Northern California
Seismic Network
Station Information | Data access | Collaborations
Since 1967 the U.S. Geological Survey has operated the Northern California Seismic Network (NCSN) to provide earthquake data for a wide range of research topics and hazard-reduction activities. The NCSN is designed to detect all local earthquakes having signal strength above the background level of microseisms. The network configuration was motivated by the need to monitor active faults and volcanoes with a station density sufficient to determine the focal depth of shallow (0-15 km) crustal earthquakes. Depending on the concentration of stations in a region, the magnitude (M) level at which earthquake detection is complete varies from approximately 1.4 in parts of the central Coast Ranges to 2.6 in the Klamath Mountain range. However, earthquakes with M<1.0 are routinely detected throughout the network.
The NCSN operates 412 stations in northern and central California and records an additional 100 stations maintained by 4 other institutions. It records a total of 924 channels of data using a mix of digital and analog systems. Nearly one fourth of the stations in the network are now digital, and 11 of the digital stations have broadband sensors, 92 have strong-motion sensors, and 11 are borehole installations. The remainder of the stations are mostly comprised of short-period vertical-component sensors. The NCSN telemetry system utlizes local collection nodes which are linked to Menlo Park via analog microwave, digital satellite telemetry, and leased digital circuits. The network also utilizes direct radio telemetry to Menlo Park and operates an extensive LAN that links urban stations located in the San Francisco Bay region.
NCSN network geometry is illustrated in this map of northern and central California.
- Network Code
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NC (also includes the Southern Hayward Fault Network)
- Typical Station Equipment
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NCSN stations generally fall into 4 categories: short-period analog, broadband,
strong-motion, and borehole. Each station type has its own equipment.
Short-period analog stations of the NCSN
- Vertical-component velocity sensor (Mark Products L-4)
- Central site digitization and timing
- Continuous telemetry to the USGS Menlo Park
- Backup power supply
Strong-motion stations of the NCSN
- 3-component accelerometer (Kinemetrics FBA-23 or EpiSensor)
- Vertical-component velocity sensor (Mark Products L-4)
- 24-bit Kinemetrics K2 or 16-bit DST digital data logger
- GPS clock
- Continuous telemetry to the USGS Menlo Park
- Backup power supply
Broadband stations of the NCSN
- 3-component broadband seismometer (Guralp 40T)
- 3-component accelerometer (Kinemetrics FBA-23 or EpiSensor)
- 24-bit Nanometrics HRD-24 data logger
- GPS clock
- Continuous telemetry to the USGS Menlo Park
- Backup power supply
Borehole stations of the NCSN
- 3-component geophone seismometer (Oyo HS1)
- 3-component accelerometer (Wilcoxon)
- 24-bit Nanometrics HRD24 data logger
- GPS clock
- Continuous telemetry to the USGS Menlo Park
- Backup power supply
- Typical Recorded Channels
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Sensor SEED Channels Rate (samples/sec) Sampling Mode FIR Filter Broadband seismometer HHZ, HHN, HHE 50.0 or 100.0 Continuous Causal Accelerometer HLZ, HLN, HLE
HNZ, HNN, HNE50.0 or 100.0 Continuous Causal Short-period seismometers EHZ, EHN, EHE
(VHZ, VHN, VHE)100.0 Continuous Causal - Station and Channel Information
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- Map of NCSN stations
- NC Information Directory, including
- List of station locations
- List of available channels
- Instrument Response
- Older sources of information on NCSN stations
- View seismograms from the NCSN
- Reports on the NCSN
- Northern California Seismic Network Bulletin, January - December 1992
- Reports on CREST
- Proceedings from the U.S. National Tsunami Hazard Mitigation Program Review and International Tsunami Symposium, Seattle, Washington 7-10 August 2001
- Reports on ANSS upgrades
- Data Access
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An earthquake catalog is produced from analysis of the NCSN data.
Locations, magnitude, phases, coda durations, and first-motion mechanisms
are available using the
earthquake catalog search.
As of 11/11/2004, NCSN waveform data are available in SEED as well as its original CUSP format. As a result, the NCSN data may be accessed using SEED-format tools as well as through the EVT_FAST waveform request form. 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
Help on using these tools is available.
Although the NCSN is primarily directed toward local earthquakes, recordings of some regional and teleseismic events are available from the NCEDC. A list of events and the status of the data is here:
- Collaborations
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The NCSN records and exchanges seismic data with several other institutions.
- California Institute of Technology Seismological Laboratory
- California Department of Water Resources
- Lawrence Livermore National Laboratory
- NOAA Pacific Tsunami Warning Center
- NOAA West Coast and Alaska Tsunami Warning Center
- USGS National Seismic Network
- USGS National Strong Motion Program
- University of California Berkeley Seismological Laboratory
- University of Nevada Reno Seismological Laboratory
- University of Washington Pacific Northwest Seismic Network
- More information
- If you have additional questions on the Northern California Seismic Network, you may contact oppen@usgs.gov.
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Northern California Earthquake Data Center
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Copyright 1995-2005, The Regents of the University of California.
Last modified: Mon Dec 17 17:31:07 PST 2007