Evaluating Alternative Approaches to Model Local Site Effects in Physics-Based Ground-Motion Simulations: Insights From Small-Magnitude Earthquakes Recorded in Canterbury, New Zealand
Description:
One of the current challenges in physics-based ground-motion simulations is to refine the modeling of local site effects. These effects require a finer spatial resolution in the material modeling than that generally considered in regional-scale simulations. Because of this, empirical amplification factors are typically applied to capture these unmodeled phenomena. The ergodic nature of this approach suggests that there is room for improvement. In this study, the predictive capability of simulations is evaluated using alternative methods for capturing local site effects. In addition to the conventional empirical approach, two methods are examined that allow for more site-specific information to be incorporated: the square-root impedance method and the 1D time domain site-response analysis. The three approaches are tested using 1000+ observed ground motions from 150+ small-magnitude events (3.5 ≤ Mw ≤ 5.0), recorded at 20 strong-motion stations in the Canterbury, New Zealand, region. These 20 well-characterized sites represent a wide range of soil conditions, including stiff gravels with Vs30 values greater than 500 m/s, and sand and silt deposits with Vs30 values less than 200 m/s. Multiple intensity measures are computed and prediction residuals are partitioned using mixed-effects regression to rigorously assess the relative performance of the different approaches considered. The results indicate that the benefit of using more sophisticated methods is highly dependent on the characteristics of the site. Key site parameters and trends are identified and discussed in light of the assumptions and limitations of each approach.
Session: Site-specific Modeling of Seismic Ground Response: Are We Quantitative Enough to Predict?
Type: Oral
Date: 4/19/2023
Presentation Time: 10:30 AM (local time)
Presenting Author: Felipe Kuncar
Student Presenter: Yes
Invited Presentation:
Authors
Felipe Kuncar Presenting Author Corresponding Author felipe.kuncar@pg.canterbury.ac.nz University of Canterbury |
Brendon Bradley brendon.bradley@canterbury.ac.nz University of Canterbury |
Christopher de la Torre christopher.delatorre@canterbury.ac.nz University of Canterbury |
Robin Lee robin.lee@canterbury.ac.nz University of Canterbury |
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Evaluating Alternative Approaches to Model Local Site Effects in Physics-Based Ground-Motion Simulations: Insights From Small-Magnitude Earthquakes Recorded in Canterbury, New Zealand
Category
Site-specific Modeling of Seismic Ground Response: Are We Quantitative Enough to Predict?