Anak Krakatau Activity Eases, but Eruption Risk Remains High: Govt

RRI.CO.ID, Jakarta - Activity at the Anak Krakatau volcano has begun to subside after a continuous eruption lasting about 25 hours. However, the Geological Agency of the Ministry of Energy and Mineral Resources continues to maintain the volcano’s status at Level III (Alert).

The change in activity occurred after the continuous eruption episode from September 4–6, 2026, ended. Since then, surface activity has gradually decreased and shifted to Strombolian eruptions.

Head of the Geological Agency, Lana Saria, explained that Strombolian eruptions are a characteristic feature of Anak Krakatau’s activity. Based on observations through Friday, September 11, at 6 a.m. Jakarta Time, 14 Strombolian eruptions were recorded.

“The resumption of Strombolian eruptions indicates that the continuous eruption episode has ended. However, volcanic activity is still ongoing, so the public must remain cautious and comply with the established recommendations,” Lana said in a written statement on Friday.

Strombolian eruptions are periodic bursts caused by the release of gas from magma. This activity can eject incandescent material and volcanic ash around the crater.

Monitoring data shows that low‑frequency and hybrid (multi‑phase) earthquakes continue to fluctuate with a downward trend. However, volcanic earthquakes have been recorded at levels higher than the average for Anak Krakatau.

This increase in deep volcanic earthquakes indicates that magma movement or supply from deeper layers is still occurring. These conditions mean the risk of another eruption remains high even as surface activity decreases.

The Geological Agency ensures that monitoring of Anak Krakatau continues using equipment that remains operational. Observations also include visual monitoring and other parameters to assess volcanic activity.

“Monitoring of Anak Krakatau will continue as usual. Data from available equipment is continuously received and analyzed to assess activity levels and inform recommendations,” Lana said.

The Agency is also preparing to inspect, repair, and replace equipment damaged by the eruption. “Personnel safety is a priority. Additional personnel will only be deployed once conditions allow and all safety procedures have been met,” she said.

With Level III status in effect, the public, tourists, fishermen, and those engaged in maritime activities are advised to avoid any activity within a 3‑kilometer radius of the active crater. Potential hazards include ejection of incandescent material, volcanic ash, and possible hot ash clouds.

Residents affected by ashfall are advised to wear masks, protect their eyes, and cover fresh water sources.

“Given that Krakatau is an active volcano, a decrease in the intensity of surface eruptions does not mean Anak Krakatau’s eruptive activity will cease. Stay alert, observe the recommended safety radius, and follow official information,” Lana said.

The Geological Agency also urges the public to remain calm and avoid unverified information. Updates on Anak Krakatau are available through the official channels of the Geological Agency and MAGMA Indonesia. (Gusti Panji)