Marginal cost based seismic decision: A probabilistic approach

Among various methodologies for seismic risk mitigation, the use of the marginal cost of saving a life as decision variable, proposed in the literature, does not require to assign a cost to human life. Also, optimization of resources over a territory can be profitably performed in terms of such a variable. Parameters of different type (seismic, structural, financial) enter into the analytical definition of the marginal cost of saving a life. These parameters are subject to intrinsic variability and uncertainty that are bound to affect the decision variable. This aspect was not originally taken into account systematically. The influence of the uncertainty in the various basic parameters on the decision variable is studied here. A procedure is suggested to develop constant probability of exceedance contours of the decision variable versus the design coefficient to be selected. The suggested procedure is exemplified for two regions of different seismicity.