LAUSR

Union estimates that 92% of the global population, including 89% of people in Least Developed Countries (LDCs), have mobile network coverage with 105 mobile-cellular telephone subscriptions per 100 people globally, and 74 subscriptions per 100 people in LDCs.5 However, mobile device penetration remains substantially lower in many vulnerable populations. CDRs are routinely produced by MNOs for billing purposes each time a subscriber makes or receives a call, sends or receives a text message, or uses mobile data (“network events”). Each record contains the time of the event and and Vanuatu.6 It has a range of applications in disaster management, including dynamic population mapping and calculating flows between locations. These indicators reveal important information throughout a disaster, such as the number of people who may be affected by a disaster, the number complying with evacuation orders, the origins, and destinations of internally displaced people (IDPs), and the return of IDPs to their pre-disaster residence (see Figure 2). Flowminder’s analysis of three disasters in Haiti and Nepal,2 and confirmed for other disasters,13 has shown a consistent decay rate in the the cell site it was routed through, thereby describing subscribers’ movements. By pseudonymizing and aggregating CDR data over large numbers of subscribers, practitioners produce mobility indicators that provide insights into the overall movement of the population while preserving individual privacy. Furthermore, because this data is collected in near-real time, indicators can be calculated within days to aid the response to ongoing crises. CDRs have been used to support responses to natural disasters in Low-to-Middle Income Countries (LMICs), including Bangladesh,8 Haiti1,7 (see Figure 1), Nepal12 S EVERE DISASTERS CAN cause large population movements as affected people are displaced from their residences. The humanitarian response to such events relies on understanding where affected people are located. Mobility data can provide important insights at all stages of a crisis, from preparedness to longterm recovery. At Flowminder, a nonprofit foundation based in Sweden, the U.K., and Switzerland, we are working to support decision-makers to transform the lives of vulnerable people by facilitating access to novel sources of mobility data, including Call Detail Records (CDRs). Across Europe, non-profits, national statistical services, academic institutions, and mobile network operators (MNOs), including Orange, Telefonica, Telenor, and Vodafone, are collaborating on using CDR to support public policy. Additionally, the European Commission established the High-Level Expert Group on Businessto-Government Data Sharing to support such collaborations, including in response to the COVID-19 pandemic.9 The global spread of mobile devices provides new opportunities for better understanding mobility and addressing mobility data gaps. The International Telecommunication Mobile Phone Usage Data for Disaster Response