Preparing for a tsunami comes down to two things: knowing what to do before one strikes and reacting fast when it does. The target is to reach ground at least 100 feet above sea level or one mile inland, and in many coastal areas you may have as little as 10 to 15 minutes to get there. That reality makes advance planning non-negotiable.
Know Your Zone Before You Need To
If you live in or visit a coastal area, find out whether your home, workplace, or hotel sits inside a tsunami hazard zone. Many coastal communities publish inundation maps that show exactly which areas would flood. Look for posted evacuation route signs, identify your nearest assembly area, and physically walk or drive the route so it’s second nature. Doing this once while calm saves critical seconds during a real event.
Communities certified under NOAA’s TsunamiReady program have already mapped their hazard zones, installed evacuation signs, and established multiple ways to push warnings to residents. If your town hasn’t done this, you need to build your own plan: pick a destination at least 100 feet in elevation or a mile from the coast, choose two routes in case one is blocked, and make sure every member of your household knows the plan without needing a phone to look it up.
Recognize the Natural Warning Signs
Official alerts from the National Tsunami Warning Center are the most reliable signal, but nature often delivers its own warnings first. A strong earthquake near the coast is the most common trigger. If you feel shaking that lasts more than 20 seconds or is strong enough to make it hard to stand, treat it as a tsunami warning by default. You don’t need to wait for a siren or phone alert.
Other signs include a sudden, unusual retreat of the ocean from the shoreline, exposing the sea floor, or a loud roaring sound from the water. Any of these means you should move immediately. The time between an offshore earthquake and the first wave arriving can be extremely short for locally generated tsunamis, so hesitation is the biggest risk factor you can control.
What To Do When Shaking Starts
Protect yourself from the earthquake first. Drop to your hands and knees, cover your head and neck with your arms, and hold on to sturdy furniture until the shaking stops. Crawl to better cover only if you can do so without moving through debris. Once the shaking ends, shift immediately into tsunami mode: grab your go bag if it’s within arm’s reach, put on sturdy shoes if possible, and head for high ground.
Move on foot if roads are likely damaged or jammed with traffic. Go as high and as far inland as you can. If you cannot reach your planned evacuation point, keep climbing. A hill, a parking garage, an upper floor of a reinforced concrete building: anything is better than staying at sea level. Do not wait for an official evacuation order if you felt the earthquake yourself or saw the ocean behave strangely.
Vertical Evacuation as a Last Resort
In some flat coastal areas, there simply isn’t enough high ground nearby. That’s why a growing number of communities in Washington, Oregon, and other at-risk states have built vertical evacuation structures: purpose-built towers, reinforced buildings, and even artificial hills designed to survive earthquake shaking, aftershocks, soil liquefaction, and hours of repeated tsunami waves. The Shoalwater Bay Indian Tribe’s evacuation tower, for example, has supports extending 55 feet underground, and the Ocosta Elementary School in Washington required 160 concrete piles driven 50 feet deep.
If no purpose-built structure is available, existing buildings made of steel and reinforced concrete may offer refuge on upper floors, but only if they meet height and structural requirements. Wood-frame buildings are not safe. If your community has designated vertical evacuation sites, learn where they are and how to access them quickly.
Build a Go Bag for Coastal Living
A tsunami go bag is different from a standard earthquake kit because you’ll likely be away from your home for at least 24 hours, possibly outdoors, and potentially wet. Keep it light enough to grab and carry at a run. Essentials include water, high-calorie food that doesn’t need cooking, a flashlight, a whistle or SOS signaling device, a portable phone charger (solar if possible), basic first aid supplies, any critical medications, and copies of important documents in a waterproof pouch. Sturdy shoes stored next to the bag save time if you’re evacuating barefoot from bed.
If you’re evacuating to a community assembly area along the coast, plan to stay for a full 24 hours. Wave surges, some larger than the initial wave, can continue arriving throughout that period.
The First Wave Is Not the Last
One of the most dangerous misconceptions about tsunamis is that the threat ends after the first wave hits. It does not. The first wave may not even be the largest or most damaging. Tsunami waves can continue arriving for hours or even days, with later surges sometimes exceeding the initial one. Stay out of the hazard zone until local officials explicitly give the all-clear. People who return to check on property between waves account for a significant number of tsunami deaths.
Health Risks After the Water Recedes
Surviving the waves is only the first challenge. Floodwaters carry a toxic mixture of sewage, fuel, chemicals, and debris. Walking through standing water risks deep cuts from hidden objects, and those wounds can become seriously infected by bacteria that thrive in contaminated soil and water.
After the 2004 Indian Ocean tsunami, doctors expected outbreaks of malaria and cholera, but a different threat emerged instead. Survivors who had been swept through the waves developed a condition called “tsunami lung,” a type of aspiration pneumonia caused by inhaling saltwater contaminated with mud and bacteria. The infections festered when damaged medical infrastructure delayed antibiotic treatment, and in some patients the infection spread from the lungs into the bloodstream and brain, causing abscesses and even paralysis. The bacteria responsible came from the local soil and water, meaning anyone forced underwater during a tsunami is at risk.
If you or someone near you was submerged during a tsunami and later develops a cough, fever, or difficulty breathing, seek medical attention as soon as it’s available. The same goes for any wound that shows signs of infection: redness, swelling, warmth, or discharge. Early treatment with antibiotics is highly effective, but delays make these infections far more dangerous.
Prepare Your Household Now
The most effective tsunami preparation happens long before any warning. A few specific steps make a real difference:
- Practice your route. Walk or drive it with your family so everyone, including children, can do it independently.
- Set a meeting point. Choose a spot on high ground where household members will reunite if separated.
- Sign up for alerts. Register for local emergency notifications and make sure your phone receives Wireless Emergency Alerts.
- Store your go bag by the door. A bag in a closet upstairs adds minutes you may not have.
- Know your building. If you work or stay in a coastal high-rise, learn which floors are above the projected inundation height and whether the building is reinforced concrete or steel frame.
Tsunamis are rare events, but they give very little warning. The people who survive them consistently share one trait: they had a plan and acted on it without hesitation.