Present-day strain accumulation and slip rates associated with southern San Andreas and eastern California shear zone faults
Present-day strain accumulation and slip rates associated with southern San Andreas and eastern California shear zone faults
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DOI：
10.1029/2010jb007424
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发表时间：
2010-11
影响因子：
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通讯作者：
J. Spinler;R. Bennett;M. Anderson;S. McGill;S. Hreinsdóttir;A. T. McCallister
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文献类型：
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作者：
J. Spinler;R. Bennett;M. Anderson;S. McGill;S. Hreinsdóttir;A. T. McCallister
[1]我们提出的第一个结果，从一个密集的网络的36个运动和46个连续的GPS站位于东横岭省（ETR），最南端的圣安德烈亚斯断层（SSAF）和东部加州剪切带（ECSZ）之间的过渡区。我们分析了1994-2009年期间的活动数据以及来自连续GPS站的可用数据。我们使用GPS速度估计来约束弹性块体模型，以研究代表不同断块几何形状的四种假设的断层加载率。断块情景包括以东向左侧平托山、蓝切和奇里亚科断层为边界的断块;以右向北-西北走向构造（“兰德斯-莫哈韦地震线”）为边界的断块，该构造斜穿过东向断层和绘制的莫哈韦沙漠断层;以及这些端元假设的组合。每个模型意味着显着不同的活动断层的几何形状，块旋转速率，以及ETR和ECSZ结构的滑动速率。所有模型都表明，SSAF滑动速率沿着走向变化明显，通常与构造地貌学和古地震学得出的速率一致，沿着最南端的Coachella山谷链最大为23毫米/年，通过San Gorgonio Pass区域系统地降低到<10毫米/年。对于所有测试的模型，圣哈辛托断层的滑动速率估计为12 mm/年。从统计学意义上讲，所有四个模型都能很好地拟合数据。模型之间的定性比较和考虑地质滑动速率和其他独立的数据揭示了每个模型的优点和缺点。
[1] We present the first results from a dense network of 36 campaign and 46 continuous GPS stations located in the Eastern Transverse Ranges Province (ETR), a transition zone between the southernmost San Andreas fault (SSAF) and eastern California shear zone (ECSZ). We analyzed the campaign data together with available data from continuous GPS stations for the period 1994–2009. We used the GPS velocity estimates to constrain elastic block models to investigate fault-loading rates representing four hypotheses characterized by different fault-block geometries. Fault-block scenarios include blocks bounded by the east-striking left-lateral Pinto Mountain, Blue Cut, and Chiriaco faults of the ETR; blocks bounded by a right-lateral north-northwest striking structure (the “Landers-Mojave earthquake line”) that cuts obliquely across the ETR and mapped Mojave Desert faults; and combinations of these end-member hypotheses. Each model implies significantly different active fault geometries, block rotation rates, and slip rates for ETR and ECSZ structures. All models suggest that SSAF slip rate varies appreciably along strike, generally consistent with rates derived from tectonic geomorphology and paleoseismology, with a maximum of ∼23 mm/yr right-lateral along the southernmost Coachella Valley strand, decreasing systematically to <10 mm/yr right-lateral through the San Gorgonio Pass region. Slip rate estimates for the San Jacinto fault are ∼12 mm/yr for all models tested. All four models fit the data equally well in a statistical sense. Qualitative comparison among models and consideration of geologic slip rates and other independent data reveals strengths and weaknesses of each model.