Tsunami Warning Signs and Survival: What You Must Know

Tsunamis can travel at over 500 mph across open ocean and strike coastlines with devastating force. The time between warning and impact can be as little as 10-15 minutes for nearby earthquakes. Knowing the signs and having a plan is critical for anyone living in or visiting coastal areas.

Natural Warning Signs

Official warning systems may fail or be too slow. Know the natural signs:

1. Strong earthquake: Any earthquake you can feel near the coast should trigger immediate inland/uphill movement

2. Ocean recession: The water pulls back dramatically from shore, exposing the sea floor. This is NOT a time for curiosity — run inland immediately

3. Unusual ocean sounds: A loud roaring sound from the ocean, similar to a freight train

4. Rapid rise/fall of coastal water: Unusual tidal behavior outside normal patterns

Evacuation Rules

The single most important rule: Get to high ground or inland as fast as possible.

• Move to elevation 100+ feet above sea level, or at least 2 miles inland
• Go uphill, not just away from the beach — tsunamis travel up rivers and channels
• If you cannot reach high ground, go to the upper floors (3rd+) of a reinforced concrete building
• Do NOT go to the beach to watch
• Do NOT return until authorities give all-clear — multiple waves can come for hours

If Caught in the Water

• Grab something that floats (door, mattress, tree trunk)
• Do not try to swim against the current
• Watch for debris — most tsunami injuries come from impact with debris, not drowning
• If pulled out to sea, float and wait for rescue

Preparation for Coastal Residents

• Know your evacuation routes — practice them
• Have a go-bag ready near the door
• Know the elevation of your home and workplace
• Sign up for local tsunami warning alerts
• Identify the nearest high ground and reinforced concrete buildings
• Practice family reunification plan

After a Tsunami

• Stay away from the coast until officially cleared
• Expect multiple waves over several hours
• Avoid floodwater (contaminated, debris-filled)
• Check for injuries and provide first aid
• Avoid damaged buildings and downed utilities
• Document damage for insurance

HAVEN's Tsunami Scenario

HAVEN includes detailed tsunami preparedness guidance, offline maps with elevation data for evacuation planning, and real-time alerts for Watch subscribers. The app's offline functionality ensures you have access to survival guidance even when all communication infrastructure is destroyed — which is likely in a major tsunami event.