Mount Merapi
Indonesia's most persistently active volcano, looming over the city of Yogyakarta in central Java
Merapi's name means Mountain of Fire, and it has earned it. The steep cone in central Java, about 30 kilometers north of the city of Yogyakarta, has erupted dozens of times in recorded history and has been in a near-continuous eruptive phase since late 2020, slowly pushing out lava domes that crumble into glowing avalanches and pyroclastic flows. Hundreds of thousands of people farm the fertile soils on its flanks, which makes it one of the most closely watched volcanoes in the world. Its 2010 eruption, the largest there in more than a century, killed about 350 people, and the mountain holds a central place in Javanese tradition as a sacred site tied to the sultans of Yogyakarta.
Merapi is a stratovolcano rising to about 2,910 meters, though its summit height changes as lava domes grow and collapse. It is the youngest and most active of a group of volcanoes in central Java formed where the Indo-Australian Plate sinks beneath the Sunda Plate. Its typical activity is the slow growth of a viscous lava dome at the summit, which periodically collapses down the flanks in pyroclastic flows, locally called wedhus gembel, or shaggy goats, for their billowing look. Heavy rain then turns loose debris into lahars that sweep down river valleys such as the Gendol, Boyong and Krasak. Since 2021 two domes have grown, one in the summit crater and one on the upper southwest flank, sending lava avalanches up to about 2 kilometers downslope and occasional longer pyroclastic flows.
A large eruption in 1930 killed about 1,300 people, and in 1994 a pyroclastic flow killed more than 60. The 2010 eruption, rated VEI 4, sent flows about 15 kilometers down the Gendol valley and displaced some 350,000 people, and among the dead was the mountain's traditional spiritual guardian, who had declined to leave his village. Indonesia's Center for Volcanology and Geological Hazard Mitigation, through its Yogyakarta office (BPPTKG), raised Merapi to Level III, Siaga or alert, on a four-step scale in November 2020, and it remained there in October 2026. Authorities keep people out of zones reaching 3 to 7 kilometers from the summit, depending on the sector. The Global Volcanism Program reported continuing dome growth and frequent lava avalanches through mid-October 2026.