Author(s)

I.-K. Fontara, S. L. Parvanova, P. S. Dineva, T. Rangelov, F. Wuttke

Abstract

Two-dimensional mechanical models consisting of discrete and continuous systems, accompanied with different boundary integral equation (BIE) techniques, are used for the synthesis of seismograms in a laterally inhomogeneous geological profile situated in a half-plane which mechanical properties vary with respect to the depth. Seismic load is time-harmonic, presented by incident SH-wave or wave radiating from an embedded line seismic source. The material inhomogeneity is modelled in two different ways: (i) as a continuous model where material properties are quadratic functions of depth; (ii) as a discrete model where material properties vary in a discrete way and the geological profile is presented by a stack of flat horizontal layers. The computational tools are based on the BIEM using: (i) analytically derived Green’s function for a quadratically inhomogeneous in depth half-plane; (ii) a hybrid (wave number integration method) WNIM-BIEM; or (iii) direct displacement BIEM based on the elastodynamic fundamental solution for the full plane. A validation study is presented. All simulations reveal the sensitivity of the synthetic seismic signals on the type and characteristics of the seismic load, on the wave path inhomogeneity and on the geotechnical properties of the local geological region as sub- and free- surface relief and material gradient with respect to the depth.

Keywords

SH-wave, relief, Green’s function for inhomogeneous half-plane, BIEM, synthetic seismograms