Mount Mahameru Eruption in Indonesia Triggers Evacuations

The nation's Mount Semeru, the highest peak on the island of Java, has exploded, covering several villages with falling ash, prompting evacuations and leading authorities to raise the alert to the maximum level.

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

The eruptions that unfolded throughout the day compelled authorities to raise the volcano’s alert level on two occasions, from the level three to the top level, the agency reported. No casualties have been reported.

More than 300 inhabitants in the three communities most endangered in the area of Lumajang were evacuated to official safe havens, as mentioned by a representative for the national disaster mitigation agency.

He said that increased activity of the volcano on the afternoon of Wednesday led authorities to widen the danger zone to 8km from the summit. People were advised to keep away from an area 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 online platforms displayed a dense cloud of volcanic dust sweeping through a wooded ravine to a river beneath a bridge. Residents, some with faces covered with ash and water, fled to temporary shelters or left for alternative secure locations.

Regional news outlets reported that emergency teams were struggling to rescue about 178 individuals trapped on the 3,676-metre peak at the Ranu Kumbolo monitoring post. The group comprised 137 climbers, 15 carriers, seven escorts and six travel representatives, according to an spokesperson with the protected area.

“They remain secure at the Ranu Kumbolo station,” an official said in a video statement. He noted the post was located 2.8 miles from the crater on the northern slope of the mountain, which is not in the path of the hot cloud flow that was seen moving to the south-southeast. Bad weather and precipitation required the group to remain overnight there, he explained.

The volcano, also known as Great Mountain, has erupted numerous times in the past 200 years. However, as is the case with many of the 129 active volcanoes in Indonesia, tens of thousands of people still to reside on its fertile slopes.

Semeru’s last major eruption was in December 2021, when 51 people were killed and hundreds others were burned and settlements were buried in thick mud. The event forced the relocation of over ten thousand residents from their homes.

The country, an island chain of over 280 million inhabitants, sits along the Pacific seismic belt, a curved series of fault lines, and is susceptible to seismic events and volcanic activity.