Understanding tsunami warning signs


The role of Washington State Emergency Management is to help residents and visitors prepare for and respond to disasters such as tsunamis. Another role is to issue official warnings. This is done through the emergency alert system and the all-hazard alert broadcast (AHAB) siren system that’s located along the outer coast. Residents and visitors to Washington State need to be prepared to react and respond to different types of warnings that would be issued. For example, during a local Cascadia Subduction Zone event, there will be natural warning signs: The ground will shake; water may recede from the shoreline. They may be your only warning. In those instances, you need to be prepared to move inland or to high ground immediately. From a distant event such as one that would occur in Alaska or Japan, there will be more time to issue official warnings. Warnings would be issued through the emergency alert system, NOAA weather radio, and Washington State’s All Hazard Alert Broadcast (AHAB) sirens. These sirens will produce an official warning tone that alerts those outdoors to evacuate and move inland or to high ground immediately. Here at the Washington State Alert and Warning Center, tsunamis are one of the hazards we are concerned about. One of the first indicators of an earthquake or tsunami event will be from the California Integrated Seismic Network. We’ll usually get a visual and audio alarm as to where, when and the magnitude of the earthquake in question as one of our first indicators. Immediately following that, we’ll get two messages. One from the Washington State Patrol Access Messaging System. At the same time, we will also get a message from our email alert system. Once we receive our messages, we’ll get a call from the West Coast Alaska Tsunami Warning Center via the National Alert and Warning System (NAWS) phone circuit. [On phone: “This is the Washington warning point. Loud and clear.”] We have two phone circuits: the national circuit and the state circuit. The tsunami warning circuit will call us on the national circuit. We’ll respond to that. We’ll take down all the pertinent information. Immediately we will activate the state circuit and contact the counties that are most likely affected. These are either 4 costal counties and/or 14 inland counties. [On phone: “This is the Washington warning point. The preceding ring was for Clallam County, Jefferson County, Grays Harbor and Pacific county. Other stations disregard.”] Once the affected counties are notified via the National Alert and Warning System Network, we activate the alert and warning system message to alert the general population. From here, we can type the message, and send it out. It will go to various news agencies who will retransmit the message to television and radio. While the Emergency Alert System messages are transmitted from our duty positions, we have a backup system that has preselected messages we can use in case our primary system fails. One example of a tsunami message is already preloaded: “A tsunami warning has been issued for the coastal areas of Washington.” Once a tsunami warning message is received, one of the duty officers here at the Alert Warning Center will come to the AHAB (All Hazards Alert Broad system), and we’ll activate the sirens. Depending on what areas are affected, we have three preselected messages that we can transmit that will activate sirens on the coast.

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