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Insight From 3D Deterministic Ground Motion Simulations in Central Italy

Description: 

Starting on August 24, 2016, with the M6.2 Amatrice earthquake, a sequence of earthquakes has resulted in numerous casualties and significant damage to buildings in central Italy. Following the Amatrice mainshock (Mw6.2), the Visso (Mw5.9) and Norcia (Mw6.5) events occurred two months later. The seismic activity has been meticulously recorded by a dense network of strong motion stations, with over 40 stations located within 50 km from the fault rupture. Considering the persistent seismic activity in this region, our objective was to develop a tool using a fully deterministic 3D approach to calculate strong ground motions at higher frequencies, intended for use in seismic hazards and engineering applications. We also examined the impact of the source rupture model in the near-source area. We tested an end-to-end modeling capability for strong ground motion simulations, utilizing the extensive recorded data and predictions from regional Ground Motion Models (GMMs). The simulations were conducted in the frequency range of 0-3Hz and 0-5Hz using a physics-based deterministic technique to model earthquake rupture and elastic wave propagation for the Amatrice and Norcia earthquakes. We employed SW4, a finite difference code designed to use a topography-conforming curvilinear mesh for modeling surface topography with high numerical accuracy. Incorporating several rupture scenarios, our simulations demonstrated a direct correlation between the pattern of near-fault ground motion amplification and the slip distribution over the fault. We found that large slip patches have a pronounced impact not only on the intensity of ground motion but also on 𝛔, the inter-event variability of the PGV. In our simulations, ground motions computed with and without surface topography showed an average PGV that is 30% higher for models incorporating surface topography in the case of Norcia event. We believe that our results provide a valuable framework for understanding the physical parameters and how they contribute to the amplitudes of ground motions observed during earthquakes in Central Italy.

Session: Numerical Modeling in Seismology: Developments and Applications - II

Type: Oral

Date: 5/1/2024

Presentation Time: 11:30 AM (local time)

Presenting Author: Aybige

Student Presenter: No

Invited Presentation: 

Authors