We conducted detailed numerical modelling of sound propagation at two locations within the survey area. At each location, the full sound spectrum from the seismic array (5085 cubic inches) was simulated to provide potential impact radii.
We used our validated underwater sound propagation model, UnaCorda, to predict the acoustic propagation characteristics of the towed seismic array. Information and data from specialist industry software, scientific literature, industry publications, global ocean models, national guidelines and site specific geophysical / geotechnical data were used to provide data to the model in order to provide a realistic and site specific assessment.
The UnaCorda model incorporated different movement variables for receptor species to accurately predict the sounds levels reaching target species, depending on whether the individuals were either stationary (worst case scenario under the precautionary principle) or fleeing (expected response for marine mammals).
We interpreted the results of the combined modelling using established scientific acoustic thresholds to determine the impact radii for lethal and non-lethal effects on marine mammal, turtle and fish species.