Volcanic activity at Mount Semeru, located on the border of Lumajang and Malang regencies, East Java, is reported to remain very high. The 3,676-meter-high volcano above sea level is still dominated by eruption earthquakes, with its activity level remaining at Level III (Standby).
Based on a written report by Mount Semeru Observation Post officer Liswanto, during the observation period on Thursday (16/7/2026) from 00:00 to 06:00 WIB, 15 eruption earthquakes were recorded. These earthquakes had amplitudes ranging from 13 to 22 millimeters and durations of 71 to 158 seconds. In addition, officers recorded five rockfall earthquakes, three gust earthquakes, one harmonic tremor, and two distant tectonic earthquakes.
The dominance of this seismic activity was also evident the previous day. Throughout Wednesday, monitoring instruments recorded 66 eruption earthquakes. On the same day, a pyroclastic flow occurred once with a duration of 187 seconds, followed by 16 rockfall earthquakes, 11 gust earthquakes, and eight harmonic tremors. Visually, Mount Semeru erupted seven times on Thursday morning, with ash columns ranging between 700 and 1,100 meters above the peak of the crater.
Given the high level of volcanic activity, authorities have issued strict safety recommendations for the public. Residents are strictly prohibited from conducting any activities in the southeastern sector along Besuk Kobokan up to 13 kilometers from the eruption center.
Beyond that radius, the public is also advised not to engage in activities within 500 meters of riverbanks along Besuk Kobokan due to the potential expansion of pyroclastic flows and lahar flows that could reach up to 17 kilometers. In addition, activities within a 5-kilometer radius of the active crater are prohibited to avoid the threat of incandescent material projection. Vigilance must also be heightened regarding the potential for cold lahars in other river basins such as Besuk Bang, Besuk Kembar, and Besuk Sat.
