During 30 July-12 August seismic activity at Karangetang was dominated by explosion, avalanche, and multiphase earthquakes. A steam-and-ash plume rose to 600 m above the volcano. During 1-12 August lava flows and lava avalanches were rarely observed. On 10 August cold lahars crossed roads as they traveled down the Batu Awang River and the Kahetang River. The volcano was 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)