Forearc faults in northern Cascadia do not accommodate elastic strain driven by the megathrust seismic cycle

N. Harrichhausen, K. Morell, C. Regalla
{"title":"Forearc faults in northern Cascadia do not accommodate elastic strain driven by the megathrust seismic cycle","authors":"N. Harrichhausen, K. Morell, C. Regalla","doi":"10.26443/seismica.v2i4.1177","DOIUrl":null,"url":null,"abstract":"We employ numerical models to explore the connection between subduction zone coupling or megathrust rupture and upper plate faults in the northern Cascadia forearc. Active forearc faults north of the Olympic Peninsula exhibit similar characteristics: west-northwest strike, oblique right-lateral slip senses, and low slip rates (<1 mm/yr), but a potential to generate large (M ~ 7) earthquakes. Previous hypotheses suggest that stress in the upper plate due to interseismic coupling or coseismic rupture along the subduction zone interface could drive permanent forearc strain. To test these hypotheses, we used a 3D boundary element method model to predict slip on the LRDM if interseismic coupling or coeseismic rupture cause deformation. Our model predicts reverse left-lateral slip if the strain results solely from subduction zone coupling, or normal right-lateral slip if these faults accommodate strain during a megathrust rupture. These results contradict the observed fault kinematics. Additionally, if we use our model to mimic strain partitioning, where only the strain from the strike-slip component of subduction zone coupling is accommodated in the forearc, our results are also inconsistent observed fault kinematics. These models challenge the hypothesis that subduction zone coupling or coseismic rupture are the primary driver of permanent forearc deformation in northern Cascadia.","PeriodicalId":509514,"journal":{"name":"Seismica","volume":"63 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Seismica","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.26443/seismica.v2i4.1177","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

We employ numerical models to explore the connection between subduction zone coupling or megathrust rupture and upper plate faults in the northern Cascadia forearc. Active forearc faults north of the Olympic Peninsula exhibit similar characteristics: west-northwest strike, oblique right-lateral slip senses, and low slip rates (<1 mm/yr), but a potential to generate large (M ~ 7) earthquakes. Previous hypotheses suggest that stress in the upper plate due to interseismic coupling or coseismic rupture along the subduction zone interface could drive permanent forearc strain. To test these hypotheses, we used a 3D boundary element method model to predict slip on the LRDM if interseismic coupling or coeseismic rupture cause deformation. Our model predicts reverse left-lateral slip if the strain results solely from subduction zone coupling, or normal right-lateral slip if these faults accommodate strain during a megathrust rupture. These results contradict the observed fault kinematics. Additionally, if we use our model to mimic strain partitioning, where only the strain from the strike-slip component of subduction zone coupling is accommodated in the forearc, our results are also inconsistent observed fault kinematics. These models challenge the hypothesis that subduction zone coupling or coseismic rupture are the primary driver of permanent forearc deformation in northern Cascadia.
卡斯卡迪亚北部的弧前断层无法适应大地壳地震周期驱动的弹性应变
我们采用数值模型来探索俯冲带耦合或大断裂与卡斯卡迪亚前弧北部上板块断层之间的联系。奥林匹克半岛以北的活跃弧前断层表现出相似的特征:西-西北走向、斜右侧滑动感应、低滑动率(<1 毫米/年),但有可能产生大地震(M ~ 7)。之前的假设表明,地震间耦合或沿俯冲带界面的共震断裂导致的上板块应力可能会驱动弧前永久应变。为了验证这些假设,我们使用三维边界元法模型预测了地震间耦合或同震破裂引起变形时 LRDM 的滑移。如果应变完全来自俯冲带耦合,我们的模型预测会出现反向左侧滑移;如果这些断层在大地壳破裂过程中产生应变,则会出现正向右侧滑移。这些结果与观测到的断层运动学结果相矛盾。此外,如果用我们的模型模拟应变分区,即前弧(forearc)只容纳俯冲带耦合的走向滑动部分产生的应变,我们的结果也与观测到的断层运动学不一致。这些模型挑战了俯冲带耦合或同震断裂是卡斯卡迪亚北部前弧永久变形的主要驱动力这一假说。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
求助全文
约1分钟内获得全文 求助全文
来源期刊
自引率
0.00%
发文量
0
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
确定
请完成安全验证×
copy
已复制链接
快去分享给好友吧!
我知道了
右上角分享
点击右上角分享
0
联系我们:info@booksci.cn Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。 Copyright © 2023 布克学术 All rights reserved.
京ICP备2023020795号-1
ghs 京公网安备 11010802042870号
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术官方微信