Major eruption at Semeru volcano produces large pyroclastic flow, ash to 16.5 km (54 000 feet) a.s.l., Indonesia
A major eruption took place at Semeru volcano, Indonesia, on November 19, 2025, producing large pyroclastic flow and ash column up to 16.5 km (54,000 feet) above sea level. The Aviation Color Code was raised to Red while authorities issued exclusion zones along Besuk Kobokan.
Large pyroclastic flow produced during major eruption at Semeru volcano on November 19, 2025. Credit: PVMBG
Satellite data from JMA’s Himawari-8 showed a rapidly intensifying ash column during the morning hours, with the Darwin Volcanic Ash Advisory Centre (VAAC) confirming ash reaching approximately 16.5 km (54 000 feet) above sea level (a.s.l.) at 09:20 UTC (16:20 WIB).
Although the plume was partially obscured by meteorological cloud, infrared analysis indicated continuous emissions from the summit crater and dispersal toward the north and northwest.
Ground observations confirmed the generation of a large pyroclastic density current (PDC) moving through the southeastern drainage network. The flow followed the Besuk Kobokan valley, which has historically acted as the primary channel during major eruptive episodes at Semeru.
Local CCTV recordings and community livestreams documented the propagation of low-lying, ash-rich pyroclastic density currents (PDCs) throughout the afternoon. According to early local observations, PDC activity initiated at approximately 14:30 WIB (07:30 UTC), with runout distances reaching at least 5 km (3.1 miles) by 15:00 WIB (08:00 UTC).
Subsequent field reports indicated that later PDC pulses may have extended to distances of up to 15 km (9.3 miles) along the southeastern drainage system.
Time-lapse of Semeru erupting. I think it's still erupting…
— Volcaholic (@volcaholic1) November 19, 2025
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PVMBG issued hazard advisories for areas surrounding the volcano, maintaining an 8 km (5 miles) exclusion zone along Besuk Kobokan and recommending that residents avoid activity within 500 m (1 640 feet) of riverbanks beyond that distance due to the risk of expanding PDCs and lahar flows.
A 2.5 km (1.5 miles) exclusion radius around the summit remained enforced because of ballistic ejecta hazards associated with ongoing eruptive activity. Additional warnings applied to valleys draining the upper cone, including Besuk Bang, Besuk Kembar, Besuk Sat, and tributaries of Besuk Kobokan.
Eruptive activity continued into the late afternoon, with persistent ash emissions and elevated hazard conditions across the southern and southeastern sectors of the volcano.
Teo Blašković founded The Watchers in 2011 and edited it until 2026, covering seismic and volcanic activity, extreme weather, space weather and near-Earth objects. Articles on this page are his archive.
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