Research on the mode of emergency evolution

Whether an emergency happens depends on the input of the environment and the structure of the hazard bearing body. And the spread and chain-reacting of the emergency are based on the relation between the hazard bearing body and the emergency, also the characteristic of it, besides the structure of the hazard bearing body. Because of the complexity for the occurrence and evolvement of the emergency, we give a method that the chain-reacting network of emergencies shifts to a hierarchical network, and a layer stands for one kind of disaster. In this article, we analyze the characteristic of the hierarchical networks, and explain it with an example.