A computer-implemented method includes providing a first velocity model obtained from a vertical seismic profile survey representative of an upper region of a subterranean formation. Wavefields from the first velocity model are datumed using wave equations to a datum line between the upper region and a target area beneath the upper region to obtain datumed wavefields. The method further includes obtaining interferometric common shot data and interferometric common midpoint data from the datumed wavefield using wave equations at the datum line. The first velocity model, the datumed wavefield, wavefield equations, and the interferometric common midpoint data are then used to generate a second velocity model representative of velocities in the target area.