PVMBG reported that daily dense white gas-and-steam plumes from Karangetang were visible rising as high as 300 m and drifting multiple directions during 5-11 July. Periodic webcam images published in the reports showed incandescence at Main Crater (S crater) and from material on the flanks of Main Crater. PVMBG issued Volcano Observatory Notices for Aviation (VONAs) about eruptive events at 0759 and 0850 on 10 July; images showed what appeared to be pyroclastic flows descending the S flank of Main Crater. The Alert Level remained at 3 (on a scale of 1-4) and the public were advised to stay 2.5 km away from Main Crater with an extension to 3.5 km on the S and SE flanks.

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)