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Deterministic 0-5Hz Ground Motion Simulations of the Mw 6.5, 30 October 2016 Norcia, Italy Earthquake

Session: Physics-Based Earthquake Rupture Modeling and Strong Motion Simulations I

Type: Oral

Date: 4/22/2021

Presentation Time: 02:15 PM Pacific

Description: 

The October 30 2016 M6.5 Norcia, Italy earthquake caused extensive damage to buildings in the epicentral area. The earthquake was well recorded by a dense network of strong motion stations, including 14 stations located within a 5km distance from the two causative faults. In this study we used numerical simulations, to analyze ground motion characteristics recorded during the earthquake. Sets of synthetic ground motions, accounting for seismic wave generation and propagation in a local 3D velocity model, and validated against recorded data, were used to investigate the sensitivity of near-fault ground motion amplitude to the spatial slip pattern, and surface topography effects on observed and simulated ground motion amplification.

The simulations were performed in the frequency range of 0-5Hz using a physics based deterministic approach in modeling the earthquake rupture and elastic wave propagation. We used SW4, a finite difference code which uses a topography conforming curvilinear mesh, designed to model surface topography with high numerical accuracy.

Our results suggest that due to its direct correlation with the local slip pattern and upward rupture directivity effects, the spatial pattern of the horizontal near-fault ground motion generated during the earthquake, was complex, and can be characterized by several local minima and maxima. Because of the limited stations density, the network that recorded the earthquake might have missed the local minima and maxima in the near-fault region. Our simulations show that in several areas located above the fault planes, the computed PGV is higher than both the recorded PGV and that predicted by the empirical models. Also, ground motions computed with and without surface topography indicate that on average the PGV is 30% higher for models with surface topography, and that there is a clear correlation between the PGV and local topography, with the PGV being higher at mountains and hills’ peaks. In contrast, spatial variations of simulated PGA does not correlate with the surface topography.

Presenting Author: Aybige Akinci

Student Presenter: No

Authors