Hector Mines Bullion Wash Array

Processing Status

• 991129 - dumping data in 29 Palms
• 991205 - organizing raw data files, removing duplicated sections
• 991206 - creating segy files and logs from raw files
• 991207
  • organizing log files
  • combining separate logs from individual DASs for subsequent processing
  • organizing timing corrections
• 000906 - do event association to catalog
• 000908 - do improved event association to catalog, process data

Here are some notes about problems noticed in timing and response.

Station Locations

UCSB volunteers performed a differential GPS survey of most of the stations in the array. The reference station was a Marine training stake. The absolute location accuracy of this station is not know, but was probably originally done with a handheld GPS. The relative locations from this reference station should be accurate to less than a centimeter and could be made even more accurate with further processing. The RINEX files are available for post processing.

The Reftek's GPS systems provides us with these locations which are probably good to within 10 m of the external gps location.

This schematic view of the Bullion Wash Array shows the general layout of the array. The bottom section is a blow up of the dashed section in the top part.

Station Information

This Information Table summarizes many of the attributes of the sites including sensor types and gains.

This timeline summarizes the array status during deployment.

Event Association and Data

The following event associated data sets are preliminary releases of the data. Processing details are listed for each one. The archive names are generally in the format YYJJJHHMMSS.tar.gz where the YYJJJHHMMSS represents the UTC timestamp of the earthquake occurance time. For the sac files, a lower case channel (n,s or u) indicates a velocity transducer. upper case channels (S,D or W) represent acceleration data.

• 000906_prelim (This set is not online anymore)
  This set consistes of segy files that have had the following steps performed.
  • basic timing corrections
  • event association to a caltech catalog
• 000908_prelim (This set is not online anymore)
  This set consists of sac files that have had the following steps performed:
  • basic timing corrections
  • event association to a caltech catalog
  • timestamp and component based filenames mapped to station and orientation based filenames
  • scaling error corrections
  • converted to sac format
  • station locations inserted into headers
  • polarity corrections to velocity components
  • response corrections to velocity components
  • orientation corrections to velocity components (oriented n-s, e-w and u-d).
  • gtar format archives created using timestamp as name
• 001211_prelim download directory
  We decided to not actually execute the sac macros created to correct response and orientation. This allows the researcher to inspect the raw data files before working on the data.
  This set consists of sac files that have had the following steps performed:
  • basic timing corrections
  • event association to an updated caltech catalog (current as of 2000/12/11)
  • timestamp and component based filenames mapped to station and orientation based filenames
  • scaling error corrections
  • converted to sac format
  • station locations inserted into headers
  • earthquake locations inserted into headers
  • polarity corrections to velocity components
  • sac macros for response corrections to velocity components created (but not run).
  • sac macros for orientation corrections to velocity components (oriented n-s, e-w and u-d) created (but not run).
  • gtar format archives created using timestamp as name
  • event archives are all available from main directory or catalogued by number of stations associated in for that event.
  • some very simple documentation in each archive.
    • A README file giving some general info about the processing and the URL listing to this page.
    • An ERRORS file if there were some processing errors.
    • Possibly a STATUS file, containing information about the processing of the event.
  Problems/Issues still to be addressed:
  • several stations have timing problems that are not covered under the basic timing corrections.
  • the processing stream is all completely automated. So there has been only spot checks on the data to this point.
  • corrections to acceleration data needs to be included.
• Jamie spotted some errors in the database used to process the first few rounds of data. The problems were errors in the first line of the stations list and db.das files for station BWA00E00S. They have not been corrected yet (as of 08/15/01).
• The L4 at BWA00E00S has some problems (noticed when converting into real units back before AGU 2000).

We were hoping to have a cdrom created by the 1 year anniversary of the earthquake to distribute. We haven't quite gotten to that stage yet, but we expect to complete that soon. The cd will contain corrected data recorded on many stations. We appreciate any feedback that you can provide about the data quality and any problems that you may encounter. Contact: