About Tsunamis



What are tsunamis, and what causes them?


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.

 

 combined unesco ioc blue eng RHS 20220523   noaa logo rgb 2022

IOC Tsunami
Information Centres

   ITIC logo white circle 300dpi 200x200 20160816     CTIC logo 200x200 300dpi

       ITIC                  CTIC
       ITIC-CAR 

   New Logo IOTIC only 300DPI 200x200     NEAMTIC logo 200x200 300dpi

     IOTIC              NEAMTIC

Facebook 2023 New Icon With Wordmark


yt logo rgb light   vimeo logo blue

Hosted by:
UNESCO/IOC Project Office for IODE Oostende, Belgium
© 2024 International Tsunami Information Center | A UNESCO/IOC-NOAA Partnership
1845 Wasp Boulevard, Building 176, Honolulu, HI 96818, USA | Tel: +1 808 725 6050 | Fax: +1 808 725 6055