abstract
Seismic data recorded for a 7-year period at the Uinta Basin Observatory were searched for earthquakes originating near an oil field at Rangely, Colorado, 65 km ESE of the observatory. Changes in the number of earthquakes recorded per year appear to correlate with changes in the quantity of fluid injected per year. Between November 1962 and January 1970, 976 earthquakes were detected near the oil field by the UBO station; 320 earthquakes were larger than magnitude 1.
Richter local magnitudes are estimated from both S-wave and P-wave measurements; a method based on the duration of the seismic signal is used to estimate the magnitude of the larger shocks. Magnitude of the two largest shocks was 3.4 and 3.3. The total seismic energy released was 1017 ergs. During this same period, the energy used for water injection, measured at the wellhead, was 1021 ergs.
