Resolution No. 4814 - Laserfiche WebLink

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measures which better prepare the community to respond to and recover from disasters for which physica~ mitigation measures are not possible or not economically feasible. 1.4 Key Concepts and Definitions The central concept of mitigation planning is that mitigation reduces risk. Risk is defined as the threat to people and the built environment posed by the hazards being considered. That is, risk is the potential for damages, losses and casualties arising from the impact of hazards on the built environment. The essence of mitigation planning is to identify high risk locations/situations in the Eugene/Springfield Metro Area and to evaluate ways to mitigate (reduce) the effects of future disasters on these high risk locations/situations. The level of risk at a given location, building or facility depends on the combination of hazard and exposure as shown in Figure 1.1 below. Figure 1.1 Hazard and Exposure Combine to Produce Risk HAZARD EXPOSURE RiSK Frequency Value and Threat to the and Severity + Vulnerability of = Community: of Hazard Events Inventory Peopie, Buildings and Infrastructure Risk is generally expressed in dollars (estimates of potential damages and other economic losses) and in terms of casualties (numbers of deaths and injuries). There are four key concepts that govern hazard mitigation planning: hazard, exposure, risk and mitigation. Each of these key concepts is addressed in turn. HAZARD refers to natural or anthropogenic events that may cause damages, losses or casualties (e.g., floods, winter storms, landslides, earthquakes, hazardous matedal spills, etc.). Hazards are characterized by their frequency and severity and by the geographic area affected. Each hazard is characterized differently, with appropriate parameters for the specific hazard. For example, floods may be characterized by the frequency of flooding, along with flood depth and flood velocity. Winter storms may be characterized by the amount of rainfall in a 24-hour period, by the wind speed, or by the amount of snow or ice associated with a storm. Earthquakes may be characterized by the severity and duration of ground motions and so on. A hazard event, by itself, may not result in any negative effects on a community~ For example, a flood-prone five-acre parcel may typically experience several shallow floods per year, with several feet of water expected in a 50-year flood event. However, if the parcel is wet~ands, with no structures or infrastructure, then there is no risk. That is, there is no threat to people or the built environment and the frequent Public Review Draft August 6, 2004 1-3