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Ground Motion Simulations Based on Source Slip Distribution, Fourier Amplitude and Phase Models for the Chilean Subduction Zone

Description: 

Relatively small earthquakes can be modeled using Fourier amplitude spectra to simulate surface strong motions using a point source assumption; however, large megathrust earthquakes require accounting for their finite fault modeling and the rupture’s rise-time to constrain strong ground motions. To model ground motions for earthquakes up to Mw 7.0, we developed Fourier amplitude and phase empirical models, which, coupled with a duration estimate, can accurately reproduce observed subduction interface ground motions. To model higher magnitude events (e.g., 2010 Mw 8.8 Maule, 2014 Mw 8.2 Iquique, and 2015 Mw 8.4 Illapel earthquakes), we divided the rupture surface into smaller areas that have an estimated slip and therefore a seismic moment (M₀) can be computed for each subfault. Also, using Molina et al.’s (2023) rise-time scaling relations for subduction interface earthquakes, we simulated the rupture process to add the contribution of each subfault to the strong motion simulation at each seismic station. The observed versus predicted comparison of seismic intensities for three major earthquakes in Chile (2010, 2014, and 2015) includes Fourier amplitudes, Arias intensity, bracketed duration, pseudo-spectral acceleration ordinates, PGA, and PGV. Despite the simplicity of the procedure, the simulated ground motions capture all the essential characteristics of the measured ground motions for engineering applications.

Session: Challenges and Opportunities in Constraining Ground-motion Models from Physics-based Ground-motion Simulations - I

Type: Oral

Date: 4/17/2025

Presentation Time: 09:00 AM (local time)

Presenting Author: Gonzalo

Student Presenter: No

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