2014 Volume 123 Issue 1 Pages Cover01_1-Cover01_2
The 11-kilometer-wide Irosin caldera, which is located at the southeastern tip of Luzon Island, was formed by the eruption of 41 cal kBP Irosin ignimbrite. Bulusan (1565 m), a post-caldera volcano, is an active volcano, which generated phreatic eruptions during historical times. The northern rim of the caldera is covered with post-caldera volcanoes, such as Bulusan and Sharp Peak. Lahar and fluvial deposits filled and built up the southern part of the caldera floor, which has been widely used for rice farming.
(Photograph and explanation: Mitsuru OKUNO and Masayuki TORII)