Dedicated Ultra-High Resolution Seismic Diffraction Imaging for Boulder Detection: A Case Study from the Baltic Sea

The study presents an ultra-high resolution (UHR) seismic diffraction imaging method for detecting boulders in the Baltic Sea, where such boulders pose risks to offshore wind farm installations. Utilizing a beamforming approach as an alternative to traditional seismic reflection methods, the methodology involved custom-designed hydrophone arrays to record diffracted energy, enabling precise localization of subsurface objects. Results showed correlations with bathymetric data and anomalies related to cone penetration test (CPT) boreholes, demonstrating the method's effectiveness in identifying both surface features and subsurface disturbances. Through comprehensive data processing-incorporating denoising, reflection suppression, and beamforming algorithms-a semblance-weighted envelope of diffraction amplitudes 3D cube was generated, revealing significant anomalies. Overall, this method's ability to accurately identify both surface and subsurface objects highlights its robustness for broader applications in marine geophysics and resource management.