Although high-modulus columns are widely used in both soil improvement and liquefaction mitigation, there is not much research, which validates their effects numerically. The aim of this paper is to investigate the role of high-modulus columns on liquefaction mitigation and propose an empirical and simplified formula to assess this effect. For this purpose, an intensive numerical analyses scheme has been performed. These analyses include three-dimensional, finite difference-based total stress analyses on generic soil, high-modulus column and earthquake combinations. The effect of the number, length, diameter of high-modulus columns, the replacement ratio, peak acceleration of the shaking event and soil strength has been discussed in detail. A factor, called as improvement ratio, defining the ratio of liquefaction resistance of free field to resistance of treated cases was then developed using probabilistic methods. The descriptive (input) parameters are selected based on regression analyses, and they are soil stiffness, replacement ratio, stiffness of high-modulus column and the depth of consideration. The model coefficients were estimated through maximum likelihood methodology. A satisfactory fit was achieved among improvement ratio estimations and numerical model results. A validation of the improvement ratio with a centrifuge test also is presented at the end of the paper. As the concluding remark, it is proven that the high-modulus column can be used safely to prevent liquefaction. The effects of these columns increase with increasing replacement ratio, stiffness of the column and increasing soil stiffness and not depend on the magnitude or the peak ground acceleration of the earthquake. Copyright (c) 2012 John Wiley & Sons, Ltd.