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(USC/UCLA/UCR)：继续研究赫克托矿破裂带的内部结构、破裂和震后修复。美国国家科学基金会提案编号：EAR-0229324,0229452,0229678主要调查人员：李永刚，约翰·E·维代尔和大卫·D·奥格尔斯摘要我们建议继续利用断裂带捕获波对1999年加州赫克托矿7.1级地震的震后愈合、断裂带过程和动态破裂进行研究。对由余震和爆炸产生的断层带陷波的观测和FD模拟，以及部署在赫克托矿地表破裂上的线性地震台阵记录的记录，揭示了沿破裂带约100m宽的低速波导管，以及孕震深度处北向破裂的分叉。我们以前的工作也表明，这种低速波导会在主震后痊愈，2000年至2001年，P波和S波的波速增加了约1%。继续监测赫克托地雷破裂区的愈合情况将有助于我们了解其愈合率是否会随着时间的推移而放缓，就像兰德斯的愈合率一样。在本建议中，我们将1)重复2003年的实验，以寻找断层愈合的时间和空间相关性的进一步证据；2)建立基于裂隙扩张理论和化学封闭相结合的力学模型来解释断层愈合；3)模拟多个断层段的动态破裂，并将这些模型与断层带中岩体的损伤程度相关联；4)分析横波分裂，以研究近断层应力状态及其时间变化；5)比较赫克托矿和兰德斯矿的断层愈合情况，以了解平行断层系统中的断层相互作用。通过这个项目，我们将对断裂带内部结构、破裂过程和地震周期之间的关系有更好的了解。了解断层结构的时空变化，将有助于更真实地反映断层强度变化的宏观表现，以及断层段和断层网络的动态响应，并有助于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.