Bosquejo sismotectonico del sur de mexico

The seismic zone of southern Mexico can be divided in four regions of different characteristics even though the seismic activity as a whole is considered as a result of the interaction among the Pacific, Northamerica, Cocos, Caribbean and Rivera plates. In this paper some of the differences are shown. The Isthmus of Tehuantepecand the coast of Chiapas are the best differenciated regions. For the remaining regions: Oaxaca, Guerrero-Michoacan and Jalisco-Colima some peculiarities resulting from the analysis of seismicity and some focal mechanismssolutions are shown. Thus, the Isthmus of Tehuantepec-Chiapas region seems to be a transition between a zone of normal subduction (Central America) and an anomalous one (Oaxaca) which is comparable to the central part of Peru in South America. The Guerrero-Michoacan region shows some complications that can be attributed to the proximity of the interception of the East Pacific Ridge, the Acapulco trench and the Rivera fault. The Jalisco-Colima region shows a marked reduction in the frequency of occurrence of seismic activity.