Strasbourg (AFP)
The injection activities on geothermal wells north of Strasbourg will resume only with administrative authorization, when the origin of the earthquakes that rocked the Alsatian capital has been determined, it was reported Thursday from the prefecture of Lower Rhine.
Tuesday seismologists and researchers had estimated "possible" that the earthquake was caused by the geothermal activities conducted by the company Fonroche in Reichstett, north of Strasbourg, which the company strongly denies, saying the epicenter is " decorrelated from (his) work area ".
For the time being, the National Seismic Surveillance Network (RéNaSS) in Strasbourg qualifies these two phenomena as "induced events", that is to say "produced directly or indirectly by human activities".
A 2016 decree, taken to regulate the geothermal works carried out by the Fonroche company in Reichstett, north of Strasbourg, provides for "the gradual cessation of operations in progress" in the event of "reaching the threshold of 2 on the scale of Richter ", explains the prefecture.
Coincidentally, the injection operations had already been suspended on 8 November in the wells of the Reichstett site, after a test phase. The resumption of well stimulation activity was in principle scheduled for the end of the year.
It is now up to the Regional Directorate of the Environment, Planning and Housing (DREAL) to authorize or not the resumption of these activities when the analysis of the seismic situation will be completed, said the prefecture. The duration of this expertise is not determined.
"All other operations on site are maintained and can continue, in full agreement with the authorities," said Fonroche Thursday in a statement.
"At this stage of analysis, no origin of the earthquake (natural or induced) can be advanced," said the prefecture of Bas-Rhin in a statement, the day after a first meeting between the NASS, the DREAL and the geothermal operators. A second meeting is planned next week.
A shake with a magnitude of 3.1 on the open scale of Richter had made itself felt Tuesday early in the afternoon in Strasbourg, without causing injuries or major damage.
Another mild earthquake occurred Wednesday just before midnight, a magnitude of 2.6 with an epicenter close to that of Tuesday's earthquake, according to the RéNaSS.
© 2019 AFP