This article aims to investigate the frequency-magnitude characteristics and lower magnitude limits of the microseismic catalog recorded with a seismic network sensitive to high frequencies at Mponeng mine, South Africa. The network, composed of one three-component accelerometer and eight acoustic emission sensors, is located at a depth of 3.5 km below the surface and covers the limited volume of approximately 300×300×300 m. The three-component accelerometer was used to estimate the moment magnitude for the limited number of 135 events (Mw ranged from -4.1 to -0.3) well recorded by the network. We use the relation between the moment magnitude estimated from accelerometer data and radiated energy/moment magnitude estimated from acoustic emission sensors to extend the catalog to lower magnitudes. The magnitude of completeness of selected spatiotemporal subsets of the catalog was estimated for: (1) an aftershock sequence of an Mw 1.9 event that occurred approximately 30 m from the network, and (2) postblasting activity during working days, located more than 80 m from the network. The data follow the Gutenberg–Richter (GR) frequency-magnitude relationship with no visible deviation from self-similar behavior of seismicity between Mw -4.4 and -1.9 for the aftershock sequence and between -3.5 and -1.5 for the postblasting dataset. We estimated the magnitude of completeness of selected subset as low as -4.3 (b=1.26) for the aftershock sequence and -3.4 (b=1.17) for the postblasting activity. Differences in magnitude of completeness are attributed to location of recorded activity and site effects.

You do not have access to this content, please speak to your institutional administrator if you feel you should have access.