GNGTS 2018 - 37° Convegno Nazionale

GNGTS 2018 S essione 1.1 127 The results revealed a frequency (f) dependence of coda Q on the form Q C =Q 0 f n , over a wide frequency band. The Q C relationships obtained are Q C =(29±1.12)f (0.87±0.07) and Q C =(31±1.12) f (0.82±0.06) , for shallow and deep events, respectively. The value of the exponent n throughout the study region is greater than 0.8. This result is within expected values for highly heterogeneous, considerably tectonically complex and seismically active regions. Regionalization has been performed by applying Del Pezzo et al. (2016) technique, based on novel empirical space-weighting functions which separately describe the space sensitivity for both intrinsic (Q i ) and scattering (Q s ) attenuation. We arbitrarily extended its validity to coda Q (Giampiccolo and Tuvè, 2018), in the assumption that Q C is closer to Q i than to Q s (i.e. Frankel and Wennerberg 1987; Matsunami 1991; Wennerberg 1993) and we back-projected, through the weighting functions proposed by Del Pezzo et al. (2016), the obtained Q C values. The results of coda Q regionalization evidence spatial variation of seismic attenuation that could be attributed to the different geological characteristics and/or to a different tectonic and seismic behaviour. Moreover, the coda Q anomalies distribution highlights the structural contrasts already pointed out by velocity tomography studies (Scarfì et al., 2007; Musumeci et al. , 2014; Giampiccolo et al. , 2017). References Amato A., Azzara R., Basili A., Chiarabba C., Cocco M., Di Bona M. and Selvaggi, G.; 1995: Mainshock and aftershocks of the December 13, 1990, eastern Sicily earthquake . Ann. Geofis., 2 , 255–266. Azzaro R. and BarbanoM.S.; 2000: Analysys of the seismicity of southeastern Sicily: a proposed tectonic interpretation . Ann. Geophys., 43 , 171–188. Boschi E., Ferrari G., Gasperini P., Guidoboni E., Smriglio G. and Valensise G.; 1995: Catalogo Dei Forti Terremoti in Italia Dal 461 A.C. al 1980 . Istituto Nazionale di Geofisica, S.G.A., Roma. Del Pezzo E., Ibanez J., Prudencio J., Bianco, F. and De Siena L.; 2016: Absorption and Scattering 2D Volcano Images from Numerically Calculated Space-weighting functions . Geophys. J. Int., 206 , 742-756. doi: 10.1093/ gji/ggw171. Frankel A. and Wennerberg L.; 1987: Energy-flux model of seismic coda: separation of scattering and intrinsic attenuation. Bull. Seismol. Soc. Am., 77 , 1223–1251. Giampiccolo E., Brancato A., Manuella F.C., Carbone S., Gresta S. and Scribano V.; 2017: New evidence for the serpentinization of the Palaeozoic basement of southeastern Sicily from joint 3-D seismic velocity and attenuation tomography . Geophys. J. Int., 211 , 1375–1395. doi.org/10.1093/gji/ggx369. Giampiccolo E. and Tuvè T.; 2018: Regionalization and dependence of coda Q on frequency and lapse time in the seismically active Peloritani region (northeastern Sicily, Italy). Journal of Seismology, 22 (4), 1059-1074, doi. org/10.1007/s10950-018-9750-0. Matsunami K.; 1991: Laboratory tests of excitation and attenuation of coda waves using 2-D models of scattering media. Phys. Earth. Planet. Inter., 67 , 36–47. Monaco C., Tapponier P., Tortorici L. and Gillot P.Y.; 1997: Late Quaternary slip rates on the Acireale-Piedimonte normal faults and tectonic origin of Mt. Etna (Sicily). Earth Planet. Sci. Lett., 147 , 125-139. Musumeci C., Scarfì L., Palano M. and Patanè D.; 2014: Foreland segmentation along an active convergent margin: new constraints in southeastern Sicily (Italy) from seismic and geodetic observations. Tectonophysics, 630 , 137– 149. Sato H.; 1977: Energy propagation including scattering effects. Single isotropic scattering approximation. J. Phys. Earth., 25 , 27–41. Scarfì L., Giampiccolo E., Musumeci C., Patanè D. and Zhang H.; 2007: New insights on 3D crustal structure in southeastern Sicily (Italy) and tectonic implications from an adaptive mesh seismic tomography. Phys. Earth Planet. Inter., 161 , 74–85. Wennerberg, L.; 1993: Multiple-scattering interpretation of coda-Q measurements . Bull. Seismol. Soc. Am., 83 , 279–290.