Firm rule out link between geothermal activities and recent earthquakes in Strasbourg

Drilling rig on site of Vendenheim project, Alsace/ France (source: Fonroche)
Alexander Richter 14 Nov 2019

French geothermal developer Fonroche Géothermie refutes links of its drilling activities at its geothermal project in Vendenheim, Alsace with recent seismic events recorded in the region.

A new earthquake was felt Wednesday, November 13 in the Bas-Rhin, five kilometers from Strasbourg. The small earthquake, with a magnitude of 2.6, comes the day after a shock of 3.1 which affected the Alsatian capital. Some groups point to industrial activities that may have triggered these events. The French group Fonroche, which operates a geothermal site in Vendenheim (Bas-Rhin), however excluded any link with its operations.

According to the prefecture of Bas-Rhin, the earthquake of November 12 caused no injuries. The authorities are simply reporting “minor damage” like falling tiles. The small earthquakes recorded in Strasbourg still raise questions. Several scientists have suggested that geothermal activities could be the cause of these shocks. The earthquake of November 13 has been described as an “induced event” by the French Seismological Central Bureau and the National Seismic Surveillance Network of the National Seismic Surveillance Network (BCSF-RéNaSS) in Strasbourg. “An induced earthquake is an earthquake produced directly or indirectly by human activities,” the two organizations said in a statement.

“Here, the series of events is located in the environment close to the deep geothermal site of Vendenheim operated by Fonroche Géothermie. Since the beginning of the operations on this site (March 2018), the BCSF-RéNaSS has located in this zone a hundred of seismic events qualified as induced with the magnitude did not exceed 2.0 “, supplements BCSF-RéNaSS in a statement.

According to the experts, these last seismicity rates recorded in Strasbourg are higher than the natural seismic activity known in the Rhine ditch. These last earthquakes were also recorded at shallow depths (about 5 kilometers). BCSF-RéNaSS researchers argue that the natural earthquakes of the Rhine ditch generally occur at a greater depth.

However, the Fonroche group rejected such a link with its geothermal site. “Our drilling activity can cause seismic activity, but with a maximum intensity of 1.5 which can be felt up to one kilometer. No more. It’s impossible to be at the origin of an event whose epicenter is 5 kilometers away “, justifies Jean-Philippe Soulé, director of the Vendenheim site near Rue 89 Strasbourg. The company adds that the activities have been stopped in Vendenheim since 8 November.

“Additional analyzes will be conducted to confirm or refute the induced origin of the series of events of November 12, 2019”, provide for their part the researchers of BCSF-RéNaSS.

In earlier news this week Fonroche praises the potential of lithium in Alsace, as we reported. The company is said to plan to invest EUR 320 million in Alsace by 2023.

Source: L’usine Nouvelle