Izu Islands (Japan)
A large submarine caldera, Myojin Knoll, lies between Aoga shima and Bayonnaise Rocks volcanoes in the Izu Bonin arc. The 6-7 kilometes wide caldera, one of nine along this arc, has walls 500 to 900 meters high. The high point on the western caldera rim is a pumice mantled remnant of the pre-collapse volcanic complex . The walls of the caldera, also known as Kita-Bayonnaise reveal rhyolitic lava flows, shallow intrusions, and volcaniclastic deposits. A voluminous blanket of coarse rhyolitic pumice from the caldera forming eruption mantles the caldera rim and its outer flanks. Post caldera eruptions formed a lava dome that rises 250 m above the caldera floor. The age of the caldera is not known.