Seismogenic sources responsible for destructive earthquakes in NE Italy.

Abstract

The paper discusses the seismogenic characteristics of NE Italy related to earthquakes with Mw≥5.5, and the geometry of the related sources re-drawn by following the DISS standard procedure. Therefore, this paper represents an update of a previous work which investigated the Prealpine area between the Lessini Mountains and the Italian-Slovenian border, and defined the seismogenic sources potentially responsible for earthquakes with Mw≥6 within the GNDT-2000 project. For inclusion in the DISS, the sources of that previous work have been processed following a 3-step process, which is a routine procedure used each time the parameters of a seismogenic source are taken from published works. The first step was a consistency check of the source dimensions (aspect ratio, from length/width relationships and according to the fault type), of their position and geometry (minimum and maximum depth and dip), and of some seismological parameters of the expected/associated earthquakes (slip, Mw from both Wells and Coppersmith’s and Hanks and Kanamori’s relationships, and seismic moment). All these parameters were verified by using the Fault Studio software. The second step involved the inclusion of seismological information, such as the measured stress drop, to infer slip on the fault plane and rupture area and to compare these parameters with the rupture area hypothesised on the basis of the geological information. The third step of the data processing deals with the analysis of the intermediate size historical seismicity (5.5≤Mw≤6.0) and the possible association with faults belonging to the identified active thrust systems of the eastern Southalpine Chain front or to more internal faults (both thrust and strike-slip faults) not included in the data set of the previous work.