On 22 April at 1802 an ash explosion occurred at Karangetang that was accompanied by the ejection of incandescent volcanic material. The resultant ash column rose to ~1,750 m above the volcano, and incandescent material was ejected to ~750 m above the volcano. Ash was deposited on the volcano's W slope, including in the villages of Lehi, Mini, Kinali, and Hiung. The explosion was followed by lava avalanches to the W and S and pyroclastic flows toward Batang River to a runout distance of 2,250 m. Another explosion occurred on 24 April that produced an ash cloud to ~750 m above the volcano. Generally, during 21 April to 4 May, low-level ash plumes rose above South Crater, and glowing was seen up to 25 m above the crater. Karangetang 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)