Milliner C W D, Sammis C, Allam A A, Dolan J F, Hollingsworth J, Leprince S, Ayoub F
Department of Earth Sciences, University of Southern California, Los Angeles, California 90089, USA.
Geology and Geophysics, The University of Utah, Salt Lake City, Utah 84112, USA.
Sci Rep. 2016 Jun 3;6:27201. doi: 10.1038/srep27201.
Fault slip distributions provide important insight into the earthquake process. We analyze high-resolution along-strike co-seismic slip profiles of the 1992 Mw = 7.3 Landers and 1999 Mw = 7.1 Hector Mine earthquakes, finding a spatial correlation between fluctuations of the slip distribution and geometrical fault structure. Using a spectral analysis, we demonstrate that the observed variation of co-seismic slip is neither random nor artificial, but self-affine fractal and rougher for Landers. We show that the wavelength and amplitude of slip variability correlates to the spatial distribution of fault geometrical complexity, explaining why Hector Mine has a smoother slip distribution as it occurred on a geometrically simpler fault system. We propose as a physical explanation that fault complexity induces a heterogeneous stress state that in turn controls co-seismic slip. Our observations detail the fundamental relationship between fault structure and earthquake rupture behavior, allowing for modeling of realistic slip profiles for use in seismic hazard assessment and paleoseismology studies.
断层滑动分布为地震过程提供了重要的见解。我们分析了1992年Mw = 7.3的兰德斯地震和1999年Mw = 7.1的赫克托矿地震的高分辨率沿走向同震滑动剖面，发现滑动分布的波动与断层几何结构之间存在空间相关性。通过频谱分析，我们证明观测到的同震滑动变化既不是随机的也不是人为的，而是自仿射分形的，且兰德斯地震的更为粗糙。我们表明，滑动变化的波长和幅度与断层几何复杂性的空间分布相关，这解释了为什么赫克托矿地震发生在几何结构更简单的断层系统上，其滑动分布更平滑。我们提出一个物理解释，即断层复杂性会导致非均匀应力状态，进而控制同震滑动。我们的观测详细阐述了断层结构与地震破裂行为之间的基本关系，从而能够模拟出用于地震危险性评估和古地震学研究的实际滑动剖面。
