MULTISOURCE REMOTELY SENSED DATA, FIELD CHECKS AND SEISMICITY FOR THE DEFINITION OF ACTIVE TECTONICS IN ECUADORIAN ANDES

The active tectonics of the Ecuadorian Andes were analysed by the correlation of remotely sensed features, and microtectonic and seismological data. Landsat and radar imagery, and airborne stereophotos, were employed to investigate the fault pattern of scarcely accessible areas, with special reference to those lineaments showing young morphology, linear continuity and dragging effect on streams of post-glacial age. Some NNE-SSW long lineaments characterized by right-lateral strike-slip motions, were identified in the eastern Andes as probably very recent faults. Field microtectonic analysis was guided by remotely sensed data and allowed the reconstruction of the active tectonic compressional stress field characterized by a WSW-ENE trending sigma-1. It also confirmed the recent motions along the NNE-SSW set. These data are consistent with published focal mechanism solutions in the same area. The seismicity is explained by a kinematic model of the upper crust, in which west dipping oblique thrusts and strike-slip faults coexist in the eastern Andes. Following the remotely sensed data and the available literature this model is extended southwards to complete the regional geodynamic framework.