An Updated Earthquake Catalogue in Crete Derived by the Development of Local 1D Velocity Models and Hypocentre Relocation

Abstract

Crete is located in the Southern Aegean, in the southernmost part of the Hellenic Trench. Given the large number of earthquakes in the region generated by the convergence of the Eurasian and African tectonic plates, the research area is critical. More than 7000 manually revised events from 2018 to 2023 were used in this work to construct local 1D velocity models of Crete and the neighbouring areas. The P-wave velocity models were constructed using the spatiotemporal error minimisation method estimated using the HYPOINVERSE algorithm. At the same time, the VP/VS ratio was obtained using the Chatelain method, which compares the time difference in P and S phases recorded by pairs of corresponding stations. We then relocated the seismicity of the study area that was recorded by both permanent and temporary seismic networks during the abovementioned period. The double-difference algorithm was used to relocate events with magnitudes above the magnitude of completeness, resulting in more than 4500 precise relative locations with horizontal and vertical uncertainties of less than 2.5 km. The precise locations delineated faults both on the island and in the offshore study area. Furthermore, the results are discussed and compared with the ones derived from other significant previous works presented recently. The final dataset analysis contributes to a better understanding of the research area’s seismicity as triggered by local and regional tectonic structures.