Semeru eruption sends pyroclastic flow 3.5 km (2.2 miles) down Besuk Kobokan, Indonesia
An explosive eruption occurred at Semeru volcano in East Java, Indonesia, at 08:49 LT (01:49 UTC) on March 29, 2026, producing an ash plume rising 800 m (2 625 feet) above the summit and a pyroclastic density current traveling 3.5 km (2.2 miles) toward the Besuk Kobokan drainage.
The eruption lasted approximately 4 minutes and 6 seconds and was recorded with a maximum seismic amplitude of 22 mm. Observations from the Semeru Volcano Observation Post indicate that this event was part of a sequence of eruptive activity, with multiple eruptions recorded earlier the same day.
The pyroclastic density current (PDC) represents the most significant hazard element of the eruption, as PCDs consist of hot gas, ash, and volcanic material moving rapidly downslope through established drainage channels. The reported runout distance of 3.5 km (2.2 miles) followed the Besuk Kobokan drainage — a known pathway for PDCs during Semeru’s eruptive phases.
The Darwin Volcanic Ash Advisory Centre reported ash clouds reaching approximately 4.6 km (15 000 feet) above sea level, drifting west-northwest to northwest.
Indonesia’s Center for Volcanology and Geological Hazard Mitigation (PVMBG) maintains Alert Level 3 on a four-level scale.
An exclusion zone of 5 km (3.1 miles) from the summit remains in effect, as well as extended restrictions up to 13 km (8 miles) along the southeast sector following the Besuk Kobokan drainage. Additional buffer zones are applied along river systems due to the risk of lahars and remobilized volcanic material.
Featured image: Eruption at Semeru volcano on March 29, 2026. Credit: afarTV (stillshot)
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