ACTIVE FAULT AND PALEOSISMOLOGY RESEARCH

Earthquakes are natural disasters caused by geological processes. Our country is one of the countries in the world that experiences the most earthquakes due to its geological location. Since it is a geological occurrence, the General Directorate of MTA has done studies on earthquakes and earthquake geology since its inception, with several studies on the country's active tectonics and active faults that cause earthquakes. The Active Tectonics Research Unit of the Geological Research Department, Earth Dynamics Research and Evaluation Coordinatorship, conducts earthquake geology research. This unit's current research focuses on active fault mapping, identifying the structural and geometric aspects of faults, determining the maximum earthquake magnitudes they can produce, and using paleoseismological investigations to investigate previous earthquake behavior. The goal was to update the information on Turkey's Active Fault Map and to develop an active fault database that would be useful at the national level. The Active Tectonic Research Unit's major tasks include active fault and seismicity studies. Mapping of active faults with earthquake potential, paleoseismology, earthquake hazard assessments, and regional neotectonic mapping are all included in this scope .

Since its inception, the General Directorate of MTA has been producing geological data on earthquakes. Between 1935 and 1975, the majority of the research conducted at the institute was in the form of field studies following earthquakes. Since 1975, earthquake studies have been conducted within the General Directorate as part of Neo-tectonic research as well as the Turkey Active Faults and Seismicity Project in order to determine earthquake sources, active faults, and their earthquake potential. The Active Fault Map of Turkey, which was the result of a ten-year research project, was published in 1992.

This map and its accompanying report serve as the primary reference source for evaluating all active faults in the country that are the source of earthquakes, and it is a document that is regularly used in earthquake hazard analyses and scaled planning. During the preparation of the Turkey Earthquake Zones Map and related rules, which were put into action in 1996 by the Ministry of Public Works and Settlement (renamed Ministry Of Environment And URBANIZATION as of 2021 by an official decree) the map was used to determine earthquake source zones. Between 1992 and 1999, geological research initiatives were conducted to correct flaws in Turkey's Active Fault Map and to examine active faults in greater depth, with thorough field data obtained along the East Anatolian Fault and the North Anatolian Faults. Aside from that, thorough active fault mapping was carried out in the south and east of the Marmara Sea as part of the TÜBTAK organization's National Marine Geology Program, with the results compiled in studies and publications.

Following the 1999 earthquakes, our General Directorate’s Geological Studies Department implemented a research program specific to the region and began to implement various projects in this direction, due to the increased risk of a possible earthquake arising from a section of the North Anatolian Fault in the Marmara Sea. The plan of this program, which can be used on land or at sea, is to identify earthquake sources in the area and to generate the basic geological knowledge needed for studies that can be conducted to prepare for a probable earthquake.

The goal of the project Updating the Active Fault Map of Turkey and Establishing an Active Fault Database, which began in 2004 and ended in 2011, is to update the Active Fault Map of Turkey, which was first published in 1992, in order to conduct more detailed earthquake hazard analyses in light of current knowledge. The active faults in the country's geographical areas were mapped at a scale of 1:25,000 as part of the project, and an active fault database was produced. Users can view the active fault maps created in the project at scales of 1:250.000 and 1:1.000.000.

Tasks have been assigned to our institution as part of the National Earthquake Strategy and Action Plan (UDSEP-2023). Within the framework of these activities, we conduct paleoseismology, seismotectonics, and earthquake hazard research. Turkey Paleoseismology Research Project (2012-2023) was put into effect for the investigation of paleoseismological behavior of the faults in the country (occurrence period of old earthquakes, earthquake recurrence interval, slip rate, fracture length, earthquake magnitude, and so on) using updated active fault map information, in order to create the geological information. It was launched in 2013 with the goal of compiling the data into a national database and making it available for use in seismic hazard analyses. 

The Turkey Seismotectonic Map Project, which intends to explore Turkey's seismotectonic structure on a national scale between 2012 and 2013, has been implemented once again as part of UDSEP-2023, and the prepared seismotectonic maps have reached the printing stage. MTA's active fault maps are the foundation for a number of studies that will be conducted in order to limit earthquake damage. The Initiative of Updating the Earthquake Hazard Map of Turkey, which began in 2013 and is nearing completion, is another national project in this context in which our institution participated as a project partner (2015).

Following the conclusion of the aforementioned research programs, our General Directorate intends to implement the Paleoseismology of Turkey Active Faults Research Program in order to establish the geological information infrastructure needed to reduce earthquake damages as of 2012. By investigating the earthquake behavior of active faults in the recent geological past, data from paleoseismology research can be used to forecast future earthquake behaviors (occurrence period of old earthquakes, earthquake recurrence interval, slip rate, fracture length, earthquake magnitude, etc.). These are the fundamental inputs for a probabilistic seismic hazard analysis. According to the results of the Project of Updating the Active Fault Map of Turkey, project implementation will begin on faults that have priority in terms of earthquake danger. The project's outcomes will provide the geology and active fault data infrastructure needed to conduct more detailed earthquake hazard and risk analyses at both regional and local scales.