The aim of this study is to show the effect of geological factors in predicting the level of blast-induced ground vibrations. The site-specific character of ground must be involved in the prediction models especially if the ground conditions have a variable character like in this case. But in a blasting environment, this is only possible by using an empirical way. Towards this aim, an in-situ experimental study in a highly jointed sandstone quarry was carried out to incorporate the variable conditions into the prediction models. Therefore, 60 shots were organized and their ground vibrations monitored in two different directions to compare the results. These shots were normal production shots involving the true technological properties as well as geological properties into the prediction model. Based on these, the empirical relations between particle velocity, the amount of explosive and distance have been developed. The results show that the performances of these estimations depend on the site-specific character of these empirical relations. The best prediction was obtained with only 2.08% error level provided that the true technological and geological properties are involved. (C) 2007 Elsevier Ltd. All rights reserved.