ABSTRACT
In probabilistic seismic hazard analysis, the representation of seismic sources by area zones is a standard means of data reduction. However, where the association between seismicity and geology is complex, the construction of zone geometry may become contentiously subjective, and ambiguities may be resolved through appeal to the non-scientific rule of conservatism or pragmatism. Furthermore, neither the minimal assumption of uniform seismicity within a zone, nor Euclidean geometry accord with the fractal spatial distribution of seismicity; and the magnitude insensitivity of zonation ignores the spatial extent and correlations of different sized earthquakes. An alternative procedure for area source modelling exists, based statistically on kernel estimation of the activity rate density inferred from the regional earthquake catalogue. Elucidation of this procedure is illustrated through application to Britain.
