Index method for evaluation of seismic risks in petrochemical plants

An account is given of an extremely simple index method devised for the expeditious evaluation of seismic risks in petrochemical plants. A small number of parameter values are used for the quick identifcation of structures most vulnerable to earthquake shocks, and the definition of a seismic risk index. This ranges from 0 to 1000 and is calculated as the addiction of four factors, namely the nature of the substance contained in a structure (I1), the maximum mass that could be released in the event of an accident (I2), the geological features of the soil on which the structure stands (I4), and its type and the way it has been built (I3). R = 500 is chosen as the set point (cut-off value). Structures with R > 600 are thus to be regarded as at risk and should be checked.