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<br />~, ' ~; "'.. <br /> <br />oOlo:h <br /> <br />Scenario 3 - <br /> <br />A large volume of material resulting in the damming of <br />the Eagle River, <br /> <br />These scenarios are realistic in the spring of the year after an <br /> <br />unusually high precipitation period such as recently experienced. One or <br /> <br />more of the earthflows could overcome its transient stability and move <br /> <br />down into the valleys, burying the highway and railroad and damming the <br /> <br />valley, Quick calculations indicate a dam of 200 feet to be a distinct <br /> <br />possibility. (The Thistle slide formed a dam 240 feet high,) Whether <br /> <br />the Eagle River would be able to cut a channel through the slide mass as <br /> <br />it moved, or the valley would be completely blocked as at Thistle, would <br /> <br />depend on the rate of movement of the slide mass. the percentage and size <br /> <br />of boulders and consolidated rock in the slide (and, therefore. its <br /> <br />erodibility), and the amount of water then flowing in the Eagle River, <br /> <br />/ <br />\ <br /> <br />Insufficient data exists to confidently predict the most likely time <br /> <br />and magnitude of future slide movement. An unusual coincidence of <br /> <br />adverse conditions could occur and the slides could reactivate in a <br /> <br />drastic fashion, Current information prevents predicting whether the <br /> <br />time frame should be measured in months~ years, or decades; however, one <br /> <br />slide could trigger movement of other areas, Therefore. it is important <br /> <br />to examine and prepare for the range of possibilities. <br /> <br />/ <br />I <br />... <br />