GNGTS 2016 - Atti del 35° Convegno Nazionale

212 GNGTS 2016 S essione 1.2 In the present work we propose new 3D V P and V P /V S models and, for the first time, a 3D P-wave attenuation image (Q P ) for southeastern Sicily, obtained by using a large dataset of local seismic events that occurred in the time span 1994–2013. Measurements of attenuation of seismic waves are important indicators of Earth heterogeneities, not easily amenable to study using only seismic velocities (i.e., Fehler et al. , 1992; Mitchell, 1995). We used the SIMULPS12 (Thurber, 1983). algorithm to jointly invert a total of 4448 P and 2876 S absolute arrival times. Based on the P and S ray paths of the selected data obtained by Fig. 2 – V P /V S model resulting from the 3D inversion. S-N and W-E vertical sections along the traces reported at 0 km level are also shown. The zones with RDE ≥ 0.4 SF ≤ 3.5; DWS ≥ 100 are shown with thick black, dotted white and dashed white contour lines, respectively.