Spatial and temporal evolution of intracontinental shear zones: The Stateline fault system, Eastern California Shear Zone (USA)

我们提议对位于美国加州-内华达州边界的州线断层系统进行短期初步研究。该项目的基本目的是沿着该断层系统收集初步的地质、构造地貌和地球物理（小型地震调查）数据，目的是为该断裂带绘制新的构造地貌图，并为侧重于限制滑动率横向时空梯度的更大项目奠定基础。我们之所以选择关注Stateline断层，是因为它的年轻变形记录以前未被识别，而且根据初步的GPS数据，它似乎位于加利福尼亚东部剪切带内，该剪切带形成了太平洋板块和稳定的北美之间的边界区域。它相对于加利福尼亚东部剪切带的其余部分的演变，占太平洋-北美板块运动的大约25%，因此对我们理解控制大陆剪切带变形和传播等过程的因素很重要。这个地区也很重要，因为它是地震活跃的地区，包括几个大型人口中心（如拉斯维加斯）和北美最大的高放射性核废料储存设施（尤卡山）。我们计划在2007年野外季节（2月至5月）做以下工作：详细绘制断裂带的关键暴露部分（1:10 000至1:5 000比例），以确定最近发生破裂的断层段，并对这些断层段进行采样，以便为破裂事件建立时间约束。2. 在几个关键位置对断层系统进行地震调查，以限制断层带的宽度和几何形状。3. 为该断裂带的下一阶段工作确定有希望的海沟地点，以确定过去地震破裂的时空模式，以及断层上的长期滑动率（未来DFG提案）。

We propose a short-term preliminary study of the Stateline fault system, which lies on the California-Nevada border, USA. The basic aim of this project is to collect preliminary geologic, tectono-geomorphic and geophysical (small seismic survey) data along this fault system with the goal of producing a new tectono-geomorphic map for this fault zone and laying the ground work for a larger project focused on constraining lateral spatial and temporal gradients in slip-rate. We choose to focus on the Stateline fault because it s young deformation record was previously unrecognized and because, based on preliminary GPS data, it appears to lie within the eastern California shear zone, which forms the boundary region between the Pacific plate and stable North America. Its evolution relative to the rest of the eastern California shear zone, which account for approximately 25% of Pacific-North America plate motion, is therefore important to our understanding of the factors governing processes like continental shear zone deformation and propagation. This area is also important because it is seismically active and includes several large population centers (e.g. Las Vegas) and the largest proposed high-level nuclear waste storage facility in North America (Yucca Mountain). We plan to do the following during the 2007 field season (February through May): 1. Map critical exposed segments of the fault zone in detail (1:10,000 to 1:5,000 scale) to identify fault segments that have ruptured recently and to sample these segments in order to establish timing constraints for the rupture events. 2. Conduct a seismic survey across the fault system in several key locations to constrain the fault zone width and geometry. 3. To identify promising trench sites for the next phase of work on this fault zone in order to determine the space time patterns of past earthquake ruptures, and a longer term slip rate on the fault (future DFG proposal).