Rayleigh waves are well known to attenuate due scattering when they propagate over a rough surface. Theoretical investigations have derived analytical expressions linking the attenuation coefficient statistical surface roughness parameters, namely, surface's root mean squared height and correlation length wave's wavenumber. In literature, three regimes been identified—the geometric (short wavel...

In boreholes where formation shear velocity is lower than borehole tluid velocity neither refracted shear waves nor pseudo-Rayleigh waves can propagate. When frequency response of the sonde does not extend to low frequencies (e.g. 2 kHz) Stoneley waves are not excited efficiently. In such cases refracted P, leaking modes (PL) and tluid waves become dominant phases on a full waveform acoustic lo...

In this paper, we are interested with the spectral study of an operator given by an elastic topographical waveguide, a deformed half-space, of which the cross-section is a local perturbation of a homogeneous half-plane. We look for guided waves propagating more rapidly than Rayleigh waves (which mathematically would correspond to embedded eigenvalues) and prove that there are no guided waves pr...

INTRODUCTION IN 1953, through cooperation of the Bernard Price Geophysical Institute of the University of the Witwatersrand and the University of Natal, a Columbia University-type long-period seismometer (To = 15 sec., Tg = 75 sec.) was installed in the seismological observatory of the University of Natal at Pietermaritzburg, Union of South Africa. This instrument was well situated for receivin...