Based on observations conducted at the Karangetang Volcano Observation Post in the village of Salili, PVMBG reported that white plumes rose as high as 250 m above the Main Crater and 25 m above Crater II during 22-29 July; foggy conditions occasionally prevented views. Incandescence from the lava dome was observed at night. Incandescent avalanches from the fronts of 150-m-long lava flows traveled as far as 2.5 km E down the Batuawang and Kahetang drainages. Seismicity was dominated by tremor and signals characteristic of avalanches, with rare volcanic earthquakes. The Alert Level remained at 3 (on a scale of 1-4); visitors and residents were warned not to approach Karangetang within a 4-km radius.

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)