The Grand-Ouest of France was shaken from Brittany to Normandy, from Berry to Anjou and Touraine, from Limousin to Poitou, from Saintonge to Aunis and Bordelais [fr], in Auvergne, in the Morvan and as far as Île-de-France.

[9] The intensity was of the order of VII–VIII at the epicenter, the centre of the tremor not being located in the heart of the marshland as initially advanced but more to the west, at sea, in the bay of Bourgneuf.

In the hardest hit area, the earthquake is estimated to have reached intensity VIII due to the lower resistance of the sediments making up the marsh, which locally amplified the seismic movement.

[2] Intensity decreases with increasing distance but remained significant in Nantes and Les Sables-d'Olonne (VI–VII), La Rochelle, Ile d'Oléron and Belle-Île-en-Mer (VI).

Lightweight constructions were not, however, the only buildings affected by the earthquake, as one testimony reports: "the spire of the steeple, all in dressed stone, built with cement, is on the verge of falling".

[10][12] Damage was also noted in La Garnache, 6 km northeast of Challans, in the Bois-de-Céné marsh area, in Barbâtre, a town which, partly destroyed by the earthquake, lost its title of municipality and was united in Noirmoutier, and Bourgneuf-en-Retz.

The unique case of a house destroyed in Champtoceaux in Maine-et-Loire, a village on the left bank of the Loire about 25 kilometers upstream from Nantes was also reported.

They could equally be explained by a sudden thaw removing the ice dams in the rivers reported a few weeks earlier as by a tidal wave.

[10] Beyond the destruction of buildings and superstructures, the more or less long-term consequences of the earthquake on the local economy were reported in particular to the central administration of Loire-Inférieure by the municipal administration of Herbignac which indicates the 1st March 1799 (11 Ventose year VII) that the population of the municipalities of La Briere in St-Hyphard and Herbignac that "... usually draw clods which are used for heating the township and still supply all the surrounding townships and allow them to live for two thirds of the year" showed losses caused by the earthquake.

Likewise, the municipal administration of Machecoul pointed out that if the owners succeeded in partially re-establishing the crops destroyed by the civil war, they had not yet derived any benefit from it at the date of the earthquake and that "the lowlands both in the upper and lower marshes of the municipality de Machecoul will not yet produce anything this year, these lands have been under water for more than two months, the wheat will be rotten like last year".

In this period of development of the written press, these pages are important sources of information for future seismology when the original records are lost: they indeed publish the testimonies and the communiques of the authorities, directly or with the hindsight and analysis of their own.

[10][12] No other example of an earthquake of such magnitude has been identified in the area The only tremors recorded are minor and were noted on the island of Noirmoutier (23 August 1747, 5 February 1833, 15 October 1945 and 22 June 2005) and Bourgneuf-en-Retz (7 April 1767).