An application of the NonErgodic ground ShaKing (NESK) approach to an historical earthquake scenario: The case-study of the 1915 Fucino earthquake (central Italy)

Abstract

The 1915, Mw6.7, Fucino earthquake is one of the most destructive events occurred in the central-southern Apennines (Central Italy) in pre-instrumental era, involving normal faulting in a deep alluvial basin. This study shows the application of the empirical non-ergodic approach (NESK method) for mapping ground shaking related to this historical event, taking into account the regional features of source, propagation and site contributions. Corrections of the source-region and spatially correlated maps of site and path residuals are combined with median prediction at the reference rock (i.e. without site amplification) to generate spatially variable ground shaking and associated variability in terms of peak ground acceleration and spectral ordinates at vibration periods from 0.01s to 2s. The method captures the main spatial non-stationarities and anisotropies of the shaking fields produced by this earthquake in and around the Fucino basin. In particular, we obtain patterns of seismic motion quite in accordance with the results of other methods and the macroseismic intensity field. Marked amplifications of the shaking in the long-periods are also captured, due to the coupling of 3D site effects, especially in the deeper portion of the basin, with propagation effects mainly focused towards the eastern part of the fault. These results confirm that the non-ergodic shaking scenarios from NESK can provide useful indications even in the case of very complex seismological and geological contexts, such as in the case of strong events in deep sedimentary basins.