Upper-mantle structure of the Baltic Shield below the Swedish National Seismological Network (SNSN) resolved by teleseismic tomography
Upper-mantle structure of the Baltic Shield below the Swedish National Seismological Network (SNSN) resolved by teleseismic tomography
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通过远震层析成像解析瑞典国家地震台网（SNSN）下方波罗的海地盾的上地幔结构
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发表时间：
2007
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通讯作者：
R. Bödvarsson
中科院分区：
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作者：
T. Eken;Z. Shomali;Z. Shomali;R. Roberts;R. Bödvarsson
利用非线性高分辨率远震p相层析成像技术研究了波罗的海地盾下的上地幔结构。对瑞典国家地震网（SNSN）记录的52次远震观测的相对到达时间残差进行反演，以描绘上地幔的结构。该网络由47个（目前正在工作）三分量宽带站组成，位于约450公里宽和1450公里长的区域。为了减少由于地球结构可能具有显著的三维性而导致的复杂性，本研究选择的事件与阵列的长轴（±30◦）接近。结果表明，纵波速度扰动为±3%，至少在网络以下470公里处。该阵列的尺寸允许在更深的深度进行结构反演，并且可以解决深度达680公里的横向速度变化。在阵列的中心部分（60◦- 64◦N）下方，射线覆盖最好的地方，数据显示在大约300公里深处有一个相对较低速度的大区域。在深度小于250 - 300公里处，模型包含了许多特征，包括一个明显的向北倾斜的板状结构。
SUMMARY Upper-mantle structure under the Baltic Shield is studied using non-linear high resolution teleseismic P-phase tomography. Observed relative arrival-time residuals from 52 teleseismic earthquakes recorded by the Swedish National Seismological Network (SNSN) are inverted to delineate the structure of the upper mantle. The network consists of 47 (currently working) three-component broad-band stations located in an area about 450 km wide and 1450 km long. In order to reduce complications due to possible significant three-dimensionality of Earth structure, events chosen for this study lay close to in-line with the long-axis of the array (±30 ◦ ). Results indicate P-wave velocity perturbations of ±3 per cent down to at least 470 km below the network. The size of the array allows inversion for structures even at greater depths, and lateral variations of velocity at depths of up to 680 km appear to be resolved. Below the central part of the array (60 ◦ ‐64 ◦ N), where ray coverage is best, the data reveals a large region of relatively low velocity at depths of over about 300 km. At depths less than about 250‐ 300 km, the models include a number of features, including an apparent slab-like structure dipping gently towards the north.