TEMPO.CO, Jakarta - Indonesia is experiencing heightened volcanic activity in several parts of the country, with five volcanoes erupting or showing significant activity over the past several days. Mount Anak Krakatau, Mount Ibu, Mount Sinabung, Mount Semeru, and Mount Lewotobi Laki-Laki are being closely monitored, with authorities urging residents and visitors to stay away from designated danger zones.
The latest reports from Bisnis Indonesia show that the volcanoes differ in activity levels and hazards, ranging from ash emissions and eruptions to potential pyroclastic flows and lava avalanches.
5 Indonesian Volcanoes Showing Volcanic Activity
1. Mount Anak Krakatau
Mount Anak Krakatau in the Sunda Strait erupted on the night of Friday, September 4, 2026, with continuous eruptions continuing until early Sunday, September 6.
According to the Center for Volcanology and Geological Hazard Mitigation (PVMBG), a single Strombolian-type eruption occurred at 3:53 a.m. local time on September 6 and lasted about 30 seconds. The eruption was tentatively interpreted as the conclusion of the preceding continuous eruption episode.
During observations from September 5 to 6, visibility around the volcano was generally clear but was occasionally obscured by fog. CCTV footage showed a red-hued eruption column at night and blackish plumes during the day.
Instrumental monitoring showed that the average Real-time Seismic Amplitude Measurement (RSAM) briefly increased on September 5 before declining the following day. Meanwhile, tiltmeter data from Tanjung Station continued to show an inflationary trend that had been observed since early August, while data from Lava93 Station remained relatively stable.
PVMBG has maintained Mount Anak Krakatau at Level III (Alert).
The public, tourists, and hikers are advised not to conduct activities within a three-kilometer radius of the volcano's center of activity.
2. Mount Ibu
Mount Ibu in North Maluku erupted on Sunday, September 6, at 10:04 a.m. local time, producing an ash column about 600 meters above the summit, or approximately 1,925 meters above sea level.
The ash column was white to gray with moderate to thick intensity and drifted northward. PVMBG recorded the eruption on a seismogram with a maximum amplitude of 28 millimeters and an initial duration of about 44 seconds.
Unlike the other volcanoes listed in the report, Mount Ibu is currently at Level II (Advisory) rather than Level III.
PVMBG advises residents and visitors to avoid activities within a two-kilometer radius of the crater, as well as within a 3.5-kilometer sectoral extension toward the crater opening on the northern side.
People outdoors are advised to wear masks and eye protection if ashfall occurs. Authorities have also urged residents to remain calm, avoid unverified information and follow instructions from local governments.
3. Mount Sinabung
Mount Sinabung in Karo Regency, North Sumatra, was raised to Level III (Alert) on Sunday, September 6, at noon.
PVMBG monitoring has recorded thick white crater smoke rising 300 to 500 meters above the summit. However, drone observations found no signs of new lava dome growth at the volcano's eruption center.
No rockfall earthquakes associated with instability in the old lava dome have been detected, suggesting that the existing dome remains stable. PVMBG said earthquakes associated with magma supply and increased pressure at shallow depths were still being recorded, although their numbers were not significant.
Under the latest recommendations, the exclusion zone remains three kilometers from the summit, while the sectoral radius in the southeast has been reduced from six kilometers to five kilometers.
PVMBG advises the public, tourists, and hikers to avoid activities within three kilometers of the summit and within the five-kilometer sectoral zone to the southeast.
4. Mount Semeru
Mount Semeru, on the border of Lumajang and Malang regencies in East Java, erupted on Sunday morning, September 6, sending an ash column about 1,000 meters above the Mahameru summit.
The eruption occurred at 7:15 a.m. local time, according to Sigit Rian Alfian, an officer at the Mount Semeru Observation Post, as reported by Antara.
The ash column was white to gray with thick intensity and drifted eastward. The eruption was recorded on a seismograph with a maximum amplitude of 23 millimeters and lasted 102 seconds.
Mount Semeru remains at Level III (Alert).
Authorities have prohibited outdoor activities, particularly in the southeastern sector along the Besuk Kobokan drainage, extending 13 kilometers from the summit.
People are also prohibited from conducting activities within 500 meters of the riverbanks along Besuk Kobokan because pyroclastic flows and lahars could potentially travel up to 17 kilometers from the summit.
In addition, activities within a five-kilometer radius of the crater or summit are prohibited because of the risk of ejected incandescent rocks.
Authorities have urged residents to remain vigilant for pyroclastic flows, lava avalanches, and lahars along rivers and valleys originating from the summit.
5. Mount Lewotobi Laki-Laki
Mount Lewotobi Laki-Laki in Wulanggitang District, East Flores, East Nusa Tenggara, remains at Level III (Alert).
PVMBG reported on Sunday, September 6, that white smoke with thin to moderate intensity was rising about 50 to 100 meters above the summit. Visibility at the volcano was generally clear to cloudy, with light winds blowing toward the west and northwest.
The volcano most recently erupted on September 1 at 12:42 p.m. local time, producing a gray ash column about 300 meters above the summit, or approximately 1,884 meters above sea level.
The eruption was recorded on a seismograph with a maximum amplitude of 29.6 millimeters and lasted about three minutes and 17 seconds. The ash drifted west and northwest.
PVMBG advises the public and tourists to avoid activities within a five-kilometer radius of the eruption center.
Residents are also urged to remain alert for rain-triggered lava floods in rivers originating from the summit, particularly during periods of heavy rainfall.
Authorities have specifically warned communities in areas including Dulipali, Padang Pasir, Nobo, Nurabelen, Klatanlo, Hokeng Jaya, Boru, and Nawakote.
The PVMBG has urged the public to remain calm, follow local government directives, and rely on verified information about volcanic activity.
Read: 6 Indonesian Airports Remain Closed as Anak Krakatau Ash Disrupts Flights
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