On the first working day of every month, at 11:45 in the morning, roughly 400 sirens sound at once across our islands. Most of us barely look up. The keiki keep playing, the line at the lunch truck does not move, and the tone fades after about 50 seconds. That test exists because of specific mornings in our history when the ocean came ashore and kept coming, and because the people who lived through those mornings decided nobody else should be caught unaware.
We live here. Our kids go to school inside evacuation zones, and we have sat through a real warning with the car already packed. So this is what we want every visitor and every new neighbor to understand about tsunamis in Hawaiʻi: what has actually happened here, how you will be told, the signs nature gives you when there is no time for a siren, and exactly what to do. It is a short amount of knowledge, and it is the kind that saves families.
Related: Hawaiʻi Hurricane Season Preparation | Hawaiʻi Packing List | Best Time to Visit Hawaiʻi
Why are the sirens going off in Hawaiʻi right now?
If you landed here because you just heard the sirens, start with the calendar. Hawaiʻi tests its siren system on the first working day of every month at 11:45 in the morning, a steady tone for about 50 seconds. If it is the first workday of the month and it is late morning, that is the test and there is nothing to do.
If it is any other day, or any other time, treat it as real until you confirm otherwise. Turn on local radio or TV, check your phone for a Wireless Emergency Alert, and look outside. Here is the tell we grew up with: watch how people are moving. If traffic suddenly picks up and everyone is heading mauka, toward the mountains, if neighbors are loading kids into cars faster than normal, if you see police and fire rolling through with loudspeakers, that is your confirmation. You do not need to wait for someone to tell you officially. Get to higher ground and sort out the details when you are safe.
And if you felt strong shaking first, do not wait for a siren at all. Move now, and read the rest of this once you are up and inland.
Why our islands sit right in the path
Hawaiʻi sits near the center of the Pacific basin, ringed on nearly every side by the subduction zones people call the Ring of Fire. When the seafloor snaps off Alaska, Kamchatka, Japan, or Chile, the energy spreads outward like ripples in a pond, and our islands are one of the places those ripples converge. There is no continental shelf out here to soften the blow either. Deep water runs almost to our shoreline, so a wave can arrive with most of its energy intact.
More than 85 tsunamis have been recorded in Hawaiʻi since the early 1800s, and at least 15 of those caused real damage. In deep ocean a tsunami moves around 500 miles per hour (roughly 800 km/h), about the speed of a jetliner, and it is barely noticeable out there. It only becomes a monster when it reaches shallow water, slows down, and stacks up on itself. That is why a boat offshore may feel nothing while the harbor behind it is destroyed.
The most important thing to understand is that a tsunami is not one wave. It is a series of surges that can keep coming for 12 hours or more, and the first one is very often not the largest. In 1960 the third wave was the killer in Hilo. People who went back down to check on their homes after the water pulled out died in the wave that followed.
Hawaiʻi’s tsunami record, with dates and arrival times
Here is the record we get asked about most, with how long the wave took to reach us. Notice the split between events that gave us most of a day and the two that gave us minutes.
| Date | Source | Arrival in Hawaiʻi | What happened |
|---|---|---|---|
| April 2, 1868 | Kaʻū, Hawaiʻi Island (local) | About 12 to 20 minutes | Around 77 deaths. Run-up near 45 feet (13.7 m) at ʻĀpua Point |
| April 1, 1946 | Aleutian Islands, Alaska | About 4.9 hours, waves just after 7 a.m. | 159 deaths statewide, 96 in Hilo. No warning system existed |
| November 4, 1952 | Kamchatka, Russia | Overnight Pacific crossing | Damage in Hilo Bay and Honolulu, no deaths |
| March 9, 1957 | Aleutian Islands, Alaska | Pacific crossing | About $5 million damage, Hilo run-up near 13 feet (3.9 m), no deaths |
| May 23, 1960 | Valdivia, Chile | About 15 hours, Hilo Bay just after midnight | 61 deaths in Hilo despite a warning being issued |
| March 28, 1964 | Prince William Sound, Alaska | About 5.4 hours to Hilo | Run-up near 10 feet (3 m), limited damage |
| November 29, 1975 | Kalapana, Hawaiʻi Island (local) | About 10 minutes | 2 deaths at Halape. Run-up to 47 feet (14 m) |
| February 27, 2010 | Maule, Chile | Sirens at 6 a.m., waves late morning | Coastlines cleared, no major damage, all clear early afternoon |
| March 11, 2011 | Tōhoku, Japan | Warning 9:28 p.m., waves near 3 a.m. | Damage in Kona and Maui harbors, about 2 m at Kahului |
| October 27, 2012 | Haida Gwaii, Canada | Warning near 7 p.m., waves near 10:30 p.m. | Waves to 5 feet (1.5 m), Waikīkī hotels moved guests upstairs |
| July 29, 2025 | Kamchatka, Russia | Warning 2:43 p.m., first waves near 7:10 p.m. | Hilo gauge 4.9 feet (1.5 m), Kahului 4 feet (1.2 m), statewide evacuation |
Three of these deserve more than a table row. April 1, 1946 is the one that changed everything. An 8.6 magnitude earthquake in the Aleutians sent a wave that reached Hilo in under five hours, and because there was no warning system at all, people walked down to the exposed reef to look at stranded fish. It killed 159 people in Hawaiʻi, 96 of them in Hilo, and it is the reason the United States built its tsunami warning capability starting in 1948 and 1949. What is now the Pacific Tsunami Warning Center grew directly out of that morning.
May 23, 1960 is the harder lesson, because that time we did have a warning. The largest earthquake ever recorded, a 9.5 off Chile, sent a wave that took about 15 hours to cross the Pacific and entered Hilo Bay just after midnight. The warning went out. Some people evacuated, some did not, and some came back too early. Sixty one people died. A warning only works if people act on it.
November 29, 1975 is the one that keeps us honest about local events. A 7.7 magnitude earthquake struck Kalapana at 4:48 a.m., the shaking lasted more than 30 seconds, and the tsunami began arriving about ten minutes later. A Boy Scout troop camping at Halape was caught between falling rock and rising water. Two people died and 19 were injured. The official warning went out after the first wave had already come ashore. No system on earth could have beaten that clock.
The two clocks: far away versus right here
Almost everything about how you should react comes down to where the earthquake happened, because that determines how much time you have.
Most tsunamis that reach Hawaiʻi come from distant sources around the Pacific rim, and honestly that is the good news in a bad situation. The overwhelming majority of large earthquakes out there never generate a destructive tsunami for us at all, and when one does, the crossing takes hours. Deep ocean sensors and tide gauges detect the wave in open water, the Pacific Tsunami Warning Center models where it is headed and how big it will be, and the sirens sound with time to spare. In July 2025 the warning was upgraded at 2:43 in the afternoon and the first waves did not reach Kauaʻi until about 7:10 that evening. That is more than four hours to move people. Use that kind of window and follow instructions, and you will be fine.
Local events are the other clock, and they are the reason we want you to read this whole section. If you feel a strong earthquake while you are in Hawaiʻi, it very likely originated on Hawaiʻi Island, and it is very likely tied to volcanic activity and the slow, enormous movement of the volcanoes’ flanks. Those are the quakes that produced 1868 and 1975. A locally generated tsunami can be on the beach in ten minutes or less. There is no time for a warning center to model anything, no time for sirens to be the thing that saves you, and no time to look at your phone.
So the rule is simple and worth memorizing. If the shaking is strong enough to knock you off your feet, or if it goes on for 20 seconds or longer, that shaking is your warning. Do not wait for a siren. Do not wait for confirmation. Move inland and uphill immediately, and stay there until officials say it is over.
How you will be told
Hawaiʻi runs what emergency managers call the largest single integrated outdoor warning siren system in the world, roughly 400 sirens statewide. The monthly test on the first working day at 11:45 a.m. is a steady tone for about 50 seconds. Learn that sound while you are on vacation, because if you hear it at any other time, it is not a test and you should immediately turn on a radio, a TV, or your phone for instructions.
During a real distant-source event, the sirens sound repeatedly as the wave gets closer. In the July 2025 warning they went off three hours out, two hours out, one hour out, and again 30 minutes before the first wave. You will also get a Wireless Emergency Alert on your phone, the kind that overrides silent mode, plus broadcasts on local radio and TV and on NOAA Weather Radio. When there is time, county emergency crews and first responders also work the coastal neighborhoods directly, rolling through with loudspeakers and knocking on doors to make sure people in low lying areas actually heard the message. If someone in a uniform tells you to go, go.
It also helps to know the four alert levels, because they are not interchangeable. An information statement means an earthquake happened and there is no threat to us. A watch means a tsunami may reach us later and you should get ready to act. An advisory means dangerous currents and surges are expected in and near the water, so get out of the ocean and off the beach, though broad flooding is not expected. A warning means damaging flooding is expected or already happening, and evacuation is the instruction. Each county, not the warning center, runs its own evacuations and issues its own all clear.
The warnings nature gives you
Sirens do not always come in time, and for a local event they almost certainly will not. Nature gives its own warnings, and there are three that are recognized and reliable.
The first is the shaking we described above. The second is the ocean behaving in a way you have never seen, and this is the one that has killed the most curious people in history. If the water pulls back and drains away from the shoreline, exposing reef, sand flats, and fish flopping where there should be waist deep water, a tsunami is coming and the water is going to come back much faster and much higher than it left. That is not a photo opportunity. That is your last free warning. Turn around and run. The third sign is sound: a loud roar offshore, often described as a freight train or a jet engine, when there is no storm to explain it.
People also talk about animals knowing first, and there is something to it, though we want to be straight with you about how much. After the 2004 Indian Ocean tsunami there were many accounts of birds lifting off the coast in mass, dogs refusing to go near the water, and livestock breaking for higher ground before anything was visible. Researchers think animals may pick up seismic vibration or infrasound that we cannot feel. But those reports are largely anecdotal and they have never been developed into anything you can depend on, so please treat it the right way: if the seabirds go up all at once and the shoreline goes strangely quiet, let it sharpen your attention and get you looking at the water. Never treat calm animals as an all clear, and never wait on an animal when the ground has already shaken or the ocean has already pulled back.
What to do, and what not to do
If you are at the beach and you feel long or violent shaking, or you see the water recede, or you hear that roar, move immediately. Go inland, go uphill, and keep going. Do not stop to gather your things, do not go back to the car for a cooler, and do not stand on the beach filming. Getting a few blocks inland and above the flood zone is worth more than any head start you think you are getting by driving.
If you are in a neighborhood during an official warning with hours of lead time, follow the county’s instructions and leave the evacuation zone early. Roads clog fast, and if you can walk out of the zone, walking is often better than driving. During the 2012 warning the only death in Hawaiʻi was a traffic crash during the evacuation itself, not the wave. Move early, move calm, and give yourself margin.
Never go down to the shoreline to watch a tsunami arrive. It sounds obvious written down, and it is still the single most common way people die in these events. Do not go surfing on it, do not go to the harbor to move your boat once a warning is active, and do not go sightseeing at the lookout. Along with that, stay out of rivers and stream mouths, because surges push far up them.
Know your zone before you need it
The most useful ten minutes you will ever spend is finding out, right now, whether where you are sleeping tonight sits in an evacuation zone. Hawaiʻi publishes tsunami evacuation zone maps by address, and you can check yours through the Hawaiʻi Emergency Management Agency or the interactive NOAA evacuation zone map. The zones are printed in the front of local phone books and posted on signs along coastal roads too. Official messages come from the Pacific Tsunami Warning Center.
Visitors staying in Waikīkī or any beachfront hotel should ask one question at check in: what is the tsunami plan for this building? Most high rises use vertical evacuation, which means guests move up rather than out. The guidance is a steel or reinforced concrete building of about ten stories or more, and you want to be on the fourth floor or higher. That is exactly what Waikīkī hotels did in both 2012 and 2025, moving guests to upper floors rather than pushing thousands of people into gridlocked streets. If you are in a low rise or a ground floor unit near the water, you need a route inland instead, and you should know it before you unpack. Our guide to where to stay on Oʻahu breaks down which areas sit right on the water.
What to have ready
Hawaiʻi’s preparedness guidance is stricter than most of the mainland for one simple reason: we are 2,400 miles (about 3,900 km) from the nearest continent, and if our harbors and airport go down, resupply is not quick. HI-EMA asks residents to keep 14 days of supplies, not the three days you may have heard elsewhere. That means about one gallon (3.8 liters) of water per person per day, two weeks of food that does not spoil, a can opener, a battery powered radio, flashlights, a two week supply of any prescription, a first aid kit, cash for when card systems are down, copies of important documents in something waterproof, and closed shoes rather than slippers, because you may be walking over debris.
If you are visiting, you do not need a two week pantry in your hotel room. What you do need is a charged phone with emergency alerts turned on, shoes you can move in, your ID and medications somewhere you can grab in ten seconds, and a plan you have actually said out loud with the people you are traveling with. We keep the same short list for storm season, and our hurricane season guide covers the overlap in more detail.
After the first wave
This is where people get hurt after the danger seems to have passed. Surges keep arriving for hours, sometimes for more than half a day, and later waves are frequently larger than the first. The water in between is full of debris, and the currents inside harbors and channels stay violent long after the surface looks calm. Do not go back into the evacuation zone because the water looks normal, and do not judge safety by the sirens going quiet.
Wait for your county to issue the official all clear, then go back. Stay out of the ocean until officials say the advisory is lifted, even if the surf looks fine, and check the current conditions before you get back in the water.
Learn the history in person
If you want this to stop being abstract, spend an hour at the Pacific Tsunami Museum in Hilo, a town that was rebuilt around this exact hazard. It sits in an old bank building right where the 1946 and 1960 waves came through.
📍 Pacific Tsunami Museum, 130 Kamehameha Ave, Hilo, Hawaiʻi Island. Admission runs about $8 for adults, $7 for seniors, and $4 for keiki, with kids under 6 free and free entry for Hawaiʻi residents on First Saturdays. Hours have generally been 10 a.m. to 4 p.m., but the museum has been operating on a limited basis during a revitalization project, so call ahead at (808) 935-0926 before you drive over. The survivor accounts are the part that stays with you. Pair it with a day at Hawaiʻi Volcanoes National Park, since the same forces that build this island are the ones that shook it in 1868 and 1975.
None of this should keep anyone away from Hawaiʻi. Damaging tsunamis are rare here, the warning system is genuinely excellent, and the vast majority of visitors will never experience anything beyond a monthly siren test and a story to tell. But the ocean here is not scenery, it is a neighbor, and the families who have lived through these mornings would all tell you the same thing: know the signs, know your zone, and move early. If the water pulls back, do not go look. Run, and take everybody with you.
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