Comment on “Layered Seismogenic Source Model and Probabilistic Seismic-Hazard Analyses in Central Italy” by Bruno Pace, Laura Peruzza, Giusy Lavecchia, and Paolo Boncio

Abstract

Pace et al. (2006) define a seismogenic model aimed to provide a (time-dependent) seismic-hazard assessment for Central Italy. One of the main novelties of the model is that it introduces seismogenic structures (faults) in seismic-hazard calculations, and it imposes a time behavior on these structures, leading to a time-dependent seismic-hazard assessment. In my opinion, the approach used in this article (1) does not explain the “observed” time distribution of historical earthquakes (one of the few empirical evidence that can be used to check the reliability of any seismic-hazard or earthquake-forecasting model), and (2) uses values of parameters of the statistical distribution that are clearly unreliable. These problems introduce significant biases that potentially make the hazard assessment made by the authorsless reliable that the one obtained by more traditional approaches. In the following, I discuss in detail these points. I focus the attention only on earthquakes with M 5.5