Landslides triggered by the Gorkha earthquake in the Langtang valley, volumes and initiation processes
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-resolutio...
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Veröffentlicht in: | Earth, planets, and space planets, and space, 2016-03, Vol.68 (1), p.1, Article 46 |
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Sprache: | eng |
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Zusammenfassung: | 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 × 10
6
m
3
of deposits in the valley with thicknesses reaching 60 m, and 9.66 × 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. |
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ISSN: | 1880-5981 1880-5981 |
DOI: | 10.1186/s40623-016-0423-3 |