“Mystery Tremors on Bornholm Island Puzzle Scientists and Authorities”

At first, it was believed that the tremors on Saturday were caused by earthquakes. Seismologists then theorized that they were caused by controlled explosions in Poland, more than 140 km to the south.

On Monday, the Geological Survey of Denmark and Greenland (Geus) announced that the tremors “were not caused by earthquakes, but by pressure waves generated in the atmosphere”. However, they came from an “unknown source”. Geuss said in a statement that the seismic activity had a magnitude of 2.3.

“Seismologists report that it is unlikely that the earthquakes were caused by a controlled explosion in Poland, which was carried out shortly before the first reports of an earthquake in Bornholm,” Geus representatives said.

On Saturday, Geus said he had received more than 60 reports from local residents of “earthquake-like tremors”, described as a deep rumbling, shaking and rattling as pressure changes in the ear.

The local Police stated that no one was injured as a result of the unexplained “waves”. Danish media reported that the “wave” was caused by a crack in the wall of a house.

Polish authorities said the Anaconda 23 exercise in Ustka, northern Poland, involved jet fighters and artillery.

Home to nearly 40,000 people, Bornholm is a rocky island in the Baltic Sea, south of Sweden, northeast of Germany and north of Poland.