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What Gave Deadly Sumatra Tsunami Its Extra Power

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December 29, 2004 (Image credit: USGS, IKONOS.)

A thick plateau of strong rock along the seabed may have allowed the massive, magnitude 9.1 Sumatra earthquake to reach far closer to the Earth's surface, giving the deadly tsunami it triggered even greater power, according to new research.

The earthquake occurred along a subduction zone, an area where one massive tectonic plate is diving beneath another . As one rocky plate is forced beneath another, sediments are scraped off in the process and accumulate along the subduction zone.

Weaker sediments those with a consistency closer to taffy tend so slow the energy of an earthquake as it races from deep inside the earth toward the seabed. Yet if the sediments are strong more akin to peanut brittle the earthquake can displace larger portions of the seafloor, according to the PlanetEarth Online report.

It appears the plain near Sumatra is made of particularly strong sediments that allowed the quake's rupture to move quickly, thus reaching closer to the seafloor and displacing even more water than it might have otherwise, thus producing a particularly large tsunami.

The research is published online in the June 19 issue of the journal Nature Geoscience.

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