A fragment of a long-lost tectonic plate is sliding under the North American continent in the southern part of the Cascadia subduction zone, scientists have discovered. This leftover plate fragment could pose a new earthquake risk to the region.
New research, published Thursday (Jan. 15) in the journal Science, revealed that the Pioneer Fragment — a leftover bit of an oceanic plate that disappeared under the North American Plate some 30 million years ago — is now stuck to the floor of the Pacific Ocean and is moving northwest along with that plate.
