## 1 Introduction  
An earthquake is a phenomenon that occurs when strain energy stored along the fault due to shearing between rocks is transformed into waves of energy. Its effects include ground rupture, landslides, fires, tsunami, floods, and soil liquefaction. Numerous research related to earthquakes has been performed in the literature, including hazard mapping or risk assessment [1, 2, 3, 4], seismic response or performance of structures and materials [5, 6], laboratory testing [7, 8, 9, 10], numerical modeling [11, 12, 13], and others. Historically, South Korea was considered as a region of moderate seismicity. During the years 1992 to 2013, earthquakes that occurred in the country did not exceed a moment magnitude (Mw) of 5.0, except the 2004 Uljin earthquake, as shown in Figure 1. However, recent earthquake events have caused some distress in the country. The 2017 Pohang earthquake, with a moment magnitude of 5.4, has caused significant infrastructure damage to 2165 private properties, 227 school buildings, and 11 bridges. In addition, widespread liquefaction was reported around the Heunghae basin at Pohang, which was the first ever reported case of liquefaction in the modern seismic history of Korea [14]. In a recent study, [PERSON] et al. [15] reported an increase in the seismicity rate, which was caused by an increase in seismic energy emissions. Due to these recent events, experts have voiced concerns that the Korean Peninsula may no longer be safe from strong shockwaves. Liquefaction is a phenomenon caused by the loss of shear strength due to effective stress reduction in saturated or partially saturated ground during seismic activity. Due to liquefaction at shallow depths, sand and water could burst out onto the ground surface (boiling phenomenon) during repeated shearing. In the case of structures that are built near coastal areas, the liquefaction of sands beneath or near these structures can also increase seepage pressures, which could result in the spreading of the generated pore water pressures into larger areas that are less susceptible to liquefaction, further increasing the risk of large-scale destruction of coastal structures such as roads, ports, and embankments, as seen in the photo in Figure 2.  
Several techniques have been developed to either prevent liquefaction from occurring or reduce its consequences on structures. Methods such as soil compaction [16; 17; 18], drain techniques [19; 20], soil mixing [21; 22], and grouting [23; 24; 25; 26] are usually performed after liquefaction potential is evaluated. The liquefaction potential of soils is often evaluated using the simplified procedure originally proposed by [PERSON] and [PERSON] [27] based on the standard penetration test (SPT), and it has been updated or extended including the development of new methods using the cone penetration test (CPT) and the Becker penetration test (BPT), as summarized by [PERSON] et al. [28]. The simplified method then gave rise to many studies related to the improvement of liquefaction assessment methods, liquefaction vulnerability assessment and mapping, and the application of liquefaction mitigation techniques. [PERSON] et al. [29] were able to recommend new probabilistic and deterministic relationships for the assessment of the likelihood of initiation of liquefaction. After the development of the stochastic models, the relevant uncertainties including measurement errors, model imperfection, statistic uncertainty, and others, were addressed. Following the 2012 Emilia-Romagna earthquake in Italy, [PERSON] and [PERSON] [30] reported  
Figure 1: Variation of earthquake magnitude in South Korea from year 1992–2019 (data obtained from weather.go.kr, accessed on 5 September 2019). Figure 2: Cracks at a port in Pohang after the 5.4 magnitude Pohang earthquake hit the city (photo by the Ministry of Oceans and Fisheries of Korea). findings from field investigations conducted in the areas affected by the earthquake.