Surface Wavefield Tomography of the Alpine Region to Constrain Slab Geometries, Lithospheric Deformation and Asthenospheric Flow

面波非常适合于约束岩石圈和软流圈的各向同性和各向异性弹性性质。阿尔卑斯山地区的特点是相对较小的构造变化。要回答有关其岩石圈动力学的关键问题，需要特别高的成像分辨率。这种分辨率可以由波场层析成像提供，能够从由大口径、密集阵列记录的数据中提取高度完整的结构信息。将分析阿尔普阵列地震网络的记录，包括其海洋部分，以及C和D带(A、B、C、D)的记录，以成像远震瑞利波和乐夫波的局部传播以及横向分辨率低于50公里的地壳和地幔结构。由此得到的地球上方300公里的剪切波速度模型将成像俯冲的亚得里亚海和欧亚地幔岩石圈以及前陆。它将解决极性转换区域(阿尔卑斯山脉西南部到亚平宁山脉，阿尔卑斯山西部到阿尔卑斯山东部)，板片空隙(阿尔卑斯山中部)，板片断裂带(西南部阿尔卑斯山)，以及从东部阿尔卑斯山向迪纳里德山脉过渡(RT1，Reorg)的板块几何问题。岩石圈)。转换成密度异常将使我们能够估计阿尔卑斯山地区的板条拉力和浮力，并量化内生力对地表隆起和下沉的贡献(RT2，地表响应)。地震各向异性揭示了岩石圈最近和过去变形的印记以及软流圈中的地幔流动。我们将计算岩石圈和软流圈内地震各向异性的三维模型，为地壳变形、地壳和地幔之间以及板块运动和地幔流动之间的耦合/去耦合(RT3，Deform)提供新的证据。地壳地幔)。它还将进一步作为观测证据，通过数值模拟评估不同进化情景(RT1，REORG)的预测。新方法的开发将侧重于瑞利和勒夫相位和幅度的测量，以及它们在波场和阵列足迹下地震速度结构的曲率、幅度变化和累积性成像中的应用。为了处理大量的记录，自动化测量方法将被开发出来。Helmholtz和eikonal层析成像将扩展到各向异性情况。阿尔卑斯山地区的径向和方位各向异性剪切波速度模型的相速度图将被反演，嵌入到区域模型中并受地壳先验知识的约束。将开发基于不连续伽辽金方法的工具，对远震面波与阿尔卑斯山深层结构的相互作用进行有效的数值正演模拟。这些方法将允许对阿尔卑斯山及其前缘地区进行高分辨率和全区域尺度的成像。

Surface waves are ideally suited to constrain isotropic and anisotropic elastic properties of the lithosphere and asthenosphere. The Alpine region is characterized by relatively small-scale structural variations. To answer key questions regarding its lithospheric dynamics requires particularly high imaging resolution. Such resolution can be provided by the wavefield tomography, able to extract highly complete structural information from data recorded by a large-aperture, dense array. Recordings of the AlpArray Seismic Network, including its marine part, and of the Swaths C and D (AF A, B, C, D) will be analyzed to image both the local propagation of teleseismic Rayleigh and Love waves and crustal and mantle structure, with a lateral resolution below 50 km. The resulting shear-wave velocity model for the Earths upper 300 km will image the subducting Adriatic and Eurasian mantle lithospheres, as well as the forelands. It will resolve the slab geometry in the regions of polarity switches (SW Alps to Apennines, western to eastern Alps), of slab gaps (central Alps), of slab break-off (SW Alps), and in the transition from the eastern Alps towards the Dinarides (RT1, Reorg. of Lithosphere). Conversion into density anomalies will enable us to estimate slab-pull and buoyancy forces in the Alpine region and quantify the contribution of endogenous forces to surface uplift and subsidence (RT2, Surface Response). Seismic anisotropy reveals imprints of recent and past deformation on the lithosphere as well as mantle flow in the asthenosphere. We will compute a 3D model of seismic anisotropy within the lithosphere and the asthenosphere, offering new evidence on the deformation of the crust and on the coupling/decoupling between the curst and mantle and between plate motion and mantle flow (RT3, Deform. of Crust + Mantle). It will further serve as observational evidence to evaluate predictions by numerical modelling for different evolution scenarios (RT1, Reorg. of Lithosphere).New method development will focus on the measurement of Rayleigh and Love phases and amplitudes and their use in the imaging of the curvature, amplitude variations, and direcionality of the wavefields and of the seismic velocity structure beneath the arrays footprint. In order to cope with the large amount of recordings, automated measurement methods will be developed. Helmholtz and eikonal tomography will be extended to the anisotropic case. Phase velocity maps will be inverted for a radially and azimuthally anisotropic shear-wave velocity model of the Alpine region embedded into regional models and constrained by a-priori knowledge on the crust. Tools for efficient numerical forward modelling of the interaction of teleseismic surface waves with the deep structure of the Alps based on discontinuous Galerkin methods will be developed. The methods will allow the imaging of the Alps and their forelands that is both high-resolution and whole-region-scale.