  Fatal crush conditions occur in crowds with tragic frequency. Event
organisers and architects are often criticised for failing to consider the
causes and implications of crush, but the reality is that the prediction and
mitigation of such conditions offers a significant technical challenge. Full
treatment of physical force within crowd simulations is precise but
computationally expensive; the more common method of human interpretation of
results is computationally "cheap" but subjective and time-consuming. In this
paper we propose an alternative method for the analysis of crowd behaviour,
which uses information theory to measure crowd disorder. We show how this
technique may be easily incorporated into an existing simulation framework, and
validate it against an historical event. Our results show that this method
offers an effective and efficient route towards automatic detection of crush.
