Tectonic interpretation of the Trans-Mexicano Volcanic Belt

Although some workers interpret subduction along the Middle America Trench to be directly associated with volcanism in the Trans-Mexico Volcanic Belt, geographic distribution of intermediate-depth earthquakes, analysis of Sn propagation, and a limited number of focal-mechanism solutions suggest that the belt is largely independent of subduction. These data, in conjunction with the position of the volcanic belt with respect to known plate boundaries in the region, suggest that the belt represents the incompletely developed northern boundary of a developing micro-plate. It is a zone of transtension that probably results from slightly different rates of absolute plate velocities in the region.