Preliminary analysis of strong-motion recordings from the 28 September 2004 Parkfield, California earthquake

The 2004 M_w 6.0 Parkfield earthquake of 28 September 2004 occurred on the San Andreas Fault near the small town of Parkfield in central California. As a result of a widely accepted likelihood of an earthquake in the area, a large number of strong-motion stations and other types of seismic stations had been deployed in the area.

The Parkfield earthquake occurred along the same segment of the San Andreas Fault that ruptured during the 1966 Parkfield earthquake, resulting in a unique set of strong-motion measurements by arrays designed specifically for the purpose of recording an event along this fault segment. The most extensive and dense set of near-fault strong-motion recordings yet obtained for any earthquake in California was obtained in this event. This paper provides a detailed description of the arrays and the resultant strong-motion measurements of the mainshock, as well as preliminary observations. We also invite interested parties to participate in the Turkey Flat blind prediction experiment, described later in the paper. More general preliminary seismological results for this earthquake can be found in Langbein et al. (2005, this issue).