Analysis of the macroseismic cumulative damage in the seismic sequences in Italy

Abstract

During seismic sequences, macroseismic damage effects cannot always be distinguished and assigned with certainty to individual shocks. In particular, the intensity that quantifies the effects of the earthquakes is a classification of the cumulative effect of all the shocks that occurred. This affects the estimation of the macroseismic parameters that can be obtained (location, magnitude), which cannot have the same reliability as single mainshocks, with implications for seismotectonics or hazard assessment. To try to solve this problem, a methodology was recently proposed using the case study of the event of 2016, October 30th (Mw = 6.6), based on the deletion of intensities above an established threshold for common localities hit by previous earthquakes during a sequence. In this paper, we analyse the variation of earthquake parameters of some Italian sequences by systematically applying this methodology and varying the cut threshold of intensity. The results provide a more complete evaluation of the proposed method and its reliability and suggest an alternative approach based on all available MDPs to compute earthquake parameters of aftershocks.