Collaborative Research: Spatial and Temporal Evolution of an Active Blind-Thrust Fault from Inception to the Most Recent Earthquake

合作研究：活动盲冲断层从发生到最近地震的时空演化

• 批准号: 0711170
• 负责人: James Dolan
• 金额: --
• 依托单位: University of Southern California
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-07-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0711170&HistoricalAwards=false
• 关键词: Collaborative; Research; Spatial; Temporal; Evolution

This research project is focused on deciphering paleo-earthquake records for thrust faults systems through geological and geophysical investigations of folds that develop above them. In the case of blind-thrust faults, these fault-related folds provide the only discernable record of paleo-earthquake activity on the underlying faults, and surface fold scarps in their own right present a potentially significant surface deformation hazard. Scientists from Harvard University and University of Southern California are examining a series of buried folds scarps above the active Puente Hills blind-thrust fault in the Los Angeles basin, California, to determine how they constrain past earthquake histories. The approach involves analysis of petroleum-industry reflection data, acquisition of multi-scale, high-resolution seismic reflection imagery, and excavation of detailed borehole transects to document and directly sample the youngest folded strata. Seismic reflection and borehole data will be collected above all three segments of this fault system, thus facilitating a comprehensive analysis of fault system behavior. Moreover, to elucidate the relative constancy of fold growth and fault slip rate over the past approximately 100,000 years, a deep (about 220 meters deep) continuously cored borehole will be drilled directly into the well-defined growth strata above the western, Los Angeles segment of the Puente Hills blind-thrust fault. Collectively, these data will help define what components of folding occur seismically, how various segments of a blind-thrust system interact over many rupture cycles, and how slip rates on these faults vary over different time scales, ranging from seismic cycles to millions of years.The motivations for this study are to understand the fundamental mechanism of blind-thrust faulting and folding, as well as to develop better methods of assessing regional earthquake hazards. The Puente Hills blind thrust underlies the heart of metropolitan Los Angeles and, because of its size and location, represents one of the worst deterministic seismic hazards in the United States. This study will help define the likely magnitude and frequency of future earthquakes on this fault, thereby improving the understanding of regional earthquake hazards. Moreover, the methodology developed through this study will prove readily exportable and thus serve as a tool to learn more about potentially dangerous faults around the world.

该研究项目的重点是通过对它们上方发展的褶皱的地质和地球物理研究来解密推力故障系统的古质量记录。在盲目性断层的情况下，这些与故障相关的褶皱提供了唯一可辨别的在基础断层上的古去Quake活动的记录，而其右侧的表面褶皱斜杆本身呈现出潜在的显着表面变形危险。哈佛大学和南加州大学的科学家正在研究加利福尼亚州洛杉矶盆地的活跃的普恩特山丘上方的一系列埋藏式疤痕，以确定它们如何限制过去的地震历史。该方法涉及分析石油 - 行业反射数据，获取多尺度，高分辨率地震反射图像以及详细的钻孔样带的发掘以记录并直接采样最年轻的折叠层。地震反射和钻孔数据将在此断层系统的所有三个段之上收集，从而促进对断层系统行为的全面分析。此外，为了阐明过去大约100，000年的折叠生长和断层滑移速率的相对稳定性，将直接钻入洛杉矶西部上方的良好定义的生长层（约220米深）连续核心钻孔Puente Hills盲目的断层。总的来说，这些数据将有助于定义折叠发生的组成部分，在许多破裂周期中，盲人系统的各个段如何相互作用，以及这些故障的滑移速率如何在不同的时间尺度上变化，从地震周期到数百万年这项研究的动机是了解盲目断层和折叠的基本机制，以及开发评估区域地震危害的更好方法。普恩特山（Puente Hills）盲目的推力是大都会洛杉矶的心脏的基础，并且由于其规模和位置，这代表了美国最严重的确定性地震危害之一。这项研究将有助于定义此断层上未来地震的可能性和频率，从而提高对区域地震危害的理解。此外，通过这项研究开发的方法将很容易出口，因此可以作为一种了解世界各地潜在危险故障的工具。