Rupture Propagation and Arrest in Geometrically Complex Fault Systems: Bends, Stepovers, and Damaged Border Zones

建议摘要EAR-0105344(PH#37X)标题：在几何复杂的断层系统中的破裂传播和止裂：弯曲、陡峭和受损的边界地带PI的：詹姆斯·R·赖斯(首席研究员)和雷纳塔·德莫夫斯卡(高级联合研究员)，部门。关于地球和行星科学的。和Div.引擎号。和Appl.我们的项目试图了解在几何复杂的断层系统中控制地震破裂传播和阻止的力学原理。作为其中的一部分，我们正在设计数值方法来模拟动态破裂，包括断层表面的非平面性、断层网络中的跳跃和分支、在与主断裂带接壤的区域激活较小的断层或裂缝，以及同时激活竞争性破裂路径。通常，破裂路径不能预先指定，而是必须在网络的可用故障段中动态地自行选择。地质学、大地测量学和地震学观测被用来约束和测试关于破裂几何形状和主要应力状态(包括主应力方向)如何控制破裂是否沿着分支断裂构造开始、是否沿着分支持续很长距离、破裂传播的间歇性等发展想法。这些观测案例包括逆冲(San Fernando 1971，Kettleman Hills 1985)和走滑(Imperial Valley 1979，Landers 1992，Hector mine 1999)事件，这些事件似乎涉及分支和/或激活断层外活动。世界各地正在研究其他主要断层系统的例子，包括北安纳托利亚系统、沿着它的伊兹米特1999序列，以及它未来可能在伊斯坦布尔附近继续的情况。研究包括考虑能量如何在动态破裂中耗散，以及丰富的高频地震辐射的特征。

Abstract for proposal EAR-0105344 (PH # 37x)Title: Rupture propagation and arrest in geometrically complex fault systems: Bends, stepovers, and damaged border zonesPI's: James R. Rice (principal investigator) and Renata Dmowska (senior co-investigator), Dept. of Earth and Planetary Sci. and Div. of Engin. and Appl. Sci., Harvard Univ.Our project seeks to understand mechanical principles controlling earthquake rupture propagation and arrest in geometrically complex fault systems. As part of that we are devising numerical methodology to model dynamic rupture with inclusion of non-planarity of fault surfaces, step-overs and branches in fault networks, activation of smaller faults or fractures in the region bordering a main fault zone, and simultaneous activation of competitive rupture paths. In general the rupture path cannot be specified a priori but, rather, must be dynamically self-chosen among available fault segments of the network. Geological, geodetic and seismological observations are used to constrain and test developing ideas on how rupture geometry and prevailing stress state, including principal stress orientations, control whether a rupture starts along a branching fault structure, whether it continues for long distances along the branch, how intermittent is the rupture propagation, etc. Those observational cases include thrust (San Fernando 1971, Kettleman Hills 1985) and strike slip (Imperial Valley 1979, Landers 1992, Hector Mine 1999) events in which branching and/or activation of off-fault activity seem to be involved. Other examples are under study throughout the world for major fault systems, including the North Anatolian system, the Izmit 1999 sequence along it, and its possible future continuation near Istanbul.The studies include consideration of how energy is dissipated in dynamic rupture, and what are characteristics of the enriched high frequency seismic radiation.