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Geology, Soils, and Seismic Conditions <br />Significant Adverse Impacts <br />All Development Alternatives <br />The Eugene/Springfield area has been shown to be at least partially susceptible to seismic <br />activity, including ground motion amplification. The amount of earthquake damage that any <br />particular area would experience depends on its distance from the earthquake epicenter, local soil <br />conditions, and types of construction. However, while the large Scott Mills earthquake (5.5 to <br />6.0 on the Richter scale) caused significant damage to many buildings and structures in the <br />Portland area, modern buildings constructed with seismic zone 3 design were not damaged by <br />that earthquake. According to Oregon Department of Geology and Mineral Industries, new <br />buildings that are designed and constructed to meet the seismic zone 3 standards should not pose <br />a life or safety threat to their occupants in the event of the larger earthquakes now believed <br />possible to occur in the Eugene/Springfield area. <br />The proposed federal courthouse would be built following the Uniform Building Code seismic <br />zone 3 design with consideration of the Oregon Structural Specialty Code. Despite medium <br />susceptibility of the alternative sites to earthquake damage, no significant seismic impacts on the <br />courthouse structure would be expected to occur. <br />No-Action Alternative <br />If the proposed facility is not constructed, no additional seismic or geological impacts are <br />expected. The existing federal building/courthouse would continue to have some susceptibility <br />to seismic activity based on its existing structural design. <br />Potential Mitigation Measures <br />Provided that the proposed facility is designed and built using at least Uniform Building Code <br />seismic zone 3 design specifications with consideration of the Oregon Structural Specialty Code, <br />no further mitigation would be required. Site-specific engineering and geotechnical analyses <br />would be conducted, however, to ensure the adequacy and stability of the local soils. <br />Significant Unavoidable Adverse Impacts <br />No significant unavoidable adverse seismic or geological impacts would be expected. <br />New Federal Courthouse 43 Final EIS <br />i <br />