f Tube-wave-VSP in cracked crystalline rocks: some new aspects

In vertical seismic profiling tube waves are generalty classified as noise, They have, however, one useful application: Tube waves can be generated by compressional waves at fluid filted cracks crossing the walt of the borehole. In this case the permeability of the crack can be estimated from the amplitude ratio of the incident p - wave and the generated tube wave.