Île Saint-Paul

The uninhabited triangular island of St. Paul is located near the axis of the East Indian Ocean Ridge, 80 km S of Amsterdam Island. It is composed of an older tuff cone surmounted by a basaltic stratovolcano with a 1.8-km-wide caldera. The entire NE half of the volcano was submerged following collapse along a NW-trending fault. This breached the central caldera, leaving an 80-m-deep bay connected to the ocean by a narrow channel. Geothermal areas are located near the caldera rim and along the margins of the caldera bay. The only recorded eruption took place in 1793 from a vent on the lower SW flank.