GNGTS 2019 - Atti del 38° Convegno Nazionale

570 GNGTS 2019 S essione 3.1 Note the improved S/N ratio on the final volume and the relevant enhancement of the coherency of the reflected events. Conclusions. We present the experience of seismic reflection data processing applied to 3D challenging data acquired for geothermal exploration. The first part of the workflow includes conservative operations aimed at increasing the signal-to-noise ratio and at preserving the reflected events. An F-XY was used to enhance the coherency of the reflections only at the end of the processing flow. However, the parameters adopted and the choice of their use after prestack weight application prevents the risk of introducing artefacts. The experience presented is part of a large project focused on the building of a velocity volume of P-waves (Tognarelli et al. , 2019), which will be used for depth migrate the seismic data. Acknowledgements. The authors wish to thank Enel Green Power for making the data available for permission to publish the results. Seismic data processing was carried out using ProMAX of Landmark Graphics Corporation, which is gratefully acknowledged. Part of this work was developed within the framework of the Research Projects of the University of Pisa (PRA 2018-2019), which we gratefully acknowledge. References Bertini, G., Casini, M., Giannelli, G. and Pandeli, E. ; 2006: Geological structures of a long-living geothermal system, Larderello, Italy . Terra Nova, 18, pp. 163-169, DOI 10.1111/j.1365-3121.2006.00676.x. Brogi, A. and Liotta, D.; 2006: Understanding the crustal structures of southern Tuscany: The contribution of the CROP18 Project . Bollettino di Geofisica Teorica e Applicata, 47, n0. 3, pp. 401-423. Tognarelli, A.; 2018a: The use of Continuous Wavelet Transform for Ground-Roll attenuation . 80th Annual International Meeting, EAGE, Expanded Abstracts, DOI 10.3997/2214-4609.201801417. Tognarelli, A.; 2018b: Comparison of Ground-Roll Attenuation Methods for Near Surface Investigations: 24th EuropeanMeeting of Environmental and Engineering Geophysics, EAGE, ExpandedAbstract, DOI 10.3997/2214- 4609.201802634. Tognarelli, A., Stucchi, E., Mazzotti, A.; 2019: Use of Global-Local FWI of seismic land data acquired in a geothermal exploration area. 1 st Conference on Geophysics for Geothermal and Renewable Energy Storage. EAGE, Expanded Abstract, DOI 10.3997/2214-4609.201902518. SEISMIC ATTENUATION IN THE TYRRHENIAN SEA: ESTIMATION OF CODA QUALITY FACTOR Q c C. Nardoni 1 , F. Cammarano 2 , L. De Siena 3 , E. Mattei 1 1 Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, Rome, Italy 2 Dipartimento di Scienze, Università degli Studi Roma Tre, Rome, Italy 3 Institute of Earth Sciences, Johannes Gutenberg University, Mainz, Germany Introduction. Seismic attenuation observations in combination with velocity tomography can provide important information about the structure of the Earth. The two main mechanisms of attenuation are anelastic absorption, that mainly depends on temperature, melt or fluid content, and chemical composition, and scattering of seismic waves due to small-scale velocity heterogeneities. Coda attenuation ( Q c –1 ) measurements are widely used in seismology for lithospheric attenuation studies and are based on a method developed by Aki and Chouet (1975). This technique can be applied in a uniform half-space in the approximation of a quasi-diffusive regime at long lapse time from the origin of the earthquakes, where ( Q c –1 ) provides a direct measurement of absorption. Coda attenuation imaging has been applied locally, i.e., in a region of relatively small extent surrounding the sources and stations, and at continental scale. For example, previous studies were able to characterize the volcanic structure in terms of fluid/melt accumulation and tectonics (De Siena et al. , 2017) and to map the absorption properties of the