Quantitative morphology of bedrock fault surfaces and identification of paleo-earthquakes
Quantitative morphology of bedrock fault surfaces and identification of paleo-earthquakes
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基岩断层面定量形态与古地震识别
DOI：
10.1016/j.tecto.2016.09.032
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发表时间：
2016-12
期刊：
影响因子：
2.9
通讯作者：
er Densmore
中科院分区：
文献类型：
--
作者：
Honglin He;Zhanyu Wei;Alex;er Densmore
基岩断层面形态特征的定量分析可能是研究断层历史和识别古地震的有效手段。它是挖沟技术的有效补充，特别是在无法应用挖沟技术的基岩区域识别古地震。本文利用各向同性经验变异函数计算了山西地堑霍山山前断层三个基岩断层面的二维分形维数。我们表明，分形维数随着断层表面暴露底部上方的高度而系统地变化，表明断层表面形态的分割。我们将这种分割解释为由于周期性地震和不连续风化引起的平行断层表面带的暴露持续时间不同。我们以各条带分形维数的平均值作为描述其表面形态的特征值，可以用来估计断层表面条带的暴露持续时间，进而估计该条带暴露的地震发生时间。结合前期挖沟结果，拟合出暴露时间与断层形态特征值之间的经验关系：D=0.049T+2.246。这些断层面带的平均宽度也可以看作类似于1303年洪洞8级地震的特征地震的近似垂向同震位移。通过对霍山山前断层上3个断层面的定量形态分割，识别出3个地震事件。霍山山前断层特征地震的同震垂直位移估计为 3-4 m，即这些断层表面带的平均宽度。相邻两条带之间宽度为0.1-0.3 m的间隙，其分形值随着断层表面高度的增加而逐渐增大，推测是由两次地震之间的风化或断层上的震间滑移引起的。
The quantitative analysis of morphologic characteristics of bedrock fault surfaces may be a useful approach to study faulting history and identify paleo-earthquakes. It is an effective complement to trenching techniques, especially to identify paleo-earthquakes in a bedrock area where trenching technique cannot be applied. In this paper, we calculate the 2D fractal dimension of three bedrock fault surfaces on the Huoshan piedmont fault in the Shanxi Graben, China using the isotropic empirical variogram. We show that the fractal dimension varies systematically with height above the base of the fault surface exposures, indicating a segmentation of the fault surface morphology. We interpret this segmentation as being due to different exposure duration of parallel fault surface bands, caused by periodical earthquakes, and discontinuous weathering. We take the average of fractal dimensions of each band as a characteristic value to describe its surface morphology, which can be used to estimate the exposure duration of the fault surface band and then the occurrence time of the earthquake that exposed the band. Combined with previous trenching results, we fit an empirical relationship between the exposure duration and the morphological characteristic value on the fault:D= 0.049T +2.246. The average width of those fault surface bands can also be regarded as an approximate vertical coseismic displacement of characteristic earthquake similar to the Hongdong M8 earthquake of 1303. Based on the segmentation of quantitative morphology of the three fault surfaces on the Huoshan piedmont fault, we identify three earthquake events. The coseismic vertical displacement of the characteristic earthquake on the Huoshan piedmont fault is estimated to be 3–4 m, the average width of these fault surface bands. Gaps with a width of 0.1–0.3 m between two adjacent bands, in which the fractal value increases gradually with fault surface height, are inferred to be caused by weathering between two earthquakes or interseismic slip on the fault.
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影响因子：
3
作者：
通讯作者：
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影响因子：
5.8
作者：
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DOI：
10.1130/0-8137-5401-1.83
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影响因子：
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作者：
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通讯作者：
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DOI：
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发表时间：
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期刊：
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影响因子：
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