An update of Quaternary faults of central and eastern Oregon

This publication updates previous fault maps of Oregon as a contribution to the larger U.S. Geological Survey effort to produce digital maps of active faults in the Pacific Northwest region. The new map is derived from the 1992 fault map of Pezzopane, Nakata, and Weldon that has seen wide distribution and has been reproduced in essentially all subsequent compilations of active faults of Oregon. This publication provides a substantial update of known active or suspected active faults east of the Cascades. Improvements in the new map include (1) many newly recognized active faults, (2) a linked ArcInfo map and reference database, (3) more precise locations for previously recognized faults on shaded relief quadrangles generated from USGS 30-m digital elevations models (DEM), (4) more uniform coverage resulting in more consistent grouping of the ages of active faults, and (5) a new category of "possibly" active faults that share characteristics with known active faults, but have not been studied adequately to assess their activity. The distribution of active faults has not changed substantially from the original Pezzopane, Nakata and Weldon map. Most faults occur in the south-central Basin and Range tectonic province that is located in the backarc portion of the Cascadia subduction margin. These faults occur in zones consisting of numerous short faults with similar rates, ages, and styles of movement. Many active faults strongly correlate with the most active volcanic centers of Oregon, including Newberry Craters and Crater Lake.