Influence of the Contribution of Body Waves to the Result of the Microseismic Sounding Method

The article presents a numerical study of the formation of the amplitude response in a free surface from simultaneous scattering of Rayleigh waves and vertically incident longitudinal waves by an embedded contrast velocity inclusion. It has been established that the significant presence of body waves in a microseismic field does not fundamentally change the result of the microseismic sounding method, which is based on the notion of the overwhelming contribution of the fundamental mode of a Rayleigh wave to the formation of the Earth’s microseismic field. Cases are considered when a microseismic signal at the same frequency is modeled only by the fundamental mode of the Rayleigh wave, only by a vertically incident longitudinal wave, and by both types of waves simultaneously. Variants of inhomogeneities with different dimensions and velocity properties are considered. The analysis was performed in a (λ, r)-space, in analogy with reconstruction of the structure of the geological setting in the microseismic sounding method, where λ is the wavelength of the fundamental Rayleigh mode and r is the coordinate on the Earth’s surface.