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Interseismic Coupling and Slow Slip Events on the Cascadia Megathrust

Michel, Sylvain and Gualandi, Adriano and Avouac, Jean-Philippe (2019) Interseismic Coupling and Slow Slip Events on the Cascadia Megathrust. Pure and Applied Geophysics, 176 (9). pp. 3867-3891. ISSN 0033-4553. https://resolver.caltech.edu/CaltechAUTHORS:20180924-160011784

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Abstract

In this study, we model geodetic strain accumulation along the Cascadia subduction zone between 2007.0 and 2017.632 using position time series from 352 continuous GPS stations. First, we use the secular linear motion to determine interseismic locking along the megathrust. We determine two end member models, assuming that the megathrust is either a priori locked or creeping, which differ essentially along the trench where the inversion is poorly constrained by the data. In either case, significant locking of the megathrust updip of the coastline is needed. The downdip limit of the locked portion lies ∼ 20–80 km updip from the coast assuming a locked a priori, but very close to the coast for a creeping a priori. Second, we use a variational Bayesian Independent Component Analysis (vbICA) decomposition to model geodetic strain time variations, an approach which is effective to separate the geodetic strain signal due to non-tectonic and tectonic sources. The Slow Slip Events (SSEs) kinematics is retrieved by linearly inverting for slip on the megathrust the Independent Components related to these transient phenomena. The procedure allows the detection and modelling of 64 SSEs which spatially and temporally match with the tremors activity. SEEs and tremors occur well inland from the coastline and follow closely the estimated location of the mantle wedge corner. The transition zone, between the locked portion of the megathrust and the zone of tremors, is creeping rather steadily at the long-term slip rate and probably buffers the effect of SSEs on the megathrust seismogenic portion.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1007/s00024-018-1991-xDOIArticle
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https://doi.org/10.1007/s00024-018-2006-7DOICorrection
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ORCID:
AuthorORCID
Michel, Sylvain0000-0001-7878-6603
Gualandi, Adriano0000-0002-3100-8932
Avouac, Jean-Philippe0000-0002-3060-8442
Additional Information:© The Author(s) 2018. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Received: 10 June 2018; Revised: 27 August 2018; Accepted: 06 September 2018; First Online: 24 September 2018. We thank Kelin Wang for his constructive review of this manuscript. This study was partially supported by NSF award EAR-1821853 to JPA. We thank also Zachary E. Ross for his help. We thank Kristel Chanard for discussions and providing the times series predicted based on the surface mass variations derived from GRACE.
Errata:Owing to an unfortunate oversight, the wrong figure 2 has been published. Unfortunately also the acknowledgement has been omitted. Acknowledgements: We thank Kelin Wang for his constructive review of this manuscript. This study was partially supported by NSF award EAR-1821853 to JPA. We thank also Zachary E. Ross for his help. We thank Richard Walters and David Al-Attar for their detailed and constructive criticism which helped improve our study.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
NSFEAR-1821853
Subject Keywords:Cascadia megathrust, slow slip events, interseismic coupling, variational bayesian independent component analysis
Issue or Number:9
Record Number:CaltechAUTHORS:20180924-160011784
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20180924-160011784
Official Citation:Michel, S., Gualandi, A. & Avouac, JP. Pure Appl. Geophys. (2019) 176: 3867. https://doi.org/10.1007/s00024-018-1991-x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:89897
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:24 Sep 2018 23:08
Last Modified:03 Oct 2019 20:20

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