Development of a sound propagation model to monitor seismic survey noise in Irish waters

Following Irelands 2015 Atlantic Margin Oil and Gas Exploration Licensing Round, the Porcupine Basin continues to be a significant site for seismic exploration activities to investigate sub-bottom structure. Recent literature has reported on the environmental implications of marine seismic surveys, highlighting alarmed and avoidance behaviour in several marine mammal species as a common response to air gun signals. Underwater acoustic monitoring and mapping has been targeted as a research priority under the EUs Marine Strategy Framework Directive. The findings will be essential for designing and implementing appropriate regulation regarding underwater noise. In this study, a modelling method which employs the Parabolic Equation technique (RAMGeo) was used to model the transmission loss (TL) of low frequency noise across real, range-dependent 2D source-to-receiver sections from the Porcupine Basin. The TL values computed in the model were measured against their corresponding observed values, which were recorded during a research cruise in July 2014, to coincide with 3D seismic operations in the area at locations across the Basin. Different sets of geoacoustic parameters were tested as through RAMGeo and evaluated for their predictive power. Porcupine Basin Model C, performed best, predicting SEL for a single pulse to within 6dB for all six locations considered