Abstract. There are still open questions about the deep structure beneath the Western Alps. Seismic velocity tomographies show the European slab subducting beneath the Adria plate, but all these images did not clarify completely about the possible presence of tears, slab windows or detachments. Seismic anisotropy, addressed as an indicator of mantle deformation and studied using data recorded by dense networks, may shed some light about the location and orientation of mantle flow at depth. Using the large amount of shear wave splitting and splitting intensity measurements available in the Western Alps, collected through the CIFALPS2 temporary seismic network, together with already available data, highlight some new patterns, filling the gaps left by previous studies. Instead of the typical seismic anisotropy pattern parallel to the entire arc of the Western Alps, this study supports the presence of a differential contribution along the belt, only partly related to the European slab retreat. A nearly NS anisotropy pattern beneath the external Alps, direction that cuts the morphological features of the belt, is clearly found with the new CIFALPS2 measurements. It is however confirmed that the asthenospheric flow from Central France toward the Tyrrhenian Sea, is turning around the southern tip of the European slab.

中文翻译：

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使用 CIFALPS2 数据通过地震各向异性强调西阿尔卑斯山下方的地幔变形

摘要。关于西阿尔卑斯山下方的深层结构仍然存在悬而未决的问题。地震速度断层扫描显示欧洲板片俯冲到亚德里亚板块下方，但所有这些图像都没有完全阐明可能存在的撕裂、板片窗或脱离。地震各向异性作为地幔变形的指标，并使用致密网络记录的数据进行研究，可能有助于揭示地幔流在深处的位置和方向。利用通过 CIFALPS2 临时地震台网收集的西阿尔卑斯山可用的大量剪切波分裂和分裂强度测量值以及现有数据，突出了一些新模式，填补了先前研究留下的空白。这项研究并不支持平行于西阿尔卑斯山整个弧线的典型地震各向异性模式，而是支持沿该带存在差异贡献，仅部分与欧洲板片后退有关。新的 CIFALPS2 测量结果清楚地发现了外部阿尔卑斯山下方的近 NS 各向异性模式，即切割带形态特征的方向。然而，已证实从法国中部流向第勒尼安海的软流圈流正在绕欧洲板片的南端转向。