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125 Years of Sound Science, serving society

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

Station Name SAO (SAOB)
In Operation 1988/01/28 00:00:00 - Present
Elevation: 317.20 meters
Instrumentation Broadband

  • Site


    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.


    BK, BARD (Berkeley Digital Seismic Network and Bay Area Regional Deformation Network)


    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.

    GPS Monument Description

    Reinforced concrete monument
  • Plots & Figures

    Seismic Station Pictures

    View of SAO equipment building

    View of SAO equipment building

    View of SAO vault

    View of SAO vault

    GPS Station Timeseries

    Time series processing at the BSL

    Last year Clean Clean & detrended Raw Raw & detrended
    Lifetime Clean Clean & detrended Raw Raw & detrended
    Text file (final results only) Clean Raw

    GPS Station Pictures





  • Instrumentation

    Table of Seismic Instrumentation

    SensorDataloggerSEED ChannelsLocation
    BroadbandStreckeisen STS-1/E300 VBB Feedback SeismometerQ330HR-GFEBH?,HH?,LH?,VH?00
    AccelerometerKinemetrics FBA ES-T Accel. GFE (4 g max 5 v/g)Q330HR-GFEHN?00
    GPSTrimble NetRSAshtech Choke-RingSCIGN Tall-
    SensorDataloggerSEED ChannelsLocation
    OthersElectric Field Dipole (Pb-PbCl or Cu-CuS Anodes)Q4120BQ?,LQ?,UQ?,VQ?
    ElectroMagnetics Inc. BF4 MagnetometerQ4120BT?,LT?,UT?,VT?
    AuxiliaryBattery VoltageQ4120AE?
    Internal TemperatureQ4120AK?
  • Data & Metadata

    Waveforms and associated metadata, and GPS data, are available at the Northern California Earthquake Data Center (NCEDC).

    Waveform Data

    GPS Data

  • Data Quality

    Noise Analysis

    View more noise plots

    GPS Data Quality


    Data completeness is defined both as "Completeness of observations" and "Cycle slips per observation". "Completeness of Obs." is the number of epochs in the final RINEX file normalized to the expected number. This percentage will go down if time is missing from the RINEX file. "Cycle slips per Obs." is the total number of detected cycle slip normalized to the total number of observations in the RINEX file. This number will increase as the receiver loses lock on satellites more frequently.

    Previous Year
    SAOB completeness last year
    SAOB completeness lifetime


    The effects of multipath on the data are estimated by parameters for L1 and L2 (MP1 and MP2 respectively); see Estey and Meertens (GPS Solutions, 1999) for derivation. The daily value is the RMS of MP1 and MP2 throughout the day and for all satellites. Higher values indicate a greater prevalence and/or strength of multipathing, i.e. objects on the ground are providing multiple reflection pathways from the satellite to antenna.

    Previous Year
    SAOB multipath last year
    SAOB multipath lifetime