Mount Semeru Outburst in Indonesia Triggers Emergency Relocations

The nation's Semeru volcano, the tallest summit on Java island, has exploded, covering multiple communities with falling ash, prompting evacuations and leading authorities to raise the warning to the maximum level.

The volcano in the province of East Java unleashed searing clouds of fiery ash and a combination of rock, lava and gas that travelled up to 7km down its sides several times from noon to evening, while a dense plume of hot clouds rose 2km into the air, according to Indonesia’s Geology Agency.

The outbursts that occurred throughout the day forced authorities to raise the mountain's warning status on two occasions, from the third-highest level to the highest, the agency reported. No casualties have been announced.

More than 300 residents in the three villages most at risk in the area of Lumajang region were evacuated to government shelters, according to a representative for the national emergency management body.

He said that heightened volcanic movements of the volcano on Wednesday afternoon prompted officials to expand the danger zone to 8km from the crater. Residents were urged to stay clear from an zone along the Besuk Kobokan River, which is the path of the lava flow, as searing gas flowed down the volcano's sides.

Videos on social media displayed a thick plume of volcanic dust moving through a wooded ravine to a waterway beneath a bridge. Residents, some with faces smeared with volcanic dust and rain, fled to temporary shelters or left for other safe areas.

Local media reported that emergency teams were facing challenges to save about 178 individuals trapped on the 3,676-metre mountain at the Ranu Kumbolo observation station. The group comprised 137 climbers, 15 porters, seven escorts and six travel representatives, according to an official with the national park.

“They are currently safe at Ranu Kumbolo monitoring post,” a spokesperson said in a video statement. He said the post was located 2.8 miles from the crater on the north side of the volcano, which is not in the path of the fiery cloud movement that was seen moving to the south-southeast. Bad weather and rain required the team to remain overnight there, he explained.

Semeru, also called Mahameru, has burst many occasions in the last two centuries. Still, as is the situation with many of the 129 active volcanoes in the archipelago, tens of thousands of residents still to reside on its fertile slopes.

Semeru’s previous significant explosion was in late 2021, when 51 people were killed and hundreds more were injured and settlements were submerged in layers of mud. The event forced the evacuation of over ten thousand people from their houses.

Indonesia, an archipelago of over 280 million people, is located along the Pacific seismic belt, a horseshoe-shaped series of fault lines, and is susceptible to earthquakes and volcanism.