## Özet

The subsurface shear-wave velocity (Vs) is considered to be a key parameter for site characterization and assessment of earthquake hazard because of its great influence on local ground-motion amplification. Array microtremor measurements are widely used for the estimation of shear-wave velocities. Compared to other methods such as frequency-wavenumber (f-k) methods, the spatial autocorrelation (SPAC) method requires fewer sensors and thus is relatively easier to implement and gives robust estimations of shear-wave velocity profiles for depths down to a few hundred meters. The quantity derived from observed data is the SPAC coefficient, which is a function of correlation distance, frequency and phase velocity. Generally, estimation of Vs profiles is a two stage process: Estimation of the dispersion data from the SPAC coefficients and inversion of the dispersion data for shear-wave velocity structure. In this study, instead of inverting dispersion curves, a more practical approach is used; that is, observed SPAC coefficients are directly inverted for the S-wave velocities. A synthetic case and a field data application are presented to test the potential of the inversion algorithm. We obtain an iterative damped least-squares solution with differential smoothing. The differential smoothing approach constrains the change in shear-wave velocities of the adjacent layers and thus stabilizes the inversion.

Orijinal dil | İngilizce |
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Sayfa (başlangıç-bitiş) | 613-624 |

Sayfa sayısı | 12 |

Dergi | Journal of Seismology |

Hacim | 15 |

Basın numarası | 4 |

DOI'lar | |

Yayın durumu | Yayınlandı - Eki 2011 |

### Finansman

Acknowledgements This research was supported in part by the Turkish National Union of Geodesy and Geophysics Research Fund (UDP04-03). The PS logging data used in our work were provided by the Istanbul Metropolitan Municipality. We would like to thank Dr. Serdar Özalaybey for his helpful contributions. Our special thanks go to Prof. Gülçin Özürlan Ag˘açgözgü. Without her encouragement, this work would not have been completed. Finally, we gratefully acknowledge the two anonymous reviewers for their valuable comments and suggestions that considerably improved our manuscript.

Finansörler | Finansör numarası |
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Turkish National Union of Geodesy and Geophysics Research Fund | UDP04-03 |