Eruptive activity at Karangetang since the previous report (BGVN 25:12) continued through 5 February 2001. A minor explosion occurred at 2227 on 25 January and produced an ash-heavy plume that rose 700 m; ash fell into the sea W of the volcano. The eruption also featured a molten lava avalanche that flowed down to the Kelitu River with a maximum runout distance of ~1,250 m from the summit. At 2109 on 28 January a second, Strombolian-style explosion occurred that sent glowing ejecta 300 m above the crater; a black ash cloud rose 1 km and ashfall was observed on a nearby beach. The 28 January eruption also sent lava avalanches ~1,500 m down Karangetang's W flank. Seismicity for the period 23-29 January was dominated by multi-phase earthquakes.

During 30 January-5 February no significant visual activity was observed; multi-phase earthquakes outnumbered all others during the week. VSI maintained a hazard status of 2 (on a scale of 1-4) for Karangetang, and no further eruptive episodes were 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.

Information Contacts: Dali Ahmad, Volcanological Survey of Indonesia (VSI), Jalan Diponegoro No. 57, Bandung 40122, Indonesia (URL: http://www.vsi.esdm.go.id/).