Scattering and attenuation of elastic wave by a viscoelastic cylinder

Abstract

Scattered S-wave The scattering and attenuation of a circular elastic cylinder with and without intrinsic attenuation caused by a normally incident plane compressional wave (P-wave) are investigated. The analytical solution of scattered field is derived in a convenient form. the synthetic seismograms for the scattered compressional wave, scattered shear wave, and total field are calculated for both a non-absorbing and an absorbing cylinder. Results show that scattering fields are the superposition of geometrical transmitted waves and which go through the cylinder and creeping (diffraction) waves and which propagate along the elastic-cylinder interface. The creeping waves shed radiation energy away tangentially at each point along their paths and are basicly not affected by the cylinder absorbing property. The first arrivals within shadow zone are creeping wave for low velocity inclusion and transmitted wave for high velocity inclusion. The phase match between the creeping waves and incident wave can cause resonance scattering resulting in the oscillation of the scattering cross-section. These effects have important influence on travel-time and Q tomographies.