Vulnerability may be defined as the ability of a system to continue to function when exposed to undesirable events, and resilience as its ability to resume its operations or mission after the event has occurred.

Vulnerability within logistics chains may be defined as: The properties of a logistics chain; its premises, facilities, handling and transportation equipment, inter- and intra-organizational construction, including contracts and incentives, human resources, human organization and all its software, hardware, and net-ware, that may weaken or limit its ability to endure threats and survive accidental events that originate both within and outside the boundaries of the logistics chain.Vulnerability is thus a concept that may be used to characterize a logistics system’s lack of robustness or resilience with respect to various threats that originate both within and outside the system’s boundaries.

A system is said to be robust, or resilient, with respect to a threat if the threat is unable to have any ‘lethal’ effects on the system. We can define robustness as ‘a system’s ability to resist an accidental event and return to do its intended mission and retain the same stable situation as before the accidental event’. Resilience may be defined as a system’s ability to return to ‘a new stable situation after an accidental event’. The key difference is that a robust system will retain its system intact, while a resilient system has to adapt to regain a new stable position. As such, resilience is an adaptive concept as compared to robustness, and for the purpose of this research on vulnerability in maritime logistics chains, the resilience concept will be used.  The question is how to engineer resilience into maritime logistics chains, given the vulnerability of different maritime logistics chains?

Related concepts: Threat: A stable, latent, adverse factor which may manifest itself in an accidental event. Risk: Product of the frequency, probability or likelihood of occurrence and the consequences of a specified hazardous event. Damage tolerance: A measure of the robustness of a system with respect to specific damage, i.e. the reduction in reliability of a system that has suffered specific damage but has not failed.