World Tsunami Awareness Day: Tsunami Preparedness for Hawaiʻi and Pacific Island Communities

What is World Tsunami Awareness Day?

In December 2015, the UN General Assembly designated Nov. 5 as World Tsunami Awareness Day. The idea came from Japan, and the UN Office for Disaster Risk Reduction (UNDRR) facilitates the observance (United Nations).

The UN's case for the day is that tsunamis are rare but very deadly. In the past 100 years, 58 tsunamis have killed more than 260,000 people, an average of 4,600 per disaster, more than any other natural hazard (United Nations). Because they are rare, people forget what to do. The UN's key messages stress drills, evacuation mapping, risk education and sustained awareness that “maintains tsunami risk memory” (United Nations). Its #GetToHighGround campaign, launched in 2022, encourages communities to walk or run their evacuation routes (United Nations).

Why does this matter so much in Hawaiʻi and the Pacific?

Hawaiʻi's warning system was built after a disaster. On April 1, 1946, a tsunami from an Aleutian earthquake killed 159 people across the state, 96 of them in Hilo within two hours. The earthquake was recorded at 2:06 a.m. Hawaiʻi time but not noticed until staff arrived at 7:30 a.m., after the waves had started hitting Hilo. Congress responded by funding the Seismic Sea Wave Warning System, operational in 1949 and now the Pacific Tsunami Warning Center (PTWC) (USGS Hawaiian Volcano Observatory).

Honolulu's Department of Emergency Management (DEM) says more than 220 people have died in Hawaiʻi from tsunamis since 1946, including six on Oʻahu, and some locations have flooded to depths of more than 30 feet (Honolulu DEM). PTWC is the warning center for Hawaiʻi, American Samoa, Guam and the Northern Mariana Islands, and the operational headquarters of the Pacific Tsunami Warning System, which advises national authorities across the basin (International Tsunami Information Center).

The Pacific also shows how little time a local event can leave. When Hunga Tonga-Hunga Haʻapai erupted on Jan. 15, 2022, a tsunami was observed locally within minutes. It damaged buildings and caused four deaths in Tonga, and a later field survey found a maximum tsunami height on land of about 22 meters (72 feet) on Tofua Island (NOAA NCEI).

Local and distant tsunamis: how much warning will you get?

Honolulu DEM describes two kinds of tsunami threat (Honolulu DEM):

• Local tsunami: waves can arrive on Oʻahu in as little as 30 minutes. An earthquake on or near Hawaiʻi Island is the most likely cause. There may be no time for an official alert, so natural signs are the warning.
• Distant tsunami: travel time can be as short as five hours from Alaska or as long as 14 hours from Chile. That gives time for official warnings, and also time for traffic to build.

Natural warning signs include strong shaking, the ocean acting strangely (a fast-rising flood, a wall of water, or water draining away to expose the sea floor) and a roar from the sea. If you notice them near the coast, DEM says to move to higher ground right away without waiting for an official message (Honolulu DEM). Tsunami waves can keep arriving for hours, and the first wave may not be the largest (Honolulu DEM; United Nations).

What do the four tsunami alert levels mean?

In Hawaiʻi, tsunami alerts come from PTWC. The U.S. warning centers use four levels, each tied to a public action (U.S. Tsunami Warning Centers; Honolulu DEM):

A cancellation is not the same as an all-clear. It means water-level data show a destructive tsunami will not reach the area or has diminished; local officials still decide when it's safe to return to the coast (Honolulu DEM).

What did the July 2025 Kamchatka warning teach Hawaiʻi?

Honolulu's after-action report calls the timing one of the worst cases for evacuation management: a workday, shortly before rush hour, with about five hours of warning. Despite major congestion, the primary tsunami evacuation zone was cleared by the anticipated impact time, and there were no reported evacuation-related fatalities (Honolulu DEM after-action report; City and County of Honolulu, July 10, 2026).

The report also documents what went wrong. Only the primary zone was ordered to evacuate, but initial findings from a state Department of Transportation traffic study showed that 92% of vehicle trips on Oʻahu were unnecessary, because many people left safe areas or went farther than needed. The report adds that vertical evacuation was not widely understood, particularly in urban Honolulu, and that extended care facilities and medically fragile residents lacked individual evacuation plans, which flooded 911 and ambulance providers with calls (Honolulu DEM after-action report).

Two capacity issues stand out for island emergency management. DEM had 15.5 positions at the time of the warning; it has since received funding for 13 more (Hawaiʻi Public Radio, July 16, 2026). And in August 2025, about 340 of the state's 400 outdoor sirens were operational, according to the HI-EMA dashboard cited by Hawaiʻi Public Radio, with 11 beyond repair (Hawaiʻi Public Radio, Aug. 29, 2025).

Know your zone: primary, extreme and vertical evacuation

Oʻahu has two mapped zones. The Primary Tsunami Evacuation Zone (red) is used for most warnings. The Extreme Tsunami Evacuation Zone (yellow) applies only if officials issue an Extreme Tsunami Warning, for example after a magnitude 9.0 or larger earthquake in the eastern Aleutian Islands (Honolulu DEM). You can check an address in the Oʻahu Hazard Explorer linked from DEM's tsunami page.

• If you're in the zone, leave as soon as a warning is issued, and walk if you can, because traffic may be heavy (Honolulu DEM).
• If you can't get out in time, vertical evacuation is an option: go to the fourth floor or higher of a building that is 10 stories or taller (Honolulu DEM).
• If you're not in the zone, stay home and stay off the roads so evacuees and first responders can move (Honolulu DEM).
• Boaters should move vessels to at least 50 fathoms (300 feet) of water and 2 miles from harbor entrances, following the Captain of the Port; everyone should stay at least 100 feet from inland waterways connected to the ocean (State of Hawaiʻi GIS notes).
• Remember the limits of the maps. The state's notes say the evacuation maps don't account for a locally generated tsunami: if you feel shaking, move inland immediately (State of Hawaiʻi GIS notes).

Hawaiʻi's outdoor sirens and the Emergency Alert System are tested on the first business day of each month; the October 2026 test was at 11:45 a.m. (HI-EMA; Office of the Governor). If you hear a siren at any other time, tune in to local radio, TV or official channels, and watch for Wireless Emergency Alerts on your phone (HI-EMA).

A household checklist before Nov. 5

DEM's preparedness guidance fits on one page (Honolulu DEM):

• Look up your home, work and school addresses in the evacuation zone map.
• Make a family plan with a meeting place and an off-island contact everyone knows.
• Plan for keiki, kūpuna, pets and anyone who relies on powered medical devices.
• Pack a go bag for each person, and build a 14-day disaster supply kit.
• Learn the natural warning signs, and check what your insurance covers.

Walking your route once, as the UN's #GetToHighGround campaign suggests, is the fastest way to find out whether your plan works (United Nations).

What should island governments and organizations do?

In ISPI's analysis, the 2025 warning confirms that the technical warning works and that the weak points are the last mile: how people understand alerts and how they move. ISPI's CM-09: Tsunami Preparedness in Pacific Island Communities argues for multilingual warnings, noting that many Hawaiʻi residents speak languages such as Ilocano, Chuukese and Marshallese at home, and for evacuation route analysis that assumes roads may be damaged after an earthquake.

• Teach the two zones and vertical evacuation in plain language and in the languages people speak at home.
• Require evacuation plans from care facilities, as Honolulu's report recommends, so 911 capacity is left for people with no other option.
• Keep alerting redundant. Sirens, phone alerts, broadcast and door-to-door contact each reach different people, so maintenance backlogs matter.
• Script the first hour for employers and agencies, so releasing staff doesn't put people outside the zone on the roads at once.

For broader planning frameworks, see WP-03: Island Emergency Management Framework, which recommends multi-hazard mass notification with redundant, independent channels, PB-11: Hurricane Emergency Management in Pacific Island Communities on compound emergencies, and HI-08: Climate Resilience and Emergency Policy. Related analysis: Typhoon Bavi and island warning systems in the CNMI and Red Hill and island water security.

Frequently asked questions

When is World Tsunami Awareness Day?

Nov. 5 each year. The UN General Assembly designated the day in December 2015 (United Nations).

How much warning would Oʻahu get before a tsunami?

For a local tsunami, as little as 30 minutes; for a distant one, about five hours from Alaska to 14 hours from Chile (Honolulu DEM).

Do I have to evacuate the yellow zone in every tsunami warning?

No. Most warnings require leaving only the primary (red) zone. The extreme (yellow) zone is evacuated only under an Extreme Tsunami Warning (Honolulu DEM).

What is vertical evacuation?

If you can't leave the zone quickly, go to the fourth floor or higher of a building with 10 or more stories (Honolulu DEM).

When are Hawaiʻi’s tsunami sirens tested?

On the first business day of each month, together with the Emergency Alert System (HI-EMA).

ISPI publishes its research free under CC BY 4.0. If your agency, island government or organization needs a tsunami or multi-hazard preparedness review, evacuation planning analysis or a policy brief, you can commission research from ISPI. ISPI is a nonprofit organization; its application for 501(c)(3) tax-exempt status is pending. Contributions are not tax-deductible until IRS recognition is granted.

Sources

1. United Nations, “World Tsunami Awareness Day, 5 November”
2. USGS Hawaiian Volcano Observatory, “Volcano Watch — HVO’s role in the history of tsunami prediction in Hawaii”
3. International Tsunami Information Center (UNESCO/IOC–NOAA), “PTWC, JMA, US NTWC”
4. NOAA National Centers for Environmental Information, “January 15, 2022 Tonga Volcanic Eruption and Tsunami”
5. City and County of Honolulu Department of Emergency Management, “Tsunami”
6. U.S. Tsunami Warning Centers (NOAA/NWS), “Tsunami Message Definitions”
7. NWS Pacific Tsunami Warning Center, Hawaiʻi tsunami messages for the July 29, 2025 Kamchatka earthquake: No. 1, No. 3, No. 10, No. 20
8. City and County of Honolulu Department of Emergency Management, “Tsunami Warning After Action Report, July 29–30, 2025”
9. Office of the Mayor, City and County of Honolulu, “City and County of Honolulu releases Tsunami Warning After Action Report,” July 10, 2026
10. Savannah Harriman-Pote, “New report lays out highs and lows of Honolulu tsunami response,” Hawaiʻi Public Radio, July 16, 2026
11. Ashley Mizuo, “Traffic jams and broken sirens: Officials reflect on lessons learned from tsunami warning,” Hawaiʻi Public Radio, Aug. 29, 2025
12. Hawaiʻi Emergency Management Agency, “All-Hazard Statewide Outdoor Warning Siren System”
13. Office of the Governor, “Monthly Siren and Emergency Alert System Test for October 2026,” Sept. 29, 2026
14. State of Hawaiʻi Office of Planning GIS Program, “Tsunami and Extreme Tsunami Evacuation Zone Maps — Cautions and Additional Information”
15. ISPI papers: CM-09, WP-03, PB-11, HI-08