NUMERICAL SIMULATIONS OF THE TSUNAMI INDUCED BY THE 1627 EARTHQUAKE AFFECTING GARGANO, SOUTHERN ITALY

A study of the historical tsunami that occurred on 30 July 1627 in Gar gano, Apulia, southern Italy, has been conducted by performing numeric al simulations based on integrating shallow water equations via a fini te-element (FE) technique. The tsunami was generated by an I=XI earthq uake which produced severe damage in the Gargano promontory. Macroseis mic observations are not sufficient to determine, unambiguously, the e picentre and the generative fault position. In this study we have assu med a dip-slip focal mechanism which is known to be the most effective tsunami generation. Since the source location is uncertain, different simulations have been carried out assuming that the fault is placed o n land (two cases) and offshore (two cases). The Adriatic basin facing the northern coast of Gargano has been covered by a triangle-based me sh, with triangle sizes adapted to the variable bathymetry, which prov ed to be advantageous in describing the irregular coastlines. The avai lable historical observations concerning the tsunami are scarce and ch iefly qualitative. Yet, comparing data with the results of the numeric al simulations gives some important hints on the position of the genet ic fault. Of all the sources studied, the one matching the observation s better is the inshore fault causing the uplift of the sea block faci ng the Lesina lake. Accordingly, at the present stage of research, thi s fault can be assumed as that responsible for the 1627 earthquake and tsunami.