The paradigm, using the South-Central Bronx as an example, suggests an association between the spreading burnout of the community, displacement of the poor and "evaporation of the rich," and the intensification of criminal behavior. Adapting a standard reaction/diffusion approach has produced a model of radially expanding coupled traveling-wave shock fronts in which physical decay is followed by increased pathological behavior which then contributes to the overall process and to a continuing cycle of desertification. The analysis suggests that public policies of resource allocation trigger the process of large-scale contagious physical disintegration and forced displacement which then shred the community's personal, domestic, and social networks essential to youth's proper socialization. Rather than the adoption of "triage" policies in which these urban communities are virtually abandoned, this author maintains that intervention policies must be interactive and targeted at communities during all stages of the phenomenon. 3 figures and 66 references