Electromagnetic Imaging of Fluids in the San Andreas Fault: Collaborative Research with University of Washington and Oregon State University

小行星9614411 这是俄勒冈州州立大学和华盛顿大学之间的一个合作项目，目的是获取和解释圣安德烈亚斯断层（SAF）两段的高分辨率大地电磁（MT）数据。 在以前的工作中，P.I.利用连续的MT剖面数据，获得了帕克菲尔德段4公里深处的高分辨率电阻率图像，揭示了断层核心的一个狭窄的异常低电阻率区域。 在该项目的第一阶段，他们将继续在帕克菲尔德工作，收集更多的剖面横跨圣安德烈亚斯断层附近的中山，以获得该地区的三维电阻率图像。 为了将图像扩展到孕震深度，他们将在距离断层20公里的地方采集MT数据，并将使用受控源 勘探方法在第二阶段，将在加州的霍利斯特附近对圣安德烈亚斯断层的中央蠕动段进行三维高分辨率勘测。 由于地壳岩石的电阻率在很大程度上受流体含量的控制，这些测量将 允许对断层带内流体的分布和连通性进行约束，并显示HMW，这些性质在具有不同机械行为的段之间变化。这些结果有望最终提供有关流体在地震过程中的作用的重要信息。 ***

9614411 Egbert This is a collaborative project between Oregon State University and the University of Washington to acquire and interpret high resolution magnetotelluric (MT) data across two segments of the San Andreas Fault (SAF). In previous work the P.Is. have used continuous MT profiling data to obtain high resolution images of electrical resistivity to depths of 4 km across the Parkfield segment, revealing a narrow zone of anomalously low resistivity in the core of the fault. In the first phase of this project, they will continue work at Parkfield, collecting additional profiles across the San Andreas Fault near Middle Mountain, to obtain a three-dimensional image of electrical resistivity in this area. To extend the image to seismogenic depths they will take MT data at distances of up to 20 km from the fault, and will employ controlled source exploration methods. In the second phase, a three-dimensional high resolution survey of the central creeping segment of the San Andreas fault will be conducted near Hollister, California. Because the resistivity of crustal rocks is largely controlled by fluid content, these surveys will allow constraints to be placed on the distribution and connectivity of fluids within the fault zone, and to show hmw these properties vary between segments with different mechanical behaviors. These results are expected to ultimately provide important information on the role of fluids in the earthquake process. ***