Seismologists in Denmark and Sweden on Monday registered powerful blasts in the areas of the Nord Stream gas leaks, Sweden's National Seismology Centre (SNSN) at the Uppsala University told public broadcaster SVT on Tuesday, APA reports.
"There is no doubt that these were explosions," SNSN seismologist Bjorn Lund told SVT.
A seismograph on the Danish island of Bornholm, near where the leaks had occurred, twice recorded spikes representing earth tremors on Monday, the day on which the Nord Stream 1 and 2 gas pipelines underwent dramatic falls in pressure, German geological research center GFZ said.
The seismograph recorded near-silence until 0003 GMT (2 am local time) when there was a spike representing a tremor in the earth followed by a continuous hissing waveform. The pattern repeated itself at 1700.
European politicians and security experts have suggested that the pipeline rupture near Bornholm could have been caused by sabotage.
GFZ declined to be drawn on whether the tremors recorded could have been the result of an explosion.
Nord Stream 2 depressurized
Nord Stream 2 was first reported to have depressurized on Monday afternoon. The depressurization in the Nord Stream 1 pipeline was reported in the early evening, shortly after the second of the two spikes.
"There was a spike and then regular noise," said GFZ spokesperson Josef Zens. "We cannot say if that could be gas streaming out."