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SAO - San Andreas Geophysical Obs., Hollister, CA, USA

View of SAO equipment building

View of SAO equipment building

1988/01/28 00:00:00 - Present

Latitude: 36.7640
Longitude: -121.4472
Elevation: 317.20 meters

View of SAO vault

View of SAO vault

Location | Geology | Vault Conditions
Instrumentation | Network | Operation Notes
Noise Characteristics | Data Availability

Location:
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 US National Seismic Network

Geology:
Jurassic-Cretaceous Gabilan Granite

Vault/Borehole conditions:
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:
SensorDataloggerStart DateEnd DateSEED ChannelsLocation
Battery VoltageQ41202003/01/09PresentAE?
Battery VoltageQ9352001/06/01PresentLE?,UE?
Electric Field Dipole (Pb-PbCl or Cu-CuS Anodes)Q41201996/02/23PresentVQ?,LQ?,BQ?,UQ?
ElectroMagnetics Inc. BF4 MagnetometerQ41201995/08/15PresentBT?,UT?,VT?,LT?
Internal TemperatureQ41202003/01/09PresentAK?
Internal TemperatureQ9352001/06/01PresentUK?
Kinemetrics FBA-23 Accel. (2 g max 1.25 v/g)Q9351992/06/11PresentLL?,BL?,HL?
Motorola MPX201 PressureQ9351996/03/07PresentLD?
Streckeisen STS-1 VBB Feedback SeismometerQ9351988/01/28PresentBH?,LH?
Streckeisen STS-1 VBB Feedback SeismometerQ9351992/06/11PresentUH?,HH?,VH?
Streckeisen STS-1 VBB Feedback SeismometerQ9352001/06/01PresentUM?
YSI 44031 ThermistorQ9351996/03/07PresentLK?

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:
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:
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
1999 PSD 2000 PSD 2001 PSD 2002 PSD 2003 PSD 2004 PSD 2005 PSD

Data Availability:
BDSN waveforms and associated metadata are available at the Northern California Earthquake Data Center (NCEDC).

Several tools provide access to SEED format data at the NCEDC, both in terms of querying the archives and allowing data requests.

Help on using these tools is available.

BDSN Overview | Map | Table



Berkeley Seismological Lab
215 McCone Hall, UC Berkeley
Berkeley CA 94720-4760
www@seismo.berkeley.edu

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Last modified: Wed Jun 25 13:34:08 PDT 2008