Abstract
Summary First-arrival traveltime and slope tomography uses traveltimes, source and receiver slopes of locally-coherent events to build high-resolution subsurface velocity models. These models can be further used as background/initial models for depth migration or full waveform inversion. However, complex tomography or bathymetry can cause numerical complications when discretization is performed on rectangular grids. To take into account complex known geometries in a versatile and accurate way, we calculate slopes and traveltimes of locally-coherent events with a finite-difference (FD) factored eikonal solver on curvilinear grid using a 2D surface-flattening scheme. Moreover, a matrix-free inverse problem is implemented with the adjoint-state method for the estimation of the data misfit gradient. This new formulation of slope tomography is extended to TTI acoustic media, where the model space is parameterized by four anisotropic parameters $(v_v,\epsilon,\delta,\theta)$. Preliminary synthetic tests with complex topography and surface acquisition validate the formulation of the method.
Published Version
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