f Experimental and finite difference modelling of borehole mach waves

In crosshole tomography, the radiation pattern of the source has a large influence on the observed wavefield. Meredith et al . (1991) showed how the Mach wave, generated by the tube wave in a soft formation when its velocity is high than the shear wave velocity, can produce a large arrival in the receiver borehole and hide the direct shear wave arrival. In this paper we studied the problem of seismic source radiation from a borehole into a soft formation using laboratory scaled borehole models and the finite differente method.