According to VSI, on 15 July at 1355 an explosion at Karangetang's main crater produced an ash cloud to a height of 1.5 km above the crater. Ash fell to the N of the volcano. An accompanying lava avalanche traveled up to 1.5 km into Kahetang River Valley. During the rest of 15-21 July, low-level plumes continued to rise above Karangetang's main crater and Crater II. Based on information from a pilot report, the Darwin VAAC reported that a smoke plume was observed on 29 July at 1323 rising to an unknown height. 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.

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