Multi-approach study for buried fault and its seismic risk assessment, Misis fault, Adana Türkiye

The inadequate characterization of buried faults may lead to unexpected damage resulting from the earthquakes they are capable of generating. Therefore, multi-disciplinary approaches that incorporate buried faults into seismic hazard and risk assessments have gained increasing attention both in national and international literature.  Post-earthquake investigations following the Van Earthquake and the 2023 Kahramanmaraş earthquakes in Türkiye indicate the necessity of characterization of tectonic structures.

This study aims to evaluate the potential buried continuation of the Misis Fault, one of the major elements influencing the structural evolution of the Adana Basin, based on geological and geophysical datasets. The investigation was carried out within the framework of the project entitled “Identification of Buried Faults Using Geophysical Methods”, conducted by the General Directorate of Mineral Research and Exploration (MTA) of Türkiye. The geometry and spatial spatial extent of the fault were examined using multiple geophysical methods.

During the investigation process, surface observations related to the fault were evaluated to interpret its kinematic characteristics and possible activity from the geological point of view. Drone-borne magnetic surveys, high-resolution UAV-derived orthophotos and 2D seismic reflection data were combined together in the segments where surface morphology are limited. As a result of the integrated evaluation of field studies and geophysical data, outcomes suggesting the presence of structural discontinuities responsible for deformation within the Quaternary basin fill that are not directly observable at the surface. These discontinuities indicate a northward continuation of the Misis Fault beneath the Adana Basin. Furthermore, a previously unrecognized structure striking approximately N20ºW was identified within the basin based on the seismic profiles and orthophoto analyses. This structure, named the Tumlu Segment, is interpreted as a newly segment of the Misis Fault System.

In summary, the combined geological and geophysical results provide new insights into the buried continuation of the Misis Fault within the Adana basin. This finding should contribute to regional-scale seismic hazard and risk assessments.

Keywords: Buried faults, 2D seismic reflection, Drone-borne magnetic survey, orthophoto, Adana Basin, Misis Fault, Tumlu Segment