Constraining Between-Event Variability of Kinematic Rupture Scenarios by Empirical Ground-Motion Model: A Case Study in Central Italy

Abstract

The region of central Italy is well known for its moderate-to-large earthquakes. Events such as 2016 Mw 6.2 Amatrice, generated in the shallow extensional tectonic regime, motivate numerical simulations to gain insights into source-related ground-motion complexities. We utilize a hybrid integral–composite kinematic rupture model by Gallovič and Brokešová (2007) to predict ground motions for other hypothetical Amatrice fault rupture scenarios (scenario events). The synthetic seismograms are computed in 1D crustal velocity models, including region-specific 1D profiles for selected stations up to 10 Hz. We create more than ten thousand rupture scenarios by varying source parameters. The resulting distributions of synthetic spectral accelerations at periods 0.2–2 s agree with the empirical nonergodic ground-motion model ofSgobbaetal.(2021)forcentral Italy in terms of the mean and total variability. However, statistical mixed-effect analysis of the residuals indicates that the between-eventvariability of the scenarios exceeds theempirical one significantly. We quan tify the role ofsourcemodelparametersinthemodelinganddemonstratethepivotalroleof theso-called stress parameterthatcontrols high-frequencyradiation. Weproposerestricting thescenariovariability tokeepthebetween-eventvariabilitywithintheempiricalvalue.The presented validation of the scenario variability can be generally utilized in scenario model ing for more realistic physics-based seismic hazard assessment.