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Abstract In this study, the dynamic behaviour and pore water pressure generation in a typical earth dam were investigated using the non-linear dynamic analyses results. Based on the Byrne version of the Finn’s Model, variations of pore water pressure ratio against the strength parameters of materials and also the dilatancy angle of shell material were considered. In addition, using the scaling method of applying maximum acceleration, the variations of pore water pressure ratio and liquefaction phenomenon were investigated in different maximum accelerations. The results demonstrated that excess pore pressure depends strongly on the strength parameters, dilatancy angle of materials and applied maximum acceleration. Inappropriate compaction of shell material results in severe increase in liquefaction-induced failure potential. In earth dams with appropriate compaction of materials, liquefaction probability in the dam body, is negligible even in large earthquake accelerations.