The U.S. Geological Survey (U.S.G.S.) began to monitor microearthquake activity in the region of the Atomic Energy Commission's Hanford Reservation in south-central Washington in March 1969. The Division of Reactor Development and Technology (DRDT), of the Atomic Energy Commission (AEC), supported the operation of a network of 6 (later 7) short-period, high-gain seismograph stations (Figure 1) through June 1970. Then the Chemical Processing Division (CPD) of the AEC assumed support of the original 7-station network and added 9 additional stations (Figure 1). Some preliminary results from the 7-station network covering the period 23 March 1969 to 31 December 1969 were released in the U.S.G.S. open-file4report "Geologic Investigation of Faulting in the Hanford Region, Washington", by James W. Bingham, Clark J. Landquist, and Elmer H. Baltz. Preliminary reports on the results from the seismograph network for 1970 have been submitted to the AEC. This report covers a specific zone of microearthquake activity located near Wooded Island in the Columbia River, which flows along the east side of the Hanford Reservation (Figure 1). The data cover the period 23 March 1969 to 28 February 1971.
