[en] This report is a seismicity study of the Pacific Northwest region of the United States; it covers the period between November 1961 and August 1965. During the study, 326 epicenters (SDL events) were located by visual analysis of film records of short-period seismic data. Magnitudes for these events ranged from 1.5 to 4.2, and were computed with a method that utilized vertical component L/sub g/ motion. This method was shown to be compatible with body-wave magnitudes. These SDL events were in addition to the 302 events in the area of interest, ranging in body-wave magnitude from 3.0 to 6.5, compiled from the National Earthquake Information Service (NEIS) epicenter list. A plot of the 326 events generally shows the same geographic distribution as the plot of the NEIS events, except in Oregon, where most of the SDL events were located in the historically quiet SE quadrant of the state. Considerably more events were located in Washington and Oregon than appeared on the NEIS plot; hence, the area of interest is evidently far more active than traditionally thought. Geotech recommends that the Corps of Engineers refine locations, develop single-station location techniques, develop travel-time tables for the region, and investigate depth determinations. 7 figures, 17 tables