Mount Sinabung Activity Increases, Deep Volcanic Earthquakes Detected

Mount Sinabung (2,451 metres above sea level) in Karo Regency, North Sumatra, has shown an increase in activity. The Sinabung Monitoring Post reported that seismic activity at the volcano is currently dominated by tectonic and volcanic earthquakes, although the numbers are not significant. Head of the Sinabung Monitoring Post, Armen Putra, stated that monitoring over the weekend of 1 August 2026 recorded an increase in deep volcanic earthquakes. “In addition, we also recorded blast earthquakes, low-frequency earthquakes, and hybrid earthquakes, which were previously rarely recorded,” Armen said on Monday (3 August). According to Armen, crater smoke emissions were observed as thin to moderate white plumes, reaching heights of 50 to 600 metres above the lava dome. “This increase in seismic activity needs to be watched, considering the potential hazards of Mount Sinabung, which can include phreatic or magmatic eruptions,” he explained. He added that the potential for lava dome collapse could also occur if pressure within the magmatic system increases significantly. “The current activity level of Mount Sinabung is Level II (Alert) and has been since 17 May 2023,” he detailed. Since March 2024, the Centre for Volcanology and Geological Hazard Mitigation (PVMBG) has recommended that residents, tourists, and hikers refrain from activities within a 2-kilometre radius of the summit, and a 3.5-kilometre sectoral radius for the south-eastern sector of Mount Sinabung. In addition to the direct threat of incandescent rock ejections and ash dispersal, the public is also reminded of the potential for secondary hazards such as lahars, especially during the rainy season. Lahars could flow through rivers in the south-western sector that originate at the summit of Mount Sinabung.