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Eugene -Springfield Area Natural Hazards Mitigation Plan 2. Hazard Descriptions The Cascadia Subduction Zone is a 620-mile fault line off the coast of Northern California, Oregon, Washington, and Southern British Columbia. When the fault moves, causing an earthquake, it is called a `rupture." The CSZ does not always rupture along its entire length. Research suggests, over the last 10,000 years the entire fault has ruptured 20 times with a magnitude 9.0 or larger. Three quarters of the fault has ruptured 2 to 3 times producing an earthquake between 8.8 and 8.5 magnitudes. The southern portion has ruptured 19 times producing earthquakes between a magnitude 7.6 and 8.5.17 (Figure 2-3 and 2-4) Native American oral records and geologic evidence has shown the most recent Cascadia Subduction Zone (CSZ) earthquake occurred in January 1700 with an approximate magnitude of 9.0. The earthquake generated a tsunami striking Oregon, Washington, and Japan. Native American villages along the Oregon coast were destroyed. There are no known reports of structural damage from earthquakes occurring or felt in the Eugene -Springfield area in recent history. A map of local historic earthquakes is included in Section 3, within the hazard maps. Since November 2014 there have been three smaller crustal earthquakes in the Eugene and Springfield area. These incidents occurred on: • 11/12/2014 — 14 Km East of Coburg, Oregon —Magnitude 2.6 • 01/12/2015 — 13 Km East of Coburg, Oregon —Magnitude 2.6 • 07/04/2015 — 15 Km East Northeast of Springfield, Oregon — Magnitude 4.8 Even though no major damages were reported for these incidents, they are a reminder a CSZ earthquake is not the only threat the area faces. Due to the potential severity of a CSZ earthquake, it is the goal of the Multi -jurisdictional NHMP partners to prepare for, and mitigate the risks of, such an incident. By doing this, the Cities of Eugene and Springfield will not only be prepared for a major earthquake from the Cascadia Fault, but also from those closer and more centrally located. 11 United States. Oregon Department of Geology and Mineral Industries (DOGAMI). Cascadia Earthquake Facts: What You Need to Know. Slide 15-16. Accessed November 2017. http://slideplayer.com/slide/3475601/. 2-8 January 2020