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Title: Earthquake Sequence Dynamics at the Interface Between an Elastic Layer and Underlying Half‐Space in Antiplane Shear

We quantify sliding stability and rupture styles for a horizontal interface between an elastic layer and stiffer elastic half‐space with a free surface on top and rate‐and‐state friction on the interface. This geometry includes shallowly dipping subduction zones, landslides, and ice streams. Specific motivation comes from quasiperiodic slow slip events on the Whillans Ice Plain in West Antarctica. We quantify the influence of layer thickness on sliding stability, specifically whether a steadily loaded system produces steady sliding or stick‐slip sequences. We do this using both linear stability analysis and nonlinear earthquake sequence simulations. We restrict our attention to the 2‐D antiplane shear problem but anticipate that our findings generalize to more complex 2‐D in‐plane and 3‐D problems. Steady sliding with velocity‐weakening rate‐and‐state friction is linearly unstable to Fourier mode perturbations having wavelengths greater than a critical wavelength (λc). We quantify the dependence ofλcon the rate‐and‐state friction parameters, elastic properties, loading, and the layer thickness (H). Confirming previous studies, we find thatλc ∝ H1/2for smallHand is independent ofHfor largeH. The linear stability analysis provides insight into nonlinear earthquake sequence dynamics of a nominally velocity‐strengthening interface containing a velocity‐weakening region of widthW. Sequence simulations reveal a transition from steady sliding at smallWto stick‐slip events whenWexceeds a critical width (Wcr), withWcr ∝ H1/2for smallH. Overall, this study demonstrates that the reduced stiffness of thin layers promotes instability, with implications for sliding dynamics in thin layer geometries.

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Author(s) / Creator(s):
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Publisher / Repository:
DOI PREFIX: 10.1029
Date Published:
Journal Name:
Journal of Geophysical Research: Solid Earth
Medium: X
Sponsoring Org:
National Science Foundation
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