Mysterious waves shook the earth in Denmark !

Copenhagen. Mild tremors have been recorded on the island of Bornholm in Denmark . Many mild tremors have puzzled scientists. They say that the tremors were caused by sound pressure waves from an unknown source. When the vibrations of an object or source cause vibrations to spread in air, water or solids as well, then it is called a sound pressure wave. Then seismologists said that it was probably caused by controlled explosions in Poland, 140 km to the south. The Geological Survey of