Equivalent Magnitude Scale for Natural Hazards

Abstract:

Within a multi-hazard context, especially when compound and cascading natural hazard events are considered, comparison of frequencies, magnitudes, intensities, and other properties of different types of natural hazards is imperative for facilitating hazard management activities such as resource allocation both for emergency response and for long-term planning and adaptation. Focusing on the expected adverse impacts of hazard events, emergency managers, decision makers, and local and regional government officials may find it difficult to compare hazard properties of different hazard types without sufficient academic recommendation and assistance. Limited amount of literature on this issue of multi-hazard comparison indicates a strong need for scholarly exploration in a new field called hazard equivalency. In this presentation, the authors propose the concept of hazard equivalency with a demonstration of computation of equivalent magnitude scale (EMS) for natural hazards. The EMS is computed with regression models to represent the magnitude of a hazard event, indicating the extent of potential damage the event may incur. The regression models are calibrated with historical records on adverse impacts of natural hazard events such as earthquakes, floods, tornadoes, and tropical cyclones. The derived EMS can be used as a benchmark measure for quantifying and studying vulnerability and resilience with a multi-hazard approach. It may also be applied to enhance hazard communication to convey the hazard information equivalent to magnitude scales such as earthquake Richter magnitude, tornado peak Enhanced Fujita scale, and tropical cyclone peak Saffir-Simpson wind scale. The proposed concept of hazard equivalency and EMS may also provide foundational knowledge and modeling tools for further studying compound and cascading natural hazard events.