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

圣安德烈亚斯断裂系纬度处的太平洋-北美右旋相对板块运动约为50毫米/年。高达四分之一的运动是由位于加州东部剪切带内圣安德烈亚斯断层系统以东的断层上的位移以及位于西部盆地和山脉省、加利福尼亚州东部和内华达州西部的沃克巷系统提供的。与圣安德烈亚斯系统不同，北沃克巷断裂系统相对不成熟和复杂，使得大地测量速率和地质速率之间的比较变得困难。目前的数据表明，在西部盆地和山脉中，矩释放速率(通过偏移标志的地质观测和古地震调查获得)和应变能积累速率(通过地表形状变化的大地测量估计)之间存在系统差异。目前对这种差异缺乏了解可能在于关于应变释放的数据不完整(从构造、地形和地震的时空分布来看)，以及在复杂的大陆内部环境中基于应变累积的滑移率分辨率(如大地测量学所见)。该项目是对沃克湖和太浩湖之间的沃克巷北部地区进行的综合新构造和大地测量分析，该地区的新构造数据非常少。为了评估应变累积和释放的预算之间的差异，内华达大学雷诺分校的一个研究小组将获得迄今为止最完整的大陆内地震周期这两种表现的测量结果。该项目使用现有或即将安装的网络(Bargen、Magnet、NEARNET和地球望远镜板块边界观测站)提供的大地测量数据，并辅之以一个新的大地测量网络，该网络采用半连续观测战略，以获得研究区目前可用高精度的大约三倍。各种新构造方法将被用来研究史密斯、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裂。调查的规模将在这两个学科的优势之间实现最大程度的重叠，小到足以获得具有代表性的地质记录，大到足以解决大地应变场中可能与地壳断层模式有关的变化。这项工作与地球望远镜的目标是一致的。具体地说，要完全了解任何板块边界的运动学和力学，就需要测量整个边界在地质时间内的变形速度、类型和演化。这项研究的结果将有助于了解这一地震活跃区的地震危害。

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.