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Indonesia volcanic activity September-October 2026

Updated 11 times since CLSTR started tracking revisions of this situation.

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2026-09-29 16:11 UTC → 2026-10-06 03:06 UTC · added ~~removed~~

Indonesia volcanic activity ~~September~~ September-October 2026

Indonesia’s volcanic activity intensified through August and early September 2026. Between August 18 and 20, Mount Ibu, Mount Lewotobi Laki-laki, and Mount Semeru all experienced eruptions. Mount Ibu was placed at Level II (Alert), while Lewotobi Laki-laki and Semeru were at Level III (Standby). On August 27, Mount Lewotobi Laki-laki erupted, producing a 2,500-meter ash column. On September 6, Mount Ibu experienced multiple eruptions, and Mount Semeru produced a 1,000-meter ash column. Semeru remains at Level III (Siaga), with a 5 km radius exclusion zone and a 13 km sector restriction along Besuk Kobokan. Activity expanded on September 7, when Gunung Ile Lewotolok in East Nusa Tenggara experienced two eruptions with 600-meter ash columns, placing it at Level II (Waspada) with a 2 km exclusion zone. Additionally, Gunung Merapi recorded 14 lava flows toward the southwest, reaching distances of 2,000 meters, while remaining at Level III (Siaga). As multiple volcanoes—including Anak Krakatau, Dukono, and Sinabung—report eruptions, officials from the Geological Agency and BRIN clarified that these simultaneous events are natural phenomena of the Pacific Ring of Fire. The government is monitoring potential disruptions to aviation cargo and logistics. Meanwhile, health officials are emphasizing disaster preparedness to manage respiratory risks posed by volcanic ash. On September 8, Lewotolok erupted again, sending ash and material toward residential areas. Residents reported lava flows approaching traditional villages and gardens within 200 to 300 meters. Concurrently, eruptions at Anak Krakatau forced the temporary suspension of hundreds of flights at Jakarta’s main airport. The national volcanic agency has prohibited all activities within a 3 km radius of Lewotolok and advised the use of masks due to declining air quality. By September 9, the Geological Agency recorded eruptions from 11 active volcanoes throughout 2026. On September 27, Mount Semeru experienced four eruptions between 00:21 and 06:22 WIB.

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