Disaster

Mount Semeru Erupts Three Times Today, Plume Hits 1 Km

Stateline MEDIA Newsroom•October 17, 2026•3 min read

Mount Semeru erupted three times on Saturday, sending ash plumes up to 1,000 meters. PVMBG maintains Level III alert and bans activities within 13 km of crater.

Key Facts

Tiga erupsi tercatat pada Sabtu (17/10/2026): pukul 04.52 WIB dengan kolom letusan 700 meter, pukul 06.35 WIB dengan kolom 800 meter (setara 4.476 mdpl), dan pukul 10.42 WIB dengan kolom 1.000 meter.
Erupsi pukul 06.35 terekam di seismogram dengan amplitudo maksimum 25 mm dan durasi sekitar 1 menit 30 detik; erupsi pukul 10.42 berdurasi 137 detik dengan amplitudo maksimum 25 mm.
Kolom abu berwarna putih hingga kelabu dengan intensitas tebal dan condong ke arah barat. Delapan letusan lain berkolom 400-600 meter serta guguran lava pijar sejauh 1,5 kilometer ke arah tenggara menuju Besuk Kobokan juga teramati hari ini.
Status aktivitas vulkanik Gunung Semeru berada pada Level III (Siaga).
PVMBG melarang aktivitas di sektor tenggara sepanjang Besuk Kobokan hingga 13 kilometer dari puncak, dalam radius 5 kilometer dari kawah karena bahaya lontaran batu pijar, serta 500 meter dari tepi sungai karena potensi perluasan awan panas dan aliran lahar hingga 17 kilometer dari puncak.
Potensi bahaya meliputi awan panas guguran dan banjir lahar di aliran sungai yang berhulu di puncak Semeru: Besuk Kobokan, Besuk Bang, Besuk Kembar, dan Besuk Sat.

Three Eruptions in a Single Day

Mount Semeru on the border of Lumajang and Malang Regencies, East Java, erupted three times on Saturday (17/10/2026). The first eruption occurred at 04:52 WIB (Western Indonesia Time) with an ash column approximately 700 meters high, accompanied by thick gray volcanic ash.

A second eruption followed at 06:35 WIB, with the column height rising to about 800 meters above the peak, or 4,476 meters above sea level. The Center for Volcanology and Geological Hazard Mitigation (PVMBG) noted that this eruption was recorded on the seismogram with a maximum amplitude of 25 millimeters and lasted approximately 1 minute and 30 seconds.

Peak activity occurred during the third eruption at 10:42 WIB, with an eruption column reaching 1,000 meters above the summit. This eruption was recorded on the seismograph lasting 137 seconds with a maximum amplitude of 25 mm. "The ash column was observed to be white to gray with thick intensity leaning towards the west," wrote PVMBG in its written statement.

Incandescent Lava Flows 1.5 Kilometers Toward Besuk Kobokan

In addition to the three main eruptions, Semeru's activity today was also marked by eight smaller eruptions producing ash columns around 400 to 600 meters above the summit. Thick gray smoke was observed drifting toward the east during some of these events.

Mount Semeru Observation Post officer Liswanto reported observing incandescent lava avalanches traveling 1.5 kilometers southeast toward Besuk Kobokan. "Mount Semeru released incandescent lava avalanches with a runout distance of 1,500 meters heading Southeast," he stated in a written report. Officials urged residents to increase vigilance against potential pyroclastic flows and lahar floods.

Alert Status and Activity Prohibitions

As of Saturday night, the volcanic activity status of Mount Semeru remains at Level III or Alert (Siaga). PVMBG has enforced activity restriction recommendations, especially in the southeastern sector and along the Besuk Kobokan river flow prone to volcanic materials.

The public is prohibited from conducting activities in the southeastern sector along Besuk Kobokan up to 13 kilometers from the eruption center. Residents are also asked to stay at least 500 meters away from the riverbanks along Besuk Kobokan due to the potential expansion of pyroclastic density currents and lahar flows up to 17 kilometers from the summit.

Furthermore, activities within a five-kilometer radius of the crater are forbidden to prevent the threat of incandescent rock projectiles. Volcanic hazards also encompass rivers and valleys originating from Semeru's peak, namely Besuk Kobokan, Besuk Bang, Besuk Kembar, and Besuk Sat, as well as small tributaries flowing into Besuk Kobokan.

PVMBG Advisories for Residents

PVMBG urged people living in disaster-prone areas to comply with officer recommendations and monitor official updates regarding Mount Semeru's activity. Vigilance must be maintained, particularly in areas potentially affected by volcanic materials and lahar flows.

Residents living near river basins are asked to refrain from activities in danger zones and immediately evacuate if activity escalates, including heavy ashfall or rumbling sounds from the summit.