ナスカプレート
The ridge is buoyant, resulting in flat slab subduction of the Nazca Plate underneath Peru. Buoyancy is related to crustal age, and the buoyancy effect can be seen in oceanic crust aged from 30-40 Ma. The Nazca Plate is dated to 45 Ma where it subducts into the Peru-Chile trench. The extreme thickness of the buoyant ridge is responsible for the flat slab subduction of the older underlying plate. Modeling has shown that this type of subduction is only concurrent with submarine ridges, and accounts for approximately 10% of convergent boundaries. The most recent estimate of the subduction angle for the Nazca Plate is 20° to a depth of at inland. At depth, approximately inland, the plate shifts to a horizontal orientation, and continues to travel horizontally for up to inland, before resuming subduction into the asthenosphere.