Vibration and air pressure monitoring of seismic sources

Alejandro David Alcudia León, Robert R. Stewart, Nanna Eliuk, Rick Espersen

Vibration monitoring of a seismic exploration program was conducted in the Nanton area, Alberta. Peak particle velocity (PPV) in three directions and peak air-overpressure (PSPL) were recorded by a vibration monitoring system. Dynamite blast monitoring suggested no damage could be caused to the water spring with a 1.6 km safe radius, since the recorded PPV indicated ground vibrations well below permissible levels and comparable to natural vibrations. The vertical and longitudinal channels both yielded PPV values of 0.0476 mm/s whereas the transverse channel yielded 0.0635 mm/s for a series of dynamite shots. The computed peak vector sum (PVS) was 0.0794 mm/s, which is smaller than the PVS obtained from natural vibrations monitoring (i.e., 0.0953 mm/s). Vibration monitoring results suggest that 3C measurements are required because the maximum ground motion could occur in any direction. Waveform analysis of ground motion and air vibration may reveal some interesting features in the data. For instance, the existence of harmonics in the recorded signals demonstrates that the transfer of energy from the vibrator to the earth is not perfect. Further analysis of the frequency harmonics may give additional information about the source-generated noise.