PVMBG reported that during 4-11 April diffuse white plumes from Soputan rose as high as 100 m above the crater and drifted E. Seismicity was dominated by signals indicating avalanches and emissions; avalanche signals became less intense as compared to the previous week. A few volcanic and shallow volcanic earthquakes were detected during 6 and 9-10 April. The Alert Level was lowered to 2 (on a scale of 1-4); residents and tourists were advised not to approach the craters within a radius of 4 km. [Correction; the Alert Level remained at 3.]

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)