A comparative analysis of deformable layer tomography and cell tomography along the LARSE lines in southern California
A comparative analysis of deformable layer tomography and cell tomography along the LARSE lines in southern California
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DOI：
10.1111/j.1365-246x.2009.04472.x
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发表时间：
2010-03
影响因子：
2.8
通讯作者：
Hua-Wei Zhou;Li Li-Li;T. Bjorklund;M. Thornton
中科院分区：
文献类型：
--
作者：
Hua-Wei Zhou;Li Li-Li;T. Bjorklund;M. Thornton
摘要 我们利用当地地震初至和两条洛杉矶区域地震实验 (LARSE) 地震线，沿着南加州 P 波速度的三个二维地壳剖面，对新型变形层断层扫描 (DLT) 与传统的固定空间单元断层扫描进行了比较分析。 DLT 方法可反演速度界面随深度变化的几何形状，其中包括地壳顶部和底部附近的主要速度不连续性以及中地壳速度层之间的边界。在横向速度变化较大的区域中，与使用固定空间单元或网格的传统单元层析成像相比，DLT 方法可以提高主速度界面的深度分辨率。我们还测试了使用接收函数研究中的地壳厚度估计来限制莫霍面几何的深度范围。测试表明，在射线覆盖足够的区域，主要速度界面的DLT深度分辨率在上地壳中通常小于1 km，在下地壳中小于3 km。我们的 2-D DLT 模型与首次到达数据的拟合程度明显优于三个已发布的 3-D 细胞断层扫描模型。 DLT 模型很好地描绘了盆地边缘和起伏速度不连续性的配置，并表明了该地区的地壳结构。
SUMMARY We conducted a comparative analysis of the new deformable layer tomography (DLT) with the traditional fixed-in-space cell tomography along three 2-D crustal profiles of P-wave velocities in southern California using first arrivals from local earthquakes and two Los Angeles Regional Seismic Experiment (LARSE) seismic lines. The DLT method inverts for the depth-varying geometry of velocity interfaces, which include major velocity discontinuities near the top and bottom of the crust and boundaries between velocity layers in the middle crust. In regions characterized by large lateral velocity changes, the DLT method may improve the depth resolution of major velocity interfaces compared to traditional cell tomography using fixed-in-space cells or grids. We also tested the use of crustal thickness estimates from a receiver function study for constraining the depth range of the Moho geometry. Tests indicate that, in areas of sufficient ray coverage, the depth resolution of the DLT for major velocity interfaces is usually less than 1 km in the upper crust and less than 3 km in the lower crust. Our 2-D DLT models fit the first arrival data significantly better than three published 3-D cell tomography models along the profiles. The configurations of basin edges and undulating velocity discontinuities are well delineated in the DLT models and indicative of the crustal architecture of the region.