Liquefaction at two petrochemical facilities during the February 6, 2023, Kahramanmaras-Turkiye earthquake sequence

Abstract

Two petrochemical facilities, located in the Dortyol district of Hatay metropolitan city along the Mediterranean coastline in Turkiye were shaken by the February 6, 2023, M7.8 Pazarcik and M7.6 Ekinözü-Elbistan earthquakes in Kahramanmaraş. This study investigates their seismic performances from a seismic soil liquefaction engineering perspective, addressing several key aspects: the i) identification of surface manifestations of seismic soil liquefaction, including soil ejecta, ground deformations, and displacements, ii) examination of subsurface soil characteristics, iii) evaluations of soil liquefaction susceptibility and triggering, iv) analyses of post-liquefaction ground settlements, lateral deformations, and displacements, and v) comparisons of these observed outcomes with predicted results. The assessment results indicated that liquefaction triggering evaluations, based on the SPT- and CPT-based semi-empirical methods of Cetin et al. (2018) and Moss et al. (2006), respectively, were consistent with observed field manifestations of liquefaction or their absence. However, estimated settlements obtained from the liquefaction-induced volumetric settlement procedures of Tokimatsu and Seed (1984), Shamoto et al. (1998) and Cetin et al. (2009), underestimated field settlements. This underestimation was partially explained by the additional contribution of lateral spreading deformations to field settlements, which were not considered due to one-dimensional nature of these volumetric settlement assessments. Additionally, semi-empirical correlations of Hamada et al. (1986) and Youd et al. (2002) consistently overestimated observed lateral displacements. The discrepancies in settlement and lateral spreading displacements are believed to stem from the presence of liquefaction susceptible fine-grained and/or gravelly units, which may have higher residual shear strengths and/or produce higher volumetric strains than typical clean sand layers in case history sites used for developing these semi-empirical methods. The documented field performances and assessment results are hoped to contribute to further developing and refining/calibrating increasingly accurate and reliable empirical and/or analytical methods for assessing hazards related to liquefaction triggering, and liquefaction-induced ground deformations and displacements.