| Title | Gradient-based shear-wave velocity parameterization in Bayesian inversion of surface-wave dispersion for earthquake site response |
| Author | Gosselin, J; Dosso, S; Cassidy, J F; Quijano, J E; Molnar, S |
| Source | 2016. |
| Year | 2016 |
| Alt Series | Earth Sciences Sector, Contribution Series 20160027 |
| Publisher | European Seismological Commission |
| Meeting | 35th General Assembly of the European Seismological Commission; Trieste; IT; September 4-11, 2016 |
| Document | serial |
| Lang. | English |
| Media | paper |
| File format | pdf |
| Subjects | tectonics; modelling; s waves; earthquakes; seismicity; seismic models; seismic surveys; seismic profiles; seismic surveys, ground; array seismology; Bayesian inversion |
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| Program | Western Canada Geohazards Project, Public Safety Geoscience |
| Abstract | Knowledge of near-surface properties of the soil column, in particular, the shear-wave velocity (Vs) profile over the upper 10s of metres, are important for characterizing the expected ground response
to earthquake shaking at a specific site. Non-invasive and passive methods based on recording ambient seismic noise are increasingly popular for estimating Vs structure with minimal cost and site disruption. This paper applies a fully nonlinear
Bayesian inversion methodology to estimate Vs profiles and uncertainties using surface-wave dispersion data processed from passive seismic array recordings. In the inversion, the Vs profile is parameterized using a Bernstein polynomial basis, which
efficiently characterizes general depth-dependent Vs gradients in the soil column. Bernstein polynomials provide a stable parameterization in that small perturbations to the model parameters (basis function coefficients) result in only small
perturbations to the Vs profile. Shear-wave velocity profiles and uncertainties are obtained from the velocity-depth marginal posterior probability density. These probabilistic Vs profile results allow for probabilistic estimates of site response
factors such as peak ground velocity/acceleration and VS30. This provides a quantitative assessment of the uncertainty in site response. This methodology is applied to synthetic scenarios as well as real passive seismic array recordings collected at
sites in British Columbia, Canada. |
| Summary | (Plain Language Summary, not published)
This study presents a new development in passive-source seismology that can be used to better assess local earthquake site response. We use seismic array
recordings (background noise) to determine shear wave velocity profiles a key parameter used in the National Building Code for seismic hazard calculations. Our new methodology is an improved inversion technique that allows for velocity gradients to
be incorporated in the earth model, rather than just simple velocity layers. To ground-truth our technique, we compare our inversion results with known velocity profiles from nearby boreholes. |
| GEOSCAN ID | 298719 |
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