Mount Merapi

Mount Merapi, whose name combines the Sanskrit *Meru* (“mountain”) with the Javanese *api* (“fire”), sits on the border between Central Java and the Special Region of Yogyakarta in Indonesia. This active stratovolcano has been erupting regularly since 1548, making it the most active volcano in the country. It lies about 28 kilometers north of Yogyakarta city, home to 2.4 million people, and thousands of residents live on its slopes, with villages perched as high as 1,700 meters above sea level.

Smoke frequently rises from the summit, and past eruptions have been deadly. On 22 November 1994, a pyroclastic flow from a large explosion killed 27 people, mostly in the village of Turgo on the southern slope. Another major eruption occurred in 2006, just after the Yogyakarta earthquake. Because of the hazards Merapi poses to densely populated areas, it was named one of the Decade Volcanoes—volcanoes singled out for close study due to their history of large, destructive eruptions and proximity to people.

On the afternoon of 25 October 2010, Merapi erupted on its southern and southwestern slopes. Over the next month, 353 people died, and 350,000 were forced to evacuate. Most damage came from pyroclastic flows, and heavy rain on 4 November triggered lahars that caused further destruction. Most fissures stopped erupting by 30 November, and the official threat level was lowered four days later. The eruption changed Merapi’s shape, lowering its height to a commonly cited 2,968 m (9,738 ft).

Since 2010, smaller eruptions have occurred, including two phreatic events on 18 November 2013 and 11 May 2018. The first, larger one—caused by rainfall and internal activity—sent smoke up to 2,000 meters. Several small eruptions have taken place since early 2020, drawing continued interest from volcanologists.

Geologically, Merapi is the youngest volcano in a group in southern Java, sitting above a subduction zone where the Indo-Australian plate slides under the Sunda plate. It is one of at least 129 active volcanoes in Indonesia, part of the Pacific Ring of Fire. Stratigraphic analysis shows eruptions began about 400,000 years ago, with effusive, basaltic lava flows until roughly 10,000 years ago. Since then, eruptions have become more explosive, producing viscous andesitic lavas that often form lava domes. Dome collapses generate pyroclastic flows, and larger explosions create