An expert believes five explosions detected by seismologists last week in Russian territorial waters may have been caused by small deep water bombs, newspaper Helsingin Sanomat (HS) reported.
Explosions of unknown origin occurred in the Gulf of Finland on Thursday and Friday last week and the activity was noticed by the Institute of Seismology at the University of Helsinki.
Seismologist Jari Kortström told the paper there could have been several reasons for the activity.
The explosions could have been caused by either small depth charges — an anti-submarine warfare weapon — or exploded sea mines, he said.
He estimated that if dynamite was used, it was between 50 and 100 kilos maximum.
The expert also said the explosions to not necessarily denote unusual activity.
For example, when the Finnish Navy conducts exercises in the Gulf of Finland it can use small depth charges to scare away submarines.
It could also have been caused by seabed trawling.
Kortström said the last time similar seismological activity was detected in the Gulf of Finland was more than a year ago.
HS said the explosions took place in territorial waters, about 40 kilometers southwest of Vyborg.
The Finnish Coast Guard is not investigating the cause of the incident as it did not take place in Finnish waters.
Editor: Allan Aksiim, Helen Wright
Source: Helsingin Sanomat