The Earthquake of Managua, Nicaragua, 1972

Abstract

THE earthquake occurred on December 23,1972, at 0630 GCT. It had a magnitude M_b=5.7 (M_s=6.1) and a superficial focus of about 5 km. The epicentral region, which did not exceed in diameter more than a few kilometres, comprised the central part of the city of Managua where, out of a population of 400,000, about 10,000 were killed. The earthquake and the fire that followed caused damage to property estimated at about £120 million. A strong-motion AR-240 recorder located about 7 km from the centre of the city, at the ESSO refinery, registered maximum ground accelerations of 40%g; the duration of severe shaking was about 6 s. The principal shock was preceded by a small foreshock and followed by many aftershocks of magnitude equal to or less than M_b=5.1.