Fig. 5: Ambient noise differential adjoint tomography.

A Differential time measurements for a typical station triplet: one virtual source (1) and a pair of receivers (2, 3). B Geometry for the forward simulation: one virtual source (red) and a subarray (blue). C Noise source intensity distribution versus azimuth for the synthetic noise interferometry data. D Inverted velocity based on interferometric differential time kernel. E Estimated velocity based on point source differential time kernel.