Meratus Fault Warning in Endonezya: Risk of Major Earthquake in Güney Kalimantan

The Güney Kalimantan region of Endonezya is under serious threat due to increased seismic activity in recent years. According to the records of the Balikpapan Jeofizik İstasyonu, while the number of earthquakes occurring in the region was 94 in 2023, this figure showed a striking increase, rising to 238 in 2024 and 240 in 2025. Authorities state that this situation is not a coincidence and is closely related to the active fault lines in the region. The Meratus Fayı, which is located in the region and is active, is among the most critical points closely monitored by scientists. Current data and geological studies clearly reveal that this fault line has the potential to cause much greater destruction in the future.

The Meratus Fayı, which stands out as the most critical geological structure in the region, has been identified as a thrust fault (kıvrım/itme fayı) approximately 110 kilometers in length. Scientists carried out detailed risk analyses of this line based on the 1994 Wells ve Coppersmith formulation. The findings obtained show that if all segments of the fault move simultaneously, it has the potential to produce a destructive earthquake reaching a magnitude of 7. Moreover, since this fault line passes directly through land, the effects of a possible major earthquake are expected to spread over a very wide area. How the soil and rock structures in the region will absorb or intensify these tremors will directly affect the extent of possible damage that may occur.

The risks in question are not theoretical; they have been proven repeatedly by the earthquakes that have hit the region in recent years. For example, on 13 Şubat 2024, an earthquake with a magnitude of 4,8 was recorded, with its epicenter 19 kilometers northeast of Banjarmasin. This tremor, which occurred at a depth of ten kilometers, was felt with an intensity of degree III according to the Değiştirilmiş Mercalli Yoğunluğu (MMI) scale in many settlements such as bançar, Tapin, Barito Kuala and Banjarmasin şehri. The impact of the tremor was so strong that it reached the cities of Doğu Kotawaringin, Pulang Pisau ve Palangkaraya in Orta Kalimantan, where an MMI intensity of II-III was measured. This event demonstrated how active the Meratus Fayı is and its capacity to affect large areas.

Another significant tremor that occurred in the region took place on 4 Aralık 2025 and was recorded 95 kilometers southwest of Tanah Laut ilçesinin. This 4,9 magnitude earthquake, which occurred at a very shallow depth of three kilometers, did not cause any major structural damage but was noticed by the masses. The tremor, which spread rapidly to the Banjarbaru bölgesine, was felt there with an intensity of II-III MMI and caused brief panic among the public. Such similar shallow earthquakes are considered concrete proof of how clearly crustal movements can be felt. Authorities consider the absence of damage a matter of chance, but they emphasize the need to be prepared for potentially higher-magnitude tremors in the future.

In light of all this data, Rasmid, Manager of the Balikpapan Jeofizik İstasyonu, stated that the Meratus Fayı is in constant and dynamic motion. Five different seismograph devices specially placed in the region to continuously monitor the fault line regularly record earthquake activities every month. Rasmid emphasizes that monitoring studies in this direction are of vital importance to minimize geological risks in the region and strengthen early warning systems. Local governments and the public are encouraged to strengthen the infrastructure of buildings and focus on disaster preparedness training against a possible magnitude 7 scenario. Currently, this seismic threat in Güney Kalimantan makes it mandatory to review the region's earthquake regulations and disaster response plans.