Transdimensional Bayesian Receiver Function Migration for 3-D TTI Structure
Abstract
Recent studies have applied transdimensional Bayesian methods to estimate the anisotropic properties of the crust and mantle beneath individual seismic stations from receiver functions, often in combination with other seismic observables. Although these inversions excel at recovering the 1-D structure and its uncertainty, they often fail to utilize data from neighboring stations and overlook potential tradeoffs between dipping and anisotropic structure. Where denser observations are available, migration and waveform inversion allow for better estimation of small-scale topography and lateral variation in the properties. For this reason, we extend the method of Burdick, Myers, & Brownlee (2018) to invert array receiver function data for 2- or 3-D anisotropic structure within the transdimensional Bayesian framework.
Radial and transverse receiver function data are modeled by applying a forward scattering operator on a discontinuity model defined by differencing adjacent layers of constant TTI elastic properties. The misfit function based on receiver function waveform and azimuthal harmonic decomposition is then assessed, and the model is updated via reversible-jump Markov chain Monte Carlo. The number, elastic properties, and topography of model parameters are allowed to vary within the algorithm. The final output is an ensemble of models that can be evaluated for posterior distributions in depth and dip of discontinuities and tilted transverse anisotropic velocity. This approach holds several advantages over straightforward migration. First, the framework allows multiple phases and other meaningful observables to be simultaneously incorporated. Next, priors can be placed on the geometry and complexity of the discontinuity structure, reducing artifacts introduced by distribution. Finally, we also include empirically-derived constraints on elastic tensors as prior information. We present methodological developments and application to synthetics and real data observations to distinguish between models of crustal deformation in the Northern Appalachians.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.S43A..02B
- Keywords:
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- 7203 Body waves;
- SEISMOLOGY;
- 7255 Surface waves and free oscillations;
- SEISMOLOGY;
- 7299 General or miscellaneous;
- SEISMOLOGY