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Assessing One-Dimensional Site Response From Single-Station Earthquake Records

Session: How Well Can We Assess Site Effects So Far? I

Type: Oral

Date: 4/20/2021

Presentation Time: 10:45 AM Pacific

Description: 

The one-dimensional (1D) site response analysis dominates engineering practice as it is based on the assumption that it can provide an unbiased estimate of site effects. In this case, epistemic uncertainty in site response mainly arises from uncertain soil properties. This approach has ruled practice for projects in which site-specific site response is assessed. However, the 1D representation of the soil column can account neither for topographic effects nor for horizontally propagating surface waves, meaning that local 2D/3D models are required at many sites at which the site response is considered to be complex. As observational evidence, we develop a classification scheme based on the variability and similarity of the horizontal Fourier spectra from earthquake recordings for grading the site response complexity. The classification is based on the surface stations of the KiK-net network in Japan for which a large number of additional information is available. We see that a large number of sites is affected by 2D/3D effects. Quantifying the epistemic uncertainty reduction using the within-event standard deviation, we see that it can be decreased by 15% accounting for 2D/3D effects.

Presenting Author: Marco Pilz

Student Presenter: No

Authors