In response to the magnitude 7.8 earthquake that struck Nepal on 25 April 2015, the International Centre for Integrated Mountain Development (ICIMOD), National Aerospace and Space Administration (NASA), the University of Arizona, and their collaborators have coordinated an international volunteer team to map and assess hazards created by landslides, rockfalls, and avalanches. The NASA-U.S.Geological Survey-Interagency Volunteer Earthquake Response Team, which now numbers over 40 volunteers from eight different countries, has joined with the British Geological Survey-Durham University-Earthquakes without Frontiers team. Both groups use high-resolution satellite imagery made available by government and private sector agencies such as NASA, Japan Aerospace Exploration Agency (JAXA), and Digital Globe, and international groups such as the International Charter on Space and Major Disasters to identify landslides that have affected villages and landslide-dammed rivers that could lead to severe downstream flooding if the dam is suddenly breached. Given the large loss of life and property during and after the earthquake, ICIMOD and its collaborators aim to provide knowledge that can help prevent future disasters in the affected areas.

A rapid analysis report about geohazards in the aftermath of the earthquake was shared with the Government of Nepal on 7 May 2015.

To date, the response teams have identified over 3,000 landslides, and assembled a database of over 250 identified landslides and other large mass movements, focusing specifically on those that were generated by the earthquake and its aftershocks or other secondary effects.

The NASA-USGS-Interagency team examined five events in particular that have either devastated villages or present a significant risk to downstream communities:

• the Gyriong Zangbo/Trishuli River near Chongsecun, China;
• the Marshygandhi River near Pisang, Nepal
  (http://www.nasa.gov/jpl/hazardous-landslide-dammed-lake-pisang-annapurna-region-nepal);
• the Tom Khola near Prok, Nepal
  (http://www.nasa.gov/jpl/ landsat-shows-new-hazards-arising-in-manaslulangtang-region-of-nepal);
• the Budi Gandaki River near Lho Bazaar, Nepal; and
• Langtang Village, Nepal
  (http://mountainhydrology.org/nepal-quake/landsat-8-reveals-extent-of-earthquake-disaster-in-langtang-valley/).

The BGS-Durham-EWF team has also identified a zone of widespread, intense landsliding that runs east-west, approximately parallel to the transition between the Lesser and High Himalaya. This zone contains numerous rockfalls and debris avalanches, which are individually localised but together have had catastrophic impacts on roads and villages.

The landslide database will be continually updated with new information from these teams as well as colleagues in the Chinese Academy of Sciences, and shared with local governments and agencies coordinating the delivery of aid and assistance. The database is available as kml files on the right side of this page under download box, and galleries of earthquake-related case studies and maps are available here, here and here. To assist with post-earthquake recovery, ICIMOD and the international scientific community will continue to monitor landslide-dammed rivers, secondary landslides, and the development of future landslide hazards as the monsoon draws near.

Contacts:

Joseph Shea
(ICIMOD; joseph.shea@icimod.org)

Greg Leonard
(University of Arizona; gleonard@email.arizona.edu)

Jeffrey Kargel
(University of Arizona; jeffreyskargel@hotmail.com)

Alex Densmore
(Durham University/Earthquakes without Frontiers; a.l.densmore@durham.ac.uk)

Colm Jordan
(British Geological Survey; cjj@bgs.ac.uk)

Dalia Kirschbaum
(dalia.b.kirschbaum@nasa.gov)

Nira Gurung

nira.gurung@icimod.org

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