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WP-1-1: Methodological improvements for 3D reconstructions. Contributors: Pierre Gouédard, Philippe Roux, Seiji Tsuno, Marc Wathelet. What has been done/initiated ? ESG2006 noise blind test Estimation of dispersion curves is OK Interpretation of mode branches and inversion of Vs profiles
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WP-1-1: Methodological improvements for 3D reconstructions Contributors: Pierre Gouédard, Philippe Roux, Seiji Tsuno, Marc Wathelet
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
Comparison between SPAC/FK and noise correlation
resolution limit D ~ max aliasing limit 2d ~ min
reliable resolution limit D ~ max Mapping resolution and aliasing limits into f-c domain aliasing limit 2d ~ min
Isotropic noise directional noise
HRFK CORR
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)