Simultaneous Inference of Plate Boundary Stresses and Mantle Rheology Using Adjoints: Large-Scale Two-Dimensional Models

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Authors

Johann Rudi, Michael Gurnis, Georg Stadler

Abstract

Plate motions are a primary surface constraint on plate and mantle dynamics and rheology, plate boundary stresses, and the occurrence of great earthquakes. Within an optimization method, we use plate motion data to better constrain uncertain mantle parameters. For the optimization problem characterizing the maximum a posteriori rheological parameters we derive gradients using adjoints and expressions to approximate the posterior distributions for stresses within plate boundaries. We apply these methods to a 2-D cross section from the western to eastern Pacific, with temperature distributions and fault zone geometries developed primarily from seismic and plate motion data. We find that the best-fitting stress exponent, $n$, is about 2.8 and the yield stress about 100 MPa or less. The normal stress on the interplate fault zones is about 100 MPa and the shear stresses about 10 MPa or less.

DOI

https://doi.org/10.31223/X57H0R

Subjects

Earth Sciences, Geophysics and Seismology, Numerical Analysis and Scientific Computing

Keywords

Dates

Published: 2021-11-08 20:53

Last Updated: 2021-11-09 04:53

License

CC BY Attribution 4.0 International

Additional Metadata

Data Availability (Reason not available):
The authors declare that all other data supporting the findings of this study are available within the paper and its Supplementary Material files. The code (Rhea) used for the forward models and the inference is available upon request.

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