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SAO - San Andreas Geophysical Obs., Hollister, CA, USA |
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View of SAO equipment building |
1988/01/28 00:00:00 - Present
Latitude: 36.7640
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View of SAO vault |
Location |
Geology |
Vault Conditions
Instrumentation |
Network |
Operation Notes
Noise Characteristics |
Data Availability
- Location:
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Site is located at the San Andreas Geophysical Observatory
in the Hollister
Hills State Vehicle Recreation Area. The BSL first
occupied this site in 1966, with a variety of
geophysical instrumentation. The digital broadband sensors
were installed in 1988.
SAO is a cooperative station with the Advanced National Seismic System.
- Geology:
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Jurassic-Cretaceous Gabilan Granite
- Vault/Borehole conditions:
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The vault is a buried steel culvert liner with a set of three
isolation doors leading to the interior. The pier is poured concrete.
The datalogger and supporting equipment are located in an
air-conditioned structure approximately 50' away and connected via
underground conduits. The seismometers are thermally
insulated with 4" of polyurethane foam.
- Instrumentation:
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Sensor Datalogger Start Date End Date SEED Channels Location AntennaCurrent Q330HR-GFE 2010/05/20 Present VE? 00 ClockPhase Q330HR-GFE 2010/05/20 Present LC?,VC? 00 ClockQuality Q330HR-GFE 2010/05/20 Present LC?,VC? 00 InputVoltage Q330HR-GFE 2010/05/20 Present VE? 00 Kinemetrics FBA ES-T Accel. GFE (2 g max 10 v/g) Q330HR-GFE 2010/05/20 Present HN? 00 Streckeisen STS-1 VBB Feedback Seismometer Q330HR-GFE 2010/05/20 Present BH?,HH?,LH?,VH? 00 SystemCurrent Q330HR-GFE 2010/05/20 Present VE? 00 SystemTemperature Q330HR-GFE 2010/05/20 Present VK? 00 VCOValue Q330HR-GFE 2010/05/20 Present VC? 00 Battery Voltage Q4120 2010/05/20 Present AE? Electric Field Dipole (Pb-PbCl or Cu-CuS Anodes) Q4120 2002/03/30 Present BQ?,LQ?,UQ?,VQ? ElectroMagnetics Inc. BF4 Magnetometer Q4120 2002/03/09 Present BT?,LT?,UT?,VT? Internal Temperature Q4120 2010/05/20 Present AK? The SAO site also is home to a continuously operating GPS receiver (SAOB) as part of the BARD network. SAO is also the site of electro-magnetic observations.
- Network:
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BK (Berkeley Digital Seismic Network)
- Operation Notes: (may not be current)
- This section summarizes major changes in equipment or in instrumentation at SAO.
- 06/15/2004: Changed BH channels sampling rate to 40 Hz.
- 12/07/1999: Q980 upgraded with MSHEAR software.
- 06/04/1998: Replaced STS-1 Z sensor.
- 05/28/1998: Upgraded Q980 with 4 GB disk and ethernet card. Warpless baseplates installed.
- 04/02/1998: Replaced Q4120. Replaced Ashtech receiver.
- 08/21/1997: GPS antenna and Ashtech receiver installed.
- 02/17/1997: Q4120 replaced.
- 05/22/1996: Replaced FBA-23.
- 03/08/1996: Temperature/pressure package installed.
- 11/28/1995: Frame-relay telemetry installed.
- 08/15/1995: EM sensors installed.
- 04/07/1993: The Q980 unit was replaced. GPS clock installed.
- 03/02/1993: Installed NSN satellite system.
- 10/16/1992: Moved STS-1s onto a sand base, from the penny mounting.
- 06/10/1992: The 16-bit PC-based digitizer was replaced with a Quanterra Q980. A Kinemetrics FBA-23 was added.
- 05/23/1991: The STS-1 was upgraded from the BRB response to the VBB response.
- 01/28/1988: An STS-1 with a PC-based datalogger was installed.
- Noise Characteristics:
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The figures below are cumulative plots of power spectral density (psd)
determined from the broadband channels. In each figure, the vertical
component psd is plotted with blue diamonds, the north component
psd with red squares, and the east component psd with green circles.
The results are presented in the 5 different frequency bands, and
the USGS/Albuquerque low noise model is plotted as a dashed line in each.
The PSD units are in dB (decibel) relative to 1 (m/s**2)**2/Hz. The current
annual plot is updated weekly.
Cumulative PSD results 1999 2000 2001 2002 2003 2004 2005 
- Data Availability:
- BDSN waveforms and associated metadata are available at the
Northern California Earthquake Data Center (NCEDC).
- Map of BDSN stations
- Table of BDSN stations
- BK Information Directory, including
- List of station locations
- List of available channels
- Instrument Response
- Information on Quanterra Timing Errors
- Information on Quanterra 4120 FIR Filter changes - 6/30/2003
- Information on BH sampling rate change - 06/15/2004
- View digital seismograms
Several tools provide access to SEED format data at the NCEDC, both in terms of querying the archives and allowing data requests.- Querying the archives
- Requesting data by channel and time
- Requesting data by event
Help on using these tools is available.
