A volume of approximately 1000 x 1500 x 1000 m within the eastern wall of Chuquicamata open pit mine is monitored by a 36-channel microseismic system that includes 9 triaxial and 9 uniaxial 15 Hz omnidirectional geophones. A total of 886 seismic events with moment magnitudes between -1.2 and 1.4 have been recorded and located to an average accuracy of 28 m from mid December 2006 to end March 2007. Frequency-magnitude distribution exhibits a b-value of 1.3, suggesting the failure process is characterized by a three- rather than two-dimensional behaviour within the rockmass.