Tsunamis

What it is

Ready.gov: a tsunami is a series of enormous waves caused by earthquakes, underwater landslides, volcanic eruptions, or asteroids. It can travel 20–30 mph with waves 10–100 feet high. Coasts that border the Pacific Ocean or the Caribbean have the greatest risk.

NWS: the first wave may not be the last or the largest. Danger can last hours or days.

Natural warnings

NWS and Ready.gov list three natural warnings. If you notice any of them in a hazard zone, do not wait for an official warning.

• A strong or long earthquake.
• The ocean acting strange: a fast-rising flood, a wall of water, or water suddenly draining away to show the ocean floor.
• A loud roar from the ocean.

What to do

• If there's an earthquake, Drop, Cover, and Hold On first.
• When the shaking stops, move to your safe place outside the hazard zone. If you can't reach it, go as high and as far inland as possible.
• Ready.gov says to pick shelters 100 feet or more above sea level, or at least one mile inland.
• If you're outside the hazard zone and get a warning, stay where you are unless officials say otherwise.
• Evacuation routes are often marked by a wave with an arrow pointing to higher ground.
• If you're on the beach and feel any earthquake, no matter how small, move off the beach.
• If you're in a boat, face the waves and head out to sea. If you're in a harbor, go inland.

After

• Stay out of the hazard zone until officials say it's safe.
• Avoid floodwater, which can hide debris and live electricity.
• Stay away from damaged buildings, roads, and bridges.
• Photograph damage for insurance.