Category: "Earthquake Depths"

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

October 7th, 2015
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… more »

Geoid Depth FAQ

October 7th, 2015
What is Geoid depth? The depth of an earthquake location can be reported relative to the mathematical geoid surface within the earth, which is very close to sea level. In simplified terms, the geoid is an imaginary surface within the earth… more »

Revision of NCSN Catalog

April 20th, 1997
April 29, 1997 On April 29, 1997, the USGS Northern California Seismic Network (NCSN) revised the format and relocated the entire earthquake catalog at the Northern California Earthquake Data Center. We undertook the catalog revision for the following… more »

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