The principle of seismic reciprocity

The classical principle of seismic reciprocity (PSR) is considered. Systems of observations for experimental PSR verification are presented. Model stu dies and in situ experiments with solitary pulsed signals showed that PSR h olds true to a high degree of accuracy. The PSR validity could not be demon strated in the case of simultaneous propagation of pulsed and harmonic sign als in the medium and in the case of vibratory signals at a source-receiver distance of about 300 m.