NCSN(5Q)          Misc. Reference Manual Pages           NCSN(5Q)



NAME
     NCSN, ncsn, calnet - description of USGS Northern California
     Seismic  Network  (NCSN)  data  at  the  Northern California
     Earthquake Data Center (NCEDC)

DESCRIPTION
     The Data Center stores the following  types  of  data  which
     were recorded by NCSN:

     1.   catalog listings from 1968 to the present.

     2.   phase listings from 1968 to the present.

     3.   digital seismograms (grm files) for local, regional and
          teleseismic events.

     4.   mem files - contain the  binary  event  parameters  and
          pointers to individual traces in the grm files.

     5.   ascii mem files -  ascii version of the mem files.

     6.   NCSN    parameters    -    station     locations     in
          /data/dc1/ncsn/parameters/ncsn.stations.


     Catalog and Phase Data

     The catalog and  phase  data  consists  of  data  from  1968
     through the present.  The catalog is comprised of earthquake
     locations based on P and S arrival  time  data  from  analog
     microfilm  records  (pre-1984),  the Real-Time-Pickers (RTP)
     (1981 and after), the CalTech-USGS-Seismic-Processing System
     (CUSP)  (1984  and after), as well as arrival time data from
     deployments of portable seismographs.  In addition,  arrival
     time  data  for events recorded by the University of Nevada,
     the California Institute  of  Technology,  Tera  Corporation
     (Humbolt  Bay),  Pacific  Gas  &  Electric  Corporation, and
     Woodward-Clyde Consultants have been merged  into  the  NCSN
     database.  Both  individual Wood-Anderson amplitude measure-
     ments and the UCB catalog magnitudes were  merged  into  the
     NCSN  database  to provide an independent estimate of magni-
     tude. Because the CUSP and RTP  systems  detect  and  locate
     earthquakes independently, their data are merged together to
     generate a comprehensive catalog. CUSP data takes precedence
     over  RTP data for events which have data from both sources.
     The merged arrival time data is relocated using the  program
     HYPOINVERSE (Klein, 1989).

     The format for the catalog and  phase  data  is  HYPOINVERSE
     Shadow   format,   which   is  described  in  manual  pages,
     _n_c_s_n._c_a_t_a_l_o_g and _n_c_s_n._p_h_a_s_e.  The location  of  the  catalog
     and phase data is described in manual page _i_n_f_o.



SunOS 5.5.1        Last change: 26 April 1993                   1






NCSN(5Q)          Misc. Reference Manual Pages           NCSN(5Q)



     Program eqselect allows the user to select a subset  of  the
     catalog  satisgying  user defined criteria.  Program extract
     extracts the hypoinverse and phase information for  selected
     events from the online NCSN phase files.


     Digital Seismograms

     The digital seismograms were recorded with the CUSP  system,
     a  complete earthquake detection, location, and data manage-
     ment system developed by Carl Johnson of the  United  States
     Geologic  Survey.   The  seismograms  were  digitized at 100
     samples/sec with 12 bit A/D resolution. The  data  for  each
     event is contained in a mem and grm file in CUSP format.  At
     the data center, the grm  file  contains  the  demultiplexed
     waveform data in big-endian (eg SUN) byte order.

     Digital seismograms recorded during the period March 1984  -
     September 1990 may have missing data samples.  Program chktc
     is provided to identify the occurrence of missing samples.

     Retrieval of the grm and mem files is performed  using  pro-
     grams  getseis  and  getmem.  Program cusp2ah is provided to
     convert the grm and mem files to ahxdr format file.

     To retrieve grm and mem files, the cuspid of  the  event  is
     required.  The cuspid can be obtained in the catalog record.

     To convert the waveform files to CUSP VAX format:

     1)   Retrieve  the  seismogram  with   getseis   using   the
          uncompress option.

     2)   Then using the following command to convert to VAX btye
          order:

               dd if=cuspid of=xcuspid.grm conv=swab

          e.g. dd if=2053544 of=x2053544.grm conv=swab

     NOTE: When using ftp to transfer  the  data  files  to  your
     local computer, use the binary option.

     For more information, contact:

          Barbara      Bogaert,      bogaert@andreas.wr.usgs.gov,
          415-329-5001

AUTHOR
     Barbara Bogaert, USGS Menlo Park, California





SunOS 5.5.1        Last change: 26 April 1993                   2






NCSN(5Q)          Misc. Reference Manual Pages           NCSN(5Q)



SEE ALSO
     extract(1),     catalog(5),      ncsn(5)      ncsn.phase(5),
     ncsn.catalog(5), ncsn.stations(5)




















































SunOS 5.5.1        Last change: 26 April 1993                   3