Estimating large-scale uncertainty in the context of full-waveform inversion

The uncertainty of model parameters obtained by full-waveform inversion can be determined from the hessian of the least-squares error functional. Because the hessian is generally too costly to compute and too large to be stored, a segmented representation of perturbations of the reconstructed subsurface model in the form of geological units is proposed. This enables the computation of the hessian and the related covariance matrix on a larger length scale. A synthetic 2-D isotropic elastic example illustrates how conditional and marginal uncertainties can be estimated for the properties per geological unit by themselves and in relation to other units. A discussion on how the chosen length scale affects the result is included.