Hard Rock Underground Mining

OPERATION

A permanent underground installation of seismometers (combination of the seismic sensor and data acquisition unit) communicates with the central computer located on surface for real-time seismic monitoring of the rock mass. A GPS timing module is used so that recorded seismic data may be integrated with seismic data from another nearby IMS system for information about regional seismic events.

COMMUNICATIONS

Multiple netADC units are be linked to a seismic processor via Ethernet cable. The seismic processor communicates with the central computer on surface using DSL protocol. This is a cost effective approach as it uses inexpensive 2-core twisted-pair copper cable to communicate over long distances with high data rates.

Alternatively, if fiber optic lines have been installed and a reliable link to surface is possible, then netADC’s can be linked directly to the central computer for continuous streaming of waveforms over Ethernet.

Any number of seismometers can be supported by a IMS seismic network.

SENSORS

Typically our sensors are permanently installed into boreholes. This ensures the best signal quality as the sensors are outside the fracture zone surrounding a tunnel.

A netADC data acquisition unit can monitor up to 8 seismic signals, in any combination of uni-, bi- or tri-axial seismic sensors. Seismic processors can be customized to handle any number of netADCs, meaning that a single seismic processor can monitor and process seismic channels from multiple netADC’s. Geophones and accelerometers (piezoelectric and Force-Balance) are currently supported.

SEISMIC DATA PROCESSING & INTERPRETATION

The seismograms of every seismic event that triggers multiple stations are transmitted to the central computer. The seismic event is automatically processed and seismic source parameters including the location, time, radiated seismic energy and co-seismic inelastic deformation are automatically calculated. This data is confirmed later by manual processing with the software packages Trace running on either Microsoft Windows or Linux computer. Spatial, temporal and source parameter patterns may then be detected and analysed using the interpretation package Vantage.