The Earth's outer layer is made up of a series of moving, interacting plates whose motion at the surface generates earthquakes, creates volcanoes and builds mountains. Geoscientists have long sought to understand the plates' fundamental properties and the mechanisms that cause them to move and drift, and the questions have become the subjects of lively debate. A study published online Feb. 27 by the journal Science is a significant step toward answering those questions.

Researchers led by Caroline Beghein, assistant professor of earth, planetary and space sciences in UCLA's College of Letters and Science, used a technique called seismic tomography to study the structure of the Pacific Plate -- one of eight to 12 major plates at the surface of the Earth. The technique enabled them to determine the plate's thickness, and to image the interior of the plate and the underlying mantle (the layer between the Earth's crust and outer core), which they were able to relate to the direction of flow of rocks in the mantle.

"Rocks deform and flow slowly inside the Earth's mantle, which makes the plates move at the surface," said Beghein, the paper's lead author. "Our research enables us to image the interior of the plate and helps us figure out how it formed and evolved." The findings might apply to other oceanic plates as well.

Even with the new findings, Beghein said, the fundamental properties of plates "are still somewhat enigmatic."

Source: e! Science News - See full article