Major Earthquakes of the Pacific Northwest--Map showing earthquake epicenters across the northwestern United States in an oblique shaded relief view. Use this map to teach and learn about earthquakes in Washington and Oregon, and their relationship to cultural and physical geographic features. Includes earthquakes 5.1 magnitude and above. These earthquakes are a result of relative plate motions in the region. The oceanic Juan de Fuca plate is slowly sliding beneath the conti nental North American plate at approximately 4 cm per year. Map size 27" x 18".