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Geodetic investigations of active crustal deformation in the Philippine plate boundary zone and the intraplate region of the central United States.

机译：美国中部菲律宾板块边界带和板内区域主动地壳变形的大地测量研究。

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摘要

This thesis investigates active tectonic and volcanic deformation in two distinct plate tectonic settings: a plate boundary zone (PBZ) accommodating oblique plate convergence, and an intraplate continental seismic zone, using high-precision space geodetic techniques. The Philippine Mobile Belt (PMB), a seismically active, rapidly deforming PBZ situated along the convergent Philippine Sea/Eurasian plate boundary, is examined using geodetic and seismological data. Oblique convergence between the Philippine Sea Plate and the Sundaland/Eurasian Plate is accommodated by nearly orthogonal subduction along the Philippine Trench, East Luzon Trough, and the Manila Trench, as well as by strike-slip faulting along the Philippine Fault system. A kinematic model of active plate boundary deformation in this region is developed, using elastic block models constrained by known fault geometries, published GPS observations and focal mechanism solutions. I present an estimate of block rotations, fault coupling, and intra-block deformation, based on the best-fit model that minimizes the misfit between observed and predicted geodetic vectors and earthquake slip vectors. In the preferred model, the Philippine Mobile Belt can be represented by at least nine independently moving tectonic blocks, separated by active faults and subduction zones.;I also model active deformation patterns associated with magmatic activity at Taal Volcano, an active tholeiitic volcano located within the Taal caldera in southwestern Luzon. Elastic and combined elastic-viscoelastic modeling results are compared with observed deformation, measured by continuous GPS on and near the volcano. Continuous dual- and single-frequency (L1) GPS data (1998--2005) provide evidence for smoothly transitioning periods of inflation and deflation centered under Volcano Island. Elastic modeling of the source region indicates a relatively stable point source, located under Volcano Island's central crater, at ∼5 km depth with time-varying pressure/volume changes. I model finite-element models of volcanic deformation using an axisymmetric geometry, with a small spherical source and annuli of viscoelastic shells, embedded within a multi-layered elastic half-space. Using simply varying pressure histories as input, forward models are fit to the time history of continuously observed GPS deformation for both dual-frequency and L1 stations surrounding Taal Volcano relative to station KAYT, situated on the southwest side of Volcano Island. The use of viscoelastic shell models that incorporate geologically appropriate material properties provide simpler pressure histories that require significantly reduced overall pressure increases, relative to equivalently fitting purely elastic models.;In contrast to the Philippine PBZ, I investigate active intraplate crustal deformation within the southern Illinois Basin, which includes the Wabash Valley seismic zone, a faulted and seismically active area in the U.S. mid-continent, located north-northeast of the New Madrid seismic zone. I analyze GPS-derived velocity solutions for the region based on 11 years (1997--2008) of campaign observations at 67 sites in S. Indiana, S. Illinois and W. Kentucky. Improved estimates of site motions indicate a marginal but resolvable systematic north to NNW-oriented pattern of the GPS velocity vectors in the Stable North American Reference Frame (SNARF). I investigate internal deformation within this continental intraplate region, modeled as an area defined by relatively rigid elastic blocks with deformation concentrated along narrow zones of weaknesses or faults. Models based on a single continuously deforming plate indicate small areas of deformation localized in SE Illinois, SW Indiana and NW Kentucky, with seismicity and recent events possibly reflecting transpressional tectonics in the area.
机译：本论文利用高精度空间大地测量技术研究了两种不同板块构造环境下的活动构造和火山形变：一个板块边界带（PBZ）容纳斜板块汇聚，一个板块内地震带。菲律宾大地带（PMB）是地震活跃的，迅速变形的PBZ，位于汇聚的菲律宾海/欧亚板块边界，使用大地测量和地震数据进行了检查。沿菲律宾海沟，东吕宋海槽和马尼拉海沟的近乎正交的俯冲，以及沿菲律宾断层系统的走滑断层，都可以调节菲律宾海板块与Sun他兰/欧亚板块之间的斜交汇。使用受已知断层几何形状约束的弹性块模型，已发布的GPS观测值和震源机制解决方案，开发了该区域活动板块边界变形的运动学模型。我基于最佳拟合模型给出了对块旋转，断层耦合和块内变形的估计，该模型使观测和预测的大地矢量与地震滑动矢量之间的失配最小。在首选模型中，菲律宾移动带可以用至少9个独立运动的构造块表示，由活动断层和俯冲带隔开。我还对与塔尔火山岩浆活动有关的活动变形模式进行了建模，该活动位于塔尔火山中，吕宋岛西南部的塔尔火山口。将弹性和组合的粘粘弹性建模结果与观察到的变形进行比较，该变形是通过在火山上及其附近进行连续GPS测得的。连续双频和单频（L1）GPS数据（1998--2005）提供了以火山岛为中心的通货膨胀和通货紧缩阶段的平稳过渡时期的证据。震源区的弹性模拟表明，一个相对稳定的点震源位于火山岛中央火山口下方，深度约5 km，随压力/体积的变化而变化。我使用轴对称几何模型对火山变形的有限元模型进行建模，并在多层弹性半空间中嵌入了球形小源和粘弹性壳的环空。使用简单变化的压力历史作为输入，相对于位于火山岛西南侧的Taal火山周围的双频站和L1站（相对于KAYT站）而言，正向模型适合于连续观测GPS变形的时间历史。与等效拟合的纯弹性模型相比，使用结合了地质学上合适的材料特性的粘弹性壳模型可提供更简单的压力历史记录，而这些压力历史记录要求显着降低总压力增加量;与菲律宾PBZ相比，我研究了伊利诺伊州南部的活跃板内地壳变形盆地包括Wabash谷地震带，这是美国中部的断层和地震活跃区，位于新马德里地震带的东北部。我根据对印第安纳州，伊利诺伊州和肯塔基州W.的67个站点的11年（1997--2008）的运动观测结果分析了该地区的GPS速度解。改进的站点运动估计值表明，稳定北美参考系（SNARF）中GPS速度矢量的边际但可解决的北向NNW方向的系统格局。我研究了该板块内部的内部变形，该内部变形被建模为由相对刚性的弹性块定义的区域，变形集中在弱点或断层的狭窄区域。基于单个连续变形板的模型表明，伊利诺伊州东南部，印第安纳州西南部和肯塔基州西北部存在小范围的变形，地震活动和最近发生的事件可能反映了该地区的超压构造。

著录项

  • 作者

    Galgana, Gerald A.;

  • 作者单位

    Indiana University.;

  • 授予单位 Indiana University.;
  • 学科 Geodesy.;Geophysics.;Geology.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 253 p.
  • 总页数 253
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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