Identification of the Timing of Liquefaction at a Levee Site in Japan Using a Time-Frequency Based Analysis

Earthquake-induced liquefaction phenomena are among the most damaging geotechnical effects during earthquake events. Current liquefaction triggering models are based on case histories comprising three pieces of information: (1) ground motion intensity at the site, (2) liquefaction manifestation observation (or lack thereof), and (3) co-located geotechnical field investigation data. In recent years, new case history types, characterized by the presence of liquefaction observations and co-located ground motion recording stations, were identified. The availability of such data enabled new analysis strategies based on time-frequency analyses of ground motions at liquefaction sites through the use of the Stockwell transform. This study presents the implementation of time-frequency analyses to ground motions recorded during the 2011 M9.1 Tohoku earthquake in Japan at a well-documented instrumented levee site named Yamazaki. Using this procedure, the timing of liquefaction and possible critical layers were identified, demonstrating the effectiveness of this technique in providing insights into liquefaction case histories.