Mount Semeru Emits Hot Clouds for Two Days, Alert Level Remains High

January 16, 2026 | 09:30 am

TEMPO.CO, Jakarta - Indonesia’s Geological Agency has maintained Mount Semeru’s volcanic activity at Level III (Alert) as of Friday, January 16, 2026, signaling continued high activity at the East Java volcano in Lumajang.

The alert comes amid repeated pyroclastic flows from the peak.

Acting Head of the Geological Agency, Lana Saria, reported that pyroclastic flows occurred again on Thursday, January 15, traveling up to 4 kilometers from the summit.

The day before, the flows occurred twice, reaching distances of 5 kilometers. The flows have been primarily directed toward the southeast sector, in the direction of Besuk Kobokan.

Between January 7–14, the volcano produced several pyroclastic flows with the farthest sliding distance recorded at 5 kilometers, accompanied by material avalanches.

Seismic activity at Semeru has been dominated by eruption, avalanche, and blast earthquakes, along with harmonic tremors.

According to Lana, these earthquakes indicate an active magma supply beneath the volcano, with material being released to the surface through eruptions and blasts.

“Seismic velocity measurements show fluctuations with significant deviation, indicating that the volcanic system is in a relaxation phase rather than pressurization, but it remains highly susceptible to increased pressure,” Lana explained.

She added that deformation monitoring shows a relatively stable pattern, suggesting no current pressure buildup inside the volcano.

Based on the evaluation, the agency recommends that communities, visitors, and climbers avoid activities within a 5-kilometer radius of Kawah Jonggring Seloko.

Entry is also prohibited in the southeast sector up to 13 kilometers from the peak, which can extend to 17 kilometers along the Besuk Kobokan flow.

Authorities have urged vigilance against pyroclastic flows, lava avalanches, and lahars along rivers and valleys originating from the peak.

Seismic monitoring from the Semeru Volcano Observation Post (PGA) in Lumajang over the six hours leading to Friday at 06:00 AM local time recorded 37 eruption earthquakes with amplitudes of 13–22 mm and durations of 72–118 seconds, two avalanche earthquakes measuring 4–8 mm lasting 56–73 seconds, three blast earthquakes with amplitudes of 6–7 mm and durations of 42–55 seconds, and one harmonic tremor measuring 9 mm with a duration of 87 seconds.

The Geological Agency continues to closely monitor Mount Semeru and will provide updates as conditions evolve.

Read: Volcanic Activity at Indonesia's Mount Semeru Remains High

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