Tsunamis are series of ocean waves caused by underwater earthquakes, volcanic eruptions, or landslides. Unlike normal waves, tsunamis involve the entire water column, giving them enormous energy. They can travel across oceans at jet speed and strike coasts with devastating force.
Warning time varies from minutes (for locally-generated tsunamis) to hours (for distant tsunamis). Natural warning signs may be the only warning for local events. Understanding these signs and having evacuation plans ready saves lives.
Natural Warning Signs
For local tsunamis, natural signs may be your only warning. Recognize them and act immediately.
Strong earthquake near the coast: If you feel a strong earthquake and are near the ocean, do not wait for official warnings. Move to high ground immediately. The earthquake is your warning.
Ocean recession: If the ocean suddenly pulls back unusually far from shore, exposing sea floor normally underwater, a tsunami may be approaching. Do not go to look. Run inland or to high ground.
Unusual ocean sounds: Roaring sound from the ocean like a freight train may indicate approaching waves.
Official warnings: Tsunami warning sirens, emergency alerts on phones, and broadcast warnings indicate confirmed tsunami threat. Act immediately.
Evacuation Actions
Move immediately when you experience natural warning signs or receive official warnings. Every minute counts.
Go inland or to high ground: Get as far from the coast and as high as possible. Aim for ground at least 100 feet above sea level or 2 miles inland.
Follow evacuation routes: Coastal areas with tsunami risk have marked evacuation routes. Know these before you need them.
If you cannot reach high ground, go to upper floors of reinforced concrete buildings as a last resort. Avoid wood-frame buildings which can be destroyed.
Do not drive if roads are congested. Walking or running may be faster. Tsunami waves can trap vehicles.
Stay away from the coast until authorities declare it safe. Tsunamis arrive in series. The first wave may not be the largest. Danger continues for hours.
Preparation Before Tsunamis
Know your risk: If you live in or visit coastal areas, learn if you are in a tsunami hazard zone. Many coastal communities have hazard maps.
Know evacuation routes: Identify routes to high ground from your home, workplace, and places you frequent. Walk or drive the routes so they are familiar.
Have a go-bag ready: Keep emergency supplies ready for quick evacuation. You may not have time to gather items.
Discuss with family: Everyone should know what to do and where to meet if separated during evacuation.
Practice: Participate in tsunami drills if your community has them. Mental rehearsal also helps prepare.
After a Tsunami
Stay away from flooded areas. Water may be contaminated with sewage, chemicals, and debris. Structures may be unstable.
Watch for hazards: Downed power lines, broken gas lines, and unstable buildings pose continuing dangers.
Do not return to low-lying areas until authorities confirm it is safe. Additional waves may arrive.
Follow official guidance on water safety, building reentry, and cleanup.
Regional Considerations
Pacific Coast (US): Highest tsunami risk in the US. Alaska, Hawaii, and West Coast have warning systems. Cascadia Subduction Zone poses significant local tsunami risk to Pacific Northwest.
Atlantic and Gulf Coast: Lower risk but not zero. Underwater landslides and distant earthquakes could generate tsunamis.
Mediterranean and European coasts: Historical tsunamis have occurred. Some coastal areas have warning systems.
Tsunami Preparedness Checklist
- Know if you are in a tsunami hazard zone
- Know evacuation routes to high ground
- Recognize natural warning signs
- Have go-bag ready for quick evacuation
- Family meeting point established
- Signed up for emergency alerts
- Know warning siren sounds
- Practice evacuation route
Frequently Asked Questions
How much warning will I have?
For distant tsunamis, warning systems may provide hours. For locally-generated tsunamis, you may have only minutes. Natural signs may be your only warning.
How high do I need to go?
Higher is better. Aim for 100 feet above sea level or 2 miles inland. Even getting to higher floors of sturdy buildings helps if you cannot reach high ground.
Can I outrun a tsunami?
In the open ocean, no. On land, you can often reach safety if you act immediately. Do not wait to watch. Move as soon as you have warning.
Is the first wave the biggest?
Not necessarily. Later waves may be larger. Danger continues for hours. Do not return to low areas until officially cleared.
Should I grab my belongings?
No. Saving your life takes priority. If your go-bag is ready to grab, take it. Otherwise, leave immediately without gathering items.
What about boats?
Small boats in harbors face extreme danger. If offshore in deep water, stay there. In harbors, abandon boats and evacuate on foot.
Disclaimer: This guide provides general educational information. Tsunami behavior varies. Always follow official warnings and local emergency guidance.