Seismic waveforms from explosive sources located in boreholes and initiated in different directions

A study of the effect of explosive source orientation in a borehole on the nature of emanating seismic waves was made. High frequency triaxial accelerometers mounted on the surface and in boreholes in underground mines were the diagnostic sensors. A variety of explosive sources initiated with the detonation reaction propagating towards the detector and away from the detector were studied in highly competent rock. The results show significant differences in both the amplitude and the frequency spectra of the signal for the two modes. The respective azimuthal distribution of P and S wave amplitudes from propagating linear sources are also found to be at variance with those predicted by existing theoretical approaches.

► The nature of seismic waves from explosive sources in boreholes has been studied. ► Seismicity is measured by high-frequency high-amplitude triaxial accelerometers. ► Amplitude and frequency of blast seismic waves are dependent on initiation mode. ► Measured direct/reverse ratio of PPV is greater than 4 in 3 and 6 m explosive columns. ► Contribution of charges along explosive column conditions the shape of seismic waves.