Geology Agency Says Anak Krakatau’s Continuous Eruption Has Ended, Three Volcanoes Remain Active

A 25-hour episode of continuous eruption at Anak Krakatau has ended, but Indonesia’s Geology Agency says the volcano remains capable of erupting again. The agency said the episode began at 11:07 p.m. local time on September 4 and ended at 12:04 a.m. on September 6.

Afterward, the volcano returned to its strombolian pattern, marked by three recorded eruption earthquakes. The Geology Agency interpreted that shift as the end of the long-lasting continuous eruption phase, while warning that the probability of follow-up eruptions in the next period remained high.

Instrument readings from September 6 to 7 recorded three eruption earthquakes, nine blast earthquakes, 93 low-frequency earthquakes, 98 hybrid or multiphase earthquakes, four episodes of continuous tremor, and one shallow volcanic earthquake. The Real-time Seismic Amplitude Measurement graph, which rose sharply on September 5, began declining the following day. Tiltmeter data showed slight inflation at Tanjung Station since early August, while Lava93 Station recorded a constant pattern.

Based on its overall assessment, the agency kept Anak Krakatau at Level III, or Alert. Geology Agency chief Lana Saria recommended that residents, tourists, and hikers stay at least three kilometers from the active crater because of the risk of incandescent rock, hot clouds, lava flows, and heavy ashfall. Residents along the coasts of Banten and Lampung were urged to remain calm, reject hoaxes about a possible tsunami caused by the eruption, and wear masks outdoors to reduce exposure to volcanic ash.

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After the end of that episode, Anak Krakatau’s volcanic activity transitioned back to strombolian eruption characteristics, marked by the recording of three eruption or strombolian eruption earthquakes.