APPORT DE LA TÉLÉDÉTECTION À L'ÉTUDE DES FAILLES ACTIVES ET DES RISQUES SISMIQUES AU NORD DU VIÊT-NAM

In this paper, we present the results of a study of active fault segments, their characteristics and seismic hazard assessment. The Red river fault and the Dien Bien Phu fault are the most active faults in North Vietnam. We used Landsat-7 ETM+, SPOT-4 HRVIR, ERS-1 RSO, ERS-2 RSO images and aerial photographs to determine active fault lengths, their characteristics and to measure horizontal displacements accumulated during the Holocene. For this purpose, we interpreted the fault geomorphology and used directional filtering over SPOT-4 HRVIR and Landsat-7 ETM+ images combined with a digital elevation models derived from topographic data and the radar images. These parameters were then used to estimate maximum credible earthquake magnitude and peak ground acceleration. We integrated these results with the geomorphologic features, digital terrain models, earthquake epicentres and stress fields within a geographical information system (GIS).