Volcano Semeru Outburst in Indonesia Prompts Emergency Relocations

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

The mountain 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 midday to dusk, while a thick column of hot 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 mountain's warning status twice, from the third-highest level to the highest, the agency reported. No deaths or injuries have been announced.

More than 300 residents in the three communities most at risk in the district of Lumajang were relocated to official safe havens, as mentioned by a spokesperson for the national disaster mitigation agency.

He said that increased activity of the volcano on the afternoon of Wednesday prompted officials to widen the hazard area to 5 miles from the crater. People were advised to stay clear from an area along the Besuk Kobokan River, which is the route of the molten rock stream, as searing gas flowed down Semeru’s slopes.

Videos on social media showed a dense cloud of volcanic dust sweeping through a wooded ravine to a river beneath a overpass. Locals, some with faces smeared with ash and water, fled to temporary shelters or left for alternative secure locations.

Local media reported that authorities were struggling to rescue about 178 individuals trapped on the 3,676-metre mountain at the Ranu Kumbolo monitoring post. The group included 137 climbers, 15 carriers, seven guides and six travel representatives, according to an spokesperson with the national park.

“They remain secure at Ranu Kumbolo monitoring post,” an official said in a video statement. He said the post was located 2.8 miles from the crater on the northern slope of the volcano, which is not in the path of the fiery cloud movement that was observed moving to the southeast direction. Inclement conditions and rain required the team to spend the night there, he explained.

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

Semeru’s previous significant explosion was in December 2021, when 51 individuals were killed and hundreds more were injured and settlements were buried in thick mud. The event led to the relocation of more than 10,000 people from their homes.

Indonesia, an island chain of over 280 million inhabitants, is located along the Pacific “ring of fire”, a horseshoe-shaped series of tectonic boundaries, and is susceptible to earthquakes and volcanism.