Seismically active areas exist within Oregon. The seismic history of Oregon is too short to be used as an accurate predictor of earthquake size, number, and distribution. Continual monitoring of earthquakes by seismograph stations during the next several decades should provide a more accurate estimate of the seismicity of Oregon. To provide adequate and accurate coverage additional seismograph stations are needed, particularly in southeastern Oregon. Rapid urbanization of the Willamette Valley and extensive public works planned for other areas of Oregon make it imperative that the stabilities of the areas be known. Specialized equipment such as portable microearthquake seismometer arrays, which have been developed to assist in local immediate problems, can accurately map active fault zones. In addition, they can locate active zones of continuing deformation which exist without producing the larger release of elastic strain energy of felt earthquakes. Studies of both historical and concurrent seismicity of an area should be of paramount importance when considering potential sites for nuclear generating stations or large construction projects such as dams, airports, large office buildings, and housing developments.