Report on Soputan (Indonesia) — 16 July-22 July 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
16 July-22 July 2003
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2003. Report on Soputan (Indonesia). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 16 July-22 July 2003. Smithsonian Institution and US Geological Survey.
1.112°N, 124.737°E; summit elev. 1785 m
All times are local (unless otherwise noted)
High levels of volcanic and seismic activity occurred at Soputan during mid-July. On 17 July at 1900 the Alert Level was raised to 2 (on a scale of 1-4) after incandescence was seen at the lava dome for about a day. Around 1150 the amplitude of volcanic tremor increased and at 1900 an increased level of incandescence was seen. On 18 July at 0630 incandescent lava avalanches suddenly occurred that were not proceeded by explosions or loud sounds. The avalanches were accompanied by a pyroclastic surge towards the WNW and an ash cloud that rose ~2 km above the summit. The cloud drifted N, depositing ash around the area of Tombasian, Tareran, Tompaso, Kawangkoan, Sonder, Tomohon, and Manado. The same day the Alert Level was raised to 3. On 19 July there were pyroclastic flows, ash explosions, Strombolian activity, and lava emission at the lava dome. Ash explosions continued through at least 21 July. According to news reports, some residents in villages near the volcano fled, including those in the villages of Kota Menara, Amurang, and Maliku around 10 km S of the volcano.
Geological Summary. The Soputan stratovolcano on the southern rim of the Quaternary Tondano caldera on the northern arm of Sulawesi Island is one of Sulawesi's most active volcanoes. The youthful, largely unvegetated volcano is the only active cone in the Sempu-Soputan volcanic complex, which includes the Soputan caldera, Rindengan, and Manimporok (3.5 km ESE). Kawah Masem maar was formed in the W part of the caldera and contains a crater lake; sulfur has been extracted from fumarolic areas in the maar since 1938. Recent eruptions have originated at both the summit crater and Aeseput, a prominent NE-flank vent that formed in 1906 and was the source of intermittent major lava flows until 1924.