September 21, 2026 | 11:47 pm
TEMPO.CO, Jakarta - The volcanic activity level of Mount Anak Krakatau has been lowered to Alert Level II on Monday, September 21, 2026, at 6:30 p.m. Jakarta time. The volcano in the Sunda Strait was raised to Alert Level III on July 2 and has been continuously erupting, spewing ash that spread as far as West Java and West Sumatra.
The Head of the Geological Agency, Lana Saria, explained that Mount Anak Krakatau experienced 224 eruptions until September 3. The volcano also recorded continuous 25-hour eruptions from September 4 at 11:07 p.m. to September 6 at 12:04 a.m.
Based on satellite imagery, these continuous eruptions produced lava flows that flowed northwest-west-southwest from the eruption center. The volcanic ash reached Greater Jakarta and forced authorities to close several airports, including Soekarno-Hatta International Airport, for flight safety reasons.
Despite still emitting seven Strombolian eruptions, Mount Anak Krakatau's activity has slowed after the continuous eruptions stopped as of 12:00 a.m. on September 20. "This is supported by deformation data showing a deflation."
Seismicity records for Mount Anak Krakatau on September 20, 2026, showed one low-frequency earthquake. The amplitude of the continuous tremors also averaged only 2 mm.
Nevertheless, Lana warned residents around Mount Anak Krakatau, visitors, tourists, or climbers, that they are still not permitted to enter or conduct activities near the volcanic area or within a 2-kilometer radius from the crater.
"The activity level of the Anak Krakatau volcano will be re-evaluated periodically, or if there is a significant change in activity," Lana added.
Read: How BRIN Simulates Paths of Journalists Missing Near Anak Krakatau
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