Seismicity of the Socorro area of the Rio Grande rift
— Allan R. Sanford, Lawrence Jaksha, and Daniel Wieder

The Socorro area has long been recognized as a region of unusual seismic activity; the mode of occurrence is primarily in swarms and the intensity of earthquake activity, both in numbers and strengths, is the highest of any area along the Rio Grande rift (Bagg, 1904; Reid, 1911; Northrop, 1945 and 1947). Considerable effort has been devoted to documenting and understanding the seismicity of this region. Studies based primarily on reports of felt earthquakes, the only data available prior to 1960, have been published by Sanford (1963) and Northrop (1976). Papers emphasizing the results of instrumental studies are nu-merous, but those which best summarize the seismicity of the Socorro area and its relation to activity elsewhere along the rift are Sanford and others (1972) and Sanford and others (1979). The purpose of this paper is to review results of recent instrumental studies and to suggest a possible mechanism for the unusual seismicity of the Socorro area.