Maximum likelihood solutions for layer parameters based on dynamic surface wave spectra

The paper outlines a probabilistic basis for the automatic estimation from observed surface wave dispersion of structural model parameters with uncertainties. Given an earth model, a wave type and pertinent parameter values, the group velocity of seismic waves can be computed from theory as a function of frequency. Such a function may also be based on the dynamic spectrum representation of an earthquake with known distance and origin time. A likelihood function for the unknown parameters may then be constructed, the parameters estimated and uncertainties assessed. When appropriate, a joint solution may be determined by combining the likelihoods for several stations. The technique is illustrated for Rayleigh waves of the April 20, 1989 Siberian earthquake recorded by a long-period seismograph at the Uppsala, Sweden seismographic station. The purely continental path permits, for the sake of an inversion example, a simple crustal model inversion for three wave modes. © 1997 Elsevier Science B.V. Kevwords." Seismic waves; Earthquakes: Unknown parameters; Rayleigh waves; Siberian earthquake