Large earthquake-triggered landslides and mountain belt erosion: The Tsaoling case, Taiwan

The 1999 Chi-Chi earthquake triggered the catastrophic Tsaoling landslide in central Taiwan. We mapped the landslide area and estimated the landslide volume, using high-resolution digital elevation model from airborne LiDAR (Light Detection and Ranging), satellite images, aerial photographs and topographic maps. The comparison between cut and fill volumes, about 0.126 and 0.150 km3, respectively, suggests a volume increase of 19% due to decompaction during landsliding. In April 2002, the cut and fill volumes were about 0.137 and 0.116 km super(3), respectively. These estimates suggest that 2.5 years after the event, the volume of landslide debris removed by river erosion was nearly 0.045 km3. Such a large value highlights the importance of landslide processes for erosion and long-term denudation in the Taiwan mountain belt.Original Abstract: En 1999, le seisme de Chi-Chi a declenche un glissement de terrain catastrophique a Tsaoling, dans le centre de Taiwan. Nous avons cartographie le site et estime le volume deplace, en utilisant un modele numerique a haute resolution LiDAR (Light Detection and Ranging, aeroporte), des images satellites, photographies aeriennes et cartes topographiques. Le bilan des volumes evacue et accumule, environ 0,126 et 0,150 km super(3), respectivement, indique une augmentation de volume de 19 %, due a la decompaction pendant le glissement de terrain. En avril 2002, ces volumes etaient devenus environ 0,137 et 0,116 km super(3). Ces evaluations suggerent que, 2,5 ans apres l'evenement, le volume de debris enleve par erosion de la riviere atteint presque 0,045 km super(3). Une si grande valeur accentue l'importance des processus de glissements de terrain pour l'erosion et la denudation a long terme dans la chaine de montagnes de Taiwan.