The Long-Term Dynamics and Evolution of Geometrically Complex Fault Systems

几何复杂断层系统的长期动力学和演化

• 批准号: 0409836
• 负责人: David Oglesby
• 金额: $ 16.23万
• 依托单位: University of California-Riverside
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0409836&HistoricalAwards=false
• 关键词: Long; Term; Dynamics; Evolution; Geometrically

Most earthquakes take place on geometrically complex fault systems rather than simple planar faults. Recent earthquakes on such fault systems have shown quite clearly the important effects of fault geometry on the dynamics of earthquake rupture, slip, and ground motion. This project is to study the dynamics of geometrically complex fault systems over multiple earthquake cycles using numerical simulations. Specific fault geometries to be addressed include faults with bends, faults with branches, and faults with offset segments. To accomplish this task, dynamic models for the earthquake rupture and slip process are being integrated with quasi-static models to simulate the processes of slow tectonic loading, nucleation, and post-seismic relaxation. An integrated algorithm to model these processes is being developed in this research. Using this technique, the researchers are modeling the complete earthquake cycle: initial stress distributions on faults before an earthquake rupture are a consequence of slow tectonic loading, stress relaxation, and residual stress from previous ruptures. Nucleation is also be spontaneously developed, and dynamic rupture patterns and ground motion are calculated. Thus, the long-term effects of fault geometry and characteristic behaviors of fault systems over multiple earthquake cycles are addressed in a self-consistent manner. The results will aid in the interpretation of recorded earthquakes on geometrically complex fault systems, such the Hector Mine and Chi-Chi events. The results will also aid in the prediction of future behavior of complex fault systems such as the San Andreas, as well as the ground motion during earthquakes on these faults.

大多数地震发生在几何形状复杂的断层系统上，而不是简单的平面断层上。 最近在这类断层系统上发生的地震已经清楚地表明，断层几何形状对地震破裂、滑动和地面运动的动力学有重要影响。本计画系利用数值模拟之方法，研究几何复杂断层系统在多个地震周期中之动态。要解决的具体断层几何形状包括弯曲断层、分支断层和偏移段断层。为了完成这一任务，地震破裂和滑动过程的动态模型正在与准静态模型相结合，以模拟缓慢的构造加载，成核和震后松弛的过程。一个综合的算法来模拟这些过程正在开发中，这项研究。 使用这种技术，研究人员正在模拟完整的地震周期：地震破裂前断层上的初始应力分布是缓慢的构造加载，应力松弛和先前破裂的残余应力的结果。 核化也是自发发展的，并计算了动态破裂模式和地面运动。因此，长期影响的断层几何形状和特征行为的断层系统在多个地震周期处理在一个自洽的方式。这些结果将有助于解释几何复杂断层系统上记录的地震，如赫克托矿和集集事件。研究结果还将有助于预测复杂断层系统（如圣安德烈亚斯断层）的未来行为，以及这些断层上地震时的地面运动。