Determination of strain rates on the orta fault with geodetic observations

This study aims to determine the tectonic movements of the Orta (Dodurga) Fault, located in the Orta district of Çankırı, where the number of studies in the literature is limited and geodetic data remain insufficient. Seismic activity in the Çankırı region has been increasing over time. Therefore, a GNSS network consisting of 15 sites were established to represent the Orta Fault and its surroundings. The processing of data obtained from four GNSS campaign-style measurements conducted between November 2023 and August 2025 enabled the calculation of the contemporary velocity field of the Orta Fault. Taking the Eurasian plate as a constant reference, a westward motion of 15–20 mm/yr was identified in the study area. Analysis of the strain field derived from these velocity data revealed predominantly NE–SW extensional and NW–SE compressional patterns. Extension values increase from the southeast to the northwest of the study area, whereas compression exhibits the opposite trend. When the results are compared with the focal mechanism solution of the 2000 Orta–Çankırı earthquake (Mw 6.0), a strong consistency between the strain field and the focal mechanism is observed. Due to its earthquake-generating potential and its proximity to Ankara, which is located only 50–70 km away and hosts a population of more than 5 million, the Orta Fault represents a critical seismic risk for the region. Therefore, in addition to existing studies on velocity and strain fields, it is essential to determine strain accumulation along this fault with much higher accuracy. This will allow the estimation of key parameters such as recurrence periods and potential magnitudes of future earthquakes. Considering that the strain values obtained in this study, which provide preliminary quantitative findings regarding the seismic potential of the Orta Fault and its surroundings, are relatively high for the region, it is concluded that more reliable results on seismic risk can be achieved through future studies incorporating a spatially wider geodetic network.