A detailed study of the earthquakes associated with the Rocky Mountain Arsenal disposal well is presented. Long-period surface-wave studies are used together with P-wave first motions to show that the 10 April, 9 August, and 27 November 1967 earthquakes occurred at depths of 3 to 5 km and were characterized by normal faulting along a northwest striking fault plane. A joint hypocenter relocation of 103 microearthquakes of a data set of 279 recorded between 1967 and 1968 shows a hypocenter pattern striking N50°W, with most of the events located about 5 km northwest of the disposal well at depths between 3 to 8 km. A fault plane dipping southwest is tenuously suggested by those earthquakes with depths less than 5 km. Modeling of near-field seismoscope observations lend support to the focal mechanisms derived.