PVMBG reported that during 1-3 October dense gray plumes rose 50-300 m above Raung’s summit; neither eruptions nor gas emissions were visible afterwards, through 26 November. Seismicity decreased and deflation was recorded. The Alert Level was lowered to 1 (on a scale of 1-4) on 27 November, and the public was warned to stay away from the summer 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.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)