Vulnerability is the potential for harm to the community and relates to physical assets (building design and strength), social capital (community structure, trust, and family networks), and political access (ability to get government help and affect policies and decisions). Vulnerability also refers to how sensitive a population may be to a hazard or to disruptions caused by the hazard. The sensitivity can affect the ability of these populations to be resilient to disasters (NRC, 2006b; Cutter et al., 2003, 2008). Vulnerability is projected by the presence and effectiveness of measures taken to avoid or reduce the impact of the hazard through physical or structural methods (e.g., levees, floodwalls, or disaster-resistant construction) and through nonstructural actions (e.g., relocation, temporary evacuation, land-use zoning, building codes, insurance, forecasts, and early warning systems), or construction-related and nonconstruction-related methods.2
What Is Disaster Risk?
For the purpose of the report, we have adopted a broad definition of risk. The definition presented in this chapter draws common elements from among a range of existing definitions and the communities that provide them. Most definitions take into account elements of hazard (what could happen to trigger damage), exposure (what is at stake), vulnerability (the level of sensitivity to a hazard), and consequences (the impact or damage caused by the hazard). We refer to disaster risk as the potential for adverse effects from the occurrence of a particular hazardous event, which is derived from the combination of physical hazards, the exposure, and vulnerabilities (Peduzzi et al., 2009; IPCC, 2012). Similarly, we use the term disaster risk management (or simply risk management) to include the suite of social processes engaged in the design, implementation, and evaluation of strategies to improve understanding, foster disaster risk reduction, and promote improvements in preparedness, response, and recovery efforts (IPCC, 2012).
Consequences are the result of the hazard event impacting the exposure in a region or community, taking into account the degree of the community’s vulnerability. Consequences can be immediate (e.g., the loss of human lives, injuries, damaged buildings, businesses), or long term (e.g., environmental
2 The terms structural and nonstructural as they are applied in this report reflect the use of these terms in the flood, hurricane, tsunami, and to a lesser degree, the earthquake arena. Within the emergency management community, the terms are used interchangeably to describe certain mitigation measures. Although the report is consistent in its use of these terms and not outside the norm, nonstructural mitigation has a very specific meaning in engineering circles (it only refers to contents and other building elements not related to structural strength). For the purposes of this report, the committee uses the terms “structural” and “construction-related” and their opposites interchangeably.