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Dynamics and Near-Field Surface Motions of Transitioned Supershear Laboratory Earthquakes in Thrust Faults

Tal, Yuval and Rubino, Vito and Rosakis, Ares J. and Lapusta, Nadia (2022) Dynamics and Near-Field Surface Motions of Transitioned Supershear Laboratory Earthquakes in Thrust Faults. Journal of Geophysical Research. Solid Earth, 127 (3). Art. No. e2021JB023733. ISSN 2169-9313. doi:10.1029/2021jb023733. https://resolver.caltech.edu/CaltechAUTHORS:20220317-377260000

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Abstract

We study how the asymmetric geometry of thrust faults affects the dynamics of supershear ruptures and their associated trailing Rayleigh ruptures as they interact with the free surface, and investigate the resulting near-field ground motions. Earthquakes are mimicked by propagating laboratory ruptures along a frictional interface with a 61° dip angle. Using an experimental technique that combines ultrahigh-speed photography with digital image correlation, we produce sequences of full-field evolving measurements of particle displacements and velocities. Our full-field measurement capability allows us to confirm and quantify the asymmetry between the experimental motions of the hanging and footwalls, with larger velocity magnitudes occurring at the hanging wall. Interestingly, because the motion of the hanging wall is generally near-vertical, while that of the footwall is at dip direction shallower than the dip angle of the fault, the horizontal surface velocity components are found to be larger at the footwall than at the hanging wall. The attenuation in surface velocity with distance from the fault trace is generally larger at the hanging wall than at the footwall and it is more pronounced in the vertical component than in the horizontal one. Measurements of the rotations in surface motions confirm experimentally that the interaction of the rupture with the free surface can be interpreted through a torqueing mechanism that leads to reduction in normal stress near the free surface for thrust earthquakes. Nondimensional analysis shows that the experimental measurements are consistent with larger-scale numerical simulations as well as field observations from thrust earthquakes.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1029/2021JB023733DOIArticle
https://osf.io/nts3eRelated ItemData
ORCID:
AuthorORCID
Tal, Yuval0000-0001-7308-9294
Rubino, Vito0000-0002-4023-8668
Rosakis, Ares J.0000-0003-0559-0794
Lapusta, Nadia0000-0001-6558-0323
Additional Information:© 2022 American Geophysical Union. Issue Online: 23 March 2022; Version of Record online: 23 March 2022; Accepted manuscript online: 15 March 2022; Manuscript accepted: 12 March 2022; Manuscript revised: 10 March 2022; Manuscript received: 29 November 2021. This study was supported by the US National Science Foundation (NSF; EAR-2045285 and EAR-1651235), the US Geological Survey (USGS; grant G16AP00106), the NSF-IUCRC at California Institute of Technology-Center for Geomechanics and Mitigation of Geohazards (GMG), and the Southern California Earthquake Center (SCEC), contribution No. 11815. SCEC is funded by NSF Cooperative Agreement EAR-1600087 and USGS Cooperative Agreement G17AC00047. Data Availability Statement: The experimental data used for this study can be found at https://osf.io/nts3e.
Group:GALCIT
Funders:
Funding AgencyGrant Number
NSFEAR-2045285
NSFEAR-1651235
USGSG16AP00106
Center for Geomechanics and Mitigation of GeohazardsUNSPECIFIED
Southern California Earthquake Center (SCEC)UNSPECIFIED
NSFEAR-1600087
USGSG17AC00047
Subject Keywords:Thrust faults; Dynamic ruptures; Laboratory earthquakes; Ground motion; Digital image correlation; Supershear
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Southern California Earthquake Center (SCEC)11815
Issue or Number:3
DOI:10.1029/2021jb023733
Record Number:CaltechAUTHORS:20220317-377260000
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20220317-377260000
Official Citation:Tal, Y., Rubino, V., Rosakis, A. J., & Lapusta, N. (2022). Dynamics and near-field surface motions of transitioned supershear laboratory earthquakes in thrust faults. Journal of Geophysical Research: Solid Earth, 127, e2021JB023733. https://doi.org/10.1029/2021JB023733
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:113953
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:17 Mar 2022 20:04
Last Modified:19 Apr 2022 17:41

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