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Table 8.5 <br /> Historica~ Debris F~ow and Landslide Problem Areas ir~ the Eugene/Springfield ~Jetro Area <br /> <br /> Location <br /> <br /> EuQene <br /> Capital - Essex Lane <br /> Dillard Road <br /> Brooks~de Drive <br /> Cresta De Ruta <br /> Goodpasture Island Road <br /> Springfield <br /> Thurston Hills area <br /> Willamette Heights area <br /> Kelly Butte area <br /> <br />8.3 Landslide Risk Assessment for the Eugene/SpringfieM Metro Area <br /> <br />In this section, we review a methodology for estimating landslide losses due to winter <br />storm induced landslides. Winter storms with intense rainfalls are the most common <br />trigger for landslides in Oregon, including within Lane County and within the Eugene/ <br />Springfield Metro Area Area. Major storms with intense rainfall can result in numerous <br />landslides in slide-prone areas. <br /> <br />Of course, at any given slide-prone location, landslides can occur with or without <br />winter storms, but such occurrences are isolated and not likely to result in the type of <br />fairly widespread landslide effects that are possible during winter storms. Widespread <br />landslides can also be triggered by earthquakes, especially if the earthquake occurs <br />during the rainy season when soils are saturated. See Chapter 10 (Earthquakes) for <br />further commentary on earthquake-triggered landslides. <br /> <br />As with any risk assessment, we must overlay the hazard assessment (frequency and <br />severity of landslides) with the inventory exposed to the hazard (value and <br />vulnerability). The Level One risk assessment method given in the Regional All <br />Hazard Mitigation Master Plan for Benton, Lane, Lincoln, and Linn Counties (Phase <br />One, 1998) considers: <br /> <br /> 1) extent of landslide susceptible areas, <br /> 2) inventory of buildings and infrastructure in landslide susceptible areas, <br /> 3) severity of winter storm event (inches of rainfall in 24 hours), <br /> 4) percentage of landslide susceptible areas that will move and the range of <br /> movements (displacements)likely, and <br /> 5)vulnerability (amount of damage for various ranges of movement). <br /> <br />For the Eugene/Springfield Metro Area, the threat posed by landslides is significant in <br />the pockets of high hazard potential which overlap with developed areas (cf. Maps 8E, <br />8S, 8ES. Significant landslides in these areas could damage or destroy one or more <br />homes, damage utilities and roads in the area, and pose some level of life safety risk <br />for residents. <br />Public Review Draft: August 6, 2004 8-9 <br /> <br /> <br />