The seismicity of the Central Apennines (Italy) studied by means of a physics-based earthquake simulator

Abstract

The application of a physics-based earthquake simulation algorithm to the Central Apennines, where the 2016-2017 seismic sequence occurred, allowed the compilation of a synthetic seismic catalog lasting 100 kyr, and containing more than 500,000 M ≥ 4.0 events, without limitations in terms of completeness, homogeneity and time duration. This simulator is based on an algorithm constrained by several faulting and source parameters. The seismogenic model upon which we applied the simulator code, was derived from the Database of Individual Seismogenic Sources including all the fault systems that are recognized in the Central Apennines. The application of our simulation algorithm provides typical features in time, space and magnitude behavior of the seismicity, which are comparable with the observations. These features include long-term periodicity and a realistic earthquake magnitude distribution. The statistical distribution of earthquakes with M ≥ 6.0 on single faults exhibits a fairly clear pseudo-periodic behavior, with a coefficient of variation Cv of the order of 0.4-0.8. We found in our synthetic catalog a clear trend of long-term acceleration of seismic activity preceding M ≥ 6.0 earthquakes and quiescence following those earthquakes. Lastly, as an example of a possible use of synthetic catalogs, an attenuation law was applied to all the events reported in the synthetic catalog for the production of maps showing the exceedance probability of given values of peak acceleration (PGA) in the investigated territory.