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Teri Higgins June 30, 2016 Page 2 from approximately Yaquina Bay south to Coos Bay (i.e. due west from Eugene), he proposes a recurrence interval of 300 to 380 years. If that is the case, it is expected that some of these events to be smaller than a M9.0 expected on the average of every 500 years. For the CSZ Mw9.0 event, the Eugene area would expect peak ground accelerations (PGA) on the order of 15 to 20 percent times gravity, or about 7 in/sec peak ground velocity (PGV is another shaking intensity parameter used for pipeline evaluation). By comparison, events such as the 1994 Northridge, California Earthquake and the 1995 Kobe, Japan Earthquake produced PGAs on the order of 60 to 80 percent times gravity. The recent Napa, California Earthquake produced a PGA on the order of 50 percent times gravity. The CSZ information included on the DOGAMI Open File Report 13‐06 (O‐13‐06), and used to develop the Oregon Resilience Plan, addresses this event. Hazard mapping from O‐13‐06 used for this evaluation included: Peak Ground Velocity (PGV) Liquefaction Probability Permanent Ground Deformation (PGD) Due to Liquefaction Earthquake Induced Landslide Probability Permanent Ground Deformation (PGD) Due to Landslides Earthquakes cause shaking that can result in structural damage to facilities and buried piping. They can also cause liquefaction and associated lateral spreading, and landslides, both of which are forms of PGD. PGD is particularly damaging to buried piping. In the 1995 Kobe Earthquake, wide‐spread liquefaction and associated ground deformation was the primary cause of over 1,200 pipeline failures. In the 2011 Christchurch New Zealand earthquake, widespread liquefaction along the Avon River caused extensive damage to both water and sewer pipelines. DOGAMI mapping shows a low probability of liquefaction (0‐5%) along the Willamette and McKenzie Rivers. The probability is low for several reasons. First, the higher liquefaction susceptibility found further north along the Willamette River in Oregon was due to alluvial deposits in the backwater of the Missoula Floods. That flood backwater did not extend south as far as Eugene. Second, the alluvial deposits found along the two rivers in the Eugene area are generally too course to allow liquefaction, as the rivers are just starting to lose energy coming out of the Cascades. Finer sands are washed downstream. The mapping shows the most significant liquefaction probability (moderate, 5 – 15% probability as defined by DOGAMI) in Eugene in the hills in the southwestern, southern, and southeastern areas of the City. This liquefiable material is likely from other local sources. DOGAMI maps the moderate liquefaction probability soils overlapping with areas mapped as having high landslide susceptibility. The probabilities are taken into account when estimating the number of pipeline failures. 2020 Eugene Wastewater Master Plan Appendix A-2