Amplitude Control In Shallow Seismic Surveying

The amplitude of seismic waves contains valuable information on sub-surface soil parameters. In order to extract this information from the seismic records we have to: 1) preserve seismic amplitudes during acquisition and subsequent (pre-) processing; 2) determine (preferably) absolute reflection strength-versus-offset distribution from the true amplitude data; 3) interpret reflection strength information in terms of sub-surface soil parameters. In this paper we deal with the implementation of amplitude-versus-offset analysis in shallow seismic exploration. We show that use of seismic amplitude information can be successful at the cost of extensive (quantitative) monitoring of, e.g., source-signature and geophoneresponse and compensation for any changes or differences observed. A method to determine absolute reflection strength as a function of offset followed by an estimation of soil parameters is presented. This method is based upon the interpretation of amplitude ratios in primary-multiple chains. Practical application of this method has been tested on several datasets, two of which are presented here.