Webcam images of Karangetang published in PVMBG daily reports periodically showed incandescence at Main Crater (S crater) and from material on the flanks of Main Crater during 31 May-6 June. Daily white gas-and-steam plumes were visible rising as high as 150 m above the summit and drifting in various directions. According to the Darwin VAAC ash plumes rose as high as 2.1 km (7,000 ft) a.s.l. and drifted SE and E during 2-4 June. 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.

Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM), Darwin Volcanic Ash Advisory Centre (VAAC)