Dangers HereTsunami: the natural warning that comes before the official one
In a near-field tsunami the wave can arrive before any official alert reaches your phone. The ground itself is the warning system: strong shaking near a coast, or the sea suddenly drawing back to expose the seabed, means move inland and uphill immediately, without waiting for confirmation.
- 11High risk
- 5Medium
- 0Low
- 16Zones tracked
The three natural warnings
Strong or long earthquake shaking while you are on the coast. The sea receding unusually far, exposing reef and seabed. A loud roar from the ocean, often described as a train or aircraft. Any one of these is enough. In 2004 and in 2011, people who moved on the natural signs survived; people who went to look at the exposed seabed did not.
A tsunami is not one wave
It is a series, and the first is often not the largest. Waves can keep arriving for hours, and the water moving back out to sea is as destructive as the water coming in. Stay at high ground until the authorities say it is over — not until it looks calm.
How to avoid it
- On arrival at a coastal hotel, find the evacuation route and the nearest high ground — this takes two minutes.
- Learn the blue tsunami evacuation signs used across Thailand, Japan, Indonesia and Hawaii.
- If you feel strong shaking at the coast, go inland and uphill at once; do not wait for a siren.
- Never go down to look at a receding sea.
- Go up, not along — vertical evacuation into a tall reinforced building is the fallback where there is no high ground.
- Stay put until an official all-clear; later waves are common.
Where we track it
16 zones in the Dangers Here hazard database, by danger level.
High
- Alaska & Aleutian Islands
- Andaman Sea & Sumatra
- Chile
- Indonesia — Sunda Arc
- Japan — Pacific Coast
- New Zealand
- Peru
- Philippines
- Sri Lanka & South-East India
- Thailand — Andaman Coast
- US & Canada Pacific Northwest (Cascadia)
Medium
- Greece — Hellenic Arc
- Italy — Tyrrhenian & Sicily
- Maldives
- Turkey — Aegean & Eastern Mediterranean
- US West Coast — California
Questions
Where is tsunami a risk?
We track 16 zones for this hazard. 11 are rated high risk, including Alaska & Aleutian Islands, Andaman Sea & Sumatra, Chile, Indonesia — Sunda Arc, Japan — Pacific Coast. 5 are rated medium and 0 low.
How do you avoid tsunami?
On arrival at a coastal hotel, find the evacuation route and the nearest high ground — this takes two minutes. Learn the blue tsunami evacuation signs used across Thailand, Japan, Indonesia and Hawaii. If you feel strong shaking at the coast, go inland and uphill at once; do not wait for a siren.
The three natural warnings
Strong or long earthquake shaking while you are on the coast. The sea receding unusually far, exposing reef and seabed. A loud roar from the ocean, often described as a train or aircraft. Any one of these is enough. In 2004 and in 2011, people who moved on the natural signs survived; people who went to look at the exposed seabed did not.
Get the alerts on your phone
Dangers Here warns you when you enter a hazard zone — even offline, even with the app closed. No account, no tracking, free.
Other hazards
- Africanised bees
- Bears
- Crocodiles
- Getting lost
- Giant hogweed
- Heatwaves
- Hippos
- Jellyfish
- Landmines & UXO
- Landslides
- Manchineel tree
- Methanol poisoning
- Mosquitoes
- Mugging & street robbery
- Oak processionary moth
- Pickpockets
- Quicksand
- Rip currents
- Sea snakes
- Sharks
- Sharp coral
- Shore break
- Sinkholes
- Stonefish
- Ticks
- Underwater caves
- Venomous snakes
- Venomous spiders
- Weever fish
- Wolves