A preliminary assessment of WEAs issued for the July 29, 2025 Tsunami
- jeannettesutton
- 2 days ago
- 6 min read
This is a long post that includes a LOT of WEAs (14 to be exact). Because I followed the December 5, 2024 tsunami event fairly closely, I was curious to see how this one would play out. In this case, multiple states received a Tsunami Warning from NWS-Pacific Tsunami Warning Center (portions of CA and AK; and all of HI), and Tsunami Advisories were issued by counties for their coastlines. Hawaii issued 4 Wireless Emergency Alerts; four counties in California issued Tsunami Advisory messages. In the paragraphs that follow, I point to key factors in each message known to affect message understanding and ability to take action.
The NWS Pacific Tsunami Warning Center issued 3 Tsunami Warning WEAs – 1) to Hawaii, 2) Northern Humboldt Coast; Coastal Del Norte, 3) Central Aleutians; Pribilof Islands; Western Aleutians, Alaska. Because NWS Tsunami messages are pre-scripted, all three contained the same contents: “The National Weather Service has issued a TSUNAMI WARNING. A series of powerful waves and strong currents may impact coasts near you. You are in danger. Get away from coastal waters. Move to high ground or inland now. Keep away from the coast until local officials say it is safe to return.” None of the NWS messages include the specific names of locations at greatest risk or those that need to take action (this is common to all NWS WEAs).
Hawaii issued 4 WEAs. The first (188 characters) was purely a notification to alert the public that sirens would be sounding in advance of the predicted wave arrival time. There was no source included in the message and no specific instructions about what to do/how to prepare or where to go for additional information.
The 3 Hawaii WEAs that followed were written in ALL CAPS (with the exception of the name of the sender, which was placed at the end of the message). Each WEA (155 characters) said the same thing: sirens sounding for tsunami threat. [#] hrs out from 1st wave arrival estimated at 7:10 PM HST. Evacuate coastal areas. Sent by Hawaii Emergency Management Agency.
90-character WEAs were similar, presented in ALL CAPS, but did not include a countdown of hours or minutes for the wave arrival.
Interestingly, the instruction field (not pictured) included a great deal of additional information about the tone that would be sounded through the outdoor warning sirens; this will be visible only to those with iPhones. The message also instructed the public to evacuate in an orderly fashion, to comply with officials, and to monitor local media.
Given that each HIEMA WEA used far fewer characters than the allowable 360, additional information could have been provided about where to get information, how far to travel away from coastal areas, where an evacuation center may have been established, who to contact for assistance evacuating, and even how to evacuate vertically if a person was unable to leave. Instructions about what to bring along would also be useful information, especially given the multiple hours of advanced notice that was provided.
While there were no additional WEAs issued by the Humboldt/Del Norte areas in CA (under Tsunami Warning), a number of California Counties that were under a Tsunami Advisory did issue alerts. For example, San Luis Obispo County Fire employed the language of “Evacuation Warning” to notify people about a Tsunami Advisory in their county. If you are familiar with wildfire language, you know that “Evacuation Warning” and “Evacuation Order” are the terms required by CalOES, put into practice following wildfires in 2018.
The success of evacuation warning and order messages are dependent upon the message receiver knowing the difference between the two terms and recognizing that they represent two different phases of action – warning means, generally, “prepare to leave” and “order” means leave now. In this case, people receiving the evacuation warning message were to prepare to leave, which seems to correspond with the potential impacts associated with a Tsunami Advisory. Researchers have found that warning and order are not well known among the public; both are normally interpreted to mean "leave now."
One other note about the SLO WEA - Most of the message characters were dedicated to listing the zones that were under the evacuation warning and describing those zones using plain language. The 90-character message listed zones only, with no plain language explanation. People were also directed to a webpage for additional information; no timing information was included.
The use of technical language in the SLO County Fire message suggests they have high expectations from the population receiving this message: expectations that message receivers understand the impacts associated with a Tsunami Advisory; the difference between an evacuation warning and order and the associated protective actions; and the zones that are under those orders.
LA County OEM issued three WEAs for three different areas. Each included the message source “LA County OEM” and the words “Tsunami Advisory” with a description of the area of impact (beaches, ports, and low-lying areas near the coast of Los Angeles County). They also indicated the start -time of the advisory (starting around 1 am) and provided a statement about the impacts associated with an advisory (strong currents and dangerous waves expected; could be life threatening and damage watercraft and structures). Protective action instructions were stated in ALL CAPS “STAY OUT OF WATER, AWAY FROM BEACHES AND WATERWAYS.” And a URL was provided for more information.
Sonoma County Sheriff issued one WEA, indicating that a Tsunami Advisory is in effect for the Sonoma Coast UNTIL 3:30am. The message included potential hazard impacts (dangerous currents and waves possible) and instructions to STAY OFF BEACHES, out of the water, and AWAY from harbors and marinas. They also instructed people not to go to the coast to watch the tsunami and to only call 911 for life-threatening emergencies. A website and phone number were provided for more information. Throughout the message, they selectively used ALL CAPS to highlight key words and to make it easier to read.
And rounding out the list, the City of Long Beach also issued a WEA. In this case, the alert indicates that a Tsunami Advisory had been issued for the CA coast (by the NWS) on 7/29/25 at 6:27pm. The message reinforced that the public should stay out of the water and away from beaches and waterways. They also provide the estimated time of tsunami arrival, according to the National Tsunami Warning Center. A URL is provided for more information.
In each message that includes a link to more information, they provide a web address that is branded with the organization name at .org or .gov, which should increase trust in the link. Notably across messages that include time information, we see variation in the way it is used - such as as the time when the advisory was issued, the time when impacts were expected, and the time the advisory went into effect.
We know from decades of research what information should be contained in a warning to reduce delayed action; we also know from ongoing studies how to structure a message to be most meaningful to message receivers (including the order of contents and the use of CAPS in a message). We have studied the importance of using plain language that is unambiguous and how technical language can cause confusion.
Importantly, while we have limited research focused on tsunami WEAs and public response to them, we know that this is an unfamiliar threat made difficult to understand partly due to lack of experience and also the technically challenging language used by NOAA to describe watch, advisory, and warning stages. Without a clear strategy from local authorities to not only amplify the message from NWS but to also clarify its meaning, the public will be left to interpret the dangers on their own.
For more recommended contents, be sure to download The Warning Lexicon - it's free and offers step-by-step instructions on how to write a better warning message.
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