An underwater pipeline burst cannot be caused by an explosion outside of the pipeline because the physical strength against compressive forces is too great.

Accelerated corrosion can result in steel being dissolved at a rate that can cause a new pipeline to leak in a few weeks after commissioning, and a shock wave within the pipeline would cause gas to explode out of the corroded weakness with a force sufficient to be detected by earthquake detectors.

The most probable cause of the failures of the Nord Stream pipelines is accidental (or intentional) weakness caused by accelerated corrosion from stray current to the Norway to Poland pipeline and an accidental (or intentional) pressure shock from the pigging operation by the Nord Stream pipeline operating company.