The magnitude 4 earthquake felt this Monday shortly after 9:00 p.m. in the Montbéliard region, in the Doubs, near the Swiss border, is the “third in a few months in the region,” according to the mayor of a affected municipality. Is this phenomenon really more frequent than in other parts of this region? BFMTV.com posed the question to a seismologist.
A recently affected town
“We are no longer surprised, we are beginning to know how to recognize an earthquake,” he testified Monday night in blue france Serge Delfils, mayor of the city of Blamont, in the Doubs. The councilor has counted three earthquakes in a few months in the surrounding area, and believes that they are “increasingly frequent but also increasingly brief for a year.”
The site of the French Central and Seismological Office – National Seismic Monitoring Network (BCSF-Rénass) – showing the fifty most significant earthquakes that occurred around the epicenter of this latest earthquake, seems at first glance to support this observation. . If we look at the large earthquakes in the surrounding area, the town of Belfort seems to have been particularly affected recently.
On March 22, an earthquake of magnitude 4.2 occurred 30 kilometers from Belfort, for example, and was felt in northwestern Switzerland.
However, this map only lists the most significant tremors. If we zoom out, several episodes were also recorded in other places. Also, in the long term, no major anomalies have been detected, says seismologist Yann Klinger.
“No increase in average seismicity”
“If we do an analysis of seismicity in recent years, there is no particular increase in average seismicity: it is true in this region and in general,” explains this CNRS research director to the Institut de physique du globe in Paris.
“[La région autour de la chaîne de montagne du] The Jura is one of the fairly classic seismic zones in France”, he points out. The entire “front from the Alps to the Nice region” actually suffers from the deformation generated by the northward rise of the African plate, which pushes the Eurasian plate. plate on the way.
“But it is not a very strong tectonic activity, because it is not a plate boundary like in Turkey”, specifies the researcher. “With magnitude 4, we are talking about a displacement of one centimeter in the plate.”
On the scale of metropolitan France, only about thirty of the 4,000 earthquakes recorded each year are felt by the population, according to the Résif-Epos seismological network, and it is very rare for an earthquake to exceed magnitude 6.
Source: BFM TV
