Mount Semeru activity remains dominated by explosive eruptions
Lumajang, East Java (ANTARA) - Mount Semeru, which stands at 3,676 metres above sea level on the border of Lumajang and Malang districts in East Java, remains dominated by volcanic activity in the form of explosive earthquakes/eruptions over the six hours to Wednesday.
“During observations from 00:00 to 06:00 WIB on Wednesday, Mount Semeru recorded 12 explosive/eruptive earthquakes with amplitudes of 10-19 mm, and quake durations of 58-99 seconds,” said Sigit Rian Alfian, an Officer at the Mount Semeru Observation Post, in a written report received in Lumajang.
In addition to explosive earthquakes, one rockfall earthquake was recorded with an amplitude of 2 mm and a duration of 40 seconds, followed by 13 harmonic/embalo? (Hembusan) earthquakes with amplitudes of 3-7 mm and durations of 46-61 seconds, as well as one distant tectonic earthquake with an amplitude of 16 mm, S-P 14 seconds and quake duration 39 seconds.
“For visual observation, the volcano is shrouded by fog from 0-I to 0-II. The crater plume was not observed. The weather is cloudy to overcast, with light winds from the northeast,” he said.
“There was an eruption of Mount Semeru on Wednesday, 4 March 2026, at 08:40 WIB, with no eruption visible. The eruption was recorded on the seismograph with a maximum amplitude of 22 mm and duration of 147 seconds,” he added.
He explained that Mount Semeru is at Level III (Siaga) status, so the Centre for Volcanology and Geological Hazard Mitigation (PVMBG) issued several recommendations: the public must not engage in any activity in the southeast sector along Besuk Kobokan, up to 13 kilometres from the summit (eruption centre).
Beyond that distance, the public must not operate within 500 metres of the riverbank along Besuk Kobokan because of the potential for expansion of hot clouds and lava flows up to 17 kilometres from the summit.
“The public is also forbidden to engage in activities within a 5-kilometre radius of the crater/summit of Mount Semeru due to risk of lava bombs (pijar),” he said.
The public should remain vigilant for potential ash clouds, lava flows, and lahars along river valleys that originate from the summit of Mount Semeru, especially along Besuk Kobokan, Besuk Bang, Besuk Kembar, and Besuk Sat, as well as lahars in small rivers that are tributaries of Besuk Kobokan.