Abstract
Mechanical properties of subsoil are frequently subject to temporal change and liquefaction resistance is not an exception. The experiences during the 2011 gigantic earthquake in Japan illustrated that more aged soils did not develop liquefaction. Since this effect of soil age is not explicitly accounted for by existing codes, the authors attempted to interpret cases where subsoil of known age liquefied or not liquefied during past earthquakes. It was found that liquefaction resistance increases after hundreds of years and that the increase of 40% is reasonably supposed to occur after 400 years. Further study was conducted on the mechanism of ageing in which grain dislocation was focused on.
