Mount Mahameru Outburst in Indonesia Triggers Evacuations

The nation's Mount Semeru, the tallest summit on the island of Java, has erupted, covering multiple communities with volcanic ash, leading to evacuations and causing officials to elevate the alert to the maximum level.

The volcano in the province of East Java unleashed blistering plumes of fiery ash and a mixture of rock, lava and gas that travelled up to 7km down its slopes several times from noon to dusk, while a thick column of hot clouds rose 1.2 miles into the sky, as stated by the nation's geological authority.

The eruptions that occurred throughout the day compelled officials to raise the volcano’s alert level twice, from the level three to the highest, the authority reported. No casualties have been announced.

Over three hundred residents in the three communities most at risk in the area of Lumajang region were relocated to official safe havens, as mentioned by a spokesperson for the national disaster mitigation agency.

He said that increased activity of the mountain on Wednesday afternoon prompted authorities 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 route of the molten rock stream, as searing gas moved down the volcano's sides.

Footage on social media displayed a thick plume of volcanic dust moving through a wooded ravine to a river beneath a bridge. Residents, some with faces smeared with volcanic dust and water, fled to makeshift refuges or departed for alternative secure locations.

Regional news outlets indicated that authorities were facing challenges to rescue about 178 individuals trapped on the 3,676-metre peak at the Ranu Kumbolo monitoring post. The group comprised 137 hikers, 15 carriers, seven guides and six tourism officials, according to an official with the national park.

“They are currently safe at the Ranu Kumbolo station,” a spokesperson stated in a recorded message. He noted the station was situated 2.8 miles from the crater on the north side of the mountain, which is outside the trajectory of the hot cloud flow that was observed traveling to the south-southeast. Inclement conditions and precipitation forced the team to remain overnight there, he explained.

The volcano, also known as Great Mountain, has erupted many occasions in the last two centuries. Still, as is the case with many of the 129 active volcanoes in Indonesia, tens of thousands of residents still to reside on its fertile slopes.

The mountain's previous significant explosion was in December 2021, when 51 individuals were lost their lives and several hundred more were injured and settlements were submerged in layers of mud. The eruption led to the evacuation of more than 10,000 people from their homes.

The country, an archipelago of over 280 million people, is located along the Pacific “ring of fire”, a horseshoe-shaped series of tectonic boundaries, and is susceptible to earthquakes and volcanism.