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A spectral boundary-integral method for faults and fractures in a poroelastic solid: Simulations of a rate-and-state fault with dilatancy, compaction, and fluid injection

Heimisson, Elias Rafn and Liu, Shengduo and Lapusta, Nadia and Rudnicki, John (2022) A spectral boundary-integral method for faults and fractures in a poroelastic solid: Simulations of a rate-and-state fault with dilatancy, compaction, and fluid injection. . (Unpublished)

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Fluid-fault interactions result in many two-way coupled processes across a range of length scales, from the micron scale of the shear zone to the kilometer scale of the slip patch. The scale separation and complex coupling render fluid-fault interactions challenging to simulate, yet they are key for our understanding of experimental data and induced seismicity. Here we present spectral boundary-integral solutions for in-plane interface sliding and opening in a poroelastic solid. We solve for fault slip in the presence of rate-and-state frictional properties, inelastic dilatancy, injection, and the coupling of a shear zone and a diffusive poroelastic bulk. The shear localization zone is treated as having a finite width and non-constant pore pressure, albeit with a simplified mathematical representation. The dimension of the 2D plane strain problem is reduced to a 1D problem resulting in increased computational efficiency and incorporation of small-scale shear-zone physics into the boundary conditions. We apply the method to data from a fault injection experiment that has been previously studied with modeling. We explore the influence of bulk poroelastic response, bulk diffusivity in addition to inelastic dilatancy on fault slip during injection. Dilatancy not only alters drastically the stability of fault slip but also the nature of pore pressure evolution on the fault, causing significant deviation from the standard square-root-of-time diffusion. More surprisingly, varying the bulk's poroelastic response (by using different values of the undrained Poisson's ratio) and bulk hydraulic diffusivity can be as critical in determining rupture stability as the inelastic dilatancy.

Item Type:Report or Paper (Discussion Paper)
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URLURL TypeDescription Paper ItemJournal Article
Heimisson, Elias Rafn0000-0001-8342-7226
Lapusta, Nadia0000-0001-6558-0323
Rudnicki, John0000-0002-4258-8506
Additional Information:License: Attribution-NonCommercial-NoDerivatives 4.0 International. Version 1: Sat, 12 Feb 2022; Version 2: Mon, 8 Aug 2022. This study was supported by the Geophysics Option Postdoctoral Fellowship from the Division of Geological and Planetary Sciences at Caltech and ETH Postdoctoral fellowship (Project No. FEL-19 20-2) to E.R.H. The work was further supported by the NSF IUCRC Center for Geomechanics and Mitigation of Geohazards (projects GMG-4.1, GMG-4.2) to N.L. Data Availability Statement: No original data is presented in this study. The data used in regard to application to the (Guglielmi et al., 2015) field experiment was archived by Larochelle et al. (2021b): CatechDATA repository ( The software implementation of the method described in this paper is available here (see Heimisson, 2022).
Group:Seismological Laboratory, Division of Geological and Planetary Sciences
Funding AgencyGrant Number
Caltech Division of Geological and Planetary SciencesUNSPECIFIED
ETH ZurichFEL-19 20-2
Record Number:CaltechAUTHORS:20220214-282309900
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:113434
Deposited By: Tony Diaz
Deposited On:14 Feb 2022 19:14
Last Modified:13 Jan 2023 18:08

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