Marine seismic vibrators reduce risk to marine mammals for underwater oil and gas exploration

Commonly used in underwater oil and gas exploration, cylinders of compressed air, called airguns, pose risks for marine life due to the broad-frequency underwater noise they emit. Marine seismic vibrators, called vibroseis, have shown promise to reduce these risks by using lower amplitude sounds with limited bandwidths at very low frequencies. New work looks to assess their impact on wildlife in a real-world scenario.

Austin et al. analyzed the potential effects of marine vibroseis on marine mammals in a shallow, near-shore region of Cook Inlet, Alaska. The pilot study examined the first commercial use of underwater seismic vibroseis, measuring a low-frequency sweep signal between 1.5 and 16 hertz and a higher-frequency sweep at 8 to 96 hertz.

The work provides several different criteria for assessing potential acoustic effects to aid regulators and stakeholders, said author Melanie Austin.

“Prior to this study there was no information available about the source level for the marine vibroseis source, the full frequency distribution of the noise, or of the ranges from the source where marine mammals could be affected by the noise,” she said.

Use of the marine vibroseis source in near-shore shallow water is unlikely to cause auditory injury to marine mammals but has the potential to cause behavioral disturbance at distances between 10 meters and 2.4 kilometers, depending which impact assessment criteria are applied.

Consistency of the measurements forward/aft and broadside to the source indicated that the source has weak horizontal directivity and exceeded standard National Marine Fisheries Service sound level thresholds for behavioral disturbance at maximum distances of 1.3 kilometers for the low-frequency sweep and 2.4 kilometers for the higher-frequency sweep. The study shows that these thresholds likely result in an overestimation of the distance to effect.

The group next looks to study the acoustic presence and absence of marine mammals in the study area before, during and after the survey.

Source: “Sound characterization and marine mammal impact assessment of a marine vibroseis source in a shallow, near-shore environment,” by Melanie Austin, Daniel Yancey, Jennifer Dushane, and Manuel Castellote, The Journal of the Acoustical Society of America (2026). The article can be accessed at https://doi.org/10.1121/10.0043144 .