Fuzzy risks and an updating algorithm with new observations.

Concerning the essence of risk, we suggest a new definition of risk: a scene in the future associated with some adverse incident. In many cases, risks are rather fuzzy for our perception because of the shortage of knowledge or information about the systems that determine the adverse incidents. We introduce a concept of fuzzy risk based on the new risk definition and fuzzy sets. And, in this article, we suggest a fuzzy average algorithm to update a fuzzy risk that stores all information from the original data. To illustrate the algorithm, we update a soft risk map of flood where the fuzzy risks are calculated using the interior-outer-set model.