During 7-14 October, VSI raised the Alert Level at Karangetang from 2 to 3. During this period, a thick ash plume rose ~400 m above South Crater and incandescent lava avalanches traveled ~250 m toward Nanitu River and ~400 m W toward Beha River. Also, a thin ash plume rose ~50 m above North Crater. On 19 October at 1759 an explosion produced an ash cloud to ~750 m above the volcano. The ash cloud drifted N, depositing ash into the sea. In addition, glowing material was ejected 500 m vertically and landed inside the crater. During 14-21 October, lava avalanches continued to travel down Karangetang's flanks and lava flowed 1,500 m toward Nanitu River, 1,000 m toward Beha River, and 750 m E toward Kahetang River.

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)