Inverse scattering of surface waves: imaging of near-surface heterogeneities

Abstract

S U M M A R YAn efficient inverse scattering method is developed for imaging near-surface heterogeneities using scattered surface waves. Three dimensional elastodynamic wave propagation and scattering in a laterally invariant embedding medium is considered. The Born Approximation is used and the scattered wavefield is expressed as a domain type integral representation. The computation time of Green's tensor elements is reduced by considering the radial symmetry of the medium. The method is validated by numerical tests. Ultrasonic laboratory data obtained from a scale model experiment are used for imaging the near-surface inhomogeneities caused by an epoxy-filled hole in the surface of an aluminum block. Both synthetic and the scale model tests show that the location, the actual density contrast and the depth of the inhomogeneities are reasonably well estimated.

Estimating the Location of Scatterers by Seismic Interferometry of Scattered Surface Waves

“…To calculate the scattered wavefield, the computationally efficient method developed by Kaslilar (2007) is used. In this method three dimensional propagation and scattering of elastic waves are considered in an isotropic, laterally homogeneous embedding in which bounded objects with contrasting density are present.…”

“…where the source the receiver and scatterer locations, the angular frequency and the source waveform are denoted by For the modelling the parameters from the ultrasonic laboratory experimental set-up described in Kaslilar (2007) are used, since a laboratory experiment is planned for future studies. The geometry and the medium parameters of the model are given in Figure 1.…”

“…Several authors used scattered surface waves for imaging cavities, buried objects, or shallow water reservoirs (Snieder, 1987;Herman et al, 2000;Campman and Riyanti, 2007;Kaslilar and Herman, 2006;Kaslilar, 2007). The scattered surface waves are studied in detail in terms of seismic interferometry by Halliday and Curtis (2009).…”

“…The scattered wavefield is modeled using the integral representation of the scattered wavefield given in Kaslilar (2007). For selected virtual-source locations, the interferometric estimates of the ghost scattered wavefields are obtained.…”

Effects of Surface Scattering in Waveform Inversion

“…Xu and Wiens, 1997;Gu et al, 2005). Kaslilar (2007) and Campman and Riyanti (2007) use a superposition of small-scale heterogeneities on a laterally invariant embedding medium to invert scattered surface waves. In controlled source seismology the most popular forward solutions are finite difference frequency domain methods, mostly in a 2D viscoacoustic, isotropic implementation (e.g.…”