 We have quantitative data concerning past earthquakes only from the beginning of the 20 century (as the invention of the seismograph is from the very late 19 century), but humanity is forced to deal with earthquakes since the very beginning of its time.So, we have an extremely limited information to deal with a reliable seismic risk.As a result, a methodology for reconstruction of historical earthquakes was held during the 20 century, but it has brought a very partial results, especially for archaic earthquakes.