Izu Peninsula

The Izu Peninsula juts into the Pacific coast of Honshu, Japan, west of Tokyo, covering about 1,421 square kilometers with Mount Amagi, at 1,406 meters, its highest point. The peninsula was built where the Philippine Sea Plate collides with the Okhotsk Plate at the Nankai Trough, a collision that also produces the triple tectonic junction beneath nearby Mount Fuji. Its southern portion is composed largely of breccia, while its central and northern portions consist of numerous highly eroded volcanoes centered on the Amagi mountain range, whose submerged extensions continue underwater into Sagami Bay and Suruga Bay. The Kano River, the peninsula's main waterway, flows through a graben valley opened by the same plate tectonics that built the peninsula. That tectonic setting keeps the region geologically active today, producing frequent earthquake swarms, tsunamis and abundant hot springs. This entity documents the Izu Peninsula specifically as a geological formation, a peninsula of eroded volcanoes built at a colliding-plate boundary.