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Inverse Migration of Seismicity Quiescence During the 2019 Ridgecrest Sequence

Marsan, D. and Ross, Z. E. (2021) Inverse Migration of Seismicity Quiescence During the 2019 Ridgecrest Sequence. Journal of Geophysical Research. Solid Earth, 126 (3). Art. No. e2020JB020329. ISSN 2169-9313. doi:10.1029/2020jb020329.

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Seismicity quiescences are best observed during sequences with multiple mainshocks and often emerge with some delay after an initial phase of aftershock triggering. The mechanisms controlling this delay are poorly understood, due to a lack of systematic and precise estimation of the duration of the triggering phase which is made complicated by the rapidly changing magnitude of completeness after the mainshock. Here, we analyze how such a delayed quiescence developed during the 2019 Ridgecrest (California) sequence, using a refined earthquake data set obtained by template matching and relative relocation. A method that allows estimating the aftershock occurrence rate after correcting for the change in detection (completeness magnitude) is applied. We find that an immediate seismicity shutdown was triggered by the second (M7.1) mainshock at the tips of the north‐east trending cross‐cut fault that hosted most of the slip of the first (M6.4) mainshock. This shutdown progressed toward the central part of this fault over the following days. The overall shutdown of the aftershock sequence of the M6.4 by the M7.1 rupture is consistent with static Coulomb stress modeling. This inverse migration is a unique observation, best explained by an enhanced spatial stress change variability in this central part where the cross‐cut fault intersects the main fault of the M7.1 shock, hence a strongly damaged zone there. This further confirms previous observations of an enhanced structural disorder in this central part of the cross fault, showing that structural disorder has a first‐order control on the seismicity dynamics at the scale of days.

Item Type:Article
Related URLs:
URLURL TypeDescription ItemQTM dataset ItemSCSN earthquake catalog ItemM7.1 slip model of Ross et al.
Marsan, D.0000-0002-1084-8465
Ross, Z. E.0000-0002-6343-8400
Additional Information:© 2021 American Geophysical Union. Issue Online: 10 March 2021; Version of Record online: 10 March 2021; Accepted manuscript online: 03 February 2021; Manuscript accepted: 16 October 2020; Manuscript revised: 25 September 2020; Manuscript received: 02 June 2020. This work was funded by the Agence Nationale de la Recherche (ANR‐17‐CE31‐0002‐01) AtypicSSE project. The authors thank Yen Joe Tan, Ross Stein, James Hollingsworth for discussions on this work, as well as the Associate Editor and the two anonymous reviewers who helped us improving this manuscript. Data Availability Statement: The QTM data set can be found at The SCSN earthquake catalog is at The authors used the M7.1 slip model of Ross et al. (2019) which can be accessed at the SRCMOD database We used the Coulomb 3.4 software of Toda et al. (2011).
Group:Seismological Laboratory
Funding AgencyGrant Number
Agence Nationale pour la Recherche (ANR)ANR‐17‐CE31‐0002‐01
Issue or Number:3
Record Number:CaltechAUTHORS:20210208-125848126
Persistent URL:
Official Citation:Marsan, D., & Ross, Z. E. (2021). Inverse migration of seismicity quiescence during the 2019 Ridgecrest sequence. Journal of Geophysical Research: Solid Earth, 126, e2020JB020329.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107952
Deposited By: Tony Diaz
Deposited On:08 Feb 2021 21:12
Last Modified:16 Nov 2021 19:07

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