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A tsunami is a series of waves formed in a body of water by the sudden displacement of the entire water column. Most large tsunamis are caused by undersea earthquakes, though landslides, volcanic eruptions, explosions, and even meteorite impacts can also cause them. Tsunamis commonly appear on shore as a rapidly receding tide or rapidly rising flood. Global monitoring systems also provide critical early warning to coastal populations.[1] Tsunamis also sometimes provide natural warning signs to people living on coasts, especially close to the tsunami-causing event.

Why do tsunamis matter?

Tsunami wave. NASA/S. Tomizawa

Tsunamis can be highly destructive, causing extensive loss of life and property damage. They have killed more than 350 people on the coast of the United States since 1946, with losses exceeding half a billion dollars.[2] Even larger tsunamis, like the ones that devastated Chile in 1960, Japan in 2011, and Indonesia in 2004, have hit the U.S. Pacific coastal states in the past and could hit them again.

How can geoscience help inform decisions about tsunami hazards?

This "ghost forest" near the mouth of the Copalis River, Washington, was killed by saltwater tides after an earthquake in 1700 caused the land to subside. USGS/Photo by Brian Atwater

Tsunamis can’t be prevented, but scientists use earthquake information, tide gauges, and tsunami detection buoys to issue early warnings and give people time to evacuate. Others study records of prehistoric tsunamis left in the geologic record along coasts. These studies help determine the probability of tsunamis on different coastlines, leading to better hazard planning and preparedness.

Introductory resources

In-depth discussion of tsunamis, their causes, and tsunami preparedness for a non-expert audience.
Answers to basic questions about tsunamis and tsunami early warning.

Frequent questions


  1. Pacific Tsunami Warning Center, http://ptwc.weather.gov
  2. NOAA/WDC Tsunami Event Database, http://www.ngdc.noaa.gov/nndc/struts/form?t=101650&s=70&d=7

See also

External links

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