Multiple suppression on a polar shelf - a case study in the Weddell Sea, Antarctica
During the past decade, the Antarctic continental shelf has been the subject of intensive seismic investigations with regard to its glacial history. In most marine seismic data from this area, high amplitude multiple reflections are a major problem. They are generated at the water bottom (a particularly high impedance interface) and account for a large fraction or even the majority of the recorded amplitude. Unusually well-compacted and flat-lying sediments in the near-surface give rise to a high seismic reflection coefficient at the seafloor. This overcompaction of the polar shelf sediments is evident from the high seismic velocities ranging from 2.0 to 2.6 km/s in the upper 150 m of the subsurface and is due to former ice load. At least since Eocene times, repeated glacial cooling has resulted in episodic expansions of the Antarctic ice sheet, and large grounded ice bodies have covered the Antarctic shelf out to the shelf edge during glacial periods.