CVGHM reported that on 3 July an explosion of incandescent material from Soputan was followed by a 6-km-high ash plume and a pyroclastic flow that traveled as far as 4 km W. Later that day a dense white plume rose 50 m above the crater. On 20 July CVGHM noted that since 4 July seismicity had decreased and only diffuse white plumes rose 75 m above the crater until 18 July. The Alert Level was lowered to 2 (on a scale of 1-4) on 19 July. Visitors and residents were prohibited from going within a 4-km radius of the crater.

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.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)