Domino effect accident is an accident in which a primary undesired event in an installation sequentially or simultaneously triggers one or more secondary undesired events in nearby installations, leading to secondary and even higher-order accidents, resulting in the overall consequences more severe than those of the primary event. Due to the escalation of accidents, domino effect accident is indeed a chain of accidents. The entire accident escalation process is similar to the mechanical effect of a falling row of dominoes, so it is called a domino effect accident or Knock-on accident. Domino effect accidents are an important safety issue in the process industry in which a lot of hazardous materials are stored, transported, and processed via storage tanks, pipes and process facilities, etc. These hazardous materials may induce poisoning, fire, and explosion when a loss of containment occurs. Fire and explosion within an installation may escalate to other installations by hazardous physical effects such as heat radiation, overpressure, and fragments, etc. The characteristics of domino effect accidents Domino effect accidents are different from general accidents in which the accident in installations does not spatially or/and temporally propagate to other installations. The consequences of domino effects are more severe than the primary event and there should be at least one secondary event. Besides, the escalation of accidents is caused by the physical effects induced by primary events. In domino effect accidents, the physical effects are defined as escalation vector. Domino effect accidents mainly consist of three elements: the primary scenario, the escalation vectors, and one or more secondary accidents. Primary scenarios The primary scenarios include flash fire, pool fire, jet fire, fireball, Boiling liquid expanding vapor explosion (BLEVE), confined explosion (CE), mechanical explosion (ME) and vapor cloud explosion (VCE). Normally, there is only one primary event such as a tank fire in a gasoline storage farm. In terms of the primary events caused by intentional attacks or natural disasters, multi-primary events may occur. In that case, it may be very difficult to prevent the escalation of domino effects due to the synergistic effects caused by multiple hazardous events. For example, an earthquake may lead to multiple failures of hazardous installations in chemical industrial areas and induce the damage of other critical infrastructures, making the prevention of domino effect accidents more difficult than domino effects caused by accidental events. Escalation vectors The escalation vectors are the hazardous effects caused by accident scenarios