How the Earth’s Pacific plates collapsed »
Scientists drilling into the ocean floor have for the first time found out what happens when one tectonic plate first gets pushed under another. The international expedition drilled into the Pacific ocean floor and found distinctive rocks formed when the Pacific tectonic plate changed direction and began to plunge under the Philippine Sea Plate about 50 million years ago. "It's a bit like a rugby scrum, with two rows of forwards pushing on each other. Then one side goes down and the other side goes over the top," said study leader Professor Richard Arculus, from the Research School of Earth Sciences. "But we never knew what started the scrum collapsing," said Professor Arculus. The new knowledge will help scientists understand the huge earthquakes and volcanoes that form where the Earth's plates collide and one plate gets pushed under the other. As part of the International Ocean Discovery Program, the team studied the sea floor in 4,700 metres of water in the Amami Sankaku Basin of the north-western Pacific Ocean, near the Izu-Bonin-Mariana Trench, which forms the deepest parts of the Earth's oceans.
