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Northern California Earthquake Data Center



Starting 2015/10/07, the Northern California Seismic System (NCSS) is reporting earthquake depths relative to the earth geoid surface (which is approximately mean sea level) instead of the previously used surface of the velocity model used to locate the events. Geoid depths have been determined for all events in the NCSS database from 1966 to the present. Requests for event information from the NCSS catalog will now return depths with respect to the geoid surface. This change is to comply with recently established USGS Advanced National Seismic Network (ANSS) convention regarding event depth reporting. Additional concurrent changes made to the NCSS earthquake information database are also described below.

More on The NCSS now reports earthquake depth relative to the geoid (sea level)


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The Northern California Earthquake Data Center (NCEDC) is a permanent archive and distribution center primarily for multiple types of digital data relating to earthquakes in central and northern California. The NCEDC is located at the Berkeley Seismological Laboratory, and has been accessible to users via the Internet since mid-1992. The NCEDC was formed as a joint project of the Berkeley Seismological Laboratory (BSL) and the U.S. Geological Survey (USGS) at Menlo Park in 1991, and current USGS funding is provided under a cooperative agreement for seismic network operations.

World map of NCEDC data distribution
World map of NCEDC data distribution (Click to view larger.)

Time series data come from broadband, short period, and strong motion seismic sensors, and geophysical sensors such as electromagnetic sensors, strain meters, creep meters, pore pressure, water level, and wind speed sensors. Earthquake catalogs can include time, hypocenter, magnitude, moment tensor, mechanisms, phase arrivals, codas, and amplitude data. GPS data are available in both raw observables and RINEX formatted data.

The NCEDC also provides support for earthquake processing and archiving activities of the Northern California Earthquake Management Center (NCEMC), a component of the California Integrated Seismic Network (CISN). The CISN is the California regional organization of the Advanced National Seismic System (ANSS).

The NCEDC is managed by Douglas Neuhauser under the direction of the BSL Director Richard Allen. Stephane Zuzlewski, Mario Aranha, Taka'aki Taira, Jennifer Taggart, Clay Miller, and Peggy Hellweg of the BSL and Lind Gee, Hal Macbeth, Lynn Dietz, and Fred Klein of the USGS Menlo Park contribute to the operation of the NCEDC.

If you use data from the NCEDC, we ask that you acknowledge the data center and the organizations that contributed the data.

We encourage you to contact us with questions, comments and feedback concerning the NCEDC. You can reach us vis email at or fill out our comments form.