Raung in Eastern Java in the Ijen Plateau is one of Java's most active volcanoes, with frequent explosive eruptions every few years.  It is a massive stratovolcano constructed SW of the rim of the Ijen caldera. Its 3332-m-high, unvegetated summit of Gunung Raung is truncated by a dramatic steep-walled, 2-km-wide caldera where all of the frequent historical eruptions took place.  A prehistoric collapse of Gunung Gadung on the west flank produced a large debris avalanche that traveled 79 km from the volcano, reaching nearly to the Indian Ocean. Raung contains several centers constructed along a NE-SW line, with Gunung Suket and Gunung Gadung stratovolcanoes being located to the NE and west, respectively.