The VSI reported that during 23-29 January explosive activity continued, with explosions on both 25 and 28 January. At 2227 on 25 January a minor explosion produced a thick ash plume that rose 700 m above the volcano, blew to the W, and dropped ash over the sea. The explosion also produced a lava avalanche that traveled ~1,250 m down the Kelitu River. The second explosion during the report period occurred at 2109 on 28 January and produced a Strombolian-type eruption with glowing ejecta that reached up to 300 m above the crater. In addition, a black ash-filled plume rose to ~1 km above the volcano. The explosion opened a new crater in the lava dome and produced a lava avalanche that traveled ~1.5 km down the W slope of the volcano. 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)