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Fault Responsible for Indonesian Tsunamis Exposed

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Geologists have for the first time observed the Banda Detachment fault in eastern Indonesia and worked out how it formed.

Lead researcher Dr Jonathan Pownall of The Australian National University said the discovery of what is the world’s largest exposed fault will help researchers assess the danger of future tsunamis in the area, which is part of the Ring of Fire – an area around the Pacific Ocean basin known for its earthquakes and volcanic eruptions.

“The abyss has been known for 90 years but until now no one has been able to explain how it got so deep,” Pownall said. “Our research found that a 7 km-deep abyss beneath the Banda Sea off eastern Indonesia was formed by extension along what might be Earth’s largest-identified exposed fault plane.”

By analysing high-resolution maps of the Banda Sea floor, geologists found that the rocks flooring the seas are cut by hundreds of straight parallel scars. These wounds show that a piece of crust bigger than Tasmania must have been ripped apart by 120 km of extension along a low-angle crack, or detachment fault, to form the present-day ocean floor depression.

Pownall said this fault, the Banda Detachment, represents a rip in the ocean floor exposed over 60,000 km2. “The discovery will help explain how one of the Earth’s deepest sea areas became so deep,” he said.

Pownall said he was on a boat...

The full text of this article can be purchased from Informit.