Mount Sinabung erupts again, these are the areas to watch
Mount Sinabung in Karo Regency, North Sumatra, erupted again on Monday (31/8). The volcanic ash column was observed reaching approximately 3,500 metres above the summit, and the volcano’s activity level was subsequently raised to Level III, or Standby.
The eruption occurred at around 10.17 Western Indonesia Time. According to a report from the Geological Agency of the Ministry of Energy and Mineral Resources (ESDM), the thick black ash column moved towards the east and southeast. Its height reached approximately 5,960 metres above sea level.
The Geological Agency recorded the eruption on a seismogram with a maximum amplitude of 120 millimetres. Increased volcanic activity was also evident from the seismicity that occurred before the eruption.
On 31 August 2026, 85 volcanic earthquakes, one blast earthquake and one harmonic tremor were recorded. These data served as one of the bases for raising the activity status of Mount Sinabung.
Mount Sinabung had previously been at Level II, or Alert, since 17 May 2023. Following the eruption and increased volcanic activity, the Geological Agency raised its status to Level III, or Standby, effective from 12.30 Western Indonesia Time on 31 August 2026.
A volcanic eruption occurs as a result of volcanic processes within the body of the mountain, when pressure and the movement of magma and volcanic gases push material out through the crater conduit.
In the case of the Sinabung eruption on 31 August 2026, the Geological Agency stated that the event was an initial eruption. Therefore, the possibility of larger activity or eruptions remains.
Head of the Geological Agency Lana Saria said that developments in Mount Sinabung’s activity would continue to be monitored and that the activity level could be evaluated at any time should significant changes occur.
As the status of Mount Sinabung was raised to Level III, or Standby, the Geological Agency established a number of activity restrictions that the public must observe.
Residents, visitors and tourists are asked not to carry out activities in villages that have been relocated.
In addition, the public is prohibited from carrying out activities within a 3-kilometre radius of the summit of Mount Sinabung, as well as within a 6-kilometre sectoral radius towards the south-southeast.
Areas around rivers whose headwaters are on Mount Sinabung also need to increase vigilance against the possibility of lahars, especially if high-intensity rainfall occurs.
The Geological Agency asked the public to remain calm, but to increase vigilance regarding developments in the volcano’s activity.
Residents of Karo Regency are also asked to follow the instructions of the North Sumatra Regional Disaster Management Agency (BPBD) and the Karo Regency BPBD, and not to believe information about the eruption that cannot be accounted for.
Developments in Mount Sinabung’s activity can be monitored through the MAGMA Indonesia application as well as the official channels of the Centre for Volcanology and Geological Hazard Mitigation (PVMBG) and the Geological Agency.
With the status now raised to Standby, residents around Mount Sinabung need to comply with the danger zones and avoid activities in the designated areas. The government and monitoring officers are also continuing to evaluate developments in the volcano’s activity.