fax: 702-852-3226
    Web Site: http://www.seismo-watch.com
    Re-transmission prohibited. All rights reserved.