Improved Monte Carlo inversion of surface wave data

Abstract

Inversion of surface wave data suffers from solution non‐uniqueness and is hence strongly biased by the initial model. The Monte Carlo approach can handle this non‐uniqueness by evidencing the local minima but it is inefficient for high dimensionality problems and makes use of subjective criteria, such as misfit thresholds, to interpret the results. If a smart sampling of the model parameter space, which exploits scale properties of the modal curves, is introduced the method becomes more efficient and with respect to traditional global search methods it avoids the subjective use of control parameters that are barely related to the physical problem. The results are interpreted drawing inference by means of a statistical test that selects an ensemble of feasible shear wave velocity models according to data quality and model parameterization. Tests on synthetic data demonstrate that the application of scale properties concentrates the sampling of model parameter space in high probability density zones and makes it poorly sensitive to the initial boundary of the model parameters. Tests on synthetic and field data, where boreholes are available, prove that the statistical test selects final results that are consistent with the true model and which are sensitive to data quality. The implemented strategies make the Monte Carlo inversion efficient for practical applications and able to effectively retrieve subsoil models even in complex and challenging situations such as velocity inversions.

Comment on ‘Shear wave profiles from surface wave inversion: the impact of uncertainty on seismic site response analysis’

“…In Foti et al (2009) surface wave dispersion curves were inverted using a Monte Carlo inversion (Socco and Boiero, 2008) that selects a set of equivalent possible solutions through a statistical test. All the equivalent solutions were then used to compute the 1D seismic response of the site.…”

Source depopulation potential and surface-wave tomography using a crosscorrelation method in a scattering medium

“…There is growing interest in surface waves in seismic exploration, for instance for velocity analysis of the reservoir overburden (e.g., Campman and Riyanti, 2007;Socco and Boiero, 2008), and the GF reconstruction method can be used to enhance active source experiments. In this context, it is sometimes referred to as seismic interferometry.…”

Influence of a sedimentary basin infilling description on the 2-D P–SV wave propagation using linear and non-linear constitutive models

“…When using surface waves dispersion curves inversion, it is commonly hypothesized that S-wave velocity is constant in each layer (e.g. Socco & Boiero 2008) even if a gradient can be also implemented in each layer (e.g. Wathelet et al 2004).…”