Tsunami

Q: How far inland should I evacuate for a tsunami?

The general guidance is: Move to high ground: 100 feet (30 meters) elevation or higher If no high ground: move at least 2 miles (3 km) inland Go UP, not just away — elevation matters more than distance Context matters: Flat coastal plains: a tsunami can travel miles inland. The 2004 Indian Ocean tsunami reached 2+ miles inland in places. Narrow valleys and river mouths: water funnels and amplifies. Move to ridgelines, not up valleys. Tsunami evacuation zones are marked in many coastal areas — learn yours before an event. If you can't get to high ground: go to the upper floor (3rd floor or higher) of a reinforced concrete building as a last resort. Wood-frame buildings will not survive.

Q: How many waves does a tsunami have?

A tsunami is not a single wave. Key facts: A tsunami is a series of waves (called a wave train) that can arrive over hours The first wave is often NOT the largest — later waves can be significantly bigger Waves can arrive 10 to 60 minutes apart The dangerous surging can continue for 6-12 hours or more This is why you must never return to the coast after the first wave passes. The 2004 Indian Ocean tsunami's most devastating waves were the second and third waves. Stay on high ground until authorities issue an official all-clear — not just until things seem calm.

Q: What should I do if I am on the beach when a tsunami hits?

If you're on the beach and a tsunami is imminent: RUN to high ground immediately — every second counts Head for the nearest high ground, steep hill, or upper floors of a concrete building Go on foot if possible — roads will be congested Never stop to gather belongings — your life is the priority If the ocean suddenly recedes exposing the sea floor, that IS the warning — RUN If caught in the water: Grab onto something that floats — a door, tree, roof debris Try to stay on top of the water — don't fight the current Watch for debris in the water — this causes most tsunami injuries Once the surge stops, get to solid ground before the water recedes (the outflow is equally dangerous)

A tsunami can travel across the ocean at 500+ mph and strike with little warning

8 things to do before · 8 steps during · 8 after · 4 questions answered

Last updated 2026-09-25. Written by Project Trinetra, a program of the 501(c)(3) nonprofit Unravel The Love. It is not an official government publication and does not replace instructions from your local emergency authorities.

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Before — Prepare for a Tsunami

Tsunamis are triggered by underwater earthquakes, volcanic eruptions, or landslides. Coastal residents must plan ahead.

#	Do this
1	Know if you live in a tsunami evacuation zone (check local emergency management)
2	Plan two evacuation routes to high ground (100+ feet elevation or 2 miles inland)
3	Learn what tsunami warning sirens sound like in your area
4	Know the natural warning signs: strong earthquake, sudden ocean recession, unusual roaring
5	Keep a go-bag packed near the door with essentials for 72 hours
6	Practice evacuation route with family — walk it, know how long it takes
7	Sign up for NOAA Tsunami Warning Center alerts on your phone
8	If you own a boat, know the harbor procedures for tsunami warnings

During — During a Tsunami Warning

Act immediately. Tsunamis give minutes of warning — not hours.

#	Step
1	If you feel a STRONG earthquake near the coast (20+ seconds), move to high ground IMMEDIATELY — do not wait for an official warning
2	If the ocean suddenly recedes and exposes the sea floor, RUN inland — a tsunami is coming
3	Move to high ground (100+ feet) or at least 2 miles inland
4	Go on FOOT if possible — roads will be jammed and may be damaged
5	NEVER go to the beach to watch a tsunami — you cannot outrun it
6	If caught in the water, grab onto something that floats and ride the current
7	Expect MULTIPLE waves — the first is often NOT the largest. Waves can arrive for hours.
8	Stay away from rivers and streams — tsunami surge travels upstream

After — After a Tsunami

The danger continues long after the first wave.

#	Step
1	Do NOT return to coastal areas until authorities issue an official all-clear
2	Expect aftershocks if caused by earthquake — they can trigger additional tsunamis
3	Stay away from flood water — it may contain debris, sewage, chemicals, and downed power lines
4	Do not enter damaged buildings — structural integrity may be compromised
5	Check on neighbors and help injured if safe to do so
6	Document damage with photos for insurance claims
7	Boil or purify water — water supply may be contaminated
8	Listen to official broadcasts for continuing hazard updates

Supplies specific to this hazard

Go-bag with 72-hour supplies (water, food, medications)
Waterproof flashlight and extra batteries
Whistle for signaling rescue
Waterproof container for important documents
Sturdy walking shoes (not flip-flops)
Emergency radio (hand-crank or battery)

Questions people ask

How far inland should I evacuate for a tsunami?

The general guidance is:

Move to high ground: 100 feet (30 meters) elevation or higher
If no high ground: move at least 2 miles (3 km) inland
Go UP, not just away — elevation matters more than distance

Context matters:

Flat coastal plains: a tsunami can travel miles inland. The 2004 Indian Ocean tsunami reached 2+ miles inland in places.
Narrow valleys and river mouths: water funnels and amplifies. Move to ridgelines, not up valleys.
Tsunami evacuation zones are marked in many coastal areas — learn yours before an event.

If you can't get to high ground: go to the upper floor (3rd floor or higher) of a reinforced concrete building as a last resort. Wood-frame buildings will not survive.

Full Tsunami guide — before, during and after →

Can a tsunami happen without an earthquake?

Yes. While most tsunamis are caused by underwater earthquakes, they can also be triggered by:

Volcanic eruptions — The 2022 Hunga Tonga eruption generated a tsunami that reached coastlines worldwide
Underwater or coastal landslides — The 1958 Lituya Bay, Alaska megatsunami reached 1,720 feet up the opposite hillside
Asteroid impacts — Extremely rare but would generate massive tsunamis
Glacier calving — Large ice chunks falling into water in fjords

This is why tsunami warning systems use ocean buoys and coastal gauges — not just earthquake detection. Even without feeling an earthquake, always take tsunami warnings seriously.

Full Tsunami guide — before, during and after →

How many waves does a tsunami have?

A tsunami is not a single wave. Key facts:

A tsunami is a series of waves (called a wave train) that can arrive over hours
The first wave is often NOT the largest — later waves can be significantly bigger
Waves can arrive 10 to 60 minutes apart
The dangerous surging can continue for 6-12 hours or more

This is why you must never return to the coast after the first wave passes. The 2004 Indian Ocean tsunami's most devastating waves were the second and third waves. Stay on high ground until authorities issue an official all-clear — not just until things seem calm.

Full Tsunami guide — before, during and after →

What should I do if I am on the beach when a tsunami hits?

If you're on the beach and a tsunami is imminent:

RUN to high ground immediately — every second counts
Head for the nearest high ground, steep hill, or upper floors of a concrete building
Go on foot if possible — roads will be congested
Never stop to gather belongings — your life is the priority
If the ocean suddenly recedes exposing the sea floor, that IS the warning — RUN

If caught in the water:

Grab onto something that floats — a door, tree, roof debris
Try to stay on top of the water — don't fight the current
Watch for debris in the water — this causes most tsunami injuries
Once the surge stops, get to solid ground before the water recedes (the outflow is equally dangerous)

Full Tsunami guide — before, during and after →

Quick facts

If the ocean suddenly recedes exposing the sea floor, a tsunami is coming — RUN to high ground immediately.
A tsunami is not one wave — it's a series. The first wave is often NOT the largest. Stay on high ground for hours.
Tsunamis can travel 500+ mph across open ocean. You will not see it coming — obey all warnings.
Head for 100+ feet elevation or 2 miles inland. Go UP, not just away from the coast.
Never go to the beach to watch a tsunami arrive — people who do this rarely survive.

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