Facebook’s Displacement Maps track daily movements of populations displaced by disasters

By Kyle Wiggers

Quantifying the proportion of displaced people and their locations in the wake of natural disasters is often a Sisyphean task. In an effort to furnish humanitarian organizations and government agencies alike with better information, Facebook today launched a new version of its Displacement Maps that calculates displacement levels on a daily cadence.

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The improved Displacement Maps — which come roughly a year after the initial version was released as a part of Facebook’s Disaster Maps product suite — was co-developed by the Norwegian Refugee Council’s Internal Displacement Monitoring Centre. It taps aggregated and de-identified data from users of Facebook’s cross-platform apps who have opted into location history. And unlike the previous version, it doesn’t struggle to distinguish among displaced people and those traveling after a disaster for work or leisure.

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Facebook says Displacement Maps now analyzes the patterns of people in areas affected by natural disasters that exhibit “abrupt changes” in their movement patterns, aggregated to a city level. It first studies normal movement patterns in the 30-day period before the crisis to establish a baseline. Then, it looks at patterns in the two-week period after the crisis and compares them with the pre-crisis patterns, calculating and comparing people’s home location and their typical distance traveled away from home for both time periods.

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Starting on day 15 after the crisis, Displacement Maps generates daily updates of the population status to count the number of people displaced and returned within and across cities, aggregating to a country level when the city count is too low. Folks originally classified as displaced are considered “returned” once they’re observed for three days in a row less than two kilometers away from their home.

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