Sand liquefaction during the 2021 M 7.4 Maduo earthquake, China.

The Maduo earthquake caused a large number of sand liquefaction features to form in the surface deformation zone. Structural stress, shaking, and hydraulic fracturing, as well as animal activities, provided migration channels for the liquefied sand. Based on the different flow paths that produced the sand features, the sand liquefaction was classified into four different morphologies. The first morphology was formed by liquefied sand being ejected from the large cracks developed in the main surface rupture area. The second morphology was characterized by the en echelon distribution of sand ejected from small shear fractures developed outside of the main surface rupture zone. The third morphology was characterized by the sand below a weak layer being liquefied by vibration and hydraulic fracturing and ejected, forming independent sand cones and circular pits. The fourth morphology was characterized by mouse holes providing pathways for the eruption of liquefied sand. [ABSTRACT FROM AUTHOR]