Abstract
The 3D seismic enable a better understanding of phreatomagmatic activity that occurred at the Gjallar ridge in the Vøring basin, mid-Norway. Structures associated with this activity were imaged and a causality relationship was established. Those structures included hydrothermal vent complexes, sill complexes and faults. The Kai formation significantly affected by polygonal faulting that were likely to play as evacuation structures for the fluid migrating to the BPU.