An eruption lasting more than 24 hours at Anak Krakatau, the small volcano situated between the Indonesian islands of Java and Sumatra, sent gas and ash high into the atmosphere in early September 2026, forcing the temporary closure of eight airports and disrupting nearly 3,000 flights. The event began around September 5 and represented one of the more hazardous episodes in the volcano's otherwise frequently active history.
Indonesia's meteorological agency, BMKG, reported that ash had reached altitudes of up to 6,000 metres (20,000 feet) to the east of the volcano and 15,000 metres (50,000 feet) to the west by September 6. Satellite imagery captured during the eruption illustrated the scale of the dispersal: images from the NASA-USGS Landsat 8 satellite showed a white plume of volcanic gas billowing over a brown ash cloud, while a wider view from the Suomi NPP satellite's VIIRS instrument revealed volcanic material spreading across a large area.
Ashfall affected populated areas to the east of Anak Krakatau, including Jakarta and other parts of West Java. The Indonesian Humanitarian Coordination Platform (IHCP) reported that volcanic ash poses health risks, including irritation to the respiratory tract, eyes, and skin. The IHCP also noted that this air quality hazard differs from smoke produced by peatland fires elsewhere in Indonesia in terms of particle characteristics, dispersal patterns, and the protection measures required.
The continuous explosive eruption subsided on September 6, though the volcano continued to rumble and returned to a pattern of Strombolian eruptions — intermittent spurts of ash and volcanic material — consistent with its more typical behaviour. Airports had resumed operation by September 8, according to news reports, which also noted that around 340,000 passengers had been stranded during the closure period.
As of September 8, Anak Krakatau remained at the second-highest alert level on Indonesia's volcanic alert scale, a status it has held since early July.
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