The characteristics and mechanism of a large-scale liquefaction-triggered mudflow in loess deposit induced by the M6.2 Jishishan earthquake in Gansu province, China in 2023

Abstract

At 23:59 of December 18, 2023, a strong earthquake with a magnitude of M6.2 struck Jishishan county with a focal depth of 10km, in Gansu province, China. A large-scale liquefaction-triggered mud flow in loess deposit on the secondary terrace with a gentle slope of 2o-3.5o of the Yellow River, which buried 51 houses in two villages and killed 20 people. Based on a joint reconnaissance field investigation on the mud flow, the characteristics of extraordinary ground motion amplification and the large-scale mud flow were introduced. The mechanism of the liquefaction-triggered mud flow in loess deposit was analyzed. Lessons learned from the rare disasters were shared in this paper.