Data From: The Earthquake Arrest Zone
Ke, Chun-Yu; McLaskey, Gregory C.; Kammer, David S.
These data are from Laboratory Earthquake Experiments from the Cornell 3 m apparatus in support of the following research: Loading a 3-meter granite slab containing a saw-cut simulated fault, we generated slip events that spontaneously nucleate, propagate, and arrest before reaching the ends of the sample. These rupture events have a slip distribution that varies along the fault and make them more similar to natural earthquakes than standard stick-slip events that rupture the entire sample. We propose an analytical crack model that fits our measurements. Similar to natural earthquakes, laboratory measurements show coseismic slip that gradually tapers near the rupture tips. Measured stress changes show roughly constant stress drop in the center of the ruptured region, a maximum stress increase near the rupture tips, and a smooth transition in between, in a region we describe as the earthquake arrest zone. The proposed model generalizes the widely used elliptical crack model by adding gradually tapered slip at the ends of the rupture. Different from the cohesive zone described by fracture mechanics, we propose that the transition in stress changes and the corresponding linear taper observed in the earthquake arrest zone are the result of rupture termination conditions primarily controlled by the initial stress distribution. It is the heterogeneous initial stress distribution that controls the arrest of laboratory earthquakes, and the features of static stress changes. We also performed dynamic rupture simulations that confirm how arrest conditions can affect slip taper and static stress changes. If applicable to larger natural earthquakes, this distinction between an earthquake arrest zone (that depends on stress conditions) and a cohesive zone (that depends primarily on strength evolution) has important implications for how seismic observations of earthquake fracture energy should be interpreted.
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This work was sponsored by USGS Earthquake hazards grant G18AP00010 and National Science Foundation grants EAR-1645163, EAR-1763499, and EAR-1847139.
analytical crack model; crack tip; earthquake termination
Chun-Yu Ke, Gregory C McLaskey, David S Kammer, The earthquake arrest zone, Geophysical Journal International, Volume 224, Issue 1, January 2021, Pages 581–589. https://doi.org/10.1093/gji/ggaa386
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