NCEDC News/Blog

Changes to the NCSN/NCEDC catalog

Categories:   Data Access Methods  |  Northern California Earthquake Data Center (NCEDC)  |  USGS Northern California Seismic Network (NCSN)  |  Earthquake Catalogue  |  2004 Parkfield Earthquake  |  2003 San Simeon Earthquake  |  Catalogs

July 18, 2008 

The NCEDC has migrated all NCSN phase, catalog, and waveform information from ASCII files into the CISN database. This migration necessitated the following changes.

  • Formerly the catalog referenced historic events without waveforms for the period 1966/07 - 1998/12 using negative event ID numbers. During the migration of the catalog into the CISN database, all 228,690 negative event ID numbers were mapped to positive event ID numbers (download the file "2008-07-18.mapping" from http://ncedc.org/ftp/pub/doc/ncsn). In addition, on 2007/06/22 7,539 event ID numbers for earthquakes detected by NCSN real-time systems were reassigned to event ID numbers detected by the CUSP system but not yet reviewed by analysts. Most of the latter events are aftershocks of the San Simeon and Parkfield earthquakes. The association of the real-time arrival time data with the seismograms recorded by the CUSP system allows analysts to efficiently review these aftershocks and make the associated event waveform data available to the user community.
  • Channel names of seismograms (March 1984 - present) and phase data (July 1966 - present) have been mapped from a non-SEED Station Network Channel nomenclature to a SEED (Station Network Channel Location) nomenclature. The mapping of old (columns 9-12) to SEED (columns 127-129) is described in the NCSN Station List Format document. The channel name remapping includes another benefit besides the adoption of the standard SEED channel naming. We have deleted seismograms and phases from non-existent and discontinued stations, and we have renamed channels that were initially recorded under the wrong name. These now-corrected naming errors affected thousands of seismograms and phases, but probably did not corrupt many earthquake locations.
  • The NCSN/NCEDC catalog search interface now retrieves information from the NCEDC database rather than the original NCSN flat hypoinverse files.

The NCEDC apologizes for any inconvenience these changes cause. Please contact the NCEDC if you have any questions about these changes.