CMB - Columbia College, Columbia, CA, USA

We operate broadband and borehole stations under the network code BK. The Berkeley Digital Seismic Network (BDSN) is a regional network of very broadband and strong motion seismic stations designed to monitor regional seismic activity as well as provide high quality data. The Berkeley borehole stations have borehole geophones or other seismic sensors and may have other geophysical instrumentation.

BARD is our GPS network for monitoring crustal deformation across the Pacific-North America plate boundary and in the San Francisco Bay Area for earthquake hazard reduction studies and rapid earthquake emergency response assessment

Station Name CMB (CMBB)
In Operation 1986/10/25 00:00:00 - Present
Elevation: 697.0 meters
Instrumentation Broadband


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 Advanced National Seismic System.


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


Paleozoic marine limestone

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.

GPS Monument Description

Poured concrete cylinder with steel reinforcement

Seismic Station Pictures

Site of CMB vault

Site of CMB vault

STS-1 installation at CMB

STS-1 installation at CMB

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





Table of Seismic Instrumentation

SensorDataloggerSEED ChannelsLocation
BroadbandStreckeisen STS-1/E300 VBB Feedback Horizontal SeismometerQ330HR-GFEBH?,HH?,LH?,VH?00
Streckeisen STS-1/E300 VBB Feedback Vertical SeismometerQ330HR-GFEBH?,HH?,LH?,VH?00
AccelerometerKinemetrics FBA ES-T Accel. GFE (4 g max 5 v/g)Q330HR-GFEHN?00
Setra Systems Model 270 BarometerQ330HR-GFELD?EP

GPS Instrumentation

GPSSeptentrio PolaRx5Ashtech Choke-RingSCIGN Tall-

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

Waveform Data

GPS Data

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
CMBB completeness last year
CMBB 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
CMBB multipath last year
CMBB multipath lifetime

Signal-to-Noise Ratio

The Signal-to-Noise ratios are the mean values above the QC elevation mask for L1 and L2 respectively.

Previous Year
CMBB SNR last year
CMBB SNR lifetime