U.E.I. d'Estudis Medievals, Instituciò Milà i Fontanals, C.S.I.C., Barcellona (Catalonia). Spain

The May 1448 earthquake. the last destructive one that took place in Catalonia in the Middle Ages, was known chiefly from several chronistic and narrative medieval sources. To these sources I add new previously unknown data proceeding Eroin documentary archival sources in Barcelona, and other data that up to now have been wrongly considered as a consequence of the weak quake recorded in September 1450. They allow us to locate the epicentre in the Vall&s Oriental, around Llinars, to deny the existence of two almost simultaneous earthquakes, and to extend the range of the earthquake damage. to pinpoint them better and to suppose that the effects of the 1448 earthquake were more important than we had previously thought. All this information leads to several reflections on compulsory critical analysis of historical seismic documentary sources in order for them to be useful to historical seismicity. Finally. by the opposition of the three lands of documentary sources that refer to the damage caused by the earthquake in the township of Mataro. I show how natural catastrophes could be manipulated, and the skill of a society in exploiting them to deal with an adverse situation.