Satellite-based emergency mapping using optical imagery: experience and reflections from the 2015 Nepal earthquakes

Williams, J.G.; Rosser, N.J.; Kincey, M.E.; Benjamin, J.; Oven, K.J.; Densmore, A.L.; Milledge, D.G.; Robinson, T.R.; Jordan, C.A.; Dijkstra, T.A.

Abstract

Landslides triggered by large earthquakes in mountainous regions contribute significantly to overall earthquake losses and pose a major secondary hazard that can persist for months or years. While scientific investigations of coseismic landsliding are increasingly common, there is no protocol for rapid (hours-to-days) humanitarian-facing landslide assessment and no published recognition of what is possible and what is useful to compile immediately after the event. Drawing on the 2015 Mw 7.8 Gorkha earthquake in Nepal, we consider how quickly a landslide assessment based upon manual satellite-based emergency mapping (SEM) can be realistically achieved and review the decisions taken by analysts to ascertain the timeliness and type of useful information that can be generated. We find that, at present, many forms of landslide assessment are too slow to generate relative to the speed of a humanitarian response, despite increasingly rapid access to high-quality imagery. Importantly, the value of information on landslides evolves rapidly as a disaster response develops, so identifying the purpose, timescales, and end users of a post-earthquake landslide assessment is essential to inform the approach taken. It is clear that discussions are needed on the form and timing of landslide assessments, and how best to present and share this information, before rather than after an earthquake strikes. In this paper, we share the lessons learned from the Gorkha earthquake, with the aim of informing the approach taken by scientists to understand the evolving landslide hazard in future events and the expectations of the humanitarian community involved in disaster response.

Citation

Williams, J., Rosser, N., Kincey, M., Benjamin, J., Oven, K., Densmore, A., …Dijkstra, T. (2018). Satellite-based emergency mapping using optical imagery: experience and reflections from the 2015 Nepal earthquakes. Natural Hazards and Earth System Sciences, 18, 185-205. https://doi.org/10.5194/nhess-18-185-2018

• Journal Article Type: Article
• Acceptance Date: Dec 8, 2017
• Online Publication Date: Jan 16, 2018
• Publication Date: Jan 16, 2018
• Deposit Date: Dec 8, 2017
• Publicly Available Date: Jan 17, 2018
• Journal: Natural Hazards and Earth System Sciences
• Print ISSN: 1561-8633
• Electronic ISSN: 1684-9981
• Publisher: European Geosciences Union
• Peer Reviewed: Peer Reviewed
• Volume: 18
• Pages: 185-205
• DOI: https://doi.org/10.5194/nhess-18-185-2018
• Keywords: Coseismic landslides, Satellite-based emergency mapping, Landslide mapping, Disaster response.
• Public URL: https://durham-repository.worktribe.com/output/1369927