When disasters strike, people flee. In the wake of earthquakes, floods, and hurricanes, relief organizations spring into action and dispatch people and resources to affected areas. But where do they go to find the people who have fled and need help? Today, relief workers rely on aerial surveys, eyewitness accounts, or manual headcounts at shelters to estimate where people affected by the event have moved. But it takes a while for people to be tracked down, and often, the techniques are not comprehensive.
A new way of tracking people using cell phone data from the moments before the disaster could help target appropriate relief efforts at the right locations, in the crucial 12 hours after an event. "Affected people often move—and it becomes very difficult to deliver the right amount of supplies to the right places," Linus Bengtsson, one of the creators of the method, told Fast Company. "This method could be very good for alleviating this problem."
As long as their towers stay up, cell phone companies continue to register everyone making calls on their phones. That's data that they collect routinely. Bengtsson and his colleagues at Sweden's Karolinska Intitutet and Columbia University have come up with a way to quickly and reliably mine that data and use it to estimate how people are moving.
Bengtsson and his co-authors worked with the Haitian cell phone service provider Digicel in the months following the country's devastating earthquake. They used data from 282 million calls from 2.8 million phones, from six weeks before the disaster to five months after it, to develop a system that would quickly extract location information from Digicel's records. The data is fully anonymous, but it does show where people are moving to and from.
In a study published yesterday, they show the migration patterns of people after the earthquake—patterns that match up with a thorough UN-led study that took place in the months following. It showed that 600,000 people had fled Port-au-Prince for the countryside, but soon returned. Information like this would have allowed aid workers to follow them inland to provide the necessary services.
There was a chance to test the new technique when a cholera epidemic swept through the country earlier this year. With links to Digicel already in place, it didn't take the group long to spring into action. "At the immediate start of the outbreak, we got data from the mobile phone company, and within 12 hours, we had distributed reports about where people were moving to relief agencies," said Bengtsson.
It's too soon to say if the data the group gave relief organizations changed the way they worked, but Bengtsson is enthusiastic about the potential of the new technique. Tellingly, the groups' commitment to the project goes beyond this one study. "We’re now setting up a non-profit organization to globally carry out this type of analyses on a routine basis during future disasters," Bengtsson said.
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[Image: Flickr user IFRC]