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首页> 外文学位 >Paleoseismology of blind-thrust faults beneath Los Angeles, California: Implications for the potential of system-wide earthquakes to occur in an active fold-and-thrust belt.
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Paleoseismology of blind-thrust faults beneath Los Angeles, California: Implications for the potential of system-wide earthquakes to occur in an active fold-and-thrust belt.

机译：加利福尼亚洛杉矶下的盲冲断层的古地震学：对活动的褶皱冲断带中可能发生全系统地震的潜在影响。

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摘要

In order to understand the paleo-earthquake history and structural evolution of blind-thrust faults and their associated folds, I use a multi-disciplinary methodology to link blind faulting at seismogenic depths directly to near-surface fault-related folding. My research focused on two major blind-thrust systems beneath metropolitan Los Angeles, California; the Puente Hills thrust fault (PHT) and the Compton thrust fault. I acquired data from multiple study sites along both faults in order to analyze shallow, subsurface folding for individual thrust ramps and study the potential for system-wide earthquakes to occur in segmented blind-thrust systems.;To resolve how folds grow in response to slip on the underlying thrust ramps, I utilized a methodology that combines high-resolution seismic reflection profiles, borehole excavations, and cone penetration testing to analyze the overlying growth folds of segmented blind-thrust faults. These shallow data allow me to observe folding at multiple depths and identify discrete buried fold scarps formed during past earthquakes at study sites above individual thrust ramps of both the PHT and Compton thrust.;The results of this dissertation provide Holocene-Late Pleistocene slip rates from study sites above the Los Angeles, Santa Fe Springs, and Coyote Hills, segments of the PHT. I also determined slip rates for both the northern and southern segments of the Compton fault. In addition to fault slip rates, this research demonstrates that both the Puente Hills and Compton blind thrust faults have generated multiple, large-magnitude (Mw >7) earthquakes during the past 12-14 ka, and that both faults are capable of generating multi-segment ruptures. Moreover, this study provides insights into the detailed kinematics of earthquake-by-earthquake fold growth above the underlying blind thrust ramps. At all of the study sites, the borehole data show that the folded strata within the kink bands acquired their dips incrementally, suggesting that fold kinematics involves components of both kink-band migration and limb rotation. These analyses of the geometry and evolution of young, shallow growth structures have allowed me to decipher the previously unknown paleo-earthquake history of the PHT and Compton fault, providing the basis for effective seismic hazard analysis.
机译：为了了解古地震的历史和盲冲断层及其相关褶皱的构造演化，我使用了多学科的方法将震源深度的盲断层直接与近地表断层相关的褶皱联系起来。我的研究集中在加利福尼亚大都会洛杉矶以下的两个主要的盲推系统上。 Puente Hills逆冲断层（PHT）和Compton逆冲断层。我从两个断层的多个研究地点获取了数据，以便分析各个推力斜坡的浅层，地下折叠，并研究分段盲推系统中发生全系统地震的可能性。在下推力斜坡上，我采用了一种结合高分辨率地震反射剖面，井眼开挖和圆锥穿透测试的方法，以分析分段盲冲断层的上覆生长褶皱。这些浅层数据使我能够观察到多个深度的褶皱，并确定在过去地震中在PHT和Compton推力的单个推力斜坡以上的研究地点形成的离散的隐匿褶皱陡坡;本论文的结果提供了全新世晚更新世滑移率。洛杉矶，圣达菲斯普林斯和土狼山（PHT的一部分）上方的研究地点。我还确定了康普顿断层北部和南部断层的滑移率。除断层滑移率外，这项研究还表明，在过去的12-14 ka期间，普恩特山丘陵和康普顿盲区逆冲断层都产生了多个大震级（Mw> 7），并且两个断层都能够产生多级地震。段破裂。此外，这项研究提供了深入的运动学见解，这些运动学是在潜在的盲逆推力斜坡之上的逐次地震褶皱生长的。在所有研究地点，钻孔数据表明，扭结带内的褶皱地层逐渐获得了倾角，这表明褶皱运动学涉及扭结带迁移和肢体旋转。对年轻的浅层生长结构的几何形状和演化的这些分析，使我得以解读PHT和Compton断层以前未知的古地震历史，为有效的地震危险性分析提供了基础。

著录项

  • 作者

    Leon, Lorraine Annette.;

  • 作者单位

    University of Southern California.;

  • 授予单位 University of Southern California.;
  • 学科 Geology.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 266 p.
  • 总页数 266
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 地质学;
  • 关键词

  • 入库时间 2022-08-17 11:38:28

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