The majority of the Haut-Rhin '' département '' , including Fessenheim , is classified as being in a zone of moderate seismicity ; however , the southern third is in a medium-risk zone . The most recent earthquake in this zone , with a magnitude 4.7 , took place in this southern third at Sierentz in July 1980 . The last major earthquake in the region was the 1356 Basel earthquake , estimated to have had a Mw magnitude of up to 7.1
1356 Basel earthquake
1356 Basel earthquake
Fessenheim Nuclear Power Plant