2019 earthquake in Ardèche: did a Lafarge cement quarry play a triggering role?

2019 earthquake in Ardèche: did a Lafarge cement quarry play a triggering role?

Are human activities involved in the exceptionally intense earthquake that hit the Ardèche in November 2019? This track is being seriously studied by a team of researchers. They are particularly interested in the role that a career in the Lafarge cement group could have played. An excerpt from “Further investigation” from January 21, 2021.

Further investigation.  Earthquake in Ardèche in 2019: could the Lafarge quarry have played a triggering role?

It is the strongest earthquake in metropolitan France in fifty years, with a magnitude of 5 on the Richter scale. On November 11, 2019, it struck the Ardèche, causing four injuries and significant damage. In Teil in particular, the municipality most affected, it is the concern: the earth trembled near the Cruas nuclear power plant, reactivating the La Rouvière fault.

The epicenter of the earthquake is just one kilometer from the earth’s surface. It is located almost below a quarry of the cement manufacturer Lafarge. In the scientific community, a question arises very quickly: could this quarry, exploited for nearly two centuries, trigger the earthquake?

“The quarry undoubtedly had the effect of advancing the occurrence of the earthquake”

In Nice, a team of researchers has been working on the subject for over a year. They modeled the evolution of the quarry since 1833, and calculated the volume of rock extracted. In their post, they conclude that the quarry could be the straw that broke the camel’s back.

Here are their conclusions, which one of these researchers exposes in “Complément d’inquête”. Yes “We can conclude that this quarry had a triggering effect for this earthquake”, he doesn’t think that “The forces induced by the quarry may explain why this earthquake grew up to magnitude 5“. According to him, this earthquake could have happened, “Naturally, in 10,000 or 20,000 years”. The effect of the career would therefore have been, “Undoubtedly, to advance the occurrence of the earthquake”.

Contacted, Lafarge did not wish to grant an interview to “Further investigation”. The company does not recognize any responsibility for the earthquake, because other experts, called on by the cement manufacturer, put forward another hypothesis: the rainy episodes which preceded it could have played a more important role than the career in its triggering. Since then, to reassure residents, Lafarge has reduced the power of its shots in the quarry.

Excerpt from “When men make the earth tremble”, a report to see in “Complément d’études” on January 21, 2021.

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