Indonesia tsunami – A video animation how it happened

During quiet times in between earthquakes (interseismic periods), the oceanic crust is slowly pulled under the continental crust (at about 2 inches/year, the speed fingernails grow). There are places where the plates stick together (locked) and places where they don’t (creeping).

At locked zones, the lower plate pulls the upper plate down with it, causing the island to sink (though at 2 inches/year it is nearly imperceptible). Stress at the locked zone builds.

When the stress becomes too great, the upper plate breaks free and springs back, causing the island to suddenly pop up, an earthquake, and a tsunami.

This “seismic cycle” recurs about every 250 years. comment
This animated video is a good example of what happened during the October 25 Mentawai earthquake. The island on the image could be seen as North Pagai and South Pagai.
The difference in this case was that the wave had a max. height of 3 meters (10 inch) and that the wave only reached the Pagai islands and not the mainland of Sumatra.
The time lapse was in this case also totally different.  As the epicenter was quiet close to the Pagai islands (about 30 km (20 miles) the wave must have reached the island shores in about 10 minutes.

Video and some text courtesy Calltech – California Istitute of Technology on YouTube

Overview page with all the articles we wrote on this dramatic earthquake / tsunami

Latest news page 3

Latest news page 2

Latest news page 1


One Response

  1. […] article, including an animated video, explaining how the earthquake caused the tsunami, available here, and an excellent article on the latest news covering the event, available […]

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