September 2, 2026 | 09:09 pm
TEMPO.CO, Jakarta - On August 31, Mount Sinabung in Karo, North Sumatra, erupted after four years of inactivity. The eruption prompted authorities to raise the volcano's activity status by one level, from Alert Level II (Waspada) to Level III (Siaga).
However, Mount Sinabung was not the only volcano to erupt that day. The Center for Volcanology and Geological Hazard Mitigation (PVMBG) under the Geological Agency reported six volcanic eruptions occurring almost simultaneously on August 31.
The five other volcanoes were Mount Ibu in North Maluku, Mount Lewotobi Perempuan and Ili Lewotolok in East Nusa Tenggara, Mount Semeru in East Java, and Mount Anak Krakatau in the Sunda Strait.
Speaking at a press conference at the PVMBG office on Wednesday, September 2, 2026, PVMBG Head Siti Sumilah Rita Susilawati emphasized that researchers found no evidence of a single geological process triggering the six eruptions on the same day.
"Therefore, we ask the public not to assume Indonesia is undergoing a series of synchronized major eruptions," she said.
Rita added that the close timing of the eruptions does not mean the volcanoes are connected or triggering one another. Each volcano operates on its own magma system, distinct characteristics, and timeline of activity.
"Put simply, each volcano has its own 'kitchen,' and the processes leading to an eruption vary from one volcano to another," she explained.
Rita also addressed questions linking the eruptions to recent seismic activity, such as the magnitude 7.7 Flores earthquake on August 15. According to her, earthquakes and volcanic activity are separate geological phenomena.
While earthquakes can influence volcanic activity under specific conditions, she noted, "This only happens if the volcano is already active or nearing an eruption."
She cited the 2004 Aceh megathrust earthquake, which did not trigger eruptions in Aceh's volcanoes. "Therefore, an interconnected relationship cannot be concluded simply because two events occur close in time," she said.
Mount Sinabung's Alert Status
Rita detailed the situation at Mount Sinabung, where the August 31 eruption sent an ash column 3,500 meters into the sky.
Observation data from September 1, 2026, between 6:00 a.m. and 12:00 p.m. showed no further eruptions. However, white-to-grayish smoke continued to rise 100 to 300 meters above the peak. "Continuous volcanic seismicity and tremors are still being recorded, so we are monitoring the volcano closely," Rita said.
Based on the latest observation data, Mount Sinabung erupted again on Wednesday morning, September 2, 2026, at 7:20 a.m. WIB. The eruption produced a thick gray-to-brown ash column reaching 1,000 meters above the summit, drifting east and southeast.
Rita confirmed that the August 31 event was Sinabung's first eruption following a four-year lull. The Geological Agency currently maintains Mount Sinabung's activity status at Level III. "Volcanic activity increased throughout August, leading to the eruption at 10:17 a.m.," she noted.
Rita acknowledged that the alert status reflects heightened activity requiring greater caution, though it does not guarantee a larger eruption will follow. "Raising the status is a precautionary measure to ensure public safety," she said.
In defining danger zones, PVMBG considers specific eruption hazards. Authorities have prohibited activities within a 3-kilometer radius of the peak to protect against falling incandescent rock.
Meanwhile, a 6-kilometer exclusion zone has been established to the south and southeast to guard against potential lava flows and pyroclastic density currents (hot clouds). The boundary reflects historical eruption patterns where lava flows and hot clouds reached those distances.
"The south and southeast sectors require close monitoring, though danger zones may shift depending on the volcano's behavior," Rita added.
Read: Kualanamu Airport Reopens Following Mount Sinabung Eruption
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