One of the largest depressions in the earth's crust is slowly consuming undersea volcanoes and to the surprise of geologists seem to reduce the risk of earthquakes.
Tonga Trench is a zone of fractures between Tonga and Samoa. It moved west Pacific plate creeps under the Indo-Australian Plate.
Geologists tend to think that the destruction of the giant volcanoes along a subduction zone should lead to increased earthquakes, but Tony Watts of Oxford University (UK) and his colleagues noticed that in recent times the opposite happens. Where the dying of a huge volcano, Tonga Trench is surprisingly calm with the seismic point of view. But why?
The researchers scanned the bottom sonar and presented their findings at the American Geophysical Union. To address their image shows dozens of giant ancient volcanoes with flat tops.
They add up to an underwater mountain chain Louisville and go west with the Pacific plate at a rate of six centimeters per year. Reaching the edge of the valley, they rush into the abyss.
So, once thought that volcanoes increase the friction between the two platforms, and this leads to increased stress and, consequently, more powerful earthquakes. It appears, however, that by the time the fall in the gutter seamounts already very "shabby." The researchers hypothesize that, breaking, volcanoes are a buffer which facilitates the process of subduction.
The ultimate fate of volcanic remains unclear. Whether their stuff becomes part of the Indo-Australian plate, or drowning in the mantle.
Prepared according to the ABC Science.