A Tsunami's Reach

Teletsunamis

map of tsunami travel times for earthquake off the coast of California

Travel time map for a hypothetical earthquake along the northwest U.S. coast

Tsunamis that cross oceans to reach locations more than 1000 kilometers away are called teletsunamis, from the Greek word "tele," meaning distance or distant. These tsunamis travel a few hours or more before reaching distant shores, giving scientists time to estimate wave arrival times and wave heights at locations far from the source.

Modeling

wave energy model for earthquake originating near Lisbon

Wave energy model plus travel times for earthquake originating near Lisbon

Scientists can predict how fast a teletsunami will travel and which coastal areas are particularly at risk by modeling how the tsunami moves across the ocean. The models require information about the seafloor terrain, or bathymetry, as well as the shapes of all land features within or bordering the ocean basin. The size and location of the initial earthquake is also important, particularly for estimating the initial heights of the waves. The initial wave heights are refined as sea level gauge data become available.

Models of Real-life Tsunamis

still graphic showing of modeled tsunami wave propagation across the Pacific Ocean

Simulated tsunami wave from Honshu, Japan propagating across the Pacific Ocean

In the exercise at the end of this lesson, you can watch how tsunamis from large earthquakes at various locations move across the ocean basins. As you view the models of tsunamis generated at different locations, notice:

  • how far the waves travel
  • how fast the waves spread across various regions of the ocean
  • how the waves bend or bounce off coastlines as well as undersea features

Go to the next page to view an animated model of the tsunami originating near the Samoa islands in 2009. Text labels help explain what you are seeing.

Samoa Island Tsunami

Animation of a tsunami model for the 2009 Samoan tsunami

Animation Labels:

  1. 8.1 magnitude earthquake triggers tsunami
  2. Note wave reflections off topographic features that complicate wave pattern
  3. Waves reach Hawaii
  4. Note how waves wrap around New Zealand
  5. Waves reach and reflect off U.S. West Coast

Tsunami Viewer

base map of the Pacific basin, used for the Tsunami's Reach interaction

1. Kuril Islands, Mw 8.3

animation of 2006 tsunami originating near the Kuril Islands

2. Kuril Islands, Mw 8.1

animation of tsunami originating near the Kuril Islands near Japan and propagating across the Pacific

3. Honshu, Japan Mw 9.0

animation of tsunami generated by 2011 Honshu Japan earthquake

4. Solomon Islands, Mw 8.1

animation of tsunami originating near Solomon Islands propagating across the Pacific

5. Vanuatu, Mw 7.6

animation of Vanatu 2009 tsunami propagating across Pacific basin

6. Samoa, Mw 8.0

animation of tsunami originating near Samoa islands September 29, 2009

7. Peru Coast, Mw 8.0

animation of tsunami originating near Peru and propagating across the Pacific

8. Concepcion, Chile, Mw 8.8

animation of tsunami generated from Chile 2010 earthquake as it moves across Pacific basin

Summary

A teletsunami or distant tsunami crosses an ocean to reach locations more than 1000 kilometers away from its source.

Because it can take time to reach distant shores, scientists are able to estimate wave arrival times and wave heights for far-away locations.

These estimates come from computer models that account for seafloor terrain and all land features within or around the ocean basin.

Initial model output is based on information about the size and location of the source earthquake and refined as sea level data become available.

The models provide information about how far and how fast the waves travel and how they are affected by coastlines and undersea features.

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