Development of a Linear Site Amplification Model for the CEUS based on Physiographic Province and Sediment Thickness: Incorporating Lessons from Station Placement Biases
Description:
Understanding site amplification effects in the Central and Eastern United States (CEUS) enables more accurate seismic hazard assessments, informing building codes and land-use planning to mitigate earthquake risks effectively. Most current CEUS ground-motion models (GMMs) rely on the average shear-wave velocity in the upper 30 meters of the subsurface (VS30) as the primary site parameter and lack other site parameters, despite the observed and simulated influences of sediment thickness, impedance contrasts, and basin effects on ground-motion amplification. We complete residual analyses using mixed-effects regression to calculate site-to-site (S2S) residual terms from ground-motion predictions using the CEUS NGA-East GMMs. This analysis reveals strong S2S dependence on geographically defined regions within the CEUS, with additional dependence on sediment thickness. In this study, we develop a new two-parameter linear site amplification term, based on adjusted physiographic province and sediment thickness, for use with the NGA-East GMMs. When evaluated using all ground motions from earthquakes with M > 4 against the current linear amplification term, we see an average reduction in the standard deviation of site-to-site terms across all periods of 25.3%. This study also evaluates the effect of station location bias in CEUS on the site terms, first by documenting the extent of station location bias, and then by exploring sampling techniques to reduce the impact on the site amplification term. Current strong-motion station placement in the CEUS is biased toward stiffer sites with higher VS30 values, largely comprised of bedrock or shallow sediment. We hypothesize that using different sampling techniques for use in building empirical site amplification terms will aid in developing models that more accurately quantify seismic hazards at sites with higher risks of amplification.
Session: Station Installations and Site Conditions, a Quest for Improved Strong Motion Database [Poster]
Type: Poster
Date: 4/16/2025
Presentation Time: 08:00 AM (local time)
Presenting Author: Elise
Student Presenter: Yes
Invited Presentation:
Poster Number: 63
Authors
Elise Meyer Presenting Author Corresponding Author elise.meyer@tufts.edu Tufts University |
Laurie Baise laurie.baise@tufts.edu Tufts University |
Shiying Nie shiying.nie@tufts.edu Tufts University |
Weiwei Zhan weiwei.zhan@ucf.edu University of Central Florida |
James Kaklamanos KaklamanosJ@merrimack.edu Merrimack College |
Maggie Roberts maggie.roberts@tufts.edu Tufts University |
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Development of a Linear Site Amplification Model for the CEUS based on Physiographic Province and Sediment Thickness: Incorporating Lessons from Station Placement Biases
Category
Station Installations and Site Conditions, a Quest for Improved Strong Motion Database