Inelastic deformation accrued over multiple seismic cycles: Insights from an elastic-plastic slider-and-springboard model

Autor: Pierre Dublanchet, Jean-Arthur Olive
Jazyk: angličtina
Rok vydání: 2024
Předmět:
Zdroj: Seismica, Vol 3, Iss 2 (2024)
Druh dokumentu: article
ISSN: 2816-9387
DOI: 10.26443/seismica.v3i2.1345
Popis: We study a toy model designed to build physical insight into the problem of slow accumulation of non-recoverable strain in fault blocks over multiple earthquake cycles. The model consists of a thin, horizontal elastic-plastic plate (springboard) in frictional contact with a vertical, rigid wall moving downward at a steady speed. Our model produces stick-slip cycles consisting of interseismic plate downwarping and coseismic plate upwarping as long as the moment of the frictional force at the contact does not exceed the maximum (purely plastic) bending moment the plate can sustain. We show that the duration of individual earthquake cycles and the spatial pattern of interseismic deflection are controlled by two stress ratios involving the peak yield stress of the plate, the frictional strength of the fault and the coseismic stress drop. We show that non-recoverable plate deflection accumulates over successive earthquake cycles if the plate’s yield strength decreases through time, causing a progressive decrease of the aforementioned stress ratios. We derive scaling relations between the rate of accumulation of inelastic deformation, the relative tectonic plate velocity, and the rate of lithospheric weakening. Our results are consistent with observations of long-term permanent deformation of natural fault regions.
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