Widespread inelastic deformation from integrated fracture, aftershock, and strain maps of the 2019 Ridgecrest earthquakes

Michael E. Oskin, Chris Milliner, & Andreas Plesch

In Preparation April 28, 2021, SCEC Contribution #10995

A ubiquitous model for the crust is rigid blocks delimited by faults that accommodate the long-term tectonic rate and are surrounded by narrow zones of deformation (100m-1km). Here we show, using a combination of high-resolution fracture, strain, and aftershock maps from the 2019 Ridgecrest earthquakes, that inelastic deformation is widespread, extending up to ~25km away from the fault. The decay of fracture density, aftershock density, and strain intensity with distance away from the fault is well described by an inverse power law with exponent ~1.2 and is insensitive to lithology and rupture directivity, suggesting these deformation processes are the product of the same stress field and mechanism. By comparing the spatial extent and style of these datasets, we find that the extent of damage zones may be traditionally mischaracterized due to data resolution bias and that damage zones are continuous features without breaks in scaling. Our results challenge the use of rigid block models and suggest that the crust may be better described as a widely damaged volume that is permanently deformed by inelastic contributions from each individual earthquake.

Citation
Oskin, M. E., Milliner, C., & Plesch, A. (2021). Widespread inelastic deformation from integrated fracture, aftershock, and strain maps of the 2019 Ridgecrest earthquakes. Nature Geoscience, (in preparation).