%0 Journal Article
%9 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES
%A Lacroix, Pascal
%T Landslides triggered by the Gorkha earthquake in the Langtang valley, volumes and initiation processes
%D 2016
%L fdi:010066697
%G ENG
%J Earth Planets and Space
%@ 1880-5981
%K Landslides ; Seismic triggering ; Nepal ; DEM ; SPOT ; Volumes ; Optical satellite photogrammetry ; Debris avalanche
%K NEPAL ; HIMALAYA
%M ISI:000372425700001
%P art. 46 [10 ]
%R 10.1186/s40623-016-0423-3
%U https://www.documentation.ird.fr/hor/fdi:010066697
%> https://www.documentation.ird.fr/intranet/publi/2016/04/010066697.pdf
%V 68
%W Horizon (IRD)
%X The Gorkha earthquake (Nepal, 2015, M-w 7.9) triggered many landslides. The most catastrophic mass movement was a debris avalanche that buried several villages in the Langtang valley. In this study, questions are raised about its volume and initiation. I investigate the possibility of high-resolution digital surface models computed from tri-stereo SPOT6/7 images to resolve this issue. This high-resolution dataset enables me to derive an inventory of 160 landslides triggered by this earthquake. I analyze the source of errors and estimate the uncertainties in the landslide volumes. The vegetation prevents to correctly estimate the volumes of landslides that occured in vegetated areas. However, I evaluate the volume and thickness of 73 landslides developing in vegetated-free areas, showing a power law between their surface areas and volumes with exponent of 1.20. Accumulations and depletion volumes are also well constrained for larger landslides, and I find that the main debris avalanches accumulated 6.95 x 10(6) m(3) of deposits in the valley with thicknesses reaching 60 m, and 9.66 x 10(6) m(3) in the glaciated part above 5000 m asl. The large amount of sediments is explained by an initiation of the debris avalanche due to serac falls and snow avalanches from five separate places between 6800 and 7200 m asl over 3 km length.
%$ 066 ; 064 ; 126