World’s Largest Tsunami Debris Discovered

Tongatapu boulder. (Credit: Courtesy of M. Hornbach)

From Science Daily:

ScienceDaily (Sep. 25, 2008) — A line of massive boulders on the western shore of Tonga may be evidence of the most powerful volcano-triggered tsunami found to date. Up to 9 meters (30 feet) high and weighing up to 1.6 million kilograms (3.5 million pounds), the seven coral boulders are located 100 to 400 meters (300 to 1,300 feet) from the coast.

The house-sized boulders were likely flung ashore by a wave rivaling the 1883 Krakatau tsunami, which is estimated to have towered 35 meters (115 feet) high.

“These could be the largest boulders displaced by a tsunami, worldwide,” says Matthew Hornbach of the University of Texas Institute for Geophysics. “Krakatau’s tsunami was probably not a one-off event.” Hornbach and his colleagues will discuss these findings at the Joint Annual Meeting of the Geological Society of America (GSA), Soil Science Society of America (SSSA), American Society of Agronomy (ASA), Crop Science Society of America (CSSA), and the Gulf Coast Association of Geological Societies (GCAGS), in Houston, Texas, USA.*

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