Event Name: Parkfield, California Earthquake
Event Date: 09/28/2004, 17:15 UTC (09/28/2004, 10:15 AM PDT)
Event Identification: 20040928_1715
Recorder Type: GEOS; Kinemetrics: Etna, K2; Reftek: RF130, RT72-04
Network Event ID#: nc51147892

Data Organization and Format ||  Download (updated 07/20/2005) ||  Tables (updated 07/20/2005) || Errata (updated 07/20/2005)

Data Organization and Format

The September 28, 2004, 17:15 UTC, Mw 6.0, Parkfield, California Earthquake data recorded by the USGS National Strong-Motion Network (NSMN),  USGS Northern California Seismic Network (NCSN), USGS General Earthquake Observation System (GEOS), and  USGS Parkfield Dense Seismograph Array (UPSAR) are available via the NSMP ftp server in the folder (directory) "20040928_1715" (https://ca.water.usgs.gov/nsmp/20040928_1715).    The time series provided are available in uncorrected acceleration, corrected acceleration, corrected velocity, corrected displacement, response spectra (relative displacement, relative velocity, pseudo-velocity, and absolute acceleration), and Fourier amplitude spectra of corrected acceleration.  All of the data are in SMC format.  

NSMN and NCSN data have the following file-naming conventions:

where 'RRRR' is the four-digit recorder serial number (including leading 0's) for the NSMN data and is the four-digit station code for the NCSN data, 'c' is the channel number of the recorder ('a' corresponds to channel 1, 'b' to channel 2 , etc), the '_x' is used to identify the data type, and the suffix refers to the data format (rs2 and fs1 are valid SMC format types recognized by the BAP processing program.  

GEOS file-naming conventions:

where 'PG' is "Parkfield GEOS" to distinguish them from non-GEOS data, '?' is the one-digit station code, 'FU' designates records from accelerometers, 'c' is the channel number of the recorder ('a' corresponds to channel 1, 'b' to channel 2 , etc), the '_x' is used to identify the data type, and the suffix refers to the data format (rs2 and fs1 are valid SMC format types recognized by the BAP processing program. In the future, station codes of the form PG?DD for GEOS recorders in the Parkfield Array will be used to designate records from dilatometers.

UPSAR data are posted using IRIS SNCL conventions:

where 'upsar' is "USGS Parkfield Dense Seismograph Array" to distinguish them from non-UPSAR data, 'np' is the two-character network code for "NSMP", 'hno' is the three-character channel code (h is a code indicating the passband and sampling rate of the instrument, n indicates an accelerometer, o is the sensor orientation), 'ss' is the two-character location code (UPSAR station number in this case), the '_x' is used to identify the data type, and the suffix refers to the data format (rs2 and fs1 are valid SMC format types recognized by the BAP processing program. 

The data are stored in two directories: uncorrected (only uncorrected acceleration) and corrected (all of the corrected and processed data, including acceleration, velocity, displacement, response spectra and Fourier amplitude spectra. This convention for organizing the data was implemented to avoid confusion between the directory names (Vol1, Vol2, … Vol6) previously used for some earlier events and the standard conventions for Volume1, Volume2 and Volume 3 processing.

Information on how the data are processed can be found in the section on DATA PROCESSING.  Note that these data were processed using an acausal Butterworth locut filter.

Downloads

• Data for station PHOB, Hog Canyon were added to the data set on 10/04/2004. Currently only acceleration and velocity time series records are being served for station PHOB. The displacement records derived from the unfiltered acceleration indicate that a small permanent offset may have occurred at this site due to the earthquake, and the records are being evaluated to verify this observation.
• Data for eleven GEOS recorders were added to the data set on 10/08/2004.  GEOS file names all begin with the string "pg" for "Parkfield GEOS" to distinguish them from non-GEOS data.
• Station codes for three of the GEOS recorders were revised and all data tables and files corrected on 10/13/2004 (see errata).
• Data for the USGS Parkfield Dense Seismograph Array (UPSAR) were added to data set on 5/23/2005.  UPSAR file names all begin with the string 'upsar' to distinguish them from non-UPSAR data.
• Sensor orientations for Parkfield GEOS station JFU (Joaquin Canyon) were corrected in the peaks table and time series files on 7/20/2005 (see errata)

Tables

List of corrected peak ground accelerations and velocities and pseudo-spectral accelerations for available time-series data, updated 07/20/2005 (to obtain list as Excel spreadsheet click here ; click cancel button if get pop-up window requesting user name and password)

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This page was posted on September 28, 2004; updated 07/20/2005.