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Constraining Between-Event Variability of Kinematic Rupture Scenarios: A Case Study of an Mw6.2 Earthquake in Central Italy

Description: 

The region of Central Italy is well known for its moderate to large normal-fault earthquakes and motivated ground motion modeling to provide insights on source-related complexities. We utilize a hybrid integral-composite kinematic rupture model by Gallovič and Brokešová (2007) to simulate the 2016 Amatrice earthquake (M 6.2) and perform ground motion prediction for other hypothetical Amatrice fault rupture scenarios (scenario events). The synthetic seismograms are computed in 1D crustal velocity models, including site-specific 1D soil profiles for selected stations up to 10 Hz. We optimize the input source parameters using a grid-search method to minimize the spectral acceleration bias between synthetic and recorded near-source strong-motion data at reference rock stations with negligible site effects. Then, we create up to 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 of Sgobba et al. (2021) for Central Italy in terms of the mean and total variability. However, statistical mixed-effect analysis of the residuals indicates that the between-event variability exceeds the empirical one significantly. We quantify the role of source model parameters in the modeling and demonstrate the pivotal role of the so-called stress parameter that controls high-frequency radiation. We suggest narrowing down the variability of the stress parameter to constrain the scenario variability within the empirical values. The presented validation of the scenario variability can be generally utilized in scenario modeling for physics-based seismic hazard assessment.

Session: Understanding and Modeling the Uncertainties in Earthquake Ground Motions

Type: Oral

Date: 4/20/2023

Presentation Time: 10:30 AM (local time)

Presenting Author: Francesca Pacor

Student Presenter: No

Invited Presentation: 

Authors