GLOBAL POSITIONING SYSTEM RESURVEY OF SOUTHERN CALIFORNIA SEISMIC NETWORK STATIONS

Systematic errors in travel-time data from local earthquakes can somet imes be traced to inaccuracies in the published seismic station coordi nates. This prompted a resurvey of the stations of the Caltech/USGS So uthern California Seismic Network (SCSN) using the Global Positioning System (GPS). We surveyed 241 stations of the SCSN using Trimble and A shtech dual-frequency GPS receivers and calculated positions accurate to 3 m using differential positioning from carrier phase measurements, Twelve percent of the stations that were surveyed were found to be mi slocated by more than 500 m. Stations of the TERRAscope and USC networ ks were also surveyed, as well as a network of portable seismic statio ns deployed shortly after the 1992 Joshua Tree and Landers earthquakes . The new coordinates and the offsets from the old coordinates are giv en below. The new coordinates are being used in SCSN locations as of 1 January 1994.