Stress field and seismotectonics of northern South America

Abstract

We have integrated in situ stress, neotectonic, and Global Positioning System data to investigate the complex interactions among the South American, Caribbean, and Nazca plates and the Costa Rica–Panama microplate and to examine different seismotectonic models that have been proposed for the region. The resulting data set was used to generate an integrated stress map of the region that shows that the stress field in northern South America varies systematically in both orientation and relative magnitude. In the southwestern part of the study area, the Ecuadorian Andes stress province exhibits strong E-W compression resulting from the subduction of the Nazca plate beneath the South American plate. In the North Andes stress province, the observed NW-SE compression may result from the convergence between the Caribbean and the South American plates and/or the negative buoyancy of the already subducted Caribbean plate beneath northwestern South America. Possible convergence between the Costa Rica–Panama microplate with respect to northwestern South America may also be a source of compression in this region. In north and northeastern Venezuela, normal and strike-slip faulting with a NE-SW direction of extension characterizes the San Sebastian–El Pilar stress province.