Upon receipt of tsunami watches and warnings, coastal National Weather Service (NWS) offices such as those in Seattle and Portland, activate the Emergency Alert System (EAS) via NOAA Weather Radio. All broadcasters (TV, AM/FM radio, cable TV) receive the tsunami EAS message simultaneously as well as those with weather radio receivers in homes, businesses, schools, health care facilities, etc. NOAA Weather Radio also activates the All-Hazard Alert Broadcast (AHAB) units located in remote coastal areas, alerting people in those isolated locations.
Upon receipt of tsunami watch and warning messages, local emergency management officials (see Clallam County, WA as an example) can decide to activate the Emergency Alert System (EAS) to evacuate low-lying coastal areas in advance of the initial tsunami wave. Their EAS messages are also received by broadcasters, weather radio receivers and All Hazard Alert Broadcasts (AHABs) to help provide widespread dissemination of these messages. Follow the directions provided by your area emergency management officials - they will help save your life and those of your loved ones.
If you want your own tsunami warning message receipt system, obtain a NOAA weather radio receiver with EAS-programmable features. They are available from most radio electronic retailers and on the Internet.