Integrated Geologic and Geodetic Study of Strain Accumulation and Release in the Northern Walker Lane

沃克巷北部应变积累和释放的综合地质和大地测量研究

• 批准号: 0635757
• 负责人: Steven Wesnousky
• 金额: $ 33.49万
• 依托单位: Board of Regents, NSHE, obo University of Nevada, Reno
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-01-01 至 2010-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0635757&HistoricalAwards=false
• 关键词: Integrated; Geologic; Geodetic; Study; Strain

Pacific-North American right-lateral relative plate motion at the latitude of the San Andreas fault system is approximately 50 mm/yr. Up to one fourth of that motion is accommodated by displacements on faults east of the San Andreas fault system within the Eastern California shear zone and Walker Lane system located in the western Basin and Range province, eastern California and western Nevada. Unlike the San Andreas system, the relative immaturity and complexity of the northern Walker Lane fault system makes the comparison between geodetic and geologic rates difficult. Current data indicate that there is a systematic difference between rates of moment release (obtained from geologic observations of offset markers and paleoseismic investigations), and rates of strain energy accumulation (estimated from geodetic measurement of surface shape change) in the western Basin and Range. The current lack of understanding of this discrepancy may lie in the incompleteness of data on strain release (as seen through structure, physiography, and the spatial and temporal distribution of earthquakes) and the resolution of slip rates based on strain accumulation (as seen by geodesy) in a complex intra-continental setting. This project is an integrated neotectonic and geodetic analysis of the northern Walker Lane in the area between Walker Lake and Lake Tahoe, a region for which the neotectonics data are very minimal. In order to evaluate the difference between budgets of strain accumulation and release a University of Nevada at Reno research team will obtain the most complete measurements to date of these two manifestations of the earthquake cycle in an intra-continental setting. The project uses geodetic data from existing or soon-to-be installed networks (BARGEN, MAGNET, NEARNET, and the EarthScope Plate Boundary Observatory) that will be supplemented with a new geodetic network that uses a semi-continuous observation strategy to obtain roughly three times as many high precision rates as are currently available in the study area. A variety of neotectonic approaches will be used to study the faults bounding the Smith, Mason, Antelope and Bridgeport Valleys and long the Wakuska and Carson lineaments. The scale of the investigation will achieve a maximum in overlap between the strengths of the two disciplines, small enough to obtain a geologic record that is representative, and large enough to resolve variations in the geodetic strain field that can be related to crustal fault patterns. This work is in concert with the goals of EarthScope. Specifically, a complete understanding of the kinematics and mechanics of any plate boundary requires measurements of the rate, style, and evolution of deformation across the entirety of the boundary through geologic time. Results from this study will aid in understanding earthquake hazards in this seismically active region.

在圣安德烈亚斯断层系统的纬度上，太平洋-北美的右旋相对板块运动约为50毫米/年。该运动的四分之一由位于西部盆地山脉省、东部加州和西部内华达州的东加州剪切带和步行者巷系统内的圣安德烈亚斯断层系统以东的断层上的位移调节。与圣安德烈亚斯系统不同，北方步行者巷断层系统相对不成熟和复杂，使得大地速率和地质速率之间的比较变得困难。目前的数据表明，有一个系统的差异之间的时刻释放率（从地质观测的偏移标记和古地震调查），应变能积累率（估计从大地测量的表面形状变化）在西部盆地和山脉。目前缺乏对这种差异的理解可能在于应变释放数据的不完整性（通过结构，自然地理和地震的空间和时间分布）和基于应变积累的滑动速率分辨率（通过大地测量）在复杂的大陆内设置。该项目是对步行者湖和太浩湖之间地区的北方步行者巷的新构造和大地测量综合分析，该地区的新构造数据非常少。为了评估应变积累和释放的预算之间的差异，内华达州里诺大学的一个研究小组将获得迄今为止最完整的测量结果，这两种表现形式的地震周期在一个大陆内的设置。该项目使用现有或即将安装的网络（BARGEN、MAGNET、NEARNET和EarthScope板块边界观测站）的大地测量数据，并将补充一个新的大地测量网络，该网络采用半连续观测战略，以获得大约三倍于研究区域现有精度的高精度率。各种新构造方法将用于研究史密斯、梅森、羚羊和布里奇波特山谷以及瓦库斯卡和卡森线性构造的边界断层。调查的规模将在两个学科的优势之间实现最大的重叠，小到足以获得具有代表性的地质记录，大到足以解决可能与地壳断层模式有关的大地应变场的变化。这项工作与地球观测的目标是一致的。具体来说，要完全了解任何板块边界的运动学和力学，需要测量整个地质时期整个边界的变形速率、类型和演化。这项研究的结果将有助于了解这个地震活跃区的地震灾害。