EASs

Emergency Alert Systems (EASs) are national public warning systems used to provide critical information to the population during emergencies. In the United States, the EAS was established in 1995 under the Homeland Security Act and is managed by the Federal Emergency Management Agency (FEMA) in partnership with the Federal Communications Commission (FCC). Its purpose is to broadcast timely warnings about natural disasters, severe weather, and other events that could pose a threat to public safety.

EASs operate through a network of broadcasters, cable and satellite providers, radio stations, and digital services. When an alert is issued, the federal government or designated state, region, or local authorities transmit a pre‑recorded message that supersedes all other programming. The system uses the Common Alerting Protocol (CAP) format to encode information such as the event type, affected area, and recommended actions.

The EAS also supports the Emergency Alert System Test, a biannual assessment that checks the entire chain of alert delivery. During these tests, a simulated emergency message is broadcast to confirm that equipment, protocols, and personnel are functioning correctly. Public participation is encouraged through the use of the Traffic and Hazard Information Source System (THISS), enabling critical information from local communities to be included.

EASs are considered a backbone of national resilience, enabling rapid dissemination of emergency information. Since their inception, they have been employed in major events such as tornado outbreaks, earthquakes, and tsunamis, helping to reduce loss of life and improve emergency response coordination.