Topographic Characteristics of Rupture Surface Associated with the 12 May 2008 Wenchuan Earthquake
Topographic Characteristics of Rupture Surface Associated with the 12 May 2008 Wenchuan Earthquake
复制标题
2008年5月12日汶川地震破裂面地形特征
DOI：
10.1785/0120090260
复制
发表时间：
2010-11
影响因子：
3
通讯作者：
中科院分区：
文献类型：
--
作者：
准确地描述破裂面的形貌对于我们理解地震断层作用非常重要，因为破裂面的形貌特征包含了许多关于地震和断层力学的信息。使用 3D 便携式激光扫描仪扫描测量了 2008 年汶川 7.9 级地震的两个新鲜破裂面，即八角庙面和沙坝面。使用功率谱和均方根 (rms) 粗糙度对采集的数字高程模型 (DEM) 数据集进行分析。新鲜破裂面表现出自仿射行为，功率谱密度和均方根粗糙度均与剖面长度呈幂律关系。平行于滑移方向的表面的粗糙度通常小于垂直于滑移方向的表面的粗糙度。在功率谱密度与空间频率的双对数图中，存在明显的拐点，将空间频率分为低频域和高频域。八角庙表面拐点对应的波长为平行于滑移方向的 7 mm（补丁 I 和补丁 II 均如此），小于垂直于滑移方向的波长（补丁 I 为 10 mm，补丁 II 为 9 mm），平行于滑移方向为 8 mm，但大于垂直于滑移方向的波长（6 mm）。双对数图中均方根粗糙度曲线的最小二乘拟合线的斜率是 H 指数（也称为 Hurst 指数），它取决于剖面的方向，描述断层表面的形态各向异性。八角庙表面的最小H值85°和75°以及沙坝表面的45°所指示的滑移方向与现场观测到的滑移方向相同。沙坝破裂面的二次最小 H 值（160°）揭示了汶川地震前地震产生的一组隐藏条纹。此外，八角庙表面垂直滑移的地形剖面H值略大于0.8，而沙坝表面则远小于0.8，可能表明八角庙表面存在逆断层，沙坝表面存在正断层。通过轮廓全长上功率谱密度(-α)的斜率与均方根粗糙度(H)的斜率之间的线性拟合，可得增益关系：α=1.22+1.72×H。它不严格遵循理论关系α=1+2×H，可能是由数据中的噪声、破裂面的多重分形以及粗糙度的分析方法造成的。
It is very important to describe accurately the topography of rupture surfaces for our understanding of seismic faulting because the topographic characteristics of the rupture include much information about the earthquake and fault mechanics. Two fresh rupture surfaces of the M w 7.9 2008 Wenchuan earthquake, referred to as the Bajiaomiao surface and the Shaba surface, have been measured by scanning with a 3D portable laser scanner. The acquired sets of Digital Elevation Model (DEM) data are analyzed using power spectral and root mean square (rms) roughness. The fresh rupture surfaces exhibit self-affine behavior, and both the power spectral density and rms roughness have a power law relationship with the length of profiles. The roughness of the surface parallel to the slip direction is generally less than the roughness perpendicular to the slip direction. In a log–log plot of power spectral density versus spatial frequency, there is an obvious inflection that divides the spatial frequency into a lower-frequency domain and a higher-frequency domain. The wavelength corresponding to the inflection is 7 mm in the direction parallel to the slip for the Bajiaomiao surface (in both Patch I and Patch II), smaller than that in the direction perpendicular to the slip (10 mm in Patch I and 9 mm in Patch II), and 8 mm in the direction parallel to the slip, but larger than that in the direction perpendicular to the slip (6 mm). The slope of least-squares fitting line to the rms roughness curve in a log–log plot is the H exponent (also called the Hurst exponent), which depends on the direction of the profile and describes the morphological anisotropy of the fault surface. The slip directions indicated by the minimum H values, 85° and 75° on the Bajiaomiao surface and 45° on the Shaba surface, are equal to the slip directions observed in the field. A secondary minimum H value, 160° in the Shaba rupture surface, reveals a set of concealed striations produced by an earthquake prior to the Wenchuan earthquake. Moreover, the H value of the topographic profile perpendicular to the slip on the Bajiaomiao surface is slightly larger than 0.8, whereas it is quite smaller than 0.8 on the Shaba surface, probably indicating reverse faulting on the Bajiaomiao surface and normal faulting on the Shaba surface. Through linear fitting between the slopes of power spectral density (- α ) and the slopes of rms roughness ( H ) in the whole length of profile, a relationship can be gain, α =1.22+1.72× H . It does not adhere to theory relationship strictly, α =1+2× H , probably caused by the noise in the data, the multifractal of the rupture surface, and the analysis methods of roughness.
登录
查看更多内容
DOI：
10.5860/choice.28-1579
发表时间：
2016
期刊：
--
影响因子：
--
作者：
Leon Bieber
通讯作者：
Leon Bieber
影响因子：
5.8
作者：
A. Sagy;E. Brodsky;G. Axen
通讯作者：
A. Sagy;E. Brodsky;G. Axen
影响因子：
--
作者：
D. Schaff;D. Schaff;G. Bokelmann;G. Beroza;F. Waldhauser;F. Waldhauser;W. Ellsworth
通讯作者：
D. Schaff;D. Schaff;G. Bokelmann;G. Beroza;F. Waldhauser;F. Waldhauser;W. Ellsworth
影响因子：
3.1
作者：
Joong-Jeek Lee;R. Bruhn
通讯作者：
Joong-Jeek Lee;R. Bruhn
影响因子：
--
作者：
Stephen R. Brown;C. Scholz
通讯作者：
Stephen R. Brown;C. Scholz