Current active front of the Central Andes at Mendoza city latitude (32º50ʼ-33ºS).

Abstract

Current active front of the Central Andes comprises part of the western piedmont of the city of Mendoza, where more than 800,000 people are established. Despite this, a comprehensive study of active faults mainly as potential seismogenic sources is lacking in this crucial sector of the Andean foreland. The present study attempts to outwit this shortcoming by characterizing the main Quaternary structures and integrating them in a structural-kinematic model developed from three balanced structural cross-sections. The foreland deformation at the study area is characterized by a population of N-S to NNE striking reverse faults, whose detachment level will be located in the Pre Silurian basement, constituting a thick skin thrust front. The series of thrusts, rooted at a 10-11 km-depth detachment, corresponds to Melocotón and Divisadero Largo faults showing surficial expression, and a blind fault called Maure, inferred om the structural-kinematic model. The Maure blind fault transfers shortening to the west-vergent thin-skinned Cerro de la Gloria thrusts, thus forming a triangular deformation zone. According to morphometric features of these active faults, a probable maximum earthquake magnitude ranges from Mw 5.4 to 6.8. Furthermore, strike slip faults with NW-SE strike are cutting Cerro de la Gloria fault system. Results were contrasted with ground data and focal mechanisms of surficial local earthquakes.