Magnitude 6.0 - CENTRAL CALIFORNIA
2004 September 28 17:15:24 UTC

Preliminary Earthquake Report
California Integrated Seismic Net
USGS/ Caltech/ CGS/ UCB/ UCSD/ UNR

This earthquake is the anticipated Parkfield earthquake, Mw 6.0 on the San Andreas fault. It ruptured roughly the same segment of the fault that broke in 1966. The earthquake occurred at 10:15 AM PDT on September 28, 2004. Its hypocenter was located at 35 degrees, 49 minutes north, 120 degrees 22 minutes west, at a depth of 8 km or 5 miles. From this point, about 7 miles SW of the town of Parkfield, it ruptured primarily northwest along the San Andreas fault. Strong shaking during this event lasted for about 10 seconds. This earthquake is the seventh in a series of repeating earthquakes on this stretch of the fault. The previous events were in 1857, 1881, 1901, 1922, 1934, and 1966.

Magnitude 6.0 Date-Time Tuesday, September 28, 2004 at 17:15:24 (UTC) = Coordinated Universal Time Tuesday, September 28, 2004 at 10:15:24 AM = local time at epicenter Location 35.815°N, 120.374°W Depth 7.9 km (4.9 miles) Region CENTRAL CALIFORNIA Distances 11 km (7 miles) SSE (151°) from Parkfield, CA 18 km (11 miles) N (1°) from Shandon, CA 30 km (18 miles) ENE (76°) from San Miguel, CA 34 km (21 miles) NE (53°) from Paso Robles, CA 217 km (135 miles) SE (141°) from San Jose City Hall, CA Location Uncertainty horizontal +/- 0.4 km (0.2 miles); depth +/- 0.6 km (0.4 miles) Parameters Nst=248, Nph=248, Dmin=3 km, Rmss=0.11 sec, Gp= 94°, M-type=regional moment magnitude (Mw), Version=7 Source California Integrated Seismic Net USGS/ Caltech/ CGS/ UCB/ UCSD/ UNR Event ID nc51147892

Tectonic Summary Aftershock Warning Waveforms for ShakeMap Waveforms (Dig and BB) Location Maps: NEIC Maps Topo map centered at earthquake (This link takes you offsite. Not all regions have topo maps available.) Did you feel it? Report shaking and damage at your location. You can also view a map displaying accumulated data from your report and others. ShakeMap shaking intensity maps Berkeley moment tensor solution Historical Moment Tensor Solutions Seismic Hazard Map Historical Seismicity Theoretical P-Wave Travel Times Earthquake Summary Map NCSN First Motion Mechanism 1 Earthquake Information for CALIFORNIA The Parkfield Earthquake Experiment Historic Earthquakes near Parkfield, California Archive of newsworthy events

News Links 6.0-magnitude earthquake rattled central California Researchers digest data from Calif. quake Earthquake shakes Central California Organizations CISN Special Earthquake Report Special earthquake report from IRIS California Geological Survey Special Earthquake Report

For more information, go to http://quake.wr.usgs.gov/ || Contacts

The official magnitude for this earthquake is indicated at the top of this page. This was the best available estimate of the earthquake's size, at the time that this page was created. Other magnitudes associated with web pages linked from here are those determined at various times following the earthquake with different types of seismic data. Although, given the data used, they are legitimate estimates of magnitude, they are not considered the official magnitude.

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