A magnitude 6.0 earthquake occurred near the central California town of Parkfield
Tuesday morning September 28. The Office of Emergency Services (OES) is reporting that there is no
significant damage and no casualties as a result of this earthquake. A series of aftershocks were felt,
the largest recorded was a preliminary M5.0 that occurred four minutes after the main shock.
Parkfield, which is located along the San Andreas fault zone, is well-known in
the scientific community. Geologists and seismologists from government agencies and universities
have been monitoring this rural area for earthquakes since the late 1970's. In 1985 the
Parkfield Earthquake Experiment
was launched by the U.S. Geological Survey and the State of California to
better understand what happens on a fault before, during and after an earthquake. The project has
involved more than 100 researchers from government agencies and universities.
Scientists from the California Geological Survey are en route to investigate
geologic features in the affected area and assist local agencies if requested. CGS geologists
will document any occurrences of ground failure such as fault rupture, liquefaction,
and/or landslides. This information will be incorporated to our earthquake hazard mapping programs.
Please return to our website over the next couple days and weeks and we will try to provide
pictures and commentary from field work related to this earthquake.
Summary of Surface Fault Rupture Mapping
DOC News Release of October 13, 2004 - Early Data Assessment
Shake Map of the Parkfield Earthquake
USGS Poster of the Parkfield Earthquake
Strong-Motion Data from the M6.0 Parkfield Earthquake
Other Agencies' Information about the
More historical Parkfield information
can be found in: Toppozada, T. R.,
D. M. Branum, M. S. Reichle, and C. L.
Hallstrom (2002) San Andreas Fault Zone,
California: M>=5.5 Earthquake History,
Bulletin of the Seismological Society of
America, Vol. 92, No. 7, pp 2555-2601.