"Activity started on 30 July [1985] from the main summit crater (Doro Api . . .). At about 0900 a thick plume rose to 3,500 m height. The eruption continued with explosions at 1130 (6,500 m), 1320 (6,500 m) and 1800 (1,500 m). About 2 mm of ash fell in Bima, 50 km SW of the volcano. Between then and 5 August explosions occurred every 30-60 minutes. Black plumes reached 2,000-2,500 m height. On 6 August at 1939 lava was observed flowing W from Doro Api crater. At the end of September the lava flow had advanced ~4,750 m. Numerous explosions took place from September to November, producing columns ~400-500 m high. On 17 November an explosion ejected incandescent lava fragments to ~250 m height and a plume rose to 1,200 m above the crater [see also 10:7-12]. During December and January, gas explosions, sometimes accompanied by ejection of incandescent lava fragments, averaged ~80 events/day. The 1,242 inhabitants of the island were evacuated to the main island of Sumbawa. There were no casualties."

Geological Summary. Sangeang Api volcano, one of the most active in the Lesser Sunda Islands, forms a small 13-km-wide island off the NE coast of Sumbawa Island. Two large trachybasaltic-to-tranchyandesitic volcanic cones, Doro Api and Doro Mantoi, were constructed in the center and on the eastern rim, respectively, of an older, largely obscured caldera. Flank vents occur on the south side of Doro Mantoi and near the northern coast. Intermittent eruptions have been recorded since 1512, most of them during in the 20th century.

Information Contacts: A. Sudradjat, VSI.