Full-waveform tomography of Sulawesi accounting for the effects of surface topography and the fluid ocean

We present a 3-D seismic structural model of the lithosphere and underlying mantle beneath Sulawesi obtained from full-waveform inversion (FWI), using seismic data filtered at periods from 12 - 150 s. We image isotropic P-wave velocity, radially anisotropic S-wave velocity and density via an iterative non-linear inversion that begins from SASSY21, a publicly available FWI model for Southeast Asia. The spectral-element solver Salvus is employed to compute the full 3-D wavefield through an anelastic Earth, accommodating effects of surface topography, bathymetry and the fluid ocean. Realistic surface topography and the fluid ocean are not routinely accounted for, mainly due to the requirement for advanced meshing techniques. Furthermore, replacing the volume of the ocean by acoustic elements to model it as a fluid medium requires solving a coupled system of the acoustic and the elastic wave equation, which is computationally more expensive. Here, we present initial results from investigating the effects of both surface topography and the fluid ocean on seismic waves.