Typology of Hazard Event Severity Metrics for Multi-Hazard Research

In the scholarly field of hazards, adverse impacts of a hazard event are interpreted as the result of interactions among hazard elements, exposure of entities of value, and vulnerability of the exposed entities. The severity of hazard elements is usually communicated as a magnitude or intensity. Such hazard event magnitude or intensity metrics correspond to the expected damages due to a hazard event given an average exposure and vulnerability. These severity metrics can be used to facilitate hazard communication and enhance emergency management. However, hazard event severity metrics for singular hazard types such as the earthquake Richter magnitude and the Saffir-Simpson hurricane wind scale cannot be readily adapted for multi-hazard comparative analyses. The first and foremost challenge to such comparative analyses is a lack of conceptual framework to systemically classify different hazard event severity metrics. In this presentation, we introduce a four-dimensional typology of hazard event severity metrics for hazard research within a multi-hazard context. The four dimensions include the spatial, temporal, applicational, and indicial dimensions. Based on a literature review on 67 existing hazard event magnitude or intensity scales for 21 singular hazard types, we demonstrate that the proposed typology can be applied to classify hazard event severity metrics. We further implement the proposed typology to two newly developed equivalent hazard event severity metrics called the Gardoni Scale and the Murphy Scale to showcase the utility of the proposed typology in facilitating quantification of hazard severity across different hazard event types.