A modelling comparison between received sound levels produced by a marine Vibroseis array and those from an airgun array for some typical seismic survey scenarios

Marine Vibroseis (MV) may provide a marine seismic sound source that has less environmental impact than conventional airguns. Modelled sound levels from a realistic MV array and airgun array with similar downward energy at frequencies <. 100. Hz were compared under three scenarios: shallow, deep, and slope. Changing the layout of the MV array's higher frequency sources reduced sound exposure levels (SELs) by 4. dB. At 100. m range this MV was 20. dB lower in peak-to-peak sound pressure level vs. the airgun array, decreasing to 12. dB lower at 5. km, the maximum modelled range for peak levels. SELs were less clear-cut, but for both shallow and deep water, MV produced 8. dB lower SELs than the airguns at 100. km range because of MV's reduced bandwidth. Overall, MV produced lower broadband SELs, especially at long range, and lower peak pressure, especially at short range, than airguns