Evolution of fault-surface roughness with slip
Evolution of fault-surface roughness with slip
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DOI：
10.1130/g23235a.1
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发表时间：
2007-03
期刊：
影响因子：
5.8
通讯作者：
A. Sagy;E. Brodsky;G. Axen
中科院分区：
文献类型：
--
作者：
A. Sagy;E. Brodsky;G. Axen
断裂带的主要滑动面容纳了地震期间的大部分位移。这些表面的地形是地震和断层力学的组成部分，但在地震滑动的规模上几乎是未知的。我们使用新的基于激光的方法在10微米到120米的尺度上绘制了暴露的断层表面。这些数据首次提供了断层表面粗糙度随着滑移量的增加而演变的第一个定量证据。数千条长度从10微米到100米不等的断层表明，小滑动断层(滑动1米)比平行于滑动方向的大滑动断层(滑动10-100米或更多)更粗糙。小滑动断层的表面在整个观测尺度范围内都具有凹凸性，而大滑动断层表面是光滑的，在长达1-2m的凹陷上的均方根值为~lt；3 mm。大滑动断层的表面呈光滑、拉长的准椭圆形凸起，长达数米，高达约1m，我们推测这些凸起是在断层成熟过程中演化的。这种几何学上的差异意味着，演化断层上的地震的成核、增长和终止与新断层上的地震有根本的不同。
Principal slip surfaces in fault zones accommodate most of the displacement during earthquakes. The topography of these surfaces is integral to earthquake and fault mechanics, but is practically unknown at the scale of earthquake slip. We use new laser-based methods to map exposed fault surfaces over scales of 10 µm to 120 m. These data provide the fi rst quantitative evidence that fault-surface roughness evolves with increasing slip. Thousands of profi les ranging from 10 µm to >100 m in length show that small-slip faults (slip <1 m) are rougher than large-slip faults (slip 10‐100 m or more) parallel to the slip direction. Surfaces of small-slip faults have asperities over the entire range of observed scales, while large-slip fault surfaces are polished, with RMS values of <3 mm on profi les as long as 1‐2 m. The large-slip surfaces show smooth, elongate, quasi-elliptical bumps that are meters long and as high as ~1 m. We infer that these bumps evolve during fault maturation. This difference in geometry implies that the nucleation, growth, and termination of earthquakes on evolved faults are fundamentally different than on new ones.