Fears of sabotage as gas pours into Baltic from Nord Stream 1 and 2 pipelines

Gas is pouring into the Baltic Sea from three separate leaks on the Nord Stream 1 and 2 pipelines amid claims by seismologists in Sweden and Denmark of two sharp spikes in undersea activity, possibly indicating explosions, and speculation about sabotage.

A seismograph on the Danish island of Bornholm, near where the leaks occurred, twice recorded spikes on Monday, the day on which the Nord Stream 1 and 2 gas pipelines underwent dramatic falls in pressure, the German geological research centre GFZ said.

A Danish military flight over the leaks brought back striking images from the ruptures, including one showing an area of bubbling gas a kilometre wide on the sea’s surface.

The seismograph recorded near-silence until just after midnight GMT (2am local time), when there was a spike representing a tremor in the earth followed by a continuous hissing wave form. The pattern was repeated at 5pm GMT.

Amid the speculation over sabotage, suspicion immediately turned to potential culprits – with fingers pointed at Russia, whose pipelines were hit, suggesting a further weaponisation of energy supplies to Europe in the midst of the conflict in Ukraine. Not least it was seen as a possible message about the vulnerability of other marine gas infrastructure.

“There are some indications that it is deliberate damage. You have to ask: Who would profit?” one European security source told Reuters. The Danish prime minister said sabotage could not be excluded. Poland’s foreign minister was more forthright, suggesting that the damage could be an act of provocation on behalf of the Kremlin.

Meanwhile the Kremlin spokesperson, Dmitry Peskov, called the news “very concerning” and said that “no option can be ruled out right now”, including sabotage.

The steel pipe itself has a wall of 4.1 cm (1.6 inches) and is coated with steel-reinforced concrete up to 11cm thick. Each section of the pipe weighs 11 tonnes, which goes to 24-25 tonnes after the concrete is applied.

British sources said they believed it may not be possible to determine what occurred with certainty.

One UK insider speculated that any explosions were unlikely to have been caused by a submarine or underwater vehicle, because their presence would have been detected in the relatively shallow Baltic waters. Sections of the pipelines are between 80 metres and 110 metres deep.

The day of drama began when the Danish energy agency said it had found the leaks on the Nord Stream 1 pipeline north-east of the island of Bornholm, and a third in the Nord Stream 2 pipeline in Swedish waters south-east of the island. “This is not a small crack. It’s a really big hole,” the energy agency said.

Underlining the significance of the event, Javier Blas, an energy and commodities commentator for Bloomberg, described the undersea gas pipelines in the region as one of Europe’s most important strategic assets. “The subsea pipelines linking the North Sea gas fields, and then Norway with the rest of the continent and the UK are among the most strategic assets right now for Europe. High time for maximum protection. Cyber-attacks against energy assets are, too, a key risk for Europe,” Blas tweeted.

A five-mile exclusion zone for shipping has been set up around Bornholm, and flights below 1,000 metres have been banned in the area. Methane, the primary component of natural gas, partially dissolves in water, is not toxic and creates no hazard when inhaled in limited quantities.

“Breakage of gas pipelines is extremely rare”, Danish authorities said in a statement. “Therefore we see reason to raise the preparedness level as a result of the incidents we have seen over the past 24 hours.”

Nord Stream AG, the pipeline operator, had on Monday morning reported an unexpected overnight drop of pressure from 105 to 7 bar in Nord Stream 2, which is filled with gas but was cancelled by Olaf Scholz, the German chancellor, shortly before Russia’s invasion of Ukraine.

A further drop of pressure was reported on Monday afternoon in Nord Stream 1, which Russia shut down indefinitely at the start of September, initially saying it needed repairs.

Since no gas has flowed through either of the pipelines since the start of the month, German authorities have been quick to reassure people that the leaks will not affect its plan to fill gas storage tanks in time for winter.

Environmental NGOs said the leaks were likely to cause large-scale damage to the environment. “As soon as methane in gas form raises from the surface of the sea into the atmosphere, it will massively contribute to the greenhouse effect,” said Sascha Müller-Kraenner of the pressure group Environmental Action Germany.