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WITHDRAWN Physics-based Numerical Modeling of Site-specific Amplification in Ground Motions: A Case Study of Wellington Basin

Description: 

WITHDRAWN The amplification effect of site-specific near-surface velocity structure plays a crucial role in modulating ground shaking level, and in turn, contributes to seismic risk. However, the general understanding of this effect is limited, owing to complex 3D geological structures and the influence of coseismic source dynamics on-site response (Olsen, 2000). In this study, we use physics-based simulations of ground motion to investigate fundamental characteristics of the regional seismic response that may not be easily analyzed using regional seismic recordings.

We develop numerical models for Wellington City, which is a seismically active area with multiple active crustal faults and the Hikurangi Subduction Zone beneath it. This unique geological setting requires investigating potential earthquake ruptures and their effects on ground shaking levels. Several geological and geotechnical surveys have provided valuable knowledge about high-resolution topography, shallow structures, and fault networks (Hill et al. 2022). We focus on simulating ground motions using either kinematic sources or spontaneous coseismic ruptures. Key aspects of our study include (1) incorporation of 3D fault geometry and complex ruptures of multiple faults, (2) utilization of regional 3D basin structure, (3) development of peak ground motion maps, and (4) evaluation of the impacts of regional topography, seismic attenuation, and 3D geological models on the ground motion levels.

By studying the dynamic earthquake source process, its interaction with regional geological structures, and its impact on site amplification, we combine advanced numerical simulations with regional geodetic, geological, and seismological records. Based on the simulated seismic scenarios of the regional earthquakes, we aim to advance our knowledge of future ground shaking levels in the city and to provide general theoretical references to improve empirical ground motion models, and consequently, seismic hazard analysis.

Session: Physics-Based Ground Motion Modeling [Poster Session]

Type: Poster

Date: 5/3/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Duo

Student Presenter: No

Invited Presentation: 

Authors