MobileActive.org

After a disaster or humanitarian crisis, people often leave affected areas and resettle elsewhere. These population shifts can strain infrastructure and make it difficult to coordinate relief efforts when no one knows exactly where displaced individuals have gone. After the January 2010 earthquake in Haiti, more than one million Haitians were left homeless; in the ensuing months the country was hit by a cholera outbreak that has now killed roughly 7000 people. Two years after the earthquake, there are still nearly 500,000 people living in displacement camps across the country.

Haiti’s population movements, combined with the cholera outbreaks, highlight the importance of identifying areas where infrastructure is strained after disasters. In response, a recent research paper "Improved Response to Disasters and Outbreaks by Tracking Population Movements with Mobile Phone Network Data: A Post-Earthquake Geospatial Study in Haiti" examines how SIM card data can be used to draw conclusions about post-disaster population movements.

The researchers behind the study partnered with the Haitian mobile operator Digicel to collect information on SIM card locations. Using geographic positioning from mobile towers, the researchers analyzed data from 1.9 million SIM cards from December 1, 2009 to June 18, 2010. Dr. Linus Bengtsson, a lead researcher on the original paper, explains that the value of using mobile data is that it can be analyzed rapidly to privde a more clear picture of population shifts.

He notes, for instance, that cholera outbreaks spread quickly as the disease thrives in environments with overcrowding, poor sanitation, and a lack of clean drinking water made worse by natural disasters. Using mobile phone location data to understand and predict where populations are resettling could allow relief workers to directly target high-risk areas, conserving resources and time.

Bengtsson is now co-founding a non-profit organization called Flowminder to replicate the use of mobile location tracking in disaster and humanitarian relief efforts. According to Bengtsson, the aim of Flowminder is to be an independent resource for population data.  

He explains,

"Many [mobile] operators are reluctant to give data to other commercial entities because it has a big commercial value, and many operators are reluctant to give it to governments as well. So that prompted us to become an independent clearinghouse based in Sweden - to be able to do these kind of analyses and provide this information rapidly in disasters."

Key Findings from the Original Research and Going Forward with Flowminder

Mobile phones, when turned on, connect to a series of local cell towers, ensuring that calls or SMS aren’t dropped. A mobile phone’s location can be roughly determined by analyzing the cells it is connected to, as the towers reveal when and where the phone is in use. In turn, SIM cards contain the user’s unique subscription information. Combining the SIM card information with the towers it connects to reveals approximately where a mobile phone has been in use. "Improved Response to Disasters and Outbreaks by Tracking Population Movements with Mobile Phone Network Data: A Post-Earthquake Geospatial Study in Haiti" uses this data to draw conclusions about the Haitian population's response to the earthquake.

Because the earthquake occurred on January 12th, the location data included where people had spent New Year's Eve and Christmas. According to Bengtsson, this information was valuable. He says, "What we see is that after the disaster, [Haitians] returned to places where they were at Christmas and New Year's. People presumably go to places where they have strong social bonds; family or people that can support them in difficult situations." Bengtsson says Flowminder hopes to predict earlier where people will go after disasters so that relief workers can directly target those areas for aid.

The speed of information analysis was also a key finding of the report; while traditional population monitoring requires workers to conduct time-consuming, in-person surveys, mobile data can be collected, analyzed, and disseminated almost immediately. The report states:

We additionally illustrate that it was feasible to produce and disseminate data on movements of SIM cards from an area with an infectious disease outbreak within hours of receiving the data. These results suggest that the speed and accuracy of estimates of population movements during disasters and infectious disease outbreaks may be revolutionized in areas with high mobile phone coverage.

Despite the potential for the project for targeting relief efforts, mobile location tracking is controversial as it brings up significant questions of privacy, confidentiality, and inclusiveness. Bengtsson stressed that Flowminder has important work ahead in continuing research on how to ensure that mobile phone tracking is inclusive, as vulnerable groups like women, children, and the elderly are less likely to have access to mobile phones than adult men.

Privacy is also a main concern for Flowminder and Bengtsson says the work in Haiti focused on using non-identifying information.  He says, "... in Haiti, we asked the provider Digicel to provide data that was anonymized before we analyzed it. And the analysis that we provided to relief organizations was aggregated data where you could not see individuals." Going forward, he says that all information will be anonymized (no SIM card identifications or phone numbers), and will be released as aggregated data so that individual movements can't be determined.

The results from the SIM card data returned results that were very similar to a large-scale UN study.  Mobile data can deliver near real-time information on populations after a disaster, targeting relief information.  

Editor's Note: According to the researchers, the use of mobile location data was anonymised with Digicel providing no IMSI information but non-identifiable information about 2.8 million SIMs. The researchers narrowed that dataset down to SIMs that had made a call within a certain window before and after the earthquake. Bengtsson said during the interview that the team will only accept anonymized data, and that they will only release it as aggregate information to document large population movements so that people can't be identified.