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.
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.
Partners such as SEEDS India and the Harvard T.H. Chan School of Public Health have used previous versions of our displacement maps for disaster response and public health research, and we hope that our full list of over 100 NGO and research partners will be able to leverage these new maps to fulfill their missions, wrote Facebook researchers Eugenia Giraudy, Paige Maas, Shankar Iyer, Alex Dow, and Alex Pompe. As climate change increases the frequency and severity of natural disasters, response organizations require improved data to better understand the dynamics of weather-based displacement.
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.
Displacement Maps defines populations as displaced if they reside at least two kilometers (roughly 1.2 miles) away from their pre-crisis home, and if the distance traveled away from their pre-crisis home location has doubled. Never displaced populations are those that don’t meet either of the aforementioned conditions, and unknown populations are Facebook users who haven’t connected at least three days in the two-week period post-crisis.
Facebook says that the improved Displacement Maps have been applied to Cyclone Fani in India and Bangladesh, where they have helped to show that areas like Bhubaneswar experienced a 15% displacement compared with cities near the Kolkata area, which experienced only 1% to 2% displacement. Applied to Typhoon Hagibis, which hit Japan in October 2019, Displacement Maps revealed large numbers of people leaving the Tokyo area.