What should you do when a tsunami warning is issued?

Short answer. When a tsunami warning is issued, leave the hazard zone at once for high ground or as far inland as possible ¹, on foot where you can ⁵. Ready.gov suggests 100 feet (about 30 m) above sea level or one mile inland ². If the ground shakes hard or the sea drains away, go without waiting for a warning ¹². Stay away until officials say it is safe ¹.

What are the natural warning signs of a tsunami?

A tsunami caused by a nearby earthquake can arrive before any official alert. The Japan Meteorological Agency (JMA) states plainly that "tsunamis may hit before warnings are issued if the source region is near the coast" ⁴. That is why the U.S., Chilean and Indonesian guidance cited here treats certain signs as a warning in their own right.

The U.S. National Weather Service lists three natural warnings ¹:

• a strong or long earthquake;
• the ocean acting strangely, for example draining away suddenly;
• a loud roar coming from the ocean.

Ready.gov adds "a sudden rise or wall of water" and "sudden draining of water showing the ocean floor" ². Chile's SENAPRED tells people in an evacuation area to leave at once if they feel an earthquake that makes it hard to stay on their feet, or if the sea pulls back unusually after a quake ⁵. In Indonesia, a BMKG station head describes a "20-20-20" self-evacuation rule: shaking that lasts more than 20 seconds is a primary danger signal, people may have roughly 20 minutes before a local tsunami arrives, and they should head for ground at least 20 metres above sea level ⁸.

The NWS sums up the difference: an official warning means a tsunami is likely, while a natural warning means one is possible and "could arrive within minutes" ¹. Ready.gov says to leave as soon as you see any natural sign or receive an official warning ².

What do the official warning levels mean?

Each country runs its own system, and the names do not line up exactly. The table below summarises four of them.

JMA issues its warnings about three minutes after a quake, sometimes as early as two minutes ⁴. In BMKG's 8 June 2026 bulletin, the earthquake struck at 06:37:42 local time and the tsunami warning went out at 06:40:42 ⁷. Close to the source, a tsunami may arrive before any warning is issued ⁴, which is why natural signs come first.

Where should you go: up or inland?

The goal is to get above or beyond the reach of the water.

• High ground or inland. The NWS says to go to your safe place outside the hazard or evacuation zone, or, if you cannot reach it, "as high or as far inland (away from the water) as possible" ¹. Ready.gov gives 100 feet above sea level or one mile inland as a benchmark ².
• Chile's 30-metre line. Chile defines the area to evacuate as everything below 30 m above sea level, and its planning guide aims for residents to reach safety within 15 minutes or less ⁶.
• On foot, not by car. SENAPRED tells people in coastal towns to evacuate on foot and leave vehicles where they do not block evacuation routes. On rural roads, slow down and head away from the coast ⁵.
• Avoid rivers. SENAPRED warns not to cross estuaries or rivers, because a tsunami can travel several kilometres inland along them ⁵. JMA's warnings also cover "coastal or river areas" ⁴.
• Vertical evacuation as a last resort. If you cannot get away from the coast, SENAPRED's second option is a building of at least eight floors, climbing as high as possible ⁵. JMA names tsunami evacuation buildings as safe places ⁴. Whether a given structure can resist a tsunami is a question for a qualified engineer, not a judgement to make on the spot.

Evacuation routes in the U.S. are often marked by a sign showing a wave with an arrow pointing toward higher ground ².

What if you are on a boat or in the water?

Ready.gov says that if you are in a boat, face the waves and head out to sea. In a harbour, go inland. If you are in the water, grab onto something that floats, such as a raft or tree trunk ². SENAPRED tells boaters to follow the maritime authority's instructions and, if none are available, to head for deep water ⁵.

How long should you stay away from the coast?

Longer than most people expect. Tsunamis are a series of waves, and "the first wave may not be the last or the largest" ¹. The time between wave crests can range from about five minutes to two hours ³.

NOAA says dangerous tsunami currents can last for days ³, and the threat after a warning "may continue for several hours after initial arrival" ³. The NWS says to stay out of the hazard or evacuation zone until local officials tell you it is safe ¹. SENAPRED gives the same rule: go home only when the authorities say so ⁵.

What official agencies recommend

• United States (NWS, Ready.gov): leave on any natural sign or official warning, for ground 100 feet up or one mile inland ¹². Stay out until officials give the all-clear ¹.
• Japan (JMA): under a Major Tsunami Warning or Tsunami Warning, evacuate coastal and river areas immediately to high ground or a tsunami evacuation building. Under an Advisory, get out of the water and leave the coast ⁴.
• Chile (SENAPRED, MINVU): evacuate on a strong quake or an unusual sea retreat, on foot, toward the mapped safety areas ⁵. The national planning guide places them above 30 m ⁶. Use an eight-storey or taller building only if you cannot get away ⁵.
• Indonesia (BMKG): follow the Awas / Siaga / Waspada level for your area ⁷. Locally, the "20-20-20" rule calls for evacuating after more than 20 seconds of shaking, to at least 20 m above sea level ⁸.

The agencies disagree on numbers. Height targets range from 20 m in the Indonesian rule ⁸ to 30 m in Chile ⁶ and about 30 m (100 feet) in the U.S. benchmark ². Where your area has a mapped hazard or evacuation zone, that zone comes first: the NWS tells people to reach a safe place outside it ¹.

Frequently asked questions

Should I wait for an official warning before leaving?

No, not if you feel a strong or long earthquake or see the sea draining away. Ready.gov says not to wait for tsunami warnings and evacuation orders ². JMA notes that a nearby tsunami may arrive before warnings are issued ⁴.

Is it safe to return after the first wave?

No. The first wave may not be the largest ¹. Waves can be minutes to two hours apart ³, and dangerous currents can last for days ³. Return only when local officials say it is safe ¹⁵.

What is the difference between a tsunami warning and a tsunami advisory?

In the U.S. system, a warning means widespread inundation is imminent, expected or occurring. An advisory means strong currents or waves dangerous to people in or very near the water ³. In Japan, an advisory corresponds to an expected height of up to 1 m and a warning to up to 3 m ⁴.

Can I drive to high ground?

Chile's SENAPRED tells people in coastal towns to evacuate on foot and leave their vehicle where it does not block evacuation routes ⁵. Chile's planning guide calculates evacuation times at walking pace ⁶.

How far inland is far enough?

Far enough means outside your area's hazard or evacuation zone ¹. As a general benchmark, Ready.gov suggests at least one mile inland or 100 feet above sea level ². Chile uses a 30 m line ⁶.

Next step: your evacuation plan

A tsunami leaves little time to decide, so the route, the meeting point and the walking time need to be worked out in advance. The Phaenyx personal plan ($29 free for a limited time) helps you write down your household's evacuation route, safe place and contacts, using the official sources for your country. Build your Phaenyx plan.

Sources

1. U.S. National Weather Service (NOAA) — Tsunami Safety: During a Tsunami — https://www.weather.gov/safety/tsunami-during (accessed 2026-10-20)
2. Ready.gov (U.S. Department of Homeland Security / FEMA) — Tsunamis — https://www.ready.gov/tsunamis (accessed 2026-10-20)
3. U.S. Tsunami Warning System (NOAA) — Tsunami Frequently Asked Questions — https://www.tsunami.gov/?page=tsunamiFAQ (accessed 2026-10-20)
4. Japan Meteorological Agency — Tsunami Warning/Advisory and Tsunami Information — https://www.data.jma.go.jp/eqev/data/en/guide/tsunamiinfo.html (accessed 2026-10-20)
5. SENAPRED (Chile) — Tsunami — https://senapred.cl/tsunami/ (accessed 2026-10-20)
6. Ministerio de Vivienda y Urbanismo (Chile) — Guía de referencia para sistemas de evacuación comunales por tsunami (octubre 2017) — https://csustentable.minvu.gob.cl/wp-content/uploads/2018/03/GU%C3%8DA-DE-REFERENCIA-PARA-SISTEMAS-DE-EVACUACI%C3%93N-COMUNALES-POR-TSUNAMI.pdf (accessed 2026-10-20)
7. BMKG (Indonesia) — Gempa Bumi M7,7, 236 km BaratLaut Tahuna, tsunami warning bulletin of 8 June 2026 — https://www.bmkg.go.id/gempabumi/berpotensi-tsunami/20260608064042 (accessed 2026-10-20)
8. BMKG (Indonesia) — BMKG Soroti Kerentanan Pesisir Baubau, Dorong Mitigasi Gempa Bumi hingga Banjir Rob — https://www.bmkg.go.id/berita/daerah/bmkg-soroti-kerentanan-pesisir-baubau-dorong-mitigasi-gempa-bumi-hingga-banjir-rob (accessed 2026-10-20)