link to main US Geological Survey website
125 Years of Science for America - 1879 to 2004
U.S. Geological Survey
Open-File Report 2004-1376
Version 1.0

Acceleration and Volumetric Strain Generated by the Parkfield 2004 Earthquake on the GEOS Strong-Motion Array Near Parkfield, Calif.

By Roger D. Borcherdt, Malcolm J.S. Johnston, Christopher Dietel, Gary Glassmoyer, Doug Myren, and Christopher Stephens


index map showing Parkfield and 25 miles either side
Map showing location of accelerometers (A), velocity transducers (V), dilatometers (D) and GEOS recorders that provided on-scale recordings of the motions generated by the Parkfield earthquake of September 28, 2004.

An integrated array of 11 General Earthquake Observation System (GEOS) stations installed near Parkfield, Calif. provided on scale broad-band, wide-dynamic measurements of acceleration and volumetric strain of the Parkfield earthquake (M 6.0) of September 28, 2004. Three component measurements of acceleration were obtained at each of the stations. Measurements of collocated acceleration and volumetric strain were obtained at four of the stations. Measurements of velocity at most sites were on scale only for the initial P-wave arrival. When considered in the context of the extensive set of strong-motion recordings obtained on more than 40 analog stations by the California Strong-Motion Instrumentation Program and those on the dense array of Spudich, et al, (1988), these recordings provide an unprecedented document of the nature of the near source strong motion generated by a M 6.0 earthquake. The data set reported herein provides the most extensive set of near field broad band wide dynamic range measurements of acceleration and volumetric strain for an earthquake as large as M 6 of which the authors are aware. As a result considerable interest has been expressed in these data. This report is intended to describe the data and facilitate its use to resolve a number of scientific and engineering questions concerning earthquake rupture processes and resultant near field motions and strains. This report provides a description of the array, its scientific objectives and the strong-motion recordings obtained of the main shock. The report provides copies of the uncorrected and corrected data. Copies of the inferred velocities, displacements, and Psuedo velocity response spectra are provided. Digital versions of these recordings are accessible with information available through the internet at several locations given in the report below.

Download this report as a 75-page PDF document (of2004-1376.pdf; 4.9 MB)

For questions about the content of this report, contact Roger Borcherdt

Version history

Download a current version of Acrobat Reader for free

| Help | PDF help | Publications main page | Open-File Reports for 2004 |
| Privacy Statement | Disclaimer | Accessibility |
| Geologic Division | Earthquake Hazards Program |
This report is available only on the Web

| Department of the Interior | U.S. Geological Survey |
URL of this page:
Maintained by: Michael Diggles
Date created: October 28, 2004
Date last modified: October 29, 2004 (mfd)