According to DVGHM, volcanic tremor at Soputan began to increase to levels above normal on 18 October at 0930. In response, officials raised the Alert Level to Orange or 2 (on a scale of 1-4). Soputan erupted on 18 October at 1041, producing an E-drifting ash cloud to a height of ~600 m above the volcano's crater. At 1815 incandescence was visible reflecting 25-30 m above the crater's rim. Later that day, a "lava avalanche" traveled towards the S.

According to a news report, "ash and smoke" covered several parts of the nearby Minahasa regency and damaged hundreds of plantations along the mountain's slopes. Also, clouds of ash disrupted activities of residents in W Langowan district, where visibility fell to between 10 and 30 m. An official in the district said local homes were covered by up to 4 cm of ash. In the town of Palu, visibility decreased to 7 km. No evacuations were ordered.

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.

Sources: Agence France-Presse (AFP), Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM), The Jakarta Post