The Mark at Eugene January 6, 2026 <br />Seismic Hazard Study 9 Project No.: 2251077 <br />Eugene, Oregon Landmark Construction, LLC <br />DOGAMI has completed geologic and seismic hazard studies, which include Lane <br />County (Burns et al., 2008), and provides online hazard information through HazVu, <br />LiDAR, and SLIDO viewers (Black et al., 2000; DOGAMI, 2018). The above-mentioned <br />maps refer to some, but do not cover all of the seismic hazards. The reviewed <br />information is only considered a guide and does not have precedence over site-specific <br />evaluations. In the following sections, information from the available seismic hazard <br />maps is provided along with our site-specific evaluations for comparison. <br />The relative earthquake hazard is based on the combined effects of ground shaking <br />amplification and earthquake-induced landslides with a range in hazard from Zone A <br />(highest hazard) to Zone D (lowest hazard). Based on the DOGAMI mapping, the site <br />is within Zone D (lowest hazard) for the overall, relative earthquake hazard (Black et <br />al., 2000). <br />Landslides and Earthquake-Induced Landslides. LiDAR imagery shows flat, urbanized <br />slopes for most of the site (DOGAMI, 2025). The landslide mapping inventory shows <br />no historic or mapped landslides at the site (Burns et al., 2008; Calhoun et al., 2018; <br />DOGAMI, 2024). The regional landslide hazard mapping indicates low susceptibility at <br />the site and moderate to high susceptibility to deep (>15 feet) landslides are mapped <br />±0.9 miles southeast and ±1.7 miles southwest of the site (DOGAMI, 2018, 2024). <br />An area of moderate to high susceptibility for shallow (<15 feet) landslide <br />susceptibility is mapped along the east-central portion of the E 11th Avenue Alley and <br />immediately to the north which lies along the north boundary of the site. However, <br />lidar and on-site observations conclude that the shallow landslide mapping along the <br />north end of the project may not be accurate due to the flat topography and urbanized <br />surface. <br />The relative earthquake hazard maps for the Eugene-Springfield metropolitan area <br />indicate a low landslide hazard at the site (Black et al., 2000; Burns et al., 2008; <br />Calhoun et al., 2018). The site is underlain by limited fill, alluvium, and residual soil. <br />Based on the site conditions, including relatively flat topography and the absence of <br />mapped or historic landslides and instability features, we have concluded the risk of <br />landslides or earthquake-induced landslides is low. <br />Liquefaction, Settlement, and Lateral Spread. Soil liquefaction occurs when loose, <br />saturated cohesionless soil experiences a significant loss of strength during strong <br />ground shaking. The strength loss is associated with rapid densification of the soil and <br />corresponding development of high pore water pressure, which can lead to the soil <br />behaving like a viscous fluid. Liquefiable soils typically consist of saturated, loose, <br />clean sand and non-plastic to low plasticity silt with a plasticity index (PI) typically less <br />than 8. <br />Medium stiff to very stiff clay and silt with varying amount of sand (alluvium and <br />residual soil) was encountered to a maximum depth of ±81.5 feet in our borings. The <br />bulk of the foundation soil is not considered liquefiable due to the stiffness and <br />plasticity. However, some limited zones of medium dense silty sand were encountered <br />at some locations. Therefore, the risk of liquefaction impacting the building is low. The