• journal_title：Geophysics
• Contributor：Zacharie Duputel ; Michel Cara ; Luis Rivera ; Georges Herquel
• Publisher：Society of Exploration Geophysicists
• Date：2010-
• Format：text/html
• Language：en
• Identifier：10.1190/1.3341172
• journal_abbrev：Geophysics
• issn：0016-8033
• volume：75
• issue：2
• firstpage：R13
• section：SEISMIC INVERSION

Near-surface shear-velocity structure can be inferred from multimode dispersion data. Several methods have been developed to isolate the different modes from seismic signals observed on linear arrays of sensors. Most techniques analyze the wavefield through a frequency-wavenumber mula" id="inline-formula-1">mg class="math mml" alt="Formula" src="R13/embed/mml-math-1.gif" /> transform, paying little attention to group-delay-time information. Moreover, classical analyses are generally restricted to fundamental-mode dispersion, limiting the resolution power at depth. We have overcome the limitations of classical mula" id="inline-formula-2">mg class="math mml" alt="Formula" src="R13/embed/mml-math-2.gif" /> analysis by using a wavefield representation in the group-velocity/phase-velocity mula" id="inline-formula-3">mg class="math mml" alt="Formula" src="R13/embed/mml-math-3.gif" /> domain. We have then set up a nonlinear inversion procedure, easily tractable on a common field computer, to constrain the 1D vertical profile of shear velocities. Applications to synthetic data and to a set of actual records show that mula" id="inline-formula-4">mg class="math mml" alt="Formula" src="R13/embed/mml-math-4.gif" /> diagrams greatly help to separate dispersion information between different modes, even when they are not detectable on usual mula" id="inline-formula-5">mg class="math mml" alt="Formula" src="R13/embed/mml-math-5.gif" /> diagrams. Tests on synthetic and actual data confirm that the inversion procedure quickly converges to the expected model.