Paleostress and Mechanisms of Slip on the San Gabriel Fault,San Andreas Fault System, California

来自浅井的主应力方向数据表明，加利福尼亚州圣安德烈亚斯断层上存在低震级剪应力。这些数据与热流测量和预测是一致的，但与岩石的估计强度不一致。这个项目将试图通过确定圣加布里埃尔断裂活动期间存在的主应力的方向来检验浅井资料代表中地壳深处的应力状态这一假设。通过对断裂带内构造的岩组分析，确定古应力方向和滑动机制。将结果与实验室数据进行比较，并将其应用于断层强度明显较弱的问题。

Data on principal stress orientation from shallow wells indicate a low magnitude shear stress on the San Andreas Fault, California. These data are consistent with heat-flow measure- ments and predictions, but are inconsistent with estimated strength of rocks. This project will attempt to test the hypo- thesis that the shallow well data are representative of the state of stress at mid-crustal depths by determining the orien- tation of the principal stresses that existed during activity on the San Gabriel fault, now deeply exhumed. Paleostress orien- tations and mechanisms of slip will be determined by petrofabric analysis of structures in the fault zone. Results will be compared to laboratory data and applied to the problem of the apparently weak fault strength.