PACIFIC PLATE

Geol. one of the major tectonic divisions of the earth's crust, comprising four sea-floor basins; separated from the Nazca, Cocos, and North and South American plates by the East Pacific Rise and San Andreas fault and bounded in the western Pacific Ocean by a series of major ocean deeps, including the Kuril, Japan, Mariana, Kermadec, and Tonga trenches.