The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported increasing volcanic activity at Raung on 16 May. At 0551 an observer saw an ash plume rise to around 1,250 m above the summit and drift S to SW. According to the Darwin VAAC the plume had dissipated by 1140 that same day. The Alert Level remained at 2 (on a scale of 1-4) and the public was warned to stay 3 km away from the summit crater.

Geological Summary. Raung, one of Java's most active volcanoes, is a massive stratovolcano in easternmost Java that was constructed SW of the rim of Ijen caldera. The unvegetated summit is truncated by a dramatic steep-walled, 2-km-wide caldera that has been the site of frequent historical eruptions. A prehistoric collapse of Gunung Gadung on the W flank produced a large debris avalanche that traveled 79 km, 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 W, respectively.

Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM), Darwin Volcanic Ash Advisory Centre (VAAC)