Swiss geothermal drilling upsets neighbours

A series of small earthquakes over the past month caused by Swiss drilling for a geothermal power plant are causing alarm on the border between Switzerland, France and Germany.

There were no reports of damage after the latest tremor during the night to Tuesday, measuring 3.2 on the Richter scale.

However, it prompted a flurry of calls to emergency services, authorities around the northern Swiss city of Basel said.

It was the third quake of a similar magnitude to shake the normally tranquil area straddling the three countries since December 8, on top of minor tremors.

“The first time around, I was really scared. It was like a rockfall and glasses were tinkling in the cupboard. I didn’t know what was happening,” said Catherine Wuest, a shopkeeper in Basel.

Switzerland’s seismological institute said the new tremor was caused by the soundings for the country’s first geothermal power plant, which involve injecting pressurised water more than 5,000 metres (three miles) underground.

The local parliamentarian and mayor of neighbouring Saint Louis in France, Jean Ueberschlag, wrote to Swiss authorities recently demanding that the project be halted.

“You don’t have the right to play around with the safety of our populations,” he complained.

Geopower, the company heading the “Deep Heat Mining” pilot project in Basel, stopped work last month after it acknowledged that its soundings were causing the earth to move.

Earthquakes are rarely of significant strength in Switzerland, but Basel was the epicentre of the largest known tremor north of the Alps in 1356, when the city was virtually destroyed by fires that broke out afterwards.

People in Switzerland’s third largest city, which is wedged between southern Germany and eastern France, have got used to the tremors following explanations by local authorities.

“But it’s not comfortable, not at all nice,” said Wuest.

Local authorities are promising to deal with the issue at their next council meeting on January 30 and may even drop the pioneering project to heat some 2,700 homes and provide electricity for 10,000 more in Basel.

“We’re a bit nervous of course because the experts can’t tell us how many tremors we’re in for,” said Marc Keller, a spokesman for Basel’s public works department.

The project for cheap, environmentally friendly energy has cost 60 million Swiss francs (37.5 million euros) so far.

Nicholas Deichmann of the Swiss Seismological Institute, said small tremors were to be expected from the pressurised water injections but similar projects in Australia, Japan and the United States had never triggered anything as strong.

“You can’t rule out further tremors of similar strength, if not stronger, because the water is in the rock and will only disappear slowly,” he explained.

Deichmann said the project by Geopower had been undertaken without a proper seismic risk assessment, even though seismologists regard the Basel region as “fragile.”

Source: AFP