High-Resolution Lithospheric Velocity Structure of Continental China by Double-Difference Seismic Travel-Time Tomography
High-Resolution Lithospheric Velocity Structure of Continental China by Double-Difference Seismic Travel-Time Tomography
复制标题
双差地震走时层析成像中国大陆高分辨率岩石圈速度结构
DOI：
10.1785/0220180209
复制
发表时间：
2019-01-01
影响因子：
3.3
通讯作者：
Gao, Ji
中科院分区：
文献类型：
--
作者：
Xin, Hailiang;Zhang, Haijiang;Gao, Ji
为了确定中国大陆岩石圈的高分辨率V-P和V-S模型，我们收集了中国数字地震台网记录的11953次地震的大量高质量到达时间数据。采用双差（DD）地震层析成像同时确定地震位置和V-P和v (S)模型。依次使用网格间隔为1度和0.5度的两个反演网格。采用粗网格的速度倒转模型作为细网格的初始模型。在粗网格反演中，采用基于环境噪声层析成像的三维V-S模型和基于V-P与V-S之间经验关系的转换V-P模型作为初始模型。棋盘分辨率测试表明，在当前数据配置下，V-P和V-S模式在中国大陆大部分地区水平方向的空间分辨率为1度，在中国东部最高可达0.5度。利用有效震源的到达时间和表面波数据进一步验证了速度倒置模型。V-P模型也与深部地震测深剖面一致。150 km以下地壳和上地幔的高分辨率V-P和V-S模型为研究中国大陆地下构造提供了重要的约束条件。为了便于参考，我们将反演速度模型命名为USTClitho 1.0（中国大陆岩石圈统一地震层析成像模型）。总的来说，我们在浅层地壳的层析成像图像与地表地质很好地相关。
To determine high-resolution V-P and V-S models of the lithosphere of continental China, we assembled numerous highquality arrival-time data from 11,953 earthquakes recorded by the China Digital Seismic Network. Double-difference (DD) seismic tomography is applied to simultaneously determine earthquake locations and V-P andV(S) models. Two inversion grids with grid intervals of 1 degrees and 0.5 degrees are sequentially used. The inverted velocity models with the coarser grid are used as the initial models for the finer grid. For the inversion with the coarser grid, the 3D V-S model from ambient noise tomography and the converted V-P model based on an empirical relationship between V-P and V-S are used as the initial models. The checkerboard resolution test shows that with the current data configuration both V-P and V-S models down to 150 km have a spatial resolution of 1 degrees in the horizontal direction in most of continental China and up to 0.5 degrees in eastern China. The inverted velocity models are further validated by arrival times from active sources and surface-wave data. The V-P model is also consistent with that along the deep seismic sounding (DSS) profile. High-resolution V-P and V-S models of crust and upper mantle down to 150 km provide important constraints on tectonics beneath continental China. We name the inverted velocity models as USTClitho 1.0 (Unified Seismic Tomography models for continental China lithosphere) for easy reference. Overall, our tomographic images in the shallow crust correlate well with surface geology. In the deeper part, our velocity models show some well-known features, such as a low-velocity layer in the middle crust beneath the Tibetan plateau (TP) and a thin lithosphere beneath the North China craton.