Large‐scale subsidence due to aquifer‐overdraft is an ongoing hazard in the San Joaquin Valley. Subsidence continues to cause damage to infrastructure and increases the risk of extensional fissures.Here, we use InSAR‐derived vertical land motion (VLM) to model the volumetric strain rate due to groundwater storage change during the 2007–2010 drought in the San Joaquin Valley, Central Valley, California. We then use this volumetric strain rate model to calculate surface tensile stress in order to predict regions that are at the highest risk for hazardous tensile surface fissures. We find a maximum volumetric strain rate of −232 microstrain/yr at a depth of 0 to 200 m in Tulare and Kings County, California. The highest risk of tensile fissure development occurs at the periphery of the largest subsiding zones, particularly in Tulare County and Merced County. Finally, we assume that subsidence is likely due to aquifer pressure change, which is calculated using groundwater level changes observed at 300 wells during this drought. We combine pressure data from selected wells with our volumetric strain maps to estimate the quasi‐static bulk modulus, K, a poroelastic parameter applicable when pressure change within the aquifer is inducing volumetric strain. This parameter is reflective of a slow deformation process and is one to two orders of magnitude lower than typical values for the bulk modulus found using seismic velocity data. The results of this study highlight the importance of large‐scale, high‐resolution VLM measurements in evaluating aquifer system dynamics, hazards associated with overdraft, and in estimating important poroelastic parameters.

中文翻译：

---

用于绘制加利福尼亚州圣华金河谷伸展裂缝和约束岩石力学特性的沉降体积应变模型


含水层透支导致的大规模沉降是圣华金河谷持续存在的危险。沉降继续对基础设施造成损害，并增加了伸展裂缝的风险。在这里，我们使用 InSAR 衍生的垂直地面运动 (VLM) 来模拟圣华金河谷 2007 年至 2010 年干旱期间地下水储存变化引起的体积应变率，加利福尼亚州中央谷。然后，我们使用该体积应变率模型来计算表面拉伸应力，以预测危险拉伸表面裂缝风险最高的区域。我们发现加利福尼亚州图莱里和金斯县 0 至 200 m 深度处的最大体积应变率为 -232 微应变/年。张性裂缝发展的最高风险发生在最大沉降区的外围，特别是在图莱里县和默塞德县。最后，我们假设沉降可能是由于含水层压力变化造成的，含水层压力变化是根据这次干旱期间在 300 口井观测到的地下水位变化计算得出的。我们将选定井的压力数据与体积应变图相结合，以估计准静态体积模量K ，这是当含水层内的压力变化引起体积应变时适用的孔隙弹性参数。该参数反映了缓慢的变形过程，并且比使用地震速度数据发现的体积模量的典型值低一到两个数量级。这项研究的结果强调了大规模、高分辨率 VLM 测量在评估含水层系统动态、与透支相关的危险以及估计重要的孔隙弹性参数方面的重要性。