Abstract
Concerns about the potential environmental impacts of geophysical surveys using air gun sources, coupled with advances in geophysical surveying technology and data processing, are driving research and development of commercially viable alternative technologies such as marine vibroseis (MV). MV systems produce controllable acoustic signals through volume displacement of water using a vibrating plate or shell. MV sources generally produce lower acoustic pressure and reduced bandwidth (spectral content) compared to air gun sources, but to be effective sources for geophysical surveys they typically produce longer duration signals with short inter-signal periods. Few studies have evaluated the potential effects of MV system use on marine fauna. In this desktop study, potential acoustic exposure of marine mammals was estimated for MV and air gun arrays by modeling the source signal, sound propagation, and animal movement in representative survey scenarios. In the scenarios, few marine mammals could be expected to be exposed to potentially injurious sound levels for either source type, but fewer were predicted for MV arrays than air gun arrays. The estimated number of marine mammals exposed to sound levels associated with behavioral disturbance depended on the selection of evaluation criteria. More behavioral disturbance was predicted for MV arrays compared to air gun arrays using a single threshold sound pressure level (SPL), while the opposite result was found when using frequency-weighted sound fields and a multiple-step, probabilistic, threshold function.
Highlights
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.license.Compressed air sources, commonly referred to as seismic air guns, are the most common marine geophysical survey sound source for oil and gas exploration [1] and are used for construction siting and studying subsea geomorphology
The received signal characteristics were compared to highlight the differences between the air gun array impulsive sounds and the Marine vibroseis (MV) array non-impulsive sounds
The PK, Sound exposure level (SEL), duration of the signal, and duty cycle were calculated as the maximum broadband (4 Hz to 25 kHz) value over all modeled depths
Summary
Compressed air sources, commonly referred to as seismic air guns, are the most common marine geophysical survey sound source for oil and gas exploration [1] and are used for construction siting and studying subsea geomorphology. Substantial technological and geophysical data processing advancements, combined with concerns about potential effects of seismic air gun sources on marine fauna, are driving a resurgence in research and commercial development of alternate technologies. Marine vibroseis (MV) systems produce controllable acoustic signals through volume displacement of water using a vibrating plate or shell that, unlike air guns, produce broadband acoustic signals when an ejected air bubble collapses in water. To obtain enough return of acoustic energy for seismic data processing, MV signals are typically longer waveforms with shorter inter-signal intervals than air guns
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
