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The Mark at Eugene January 6, 2026 Seismic Hazard Study 10 Project No.: 2251077 Eugene, Oregon Landmark Construction, LLC HazVu website indicates a high liquefaction susceptibility in the project area (Burns et al., 2008; DOGAMI, 2018). However, the site-specific subsurface data provides a better indication of the risk at this site, and the HazVu data is intended to provide a broader assessment of possible risks. Lateral spread is a liquefaction-induced hazard, which occurs when soil or blocks of soil are displaced down slope or toward a free face (such as a riverbank) along a liquefied layer. The lateral spread hazard at this site is considered negligible due to the absence of a liquefaction hazard. Subsidence. Ground subsidence is a regional phenomenon resulting from a large magnitude CSZ earthquake. It occurs because the subduction of the oceanic crust beneath the continental crust compresses the continental crust and pushes it upward. Prior to the earthquake, the continental crust is held in this position by friction at the CSZ interface. When the earthquake occurs, that frictional bond breaks allowing the continental crust to drop. The ASCE online tsunami tool (ASCE, 2021) indicates a ground subsidence at the site of 0.44 feet for the ASCE 7-16 criteria and 0.35 feet for the ASCE 7-22 criteria. Ground subsidence cannot be mitigated. Therefore, it should be assumed the site and surrounding area could drop by up to 0.5 feet during a large magnitude CSZ earthquake. Subsidence has widespread regional effects and is not considered a site-specific hazard. Fault Rupture. The risk of fault rupture is expected to be low due to the lack of known active faulting beneath the site (Personius et al., 2003; Madin and Murray, 2006; McClaughry et al., 2010). The closest potentially active (Class A) crustal fault is the Owl Creek fault, which is ±30 miles north-northwest of the site. Tsunami / Seiche/ Earthquake-Induced Flooding. Tsunami are waves created by a large-scale displacement of the sea floor due to earthquakes, landslides, or volcanic eruptions (Priest, 1995). Tsunami inundation is not applicable to this site because Eugene is not on the Oregon Coast. Seiche (the back-and-forth oscillations of a water body during a seismic event) is also not a local hazard due to the absence of large bodies of water near the site. According to HazVu, there is no localized flood potential for the Effective FEMA 100-year flood at or near the site (DOGAMI, 2018). Earthquake-induced flooding related to the failure of other structures (e.g., dams) or shallow groundwater and subsidence does not apply to the site. Local Ground Motion Amplification. Ground motion amplification is the influence of a soil deposit on the earthquake motion. As seismic energy propagates up through the soil strata, the ground motion is typically increased (i.e., amplified) or decreased (i.e., attenuated) to some extent.