EPmantle: a 3-D transversely isotropic model of the upper mantle under the European Plate
EPmantle: a 3-D transversely isotropic model of the upper mantle under the European Plate
复制标题
EPmantle：欧洲板块下上地幔的 3D 横观各向同性模型
DOI：
10.1111/j.1365-246x.2011.04953.x
复制
发表时间：
2011
影响因子：
2.8
通讯作者：
A. Morelli
中科院分区：
文献类型：
--
作者：
R. Schivardi;A. Morelli
本文提出了一个新的欧洲和地中海三维横观各向同性剪切波速度模型，该模型是通过分析表面波获得的，数据是欧洲台站记录的区域地震记录上的周期范围为35-170 s的基模Rayleigh和Love群速度测量结果。层析反演映射的3-D地球结构分为两个步骤。首先，我们区域化的群速度频散测量，获得不同的地理群速度图在不同的时期，然后，每个本地的频散曲线分别反演，以找到剪切波速度结构在深度。利用三维全球地幔模型（S20 RTS）和新的详细欧洲地壳模型（EPcrust）的先验信息对浅层进行约束，使反演得到了很好的效果。反演方案遵循非线性迭代算法，通过该算法，瑞利和洛夫群慢度同时反演最佳拟合各向同性Voigt剪切波速度（2 vSV + 1 vSH）和径向各向异性参数（vSH − vSV）。最终合并的vS配置文件的结果在一个新的更高分辨率的欧洲上地幔的3-D模型。我们发现，西欧和地中海的主要特点是相对较低的速度，强烈对比的快速根的东欧地中海。模型中还显示了许多区域尺度结构，从而为了解欧洲大陆复杂的地球动力学框架提供了见解。最突出的是低速西地中海扩张盆地和欧洲新生代裂谷系统，以及与阿德里亚微板块、希腊弧和卡拉布里亚弧俯冲有关的地震快速特征。径向各向异性相对于PREM剖面变化不大，因为现有数据由于与速度的权衡，只能在有限程度上解决横向变化。EPmantle有可能为广大欧洲地区的上地幔结构提供可靠的地震学参考。
SUMMARY We present a new 3-D transversely isotropic shear wave velocity model of the European and Mediterraneanuppermantleobtainedbyanalysisofsurfacewaves.Datausedarefundamentalmode Rayleigh and Love group velocity measurements in the period range 35–170 s, taken on seismograms recorded by European stations for regional earthquakes. The tomographic inversion to map the 3-D earth structure is split into two steps. First, we regionalize the group velocity dispersion measurements, obtaining distinct geographical group velocity maps at different periods; then, each local dispersion curve is inverted separately to find the shear wave velocity structure at depth. The inversion benefits from using ap rioriinformation from a 3-D global mantle model (S20RTS) and a new detailed European crustal model (EPcrust) to constrain the shallower layers. The inversion scheme follows a non-linear iterative algorithm by which Rayleigh and Love group slowness are inverted simultaneously for the best-fitting isotropic Voigt shear wave speed ( 2 vSV + 1 vSH) and radial anisotropy parameter (vSH − vSV). Final merging of the vS profiles results in a new higher resolution 3-D model of European upper mantle. We find that Western Europe and Mediterranean Sea are mainly characterized by relatively low velocities, strongly contrasting with the fast roots of the Eastern European Craton. Many regional scale structures are also evident in the model, thus providing insights into the complex geodynamic framework of the European continent. Most prominent are the low-velocity West Mediterranean spreading basins and European Cenozoic rift system, and seismically fast features connected to subduction of Adria microplate, Hellenic Arc and Calabrian Arc. Radial anisotropy does not vary very significantly with respect to the PREM profile, as available data only resolve lateral variations to a limited degree due to trade-off with velocity. EPmantle has the potential to provide a reliable seismological reference for the upper-mantle structure in the broad European region.