LSH CATALOG FOR SOUTHERN CALIFORNIA

This directory contains earthquake locations using southern California pick and waveform data from 1981 to 2005.

The catalog is described in:

Lin, G., P. M. Shearer, and E. Hauksson (2007),  Applying a three-dimensional velocity model, waveform cross correlation, and cluster analysis to locate southern California seismicity from 1981 to 2005, J. Geophys. Res., 112, B12309, doi:10.1029/2007JB004986.

A new 3D seismic velocity model is applied to improve absolute event locations, and the layer-avaraged 1D velocity model from this new 3D model is used in the waveform cross-correlation relocation. For more details about the 3D velocity model, please refer to

Lin, G., P. M. Shearer, E. Hauksson and C. H. Thurber (2007), A three-dimensional crustal seismic velocity model for southern California from a composite event method, J. Geophys. Res., 112, B11306, doi:10.1029/2007JB004977.

The following files should be in this directory:

LSH_1.12 --  File with locations (433166 events, about 61 Mbytes)

                     (see below for update details)

LSH_1.11 --  File with locations (433166 events, about 61 Mbytes)

LSH_1.1  --  File with locations (433166 events, about 61 Mbytes)

LSH_1.0  --  File with locations (426734 events, about 60 Mbytes)

                     (see below for format description)

locmap_LSH_1.0.jpg  --  Location map of relocated events.

                        The waveform cross-correlation locations are plotted in black;

                        the 3-D locations and 1-D SSST locations are colored by year.

Location file format description:

The locations are in the following custom format with 146 character lines:

1981  1  1  4 13 55.710   3301565 33.25457 -115.96695   5.840  2.20  23   5   0.08   1   4   579   626    2478   0.100   0.400   0.008   0.026  le

year mo dy hr mn  sec     cuspid   qlat      qlon        qdep  qmag  np  ns   rms   day     clnum nclst   ndif   aer_h   aer_z   rer_h   rer_z

where

      1981 = year

         1 = month

         1 = day

         4 = hour

        13 = minute

    55.710 = second

   3301565 = SCSN cuspid (up to 9 digits)

  33.25457 = latitude

-115.96695 = longitude

     5.840 = depth (km)

      2.20 = SCSN assigned magnitude (0.0 if unassigned)

        23 = number of P picks used for 1D SSST or 3D location

         5 = number of S picks used for 1D SSST or 3D location

      0.08 = rms residual (s) for 1D SSST location

         1 = local day/night flag (=0 for day, =1 for night in Calif.)

         4 = location method flag (=1 for SCSN catalog,  =2 for 1D SSST,  =3 for 3D, =4 for waveform cross-correlation)

       579 = similar event cluster identification number (0 if the event is not relocated with waveform cross-correlation data)

       626 = number of events in similar event cluster (0 if the event is not in similar event clusters)

      2478 = number of differential times used to locate this event

     0.100 = est. std. error (km) in absolute horz. position

     0.400 = est. std. error (km) in absolute depth

     0.008 = est. std. error (km) in horz. position relative to other events in cluster

     0.026 = est. std. error (km) in depth relative to other events in cluster

        le = SCSN flag for event type (le=local, qb=quarry)

Notes:

(1)  There are no events flagged as 1 for the location method flag. We only included relocated events.

(2)  322080 (75%) of the locations are in similar event clusters and use the waveform cross-correlation times.

(3a) There are 24 events below 36.0 km depth, which are deeper than the maximum depth of events in southern California.

(3b) The depths of quarry blasts range between 0.0 km and 39.0 km. The peak is around 1.0 or 2.0 km depth.

        The unreliable depths may be caused by some wrong initial locations and they have large location errors.

(4)  The location errors are set to 99.000 if they are not available.

(5)  The day/night flag is based on UT=3 to 15 being "night" in Calif.

Updates:

(1) CHANGES FOR the LSH_1.1 CATALOG (02-Apr-2007)

LSH_1.0 catalog only includes relocated events with waveform data.

LSH_1.1 catalog includes all the events from 1981 to 2005 with phase data and with or without waveform data. This results in more 1-D and 3-D relocated events than the LSH_1.0 catalog.

Thanks to Zhigang Peng for discovering an event gap related to this issue.

(2) CHANGES FOR the LSH_1.1* CATALOGS

    (2a) LSH_1.11 CATALOG (19-Apr-2007)

    (2b) LSH_1.12 CATALOG (30-May-2007)

Minor timing issues for 17 events in LSH_1.11 and 54 events in LSH_1.12 are corrected. This should not affect most users of the catalog.

Thanks to Daniel Scheirer and Andreas Plesch for pointing out these problems.

(3) The 2004 Parkfield mainshock and some aftershocks are treated as regional events in the Southern California Seismic Network. Since the LSH catalog only includes local events and quarry blasts, the Parkfield maishock is not in this catalog.