Worlds largest tsunami debris discovered on the shores of Tonga
September 26th, 2008 - 4:08 pm ICT by ANIWashington, September 26 (ANI): A line of massive boulders on the western shore of Tonga may be evidence of the worlds largest tsunami debris, which is up to 9 meters (30 feet) high and weighing up to 1.6 million kilograms (3.5 million pounds).
The seven house-sized coral boulders were likely flung ashore by a wave rivaling the 1883 Krakatau tsunami, which is estimated to have towered 35 meters (115 feet) high.
Currently, they are located 100 to 400 meters (300 to 1,300 feet) from the coast.
These could be the largest boulders displaced by a tsunami, worldwide, said Matthew Hornbach of the University of Texas Institute for Geophysics. Krakataus tsunami was probably not a one-off event, he added.
Called erratic boulders, these giant coral rocks did not form at their present location on Tongatapu, Tongas main island.
Because the island is flat, the boulders could not have rolled downhill from elsewhere.
The boulders are made of the same reef material found just offshore, which is quite distinct from the islands volcanic soil. In fact, satellite photos show a clear break in the reef opposite one of the biggest boulders.
Some of the boulders coral animals are oriented upside down or sideways instead of toward the sun, as they are on the reef.
According to Hornbach, the Tongatapu boulders may have reached dry land within the past few thousand years.
Though their corals formed roughly 122,000 years ago, they are capped by a sparse layer of soil, and the thick volcanic soils that cover most of western Tongatapu are quite thin near the boulders.
This suggests the area was scoured clean by waves in the recent past.
Finally, there is no limestone pedestal at the base of the boulders, which should have formed as rain dissolved the coral if the boulders were much older.
Many tsunamis, like the one that struck the Indian Ocean in 2004, are caused by earthquakes. But the boulders location makes an underwater eruption or submarine slide a more likely culprit.
Two more possibilities are that a storm surge could have brought the boulders ashore, or a monster undersea landslide caused the tsunami.
But Hornbachs analyses of adjacent seafloor topography point to a volcanic flank collapse as the most probable source of such a wave.
Future study could indicate how frequently these monster waves occur and which areas are at risk for future tsunamis. (ANI)
- World's biggest Tsunami tossed gigantic boulders 300 metres ashore - Sep 26, 2008
- Mega-tsunami deposited giant coral boulders on Tongas island - Sep 17, 2008
- Increased volcanic activity seen at Indonesia's Mount Anak Krakatau - Nov 02, 2010
- Prehistoric mega tsunami deposited giant boulders in Tonga - Feb 04, 2009
- Strong earthquake hits the South Pacific Ocean, no tsunami warning - Jan 29, 2012
- Powerful earthquake strikes west of Vanuatu, no tsunami alert - Feb 02, 2012
- Powerful quake rocks northern Japan, no casualties - Mar 09, 2011
- Strong 6.4-magnitude earthquake jolts the Pacific Ocean near Tonga - Sep 23, 2011
- Tsunami risk higher than expected in LA, other major cities - Oct 11, 2010
- Strong earthquake strikes off Tonga, no damage reported - Dec 26, 2011
- Scientists make first detailed documentation of tsunami erosion - Oct 29, 2009
- Sea cucumbers could protect endangered corals - Feb 01, 2012
- Gujarat coral reefs a virtual gold mine - Mar 27, 2011
- Tsunamis spawned by Chile quake were tiny, say experts - Mar 01, 2010
- Powerful earthquake, small tsunamis hit Indonesia - Oct 26, 2010
Tags: 5 million, coral animals, coral rocks, corals, earthquakes, hornbach, indian ocean, kilograms, krakatau, massive boulders, pedestal, reef material, satellite photos, tongatapu, tsunami debris, tsunamis, university of texas, volcanic soil, volcanic soils, worlds largest tsunami