Through further analysis of high-resolution maps of the sea floor, the geologists discovered that the bottom-level rocks were cut by hundreds of straight parallel scars. Indeed, the huge abyss had been formed by “extension along what might be Earth’s largest-identified exposed fault plane,” he said. “I was stunned to see the hypothesized fault plane, this time not on a computer screen, but poking above the waves,” said Pownall in a Science Daily press release. Lead researcher Jonathan Pownall came upon extensions of the fault line on the mountains of the Banda arc islands while on a boat trip. Now, researchers at Australian National University (ANU) and Royal Holloway University of London have confirmed this theory. So the question remained: Why is the Weber Deep as deep as a trench?īased on studies of the sea bed and knowledge of geology, one hypothesis stated that the abyss was the result of an extension along a potential low-angle fault - but this theory had remained unproven. However, the Weber Deep is a forearc basin, which is essentially a depression located in front of the Banda arc (curved chain of volcanic islands), according to New Atlas. The Weber Deep is the deepest point in the ocean that is not in a trench trenches are formed during the subduction of two tectonic plates - when one slides under the other. But until recently, they had been unable to explain how it got so deep. Earth’s biggest exposed faultįor nearly a century, scientists have been aware of a 4.47 mile-deep (7.2 km) oceanic abyss - known as the Weber Deep - located off the coast of eastern Indonesia in the Banda Sea. Below these depths, rocks are probably too warm for faults to generate enough friction to create earthquakes, van der Elst said. The deepest earthquakes occur on reverse faults at about 375 miles (600 km) below the surface. Most earthquakes strike less than 50 miles (80 kilometers) below the Earth’s surface. Individual fault lines are usually narrower than their length or depth. "Plate boundaries are always growing and changing, so these faults develop kinks and bends as they slide past each other, which generates more faults," van der Elst said. Seen from above, these appear as broad zones of deformation, with many faults braided together. The biggest faults mark the boundary between two plates. Īll faults are related to the movement of Earth's tectonic plates. The different styles of faulting can also combine in a single event, with one fault moving in both a vertical and strike-slip motion during an earthquake. Strike-slip faults are usually vertical, while normal and reverse faults are often at an angle to the surface of the Earth. These faults are commonly found in collisions zones, where tectonic plates push up mountain ranges such as the Himalayas and the Rocky Mountains. Reverse faults, also called thrust faults, slide one block of crust on top of another. The Basin and Range Province in North America and the East African Rift Zone are two well-known regions where normal faults are spreading apart Earth's crust. Two blocks of crust pull apart, stretching the crust into a valley.
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