1985 Mexico City earthquake

The 1985 Mexico City earthquake struck in the early morning of 19 September at 07:17:50 (CST) with a moment magnitude of 8.0 and a maximal Mercalli intensity of IX (Violent). The event caused serious damage to the Greater Mexico City area and the deaths of at least 5,000 people. The sequence of events included a foreshock of magnitude 5.2 that occurred the prior May, the main shock on 19 September, and two large aftershocks. The first of these occurred on 20 September with a magnitude of 7.5 and the second occurred seven months later on 30 April 1986 with a magnitude of 7.0. They were located off the coast along the Middle America Trench, more than 350 kilometres (220 mi) away, but the city suffered major damage due to its large magnitude and the ancient lake bed on which Mexico City sits. The event caused between three and five billion USD in damage as 412 buildings collapsed and another 3,124 were seriously damaged in the city.

Then-president Miguel de la Madrid and the ruling Institutional Revolutionary Party (PRI) were widely criticized for what was perceived as an inefficient response to the emergency, including an initial refusal of foreign aid.

Preface

Much of Mexico's volcanic and seismic activity stems from the movement of the North American plate against the Cocos and Pacific plates and it is one of the most active trenches in the world. Each year more than 90 tremors above magnitude 4.0 are recorded in this zone.