根据SAFOD导向孔中的声波体波推断，圣安德烈亚斯断裂是否为刺刀形断裂？
Is the San Andreas Fracture a bayonet-shaped fracture as inferred from the acoustic body waves in the SAFOD Pilot hole ?
摘要：
利用声体波在垂直井眼周围应力修正区内传播的方法已被应用于圣安德列阿斯断层迹线附近SAFOD先导孔穿透的花岗岩地层。这种方法使我们能够研究水平地应力。只有P波提供了有用和令人惊讶的信息。1270 m的深度将应力修改区域的均匀厚度的上部区域（可能对应于剪切域）和下部区域（其中同时存在应力修改区域的厚度的两个值（特别是在1500和1600 m之间的深度），可能对应于压缩域和剪切域）分开。为了整合在某些深度的剪切和压缩域，以及在特定深度的三个剪切带的存在下，剪切的矛盾效果，我们建议，圣安德列阿斯断层可以是刺刀形的，而不是平面。其他最近在文献中关于这个故障，如存在一个低剪切波速度的断层带，应力旋转测量与深度，和大角度的摩擦系数，可以从逻辑上解释这种故障的几何形状。
英文摘要：
The method using the propagation of acoustic body waves within the stress modified areas around a vertical borehole has been applied to the granitic formation penetrated by the SAFOD Pilot hole near the San Andreas Fault trace. This method allows us investigating the horizontal in situ stresses. Only P waves supplied useful and surprising information. A depth of 1270 m separates an upper region of uniform thickness of stress modified areas, possibly corresponding to a shear domain, and a lower region where there are simultaneously two values of the thicknesses of the stress modified areas (particularly between 1500 and 1600 m of depth) possibly corresponding to a compressive and a shear domain. In order to integrate the contradictory effects of the simultaneity of shear and compressive domains at some depths, as well as the presence of three shear zones at particular depths, we propose that the San Andreas Fault could be bayonet-shaped instead of planar. Other recent available information in the literature about this fault, such as the presence of a fault zone of low shear wave velocity, stress rotation measured with depth, and the large angles of the frictional coefficients, can be logically explained by this kind of fault geometry.
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