Geomorphic and geologic controls of geohazards induced by Nepal's 2015 Gorkha earthquake
The Gorkha earthquake (M 7.8) on 25 April 2015 and later aftershocks struck South Asia, killing ~9,000 and damaging a large region. Supported by a large campaign of responsive satellite data acquisitions over the earthquake disaster zone, our team undertook a satellite image survey of the earthquakes' induced geohazards in Nepal and China and an assessment of the geomorphic, tectonic, and lithologic controls on quake-induced landslides. Timely analysis and communication aided response and recovery and informed decision makers. We mapped 4,312 co-seismic and post-seismic landslides. We also surveyed 491 glacier lakes for earthquake damage, but found only 9 landslide-impacted lakes and no visible satellite evidence of outbursts. Landslide densities correlate with slope, peak ground acceleration, surface downdrop, and specific metamorphic lithologies and large plutonic intrusions.
© 2015 American Association for the Advancement of Science. Received 20 June 2015; accepted 27 November 2015; Published Online December 16 2015. JSK, GJL, and UKH thank the NASA SERVIR Applied Science Team and NASA Cryosphere Program for support. DHS thanks the Hakai Institute for support. Part of this research was sponsored by the NASA Earth Surface and Interior focus area and performed at the Jet Propulsion Laboratory, California Institute of Technology. We gratefully acknowledge support from several "citizen scientists" who provided key observations and reports from various locations in Nepal: Deep Rai, JB Rai, Nabaraj Sapkota, Mauli Dhan Rai, and Mukhya Gotame, who made on-site inspections and photo documentation of Thulagi (Dona) Lake, Rolpa Lake, Kali Gandaki, and 'Lower Pisang' landslide dammed lake. ASTER data courtesy of NASA/GSFC/METI/Japan Space Systems, the U.S./Japan ASTER Science Team, and GLIMS. We especially laud DigitalGlobe's decision to acquire and make available a vast volume of data for analysis related to Gorkha earthquake response. We thank Cunren Liang for processing the ALOS-2 wide-swath interferogram. Original ALOS-2 data are © 2015 JAXA. This study was partially supported by core funds of ICIMOD contributed by the governments of Afghanistan, Australia, Austria, Bangladesh, Bhutan, China, India, Myanmar, Nepal, Norway, Pakistan, Switzerland, and the United Kingdom. The two chief databases produced by this work are available at ICIMOD (landslides - http://rds.icimod.org/Home/DataDetail?metadataId=24055 ; and glacial lakes - http://rds.icimod.org/Home/DataDetail?metadataId=24065).
Supplemental Material - Kargel-SM.pdf