A Unified Model of Crustal Stress Heterogeneity From Borehole Breakouts and Earthquake Focal Mechanisms

Abstract

• We compare SHmax estimates derived from boreholes and from inversion of earthquake focal mechanisms to infer crustal stress heterogeneity • Stress orientation varies with depth within sediment basins, but approaches more homogeneous basement orientations at bedrock interface • Lateral stress orientation heterogeneity is mostly associated with basin margins and proximity to active faults at length scales of 1-20 km

Global Frictional Equilibrium via Stochastic, Local Coulomb Frictional Slips

“…Compilation of local in situ stress data worldwide (e.g., Heidbach et al., 2018; M. L. Zoback, 1992) reveals relatively consistent global stress trend at the regional scale, although with some outliners. The uniformity of the global stress field above certain scales has also been corroborated by earthquake focal mechanism inversions (e.g., Hardebeck, 2010; Iio et al., 2017; Luttrell & Hardebeck, 2021). Generally, we contend that while the heterogeneity of local stress and strength is ubiquitous, the global stress field in most cases can be seen as relatively uniform, albeit with some uncertainty.…”

Tectonic inheritance during plate boundary evolution in southern California constrained from seismic anisotropy

“…Comparison of local shear wave splitting with stress inferences from boreholes indicates that complexities are expected, for example because of shallow fabric rather than crack-stress control (Boness & Zoback, 2006). There are other, more direct indicators of crustal stress from boreholes, but those are not available widely enough, nor are they sampling on the appropriate scales for our study (Luttrell & Hardebeck, 2021;Persaud et al, 2020).…”

Tectonic Inheritance During Plate Boundary Evolution in Southern California Constrained From Seismic Anisotropy

“…Comparison of local shear wave splitting with stress inferences from boreholes indicates that complexities are expected, for example because of shallow fabric rather than crack‐stress control (Boness & Zoback, 2006). There are other, more direct indicators of crustal stress from boreholes, but those are not available widely enough, nor are they sampling on the appropriate scales for our study (Luttrell & Hardebeck, 2021; Persaud et al., 2020).…”