ABSTRACT
In this chapter the term ‘Q’ used in the title in the classic paper of Knopoff, 1964 will be distinguished from the engineering rock mass quality Q-value of Barton et al., 1974, by reference to the seismic quality as ‘seismic Q’, Qseis, or Qp or Qs if the compressional wave or shear wave components have been distinguished. In fact, as we shall see, there are obvious connections between Qseis and the rock quality Q-value; a heavily jointed clay-bearing rock mass with low Q-value (probably less than 0.1) will inevitably cause great attenuation and have a correspondingly low Qseis (perhaps less than 5), while an almost unjointed massive rock mass with very high Q-value (e.g. 100-500) will inevitably cause little attenuation and have correspondingly high Qseis, depending on whether shallow or at great depth.
