The epicenter of the October 3, 1974, earthquake was 80 km west of Lima at 12.2°S and 77.67°W. This earthquake caused severe damage in Lima and vicinity, producing a maximum Modified Mercalli intensity of IX in a few small scattered areas in Lima. The Modified Mercalli intensity in Lima varied from V to IX; in towns south of Lima the intensity exceeded VIII. The areas of high intensity, both in Lima and along the coast, appear to be related to unfavorable soil conditions or to a high water table, as is evident in the areas where large damage and/or differential settlement took place. Slumping was also observed along the coastal road south of Lima. In Callao differential earth settlement was associated with liquefaction of the soil. Pockets of high intensities, such as in the districts of La Molina and Chorrillos, are correlated with possible local ground-amplification effects. Subsidence of up to 35 cm took place in some areas along the wave-cut terrace in Miraflores, and 15 cm of subsidence was observed in Chorrillos. The isoseismal map constructed for Lima can be used in a preliminary zonation of Lima for potential earthquake effects.