Geologists have discovered the biggest exposed fault on the earth at the Banda Detachment fault in eastern Indonesia and worked out how it formed.
The Banda Detachment, represents a rip in the ocean floor exposed over 60,000 square kilometres.
The discovery will help explain how one of Earth’s deepest sea areas became so deep.
In geology, a fault is a planar fracture or discontinuity in a volume of rock, across which there has been significant displacement as a result of rock mass movement. Large faults within the Earth’s crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, such as subduction zones or transform faults. Energy release associated with rapid movement on active faults is the cause of most earthquakes.
A fault plane is the plane that represents the fracture surface of a fault. A fault trace or fault line is the intersection of a fault plane with the ground surface. A fault trace is also the line commonly plotted on geologic maps to represent a fault.
Since faults do not usually consist of a single, clean fracture, geologists use the term fault zone when referring to the zone of complex deformation associated with the fault plane.
The latest findings will help researchers assess dangers of future tsunamis in the area, which is part of the Ring of Fire — an area around the Pacific Ocean basin known for 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.
By analysing high-resolution maps of the Banda Sea floor, geologists from ANU and Royal Holloway University of London found the rocks flooring the seas are cut by hundreds of straight parallel scars.
These wounds show that a piece of crust bigger than Belgium or 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.