Crustal structure and dynamics in southeastern Sicily (Italy) by using seismological data.

Abstract

Introduction: Through receiver function analysis, this study inquires into some of the most basic properties of the crust below southeastern Sicily (Italy), mostly represented by the Hyblean Plateau. Method: This is accomplished, using P-to-S receiver function (P-RF) technique which involves coordinate rotation and deconvolution, by stacking waveforms from 335 teleseismic events, magnitude 6.0 and larger, to determine the delay in arrival time for several phases of the P-wave coda, relative to the initial P-wave arrival. This information is used to establish a linear relationship between thickness and VP/VS ratio, each of which is stacked using the slant stacking approach for a given station to identify the best-fit thickness and wave speed for the crust below that station. To determine their accuracy these results are compared with previous studies, as well as with synthetically generated receiver functions based on 1D crustal models including dipping layers. Results: The good regional coverage and the fairly dense station spacing (~20 km) leaded to a fairly complete image of the crust-mantle boundary over the entire region that shows strong lateral variations of the crustal thickness with Moho depth varying between 29 and 38 km. In particular, a thinner crust is observed in the central-eastern part of the Hyblean Foreland beneath SSY (Solarino) station and thickening further to the south beneath HMDC (Modica) station (up to 38 km) and to the north beneath HLNI (Lentini) station (up to 35 km). Sharp transitions between thinned and thickened crust are most likely the result of complicated 3D structures attributed to regional geodynamics. Discussion: Since all the 8 considered broadband stations lie in a geodinamically complex area, reliable estimates of the crustal thicknesses below these stations are key requisite for understanding the geologic and tectonic processes that have been dominant in the region, providing valuable information for the numerous earth science disciplines.