Indonesia’s Mount Semeru remains at Alert Level III as of January 16, 2026, indicating continued high volcanic activity at the East Java volcano located in Lumajang. The Geological Agency is maintaining this alert level due to ongoing pyroclastic flows originating from the peak.
Recent Activity
Pyroclastic Flows
Pyroclastic flows were reported on Thursday, January 15, extending up to 4 kilometers from the summit. Prior to that, on Wednesday, January 14, two pyroclastic flows reached distances of 5 kilometers. These flows have been primarily moving in a southeast direction toward Besuk Kobokan. Between January 7 and January 14, several pyroclastic flows occurred, with the longest reaching 5 kilometers, accompanied by material avalanches.
Seismic Activity
Seismic activity at Semeru is characterized by eruption, avalanche, and blast earthquakes, as well as harmonic tremors. According to Acting Head of the Geological Agency, Lana Saria, this seismic activity suggests an active magma supply beneath the volcano, releasing material through eruptions and blasts.
Current Recommendations
The Geological Agency recommends that communities, visitors, and climbers avoid activities within a 5-kilometer radius of Kawah Jonggring Seloko. Entry is prohibited in the southeast sector up to 13 kilometers from the peak, extending to 17 kilometers along the Besuk Kobokan flow path. Authorities are urging vigilance against pyroclastic flows, lava avalanches, and lahars along rivers and valleys originating from the volcano’s peak.
Seismic Data
Seismic monitoring conducted by the Semeru Volcano Observation Post (PGA) in Lumajang, over the six hours leading up to 06:00 AM local time on Friday, recorded 37 eruption earthquakes, two avalanche earthquakes, three blast earthquakes, and one harmonic tremor.
What Could Happen Next
The Geological Agency continues to closely monitor Mount Semeru. Should seismic activity increase, or deformation patterns change, the alert level could be raised. It is possible that further pyroclastic flows could occur, potentially impacting areas within the exclusion zones. Continued monitoring will be crucial to assess any changes in the volcano’s behavior.
Frequently Asked Questions
What is Alert Level III?
Alert Level III signifies that the volcano shows increased volcanic activity. The Geological Agency maintains this level when pyroclastic flows are occurring and there is a potential for further eruptions.
Where are the primary hazards located?
The primary hazards are located in the southeast sector of the volcano, extending up to 17 kilometers along the Besuk Kobokan flow path. Areas within a 5-kilometer radius of Kawah Jonggring Seloko are also considered high-risk.
What types of earthquakes have been detected?
Seismic activity has been dominated by eruption, avalanche, and blast earthquakes, along with harmonic tremors, indicating an active magma supply beneath the volcano.
Given the ongoing activity at Mount Semeru, what measures do you think are most important for local communities to take to ensure their safety?
