Imaging oceanic basins with wave equation and radiative transfer models

When seismic information is used to map Earth structures, a primary challenge is modelling the response of seismic wavefields to strong lateral variations in medium properties. These variations are especially relevant across oceanic basins with mixed continental-oceanic crust and including magmatic systems. These highly-scattering and absorption media produce stochastic signatures that are hard to separate from complex coherent reverberations due to shallow Moho. The discrimination between these two effects is fundamental for improving full-waveform techniques when imaging oceanic basins at regional and global scales. Here, we present a joint tomographic and modelling approach focusing on the ~1 Hz frequency band, where seismic scattering and attenuation mechanisms are predominantly resonant. Firstly, we image late-time coda attenuation as a marker of seismic absorption across the Italian peninsula and the Tyrrhenian Sea. Regional-scale data provide the ideal benchmark to explore the potential of attenuation imaging using radiative-transfer-derived sensitivity kernels in a mixed continental-oceanic crust. Then, we explore the response of seismic wavefield to structural variations combining coda-attenuation imaging with simulations based on radiative transfer and wave-equation modelling. The results provide evidence of intra-crustal reverberations and energy leakage in the mantle, finally being able to map Moho depths with regional earthquakes. This work is an ideal forward model of seismic wavefields recorded across the oceanic crust for future full-waveform inversions and imaging of crustal discontinuities.