Managing the risk of terrorism to interdependent infrastructure systems through the dynamic inoperability input–output model



This paper discusses the Dynamic Input–Output Inoperability Model (DIIM), which is an extension to the static Inoperability Input–Output Model (IIM). Based on Wassily Leontief's Input–Output (I–O) model, both the IIM and the DIIM analyze how the system of interdependent sectors can be adversely affected as a result of initial perturbations to other sectors through willful attacks or natural disasters. To model the industry/sector interdependencies, the DIIM uses the national and regional commodity-transaction data from the Bureau of Economic Analysis (BEA) and the Regional Input–Output Multiplier System (RIMS II). In contrast to most traditional dynamic I–O models, the DIIM introduces industry resilience coefficients to measure the efficacy of sectors' risk management options. The DIIM also incorporates the stochastic properties of a recovery through the Brownian motion, representing short-term uncertainties. The paper uses two metrics to assess the consequences to the economic sectors of attacks. The DIIM methodology is demonstrated in detail through a two-by-two economy system. This is followed by an analysis of a terrorist attack scenario, using the DIIM and the BEA/RIMS II commodity-flow data of the 59 sectors in Virginia. © 2006 Wiley Periodicals, Inc. Syst Eng 9: 241–258, 2006. DOI 10.1002/sys.20051