Soil liquefaction in seasonally frozen ground during the 2016 Mw6.6 Akto earthquake

Abstract

Soil liquefaction is a type of coseismic hydrological change triggered by earthquakes, and its occurrence results in major property damage and casualties. The dynamics of coseismic hydrological changes are not fully understood. In order to address this, we studied coseismic deformations such as liquefaction and ground fissures that occurred as a result of strong seismic activity during the 2016 Mw6.6 Akto earthquake, which took place in the interior of the Pamir Plateau in northwestern China. This paper presents a systematic survey of the frozen soil liquefaction and ground fissures caused by this earthquake. The majority of liquefaction sites near the Karaat River are located on the T1 terrace, in Bulake village, and are adjacent to the alluvial fan of the Kungai Mountain. We find that the liquefaction was caused by the original spring and coseismic ground fissure during the earthquake. Approximately 80% of the liquefaction sites are formed along the original spring in the epicenter. The maximum height of sand boils is 15 cm. The remaining 20% of the liquefaction sites are formed along the coseismic ground fissure. Our results suggest that the frozen soil layer impedes liquefied material in the lower unfrozen soil layer from reaching the surface, and the material formed from liquefaction is consequentially channeled through the primary fault and coseismic ground fissures. Liquefaction associated with the Akto earthquake demonstrates the importance of accounting for the possibility of a series of coseismic geological disasters, such as soil liquefaction and ground fissures, in areas with similar geology, altitude, and temperature.