Seismic exploration of the sea floor using fin whale songs and seismic airguns in the Bransfield Strait, Antarctica

Abstract

The use of seismic airguns has an environmental impact that is especially intense in relation to marine mammals. As a result, new techniques are being explored to replace or complement this tool. In this study, we test our ability to obtain seismic information about the shallow seafloor structure using fin whale songs as an alternative seismic source. We analyse data collected by ocean-bottom seismometers deployed around Orca volcano in the Bransfield Strait, Antarctica, in 2019. We detected fin whale calls and designed an algorithm to calculate their locations and origin times. We used a relative approach to reduce location uncertainty based on the similarity of waveforms between consecutive calls. We were able to calculate the trajectory of a fin whale that crossed over Orca volcano. Strikingly, the whale path coincided partially with a multi-channel seismic profile carried out with airgun shots. This coincidence allowed us to investigate the performance of the whale calls as seismic sources, comparing them to the almost co-located airgun profile. We constructed receiver gathers using both whale calls and airgun shots. The main features of the whale call sections are consistent with the results obtained using the airgun source. We conclude that although this method has some drawbacks, such as the unpredictable behaviour of whales and the smaller power and lower resolution capabilities of the whale calls compared to the airgun surveys, it is still a feasible alternative as a complement for active-source seismic studies in the marine environment.