PRELIMINARY RELEASE OF RECORDS OF THE
             NORTHRIDGE EARTHQUAKE (17 JANUARY, 1994) AT STATIONS
                    OF THE LOS ANGELES STRONG MOTION NETWORK

                                      by

                               M.I. Todorovska
                         Univ. of Southern California
                         Civil Engineering Department
                          Los Angeles, CA 90098-2531


      This directory contains a preliminary release of Volume I data of the
    Northridge earthquake (17 Jan., 1994) recorded at stations of the
    Los Angeles Strong Motion Network.     The network is maintained by
    M.D. Trifunac and M.I. Todorovska  of  Univ. of Southern California.

      The main event was recorded by 65 stations.    All the recordings are
    on 70 mm film by SMA-1 accelerographs.     A summary of uncorrected peak
    accelerations at these stations (a table and contours of equal acceleration)
    can be found in a paper by Trifunac et al., published in
    Soil Dynam. & Earathqu. Engng, Vol. 13, pp 187-196., 1994.
    The title of the paper is   "A note on distribution of uncorrected peak
    ground accelerations during the Northridge, California, earthquake of
    17 January 1994".

      The major portion of the funding for processing of these records came 
    from  USGS and NSF, via a grant to USC (Grant No. CMS 9416761, 
    PI:  M.I. Todorovska).   The award letter is dated 20 April, 1995.
    Other funding was provided by   US Navy Engineering Facility Center (Port
    Hueneme),   Dames & Moore,   City of Los Angeles Dept. of Water & Power, 
    Univ. of Southern California, and our colleague at USC Prof. J.P. Bardet.
    The support of all of these organizations and individuals is gratefully
    acknowledged.

      Volume I data contain digitized time histories of the instrument response,
    scaled in units seconds and g/10.    The records have been digitized by
    an HP scanner and a PC with resolution of 600 dpi or 300 dpi, using the
    system described in a USC report No. CE 90-03, by Lee and Trifunac (1990).
    The title of the report is "Automatic digitization and processing of
    accelerograms using PC.

      The files are named as    v1x****.usc.   The first two digits of the
    file number correspond to the USC station number.  To save space, the 
    files have been compressed by Norton's pkzip command under DOS operating 
    system.  The files can be uncompressed on a PC by using pkunzip program.

      The Volume I files contain:

         13 lines of text
         an array of integers icor(100),     format(16i5)
         an array of reals    fcor(50),      format(8f10.3)
         the time history ((t,y), i=1,npt),  format(1x,5(f7.4,f7.3))
         end of file (component)  mark

    with

         icor(28) =   number of points
         icor(27) =   comp. orientation in deg., clockwise from North
         fcor( 7) =   eq. latitude  (in degrees)
         fcor( 8) =   eq. longitude (in degrees)
         fcor( 9) =   stat. latitude  (in degrees)
         fcor(10) =   stat. longitude (in degrees)
         fcor(12) =   eq. magnitude
         fcor(14) =   eq. depth in km
         fcor(11) =   epicentral distance

      The header data contains full information about the station and the 
    record.   The following is some additional information that may be useful 
    for the user.   The vertical transducer at station USC #03 lost damping 
    and needs to be processed by a special procedure.  Station USC #51 
    recorded the main event in three segments.  These are stored in files 
    v1x5100.usc, v1x5101.usc and v1x5102.usc.   The time interval between 
    the end of the first segment and the beginning of the second segment is
    known, and is about 0.4 sec.  The time interval between the end of the 
    second segment and the beginning of the third segment is not known for 
    sure, but is probably no more than 0.6 sec.

      The user is advised to read this file carefully, and to refer to the 
    paper by Trifunac et. al (1994) for questions about the network.   All the
    information that is available regarding these recordings is either in
    the Volume I files, in the paper, or in this file.

      Users of these data are requested to acknowledge Professors Trifunac 
    and Todorovska from USC in future applications of these data.

    -------------------------------------------------------------------
    Prepared on  31 May, 1995

    Maria I. Todorovska
    KAP 216A
    Civil Engineering Dept.
    Univ. of Southern California
    Los Angeles, CA 90089-2531