Mount Mahameru Outburst in Indonesia Prompts Emergency Relocations

Indonesia's Semeru volcano, the tallest summit on the island of Java, has exploded, blanketing multiple communities with volcanic ash, leading to evacuations and leading authorities to raise the alert to the highest level.

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

The outbursts that occurred throughout the day compelled officials to increase the volcano’s alert level twice, from the level three to the top level, the authority said. No casualties have been announced.

More than 300 inhabitants in the three villages most endangered in the area of Lumajang region were evacuated to government shelters, as mentioned by a representative for the national emergency management body.

He stated that heightened volcanic movements of the volcano on Wednesday afternoon prompted authorities to expand the hazard area to 8km from the summit. Residents were urged to stay clear from an area along the Kobokan River, which is the route of the lava flow, as searing gas flowed down the volcano's sides.

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

Local media reported that authorities were struggling to save about 178 people trapped on the 3,676-metre peak at the Ranu Kumbolo observation station. The group comprised 137 climbers, 15 porters, seven guides and six tourism officials, according to an official with the protected area.

“They remain secure at the Ranu Kumbolo station,” a spokesperson said in a recorded message. He noted the station was situated 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 traveling to the southeast direction. Inclement conditions and rain forced the group to spend the night there, he added.

Semeru, also called Great Mountain, has erupted many occasions in the last two centuries. However, as is the situation with many of the 129 active volcanoes in Indonesia, tens of thousands of residents continue to live on its productive highlands.

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

Indonesia, an island chain of over 280 million people, is located along the Pacific seismic belt, a curved series of tectonic boundaries, and is susceptible to earthquakes and volcanism.