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Natural Local Seismicity

Historical earthquake observations over the past four centuries and instrumental seismological data gathered over the past 30 years clearly show that there is naturally occurring earthquake activity in the Lower Rhone Valley between Martigny and Lake Geneva. The earthquakes near Aigle in 1584, at the Lac d'Emosson reservoir or in the Mont Blanc Massif in 1905, reached a macroseismic intensity of VII (very strong) and can be classified as damaging seismic events. A series of weaker but shallow earthquakes in the municipality of Val d'Illiez in 1953-1954 and 1994-1996, was possibly associated with the filling of the Lac de Salanfe reservoir. They show that the Earth's crust in this area is subjected to stress and that even minor disturbances to the stress field or the hydrological conditions may suffice to trigger seismic events.

Although very small -most likely very shallow - earthquakes occurred at Lavey-Village in 2005-2006, the seismological data available today do not indicate the presence of any active fault zone in the immediate vicinity of Lavey-les-Bains. However, the period of seismic data coverage (a few decades) is much shorter than the typical recurrence interval of larger earthquakes on these faults (in Switzerland at least several centuries ), and they may have gone undetected until today.