Lack of continuity of the San Andreas Fault in southern California: Three-dimensional fault models and earthquake scenarios
Lack of continuity of the San Andreas Fault in southern California: Three-dimensional fault models and earthquake scenarios
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DOI：
10.1029/2003jb002643
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发表时间：
2004-04-28
影响因子：
3.9
通讯作者：
Kao, H
中科院分区：
文献类型：
--
作者：
Carena, S;Suppe, J;Kao, H
[1]1200 km长的圣安德烈亚斯断层在南加州圣戈尔戈尼奥山口附近失去了明显的连续性[艾伦，1957]，鉴于该断层在活动加州构造中的主导作用，这提出了重大问题。在这个复杂的地区，圣安德烈亚斯断层系统的基本三维（3-D）几何学和运动学行为是什么？从莫哈韦沙漠到科切拉山谷的圣安德烈亚斯断裂，如果复杂的话，可能吗？我们已经探索了三维连续性的问题，在这个地区的60多个故障映射到深度为15-20公里的震源位置和震源机制。我们能够从圣戈尔戈尼奥山口附近的断层网络的3-D几何形状来约束圣安德烈亚斯断层带（SAF）的3-D几何形状。最有可能的配置是圣安德烈亚斯断层并入印第奥西北部的浅倾圣戈尔戈尼奥山口逆冲断层。我们的结论是，目前没有直接的连续性，而是一个网络的故障，和唯一的一种破裂可能的SAF在这个地区是一个复杂的破裂，涉及走滑和逆断层。全球定位系统的测量结果还表明，尽管根据偏移地质标记，过去一定发生过大的运动，但今天在该地区只发生了轻微的运动。应用我们关于断层几何学的发现，我们探索了几种简单的地震场景，以确定从莫哈韦沙漠到科切拉山谷的圣安德烈亚斯断层系统贯通破裂的最有利条件。
[1] The 1200-km-long San Andreas Fault loses its apparent continuity in southern California near San Gorgonio Pass [Allen, 1957], which raises significant questions given the dominant role of this fault in active California tectonics. What is the fundamental three-dimensional (3-D) geometry and kinematic behavior of the San Andreas fault system in this complex region? Is a throughgoing, if complex, San Andreas rupture from the Mojave Desert to the Coachella Valley possible? We have explored the issue of 3-D continuity by mapping over 60 faults in this region to depths of 15-20 km from hypocenter locations and focal mechanisms. We were able to constrain the 3-D geometry of the San Andreas fault zone (SAF) near San Gorgonio Pass from the 3-D geometry of the fault network surrounding it. The most likely configuration is for the San Andreas Fault to merge into the shallow-dipping San Gorgonio Pass thrust northwest of Indio. We concluded that there is no direct continuity at present but rather a network of faults, and the only kind of rupture possible for the SAF in this region is a complex rupture, involving both strike-slip and reverse faulting. GPS measurements also suggest that despite the fact that large motions must have occurred in the past based on offset geologic markers, only minor motion is occurring today in this area. Applying our findings about the fault geometry, we explored several simple earthquake scenarios to determine the most favorable conditions for a throughgoing rupture of the San Andreas fault system from the Mojave Desert to the Coachella Valley.