The BCSF-Rénass published in December 2022 the mapping of the maximum communal intensities of the hexagonal France for the period 1921 – 2021. The values shown are extracted from the BCSF-Rénass (1) macroseismic database.
Since its creation (1921), the Bureau central sismologique français has been investigating the seismic effects produced by earthquakes on the territory. This observation activity, non-instrumental and continuous for 100 years, is today in charge of the national observation service (SNO) BCSF-Rénass. The set of macro-seismic surveys, collecting testimonies of the effects observed by the population and the authorities, allowed the estimation of the intensity of the ground shaking for 125795 communal points, based on different scales of macro-seismic intensities at 12 degrees, all converted to the EMS-98 scale.
This map allows to visualize the maximum seismic intensities for each French commune having felt the effects of earthquakes during this period.
Some of the intensities indicated in border areas or coastal areas can obviously be produced by earthquakes located outside the hexagon. In 100 years, 33 earthquakes have reached maximum intensities of VII or VII-VIII, 9 intensities VIII. The maximum intensity reached over this period is the Arette earthquake in August 1967 (intensity VIII-IX).
(1) French Central Seismological Office, National Seismic Monitoring Network.
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