2002 Denver Annual Meeting (October 27-30, 2002)

Paper No. 3
Presentation Time: 8:00 AM-12:00 PM


TORRES-VERA, Marco Antonio, Laboratorio de Sistemas de Informacion Geografica y Percepcion Remota, Instituto de Geografia, UNAM, Circuito de Institutos, Ciudad Universitaria, Mexico, 04510, Mexico, matv@igiris.igeograf.unam.mx

Mexico has a long history of earthquakes. The first recorded earthquake in the history of Mexico was before 1500, (i.e. more than 400 years ago). If we need to predict earthquakes or the effects, hazards, destruction and casualties, we need to study historical seismicity and understand those effects, the destruction and the mechanisms that produced the earthquakes. In geology, there is a phrase that says, "The past is the key to the present". The first step to use this "past" to open the door to the present and understand the future is to study information of the historical seismicity, to determine the propagation, epicenters and micro zoning or maybe special places with specific effects or amplification, such as Mexico City. Here we present a study of the historical seismicity on the Pacific Coast that includes, location, magnitude and maps of isointensities to make a micro zoning and define high-risk zones. It will help us also to understand the effects that were observed in recent events such as the 1985 earthquake, which killed around 10,000 people in Mexico City alone, and why is it that Mexico City is more dangerous than other cities closer to the epicenter. This study includes the historical seismicity in Mexico from 1568 to 1837, in order to know where the highest risk areas are located. During this period, eleven earthquakes occurred that were reported in various works about Mexico. These references are documents from the Church council, papers on Seismicity or Vulcanology, and government sources. The references needed a certain degree of interpretation because they were either uncertain or incorrect. After the selection of information, maps of isointensities were prepared to determine the epicenters. The information about isointensities and epicenters was interpreted to determine the highest risk zones and the consequential damage. The results of this work provide valuable information for disaster prevention and saving lives and the map of epicenters was useful to determine the places where most earthquakes happen and where the probability of having an earthquake is highest.