Preliminary catalog of earthquakes in northern Imperial Valley, California, January 1, 1977 to March 31, 1977

The northern section of the Imperial Valley region in Southern California is an area of known geothermal resources and an area of high seismicity. To study in detail the relationship between geothermal areas and earthquakes, the U.S. Geological Survey has been monitoring seismicity in the Imperial Valley with a sixteen station network since 1973. Six new stations were added to the network in November 1976. This catalog contains a description of the network and a list of preliminary data on earthquakes recorded by the network from January 1977 through March 1977.