@article{GarofaloFotiHollenderetal.2016,
  author    = {Garofalo, F. and Foti, S. and Hollender, F. and Bard, Pierre-Yves and Cornou, C. and Cox, B. R. and Ohrnberger, Matthias and Sicilia, D. and Asten, M. and Di Giulio, G. and Forbriger, T. and Guillier, B. and Hayashi, K. and Martin, A. and Matsushima, Satoru and Mercerat, D. and Poggi, V. and Yamanaka, H.},
  title     = {InterPACIFIC project: Comparison of invasive and non-invasive methods for seismic site characterization. Part I: Intra-comparison of surface wave methods},
  series = {Soil Dynamics and Earthquake Engineering},
  volume    = {82},
  journal   = {Soil Dynamics and Earthquake Engineering},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0267-7261},
  doi       = {10.1016/j.soildyn.2015.12.010},
  pages     = {222 -- 240},
  year      = {2016},
  abstract  = {The main scope of the InterPACIFIC (Intercomparison of methods for site parameter and velocity profile characterization) project is to assess the reliability of in-hole and surface-wave methods, used for estimating shear wave velocity. Three test-sites with different subsurface conditions were chosen: a soft soil, a stiff soil and a rock outcrop. This paper reports the surface-wave methods results. Specifically 14 teams of expert users analysed the same experimental surface-wave datasets, consisting of both passive and active data. Each team adopted their own strategy to retrieve the dispersion curve and the shear-wave velocity profile at each site. Despite different approaches, the dispersion curves are quite in agreement with each other. Conversely, the shear-wave velocity profiles show a certain variability that increases in correspondence of major stratigraphic interfaces. This larger variability is mainly due to non-uniqueness of the solution and lateral variability. As expected, the observed variability in V-s,V-30 estimatesis small, as solution non-uniqueness plays a limited role. (C) 2015 Elsevier Ltd. All rights reserved.},
  language  = {en}
}
@article{WatheletGuillierRouxetal.2018,
  author    = {Wathelet, Marc and Guillier, B. and Roux, P. and Cornou, C. and Ohrnberger, Matthias},
  title     = {Rayleigh wave three-component beamforming},
  series = {Geophysical journal international},
  volume    = {215},
  journal   = {Geophysical journal international},
  number    = {1},
  publisher = {Oxford Univ. Press},
  address   = {Oxford},
  issn      = {0956-540X},
  doi       = {10.1093/gji/ggy286},
  pages     = {507 -- 523},
  year      = {2018},
  abstract  = {The variation of Rayleigh ellipticity versus frequency is gaining popularity in site characterization. It becomes a necessary observable to complement dispersion curves when inverting shear wave velocity profiles. Various methods have been proposed so far to extract polarization from ambient vibrations recorded on a single three-component station or with an array of three-component sensors. If only absolute values were recovered 10 yr ago, new array-based techniques were recently proposed with enhanced efficiencies providing also the ellipticity sign. With array processing, higher-order modes are often detected even in the ellipticity domain. We suggest to explore the properties of a high-resolution beamforming where radial and vertical components are explicitly included. If N is the number of three-component sensors, 2N x 2N cross-spectral density matrices are calculated for all presumed directions of propagation. They are built with N radial and N vertical channels. As a first approach, steering vectors are designed to fit with Rayleigh wave properties: the phase shift between radial and vertical components is either -Pi/2 or Pi/2. We show that neglecting the ellipticity tilt due to attenuation has only minor effects on the results. Additionally, we prove analytically that it is possible to retrieve the ellipticity value from the usual maximization of the high-resolution beam power. The method is tested on synthetic data sets and on experimental data. Both are reference sites already analysed by several authors. A detailed comparison with previous results on these cases is provided.},
  language  = {en}
}