Locations of 113 aftershocks of the magnitude-7.6 (M_s) Peruvian earthquake of October 3, 1974, were determined from data obtained by a ten-station network installed along the coastal area between lat 11° and 14° S. These epicenters define an irregular shaped zone approximately 210 km long by 150 km wide, the oceanward or long side of which trends subparallel with the coast and extends between about lat 12° and 13.8° S. The distribution of hypocenters ranges in depth from near surface to roughly 65 km and is indicative of shallow underthrusting. Focal mechanisms are consistent with low angle thrust faulting. A b value of approximately 0.90 was determined for earthquakes within the Peruvian shallow seismic belt (1963-1975) and the aftershock sequence. / Master of Science