Geo-targeting Performance of Wireless Emergency Alerts in Imminent Threat Scenarios

A significant long-standing challenge for imminent threat alert originators (AOs) at all levels of government is how to quickly communicate warning messages to people in danger, while avoiding to warn those not at risk. Providing effective warnings of an imminent threat, such as a dangerous tornado, can save lives. Ideally, people can take shelter before the tornado strikes if they are provided enough warning time. People may receive irrelevant warnings and suffer from over-alerting, however. If over-alerting occurs, people's lives can be disrupted; they may decide the warnings they receive are not accurate and may ignore later warnings that actually apply to them. Several terms have been coined to describe the impact of over-alerting: warning fatigue or warning complacency. Warning fatigue has occurred in highly destructive and deadly tornadoes. People ignored warnings delivered by sirens because the sirens had sounded so many times on past occasions when no tornado appeared. The sirens have also been sounded over too large of an area in past tornadoes (over county-wide areas), and included areas where the public was not threatened. How can over-alerting and warning fatigue be reduced? One possible solution is to send tornado warnings as accurately geo-targeted Wireless Emergency Alerts (WEAs). This study shows that overalerting rates can be reduced if the geo-targeting capabilities of WEA are used effectively.