Deep earthquakes could reveal secrets of the Earth's mantle

Study uses 350-mile-deep earthquake to make elusive measurements of the Earth's layers

A new study from a University of Chicago scientist suggests there may be a layer of surprisingly fluid rock ringing the Earth, at the very bottom of the upper mantle.

The finding was made by measuring the lingering movement registered by GPS sensors on islands in the wake of a deep earthquake in the Pacific Ocean near Fiji. Published Feb. 22 in Nature, the study demonstrates a new method to measure the fluidity of the Earth's mantle.

"Even though the mantle makes up the largest part of Earth, there's still a lot we don't know about it," said Sunyoung Park, a geophysicist with the University of Chicago and the lead author on the study. "We think there's a lot more we can learn by using these deep earthquakes."