The Polish Ministry of Defense tells DR’s P4 Bornholm that a military exercise was carried out in Ustka, ten miles southeast of Bornholm at the time when the tremors were felt.
The data support the Swedish seismologist Björn Lund’s theory.
“What usually happens when we receive reports of rumbles and tremors is almost always that the air force has passed through the sound barrier at sea, and the atmospheric conditions have been such that the sonic boom rolled in over land,” he told TT two days after the mysterious tremors.
The Polish Ministry of Defense says nothing about whether the plane went through the sound barrier, but they used F16s that practiced hitting targets on land.