Collaborative Research (USC/UCLA/UCR/SDSU): Continuing Study of Internal Structure, Dynamic Rupture and Post-Earthquake Healing of the Hector Mine Rupture Zone

提案标题：合作研究（南加州大学/加州大学洛杉矶分校/加州大学河滨分校）：赫克托煤矿断裂带内部结构、断裂和地震后愈合的持续研究。NSF提案编号：0229324，0229452，0229678主要研究者：李永刚，约翰E。Vidale和大卫D.我们建议继续我们的研究地震后愈合，断层带过程，和动态破裂的1999年7. 1赫克托矿，加州，地震使用断层带捕获波。余震和爆炸产生的断层带捕获波的观测和FD模拟，并记录在部署在赫克托煤矿地表破裂的线性地震台阵，揭示了一个~100米宽的低速波导沿着破裂带，和北方破裂在孕震深度的分叉。 我们以前的工作也表明，这个低速波导已经愈合，因为主震，P和S波速度增加了约1%之间的2000年和2001年。继续监测赫克托矿破裂区的愈合情况将有助于我们了解其愈合速度是否会随着时间的推移而减慢，就像兰德斯的愈合速度一样。在本研究中，我们将1）重复2003年的实验，进一步寻找断层愈合的时间和空间依赖性的证据; 2）建立一个基于裂缝非线性理论和化学封闭的力学模型，用于解释断层愈合; 3）模拟多个断层段的动态破裂，并将这些模型与断层带岩体的损伤程度联系起来; 4）分析剪切波分裂，研究近断层应力状态及其随时间的变化; 5）比较Hector矿和Landers矿的断层愈合情况，了解平行断层系统中断层的相互作用。通过本项目，我们将更好地了解断裂带内部结构、破裂过程和地震周期之间的关系。了解断层结构的时空变化将有助于解决断层强度变化和断层段及断层网络的动态响应的更现实的宏观表示，以及预测未来地震的行为。

Proposal Title: Collaborative Research (USC/UCLA/UCR): Continuing Study of Internal Structure, Rupture, and Post-Earthquake Healing of the Hector Mine Rupture Zone.NSF Proposal Number: EAR-0229324, 0229452, 0229678Principal Investigators: Yong-Gang Li, John E. Vidale, and David D. OglesbyABSTRACT We propose to continue our study of post-earthquake healing, fault zone process, and dynamic rupture of the 1999 M7.1 Hector Mine, California, earthquake using fault-zone trapped waves. Observations and FD simulations of fault-zone trapped waves generated by aftershocks and explosions, and recorded at linear seismic arrays deployed across the Hector Mine surface rupture, have revealed a ~100 m wide low-velocity waveguide along the rupture zone, and the bifurcation of northern rupture at the seismogenic depth. Our previous work has also shown that this low-velocity waveguide has healed since the mainshock, with P and S wave velocities increasing by ~1% between 2000 and 2001. Continued monitoring of healing in the Hector Mine rupture zone will help us to see if its healing rate slows with time, as did the healing rate at Landers. In the present proposal, we shall 1) repeat the experiment in 2003 to find further evidence of the time- and spatial-dependence of fault healing; 2) develop a mechanical model based on crack dilatancy theory combined with chemical sealing for interpretation of fault healing; 3) simulate dynamic rupture on multiple fault segments and relate these models to the extent of damage to the rock mass in fault zone; 4) analyze shear-wave splitting for study of the near-fault stress state and its temporal variation; 5) compare the fault healing at Hector Mine with that at Landers for understanding the fault interaction in a parallel-fault system. Through this project, we will obtain a better understanding for the relationships between the fault zone internal structure, rupture process, and earthquake cycle. Knowledge of spatial and temporal variations in the fault structure will help resolve more realistic macroscopic representations of fault-strength variations and the dynamic response of fault segments and fault networks as well as predict behavior of future earthquake.