Lumajang, East Java (ANTARA) - Mount Semeru, located on the border of Lumajang and Malang Districts, East Java, experienced 45 eruption earthquakes over a six-hour period on Friday, from 12:00 a.m. to 6:00 a.m. local time.
"Seismic observations recorded 45 eruption earthquakes with amplitudes of 10-22 mm and durations of 58-184 seconds," an officer from the Mount Semeru Observation Post, Rudra Wibowo, said in a statement here on Friday.
The post also recorded six avalanche earthquakes from Mount Semeru with amplitudes of 2-4 mm and durations of 40-74 seconds, as well as eight gust earthquakes with amplitudes of 2-4 mm and durations of 34-69 seconds.
"Semeru also experienced five distant tectonic earthquakes with amplitudes of 4-8 mm, durations of 14-16 seconds, and durations of 25-53 seconds," Wibowo added.
According to him, visual observations of Mount Semeru showed a clear view, covered by 0-III level fog, with no crater smoke observed. The weather was cloudy to rainy, with light winds heading southeast.
Mount Semeru’s status remains at Level IV, or Warning, followed by several recommendations from the Center for Volcanology and Geological Hazard Mitigation (PVMBG), including prohibiting the public from engaging in any activities in the southeastern sector along Besuk Kobokan, within 20 km of the summit (the eruption center).
Beyond this distance, the public should not engage in activities within 500 meters of the riverbank along Besuk Kobokan due to the potential for expanding pyroclastic flows and lava flows.
"The public is also prohibited from engaging in activities within an 8-kilometer radius of the crater or peak of Mount Semeru due to the risk of ejected (incandescent) rocks," Wibowo said.
Authorities also warn of potential pyroclastic flows and cold lava along waterways descending from Mount Semeru’s summit—especially Besuk Kobokan, Besuk Bang, Besuk Kembar, Besuk Sat, and smaller streams feeding into Besuk Kobokan.
Earlier on Wednesday (November 19), Mount Semeru erupted at 04:00 p.m., with an eruption column reaching approximately 2,000 meters above the summit. During the eruption, Mount Semeru emitted a pyroclastic flow extending up to seven kilometers from the summit, with a thick gray ash column observed to the north and northwest.
The eruption, recorded on a seismogram at the Lumajang volcano monitoring post, had a maximum amplitude of 40 mm and a duration of approximately 16 minutes and 40 seconds.
