In-situ investigation of site liquefaction and liquefaction-induced damages triggered by two strong Türkiye earthquakes on Feb. 6^th, 2023

The post-earthquake scientific investigation is one of the essentials for earthquake engineering. On the 6^th of February, 2023, two deadly earthquakes, whose magnitudes were M_w7.8 and M_w7.5, respectively, shook Southern-Central Turkey, caused significantly large casualties and tremendous economy loss. Through the in-situ site investigation, the liquefaction phenomena and related damages triggered by the two strong earthquakes were surveyed and preliminarily analyzed. The analytical results indicate: (1) The liquefactions induced by the earthquakes were significant, and distributed in a wide area, and caused severe damages to buildings; (2) the consequences of site liquefaction were observed as sand boils, lateral spread, ground subsidence and loss of site bearing capacity, which yielded damages to the residence buildings in great extent. (3) The liquefaction-induced lateral spread was observed in two investigation zones, and its distance ranged from meters to tens of meters, resulting in damage or demolishing of buildings. (4) In an investigation area of Golbasi City, tens of buildings were found subsided and tilting due to liquefaction-induced loss of soil bearing capacity. The subsidence of buildings ranged from tens of centimeters to 1~2 meters, and the tilting angles varied from several degrees to tens of degrees with the measured maximum angle of 20 degrees in tilt. Through the field survey of liquefaction triggered by the shocks and the analysis of liquefaction-induced consequences, the characteristics of liquefaction and the lessons learned are presented, and the findings are expected to be beneficial for liquefaction hazard mitigation in China.