The study presents the testing and results of simulation modeling of surface flows caused by the results of volcanic activity. An analysis of various rheological models was carried out, with a justification for the effectiveness of the Herschel-Bulkley generalized fluid model as applied to geodynamic processes (lahars, mudflows, rockfalls, etc.). The proposed hypothesis was tested and confirmed its viability based on information about a real event – the eruption of the Chaiten volcano.