Exploring the Lake Hazar (Elazığ-Turkey) Basin Geometry with Vertical Prismatic Polyhedra

The Lake Hazar pull-apart basin, situated along the East Anatolian Fault System, represents a key tectonic structure within one of Turkey's most active seismic zones. This fault system recently generated two catastrophic M7.0+ earthquakes in February 2023, underscoring the importance of understanding its associated geological features. Gravity modeling offers a powerful tool for exploring such basins, providing insights into subsurface geometry and tectonic processes.

This study employs vertical prismatic polyhedra to model the basin. Conventional modelling methods often require a trade-off between computational efficiency and data resolution, either overloading calculations with unnecessary prisms or losing critical detail with coarse sampling. By integrating Voronoi diagrams into the modeling process, we achieve sensitivity to data sampling frequency while maintaining computational efficiency and preserving accuracy.

Approximately 600 newly collected gravity data points from the Sivrice and Gezin provinces were used to construct the two-layer models. Forward modeling with a constant density contrast yielded basin geometries to a maximum depth of 350 meters, achieving root-mean-square errors below 0.1 mGals. Beyond refining the 3D basin structure, this method allowed us to estimate excess mass within different sections, providing additional constraints on sedimentary characteristics and tectonic activity in the region.

Comparison with our previous 2D-to-quasi-3D Talwani models revealed consistent results, including similar sediment thickness variations. However, the vertical prismatic polyhedra method demonstrated superior adaptability to irregularly spaced data and greater computational efficiency, making it especially suitable for complex tectonic environments like the Lake Hazar region. The integration of computationally efficient methods highlights the potential for future applications in similar tectonic settings, advancing our ability to investigate fault-controlled basins in active seismic regions.