Estimation of Basement Relief in the Isparta Basin by Applying Spectral Filtering and Local Optimisation-Based Inversion Techniques to Gravity Data

Abstract

The Isparta Basin is a tectonically complex depression situated at the junction between the Western Anatolian extensional province and the Tauride orogenic belt. It lies near the intersection of the Hellenic and Cyprus arcs, forming the Isparta Angle. This transitional zone is characterised by intense crustal deformation, complex fault systems, and active seismicity, making it a key area for geophysical investigation. Microgravity anomalies were analysed to assess the thickness of the basin's sedimentary deposits. A 2-D Fourier transformation-based procedure was used to decompose the gravity data into regional and residual components. This spectral filtering step isolated shallow subsurface signals from broader tectonic influences, thereby providing a robust foundation for depth modelling by enhancing the resolution of near-surface features that are often masked by deeper structural trends. Residual gravity anomalies were further examined using both 2-D and 3-D local optimisation-based inversion techniques. These complementary methods allowed for cross-validation of results mathematically and improved confidence in the derived structural interpretations. The resulting basement depth estimates demonstrate consistency and align well with the established geological framework of the Isparta Basin, including known fault geometries and stratigraphic boundaries, with the inversion results indicating maximum sedimentary fill thickness of approximately 0.53 km. This result has practical implications for disaster management, particularly in assessing the potential for seismic amplification. Thick sedimentary sequences can substantially affect ground-motion characteristics during earthquakes, especially within basin environments. Therefore, mapping the spatial distribution of sedimentary accumulation contributes to more informed regional risk assessments and supports the development of targeted mitigation strategies. These findings are expected to provide valuable input for land-use planning and infrastructure resilience in the Isparta Basin, offering essential baseline information for authorities and engineers involved in seismic hazard mitigation.