Ambient noise modelling of the subsurface structure along two profiles in Paliki Peninsula, Cephalonia, Greece

Abstract Paliki Peninsula, on Cephalonia Island, is one of the most seismically active areas in Europe, east of the major Cephalonia transform fault. In 1953, a series of three major earthquakes, Mw 5.9, Mw 6.6, and Mw 7.0, produced extensive damage in Cephalonia. More recently, in 2014, a sequence with two main shocks (~ Mw 6.0) caused considerable damage. We integrated a geological and geotechnical dataset from existing sources and used it together with ambient-noise records to study the subsurface structure of Paliki Peninsula along two E-W profiles, crossing the central (13 sites) and southern (seven sites) parts of the peninsula. We combined fundamental frequency microtremor horizontal-to-vertical spectral ratios (MHVSR) and shear-wave velocity, as derived empirically from borehole geotechnical parameters data and, in some cases, from literature, with forward modelling of MHVSR curves, to obtain 2D images of the subsurface structure along the profiles. The depth to the bedrock (Eocene limestones) reach maximum values of 300–450 m to the eastern end of the two profiles, with three overlying soil formations on top of the bedrock: (i) Holocene deposits 2–4 m thick, (ii) Marine deposits, with thicknesses of 4–30 m, and (iii) Marls of varying thicknesses increasing from West to East, with steeper slope in the central profile near the coast. This preliminary image of the subsurface structure of Paliki Peninsula will contribute to a better understanding of local tectonics, earthquake sources, local/path propagation effects, and for improved local seismic hazard assessments and risk mitigation plans.