Geology agency warns Anak Krakatau activity could fluctuate and intensify

Anak Krakatau’s activity has increased, with eruptions occurring repeatedly and continuously, Indonesia’s Geological Agency said. The agency warned that activity could continue to fluctuate and intensify, although it said the current pattern did not automatically signal a larger eruption.

Lana Saria, head of the Geological Agency at the Energy and Mineral Resources Ministry, said the increase reflected continued magma and gas supply inside the volcano. The agency is evaluating all available monitoring data, rather than relying only on the number or height of eruption columns.

Activity began rising again in July 2026. On July 2, authorities raised the volcano’s status from Level II, or Alert, to Level III, or Standby. The highest activity recorded so far came on September 5. At 11 p.m. local time on September 4, Anak Krakatau entered a continuous eruption accompanied by lava fountains, rumbling and booming sounds.

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Anak Krakatau is indeed more active now than in the previous period, marked by eruptions that are repeated and continuous.

Saria said low-frequency, hybrid and harmonic earthquakes, along with tremors, were still being recorded. “The types of earthquakes indicate the movement or release of volcanic fluids within the volcanic system,” she said.

Authorities said they could not precisely determine the timing, size or form of the next eruption. They urged residents and tourists to stay outside a three-kilometre radius from the centre of activity, remain alert to volcanic hazards and wear masks if ash affects their area. The agency also urged the public to rely on official government information rather than untrusted reports.

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The types of earthquakes indicate the movement or release of volcanic fluids within the volcanic system.