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Incorporating Uncertainties Into Vs-delta Kappa_0 Corrections

Description: 

Relevant characteristics of recorded earthquake ground motions reflect the contributions of shallow and deep geologic structures at the recording station. Instrumented infrastructure (e.g., bridges or buildings) are still not common, and when available, records at these sites of interest may not correspond to desired design levels. Hence, adjustments of recorded ground motions are necessary to obtain hazard-compatible ground motions at the site of interest. While corrections for impedance and attenuation properties of near-surface materials have been proposed, uncertainty in those properties has not been explicitly quantified. The Vs-delta kappa_0 correction framework is used here to modify recorded ground motions at the ground surface and derive ground motions at the assumed reference condition at a nearby site of interest (i.e., simplified deconvolution process). This study incorporates uncertainties in shear wave velocity (Vs) and delta kappa_0 into the modification of recorded ground motions. To demonstrate our proposed approach, we use a case study based on recorded ground motions from the 2018 Anchorage earthquake and measured Vs profiles in Anchorage, Alaska. The Toro’s (1995) randomization model (i.e., Monte Carlo simulations) is applied to generate multiple synthetic Vs profiles and assess uncertainties in Vs values. A range of delta kappa_0 is also considered. The multiple synthetic Vs profiles help obtaining multiple modified ground motions using the Vs-delta kappa_0 correction framework. We find that adjusted median spectral values, in terms of spectral accelerations and displacements, at the assumed reference conditions are in agreement with recorded ground motions at a nearby downhole array and they fall within one standard deviation from median predictions from suitable ground-motion models. The proposed framework to incorporate uncertainty in Vs and delta kappa_0 provide a simplified alternative to deconvolution techniques and can expand the catalog of suitable recordings at a given site of interest.

Session: Why Ignore the Structure? Soil-structure Interaction and Site Response at Local and Regional Scales [Poster]

Type: Poster

Date: 4/17/2025

Presentation Time: 08:00 AM (local time)

Presenting Author: Jungmin

Student Presenter: Yes

Invited Presentation: 

Poster Number: 11

Authors