Strong earthquake shaking in Japan can cause saturated soil to liquefy, turning the ground into a fluid-like state that damages infrastructure [1].
This phenomenon is critical because it undermines the stability of the earth beneath cities. When the ground loses its shear strength, buildings can tilt and roads can collapse, creating significant hazards for residents and hindering emergency response efforts.
Liquefaction occurs when seismic shaking raises pore-water pressure in loose, saturated soils [1]. This process reduces the soil's strength, causing it to behave like a liquid rather than a solid [5]. The result is often ground subsidence, or the complete collapse of road surfaces [2].
Recent events have highlighted the severity of this risk. During the Jan. 1, 2024, Noto Peninsula earthquake, the region experienced severe liquefaction damage [2]. In other instances, such as shaking in Niigata City's West Ward that reached a seismic intensity of 5-upper [2], the ground became mud-like.
The physical impact on the landscape can be extreme. In some cases, liquefaction has caused a maximum ground step of one meter [3]. Other historical examples include Kumamoto City, where about 10 centimeters of subsidence was observed following a 2016 earthquake [4].
Experts identify different areas of concern depending on the scale of the disaster. While the Noto Peninsula saw the most severe recent damage, some reports suggest the South-Nankai Trough area could face the highest liquefaction danger if a massive earthquake occurs [3]. This risk extends to other affected areas, including Takaoka in Toyama [2].
“Saturated soil transforms into fluid-like mud during earthquakes.”
The prevalence of liquefaction in Japan underscores the vulnerability of coastal and alluvial plains where saturated sandy soils are common. As urban centers expand into these high-risk zones, the potential for systemic infrastructure failure increases, necessitating advanced soil stabilization and stricter building codes to prevent catastrophic structural tilts and road failures during inevitable seismic events.
