Japan Geoscience Union Meeting 2016

Presentation information


Symbol A (Atmospheric and Hydrospheric Sciences) » A-CC Cryospheric Sciences & Cold District Environment

[A-CC20] Glaciology

Wed. May 25, 2016 1:45 PM - 3:15 PM 102 (1F)

Convener:*Tetsuo Ohata(Arctic Environment Research Center, National Institute of Polar Research), Masahiro Hori(Earth Observation Reseacrh Center, Japan Aerospace Exploration Agency), kazuyoshi suzuki(Japan Agency for Marine-Earth Science and Technology), Shin Sugiyama(Institute of Low Temperature Science, Hokkaido University), Chair:Takayuki Nuimura(Chiba Institute of Science)

2:30 PM - 2:45 PM

[ACC20-04] Remote sensing observations for a catastrophic avalanche collapse in Langtang induced by the Gorkha, Nepal earthquake

*Hiroto Nagai1, Manabu Watanabe1, Naoya Tomii1, Takeo Tadono1, Shinichi Suzuki1 (1.Japan Aerospace Exploration Agency)

Keywords:the Gorkha, Nepal earthquake, avalanche, PALSAR-2, ALOS, WorldView-3, remote sensing

We demonstrated an assessment of the sediments caused by a catastrophic avalanche, induced by the main shock of the 2015 Gorkha Earthquake in Nepal. Calculation of decreasing coherence and visual interpretation of amplitude images by means of the Phased Array-type L-band Synthetic Aperture Radar-2 (PALSAR-2) have a high potential for delineating the hazardous zone. These delineated outlines area highly consistent with that from a high-resolution optical image of WorldView-3 (WV-3). The delineated sediment collapse areas were estimated as 0.63 km2 (PALSAR-2 coherence calculation), 0.73 km2 (PALSAR-2 visual interpretation), and 1.09 km2 (WV-3), respectively. In the WV-3 image, surface features were classified into 15 segments, with the flowing, scattering, and other characteristics implying different physical properties; the different features suggest sequential collapse from multiple sources. Differences in the surface elevations of the collapse events estimated the total volume of the sediments as 5244.5 ×103 m3, with a error possibility between 3652.4×103 to 10687.4×103 m3, most of which are distributed along the river bed and the water stream. Further elevation measurements after ice/snow melting would reveal a contained volume of melting ice and snow, which will contribute to numerical avalanche simulation and source considerations.