I employ an elasticity-based method to invert a geodetically derived surface velocity field in the western US using for present-day surface strain rate fields with uncertainties. The method uses distributed body forces in a thin elastic sheet and allows for discontinuities in velocity across creeping faults using the solution for dislocations in a thin elastic plate. I compare the strain rate fields with previously published stress orientations and moment rates from geological slip rate data and previous geodetic studies. Geologic and geodetic moment rates are calculated using slip rate and off-fault strain rates from the 2023 US National Seismic Hazard Model (NSHM) deformation models. I find that computed total geodetic moment rates are higher than NSHM summed moment rates on faults for all regions of the western US except the highest deforming rate regions including the Western Transverse Ranges and the northern and southern San Andreas Fault (SAF) system in California. Computed geodetic moment rates are comparable to the moment rates derived from the geodetically based NSHM deformation models in all regions. I find systematic differences in orientations of maximum horizontal shortening rate and maximum horizontal compressive stress in the Pacific Northwest region and along much of the SAF system. In the Pacific Northwest, the maximum horizontal stress orientations are rotated counterclockwise 40–90° relative to the maximum horizontal strain rate directions. Along the SAF system, the maximum horizontal stresses are rotated systematically 25–40° clockwise (closer to fault normal) relative to the strain rates.

中文翻译：

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美国西部大地测量推断的应变率与应力方向和地质矩率的不一致

我采用基于弹性的方法来反演美国西部大地测量得出的表面速度场，用于当今具有不确定性的表面应变率场。该方法使用薄弹性片中的分布体力，并使用薄弹性板中位错的解来允许跨越蠕变断层的速度不连续性。我将应变率场与之前发布的地质滑移率数据和之前的大地测量研究中的应力方向和力矩率进行了比较。地质和大地矩率是使用 2023 年美国国家地震灾害模型 (NSHM) 变形模型中的滑移率和断层应变率计算的。我发现，计算出的总大地矩速率高于美国西部所有地区断层上的 NSHM 矩速率总和，除了变形速率最高的区域，包括西部横断山脉和加利福尼亚州北部和南部的圣安德烈亚斯断层 (SAF) 系统。计算出的大地矩速率与所有区域中基于大地测量的 NSHM 变形模型得出的矩速率相当。我发现太平洋西北地区和大部分 SAF 系统的最大水平缩短率和最大水平压应力的方向存在系统差异。在太平洋西北地区，最大水平应力方向相对于最大水平应变率方向逆时针旋转 40-90°。沿着 SAF 系统，最大水平应力相对于应变率系统地顺时针旋转 25-40°（更接近断层法向）。