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Social Vulnerability and Climate Change

In the article, “Community Variations in Social Vulnerability to Cascadia-Related Tsunamis in the U.S. Pacific Northwest,” the authors Nathan J. Wood, Christopher G. Burton and Susan L. Cutter, opine that the impacts of future tsunamis on individuals and communities in Oregon will vary widely due to socioeconomic and demographic differences.

  The science of social vulnerability gauges how “physical, social, economic and political components influence the degree to which an individual community, or system will be threatened by a particular event and their ability to mitigate those threats and recover if the event was to occur.”  Given that one of the most significant tsunami threats in the United States is likely to occur within the Cascadia subduction zone, along the Oregon coast, understanding community vulnerability is essential for planners and emergency managers in order to identify those groups who are more susceptible to loss and develop risk-reduction strategies directed toward local community needs.  It stands to reason that these same vulnerability factors should be consulted when planning for other climate change impacts such as sea level rise as well.  (Please click here to refere to a map of the Oregon coastiline, and social vulnerability.)

Social and demographic factors relevant to determining vulnerability include gender, age, employment, housing, socio-economic status, education, race, and ethnicity.  For example, a 2007 survey indicated that 45% of the residents in the City of Bandon are over 65 years of age and these older residents may have difficulty evacuating within the 30 minute window predicted between an earthquake and tsunami inundation.  Vulnerability can also be evaluated at the community level where one neighborhood may be more vulnerable if it contains high concentrations of single-parent, low-income, and poorly-educated families living near each other.  Where vulnerabilities overlap, the effects are often amplified.  By mapping areas with the greatest number of vulnerability factors and overlaying those maps with those areas subject to tsunami inundation provides some interesting results.    

The article concludes that in general, the Oregon tsunami-hazard zone contains primarily low to middle income households.  The percentage of families earning $100,000 or more in this zone is approximately half the national average whereas the percentage of individuals living in poverty here approximates the national average.  The number of individuals within the tsunami inundations zone that lack a high-school diploma is slightly less than the national average.  Low-income households and the less educated are impacted to a greater degree by disasters as they are not as likely to have structurally maintained their homes making their homes more prone to damage and they often have insufficient reserves to repair or replace their homes.

Although households within tsunami inundation zones at the Oregon coast are likely to be smaller and not contain many children, the percentage of seniors, individuals 65 years in age or older is more than double the national average.  Seniors are more likely to have mobility or health issues making relocation difficult, they are likely to be more reluctant to evacuate and are more apt to lack social and economic resources to recover.  A relatively high percentage of individuals reside in mobile homes, are recipients of social-security benefits and coastal communities retain a very low percentage of individuals maintaining full employment.  All of these factors work to increase the social vulnerability of certain areas.

The study found that although gender, race and ethnicity can contribute to social vulnerability, they do not play a big role in Oregon.  Gender-related variables are not significant and although the number of individuals classifying themselves of American Indian or Alaska Native descent is higher than the national average, the area does not maintain a high degree of racial diversity.  It is interesting to note when it comes to gender differences, women tend to have a heightened perception of risk, they are more likely to have a disaster preparedness plan, and are more likely to respond to warnings than men.  However, although not trending so in Oregon, women are also more likely to be single parents, have lower incomes, and less autonomy than men.

Notwithstanding these general trends, vulnerability scores varied widely city by city and even block by block within cities.  76% of individuals considered to have high social vulnerability come from only four incorporated cities (Seaside, Lincoln City, Waldport, and Warrenton) and the incorporated portions of two counties (Tillamook and Coos).  This suggests that there is no discernible geographic trend for where these populates are likely to locate – they reside in areas from the northern to the southern-most corners of the state.  The article finds no specific correlation between the numbers of residents considered to be highly vulnerable with the total number of residents within the tsunami hazard zone.  For example, the City of Seaside has the highest number of residents with higher levels of social vulnerability than any other city but this group only represents 9% of the in-hazard population.  The authors caution against overlooking these special needs populations that are large in numbers but represent a small fraction of those who may be impacted.  On the other extreme, communities like Astoria, Nehalem, Wheeler, Toledo and Bandon have low numbers of individuals with high social vulnerability overall but these few individuals represent a large percentage of the in-hazard population.  In these communities, emergency responders will be assisting a small, but disproportionately highly vulnerable population.  All of these impacts will be aggravated by the scale of the vulnerability and the extent and severity of the natural hazard.

Planning for and responding to climate change effects, including the increased likelihood of tsunamis, must include identifying socially vulnerable communities in a geo-spatial way and understanding how those vulnerabilities place people at risk.  By realizing that efficient and effective disaster planning cannot occur on a one-sized fits all basis, individual counties and cities must identify strategies focused not only the type of hazard but the socio-economic status of the specific population that is threatened. 

References:  Wood, Nathan J, Christopher G. Burton and Susan L. Cutter, “Community variations in social vulnerability to Cascadia-related tsunamis in the U.S. Pacific Northwest,” Natural Hazards Rev (2010) 52: 369-389. Tate, Eric, “Social Vulnerability and Natural Hazards,” University of South Carolina powerpoint;

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