Volcanic activity at Mount Semeru, located on the border of Lumajang and Malang Regencies, East Java, is reported to remain very high and dominated by eruption earthquakes. To date, the highest mountain on Java Island still holds Level III or Alert status, as active magma supply to the surface continues to be monitored.
According to data from the Mount Semeru Observation Post on Thursday (16/7/2026) between 00:00 and 06:00 WIB, 15 eruption earthquakes were recorded. These earthquakes had amplitudes ranging from 13 to 22 millimeters with durations between 71 and 158 seconds.
In addition to eruption earthquakes, observation post officers also recorded other seismic activity, including five rockfall earthquakes, three emission earthquakes, one harmonic tremor, and two distant tectonic earthquakes. Visually, the 3,676-meter-high volcano above sea level produced ash columns reaching 700 to 1,100 meters above the peak during seven visual eruptions in that six-hour period.
This high volcanic activity aligns with records from the previous day. Throughout Wednesday (15/7), officers recorded a massive series of activity comprising 66 eruption earthquakes, one pyroclastic flow avalanche, 16 rockfall earthquakes, as well as several emission and harmonic earthquakes. This seismic series confirms that the potential for subsequent eruptions remains high.
In response to this situation, the Center for Volcanology and Geological Hazard Mitigation (PVMBG) requested local residents to comply with safety recommendations. Residents are strictly prohibited from conducting any activities in the southeastern sector along Besuk Kobokan, up to a clear distance of 13 kilometers from the active crater center.
Furthermore, PVMBG advised the public not to conduct activities within a 500-meter radius of the riverbanks along Besuk Kobokan to avoid the risk of expanding pyroclastic flows and cold lahar flows, which could potentially travel up to 17 kilometers. A sterile zone also applies within a five-kilometer radius from the summit of Semeru to avoid the danger of incandescent rock projections.
Authorities reminded the public to remain vigilant against secondary disaster risks such as lava avalanches and rain-triggered lahar floods in rivers originating from Mount Semeru, including Besuk Bang, Besuk Kembar, and Besuk Sat. The public is urged to continue following official information updates from relevant agencies.
