PVMBG reported that the effusive eruption which began around 1700 on 8 February at Karangetang’s Main Crater (S crater) produced lava flows and lava avalanches that traveled as far as 2 km down the SW and S flanks in drainages leading to the Beha, Batang, Timbelang, Batuawang, and Kahetang rivers. Effusion ended on 1 April and avalanches of material were no longer detected. Seismic signals indicating effusion decreased and by 6 April were no longer being detected. Incandescence at both Main Crater and Crater II (N crater) was visible at night during 1-25 April. White gas plumes were seen rising as high as 200 m above the summit and drifted in multiple directions; weather clouds sometimes prevented views. On 26 April the Alert Level was lowered to 2 (on a scale of 1-4) and the public was warned to stay 2.5 km away from the craters on the S and SW flanks and 1.5 km away on the other flanks.

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)