Scientific Drilling Into the San Andreas Fault Zone —An Overview of SAFOD's First Five Years
Scientific Drilling Into the San Andreas Fault Zone —An Overview of SAFOD's First Five Years
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圣安德烈亚斯断层带科学钻探——SAFOD 前五年概述
DOI：
10.2204/iodp.sd.11.02.2011
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发表时间：
2011
影响因子：
1.2
通讯作者：
W. Ellsworth
中科院分区：
文献类型：
--
作者：
M. Zoback;S. Hickman;W. Ellsworth
在圣安德烈亚斯断层观测站（SAFOD）进行了钻探，以研究控制断层和地震发生的物理和化学过程，沿着一个活跃的板块边界断层。SAFOD位于加州帕克菲尔德附近，穿过由于重复微震和断层蠕动的组合而移动的断层的一部分。地球物理测井将圣安德烈亚斯断层带定义为相对较宽（~200 m），包含几个仅2-3 m宽的离散带，这些带显示出非常低的P波和S波速度和低电阻率。其中两个区域在3192 m和3302 m的测量深度处逐渐使水泥套管变形。从两个变形区的岩心包含一个普遍剪切，无粘性，叶理断层泥，符合套管变形，并解释了观察到的极低的地震速度和电阻率。这些岩心现在正在世界各地的实验室中进行广泛的测试，并对其组成，变形机制，物理性质和流变行为进行研究。井下测量表明，在活动断层痕迹的200米（最大）范围内，最大水平应力的方向与圣安德烈亚斯断层保持高角度，与其他测量结果一致。SAFOD主孔的结果，以及在先导孔确定的应力状态，与圣安德烈亚斯的强地壳/弱断层模型一致。地震仪器已被部署来研究断层地震成核，传播和逮捕的物理，以测试实验室衍生的概念如何扩大到地震发生的性质。
The San Andreas Fault Observatory at Depth (SAFOD) was drilled to study the physical and chemical processes controlling faulting and earthquake generation along an active, plate-bounding fault at depth. SAFOD is located near Parkfield, California and penetrates a section of the fault that is moving due to a combination of repeating microearthquakes and fault creep. Geophysical logs define the San Andreas Fault Zone to be relatively broad (~200 m), containing several discrete zones only 2–3 m wide that exhibit very low P- and S-wave velocities and low resistivity. Two of these zones have progressively deformed the cemented casing at measured depths of 3192 m and 3302 m. Cores from both deforming zones contain a pervasively sheared, cohesionless, foliated fault gouge that coincides with casing deformation and explains the observed extremely low seismic velocities and resistivity. These cores are being now extensively tested in laboratories around the world, and their composition, deformation mechanisms, physical properties, and rheological behavior are studied. Downhole measurements show that within 200 m (maximum) of the active fault trace, the direction of maximum horizontal stress remains at a high angle to the San Andreas Fault, consistent with other measurements. The results from the SAFOD Main Hole, together with the stress state determined in the Pilot Hole, are consistent with a strong crust/weak fault model of the San Andreas. Seismic instrumentation has been deployed to study physics of faulting—earthquake nucleation, propagation, and arrest—in order to test how laboratory-derived concepts scale up to earthquakes occurring in nature.
影响因子：
3.4
作者：
T. Wiersberg;J. Erzinger
通讯作者：
T. Wiersberg;J. Erzinger
影响因子：
3.7
作者：
T. Wiersberg;J. Erzinger
通讯作者：
T. Wiersberg;J. Erzinger