The National Weather Service in Honolulu says many people are wondering why their cell phones did not alert them to a tsunami watch.
At 11:32 p.m. HST Monday, a magnitude 7.9 earthquake struck off Alaska, approximately 174 miles southeast of Kodiak.
Eleven minutes later, at 11:43 p.m. HST, the Pacific Tsunami Warning Center issued a tsunami watch for Hawaii.
“A tsunami watch is issued to alert emergency management officials and the public of an event which may later impact the watch area. The watch area may be upgraded to a warning or canceled based on updated information and analysis.” – ptwc.weather.gov
The PTWC canceled the watch at 1:10 a.m. HST Tuesday after data indicated no tsunami threat to Hawaii.Related Story: Tsunami watch canceled for Hawaii after M7.9 earthquake strikes off Alaska
Due to the late hour, many in Hawaii didn’t realize a watch was even issued until later Tuesday morning.
As we explained previously, the National Weather Service sends out alerts that residents get on their TVs, radios, as well as their cell phones.Related Story: National Weather Service explains how its alert system works
So why wasn’t there a tsunami watch alert? Officials offer the following explanation:
Wireless Emergency Alerts (WEA) are emergency messages sent by authorized government alerting authorities through your mobile carrier.
Government partners include local and state public safety agencies, FEMA, the FCC, the Department of Homeland Security, and the National Weather Service.
Alerts are sent automatically to WEA-capable phones during an emergency.
As of January 2018, only the following most urgent National Weather Service warnings are sent nationwide as WEA messages:
- Tsunami Warnings
- Tornado Warnings
- Flash Flood Warnings
- Hurricane Warnings
- Typhoon Warnings
- Dust Storm Warnings
- Extreme Wind Warnings
These notifications are meant to help people understand that a real threat is coming.
In order to minimize disruption to wireless device users, watches, advisories and other types of warnings are not disseminated via WEA and will not alert your phone.
There are different levels of tsunami threats: watch, advisory, and warning.
A tsunami watch mean there is a potential threat but not dangerous enough to worry the public just yet. Experts want to analyze the earthquake data and sea level readings first before sending out any public messages.
“When we put Hawaii in an advisory, it just means cease all activities along the beaches. It just means get people out of the water,” said Stuart Weinstein with the PTWC. “The warning means there’s an inundation threat, that the tsunami could invade the land to a certain extent, and that could cause other problems, so at that point, we would evacuate Hawaii’s coastlines.”
KHON2 sent out alerts for both the tsunami watch and subsequent cancellation via our own news app.
Many warnings and watches are also tone-alerted via NOAA Weather Radio.Click here for more information on Wireless Emergency Alerts.(weather.gov)Click here for more information on NOAA Weather Radio.(noaa.gov)
The U.S. Tsunami Warning Centers issue tsunami messages to notify emergency managers, the public, and other partners about the potential for a tsunami following a possible tsunami-generating event. To provide messages as early as possible, the warning centers use preset criteria based on preliminary earthquake information (Atlantic, Pacific), before a tsunami is detected, to help them decide when and for where to issue tsunami messages and what alert(s) to include. Subsequent messages and alerts are based on impact estimation resulting from additional seismic analysis, water-level measurements, tsunami forecast model results, and historical tsunami information.Domestic Tsunami Messages
Domestic tsunami messages are issued for U.S. and Canadian coastlines and the British Virgin Islands. These messages include alerts and also serve to cancel alerts, when appropriate. There are four levels of tsunami alerts: warning, advisory, watch, and information statement. Each has a distinct meaning relating to local emergency response. Recommended protective actions vary within areas under warnings and advisories. Be alert to and follow instructions from local emergency officials because they may have more detailed or specific information.
|Alert Level||Potential Hazard(s)||Action|
|Dangerous coastal flooding and powerful currents||Move to high ground or inland|
|Strong currents and waves dangerous to those in or very near water||Stay out of water, away from beaches and waterways|
|Not yet known||Stay tuned for more information|
Be prepared to act
|No threat or very distant event for which hazard has not been determined||No action suggested at this time|
Tsunami Warning – A tsunami warning is issued when a tsunami with the potential to generate widespread inundation is imminent, expected, or occurring. Warnings alert the public that dangerous coastal flooding accompanied by powerful currents is possible and may continue for several hours after initial arrival. Warnings alert emergency management officials to take action for the entire tsunami hazard zone. Appropriate actions to be taken by local officials may include the evacuation of low-lying coastal areas, and the repositioning of ships to deep waters when there is time to safely do so. Warnings may be updated, adjusted geographically, downgraded, or canceled based on updated information and analysis.
Tsunami Advisory – A tsunami advisory is issued when a tsunami with the potential to generate strong currents or waves dangerous to those in or very near the water is imminent, expected, or occurring. The threat may continue for several hours after initial arrival, but significant inundation is not expected for areas under an advisory. Appropriate actions to be taken by local officials may include closing beaches, evacuating harbors and marinas, and the repositioning of ships to deep waters when there is time to safely do so. Advisories may be updated, adjusted geographically, upgraded to a warning, or cancelled based on updated information and analysis.
Tsunami Watch – A tsunami watch is issued when a tsunami may later impact the watch area. The watch may be upgraded to a warning or advisory or canceled based on updated information and analysis. Emergency management officials and the public should prepare to take action.
Tsunami Information Statement – A tsunami information statement is issued when an earthquake or tsunami has occurred of interest to the message recipients. In most cases, information statements are issued to indicate there is no threat of a destructive basin-wide tsunami and to prevent unnecessary evacuations. Information statements for distant events requiring evaluation may be upgraded to a warning, advisory, or watch based on updated information and analysis.
A cancellation is issued after an evaluation of water-level data confirms that a destructive tsunami will not impact an area under a warning, advisory, or watch or that a tsunami has diminished to a level where additional damage is not expected.