Abstract:

From 1949 through 2000, ice storm disasters cost United States businesses, municipalities, and individuals more than $80 billion, only a fifth of which was covered by insurance. These disasters primarily affected areas from New England to the Deep South. Although freezing rain is most common in northern United States, ice storms can wreak havoc in regions unprepared for slick roads during the event and the prolonged power outages that follow.

This dissertation presents the results of an impact assessment of ice storms, a review of National Weather Service warnings and communications relating to ice storms, and an analysis of the perceptions and actions of county emergency managers. The greatest effect of ice storms is power outages, which last for up to a month in the most severe cases. The risk of outage could be reduced with stronger, more consistent tree-trimming standards. Meteorologists with the National Weather Service generally issue timely messages warning about impending ice storms, and many contact government officials in advance. Even so, the quality and quantity of warnings varies greatly and common standards should be implemented. Although emergency managers are well aware of the potential for disruption from ice storms and take appropriate actions in response, more widespread use of drills should improve the managers' effectiveness. Geographically, ice storms cause longer-lasting disruption for rural areas, which also are more likely to lack resources sufficient to plan and respond to ice storms. State emergency management agencies should provide extra assistance to rural counties before, during, and after ice storms.

More generally, this dissertation extends knowledge about the benefits of risk-based versus vulnerability-based approaches to reducing the effects of hazards. Ice storms demonstrate that both approaches are necessary and valuable. While utilities, forecasters, and emergency managers can reduce the risks of problems associated with ice storms, individuals and governments must take steps to reduce societal vulnerability. While these steps are inherently more difficult (such as reducing reliance on transportation systems) or heavy-handed (such as mandating non-electrical backup systems for furnaces), they are necessary if society wants to reduce the economic losses and other disruptions that result from ice storms.