{"title":"Unsteady slip pulses under spatially-varying prestress","authors":"Anna Pomyalov, Eran Bouchbinder","doi":"arxiv-2407.21539","DOIUrl":null,"url":null,"abstract":"It was recently established that self-healing slip pulses under uniform\nprestress $\\tau_b$ are unstable frictional rupture modes, i.e., they either\nslowly expand/decay with time t. Furthermore, their dynamics were shown to\nfollow a reduced-dimensionality description corresponding to a special $L(c)$\nline in a plane defined by the pulse propagation velocity $c(t)$ and size\n$L(t)$. Yet, uniform prestress is rather the exception than the rule in natural\nfaults. We study the effects of a spatially-varying prestress $\\tau_b(x)$ on 2D\nslip pulses, initially generated under a uniform $\\tau_b$ along a\nrate-and-state friction fault. We consider periodic and constant-gradient\nprestress $\\tau_b(x)$ around the reference uniform $\\tau_b$. For a periodic\n$\\tau_b(x)$, pulses either sustain and form quasi-limit cycles in the $L-c$\nplane or decay predominantly monotonically along the $L(c)$ line, depending on\nthe instability index of the initial pulse and the properties of the periodic\n$\\tau_b(x)$. For a constant-gradient $\\tau_b(x)$, expanding/decaying pulses\nclosely follow the $L(c)$ line, with systematic shifts determined by the sign\nand magnitude of the gradient. We also find that a spatially-varying\n$\\tau_b(x)$ can revert the expanding/decaying nature of the initial reference\npulse. Finally, we show that a constant-gradient $\\tau_b(x)$, of sufficient\nmagnitude and specific sign, can lead to the nucleation of a back-propagating\nrupture at the healing tail of the initial pulse, generating a bilateral\ncrack-like rupture. This pulse-to-crack transition, along with the\nabove-described effects, demonstrate that rich rupture dynamics merge from a\nsimple, nonuniform prestress. Furthermore, we show that as long as pulses\nexist, their dynamics are related to the special $L(c)$ line, providing an\neffective, reduced-dimensionality description of unsteady slip pulses under\nspatially-varying prestress.","PeriodicalId":501270,"journal":{"name":"arXiv - PHYS - Geophysics","volume":"34 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"arXiv - PHYS - Geophysics","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/arxiv-2407.21539","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
It was recently established that self-healing slip pulses under uniform
prestress $\tau_b$ are unstable frictional rupture modes, i.e., they either
slowly expand/decay with time t. Furthermore, their dynamics were shown to
follow a reduced-dimensionality description corresponding to a special $L(c)$
line in a plane defined by the pulse propagation velocity $c(t)$ and size
$L(t)$. Yet, uniform prestress is rather the exception than the rule in natural
faults. We study the effects of a spatially-varying prestress $\tau_b(x)$ on 2D
slip pulses, initially generated under a uniform $\tau_b$ along a
rate-and-state friction fault. We consider periodic and constant-gradient
prestress $\tau_b(x)$ around the reference uniform $\tau_b$. For a periodic
$\tau_b(x)$, pulses either sustain and form quasi-limit cycles in the $L-c$
plane or decay predominantly monotonically along the $L(c)$ line, depending on
the instability index of the initial pulse and the properties of the periodic
$\tau_b(x)$. For a constant-gradient $\tau_b(x)$, expanding/decaying pulses
closely follow the $L(c)$ line, with systematic shifts determined by the sign
and magnitude of the gradient. We also find that a spatially-varying
$\tau_b(x)$ can revert the expanding/decaying nature of the initial reference
pulse. Finally, we show that a constant-gradient $\tau_b(x)$, of sufficient
magnitude and specific sign, can lead to the nucleation of a back-propagating
rupture at the healing tail of the initial pulse, generating a bilateral
crack-like rupture. This pulse-to-crack transition, along with the
above-described effects, demonstrate that rich rupture dynamics merge from a
simple, nonuniform prestress. Furthermore, we show that as long as pulses
exist, their dynamics are related to the special $L(c)$ line, providing an
effective, reduced-dimensionality description of unsteady slip pulses under
spatially-varying prestress.