TY - JOUR
T1 - Surface faulting earthquake clustering controlled by fault and shear-zone interactions
AU - Mildon, Zoë K.
AU - Roberts, Gerald P.
AU - Faure, Walker JP
AU - Beck, Joakim
AU - Papanikolaou, Ioannis
AU - Michetti, Alessandro M.
AU - Toda, Shinji
AU - Iezzi, Francesco
AU - Campbell, Lucy
AU - McCaffrey, Kenneth J.W.
AU - Shanks, Richard
AU - Sgambato, Claudia
AU - Robertson, Jennifer
AU - Meschis, Marco
AU - Vittori, Eutizio
PY - 2022/11/21
Y1 - 2022/11/21
N2 - 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 36Cl 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.
AB - 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 36Cl 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.
U2 - 10.1038/s41467-022-34821-5
DO - 10.1038/s41467-022-34821-5
M3 - Article
SN - 2041-1723
VL - 13
JO - Nature Communications
JF - Nature Communications
IS - 1
ER -
