The reassessment of the 1795 and 1796 earthquakes is part of the upgrade of the Earthquake Catalogue of Switzerland (ECOS). It is of major importance with respect to both history and seismology. Although the events have been the subject of a large number of publications, none of these studies was based on critical methods. The re-evaluation of the events rests on a new, reliable database established through investigations in archives and libraries. Using the data made available by the historical information, we assigned site intensities, adopting the criteria established by the European Macroseismic Scale EMS 98 (Grünthal 1998). Considering the broad spectrum of the given information, we assigned the minimum and maximum possible values (Imin; Imax) and set a most probably intensity value (Iw).

The results show that previously the intensity of the 1796 event was overestimated due to a misinterpretation of the written records. We therefore recommend a reduction of the epicentral intensity to Io = VII and a moment magnitude of Mw = 5.3. Also for the 1795 earthquake we recommend Io = VII and Mw = 5.3. Although the estimate of the strength of the 1796 event has to be reduced on the basis of our re-evalution, these two earthquakes are still significant for the region, and our results will have an impact on the seismic hazard assessment of the area.