Jakarta [Indonesia], August 12 (ANI): An earthquake measuring 6.3 on the Richter scale struck Indonesia on Tuesday, the National Center for Seismology (NCS) reported. The quake occurred at a depth of 39 kilometers.
In a post on X, the NCS stated: “EQ of M: 6.3, On: 12/08/2025 13:54:27 IST, Lat: 2.09 S, Long: 138.81 E, Depth: 39 Km, Location: West Papua, Indonesia.”
Earlier, on August 7, another earthquake with a magnitude of 4.9 struck at a depth of 106 kilometers. The NCS reported: “EQ of M: 4.9, On: 07/08/2025 20:59:00 IST, Lat: 1.03 N, Long: 98.80 E, Depth: 106 Km, Location: Northern Sumatra, Indonesia.”
Indonesia lies between two major tectonic plates—the Australian Plate and the newly separated Sunda Plate—making its tectonic setting highly complex. The country sits between two continental plates, the Sahul Shelf and the Sunda Plate, and two oceanic plates, the Pacific Plate and the Philippine Sea Plate.
The subduction of the Indian Plate beneath the Sunda Plate formed the volcanic arc in western Indonesia, one of the most seismically active regions in the world. This area has a long history of powerful eruptions and earthquakes. The chain of active volcanoes created Sumatra, Java, Bali, and the Lesser Sunda Islands, most of which, particularly Java and Bali, emerged within the last two to three million years.
In eastern Indonesia, tectonics are driven by the movements of the Pacific and Sahul plates. Subduction occurs along southeastern Sumatra and western Java. While Sumatra has been more active in recent years despite sharing the same subduction margin as West Java, this difference is likely due to the time frame rather than a lack of tectonic activity. Large-scale earthquakes may occur off Sumatra every 100 years, while they may take roughly 500 years to occur off the coast of western Java.
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