RRI.CO.ID, Lumajang - Mount Semeru, located on the border of Lumajang and Malang Regencies in East Java, erupted five times on Monday morning, August 3, 2026, generating ash columns ranging between 300 meters and 700 meters above its peak.

According to reports from the Mount Semeru Observation Post, the eruptions began at 12.18 a.m. local time with a 500-meter ash column, followed by a second eruption at 12.31 a.m. local time reaching 700 meters.

Subsequent eruptions occurred at 1.46 a.m. local time (600 meters), 5.50 a.m. local time (300 meters), and 7.56 a.m. local time (700 meters). The final morning eruption recorded a maximum amplitude of 22 mm on seismographs with a duration of 120 seconds, dispersing thick white-to-gray ash plumes toward the southeast.

Mount Semeru remains under Level III (Alert) status. Geological authorities have enforced a strict exclusion zone, prohibiting all activities along the Besuk Kobokan sector within 13 kilometers of the summit and extending buffer zones along riverbanks to mitigate risks from potential hot clouds, lava flows, and cold lava floods (lahar).

Volcanologists and monitoring officials reiterated safety advisories, urging local residents to strictly comply with danger zone boundaries to prevent casualties during heightened volcanic activity. Mount Semeru Observation Post Officer Liswanto detailed the mandatory exclusion parameters and potential secondary hazards.

"People are prohibited from conducting activities within a five-kilometer radius from the crater or peak of Mount Semeru due to susceptibility to glowing rock ejection hazards," Liswanto reported in a written statement received in Lumajang on Monday, August 3, 2026, as quoted by Antara.

He also warned communities surrounding river channels originating from the volcano to remain vigilant against secondary hazards.

"Beyond that distance, the public must not engage in activities within 500 meters of riverbanks along Besuk Kobokan, as they are potentially subject to the expansion of pyroclastic flows and lahar flows up to a distance of 17 kilometers from the peak, we advise the public to stay alert for potential hot clouds, lava falls, and lahar along river courses and valleys originating at the peak of Mount Semeru, particularly along Besuk Kobokan, Besuk Bang, Besuk Kembar, and Besuk Sat, as well as tributaries of Besuk Kobokan," Liswanto explained. ***