1. WP-1-1: Methodological improvements for 3D reconstructions Contributors: Pierre Gouédard, Philippe Roux, Seiji Tsuno, Marc Wathelet

2. What has been done/initiated ? ESG2006 noise blind test  Estimation of dispersion curves is OK  Interpretation of mode branches and inversion of Vs profiles are critical issues Comparison between SPAC/FK et noise correlation techniques => performance and limits of these “competing” approaches => what kind of “correlation technique and array layout” to use for imaging subsurface shear-wave velocity MASW measurements for getting information on the shallow layers (Vs, Qs)  high frequency technique (10-80 Hz)  complementary to noise array technique

3. Comparison between SPAC/FK and noise correlation

5. resolution limit D ~ max aliasing limit 2d ~ min

6. resolution limit D ~ max aliasing limit 2d ~ min reliable Mapping resolution and aliasing limits into f-c domain

7. Isotropic noise directional noise

8. HRFK CORR

9. Comparison SPAC/FK and noise correlation Similar performance at low frequency (controlled by array aperture) Better performance of noise correlation at high frequency (although a similar array layout, effective spatial aliasing is different) Noise correlation allows estimating both Rayleigh and Love waves dispersion curves (also for SPAC3C but not so straightforwardly for FK techniques) Future studies on performance of correlation techniques application of correlation to 2D structures (array aperture  frequency range  2D site)