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CMB - Columbia College, Columbia, CA, USA

Site of CMB vault

Site of CMB vault

1986/10/25 00:00:00 - Present

Latitude: 38.0345
Longitude: -120.3865
Elevation: 697.00 meters

STS-1 installation at CMB

STS-1 installation at CMB

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

Location:
Site is located on the campus of Columbia College in Sonora, California. This site was established to relocate instrumentation from the JAS1 in Jamestown.

CMB was upgraded with partial funding from the IRIS Consortium and data are archived at the IRIS Data Management Center as well as the NCEDC. CMB is also a cooperative station with the US National Seismic Network.

Geology:
Paleozoic marine limestone

Vault/Borehole conditions:
The vault is a buried fiberglass cylinder, eight feet in diameter and six feet deep. It has a flat top at grade level with a hatch for entry. The floor is concrete poured directly on rock. The datalogger and supporting equipment are located in an air conditioned trailer located about 70 feet from the vault and connected via underground conduits. The seismometers are thermally insulated with 4" of polyurethane foam and the top of the vault is covered with bark for additional insulation.

Instrumentation:
SensorDataloggerStart DateEnd DateSEED ChannelsLocation
Battery VoltageQ9352001/06/01PresentUE?,LE?
Guralp CMG-3 Extended BB H SeismometerDWSSN1989/03/171992/06/25LH?,BH?
Guralp CMG-3 Extended BB V SeismometerDWSSN1989/03/171992/06/25LH?,BH?
Internal TemperatureQ9352001/06/01PresentUK?
Kinemetrics FBA-23 Accel. (2 g max 1.25 v/g)Q9351992/06/25PresentHL?,BL?,LL?
Motorola MPX201 PressureQ9351998/03/05PresentLD?
Streckeisen STS-1 VBB Feedback SeismometerQ9351992/06/25PresentHH?,BH?,LH?,UH?,VH?
Streckeisen STS-1 VBB Feedback SeismometerQ9352001/06/01PresentUM?
Teledyde Geotech T210 LP V SeismometerDWSSN1986/10/251989/03/17LH?,BH?
Teledyne Geotech S13 SP V SeismometerDWSSN1986/10/251992/06/25SH?
Teledyne Geotech T200 LP H SeismometerDWSSN1986/10/251989/03/17BH?,LH?
YSI 44031 ThermistorQ9351998/03/05PresentLK?

The CMB site also is home to a continuously operating GPS receiver (CMBB) as part of the BARD network.

Network:
BK (Berkeley Digital Seismic Network)

Operation Notes: (may not be current)
This section summarizes major changes in equipment or in instrumentation at CMB.

  • 06/15/2004: BH channels sampling rate changed from 20 to 40 Hz.
  • 09/19/2000: The STS-1 NS was replaced.
  • 08/07/2000: The air conditioner in the trailer is reported to be failing. In addition, analysis of a recent deep teleseism has revealed a problem with the north component, where the amplitude appears to be too small by approximately a factor of 2. This problem seems to have appeared in August 1999.
  • 01/06/2000: New BARD GPS monument installed, with Ashtech receiver.
  • 12/11/1999: Q980 software upgraded to MSHEAR.
  • 05/13/1998: Installed barometer and thermometer set. Replaced GOES clock with GPS.
  • 03/04/1998: Q980 upgraded with 4 GB disk and ethernet board. Warpless baseplates installed.
  • 09/25/1996: Replaced FBA-23.
  • 01/22/1996: Analog telemetry replaced with frame-relay connection with a Vanguard 300 frad.
  • 12/09/1993: BARD GPS monument installed, with Ashtech receiver.
  • 06/24/1992: A Streckeisen STS-1 and a Kinemetrics FBA-23 were installed with a Quanterra Q980 datalogger, replacing the Guralp CMG-3 and DRS system. This upgrade was partially funded by IRIS and data from this site are contributed to the IRIS Data Management Center.
  • 03/17/1989: A set of CMG-3 seismometers with a DRS recording system were installed at this site. The station formed part of the DWWSSN and data from this site were contributed to the Global Seismic Network.

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