Mount Mahameru Outburst in Indonesia Triggers Evacuations

The nation's Semeru volcano, the tallest summit on the island of Java, has exploded, blanketing multiple communities with falling ash, leading to evacuations and causing officials to elevate the warning to the highest level.

The mountain in the province of East Java released blistering plumes of fiery ash and a mixture of rock, lava and gas that moved up to 4 miles down its sides several times from noon to evening, while a dense plume of fiery clouds rose 2km into the air, according to Indonesia’s Geology Agency.

The outbursts that occurred throughout the day forced officials to increase the volcano’s alert level on two occasions, from the third-highest level to the top level, the agency reported. No casualties have been announced.

More than 300 residents in the three communities most endangered in the district of Lumajang were relocated to official safe havens, as mentioned by a spokesperson for the national disaster mitigation agency.

He said that heightened volcanic movements of the volcano on the afternoon of Wednesday prompted authorities to widen the hazard area to 5 miles from the summit. People were urged to keep away from an zone along the Kobokan River, which is the path of the lava flow, as scorching gases moved down the volcano's sides.

Videos on online platforms showed a dense cloud of ash sweeping through a wooded ravine to a river beneath a bridge. Residents, some with faces covered with ash and rain, escaped to makeshift refuges or departed for other safe areas.

Regional news outlets indicated that emergency teams were facing challenges to save about 178 people trapped on the 3,676-metre mountain at the Ranu Kumbolo monitoring post. The group included 137 hikers, 15 carriers, seven escorts and six tourism officials, according to an spokesperson with the protected area.

“They are currently safe at Ranu Kumbolo monitoring post,” an official said in a recorded message. He said the station was situated 4.5km from the crater on the north side of the mountain, which is not in the path of the fiery cloud movement that was seen moving to the south-southeast. Inclement conditions and rain forced the team to remain overnight there, he added.

The volcano, also known as Mahameru, has burst many occasions in the last two centuries. However, as is the situation with many of the 129 live volcanoes in Indonesia, tens of thousands of people continue to live on its fertile slopes.

Semeru’s previous significant explosion was in late 2021, when 51 people were lost their lives and hundreds others were burned and settlements were buried in thick mud. The eruption forced the evacuation of over ten thousand people from their houses.

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