Studies of long-term seismic activity in any region of the world require the longest historical perspective as possible. In most of the regions of Europe, before the XIIIth and the XIVth centuries, historical sources allow to establish a catalogue of felt earthquakes but the available data give very few information to estimate local intensities and epicentres.

Thus, the knowledge of the seismic activity begins really at this epoch and covers a time period of less than 700 years. From that time, sources from different origins. (chronicles, annotations, parish registers, account registers,…) give us more details on local effects and allow reliable estimation of damages and perceptibility area of the earthquakes. It is then possible to determine the probable epicentral area of the strongest earthquakes and also to estimate their magnitude by comparison with recent earthquakes for which the magnitude has been instrumentally determined.