GNGTS 2015 - Atti del 34° Convegno Nazionale

134 GNGTS 2015 S essione 3.3 Conclusions. We described a method that allow to eliminate (or at least reduce) semblance manual picking. We developed a data driven V RMS model building strategy that automatically pick velocity profiles giving flat CRP events. This is done by means of an iterative matching pursuit approach that allow to preliminarily discharge invalid outliers leading to a performing solution. Results obtained from Pluto data set show that V RMS builder allow to obtain good results also in complex velocity model scenarios with a consequent improving for the imaging. Acknowledgements. The authors would like to thank Nicola Bienati (Eni Upstream and Technical Services) for fruitful discussions and the SMAART JV for providing the Pluto dataset. References Alkhalifah T.; 1997: Velocity analysis using nonhyperbolic moveout in transversely isotropic media . Geophysics, 62 , pp. 1839-1854. Alkhalifah T. and Tsvankin I.; 1995: Velocity analysis for transversely isotropic media . Geophysics, 60 , pp. 1550– 1566. Biondi B; 2006: 3D seismic imaging . Society of Exploration Geophysicists, 14 , pp. 147. Buland A., Kolbjørnsen, O., and Carter, A. J.; 2011: Bayesian dix inversion . Geophysics, 76 , pp. R15-R22. Candès E. J., Romberg J. K. and Tao, T.; 2006: Stable signal recovery from incomplete and inaccurate measurements . Communications on pure and applied mathematics, 59 , pp. 1207-1223. Claerbout, J.; 1985: Imaging the earth’s interior . Blackwell Scientific Publications, Fomel, S.; 2009: Velocity analysis using AB semblance. Geophysical Prospecting, 57 , pp. 311–321. Hastie T., Tibshirani R. and Wainwright M; 2015: Statistical Learning with Sparsity: The Lasso and Generalizations . Chapman & Hall/CRC Monographs on Statistics and Applied Probability, 143 , pp. 83. Jones, I. F.; 2010: Tutorial: Velocity estimation via ray-based tomography First Break vol. 28 , February 2010 Li Y. E. and Biondi B.; 2009: Automatic velocity picking by simulated annealing . Stanford Exploration Project, 138 , 1–10. Li Y. E. and Biondi B.; 2011: Migration velocity analysis for anisotropic models . 2011 SEGAnnual Meeting. Society of Exploration Geophysicists. Neidell N. S. and Taner M. T.; 1971: Semblance and other coherency measures for multichannel data . Geophysics, 36 , pp. 482-497. Sarkar D., Baumel R. T. and Larner K. L.; 2002: Velocity analysis in the presence of amplitude variation : Geophysics, 67 , pp. 1664-1672. Sarkar D., Castagna J. P. and Lamb W.; 2001: AVO and velocity analysis : Geophysics, 66 , 1284-1293. Taner M. T. and Koehler F.; 1969: Velocity spectra-digital computer derivation applications of velocity functions . Geophysics, 34 , pp. 859-881. Toldi, J. L.; 1989: Velocity analysis without picking . Geophysics, 54 , pp. 191-199. Vieira, W. W., Leite, L. W. and Nunes, F. S.; 2011: Automatic Picking in the Semblance Domain . 12th International Congress of the Brazilian Geophysical Society. Yilmaz Ö.; 2001: Seismic data analysis . Society of Exploration Geophysicists, vol. I , pp. 292) Less is more: from van der Rohe to the 4-channel system for the efficient and holistic acquisition of surface waves: An urban case study G. Dal Moro 1* , S.R. Moustafa 2,3 , N. Al-Arifi 2 1 Department of Seismotectonics, Institute of Rock Structure and Mechanics, Prague, Czech Republic 2 Geology and Geophysics Department, Faculty of Sciences, King Saud University, Riyadh, Saudi Arabia 3 Seismology Dept., National Research Institute of Astronomy and Geophysics, Cairo, Egypt Introduction. Nowadays, the analysis of surface wave propagation for depicting the shear- wave velocity (V S ) vertical profile is routinely performed for a large number of applications ranging from crustal studies to Non-Destructive Testing (e.g. Ryden et al. , 2004; Prodehl et al. ,