Volcano Semeru Outburst in Indonesia Prompts Emergency Relocations

Indonesia's Semeru volcano, the tallest summit on the island of Java, has exploded, covering several villages with volcanic ash, leading to evacuations and leading authorities to raise the alert to the highest 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 4 miles down its sides multiple times from noon to dusk, while a thick column of fiery clouds rose 1.2 miles into the air, as stated by Indonesia’s Geology Agency.

The outbursts that occurred throughout the day forced officials to raise the mountain's warning status on two occasions, from the third-highest level to the top level, the agency reported. No casualties have been announced.

Over three hundred inhabitants in the three communities most at risk in the area of Lumajang region were relocated to official safe havens, according to a representative for the national disaster mitigation agency.

He said that increased activity of the volcano on the afternoon of Wednesday prompted authorities to widen the danger zone to 8km from the crater. People were advised to keep away from an zone along the Kobokan River, which is the route of the lava flow, as searing gas moved down the volcano's sides.

Videos on social media displayed a thick plume of volcanic dust moving through a forested valley to a waterway beneath a bridge. Residents, some with faces smeared with volcanic dust and water, fled to makeshift refuges or departed for other safe areas.

Local media reported that emergency teams were facing challenges to save about 178 people trapped on the 3,676-metre peak at the Ranu Kumbolo monitoring post. The group included 137 hikers, 15 porters, seven guides and six travel representatives, according to an official with the national park.

“They are currently safe at Ranu Kumbolo monitoring post,” a spokesperson stated in a video statement. He noted the post was located 2.8 miles from the summit on the north side of the mountain, which is not in the path of the hot cloud flow that was observed moving to the south-southeast. Inclement conditions and precipitation forced the group to spend the night there, he added.

The volcano, also called Great Mountain, has burst many occasions in the past 200 years. Still, as is the situation with many of the 129 active volcanoes in the archipelago, tens of thousands of people still to live on its fertile slopes.

Semeru’s last major eruption was in late 2021, when 51 individuals were lost their lives and hundreds more were injured and settlements were buried in thick mud. The eruption led to the evacuation of more than 10,000 residents from their houses.

Indonesia, an archipelago of over 280 million people, sits along the Pacific seismic belt, a horseshoe-shaped series of fault lines, and is susceptible to seismic events and volcanism.