Home > Emergency flood and erosion control resources > Emergency response > FEMA Tsunami

FEMA Tsunami

Tsunamis (pronounced soo-ná-mees), also known as seismic sea waves (mistakenly called "tidal waves"), are a series of enormous waves created by an underwater disturbance such as an earthquake, landslide, volcanic eruption, or meteorite. A tsunami can move hundreds of miles per hour in the open ocean and smash into land with waves as high as 100 feet or more.

From the area where the tsunami originates, waves travel outward in all directions. Once the wave approaches the shore, it builds in height. The topography of the coastline and the ocean floor will influence the size of the wave. There may be more than one wave and the succeeding one may be larger than the one before. That is why a small tsunami at one beach can be a giant wave a few miles away.

All tsunamis are potentially dangerous, even though they may not damage every coastline they strike. A tsunami can strike anywhere along most of the U.S. coastline. The most destructive tsunamis have occurred along the coasts of California, Oregon, Washington, Alaska, and Hawaii.

Earthquake-induced movement of the ocean floor most often generates tsunamis. If a major earthquake or landslide occurs close to shore, the first wave in a series could reach the beach in a few minutes, even before a warning is issued. Areas are at greater risk if they are less than 25 feet above sea level and within a mile of the shoreline. Drowning is the most common cause of death associated with a tsunami. Tsunami waves and the receding water are very destructive to structures in the run-up zone. Other hazards include flooding, contamination of drinking water, and fires from gas lines or ruptured tanks.

How can I protect myself from a tsunami?

Know your tsunami terms

Advisory - An earthquake has occurred in the Pacific basin, which might generate a tsunami.
Warning - A tsunami was, or may have been generated, which could cause damage; therefore, people in the warned area are strongly advised to evacuate.
Watch - A tsunami was or may have been generated, but is at least two hours travel time to the area in Watch status.

What to do before and during a tsunami

The following are guidelines for what you should do if a tsunami is likely in your area:

Turn on your radio to learn if there is a tsunami warning if an earthquake occurs and you are in a coastal area.
Move inland to higher ground immediately and stay there.
Stay away from the beach. Never go down to the beach to watch a tsunami come in. If you can see the wave you are too close to escape it.
CAUTION - If there is noticeable recession in water away from the shoreline this is nature's tsunami warning and it should be heeded. You should move away immediately.

What to do after a tsunami

The following are guidelines for the period following a tsunami:

Stay away from flooded and damaged areas until officials say it is safe to return.
Stay away from debris in the water; it may pose a safety hazard to boats and people.
Save yourself - not your possessions

Learn about floods that can result from tsunamis

Floods are one of the most common hazards in the United States. Flood effects can be local, impacting a neighborhood or community, or very large, affecting entire river basins and multiple states.

However, all floods are not alike. Some floods develop slowly, sometimes over a period of days. But flash floods can develop quickly, sometimes in just a few minutes and without any visible signs of rain. Flash floods often have a dangerous wall of roaring water that carries rocks, mud, and other debris and can sweep away most things in its path. Overland flooding occurs outside a defined river or stream, such as when a levee is breached, but still can be destructive. Flooding can also occur when a dam breaks, producing effects similar to flash floods.

Be aware of flood hazards no matter where you live, but especially if you live in a low-lying area, near water or downstream from a dam. Even very small streams, gullies, creeks, culverts, dry streambeds, or low-lying ground that appear harmless in dry weather can flood. Every state is at risk from this hazard.

For more information about Infrastructure Defense Technologies' flood barriers and erosion control barriers and applications, please call us at 1-800-379-1822, email us at info@metalithH2O.com, info@infrastructure-defense.com or fill out our contact form.

The Metalith H2O
A Division of Infrastructure Defense Technologies
3575 Morreim Drive • Belvidere, Illinois 61008
Phone: 1-800-621-5617 • Fax: 1-815-323-1317
Email: info@MetalithH2O.com

Please fill out our
contact form or speak directly to a Metalith H2O representative at:
1-800-379-1822.

For more information about the Metalith H2O flood fighting barriers, please request our FREE BROCHURE by mail.

Or you can DOWNLOAD it here.