This research provides two probabilistic and deterministic methods to assess the liquefaction potential based on the piezocone (CPTu), and then a procedure is proposed to develop the seismic fragility curves of soil liquefaction. For this purpose, a reliable liquefaction case history dataset based on CPT and CPTu tests is compiled. Next, a deterministic correlation of the liquefaction potential is proposed by the use of the Group Method of Data Handling type neural network optimized with genetic algorithms. Data mining techniques are then used to compare the results of the various models, including the proposed deterministic model. The results demonstrate that an improvement in statistical measures of performance of the proposed model has been achieved. Through this study, a sensitivity analysis is carried out to clarify the more properties of the proposed method. Finally, a new probabilistic function is expanded based on the results of the deterministic approach. The developed probabilistic function is utilized as a proper tool to evaluate the fragility curves of liquefaction occurrence.