PVMBG reported that, although inclement weather conditions often prevented visual observations of Raung during 1 June-19 October, white plumes were occasionally seen rising as high as 300 m above the crater. Seismicity fluctuated but continued to decrease, and then was stable. The Alert Level remained was lowered to 1 (on a scale of 1-4) on 20 October, and the public was reminded not to approach the 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)