sentences:  The about-to-be subducted plate is highly faulted, allowing seawater to penetrate into the plate interior, where hydration of mantle peridotite may generate serpentinite.Serpentinite thus generated may carry water deep into the mantle as a result of subduction.The Pacific plate subducts in the IBM trench, so understanding what is subducted beneath IBM requires understanding the history of the western Pacific.