title: Rapid and Near Real-Time Assessments of Population Displacement Using Mobile Phone Data Following Disasters: The 2015 Nepal Earthquake.
abstract: BACKGROUND
  Sudden impact disasters often result in the displacement of large numbers of people. These movements can occur prior to events, due to early warning messages, or take place post-event due to damages to shelters and livelihoods as well as a result of long-term reconstruction efforts. Displaced populations are especially vulnerable and often in need of support. However, timely and accurate data on the numbers and destinations of displaced populations are extremely challenging to collect across temporal and spatial scales, especially in the aftermath of disasters. Mobile phone call detail records were shown to be a valid data source for estimates of population movements after the 2010 Haiti earthquake, but their potential to provide near real-time ongoing measurements of population displacements immediately after a natural disaster has not been demonstrated.
  
  
  METHODS
  A computational architecture and analytical capacity were rapidly deployed within nine days of the Nepal earthquake of 25th April 2015, to provide spatiotemporally detailed estimates of population displacements from call detail records based on movements of 12 million de-identified mobile phones users.
  
  
  RESULTS
  Analysis shows the evolution of population mobility patterns after the earthquake and the patterns of return to affected areas, at a high level of detail. Particularly notable is the movement of an estimated 390,000 people above normal from the Kathmandu valley after the earthquake, with most people moving to surrounding areas and the highly-populated areas in the central southern area of Nepal.
  
  
  CONCLUSIONS
  This analysis provides an unprecedented level of information about human movement after a natural disaster, provided within a very short timeframe after the earthquake occurred. The patterns revealed using this method are almost impossible to find through other methods, and are of great interest to humanitarian agencies.
authors.affiliation: Flowminder Foundation, Stockholm, Sweden; Geography & Environment, University of Southampton, Southampton, UK.
authors.forename: Robin
authors.initials: R
authors.lastname: Wilson
authors.affiliation: Flowminder Foundation, Stockholm, Sweden; Geography & Environment, University of Southampton, Southampton, UK.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Zu Erbach-Schoenberg
authors.affiliation: Flowminder Foundation, Stockholm, Sweden; Faculty of Engineering & the Environment, University of Southampton, Southampton, UK.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Albert
authors.affiliation: Flowminder Foundation, Stockholm, Sweden; Electronics & Computer Science, University of Southampton, Southampton, UK.
authors.forename: Daniel
authors.initials: D
authors.lastname: Power
authors.affiliation: Flowminder Foundation, Stockholm, Sweden; Electronics & Computer Science, University of Southampton, Southampton, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Tudge
authors.affiliation: Flowminder Foundation, Stockholm, Sweden; Electronics & Computer Science, University of Southampton, Southampton, UK.
authors.forename: Miguel
authors.initials: M
authors.lastname: Gonzalez
authors.affiliation: Flowminder Foundation, Stockholm, Sweden; Politics & International Relations, University of Southampton, Southampton, UK.
authors.forename: Sam
authors.initials: S
authors.lastname: Guthrie
authors.affiliation: Flowminder Foundation, Stockholm, Sweden; Geography & Environment, University of Southampton, Southampton, UK.
authors.forename: Heather
authors.initials: H
authors.lastname: Chamberlain
authors.affiliation: Flowminder Foundation, Stockholm, Sweden; Geography & Environment, University of Southampton, Southampton, UK.
authors.forename: Christopher
authors.initials: C
authors.lastname: Brooks
authors.affiliation: Flowminder Foundation, Stockholm, Sweden; Electronics & Computer Science, University of Southampton, Southampton, UK; Oxford Internet Institute, University of Oxford, Southampton, UK.
authors.forename: Christopher
authors.initials: C
authors.lastname: Hughes
authors.affiliation: Flowminder Foundation, Stockholm, Sweden; Electronics & Computer Science, University of Southampton, Southampton, UK.
authors.forename: Lenka
authors.initials: L
authors.lastname: Pitonakova
authors.affiliation: Flowminder Foundation, Stockholm, Sweden; Center for Communicable Disease Dynamics, Harvard T.H. Chan School of Public Health, Boston, USA; Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, USA.
authors.forename: Caroline
authors.initials: C
authors.lastname: Buckee
authors.affiliation: Flowminder Foundation, Stockholm, Sweden; Department of Public Health Sciences, Karolinska Institute, Stockholm, Sweden; College of Information System and Management, National University of Defense Technology, Changsha, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Lu
authors.affiliation: Flowminder Foundation, Stockholm, Sweden; Stockholm School of Economics, Stockholm, Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Wetter
authors.affiliation: Flowminder Foundation, Stockholm, Sweden; Geography & Environment, University of Southampton, Southampton, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Tatem
authors.affiliation: Flowminder Foundation, Stockholm, Sweden; Dept. of Public Health Sciences, Karolinska Institute, Sweden.
authors.forename: Linus
authors.initials: L
authors.lastname: Bengtsson