NEW DATA ON THE GEODYNAMICS OF SOUTHERN PERU FROM COMPUTERIZED ANALYSIS OF SPOT AND SAR ERS-1 IMAGES

Several geological structures are extracted from SPOT-Panchromatic and ERS-1 radar images of the Central Andes (Arequipa area, Southern Peru ), Our new methodology of numerical image processing is an aid for ide ntification of the structures, This numerical approach helps to locate , characterize and determine the amplitude of the vertical offset of s tructures, The results show that the NW-SE-trending major faults are p rincipally normal with a small sinistral strike-slip component. The op en NE-SW faults are tension gashes. Extension in the studied area tren ds NE-SW and the major NW-SE-striking faults form an extensional ''en echelon'' pattern including an active volcanic zone. These new kinemat ic results lead to a regional geodynamic model which takes into accoun t oblique convergence between Pacific and South America Plates within the Wadati-Benioff zone of the Peru trench.