Sukarjito, Jakarta – Indonesia experienced a high level of seismic activity throughout 2025, with more than 43,000 earthquakes recorded across the archipelago, according to the Meteorology, Climatology, and Geophysics Agency (BMKG). Despite the high frequency of earthquakes, the human toll from seismic events remained relatively low.
BMKG data show that a total of 43,439 earthquakes occurred nationwide over the course of the year. The vast majority were low-magnitude events, underscoring Indonesia's position along some of the world's most active tectonic boundaries.
"Of the total, 43,286 earthquakes had magnitudes below 5.0, while 153 events were classified as moderate to strong, with magnitudes of 5.0 or higher," Daryono, director of earthquakes and tsunamis at BMKG, said Friday. He described the elevated activity as a reminder of the need to strengthen disaster mitigation and preparedness.
One of the deadliest earthquakes in 2025 was a magnitude-5.8 quake that struck Poso, Central Sulawesi, on Aug. 17, killing two people.
BMKG said that only 973 earthquakes throughout the year were felt by residents. Of those, 25 were classified as damaging, causing destruction to homes and public facilities. Many other earthquakes were either centered offshore or occurred at significant depths, limiting their surface impact.
Indonesia's high seismicity is driven by the interaction of four major tectonic plates, according to the Geological Agency under the Ministry of Energy and Mineral Resources. These earthquake sources are located both offshore and on land.
The country's main earthquake-generating zones are associated with subduction processes, where oceanic plates descend beneath continental plates. These subduction zones stretch from western Sumatra, along the southern coast of Java and Nusa Tenggara, before curving toward the Maluku Islands. Similar tectonic processes are also found north of Sulawesi and Papua.
In eastern North Sulawesi to the western part of Halmahera Island, the Geological Agency identifies a rare double subduction system, known as "double subduction," where two plates sink beneath one another.
Subduction zones in Indonesia are further classified by depth. Shallow subduction areas at depths of less than 40 kilometers are known as megathrust zones, which have the potential to generate large and destructive earthquakes and tsunamis. Deeper subduction zones, at depths greater than 40 kilometers, are referred to as intraslab zones.
As Indonesia enters 2026, BMKG said it is intensifying monitoring in regions where tectonic energy may be accumulating. Authorities urged communities living near active fault lines to remain vigilant and to consider not only earthquake magnitude but also potential ground-shaking and secondary hazards.
"High seismic activity should be treated as a warning to continuously improve preparedness," Daryono said, stressing that awareness and mitigation remain critical to reducing earthquake risks.