Mining charter

Improving underground safety through in-house seismic expertise

Seismicity is one of the most pressing safety risks associated with deeplevel underground mining in South Africa. However, Gold Fields proactive and innovation-led approach to addressing seismicity has contributed to significant improvements in safety performance. In C2010, for example, there were no fatalities caused by fall of ground resulting from seismicity. This compares to 10 such fatalities in C2009.

In-house seismic expertise at Gold Fields

Seismic activity at all Gold Fields mines in South Africa is monitored by a team of seismologists from the Gold Fields Seismic Department at Driefontein, now part of KDC. Gold Fields is the only South African gold mining company to have committed to maintaining its own in-house seismology skills to ensure that a dedicated team is continually focused on managing seismic risk. The majority of Gold Fields peers have contracted this function out to the Institute of Mine Seismology.

When a seismic event occurs, the seismic team uses three-dimensional sensors to capture and transmit the seismic waveforms to centrally based servers at KDC for analysis. The results of this analysis – including time, location and source parameters – are then communicated back to the relevant management teams by email, SMS and local screen plotting technologies. Initial location data can be distributed to relevant managers in as little as three to five minutes after an event, helping mining teams respond rapidly to potential seismic risks.

Continuous improvement and innovation in seismic monitoring

Gold Fields Seismic Department has made major strides in improving the speed and accuracy with which seismic data can be processed and communicated. The Asynchronous Data Subscriber Line technology that the team uses can transfer seismic data across the networks up to 100 times faster than 10 years ago. Further improvements in data processing are currently ongoing. By June 2011, the system should be capable of generating data from a seismic event within nine seconds and alerting seismology and management personnel by SMS within 15 seconds.

However, the ‘holy grail’ of seismology remains the ability to forecast the timing and location of future seismic events. Gold Fields seismologists are currently investigating alternatives to the traditional time-based methods, which have been developed with little success over the last 15 years. This research is based on the principles of geo-statistical interpolation and has integrated a time based approach with geo-kriging theory. In essence, it attempts to forecast the time, position and magnitude of future seismic events based on past events. This innovative work is very much in development and is completely unique to the local mining industry.