A review of the research into the relations between hazards in multi-hazard risk analysis

With the development of disaster-risk research, it has been found that many areas are prone to the simultaneous occurrence of natural disasters and technological accidents. Such events are known as “multi-hazard.” Increasing attention has been paid to multi-hazard risk, and the theory and methods of multi-hazard risk analysis have been put forward and applied in some areas. Compared with single-hazard risk analysis, multi-hazard risk analysis is more complex and challenging. Researchers typically focus on the characteristics of specific multi-hazard scenarios. However, when multiple hazards occur simultaneously, the relationship between them may be complex. At present, there are still many confusing descriptions of the relationship between hazards, and there are also differences in the research methods for different multi-hazard scenarios. This paper clarifies the relationship between hazards in multi-hazard scenarios by dividing them into three categories: mutually amplified hazards, mutually exclusive hazards, and non-influential hazards. A series of risk analysis methods have been reviewed for different hazard relationships (e.g., Natech events, human-induced hazards, disaster chains, the domino effect, and concurrent hazards), and possible challenges and solutions have been put forward.