Basin structure and seismic vulnerability through multigeophysical methods in Chania-Souda Basin (Crete, Greece)

This study presents the results of a multigeophysical survey in the Chania-Souda Basin, southwestern Crete (Greece), a rapidly expanding urban area, within one of the most seismically active regions of the Mediterranean. The aim was to constrain subsurface stratigraphy, basin structure, and seismic site response by integrating complementary geophysical methods. The investigation combined transient electromagnetic (TEM) soundings, multichannel analysis of surface waves (MASW), horizontal-to-vertical spectral ratio (HVSR) microtremor measurements, and passive seismic array techniques (SPAC and MAM), supplemented by borehole information and regional geological mapping. The collected data enabled the construction of pseudo-2D resistivity cross-sections and the estimation of shear wave velocity (Vs) profiles, which helped infer lithological layering, identify key stratigraphic units, and reveal at least three distinct fracture zones generally aligned along E -W, N-S, and NW-SE directions. These features partially correlate with previously mapped tectonic structures and reveal new fault zones that were not previously identified. The geophysical interpretations are consistent with borehole logs and regional stratigraphy, confirming the effectiveness of the integrated approach in resolving subsurface complexity. Seismic response parameters correlate spatially with zones of thick low-velocity sediments rather than with lithology alone. Overall, this study demonstrates that integrating complementary near-surface geophysical methods substantially improves subsurface resolution and reduces interpretational ambiguity in complex sub-urban basins, providing a stronger basis for tectonic assessment and seismic-hazard-related applications.