BNPB reported that activity at Karangetang had increased. On 7 May at 1400 an eruption that ejected incandescent material and produced a dense ash plume also generated a pyroclastic flow that traveled as far as 4 km E, leveling four houses in Kora-Kora. There were no reported fatalities, and 465 people quickly evacuated. The next day pyroclastic flows descended the S flank 2.5 km, in the Kahetang (E) and Awang drainages. Incandescent material continued to be ejected. 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.

Based on satellite images, the Darwin VAAC reported that on 8 May an ash plume that rose to an altitude of 3 km (10,000 ft) a.s.l. drifted almost 85 km E, and dissipated two days later. On 12 May an ash plume rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted 55 km SW. Pyroclastic flow activity was also reported.

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)