During 18-24 March, lava avalanches traveled down Karangetang's flanks. On 23 March at 1115 a thunderous sound from the main crater was followed by lava avalanches down the Kahetang and Batu Awang rivers. During the report period, observers noted a thick plume rising 400 m above the crater rim and a 75-m-high "red reflection" rising above the volcano's summit. Seismicity slightly decreased in comparison to the previous week. Karangetang remained at Alert Level 2 (on a scale of 1-4).

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)