Mechanism of Liquefaction during the 2024 Noto Peninsula Earthquake

Reference No.	2024a036
Type/Category	Grant for General Research-Short-term Joint Research
Title of Research Project	Mechanism of Liquefaction during the 2024 Noto Peninsula Earthquake
Principal Investigator	Hemanta Hazarika（Graduate School of Engineering, Kyushu University・Professor）
Research Period	July 13,2024. - July 15,2024. October 11,2024. - October 12,2024. March 22,2025. - March 24,2025.
Keyword(s) of Research Fields	2024 Noto Peninsula Earthquake, liquefaction, ground parameters, numerical analysis
Abstract for Research Report	On January 1, 2024, an earthquake of magnitude 7.6 on the Richter scale struck the Noto Peninsula. The epicentral depth of the earthquake was 16 km. In Uchinada Town, Ishikawa Prefecture, where the Japanese seismic intensity scale was under 5, large scale liquefaction was observed over a wide area. Liquefaction is a phenomenon in which saturated sandy soil near the ground surface (within about 10 m) turns from solid to liquid due to earthquake induced vibration. Uchinada town is located on a loose sedimentary sandy soil with high groundwater table and is situated on a lowland between dunes and sandbars, making the soils in the area susceptible to liquefaction. During the 1964 Niigata earthquake too, liquefaction caused many buildings to topple over, sink, or tilt. Against this background, effective stress analysis methods such as FLIP(Finite element analysis of Liquefaction Program) and LIQCA(Computer Program for Liquefaction Analysis), which are widely used in practice today, were developed in the late 1970s, enabling dynamic analysis of ground that takes liquefaction into account. However, the analysis software currently widely used in practice requires the engineer to set the liquefaction layer in advance, which means that only the phenomena assumed in advance can be analyzed. In addition, when analyzing with FLIP or LIQCA, the setting of liquefaction layer and liquefaction parameters is a technical barrier to analysis using the effective stress method, and the analytical model is set up such that only the liquefaction curve is fitted for the parameters. Therefore, a significant improvement would be achieved if the liquefaction layer and parameter settings could be set by machine learning from the data of existing analysis cases. Furthermore, there is room to examine the model itself from the basics. Currently, models based on advanced knowledge of soil mechanics are in widespread use, but it is desirable to incorporate knowledge of solids (elastic and plastic) and fluid mechanics to elucidate the mechanism of liquefaction, which is a multiphase flow, and to describe the phenomenon comprehensively. To solve these problems, this project aims to improve the existing liquefaction analysis for the Noto Peninsula Earthquake of 2024. To this end, we will conduct field investigations, determine parameters by elemental tests of soil samples collected in the field, and develop numerical models. In parallel, we will deepen the mathematical basis of the phenomena, and expect synergistic effects through collaboration between different disciplines of geotechnical engineering and mathematical sciences.
Organizing Committee Members (Workshop) Participants (Short-term Joint Usage)	Masanori Murai（Shimizu Corporation・Chief Engineer） Shiro Ohta（Kawasaki Geological Engineering Co., Ltd.・Representative Director） Yuji Michi（Yoshimitsugumi Inc.・Senior Managing Director） Takashi Fujishiro（Geodisaster Prevention Institute・CEO） Tomohiro Ishizawa（National Research Institute for Earth Science and Disaster Resilience・Principal Researcher） Tatsunori Matsumoto（Kanazawa University・Professor Emiretus）