Insight Into: What Is A Tsunami?

Produced by the Space Telescope Science Institute’s Office of Public Outreach in collaboration with the NASA Earth Observatory.
·       Photo of tsunami waves hitting the coast of Minamisōma in Fukushima prefecture, March 11, 2011: Sadatsugu Tomizawa/AFP/Getty Images

·       Animation of tsunami waves flooding the coast: NOAA

·       Animation showing causes of tsunamis: STScI

Written by Leah Ramsay

Designed by Dani Player and Leah Hustak

Editorial and design input from Margaret W. Carruthers, Timothy Rhue II, John Godfrey, and Claire Blome

Music courtesy of Associated Production Music

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Text, What Is A Tsunami?

 

Tsunamis are one of the most powerful, and misunderstood, natural phenomena on our planet.

 

Neither a true tidal wave nor a single, huge rogue wave, 

 

a tsunami is a series of broad, high-speed waves generated by the sudden displacement of ocean water,

 

often by the movements of rock from an undersea earthquake

 

and more rarely by a landslide or volcanic eruption.

 

Tsunamis can also be caused by a massive meteorite falling into the ocean.

 

Energy is transferred from the moving rock to the ocean, sending waves out in all directions. Tsunamis can travel as fast as 450 miles per hour and maintain speed across entire oceans.

 

In the deep ocean these waves are barely detectable,

 

but they slow down and gain height dramatically as they move into shallower water.

 

These tall, broad waves flood coasts, moving inland like a series of rapidly rising tides or storm surges.