Abstract. The Liguro-Provençal basin was formed as a back-arc basin of the retreating Calabrian-Apennines subduction zone during the Oligocene and Miocene. The resulting rotation of the Corsica-Sardinia block is associated with rifting, shaping the Ligurian Sea. It is still debated whether oceanic or atypical oceanic crust was formed or if the crust is continental and experienced extreme thinning during the opening of the basin. We invert velocity models using an amphibious network of seismic stations, including 22 broadband Ocean Bottom Seismometers (OBS) to investigate the lithospheric structure of the Ligurian sea. The instruments were installed in the Ligurian Sea for eight months between June 2017 and February 2018 as part of the AlpArray seismic network. Because of additional noise sources in the ocean, OBS data are rarely used for ambient noise studies. However, we attentively pre-process the data, including corrections for instrument tilt and seafloor compliance. We took extra care to exclude higher modes of the ambient-noise Rayleigh waves. We calculate daily cross-correlation functions for the LOBSTER array and surrounding land stations. Additionally, we correlate short time windows that include teleseismic earthquakes that allow us to derive surface wave group velocities for longer periods than using ambient noise only. Group velocity maps are obtained by inverting Green’s functions derived from the cross-correlation of ambient noise and teleseismic events, respectively. We then used the resulting 3D group velocity information to calculate 1D depth inversions for S-wave velocities. The shear-wave velocity results show a deepening of the Moho from 12 km at the southwestern basin centre to 20–25 km at the Ligurian coast in the northeast and over 30 km at the Provençal coast. We find no hint on mantle serpentinisation and no evidence for an Alpine slab, at least down to depths of 25 km. However, we see a separation of the southwestern and northeastern Ligurian Basin that coincides with the promoted prolongation of the Alpine front.

中文翻译：

---

使用海底地震仪数据通过环境噪声层析成像技术揭示利古里亚海的3D地壳结构

摘要。渐新世和中新世期间，里古罗-普罗旺斯盆地形成为后退的卡拉布里亚-亚平宁山脉俯冲带的后弧盆地。科西嘉-撒丁岛区块的最终旋转与裂谷有关，塑造了利古里亚海。是否形成大洋的或非典型的洋壳还是在盆地开放期间地壳是大陆性的并且经历了极度的稀薄还存在争议。我们使用包括22个宽带海底地震仪（OBS）的两栖地震台网对速度模型进行反演，以研究利古里亚海的岩石圈结构。作为AlpArray地震网络的一部分，这些仪器于2017年6月至2018年2月在利古里亚海安装了八个月。由于海洋中有其他噪声源，OBS数据很少用于环境噪声研究。但是，我们会认真处理数据，包括对仪器倾斜度和海底柔度进行校正。我们格外小心，以排除较高模式的环境噪声瑞利波。我们计算LOBSTER阵列和周围陆地站的每日互相关函数。此外，我们将包括远程地震在内的短时窗关联起来，这使我们能够比仅使用环境噪声更长的时间来推导面波群速度。通过分别逆转由环境噪声和地震事件的互相关推导的格林函数获得群速度图。然后，我们使用所得的3D组速度信息来计算S波速度的1D深度反演。剪切波速度的结果表明，莫霍面从西南盆地中心的12 km增深到东北的利古里亚海岸的20–25 km，而在普罗旺斯海岸则超过30 km。我们没有发现地幔蛇形化的迹象，也没有证据表明至少在25 km的深度上有一块高山板。但是，我们看到西南利古里亚盆地和东北利古里亚盆地分离，这与阿尔卑斯山锋线的延长延长相吻合。