A new magnitude 3.4 earthquake, according to the National Seismic Monitoring Network (Rénass), shook the Strasbourg metropolitan area on Friday.
These "induced" shocks, that is to say due to human activity, occurred a few kilometers from a site hosting a geothermal power plant project, which the Bas-Rhin prefecture announced on December 7 that it was shut down. final.
A new magnitude 3.4 earthquake, according to the National Seismic Monitoring Network (Rénass), shook the Strasbourg metropolitan area on Friday shortly after 7:30 p.m., a few weeks after the shutdown of a geothermal power plant project that triggered seismic activity abnormal in the region in recent months.
The earth shook at 7:33 p.m. precisely and the epicenter of the shock was again located north of Strasbourg, in the town of La Wantzenau.
Two softer aftershocks, magnitude 1.9 and 2.2 were felt shortly after.
"Earthquake felt in the perimeter of the geothermal power station of Vendenheim (suburb of Strasbourg) at 19:33. The event was located near the injection well of the power station being shut down", wrote the company Fonroche Géothermie which leads the project.
An earthquake of magnitude 2.1 had already been felt Tuesday evening around 11:15 p.m. in the same area.
Shakes due to human activity
All these "induced" shocks, that is to say due to human activity, occurred a few kilometers from a site hosting this geothermal power plant project led north of Strasbourg, in the towns of Vendenheim and Reichstett, and which the Bas-Rhin prefecture announced on December 7 the final stop, after several other induced earthquakes more or less intense (including one of magnitude 3.5 at the beginning of December) which have occurred in recent months.
"The wells are under observation. The reservoir is slowly returning to its natural pressure and this release is accompanied by seismicity," adds Fonroche, ensuring that the information was immediately communicated to the site monitoring committee and to the competent authorities.
"New earthquake on the territory of the Eurometropolis of Strasbourg. The second in three days with this time a strong magnitude of 3.6 (then reassessed at 3.4 by the Rénass, editor's note). We are definitely not done with it yet. the consequences of deep geothermal energy. Much too deep and invasive, "Strasbourg opposition councilor Alain Fontanel (LREM) wrote on Twitter, with the hashtag #apprentisorcier.
Despite the interesting potential of geothermal energy as green energy, the Eurometropolis of Strasbourg, in the hands of environmentalists, had also campaigned for the stopping of the Reichstett-Vendenheim geothermal power plant project, in view of the seismic activity caused.
The geothermal project interrupted in December
As part of its geothermal project, Fonroche had drilled two boreholes 5 kilometers deep, in order to draw hot water from the subsoil to exploit its energy potential on the surface before reinjecting it underground at very high pressure.
An electricity production plant had also been built.
This project, for which 100 million euros had been invested, was stopped at the beginning of December and Fonroche had to gradually reduce the flow of the injected water.
The company had warned that the operation, scheduled to last several weeks, could cause further shocks.
Several dozen residents of municipalities north of Strasbourg have observed minor damage to their homes as a result of these earthquakes in recent months and have made claims for compensation to Fonroche.
In the wake of the shutdown of this plant, the three other geothermal projects developed in the Strasbourg metropolitan area were also suspended pending extensive feasibility studies on potential risks.