Source parameter estimates for some historical earthquakes in the south-eastern Alps using ground shaking scenarios

Some of the most relevant seismogenic sources in north-eastern Italy, western Slovenia and southern Austria have been studied in the framework of the Interreg IV A HAREIA (Historical And Recent Earthquakes in Italy and in Austria) project. Based on active fault data and historical records we have produced several ground shaking scenarios for some of the biggest known historical earthquakes that have occurred in the studied area. In particular, we compute the maximum peak ground velocity value at 1 Hz (PGV1Hz) for all studied events at every point of the computation grid, which covers the entire area of interest. For each studied earthquake we, then, make a qualitative comparison between the related observed intensity data points and computed scenarios, and select the one that is most consistent. This allows us to determine both the causative fault model and the approximate extended-fault rupturing process at the basis of each earthquake. We have applied this analysis to know historical events such as the Villach (1348), Idrija (1511), Asolo (1695) and Tyrol (1572, 1670, and 1689) earthquakes. We have added to the results obtained from these events several scenarios related to other important events that occurred or we deem possible to occur in the area and for which the causative fault is known. The maximum value obtained from all computed scenarios at a given grid point allows finally the construction of a PGV1Hz map for the area under investigation. Such a map, a main result of this study, can be used as a conservative seismic hazard one for events that might occur on the considered active faults.