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Published May 16, 2022 | Submitted + Published + Accepted Version + Supplemental Material
Journal Article Open

Aftershock Moment Tensor Scattering


Coseismic rotations of principal stress axes can provide insights into the strength of the crust, but it is unclear how common this phenomenon is. We use a nearest-neighbor clustering algorithm to identify earthquake sequences in the global ISC-GEM catalog and the regional Southern California catalog. Using an inner-product-based pairwise measure of moment tensor similarity, we demonstrate that, in both catalogs, aftershocks are less similar to their respective mainshocks than foreshocks are. We interpret this effect, which we call moment tensor scattering, as evidence for widespread coseismic stress rotations. Moment tensor scattering is observable for a broad range of mainshock magnitudes in both catalogs. We further demonstrate that mainshock-aftershock similarity recovers logarithmically to pre-mainshock levels on decadal timescales. We conclude that moment tensor scattering is a generally observable feature of seismic sequences which may be useful in future work to discriminate between models of crustal strength.

Additional Information

© 2022 American Geophysical Union. Issue Online: 29 April 2022; Version of Record online: 29 April 2022; Accepted manuscript online: 26 April 2022; Manuscript accepted: 21 April 2022; Manuscript revised: 17 April 2022; Manuscript received: 24 February 2022. The authors thank three anonymous reviewers for thoughtful comments which contributed to the clarity of the manuscript. Data Availability Statement: The ISC-GEM catalog (Bondár et al., 2015; Di Giacomo et al., 2018; D. A. Storchak et al., 2013; D. Storchak et al., 2015) is available for download at http://www.isc.ac.uk/iscgem/. GCMT solutions (Dziewonski et al., 1981; Ekström et al., 2012) are available for download at https://globalcmt.org. Southern California data products are from the Southern California Seismic Network and Southern California Earthquake Data Center (doi:10.7909/C3WD3xH1). The waveform cross-correlation relocated SCSN catalog (Hauksson et al., 2012; Lin et al., 2007) and focal mechanism data for this catalog (Yang et al., 2012) are available for download at https://scedc.caltech.edu/data/downloads.html.

Attached Files

Published - 2022GL098473.pdf

Accepted Version - 2022GL098473-acc.pdf

Submitted - essoar10510672.1.pdf

Supplemental Material - 2022gl098473-sup-0001-supportinginformationsi-s01.pdf


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