Tsunami warning vs advisory vs watch, and when to run

In the United States a tsunami warning means widespread coastal flooding is expected, so move to high ground or inland now. A tsunami advisory means strong currents and waves are dangerous to anyone in or near the water, so get out and stay off the beach. A tsunami watch means a tsunami may reach the area later, usually after a distant earthquake, so stay tuned and be ready to move. In Japan and Indonesia the names and the order differ, and the second level already means evacuate.

That difference is what catches travellers. An American who reads “tsunami warning” on a Japanese screen may think it is the top alert; it is the middle one. Below is each country’s ladder, the natural signs that can beat every alert, and what to do on a beach, in a hotel or on a cruise.

Tsunami warning vs advisory vs watch in the US

Warning means flooding, advisory means dangerous water, watch means maybe later. The National Tsunami Warning Center defines a tsunami warning as a tsunami “with the potential to generate widespread inundation” that is imminent, expected or occurring, with the action “move to high ground or inland”. A tsunami advisory covers a tsunami that can generate strong currents or waves dangerous to people in or very near the water; the action is to stay out of the water and away from beaches and waterways.

A tsunami watch means a tsunami may later affect the watch area, and the action is to stay tuned and be prepared to act. Below those sits the information statement: an earthquake or tsunami has happened that is of interest, but no action is suggested. A watch is often upgraded or cancelled within hours, as the centres measure the actual waves.

How Japan and Indonesia name their tsunami alerts

Both countries put evacuation at their middle level, and both grade alerts by the expected height of the waves. The Japan Meteorological Agency issues a Major Tsunami Warning when the tsunami is expected to exceed 3 metres, a Tsunami Warning for up to 3 metres, and a Tsunami Advisory for up to 1 metre. For both warnings its instruction is to evacuate coastal and river areas immediately to high ground or a tsunami evacuation building. For an advisory it is to get out of the water and leave coastal areas. JMA aims to issue them about three minutes after the earthquake, sometimes two, and since 30 August 2013 a Major Tsunami Warning has been classed as an Emergency Warning.

Indonesia’s agency, BMKG, uses three local-language levels. Awas is for an expected height above 3 metres and calls for full evacuation. Siaga covers 0.5 to 3 metres and calls for evacuation. Waspada is under 0.5 metres and tells local governments to move people away from beaches and riverbanks. If you are in Bali or Lombok and hear “siaga”, leave the beach and go uphill.

The natural warning signs that beat every alert

If the ground shakes hard or long, or the sea behaves strangely, go to high ground without waiting for an official warning. The Weather Service lists three signs: a strong or long earthquake; the ocean acting strangely, such as a fast-rising flood, a wall of water, or the water draining away suddenly; and a loud roar from the ocean. Move as high, or as far inland, as you can.

Two more rules from the same guidance matter for visitors: the danger may last for hours or days, and the first wave may not be the last or the largest. People who go back to the beach to look, or to collect their things, are walking into the second wave.

What to do on a beach, in a hotel or on a cruise

Know your way to high ground before you need it, and follow local officials, not social media.

• On the beach: under a US advisory or a Japanese advisory, leave the water and the shore. Under any warning, or Indonesian siaga or awas, go uphill or inland on foot. Follow the tsunami evacuation route signs where they exist, like the one in our photo from the Oregon coast.
• In a hotel: ask at check-in whether the building is in a tsunami zone and where the evacuation route goes. In Japan, the instruction for both warning levels includes moving to a designated tsunami evacuation building if high ground is too far.
• On a cruise: follow the crew and port authority instructions. If you are ashore when a warning is issued, go to high ground with everyone else rather than back to the pier.
• In Japan: the Japan National Tourism Organization’s Safety tips app pushes earthquake early warnings and tsunami warnings in 15 languages, including English, with an evacuation flowchart.
• Driving: if you can walk to safe ground quickly, walk. Coastal roads jam fast and a car is no protection from moving water.

Our verdict

Learn the ladder for the country you are in, and treat the shaking as the alert. In the US the advisory is the “get out of the water” level and the warning is the “get to high ground” level. In Japan and Indonesia, everything from the middle level up means evacuate. And anywhere on a coast, a strong or long earthquake means move now, before any message arrives.

The same “read the alert, not the beach” logic runs our guide to the US beach hazards statement, and our explainers on hurricane watches and warnings and winter storm alerts.

Elsewhere, the alerts work differently: see what a UK amber weather warning means, how Australian cyclone categories work, and the US extreme cold warning.

Frequently asked questions

Keep reading

Sources: NOAA National Tsunami Warning Center, message definitions (tsunami.gov); National Weather Service, tsunami safety guidance; Japan Meteorological Agency, Tsunami Warning/Advisory and Tsunami Information; BMKG warning-level briefing (Layanan Peringatan dari BMKG, published in the GITEWS tsunami kit); Japan National Tourism Organization, Safety tips app; Yahoo News, Tsunami alerts explained and The difference between a tsunami warning and watch (both 30 July 2025), for the Kamchatka advisories and nearby-quake timing. All read 4 October 2026.

Photos via Pexels: Max J (cover), Jess Loiterton, vitalina.