Numerous small earthquakes occur each day in the Coast Ranges of central California. The detailed study of these earthquakes provides a tool for gaining insight into the tectonic and physical processes responsible for the generation of damaging earthquakes. This catalog contains the fundamental parameters for earthquakes located within and adjacent to the seismograph network operated by the U.S. Geological Survey (USGS), during the third quarter of 1977.

The motivation for these detailed studies has been described by Pakiser and others (1969) and by Eaton and others (1970). Similar catalogs of earthquakes for the years 1969, 1970, and 1971 have been prepared by Lee and others (1972b, c and d). Catalogs for the first, second, third, and fourth quarters of 1972 and the first, second, third and fourth quarters of 1973 have been prepared by Wesson and others (1972a, b, 1973b, and 1974a and b), by Bufe and others (1975), and by Lester and others (1976a and b). Catalogs for the years 1974, 1975 and 1976 and the first quarter of 1977 have been prepared by Lester and Meagher (1978), by McHugh and Lester (1978 and 1979) and by Marks and Lester (1980a and 1980b). The basic data contained in these catalogs provide a foundation for further studies.

This catalog contains data on 855 earthquakes in central California. Arrival times at 205 seismograph stations were used to locate the earthquakes listed in this catalog. Of these 193 were telemetered stations operated by USGS. Readings from the remaining 12 stations were obtained through the courtesy of the Seismographic Stations, California Institute of Technology, Pasadena, University of California, Berkeley (UCB), and the California Department of Water Resources, Sacramento.

The Seismographic Station of the University of California, Berkeley, has for many years published a bulletin describing earthquakes in northern California and the surrounding area and listing readings at UCB stations from more distant events. The purpose of the present catalog is not to replace the UCB Bulletin, but rather to supplement it, by describing the seismicity of a portion of central California in much greater detail.