Basic principles of multi-risk assessment: a case study in Italy

The assessment of the impact of different catastrophic events in a given area
requires innovative approaches that allow risks comparison and that account for all the
possible risk interactions. In the common practice, the risk evaluation related to different
sources is generally done through independent analyses, adopting disparate procedures and
time–space resolutions. Such a strategy of risks evaluation has some evident major
drawbacks as, for example, it is difficult (if not impossible) to compare the risk of different
origins, and the implicit assumption of independence of the risk sources leads to neglect
possible interactions among threats and/or cascade effects. The latter may amplify the
overall risk, and potentially the multi-risk index could be higher than the simple aggre-
gation of single-risk indexes calculated considering each source as independent from the
others. In this paper, we put forward some basic principles for multi-risk assessment, and
we consider a real application to Casalnuovo municipality (Southern Italy), in which we
face the problem to make different hazards comparable, and we highlight when and how
possible interactions among different threats may become important.

FP6 European project NaRaS; FP7 European project MATRIX

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