Data from the Parkfield mainshock as recorded by the string in the
SAFOD Pilot Hole. The data were recorded at 500 samples/sec on the Geores
recording system at SAFOD. The sensors are 15 Hz 3-component geophones. The
information below is also provided in this file
SAFOD_3com_instruments.txt gives the original
channel assignments, level names (Pods) and depths below the ground surface in feet.
Because of the intersection of the main hole into the pilot hole, only pods 26 through
32 are operational. They appear in positions 10 through 30 in the multiplexed data
files. The order of components is z, h1, h2 at each level. (S26 z is in column 10,
S26 h1 is in column 11, ... , S32 h2 is in column 30).
Pilot_Hole_Sonde_Positions.txt contains
coordinate and orientation information for each level. This information was developed by Volker Oye
as part of his theis work at NORSAR. A manuscript "Orientation of three-component geophones in the San
Andreas Fault Observatory at Depth Pilot Hole, Parkfield, California" by Volker Oye and
William L. Ellsworth has been submitted to BSSA.
There are 8 data files each with 65.532 seconds of data (32768 data points). The earliest
file, 0987, is immediately before the main shock. File 0988 contains the main shock. Note
that there is a small gap between consecutive files of 30-35 msec. Data in the gap were not
recorded and are lost.
Recordings on the vertical component remain onscale through the earthquake. The horizontal
componets clip for a few cycles. From the appearance of the data, the clipped peaks are about
a factor of 2 above the clipping level.
The data are given in two formats. ASCII flat files (30 columns by 32768 rows) appear in the
*.txt files. SEG-2 files are in the *.dat files.
The data in the files are the milivolts output of the instruments
Instrument details:
- Sensors:GeoSpace GS-20DM
- Natural Frequency:15 Hz
- DC resistance:2400 Ohms
- Intristic Voltage Sensitivity:2.64 V/in./sec, 1.040 V/cm/sec (Whole system; see comment below *)
- Damping:0.57
- Moving Mass7.8 gr
*Two sensors are connected in series so the Voltage Sensitivity
is twice the single instrument output of 1.32 V/in./sec