Mount Semeru Hiking Trails Closed as Volcano Erupts, Forest Fires Spread

Indonesia's Mount Semeru erupted on Sunday morning, September 6, 2026, spewing an ash column 1,000 meters high from its summit in East Java. The Bromo Tengger Semeru National Park reported that the eruption sent the volcanic material up to an altitude of 4,676 meters above sea level. The Mount Semeru Observation Post officer, Sigit Rian Alfian, confirmed the eruption had been recorded on seismographs with a maximum amplitude of 23 mm and a duration of 102 seconds.

Authorities have kept the hiking trails closed, citing safety concerns. The explosions have produced a hazardous environment, with pyroclastic flows, lava avalanches, and hot clouds posing threats to the area. The public has been warned to avoid the southeastern sector along the Besuk Kobokan River within 13 kilometers of the summit, where the eruption's epicenter was located.

Furthermore, activities are prohibited within 500 meters of the riverbanks and 5 kilometers of Mount Semeru's crater or summit due to the risk of incandescent rocks being ejected during eruptions.

The eruption has added to ongoing forest fires that have burned over 3,000 hectares of forest on the mountain's slopes. These fires have compounded the risk for hikers and firefighting efforts due to the difficult terrain and steep slopes. Earlier reports stated that 170 hikers were evacuated safely from Mount Semeru when the fires approached the main trekking route.

The hiking trails remain closed as part of the broader efforts to mitigate wildfire risks in Indonesia's national parks. The Ministry of Forestry announced temporary hiking restrictions in several national parks following fires affecting protected areas, including Mount Semeru. Authorities have urged the public to adhere to safety measures and steer clear of designated danger zones around the volcano.