The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) issued a Volcano Observatory Notice for Aviation (VONA) for Raung at 1751 on 12 December, noting that white plumes rose 500 m above the summit and volcanic tremor was recorded by the seismic network. Increasing volcanic activity prompted the release of another VONA at 2003 on 15 December; the Aviation Color Code was raised to Yellow (the second lowest color on a four-color scale). An eruptive event produced a medium-dense to dense ash plume that rose 500 m above the summit and drifted E and SE. According to the Darwin VAAC the ash plume had dissipated by 0940 on 16 December. 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)