Access to HRSN data
Operation of the HRSN can be divided into three stages:
- 1987-1998: Original HRSN data acquisition
- 1998-2000: PASSCAL RefTek recorders
- 2001-present: Q730 dataloggers and expansion to 13 stations
Availability and access to the data depend on the time period of interest. For more information on the network, see the HRSN overview.
- 1987-1998
-
The HRSN background describes the goals and design of the network and outlines the characteristics of the earthquake data set for the 1987-1998 time period. We strongly suggest that you read this document before using any of the HRSN earthquake data.
Location catalog
A catalog of earthquake locations derived from the HRSN data is available:
Each catalog line contains:
- Date and time (which may be incorrect -- see the HRSN overview for details).
- Hypocenter (location and depth in km)
- Number of observations used to compute the hypocenter
- RMS of location (in sec)
- ID number
The NCEDC has added the following fields to the catalog:
-
Normalized File Date
The normalized time of the date used in the filename of the waveform file. Some the times used in the waveform filenames are not normalized, eg hour >= 24, minute >= 60, etc. NO MATCH mean that no apparent waveform file could be matched to the earthquake based on the apparent time of the earthquake and the time in the filenames of the available waveform files. -
Waveform Filename
The best estimate as to which waveform file contains the waveform for the the event. NO MATCH mean that no apparent waveform file could be matched to the earthquake based on the time of the earthquake and the time in the waveform filenames.
Waveform Archive
The waveform file archive is available via research accounts at the NCEDC. The NCEDC currently has waveforms from January 1987 through June 1998.
The waveform files are stored in UC Berkeley/LBL SEGY format. UC Berkeley/LBL SEGY files contain both the printable and binary SEGY reel headers and one or more SEGY data traces. Each data trace consists of a SEGY trace header followed by trace data in binary 16 bit integer format in big-endian byte order.
Several programs are available to read the HRSN SEGY data files:
- bp2ms - will convert a HRSN data file to individual MiniSEED files, one per channel. The HRSN SEGY channels to SEED station and channel mapping is provided automatically by the script
- segy2ms - is a program used by the script bp2ms to perform the data conversion from UCB/LBL SEGY format MiniSEED format.
Once the files have been converted to MiniSEED, additional programs may be used to provide the data in either AH or SAC format
- ms2ah - converts a MiniSEED file to a Lamont AH (xdr) format data file.
- ms2sac - converts a MiniSEED file to SAC format. The coordinates for the stations will NOT be entered into the SAC header.
Pick Files
Many of the SEGY files also have pick files (files with a suffix of .pf.) The pick files for an event are located in the same directory as the waveform file for that event. The format of the pick files will be documented in the near future.
- 1998-2000
-
In the fall of 1998, the original HRSN acquisition system was replaced by
10 PASSCAL RefTek systems with continuous recording. In July of 1999, 6
of these recording systems were return to IRIS and 4 were left at critical
sites.
These recordings are not currently available at the NCEDC. It is hoped that these data will be available soon.
It is expected that the quality will be less than for the previous, centrally recorded data. However, the necessity of scanning the data for events has had a positive result - there are approximately four times the number of usable events (~ 4/day) than previously captured with the triggered system.
- 2001 - present
-
In the fall of 2000, the HRSN was upgraded with Q730 dataloggers.
In addition, 3 new borehole stations were constructed to provide
coverage for the San Andreas Fault
Observatory at Depth (SAFOD) drilling target.
One of the 3 sites was drilled in the fall of 2000 and the other 2 were
completed in the spring of 2001.
Continuous data from each site are transmitted to a central location for event detection. The DP data streams are used for local events, while the BP data streams will be used for regional and teleseismic events. The Parkfield central site provides approximately 1 month of local storage for the continuous data streams in order to facilitate event retrieval. At this time, telemetry limitations do not permit real-time transmission of all continuous data to the BSL; however, event data are transmitted to the BSL daily.
Significant efforts were made to identify and reduce noise sources arising from the new recording, telemetry and site design. The most significant contributors to noise have been identified and fixes have been developed and implemented at the 6 critical stations surrounding the SAFOD drilling target. Fixes for the remaining 7 stations, (some requiring the purchase of additional equipment) is currently underway. Identification and development of fixes for the lesser noise sources is continuing.
Waveform archive:
Currently, continuous data from the HRSN are being shipped to the NCEDC by tape and archived. This archive begins on 3/13/2001 (day 72) and the data are accessible using the SEED waveform query.
HRSN events are created through a central-site triggering algorithm. The HRSN events also include waveform data collected through the PASSCAL broadband array deployed in Parkfield. At present, the event data are only available through anonymous ftp, in a somewhat adhoc form. Please read README.HRSN. The data may be accessed here.
In the longer term, the HRSN event data will be available through the NCEDC Waveform Request interface when a mechanism for reviewing the events and constructing a catalog are in place.
|
Northern California Earthquake Data Center
|
|
Copyright 1995-2005, The Regents of the University of California.
Last modified: Mon Dec 17 17:31:07 PST 2007