During 10-16 September fewer lava flows and lava avalanches traveled down the flanks of Karangetang than in the previous week. Lava flowed down the Kahetang and Keting rivers as far as 1.5 km, and one-km-long avalanches developed at the ends of these flows. Seismicity was dominated by small explosion and multiphase earthquakes. Emissions of steam and possibly ash at the northern main crater rose to 0.5 km. The volcano remained at Alert Level 3 (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)