Several months after the shutdown of a geothermal project near Strasbourg, which itself had caused several earthquakes, a new 3.9 magnitude earthquake woke up the Alsatian city on Saturday at 5 a.m.
according to the national seismic monitoring network (Renass), based in Strasbourg.
The epicenter of the shock was recorded at a depth of five kilometers, in the town of La Wantzenau, north of the Strasbourg metropolitan area, according to Renass. A aftershock was recorded five minutes later – of magnitude 2.3 – at the same location. The two events were classified as “induced”, that is to say caused by human activity.
“Thank you to the sorcerer’s apprentices of geothermal energy”
The Environmental Monitoring Analysis Department of the CEA (French Atomic Energy and Alternative Energies Commission – CEA-Dase), for its part, indicated a magnitude of 4.3 for the first earthquake. This is the strongest earthquake felt in recent months in the region. “It was really tough this time,” tweeted Alain Fontanel, one of the opposition leaders in the Strasbourg city council. “The whole house shook for a few seconds. Thank you to the sorcerer’s apprentices of deep geothermal energy for this brutal awakening #scary “. Many similar reactions were visible on social media.
A deep geothermal project, with two boreholes five kilometers deep, had been developed until December north of Strasbourg, in the towns of Vendenheim and Reichstett, neighboring La Wantzenau. The Bas-Rhin prefecture announced on December 7 that the project was definitively stopped, after a series of more or less intense earthquakes – including one of magnitude 3.5 on December 4 – and classified as “induced” by the Renass .
“Basel seismic crisis”
Fonroche géothermie, the project leader, admitted that its activities were the source of some earthquakes. “The location and the first estimate of depth make us clearly think that these events are in the continuation of the preceding ones”, declared Saturday Jérôme Vergne, seismologist at the School and observatory of earth sciences of Strasbourg.
“We had continued to record persistent seismic activity in recent months. The basement takes some time to react to the shutdown (of the project), and to regain a state of natural stress, ”he added. “What is astonishing is that today we had the most important earthquake of the sequence”. He referred to the “Basel seismic crisis”, the Swiss city having also been plagued by “lower magnitude” earthquakes after the shutdown of a local geothermal project in the 2000s.