1:45 PM - 2:00 PM
[SIT28-01] Trans-dimensional Bayesian inversion for the crust and upper mantle using Ps/Sp receiver functions and multi-mode surface waves
Keywords:Bayesian inversion, receiver function, surface wave, higher mode, lithosphere, asthenosphere
In this study, we develop a new method for non-linear joint inversion of Ps and Sp receiver functions and multi-mode surface waves, using trans-dimensional Bayesian formulation. This trans-dimensional approach quantitatively estimates the complexity of earth model, in which the number of model parameters (e.g. number of layers) is also treated as an unknown. The reversible-jump Markov Chain Monte Carlo approach is used to sample models with variable dimension in proportion to the posterior distribution of Earth models, which enables us to quantify the non-uniqueness of the solution.
For a 1-D layered S-wave speed model with several sharp velocity jumps, we performed synthetic tests for single-data inversions with each data type (Ps receiver functions, Sp receiver functions, and multi-mode Rayleigh waves) as well as joint inversions with several combinations of different types of data. Through the series of synthetic tests, we found that any single-data inversion cannot recover the given velocity model correctly, but the resolution of the model can be dramatically improved by simultaneously inverting body waves and surface waves. The joint inversion of the Sp receiver function and the multi-mode Rayleigh waves still poses weak uncertainty of about 3 km in the Moho depth, which can be better constrained by incorporating the Ps receiver function. For the number of layers, when we jointly invert the Ps receiver function and the multi-mode Rayleigh waves, the maximum probability exhibits one more layer added to the true number, which can be resolved better by incorporating the Sp receiver function. The velocity model can be best resolved if we invert all the three-types of data (Ps and Sp receiver functions, and multi-mode surface waves) simultaneously, which enables us to achieve a perfect recovery of all the unknowns.