NEW MAP OF ACTIVE FAULTS IN CENTRAL AND EASTERN OREGON

We have updated our map of active faults east of the Cascades as part of a larger effort to produce current digital maps of active faults in the Pacific Northwest. The new map is derived from the active fault map first made by Pezzopane, Nakata and Weldon (1992) that is reproduced in essentially all subsequent compilations of active faults of Oregon. Improvements in the new map include: a linked ArcInfo map and reference database, more precise locations of the previously recognized active faults on 100K shaded relief quadrangles generated from the current USGS 30m DEM, more uniform coverage and many newly recognized active faults, and a new category of "possibly" active faults that share characteristics with known active faults, but have not been studied enough to assess their activity. The distribution of active faults has not changed substantially from the original Pezzopane et al. map. Most faults occur in the south-central, Basin and Range/backarc portion of the State in zones consisting of numerous short faults with similar rates, ages, and styles of movement. There is also a strong correlation of active faulting with the most active volcanic centers including Newberry and Crater Lake.