Mount Semeru Outburst in Indonesia Prompts Evacuations

Indonesia's Mount Semeru, the tallest summit on Java island, has exploded, covering multiple communities with falling ash, prompting evacuations and causing officials to elevate the warning to the maximum level.

The volcano in East Java province released blistering plumes of fiery ash and a mixture of rock, lava and gas that travelled up to 7km down its sides multiple times from noon to dusk, while a thick column of fiery clouds rose 2km into the sky, according to the nation's geological authority.

The outbursts that occurred throughout the day forced officials to increase the volcano’s alert level on two occasions, from the level three to the top level, the authority said. No deaths or injuries have been reported.

More than 300 inhabitants in the three villages most endangered in the district of Lumajang region were evacuated to official safe havens, as mentioned by a spokesperson for the national emergency management body.

He said that heightened volcanic movements of the volcano on Wednesday afternoon prompted authorities to expand the danger zone to 8km from the summit. People were urged to keep away 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 displayed a dense cloud of ash sweeping through a forested valley to a river beneath a overpass. Residents, some with faces covered with ash and rain, escaped to makeshift refuges or left for alternative secure locations.

Local media indicated that emergency teams were struggling to save about 178 people stranded on the 12,060-foot mountain at the Ranu Kumbolo monitoring post. The group comprised 137 hikers, 15 porters, seven escorts and six travel representatives, according to an official with the protected area.

“They remain secure at the Ranu Kumbolo station,” a spokesperson said in a video statement. He said the post was located 4.5km from the crater on the northern slope of the mountain, which is outside the trajectory of the hot cloud flow that was seen traveling to the southeast direction. Bad weather and rain forced the team to spend the night there, he explained.

Semeru, also called Mahameru, has erupted numerous times in the last two centuries. Still, as is the situation with many of the 129 active volcanoes in Indonesia, tens of thousands of people still to reside on its productive highlands.

Semeru’s previous significant explosion was in December 2021, when 51 people were killed and several hundred others were injured and settlements were submerged in layers of mud. The event led to the relocation of more than 10,000 residents from their houses.

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