Underwater mountains under destruction

The startling pictures, created by sonar in waters up to 6 kilometers deep, illustrate how tectonic action is dragging giant volcanoes into a chasm in the seabed, the state-run BBC reported on Tuesday.

The volcanoes, which spread across several thousand kilometers of ocean floor, are moving westward on the Pacific tectonic plate at a speed of up to 6 centimeters per year.

The extraordinary scene was captured along the Tonga Trench during a research expedition last summer, which is a highly active fault line running north from New Zealand towards Tonga and Samoa.

The first images have been released as the findings of a joint project by the universities of Oxford and Durham are presented to the annual conference of the American Geophysical Union.

The project was funded by the Natural Environment Research Council (NERC), a British research council that supports research, training and knowledge transfer activities in environmental sciences.

The Pacific plate is forced downwards into the trench, a subduction zone, where it collides with the Indo-Australian plate. The volcanoes are also carried downwards with the plate.

Oxford researcher Professor Tony Watts said, “Just what happens is still unknown.”

“Are they added to the Australian plate or are they carried down in fragments into the deep earth mantle?”

The trench, reaching a depth of 10.9 kilometers, forms the second deepest stretch of seabed anywhere in the world -- large enough to hold Mount Everest, the world's highest above-water mountain.

The deepest place on Earth is the Mariana Trench in the western Pacific Ocean