On 29 October at 0029 an explosion from Crater IV, in the southern portion of the main crater, produced a gray cloud that rose 1.5 km above the crater. During 22-28 October white plumes rose 600 m above main crater, and 50-100 m above Crater II. A "red reflection" was observed reaching up to 75 m above the crater. The number of deep volcanic earthquakes increased compared to the previous week, but no seismicity associated with eruptive activity was recorded. Multiphase earthquakes, associated with lava dome growth, continued to be detected. The volcano remained at Alert Level 2 (on a scale of 1-4).

Geological Summary. Karangetang (Api Siau) volcano lies at the northern end of the island of Siau, about 125 km NNE of the NE-most point of Sulawesi. The stratovolcano contains five summit craters along a N-S line. It is one of Indonesia's most active volcanoes, with more than 40 eruptions recorded since 1675 and many additional small eruptions that were not documented (Neumann van Padang, 1951). Twentieth-century eruptions have included frequent explosive activity sometimes accompanied by pyroclastic flows and lahars. Lava dome growth has occurred in the summit craters; collapse of lava flow fronts have produced pyroclastic flows.

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