Surface faulting earthquake clustering controlled by fault and shear-zone interactions

Surface faulting earthquakes are known to cluster in time from historical and palaeoseismic studies, but the mechanism(s) responsible for clustering, such as fault interaction, strain-storage, and evolving dynamic topography, are poorly quantified, and hence not well understood. We present a quantif...

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Bibliographic Details
Published in:Nature communications 2022-11, Vol.13 (1), p.7126-7126, Article 7126
Main Authors: Mildon, Zoë K., Roberts, Gerald P., Faure Walker, Joanna P., Beck, Joakim, Papanikolaou, Ioannis, Michetti, Alessandro M., Toda, Shinji, Iezzi, Francesco, Campbell, Lucy, McCaffrey, Kenneth J. W., Shanks, Richard, Sgambato, Claudia, Robertson, Jennifer, Meschis, Marco, Vittori, Eutizio
Format: Article
Language:English
Subjects:
704/2151/213/536
704/2151/562
704/4111
Clustering
Earthquakes
Fault lines
Geological faults
Geological hazards
Hazard assessment
Humanities and Social Sciences
multidisciplinary
Science
Science (multidisciplinary)
Seismic activity
Seismic hazard
Shear zone
Slip
Strain rate
Stress
Stress transfer
Viscous flow
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Summary:Surface faulting earthquakes are known to cluster in time from historical and palaeoseismic studies, but the mechanism(s) responsible for clustering, such as fault interaction, strain-storage, and evolving dynamic topography, are poorly quantified, and hence not well understood. We present a quantified replication of observed earthquake clustering in central Italy. Six active normal faults are studied using 36 Cl cosmogenic dating, revealing out-of-phase periods of high or low surface slip-rate on neighboring structures that we interpret as earthquake clusters and anticlusters. Our calculations link stress transfer caused by slip averaged over clusters and anti-clusters on coupled fault/shear-zone structures to viscous flow laws. We show that (1) differential stress fluctuates during fault/shear-zone interactions, and (2) these fluctuations are of sufficient magnitude to produce changes in strain-rate on viscous shear zones that explain slip-rate changes on their overlying brittle faults. These results suggest that fault/shear-zone interactions are a plausible explanation for clustering, opening the path towards process-led seismic hazard assessments. The mechanisms responsible for clustering of surface fault earthquakes are often unclear. Here the authors find that differential stress fluctuates during fault/shear-zone interactions which can produce changes in strain-rate and slip-rate changes leading to earthquake clustering.
ISSN:2041-1723
2041-1723
DOI:10.1038/s41467-022-34821-5