Scientists Discover Earth’s Largest Exposed Fault in Indonesia

Geologists from the Australian National University (ANU) and Royal Holloway University of London have discovered the largest-ever exposed fault in eastern Indonesia.

The fault, which is called Banda Detachment in eastern Indonesia, is believed to have caused the formation of a 7-kilometer-deep abyss underneath the Banda Sea.

According to lead researcher Dr. Jonathan Pownall from ANU, the discovery will help researchers assess the risks of future tsunamis in the region, which is located along the Pacific Ring of Fire - an area around the Pacific Ocean basin where about 90 percent of the world's earthquakes and 75 percent of all volcanic eruptions occur, Science Alert reports.

Pownall said he was on a boat going to eastern Indonesia in July when he noticed the prominent landforms consistent with surface extensions of the fault line.

"I was stunned to see the hypothesized fault plane, this time not on a computer screen, but poking above the waves," Pownall said in a statement. "This demonstrates the extreme amount of extension that must have taken place as the oceanic crust was thinned, in some places to zero."

After analyzing high-resolution maps of the Banda Sea floor, the researchers found that the rocks flooring the seas are cut by hundreds of straight parallel scars. According to the scientists, the scars suggest that a piece of giant crust might have been ripped apart by 120 km of extension along a low-angle crack (detachment fault) to form the ocean-floor depression seen today. Pownall said that the Banda Detachment represents a rip in the ocean floor exposed over 60,000 square kilometers.

"The discovery will help explain how one of the Earth's deepest sea areas became so deep," he said.

According to Gordon Lister from ANU Research School of Earth Sciences, this was the first time the fault has been seen and documented.

"We had made a good argument for the existence of this fault we named the Banda Detachment based on the bathymetry data and on knowledge of the regional geology," Lister said in the same statement.

The study was published in the journal Geology.