Seismic signals indicating possible explosion recorded near Balticconnector gas pipeline

Seismic signals have been recorded in the vicinity of the Balticconnector gas pipeline between Finland and Estonia, indicating a possible explosion had occurred around the time an unusual drop in pressure was observed.

To remind, Balticconnector was shut down at midnight on October 8 after Finnish and Estonian transmission system operators (TSOs) Gasgrid and Elering observed an abnormal pressure drop shortly before 2 a.m., suspecting that there was a leak in the pipe.

Following the launch of an investigation, Finnish authorities reported that the damage was not caused by the normal gas transmission process and that it is likely that the damage to the gas pipeline was caused by external activity.

The NORSAR research foundation which specializes in seismology and seismic monitoring now reported that it had recorded seismic signals near the gas pipeline that indicate a possible explosion occurred at around 01:20 on October 8.

The event was located approximately 40 kilometers north of Paldiski, Estonia, close to where the Balticconnector pipeline crosses the Nord Stream 1 pipeline. The magnitude has been estimated at 1 on the Richter scale, much lower than the Nord Stream explosion detected in September 2022. 

The seismologists analyzed data from the Finnish seismic network, including a group of sensors called the FINES seismic array, which shows a clear event at 01:20 Finnish time, corresponding with the approximate time of the reports of a drop in pressure in the pipeline.

NORSAR stated it was unable to determine if the event was caused by a sudden release of gas under high pressure, due to rupturing of the pipeline, or from the detonation of an explosive. 

The Finnish National Bureau of Investigation (NBI) launched a criminal investigation on October 10 into a possibly intentional damaging of the gas pipeline as aggravated criminal mischief.

NBI sent Estonian authorities a European Investigation Order and close cooperation in criminal investigation started. The Estonian authorities are also investigating the fault in the telecommunications cable that was identified at about the same time.

“Examination and analysis of the material are still in an early stage. At this point, we can however state that in the vicinity of the leak of the gas pipeline, traces have been detected in the seabed,” NBI stated.

In a separate statement, Gasgrid said that the earliest possible commissioning date of the Balticconnector pipeline would be at the beginning of April 2024 since planning the repair work, mobilization of necessary underwater equipment, and the actual repair measures, including the inspection of the repaired pipe section and commissioning, will last at least five months based on preliminary expert assessments.

Balticconnector is the first gas pipeline between Finland and Estonia. The project, which entered into commercial use at the start of 2020, ends Finland’s isolation from the EU gas market and helps ensure the energy security of supply in the region. 

The 152-kilometer-long gas pipeline is bi-directional and has a transmission capacity of 7.2 million cubic meters of gas per day.