Bukittinggi, West Sumatra. Authorities monitoring Mount Marapi, one of Indonesia’s most active volcanoes, have reported a string of equipment thefts that have compromised early warning systems on parts of the mountain.

Teguh Purnomo, head of the Mount Marapi observation post, said that since 2022, three sets of volcanic monitoring instruments have been stolen from stations located in Agam and Tanah Datar regencies in West Sumatra.

“These thefts have significantly disrupted monitoring operations, particularly on the eastern and southern flanks of the volcano,” Teguh said in Bukittinggi on Sunday.

The stolen components primarily include batteries used to power remote monitoring stations. Without these power sources, the stations are rendered inoperative, limiting coverage in key areas of the mountain.

Mount Marapi is under constant surveillance due to its status as one of Indonesia’s most active volcanoes. The December 3, 2023, eruption killed at least 24 hikers and injured dozens more. Another eruption in April last year caused at least 37 deaths.

Despite the setbacks, the Marapi Volcano Observation Center (PGA Marapi) still operates nine active monitoring stations around the mountain. According to Teguh, the existing stations -- strategically positioned around all cardinal directions -- are sufficient for comprehensive volcanic activity tracking.

“These nine monitoring points form an ideal network to observe Mount Marapi from all angles,” he explained.

Each station is equipped with vital instruments, including Seismographs, which detect tremors linked to earthquakes or underground magma movement, and Tiltmeters, which measure ground deformation, such as inflation caused by rising magma or deflation indicating magma withdrawal.

These instruments are essential for analyzing the condition of Marapi’s active crater -- particularly the Verbeek Crater, identified as the main source of recent volcanic activity.

Teguh said reliable, multi-directional monitoring and adequate sensor coverage are critical for accurately detecting signs of potential eruptions and issuing timely warnings to protect nearby communities.