MOMENT MAGNITUDE ESTIMATION FOR LIQUEFACTION ASSESSMENT IN WESTERN TÜRKİYE

Abstract

Repeated static or dynamic loading causes an increase in pore water pressure within soils, leading to a significant reduction in strength and stiffness, which results in liquefaction. Therefore, accurate estimation of seismic demand is crucial in liquefaction potential assessments. Seismic demand is represented by the cyclic stress ratio (CSR), which depends on moment magnitude and ground motion parameters. In this study, different approaches to moment magnitude (Mw) were examined to determine the most suitable Mw for use in liquefaction assessments in Western Türkiye and a suitable approach was proposed based on the results obtained. Four methods are considered: characteristic magnitude (Mchar), deaggregation-based magnitude (Mdeag), fault contribution-based magnitude (Mfault) and liquefaction hazard-based magnitude (Mliq). Liquefaction triggering was assessed using a simplified procedure proposed by Youd et al. (2001). In addition to the classical liquefaction analysis proposed by Youd et al. (2001), an assessment was performed by normalizing the CSR values with the magnitude scaling factor (MSF) to better assess the effect of moment magnitude. The results show that the choice of moment magnitude significantly affects the seismic demand and thus the estimated liquefaction potential.