Mount Mahameru Eruption in Indonesia Triggers Emergency Relocations

The nation's Semeru volcano, the tallest summit on the island of Java, has exploded, blanketing several villages with falling ash, leading to evacuations and leading authorities to raise the warning to the highest level.

The volcano in East Java province unleashed blistering plumes of fiery ash and a mixture of stone, molten rock, and gases that travelled up to 7km down its sides multiple times from noon to evening, while a dense plume of hot clouds rose 2km into the sky, as stated by Indonesia’s Geology Agency.

The outbursts that unfolded throughout the day forced officials to increase the volcano’s alert level twice, from the third-highest level to the highest, the authority said. No casualties have been reported.

Over three hundred residents in the three villages most at risk in the area of Lumajang region were evacuated to official safe havens, according to a representative for the national disaster mitigation agency.

He said that heightened volcanic movements of the mountain on the afternoon of Wednesday led authorities to expand the hazard area to 8km from the crater. People were advised to stay clear from an area along the Besuk Kobokan River, which is the path of the molten rock stream, as scorching gases moved down the volcano's sides.

Footage on online platforms showed a dense cloud of ash moving through a wooded ravine to a waterway beneath a bridge. Residents, some with faces covered with ash and water, escaped to temporary shelters or left for other safe areas.

Local media reported that authorities were facing challenges to save about 178 people stranded on the 12,060-foot peak at the Ranu Kumbolo monitoring post. The party included 137 hikers, 15 carriers, seven guides and six tourism officials, according to an spokesperson with the national park.

“They are currently safe at Ranu Kumbolo monitoring post,” a spokesperson said in a recorded message. He noted the station was located 4.5km from the summit on the north side of the volcano, which is outside the trajectory of the fiery cloud movement that was seen moving to the south-southeast. Inclement conditions and rain forced the group to spend the night there, he explained.

The volcano, also known as Mahameru, has erupted numerous times in the past 200 years. Still, as is the case with numerous of the 129 active volcanoes in Indonesia, thousands of people still to live on its fertile slopes.

The mountain's previous significant explosion was in late 2021, when 51 people were killed and several hundred others were burned and villages were buried in thick mud. The event forced the evacuation of more than 10,000 residents from their houses.

The country, an archipelago of more than 280 million people, sits along the Pacific “ring of fire”, a horseshoe-shaped series of tectonic boundaries, and is susceptible to seismic events and volcanism.