Volcanic activity at Indonesian Mount Soputan is rapidly increasing with a new series of moderate to strong eruptions. On January 4, authorities raised the volcanic alert level from 2 to 3 (out of 4) and prohibited all activities within a radius of 4 km (2.5 miles) from the volcano. According to the Darwin VAAC, the volcanic ash reached an altitude of 12.8 km (42 000 feet) on January 5, 2016.

At 13:53 UTC (20:53 local time) on Monday, January 4, the volcano sent ash 2 km (6 500 feet) into the sky, the country's National Disaster Mitigation Agency (BNPB) spokesperson Sutopo Purwo Nugroho said.

Soputan eruption late January 4, 2016 (local time). Image credit: PVMBG

"The lava was seen decreasing in the east side of the volcano slope with thundering sounds heard from the crater of the volcano," Sutopo said and added that mild volcanic ash was observed in Langowan, Minahasa. "People are yet to be told to evacuate. The settlements are still out of the prohibited radius range."

Soputan eruption on January 4, 2016. Image credit: Himawari-8/JMA (SSEC) (via Culture Volcan)

At 23:38 UTC on January 4 (06:38 local time on January 5), PVMBG estimated the eruption column was reaching a height of approximately 6.5 km (21 300 feet) and was heading northwest. This is about 8.3 km (27 200 feet) above the sea level.

Soputan eruption during the morning hours of January 5, 2016 (local time). Image credit: PVMBG

Soputan eruption during the morning hours of January 6, 2015 (local time). Image credit: Fahrur Rozi (via @LeopoldAdam)

In their Volcanic Ash Advisory issued 11:00 UTC on January 5, the Darwin VAAC said the volcanic ash at 08:10 UTC today was observed reaching 3.6 km (12 000 feet), and was extending 102 km (63 miles) to the east. Volcanic ash to 12.8 km (42 000 feet) is expected to dissipate within the next 6 hours.

Geologic summary

The small Soputan stratovolcano on the southern rim of the Quaternary Tondano caldera on the northern arm of Sulawesi Island is one of Sulawesi's most active volcanoes. The youthful, largely unvegetated volcano rises to 1784 m and is located SW of Sempu volcano.

It was constructed at the southern end of a SSW-NNE trending line of vents. During historical time the locus of eruptions has included both the summit crater and Aeseput, a prominent NE-flank vent that formed in 1906 and was the source of intermittent major lava flows until 1924. (GVP)

Featured image: Mount Soputan eruption on January 4, 2016 (early morning hours of January 5, local time). Credit: PVMBG.