Based on observations conducted at the Karangetang Volcano Observation Post in the village of Salili, PVMBG reported during 30 September-7 October that lava flows traveled as far as 200 m S. Incandescent avalanches from the fronts of lava flows traveled as far as 2 km E down the Batuawang and Kahetang drainages, and 1 km down the Batang (S) drainage. Seismicity decreased, but continued to be dominated by signals characteristic of avalanches. Harmonic tremor was also detected. The Alert Level remained at 3 (on a scale of 1-4); visitors and residents were warned not to approach Karangetang within a 4-km radius. Based on analyses of satellite imagery and wind data, the Darwin VAAC reported that on 8 October an ash plume rose to an altitude of 2.7 km (7,000 ft) a.s.l. and drifted 65 km E.

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)