Evolution of the Mexican Seismic Alert System (SASMEX)

The seismic activity along the Mexican coastline, where the Cocos, Rivera, and Pacific plates collide with the North American plate, represents the source of most of the strong earthquakes experienced by the different civilizations that have developed over the centuries in the Mexican territory, as documented by the inhabitants of the Valley of Mexico prior to the arrival of the Spaniards (Figure 1), who referred to an earthquake that occurred in the year Uno Pedernal (One Flint), corresponding to the year 1480 (Suarez and Acosta 1996). The Pacific Mexican coast, consisting of the states of Jalisco, Colima, Michoacan, Guerrero, Oaxaca, and Chiapas, is part of the so called fire belt and has been regarded as one of the regions with the highest seismic activity in the world. From 1875 to 2008 more than 160 large earthquakes (magnitude M > 6.5) occurred in this region (Figure 2). One of the major seismic catastrophes in recent Mexican history took place the morning of 19 September 1985 in Mexico City, resulting from the ground motion amplification of the M 8.1 earthquake that occurred off the coast of Michoacan. The effects of that earthquake caused at least 10,000 deaths and 30,000 injuries in Mexico City, which is located about 400 km away from the epicenter. The analysis of seismic records from that event allowed scientists to determine that the effect of the energy in the subsoil of Mexico City induced resonance in the structure of several buildings, which caused their collapse and the high toll in casualties; in addition, neither early warnings nor previous training for a quick emergency response in case of a major earthquake were available (Esteva 1988). After experiencing the serious seismic effects of the 1985 earthquake, both national and international experts recommended initiatives to learn from the …