The 1 x 2.7 km island of Iwo-Tori-shima (also known as Okinawa-Tori-shima), located north of the largest island of the Ryukyus, Okinawa, is composed of two andesitic volcanoes.  Tori-shima (Bird Island) is a common name for offshore islands in Japan.  Kusuku lava dome occupies the center of the inner of two sommas on the SE-most volcano.  The summit crater of the NW-most volcano, Iwo-dake, contains a small lake, solfataras, and sulfur deposits that were mined in the past.  Historical eruptions dating back to 1664 have consisted of mild-to-moderate explosive activity.