Mount Mahameru Outburst in Indonesia Triggers Evacuations

The nation's Semeru volcano, the tallest summit on Java island, has erupted, blanketing several villages with falling ash, prompting evacuations and leading authorities to raise the alert to the maximum level.

The volcano in East Java province released searing clouds of hot ash and a combination of rock, lava and gas that moved up to 7km down its slopes multiple times from noon to evening, while a dense plume of fiery clouds rose 2km into the air, as stated by Indonesia’s Geology Agency.

The outbursts that occurred throughout the day compelled officials to increase the mountain's warning status twice, from the third-highest level to the highest, the agency said. No casualties have been reported.

More than 300 residents in the three communities most at risk in the area of Lumajang were evacuated to government shelters, as mentioned by a representative for the national disaster mitigation agency.

He stated that heightened volcanic movements of the volcano on the afternoon of Wednesday led authorities to widen the hazard area to 8km from the summit. People were urged to stay clear from an zone along the Kobokan River, which is the path of the molten rock stream, as searing gas moved down the volcano's sides.

Footage on social media showed a dense cloud of ash moving through a forested valley to a river beneath a bridge. Locals, some with faces covered with volcanic dust and rain, escaped to makeshift refuges or left for other safe areas.

Local media indicated that emergency teams were facing challenges to save about 178 people stranded on the 3,676-metre mountain at the Ranu Kumbolo observation station. The group included 137 hikers, 15 carriers, seven escorts and six tourism officials, according to an official with the national park.

“They remain secure at Ranu Kumbolo monitoring post,” an official said in a recorded message. He noted the station was located 4.5km from the summit on the northern slope of the mountain, which is not in the path of the hot cloud flow that was observed moving to the south-southeast. Bad weather and precipitation forced the team to spend the night there, he added.

The volcano, also known as Great Mountain, has erupted many occasions in the last two centuries. However, as is the case with numerous of the 129 active volcanoes in Indonesia, thousands of people continue to live on its productive highlands.

The mountain's last major eruption was in December 2021, when 51 individuals were killed and hundreds more were injured and villages were submerged in layers of mud. The event forced the relocation of over ten thousand residents from their homes.

Indonesia, an archipelago of over 280 million people, is located along the Pacific “ring of fire”, a curved series of tectonic boundaries, and is prone to earthquakes and volcanic activity.