Based on analyses of satellite imagery, the Darwin VAAC reported that on 11 March an ash plume from Karangetang rose to an altitude of 2.4 km (8,000 ft) a.s.l. and drifted 55 km SW. According to news reports, lava flows at the summit were visible on 11 March. Blocks originating from the lava dome traveled as far as 2 km down the flanks. Hot gas clouds also descended the flanks. The VAAC also noted that on 13 March an ash plume rose to an altitude of 3.7 km (12,000 ft) a.s.l. and drifted 37 km.

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: Okezone, Darwin Volcanic Ash Advisory Centre (VAAC), Novinite