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Accounting for uncertain 3-D elastic structure in fault slip estimates

Ragon, Théa and Simons, Mark (2021) Accounting for uncertain 3-D elastic structure in fault slip estimates. Geophysical Journal International, 224 (2). pp. 1404-1421. ISSN 0956-540X.

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Earthquake source estimates are affected by many types of uncertainties, deriving from observational errors, modelling choices and our simplified description of the Earth’s interior. While observational errors are often accounted for, epistemic uncertainties, which stem from our imperfect description of the forward model, are usually neglected. In particular, 3-D variations in crustal properties are rarely considered. 3-D crustal heterogeneity is known to largely affect estimates of the seismic source, using either geodetic or seismic data. Here, we use a perturbation approach to investigate, and account for, the impact of epistemic uncertainties related to 3-D variations of the mechanical properties of the crust. We validate our approach using a Bayesian sampling procedure applied to synthetic geodetic data generated from 2-D and 3-D finite-fault models. We show that accounting for uncertainties in crustal structure systematically increases the reliability of source estimates.

Item Type:Article
Related URLs:
URLURL TypeDescription ItemAlTar2 package ItemClassic Slip Inversion
https://www.paraview.orgRelated ItemParaView/VTK
Ragon, Théa0000-0002-1276-1910
Simons, Mark0000-0003-1412-6395
Additional Information:© The Author(s) 2020. Published by Oxford University Press on behalf of The Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2020 November 1. Received 2020 September 10; in original form 2020 June 30. Published: 04 November 2020. We are grateful to Charles Williams and an anonymous reviewer for their suggestions that helped improve the manuscript. The Bayesian simulations were performed with the AlTar2 package ( The Classic Slip Inversion (CSI, Python library (Jolivet et al. 2014) developed by Romain Jolivet was used to build inputs for the Bayesian algorithm. The meshes for the FEM simulations were built using Los Alamos Grid Toolbox (LaGriT, 2013) and will be shared on request to the corresponding author. We used the finite-element code Pylith (Aagaard et al. 2013) to perform the simulations. 3-D inputs were visualized using the open-source parallel visualization software ParaView/VTK ( Figures were generated with the Matplotlib and Seaborn (doi:10.5281/zenodo.1313201) Python libraries. MS was partially supported by the National Aeronautics and Space Administration under Grant No. 80NSSC19K1499.
Group:Seismological Laboratory
Funding AgencyGrant Number
Subject Keywords:Inverse theory; Probability distributions; Earthquake source observations
Issue or Number:2
Record Number:CaltechAUTHORS:20210225-071449096
Persistent URL:
Official Citation:Théa Ragon, Mark Simons, Accounting for uncertain 3-D elastic structure in fault slip estimates, Geophysical Journal International, Volume 224, Issue 2, February 2021, Pages 1404–1421,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108189
Deposited By: Tony Diaz
Deposited On:25 Feb 2021 17:03
Last Modified:25 Feb 2021 17:03

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