A Community Impact Scale for Regional Disaster Planning with Transportation Disruption

Abstract

This paper proposes a simple analytical scheme and associated qualitative impact scales that capture the spatially varying effects of a regional disaster. Large-scale disasters that affect many towns and cities pose particular challenges for emergency response planning. For example, disruption to transportation systems can impede regional supply chains of critical goods, thereby exacerbating the impacts suffered locally in communities. Conventional metrics of disaster severity, such as number of casualties or intensity of ground shaking, do not adequately capture how community impacts and needs may vary across the affected region, and they do not typically consider regional transportation disruption. Using a series of impact scales, the approach in this paper captures essential attributes of three broad components related to community impacts from a regional disaster—local disaster impacts in a community, regional transportation disruption to the community, and the community’s coping capacity—and aggregates them to an overall metric of community impact. The approach can be implemented with widely varying degrees of data availability, as demonstrated in two case applications. Both cases involve an M9 Cascadia subduction zone earthquake affecting a broad region of coastal British Columbia, Canada. The first application illustrates how in a pre-event planning situation, modeled results can be used to anticipate which communities are at greatest risk, and to help prioritize mitigation and emergency response planning. The second case demonstrates how in the immediate aftermath of a disaster, the approach can be used with limited information to help prioritize response and recovery activities.