The concept of social vulnerability is theoretically framed by a multi-disciplinary litany of case studies and research on specific hazard events, their impacts, and outcomes. Social vulnerability to hazards refers specifically to a lack of ability for individuals and communities to adequately prepare for, respond to, and rebound from environmental hazards. The science of vulnerability is relatively recent, but theoretical links between pre-event socio-economics and general adverse outcomes date back decades. One of the first operational measures of social vulnerability, Maloney’s (1973) Social Vulnerability of Indianapolis linked underlying social characteristics with adverse health outcomes. Subsequently, scholars at the University of South Carolina and the University of Central Florida have driven development of vulnerability science, empirical measurement of social vulnerability, and use of social vulnerability metrics for decision making, planning, and all phases of emergency management practice.


SoVI® - USC’s Social Vulnerability Index

USC’s Social Vulnerability Index (SoVI®) measures the social vulnerability of U.S. counties to environmental hazards. The index is a comparative metric that facilitates the examination of the differences in social vulnerability among counties. SoVI® is a valuable tool for policy makers and practitioners because it graphically illustrates the geographic variation in social vulnerability. It shows where there is uneven capacity for preparedness and response and where resources might be used most effectively to reduce the pre-existing vulnerability. SoVI® also is useful as an indicator in determining the differential recovery from disasters using empirically-based information. The index synthesizes 27 socioeconomic variables, which the research literature suggests contribute to reduction in a community’s ability to prepare for, respond to, and recover from hazards. SoVI® data sources include primarily those from the United States Census Bureau. Learn more about SoVI® by visiting

See what goes into producing a SoVI® analysis!

SoVI® Publications

SVI - CDC’s Social Vulnerability Index

CDC’s Social Vulnerability Index (SVI) refers to the resilience of communities when confronted by external stresses on human health, stresses such as natural or human-caused disasters, or disease outbreaks. Reducing social vulnerability can decrease both human suffering and economic loss. ATSDR's Social Vulnerability Index uses U.S. census variables at tract level to help local officials identify communities that may need support in preparing for hazards, or recovering from disaster.  Learn more about SVI by visting

SVI Publications


Utilizing a Geography as Human Ecology Approach, this method for assessing vulnerability in spatial terms uses a smaller set of social indicators (Population, Housing Units, Females, Non-White, Age under 18, Age over 65, Mean house value, and number of mobile homes). Read the Georgetown Paper.

Georgetown Publications

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Research over the past two decades from epidemiology and public health has investigated the link between health and social vulnerability, drawing ties from the social science literature to identify the social characteristics of populations at highest health risk based on access to medical resources (Aday, 1994 and 2001Aday, L. A. (2001). At risk in America. The Health and Health Care Needs of Vulnerable Populations in the United States, 2001.). These commonly cited social characteristics that correlate with health care access include social status, social capital, and human capital; showing unmistakable parity with those social indicators introduced by the social vulnerability literature in the previous section. Several researchers, however, make a clear distinction between health risk and health need (Aday, 1994 and 2001; Morath, 2010). While the social indicators of health risk help to identify sensitive populations, the indicators of health need identify individuals and communities with inherent medical vulnerability, independent of ancillary factors. While the concept of medical vulnerability is relatively new in the field of hazards research, it is tenured in a long-standing tradition combining concepts of public and environmental health, quality of life, health equity, medical surge, and other place-based models of community and family health. Based on the epidemiology and disaster surveillance literature, Morath’s (2010) investigation of medical vulnerability to disasters identifies three dimensions that contribute to a potential for harm: individual medical needs, community healthcare access, and health system capability. These dimensions are derived not only from direct disaster impacts on the exposed population, but also from impacts on the healthcare system that include the interruption of key medical services.


A scaled down, county level, version of the Environmental Vulnerability Index for the natural environment developed by the South Pacific Applied Geoscience Commission (SOPAC), the United Nations Environment Programme (UNEP) and their partners. The downscaled index is designed to be used with economic and social vulnerability indices to provide insights into the processes that can negatively influence the sustainable development across the United States.


Download the FEMA payout data comparison chart

Note: Data figures have been pulled from FEMA public website and may contain incongrunet comparison of IA‐ Applications Approved to Total Individual & Households Program ‐ Dollars Approved. This chart is meant only to illustrate the difference between estimated payout rates in as compared accross historical storms and other similar disaster events.