SUMMARY

This research provides new constraints on the intermediate depth upper-mantle structure of the Hellenic lithosphere using a three-step Rayleigh-wave tomography. Broadband waveforms of about 1000 teleseismic events, recorded by ∼200 permanent broad-band stations between 2010 and 2018 were acquired and processed. Through a multichannel cross-correlation technique, the fundamental mode Rayleigh-wave phase-velocity dispersion curves in the period range 30–90 s were derived. The phase-velocities were inverted and a 3-D shear velocity model was obtained down to the depth of 140 km. The applied method has provided 3-D constraints on large-scale characteristics of the lithosphere and the upper mantle of the Hellenic region. Highlighted resolved features include the continental and oceanic subducting slabs in the region, the result of convergence between Adria and Africa plates with the Aegean. The boundary between the oceanic and continental subduction is suggested to exist along a trench-perpendicular line that connects NW Peloponnese with N. Euboea, bridging the Hellenic Trench with the North Aegean Trough. No clear evidence for trench-perpendicular vertical slab tearing was resolved along the western part of Hellenic Subduction Zone; however, subcrustal seismicity observed along the inferred continental–oceanic subduction boundary indicates that such an implication should not be excluded. The 3-D shear velocity model supports an N–S vertical slab tear beneath SW Anatolia that justifies deepening, increase of dip and change of dip direction of the Wadati-Benioff Zone. Low velocities found at depths <50 km beneath the island and the backarc, interrelated with recent/remnant volcanism in the Aegean and W. Anatolia, are explained by convection from a shallow asthenosphere.

中文翻译：

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远震瑞利波层析成像对希腊岩石圈的深层结构

概要

这项研究使用三步瑞利波层析成像技术对希腊岩石圈的中间深度上地幔结构提供了新的限制。采集并处理了2010年至2018年之间约200个永久性宽带站记录的约1000次地震事件的宽带波形。通过多通道互相关技术，得出了周期范围为30-90 s的基模瑞利波相速度色散曲线。倒转相速度，并获得一个深度为140 km的3-D剪切速度模型。该应用方法对岩石圈和希腊地区上地幔的大规模特征提供了3-D约束。突出的解析特征包括该地区的大陆和海洋俯冲平板，爱德里亚与非洲板块之间融合的结果。海洋和大陆俯冲之间的边界被认为沿着一条沟渠垂直线存在，该沟渠将伯罗奔尼撒西北部与尤博亚猪笼草连接起来，将希腊海沟与北爱琴海槽连接起来。在希腊俯冲带的西部没有明确的沟渠垂直板撕裂的证据。然而，沿推断的大陆-海洋俯冲边界观察到的亚壳地震活动表明，不应排除这种影响。3-D剪切速度模型支持西南安纳托利亚下的N–S垂直板状裂缝，这证明了Wadati-Benioff区的加深，倾角增大和倾角方向变化。在小岛和后方弧面以下<50 km处发现低速，