A new misfit function for multimodal inversion of surface waves

Higher-modecontributionisimportantinsurface-waveinversion because it allows more information to be exploited, increases investigation depth, and improves model resolution. A new misfit function for multimodal inversion of surface waves, based on the Haskell-Thomson matrix method, allows higher modes to be taken into account without the needtoassociateexperimentaldatapointstoaspecificmode, thus avoiding mode-misidentification errors in the retrieved velocity profiles. Computing cost is reduced by avoiding the need for calculating synthetic apparent or modal dispersion curves.Basedonseveralsyntheticandrealexampleswithinversion results from the classical and the proposed methods, wefind that correct velocity models can be retrieved through the multimodal inversion when higher modes are superimposedintheapparentdispersion-curveorwhenitisnottrivial todetermineaprioritowhichmodeeachdatapointoftheexperimental dispersion curve belongs. The main drawback of the method is related to the presence of several local minima inthemisfitfunction.Thisfeaturemakesthechoiceofaconsistentinitialmodelveryimportant.

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