Mount Semeru Outburst in Indonesia Triggers Evacuations

Indonesia's Mount Semeru, the highest peak on the island of Java, has erupted, blanketing multiple communities with falling ash, leading to evacuations and causing officials to elevate the warning to the maximum level.

The mountain in the province of East Java unleashed blistering plumes of hot ash and a combination of stone, molten rock, and gases that travelled up to 4 miles down its slopes several times from midday to dusk, while a thick column of fiery clouds rose 2km into the sky, according to Indonesia’s Geology Agency.

The outbursts that occurred throughout the day forced authorities to raise the volcano’s alert level twice, from the third-highest level to the highest, the agency reported. No casualties have been announced.

More than 300 residents in the three communities most endangered in the area of Lumajang were relocated to government shelters, as mentioned by a representative for the national emergency management body.

He stated that increased activity of the volcano on the afternoon of Wednesday led officials to expand the hazard area to 5 miles from the summit. People were advised to stay clear from an zone along the Besuk Kobokan River, which is the path of the lava flow, as scorching gases moved down Semeru’s slopes.

Videos on online platforms showed a dense cloud of ash moving through a wooded ravine to a river beneath a bridge. Locals, some with faces covered with volcanic dust and rain, fled to makeshift refuges or left for other safe areas.

Local media reported that authorities were facing challenges to save about 178 people stranded on the 3,676-metre peak at the Ranu Kumbolo monitoring post. The party included 137 hikers, 15 carriers, seven escorts and six tourism officials, according to an official with the protected area.

“They remain secure at Ranu Kumbolo monitoring post,” a spokesperson stated in a video statement. He said the post was located 4.5km from the crater on the north side of the mountain, which is not in the path of the hot cloud flow that was observed moving to the southeast direction. Inclement conditions and precipitation required the team to remain overnight there, he added.

Semeru, also known as Great Mountain, has erupted numerous times in the past 200 years. However, as is the case with many of the 129 live volcanoes in Indonesia, thousands of residents continue to live on its fertile slopes.

The mountain's last major eruption was in December 2021, when 51 individuals were lost their lives and several hundred others were burned and settlements were buried in thick mud. The event forced the relocation of more than 10,000 residents from their homes.

The country, an archipelago of over 280 million inhabitants, is located along the Pacific seismic belt, a horseshoe-shaped series of tectonic boundaries, and is susceptible to seismic events and volcanism.