The effects of bottom sediments on the measured spectrum of seismic airgun pulses as a function of range

Abstract

Sound from seismic airgun pulses is well known to be a measurable component of the marine soundscape even hundreds of kilometers from the source vessel. The peak frequency of the pulses is normally below 100 Hz, and hence the concern is often raised that the airguns may mask the communications of large baleen whales. Recently, there have been reports of significant energy from seismic airguns in the range of 1–10 kHz which could mask calls from a wider range of marine life. Measurements and modeling of a variety of deep water environments are compared to show that environments with very hard bottom types support the long-range propagation of frequencies above 500 Hz from seismic airgun arrays.