Ambient‐Noise Tomography of the Ligurian‐Provence Basin Using the AlpArray Onshore‐Offshore Network: Insights for the Oceanic Domain Structure

Abstract

Efficient processing scheme to remove transients and reduce tilt and compliance from continuous ambient noise recorded by OBSs• Computation of iterative correlations between OBSs based on a virtual reconstruction of the Rayleigh waves• Thin, anomalous oceanic crust with gabbroic intrusions evidenced in the basin axis from a joint interpretation of V s and V p models

Ambient‐Noise Wave‐Equation Tomography of the Alps and Ligurian‐Provence Basin

“…We use a subset of the data used by Nouibat, Stehly, Paul, Schwartz, Bodin, et al (2022) and Nouibat, Stehly, Paul, Schwartz, Rolland, et al (2022) consisting of vertical component cross-correlations computed between 600 broadband stations from all available temporary and permanent networks in the Alpine region (Figures 1, during the period 2015-2019. The station array includes the entire AlpArray Seismic Network (AASN) and the Cifalps-2 experiment.…”

“…Several ambient noise tomography (ANT) were conducted in the region. Following on from the large-scale ANT by Lu et al (2018), which used a part of the land component of AlpArray, the recent ANT by Nouibat, Stehly, Paul, Schwartz, Bodin, et al (2022) and Nouibat, Stehly, Paul, Schwartz, Rolland, et al (2022) was the first study to use the entire AlpArray network, resulting in a land-sea model covering the Alps and Northwestern Mediterranean. These large-scale models, and other models focus on specific regions such as the western Alps (Kästle et al, 2018;Zhao et al, 2015Zhao et al, , 2020, the southeastern Alps (Sadeghi-Bagherabadi et al, 2021), the Vienna basin (Schippkus et al, 2020), the Bohemian massif (Kvapil et al, 2021), and the Ligurian sea (Magrini et al, 2022;Wolf et al, 2021), have substantially improved existing knowledge and have provided new insights into the complex deep structure of the region.…”

“…These large-scale models, and other models focus on specific regions such as the western Alps (Kästle et al, 2018;Zhao et al, 2015Zhao et al, , 2020, the southeastern Alps (Sadeghi-Bagherabadi et al, 2021), the Vienna basin (Schippkus et al, 2020), the Bohemian massif (Kvapil et al, 2021), and the Ligurian sea (Magrini et al, 2022;Wolf et al, 2021), have substantially improved existing knowledge and have provided new insights into the complex deep structure of the region. They highlighted Moho jumps beneath the external crystalline massifs (Lu et al, 2018;Nouibat, Stehly, Paul, Schwartz, Bodin, et al, 2022) and Moho dipping following the subduction of European continental crust in the southern Western Alps (Nouibat, Stehly, Paul, Schwartz, Bodin, et al, 2022;Zhao et al, 2015Zhao et al, , 2020, and provided clues about the lithological nature of the crust in the Ligurian basin (Nouibat, Stehly, Paul, Schwartz, Rolland, et al, 2022;Wolf et al, 2021).…”

“…At shorter periods, however, the effect of the water layer can no longer be neglected and the surface wave propagates as a Rayleigh-Scholte wave, which is a fluid-solid interface wave. Nouibat, Stehly, Paul, Schwartz, Rolland, et al (2022) have shown that a water layer thicker than 0.5 km can have a significant effect on the Rayleigh-Scholte wave dispersion at period ≤20 s and should therefore be taken into account in tomographic studies. Thus, several NOUIBAT ET AL.…”

“…Thus, several NOUIBAT ET AL. 10.1029/2023JB026776 5 of 28 studies have taken the water column into account when inverting the local dispersion curve of Ralyeigh-Scholte waves extracted from noise correlation into a local 1-D V s model (e.g., Carvalho et al, 2022;Guerin et al, 2020;Mordret et al, 2014;Nouibat, Stehly, Paul, Schwartz, Rolland, et al, 2022;Wolf et al, 2021). However, this assumes a strictly 1-D coupling in a laterally homogeneous medium.…”