Mount Anak Krakatau entered a severe eruptive phase starting September 4, 2026, sending ash clouds up to 50,000 feet across five provinces and forcing the temporary shutdown of eight airports, according to Meteorology, Climatology, and Geophysics Agency (BMKG) Head Teuku Faisal Fathani. The latest activity marks a continuation of the Sunda Strait volcano’s century-long cycle of physical regeneration and destruction.
Origins from the 1883 Cataclysm
The history of Anak Krakatau traces back to the catastrophic eruption of ancient Krakatoa in August 1883. According to the Geological Agency of the Ministry of Energy and Mineral Resources (ESDM) and the Center for Volcanology and Geological Hazard Mitigation (PVMBG), that explosion collapsed three volcanic peaks named Perbuwatan, Danan, and Rakata. The event created a massive undersea caldera and triggered 30-meter tsunamis that killed over 36,000 lives, leaving a hollow magma chamber beneath the ocean floor.
After 44 years of dormancy, underwater activity resumed at the base of the caldera. Submarine eruptions began on December 29, 1927, ejecting jets of water and ash from a depth of 180 meters. Volcanic deposits accumulated until a new crater wall broke through the ocean surface, leading geological authorities to designate June 11, 1929, as the birth date of the island named Anak Krakatau.
Early Growth and Modern Eruptive Cycles
During its early building phase between 1931 and 1960, the young volcano recorded at least 47 separate eruptions. Seawater filled the crescent-shaped crater during this era to form a lake, which was eventually sealed off and buried by eruptive deposits by 1961.
Anak Krakatau entered one of its most active periods in modern history in November 1992, erupting almost daily with peak frequencies reaching up to one explosion every 15 minutes. Historical studies by the Geological Agency note that during active centuries, the volcano grew at an average rate of four meters per year. Active phases generally return at intervals of one to six years, alternating with periods of dormancy lasting one to eight years that allow internal pressure to accumulate.
Intensified Activity and Seismic Peaks
Volcanic activity intensified significantly between 2007 and 2009. The PVMBG raised the alert status to Level III in October 2007, and on November 9, 2007, the volcano recorded 182 individual eruptions in a single day. Incandescent lava streams cascaded down the slopes, and booming noises were heard at observation posts over 40 kilometers away.
Seismic activity reached a peak in October 2011, when the Smithsonian Institution recorded 5,883 daily seismic events at the volcano. Lava flows reached the sea during ensuing eruptions in September 2012, pushing the island’s coastline outward by 100 meters while hurling ash plumes 75 kilometers north to blanket Bandar Lampung.
The 2018 Flank Collapse and Tsunami
By September 2018, Anak Krakatau reached its highest recorded elevation at 338 meters above sea level. However, continuous eruptive pressure led to a catastrophic flank collapse on December 22, 2018.
According to National Disaster Management Agency (BNPB) records, the massive underwater landslide triggered a devastating tsunami along Banten and Lampung. The catastrophe claimed 437 lives and left upwards of 40,000 residents displaced, while the volcano lost two-thirds of its altitude to stand at just 110 meters.
Recent Restructuring and the September 2026 Escalation
Following its structural collapse, Anak Krakatau entered a new construction cycle. Bulletins from the Geological Agency documented a series of eruptions across 2022 and 2023, with ash columns rising as high as 1,000 meters above the rim of the crater. By late 2023, Magma Indonesia logged at least 85 distinct eruptive events, indicating that the volcano was actively rebuilding its body.
Following a brief lull, the volcano reawakened in July 2026 before culminating in the severe eruptive phase starting September 4, 2026. Teuku Faisal Fathani, head of the BMKG, stated that ash plumes climbed as high as 50,000 feet, spreading across five provinces and causing eight airports to temporarily suspend operations.