Ground Penetrating Radar Survey Revealing Pre-Event Earthquakes on the 6 February 2023 Mw 7.5 Elbistan Earthquake Surface Rupture, Türkiye

Earthquakes occasionally rupture faults that were not previously recognised, raising the question of whether such structures represent newly formed faults or previously unidentified active faults with a history of repeated rupture. This debate is particularly relevant for the NE-striking eastern section of the 6 February 2023 M_w 7.5 Elbistan Earthquake rupture, referred to as the Yeşilyurt Fault. Unlike the better-known Çardak Fault to the west, the Yeşilyurt Fault was not mapped in the official Active Fault Map of Türkiye and lacks data regarding its paleoseismicity and morphotectonic evolution.

In this study, we introduce a novel, high-resolution, non-invasive, and relatively time- and cost-effective approach to investigate the rupture history at a surface-rupture site of the Elbistan earthquake. The method integrates unmanned aerial vehicle (UAV)–based topographic surveying with ground-penetrating radar (GPR) profiling across an earthquake surface rupture site. UAV surveys yielded high-resolution topography that reveals multiple surface-rupture strands. Some strands coincide with pre-existing topographic scarps, whereas others cut across bedrock highs. We then acquired three GPR profiles near the scarped area: two profiles crossing two parallel surface-rupture strands, and one profile oriented parallel to and between them (Figure 1). The GPR data image multiple pre-event offsets and deformation within late Quaternary sediments, indicating that the Yeşilyurt Fault at the study site has hosted multiple large earthquakes prior to the 2023 Elbistan event. Together, the UAV and GPR results suggest that the Yeşilyurt Fault at this location is a previously unidentified active fault segment rather than a newly generated fault. This study demonstrates the utility of combining UAV-based topography and GPR imaging for evaluating the activity and rupture history of “hidden” faults that emerge during large earthquakes.

Figure 1.  (a) Surface ruptures of the 2023 M_w 7.6 Elbistan earthquake superposed on the UAV DSM-based topographic map. Surface ruptures are constrained based on our field investigation and the UAV-derived DSM and orthoimage. The black rectangle shows the location of the study site (b and c). (b) The topographic map shows the study site and the locations of the GPR lines. Arrows show the GPR survey directions. (c) Geological interpretation of (b).