Abstract
The purpose of this study was to apply a double-branching model to forecasting of moderate-to-large Italian seismicity within the Collaboratory Study for Earthquake Predictability project. This project is designed for statistical evaluations and comparisons of various forecasting models, on both the global and regional scales. This proposed double-branching model is time-dependent, as it assumes that each earthquake can generate, or is correlated with, other earthquakes through physical mechanisms that act on different spatio-temporal scales. Specifically, it consists of an application of two branching processes, in which any earthquake can trigger a family of later events on different space-time scales. In our recent study [Lombardi and Marzocchi 2009], we applied this model to a declustered historical database that included the strong Italian seismicity from over the last few centuries. This catalog only allowed us to describe the long-term time evolution of moderate-to-strong seismicity. Here, we have applied this double-branching model to a new database that has allowed us to describe both short-term clustering and long-term features at the same time. As the model can produce forecasting calculations of future seismicity, we provide some probability maps of occurrence of predicted events over different temporal windows.
Highlights
The modeling of the spatio-temporal distributions of moderate-to-large earthquakes is a major goal of geophysical investigations
This assumption explains the current use of the stationary Poisson paradigm in many practical applications that are related to long-term behavior of earthquake occurrence, such as in the formulation of probabilistic seismic-hazardassessment methodologies based on the Cornell method [Cornell 1968] and in the evaluation of earthquake prediction/forecasting models [e.g., Kagan and Jackson 1994, Frankel 1995, Varotsos et al 1996, Gross and Rundle 1998, Kossobokov et al 1999, Marzocchi et al 2003]
By considering the model estimated by Lombardi and Marzocchi [2009] with the CPTI04 catalog, we obtained the map of the probability distribution u2(x, y)
Summary
The modeling of the spatio-temporal distributions of moderate-to-large earthquakes is a major goal of geophysical investigations. We apply this model to events above a local magnitude (ML) of 4.5 that have occurred in Italy over about the last century This last dataset includes aftershock sequences, and it allows us to model the short-term features of the seismicity, which was ruled out in our previous study [Lombardi and Marzocchi 2009]. The residual seismicity that is obtained by filtering the original database of these short-term triggering effects is ascribed to the superposition of two physical processes: the time-independent and spatially variable tectonic loading n2 = o2·u2(x, y), and the long-term coupling between events. Confirmed by applying residual analysis [Ogata 1998, Lombardi and Marzocchi 2009] to the CPTI08 dataset This diagnostic technique confirms that if a point process model with intensity m(t) describes the temporal evolution of the seismicity well, the transformed data t. By considering the model estimated by Lombardi and Marzocchi [2009] (the first application of DBM to Italian seismicity) with the CPTI04 catalog, we obtained the map of the probability distribution u2(x, y)
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