De Plaen, Raphael ; Garcia-Fernandez, Mariano ; Van Noten, Koen ; Jimenez, Maria-Jose ; Sakellariou, Nikolaos ; Kouskouna, Vasiliki ; Lecocq, Thomas ; Rodriguez-Diaz, Sara ; Galanos, Nikolaos

Poster presented at IAGA/IASPEI, Lissabon, Portugal on 2025-09-04

Abstract: The Paliki Peninsula of the Ionian Kefalonia Island (Greece) is located in one of the most active seismotectonic regions of the Mediterranean Sea, east of the major Kefalonia-Lefkada transform fault. Paliki has been repeatedly hit by moderate to large earthquakes up to Mw 7.0. A joint geophysical field campaign was organized in 2024 to develop a new 3D subsurface model for understanding site effects and to compute a more detailed velocity model for accurately locating earthquakes. Eight cross-profiles and one array were installed on Paliki, using 27 SmartSolo 3C nodes and two Tromino instruments. Ambient noise measurements were carried out at 220 locations, resulting in a total of 3225 hours of continuous data.Several small earthquakes were recorded that could not be located with the permanent seismic network alone. Array- , cross-correlation and Horizontal to Vertical Spectral Ratio (HVSR) techniques were applied to model the sedimentary cover and the variation in bedrock depth. Array data were processed with fk and inverted using dinver. Preliminary results show increasing thickness of Miocene marls deposits from west to east, overlaying a bedrock of Eocene limestones deeping to several hundreds of meters deep towards the eastern shoreline of the peninsula. To our knowledge, this is the first time that such large-scale fieldwork has been performed on an Ionian Island and the recorded data will stimulate new research studies, contributing significantly to more precise earthquake locations, and more accurate future local hazard assessments and risks evaluations.

Keyword(s): HVSR ; fk-analysis ; site effects ; Kefalonia