Geography Compass 8/1 (2014): 49–62, 10.1111/gec3.12104 No-Notice Urban Evacuations: Using Crowdsourced Mobile Data to Minimize Risk Christopher Edward Oxendine * and Nigel Waters Department of Geography and GeoInformation Science, George Mason University Abstract Emergency evacuations during the past decade have transitioned from landline analog to mobile digital communication devices. Over 88% of US citizens own a mobile phone, providing a tool to enable better communication between first responders and citizens in order to minimize risk to evacuees during no-notice evacuations. During an emergency, evacuees rely on social media to communicate with family, friends, and coworkers, often finding accessibility to social media more reliable than trying to make a phone call. Federal, state, and local emergency operations centers have made limited use of social media or Internet-based communications to provide an alternative means for citizens to request assistance or provide information. Mobile devices provide an alternative method of incident reporting and analysis through volunteered geographic information (VGI), which first responders can use to minimize risk to evacuees. 1. Introduction On September 11, 2001, America was shaken by the terrorist attacks at the World Trade Center in New York City, the Pentagon in Washington, D.C., and the crash of United Flight 93 in Shanksville, Pennsylvania. Thousands of Americans and over 370 foreign citizens perished from the attacks, and over 1 million evacuated from Manhattan (Kean 2004; Wikipedia 2012; de Wind 2012). Since then, major attacks have occurred in other metropol- itan areas around the world, including Madrid in 2004, London in 2005, Mumbai in 2006 and 2008, Karachi in 2007, and Boston in 2013. During large-scale terrorist events, no-notice emergency evacuations usually occur in an unorganized fashion. Individuals near the periphery of terrorist events desire to find the quickest and safest route to their home or somewhere they will feel safe. Of evacuees from the World Trade Center, 28% didn’t know where to go, and 12.9% reported that they didn’t know how to get to their destination (Zimmerman and Sherman 2011). These individuals rely on their knowledge of the surrounding area and public reporting through news media, emergency services, and social media to inform them of the hazards they may face in the area. Other no-notice events (e.g. tsunamis, chemical spills, and nuclear reactor meltdowns) also place citizens in situations where they have limited information and need to decide to evacuate or not. Deciding to evacuate and choosing the wrong route to travel to their home or another safe destination can place them at increased risk. Evacuees typically rely on prior knowledge of the area or use a mobile phone with assisted GPS or an Internet mapping service (e.g. Apple or Google maps) to find directions to their final destination. The resulting directions provide them with the shortest or quickest route; however, these directions often fail to account for the risk they may encounter along the route. Former US Homeland Security Secretary Michael Chertoff’s comments to students and faculty at George Washington University emphasized the importance of understanding and living with risk: © 2014 The Author(s) Geography Compass © 2014 John Wiley & Sons Ltd