There are numerous fault zones in Oregon. A graphical representation is available from the University of Oregon. The information below about earthquake hazards in Oregon is exerpted from an FAQ by the Oregon Department of Geology and Mineral Industries.

Q: Is there an earthquake hazard in Oregon?

A: YES! There have been no "big" earthquakes in Oregon's brief history, and there is no question that damaging earthquakes have been far less frequent in Oregon than in California or Washington. However, geologic research tells scientists that Oregon will some day experience big earthquakes, and the Scotts Mills earthquake of March 25, 1993, and the Klamath Falls earthquake of September 20, 1993, confirm the research. Because we are poorly prepared, the damage could be great. We are faced with a small chance of a great disaster.

Q: What about "The Big One"?

A: Geologic research in the last few years has shown that Oregon and Washington have probably been shaken by numerous subduction zone earthquakes during the last several thousand years. Subduction zone earthquakes occur when two great crustal plates slide past each other beneath the coast of Oregon and Washington. These earthquakes occur, on average, every 300-600 years, and the most recent was about 300 years ago. The subduction zone earthquakes were probably centered just off the coast of Oregon and Washington and may have been as large as magnitude 8 to magnitude 9. Such earthquakes would cause significant shaking and damage in much of western Oregon. Scientists cannot predict whether the next such event might occur in two years or 200 years.

Q: What parts of western Oregon are most dangerous?

A: Local earthquakes are most common in the Portland metropolitan area, northern Willamette Valley, and Klamath Falls area and may threaten the coast from Coos Bay south to Brookings. We simply do not know about the risk of local earthquakes in most other parts of Western Oregon. All of Oregon west of the Cascades is at risk from subduction-zone earthquakes. The amount of earthquake damage at any place will depend on its distance from the epicenter, local soil conditions, and types of construction.

Q: What about faults?

A: To date, no fault in western Oregon has been proven to be likely to move in an earthquake. Although many faults have been identified, we simply cannot say whether being near a fault is any more hazardous than being far from one.