The Active Fault Database of Türkiye: Framework, Methodology, and Ongoing Revisions by the General Directorate of Mineral Research and Exploration (MTA

Active fault mapping and fault databases are fundamental components of seismic hazard assessment, land-use planning, and disaster risk reduction in tectonically active regions. The effectiveness of such databases critically depends on their ability to integrate paleoseismological evidence, surface rupture observations, and consistent fault characterization across multiple spatial scales. Türkiye, located within the actively deforming Alpine–Himalayan orogenic belt, provides an important natural laboratory for evaluating how national-scale active fault databases can be systematically updated and improved.The General Directorate of Mineral Research and Exploration (MTA), the national geological survey of Türkiye, has conducted active fault and paleoseismological investigations since the 1970s. These efforts led to the publication of successive editions of the Active Fault Map of Türkiye, first at a scale of 1:1.000,000 in 1992 and later updated to 1:1.250.000 in 2013 following the 1999 Gölcük (Mw 7.4) and Düzce (Mw 7.2) earthquakes. The 2013 map has since served as the primary reference for seismic hazard studies in Türkiye.Within the framework of nationwide paleoseismology and crustal research projects, trench-based investigations had been completed by the end of 2025 on approximately 250 faults or fault segments included in the 2013 database. These studies resulted in revised fault activity classifications, updated segmentation models, and the identification of nearly 100 previously unmapped active faults. In addition, major surface-rupturing earthquakes, including the 2020 Sivrice (Mw 6.8) event and the catastrophic 2023 Kahramanmaraş doublet earthquakes (Mw 7.8 and Mw 7.6), produced more than 600 km of surface ruptures that were systematically documented and mapped by MTA.In order to incorporate these new datasets, MTA conducted the “Revision and Improvement of the Active Fault Map of Türkiye Project” between 2022 and 2025. This project integrated paleoseismological data, detailed surface rupture mapping, and 1:25.000-scale active fault maps into a unified digital Active Fault Database. The resulting 1:1,000,000-scale Active Fault Map of Türkiye was generated through the digitization and integration of high-resolution fault data.This contribution presents the methodological framework, data structure, and revision strategy of the Active Fault Database of Türkiye, emphasizing approaches that are applicable to other tectonically active regions worldwide. The results demonstrate how integrating paleoseismology, earthquake surface ruptures, and multi-scale fault mapping significantly enhances the reliability of active fault databases, with direct implications for seismic hazard assessment, urban resilience, and disaster risk mitigation in regions affected by distributed deformation.