Combining automatic detection of maximum gravity gradients with seismology and geodetic data to illuminate the crustal architecture of the Mediterranean

The Mediterranean constitutes a complex plate boundary between converging continental plates marked by a wide range of deformation mechanisms, the presence of multiple micro-blocks, and extensional and compressional tectonics. While seismicity and surface kinematics from geodesy highlight (onshore) active plate boundaries and faults, we mostly rely on bathymetry to identify offshore tectonic segmentation. In this work, we explore the potential of automatic detection of maximum gravity gradients to complement our existing seismotectonic databases.

We present a holistic examination of the Mediterranean that integrates gravity, seismology and geodesy to localize weak zones and how they align with the current seismicity and highly-strained areas. We first extracted linear geological features and calculated the Moho depth from Bouguer and free-air anomaly gravity data through gradient computations and minimum-structure inversion modelling, respectively. Then, we synthesized published seismic catalogs, focal mechanisms and surface deformation rates to qualitatively assess the state of crustal stress/strain. We also included a quantitative approach that makes use of clustering. Areas bounded by large-scale gravitational lineaments that agree with large-scale faults and potential kinematic boundaries were classified as tectonic units.

Seismicity, geodesy and delineated maximum gravity gradients agree – to first order – well in highlighting the tectonic boundaries in the region. The maximum gravity gradients showed high potential in accentuating some overprinted/inherited geological structures in the eastern Mediterranean and particularly identified the fault system separating the West Anatolian Graben System and the Cyprian unit, the Aksu-Dinar fault system, which was found to extend to Samsun, Northern Türkiye. We also reproduce the full stretch of the South Levantine Sea fault system whose western end only was previously identified as the North Cyrenaica fault system. While more prominent in Northern Türkiye, the North Anatolian Fault zone was found to extend from Kermanshah, Iran to Vasilevo, Macedonia, covering about 2473 km.

This project has received funding from the European Union's Horizon Europe research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 101180812.