Mount Anak Krakatau Returns to Alert Level II

September 22, 2026 | 10:50 am

TEMPO.CO, Jakarta - The level of activity at Mount Anak Krakatau has been downgraded to Level II (Alert) starting from today, Monday, September 21, 2026, at 18:30 WIB (Western Indonesia Time). On July 2, the volcanic mountain in the Sunda Strait was raised to Level III (Standby), and it has continued to erupt, spewing ash across West Java and West Sumatra.

According to Special Report Number: 1604.Lap/GL.03/BGL/2026 released by the Head of the Geological Agency Lana Saria, Mount Anak Krakatau experienced 224 eruptions throughout the Standby status until September 3. From September 4 at 23:07 WIB to September 6, 2026, at 00:04 WIB, continuous eruptions occurred for 25 hours.

Satellite imagery showed continuous eruptions produced lava flows moving northwest, west, and southwest from the eruption center. Volcanic ash reached Greater Jakarta, forcing air transportation authorities to close several airports, including Soekarno-Hatta International Airport, to ensure flight safety.

Lana explained that despite still emitting seven strombolian eruptions, the activity of Mount Anak Krakatau tends to decrease after the cessation of continuous eruptions until September 20 at 00:00 WIB. "In addition, the symptom of decreasing volcanic activity is supported by deformation data showing deflation."

Seismic records of Mount Anak Krakatau on September 20, 2026, showed one low-frequency earthquake. The continuous tremor amplitude also averaged only 2 mm.

Nevertheless, Lana reminded that the community around Mount Anak Krakatau, as well as visitors or tourists, are still not allowed to enter and carry out activities within the volcano's area. The safe radius is two kilometers from the center of Mount Anak Krakatau's activity. This is a one-kilometer decrease from the standby status.

"The level of Mount Anak Krakatau's volcanic activity will be periodically re-evaluated, or if there are significant changes in activity," Lana added.

Read: End of Search for Missing Journalists in Sunda Strait: What to Know

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