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Earthquake nucleation in the lower crust by local stress amplification

Campbell, L. R.; Menegon, L.; Fagereng, Å.; Pennacchioni, G.

Authors

L. R. Campbell

L. Menegon

Å. Fagereng

G. Pennacchioni



Abstract

Deep intracontinental earthquakes are poorly understood, despite their potential to cause significant destruction. Although lower crustal strength is currently a topic of debate, dry lower continental crust may be strong under high-grade conditions. Such strength could enable earthquake slip at high differential stress within a predominantly viscous regime, but requires further documentation in nature. Here, we analyse geological observations of seismic structures in exhumed lower crustal rocks. A granulite facies shear zone network dissects an anorthosite intrusion in Lofoten, northern Norway, and separates relatively undeformed, microcracked blocks of anorthosite. In these blocks, pristine pseudotachylytes decorate fault sets that link adjacent or intersecting shear zones. These fossil seismogenic faults are rarely >15 m in length, yet record single-event displacements of tens of centimetres, a slip/length ratio that implies >1 GPa stress drops. These pseudotachylytes represent direct identification of earthquake nucleation as a transient consequence of ongoing, localised aseismic creep.

Citation

Campbell, L. R., Menegon, L., Fagereng, Å., & Pennacchioni, G. (2020). Earthquake nucleation in the lower crust by local stress amplification. Nature communications, 11(1), Article 1322. https://doi.org/10.1038/s41467-020-15150-x

Journal Article Type Article
Acceptance Date Feb 14, 2020
Online Publication Date Mar 12, 2020
Publication Date 2020-12
Deposit Date Apr 3, 2022
Publicly Available Date Apr 4, 2022
Journal Nature Communications
Publisher Nature Publishing Group
Peer Reviewed Peer Reviewed
Volume 11
Issue 1
Article Number 1322
DOI https://doi.org/10.1038/s41467-020-15150-x
Keywords Geophysics; Seismology; Structural geology; Tectonics
Public URL https://hull-repository.worktribe.com/output/3752761

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Copyright Statement
© The Author(s) 2020.
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as 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. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/ licenses/by/4.0/.






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