Mount Merapi erupts, pyroclastic flow reaches 2 km toward Boyong River

Mount Merapi, located on the border between Central Java and Yogyakarta Special Region, increased its volcanic activity on Saturday, 26 September 2026. The Geological Agency (Badan Geologi) under the Ministry of Energy and Mineral Resources reported a pyroclastic flow event at 20:34 local time (WIB), with material traveling an estimated 2 kilometers south toward the Boyong River channel in Sleman Regency, Yogyakarta.

Seismic monitoring by the Geological Disaster Research and Development Center (BPPTKG) recorded a maximum amplitude of 48.66 millimeters with an earthquake duration of 129.64 seconds. The pyroclastic flow was directed toward the southern sector, specifically along the Boyong River, which originates from Mount Merapi.

In response to the elevated volcanic activity, BPPTKG raised the alert status to Level III (Alert). The Geological Agency advised the public to avoid all activities in hazard-prone areas, particularly riverbeds originating from Mount Merapi, to protect against threats from lava flows, pyroclastic material, and potential cold lava flows during heavy rainfall. Residents were instructed to remain calm and monitor official updates from BPPTKG and the Geological Agency through verified sources.

The eruption occurred on the same night as another volcanic event: Mount Marapi in Tanah Datar, West Sumatra, also erupted at approximately 21:40 WIB on 26 September. That eruption produced a seismic signal with a maximum amplitude of 30 millimeters lasting approximately 1 minute 19 seconds, though ash column height was not observed.