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Pacific Coastal and Marine Science Center

Tsunamis and Earthquakes

Life of a Tsunami

Persistence of Tsunami Waves

Do tsunamis stop after they first strike land? No!

Part of the tsunami energy is reflected back to the open ocean and scattered by sharp variations in the coastline. In addition, a tsunami can generate a particular type of coastal trapped wave called an edge wave. Edge waves travel back-and forth, parallel to shore. This results in many arrivals of the tsunami at a particular point on the coast rather than an arrival as a single wave.

Because of the complicated behavior of tsunami waves near the coast, the first amplitude and surge of a tsunami is often not the largest, emphasizing the importance of not returning to a beach many hours after a tsunami initially hits.

Northern California

To illustrate this phenomenon, the simulations below show tsunami wave behavior along the northern California coastline. For visualization purposes, tsunami wave amplitudes are exaggerated and 2.5 hours of elapse time has been compressed into 30 seconds of animation time.

Resonance within harbors and estuaries is not shown in these simulations, but it is another important aspect that contributes to the persistence of tsunami waves.

Note: these animations might take a moment to load, depending on your internet speed. If they do not play immediately upon clicking the play button, please give them some time to load.


View to the south-east.


View to the north-east.

Central California

The simulations below show tsunami wave behavior long the central California coastline. For visualization purposes, tsunami wave amplitudes are exaggerated and 70 minutes of elapse time has been compressed into 20 seconds of animation time.


View to the south-east.


View to the north-east.

 

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URL: https://walrus.wr.usgs.gov/tsunami/persistence.html
Page Contact Information: Laura Zink Torresan
Page Last Modified: 25 May 2016 (lzt)