GIRS-2024-02: Ground motion intensity measures at liquefaction field case history sites

By: Renmin Pretell, Scott J. Brandenberg, and Jonathan P. Stewart
DOI: 10.34948/N35K59

Abstract: The state of practice for assessing liquefaction triggering relies on semi-empirical models that use the peak ground acceleration (PGA) at the ground surface and the earthquake magnitude (M) to represent the seismic demand leading to liquefaction or lack thereof. PGAs at liquefaction case history sites from past earthquakes have often been taken as equal to the PGA at the nearest seismic station, sometimes with one-dimensional (1D) ground response analyses to account for differences in site effects. When a seismic station was unavailable, ground motion models (GMMs) or judgment were used. These traditional approaches fail to account for one or more of the following: (1) The differences in path effects between the liquefaction site and the nearest ground motion recording, (2) the differences in site condition between ground motion and liquefaction sites, with the exception of some past studies using 1D ground response analyses or ground motion models, and (3) the spatial correlation of PGA. Furthermore, ground motion intensity measures (IMs) other than PGA could be more efficient for predicting liquefaction triggering and consequences, but alternative ground motion IMs are unavailable in liquefaction case history databases.

(full abstract available in the report)