Influence of structural inheritance along the Çardak fault on the Mw7.6 Elbistan earthquake rupture, southeastern Türkiye

Caden J. Howlett, Alexis K. Ault, Leslie Garcia, Dennis L. Newell, & Musa Balkaya

Submitted September 7, 2025, SCEC Contribution #14640, 2025 SCEC Annual Meeting Poster #TBD

Long-term (10-100 Myr) regional tectonic processes influence subsequent fault zone development and evolution. Preexisting, basement-hosted structures, fabrics, and slip surfaces can act as zones of weakness that facilitate strain localization over multiple earthquake cycles. Here we evaluate if and characterize how structural “inheritance” provides a first order control on modern rupture location and behavior of large magnitude continental strike-slip earthquakes. We report preliminary field observations from the Çardak fault system and the 2023 Mw 7.6 Elbistan earthquake surface rupture in the context of a regional tectono-magmatic synthesis. The conjunction of certain tectonic elements in Eastern Anatolia (southeastern Türkiye) and bedrock exposure surrounding the Çardak fault system provides an ideal setting to assess these relationships.

The region’s tectonic history is characterized by the opening and closure of remnant oceanic basins via northward subduction, tightening sutures that were subsequently overridden by southward verging thrust sheets. This process produced a regional field relationship of dismembered ophiolite sequences (primarily sheared serpentinite mélange) juxtaposed with massive, variably metamorphosed carbonate strata. To first order, the Çardak fault parallels this ancient structural contact.

Numerous aspects of the Elbistan earthquake surface rupture support that inheritance from an older fault network influenced the rupture geometry and behavior. Near the epicenter, the hypocentral location relative to the surface rupture and three-dimensional rupture exposures indicate a northward dipping rupture geometry with strike-slip motion captured by mm- to cm-spaced slickenlines along the rupture interface. The rupture is locally characterized by a bi-material interface separating rocks of dramatically different age. West of the epicenter, the rupture is linear, sub-vertical, and exploits a well-defined fault with strong fabrics. On-going work involves cross section construction and magnetite (U-Th)/He thermochronology to determine the subsurface orientation and thermal history of rocks directly adjacent to the 2023 rupture. The similar scale, along-strike variations in fault dip, and presence of ancient subduction-related rock assemblages facilitate comparisons between the San Andreas and Çardak fault systems.

Key Words
Türkiye, regional tectonics, structural inheritance

Citation
Howlett, C. J., Ault, A. K., Garcia, L., Newell, D. L., & Balkaya, M. (2025, 09). Influence of structural inheritance along the Çardak fault on the Mw7.6 Elbistan earthquake rupture, southeastern Türkiye. Poster Presentation at 2025 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Geology