Izu Islands (Japan)
Bayonnaise Rocks symbolize part of the only just exposed rim of a fundamentally submarine 8 to 9 kilometers wide caldera. Most historical eruptions, recorded since the late-19th century, have occurred from Myojin sho, a large post caldera lava dome constructed on the NE rim of the caldera. Deposits from submarine pyroclastic flows associated with growth of the dacitic lava dome mantle the conical dome and extend into the NE part of the caldera and down its outer slopes. An explosive submarine eruption from Myojin sho in 1952 destroyed a Japanese research vessel, killing all 31 on board. Submarine eruptions have also been observed from other points on the caldera rim and outside of the caldera.