On Saturday, May 13, a series of earthquakes, described as mysterious, occurred on the Danish island of Bornholm, located in the Baltic Sea, and is inhabited by 40,000 people.
Seismologists hypothesized that it originated from controlled explosions in Poland, more than 140 kilometers to the south, and from “acoustic pressure waves from an unknown source”.
The Geological Survey of Denmark and Greenland (GEOS), an official body that monitors the underground, came out to say that the tremors “were not caused by earthquakes, but by pressure waves from an event in the atmosphere”, but that they came from “an unknown source”.
Geos said: It had measured seismic tremors of 2.3 on the Richter scale, and had received more than 60 reports from citizens in Bornholm.
Distinguish between earthquakes and eruptions
Dr. Najeeb Abu Karaki, professor of geophysics and seismology at the University of Jordan, said in a statement to “Sky News Arabia”:
- In the absence of recordings, scientists may not be able to provide a completely reliable explanation.
- What they call sound pressure waves are probably the sounds of explosions that may be produced and sometimes recorded in seismic stations in the appropriate nearby areas, as a result of aircraft breaking the sound barrier.
- Seismic waves resulting from earthquakes are in the form of a succession of pressure waves, then disturbance or tension, while explosions in general, whether chemical, nuclear or otherwise, are recorded in the form of pressure waves in all directions, and this is one of the means of distinguishing between recorded waves resulting from explosions and those resulting from natural earthquakes.
- In any case, definitive distinction between explosions and earthquakes requires the recording of information from several seismic stations surrounding the location of the event.
frequent cases
Such tremors in Denmark have been repeated in the past, and often raise controversy every time about their causes, according to Abu Karaki, and examples of this include:
– In August 2016, areas in Amman were subjected to earthquakes that shook homes and terrified the residents, who felt a slight earthquake, and while websites affiliated with the armed forces confirmed that the cause was a plane that broke the sound barrier, seismological authorities reported that no seismic activity was recorded.
– In September 2020, a fighter jet’s breach of the sound barrier rattled windows across Paris, halted French Open tennis matches briefly, and sent residents scrambling to call emergency services.
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