*A decade of wireless emergency alerts: A longitudinal assessment of message content and completeness

Wireless Emergency Alerts (WEAs) provide a direct way for public safety officials to reach at-risk publics via text-based messages on their mobile devices. Although WEAs were introduced over a decade ago and can be either 90 or 360 characters in length, we currently do not know what these messages have contained. To address this gap, we quantify the contents of the last decade of WEA messages using the principles of effective warning message design. Specifically, we use quantitative content analysis to conduct a longitudinal assessment of 6,080 WEAs sent by Alerting Authorities (AAs) from 2012 to 2022. We code hese messages according to the concepts in the Warning Response Model (WRM; Mileti & Sorensen, 1990), which establishes that WEAs need to include information about the hazard, location, source, guidance, and time. Our results indicate that source and timing information are included at a much lower rate than location, hazard, and guidance information. Furthermore, only 8.5% of these messages are complete—or include all five pieces of WRM content. Complete WEA messages can minimize protective action delay while maximizing message understanding, belief, and personalization. We also find that 360-character WEAs are more likely to be complete than 90-character WEAs. Thus, those responsible for crafting WEAs should continue to take full advantage of the increased number of characters to write complete messages that warn populations at risk, rather than simply alert them to the existence of a hazard.