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Advancing Seismic Site Response Predictions: Integrating Vs Gradients and Vs Contrasts

Description: 

Current practices for seismic site response estimation rely on (1) ground motion models (GMMs) that use the time-averaged shear-wave velocity (V_S) in the top 30 m (V_S30) as a predictor, and (2) one-dimensional site response analyses (1D SRAs) that employ the entire V_S profile available at a given site. While 1D SRAs are generally considered more accurate, recent studies showed that 1D SRAs could carry significant model errors. This finding led us to investigate the ability of innovative site-specific parameters to advance GMM predictions of site response.
In a previous study, we demonstrated that V_S gradients, g₁₀ and g₃₀ (gradients over the upper 10m and 30 m depth, respectively), can be used as parameters to improve site response predictions at different vibration modes. In this presentation, we investigate (1) the role of velocity contrasts (VCs), including bedrock-to-soil VCs and inter-layer VCs, and (2) the consistency between the trends observed in real-world and simulation-based data. We use ground motion records collected by the California Strong Motion Instrumentation Program (CSMIP) and V_S profiles from the Shear-wave Velocity Profile Database (VSPDB). A dataset of 84 stations has been collected, representing a wide range of V_S characteristics. Ground motion records sourced from the Center for Engineering Strong Motion Data (CESMD) were processed using the gmprocess application and reviewed following state-of-the-art protocols. The ground motion processing workflow and challenges in computing V_S gradients using measured profiles will also be discussed.

Session: Challenges and Opportunities in Constraining Ground-motion Models from Physics-based Ground-motion Simulations [Poster]

Type: Poster

Date: 4/17/2025

Presentation Time: 08:00 AM (local time)

Presenting Author: Santosh

Student Presenter: Yes

Invited Presentation: 

Poster Number: 41

Authors