The 2014 Orkney earthquake (M5.5) ruptured an ultramafic lamprophyre dike at 3.5-7 km depths in the West Rand Group (WRG) beneath Moab Khotsong mine. Deep development of the mine enables PROTEA to drill from a site at 3 km depth to the nucleation zone, ultimately the hypocenter, of the Orkney earthquake to elucidate spatial variations of frictional properties, stress state, pore pressure, and lithology along the source fault for better understanding of nucleation, propagation and termination of an earthquake.
PROTEA will drill though a substantial thickness of the WRG to systematically investigate the variation of host rock lithology associated with the dike-sill complex and its impact on the alteration of the lamprophyre dike. PROTEA will also conduct a pre-drilling seismic site survey and post-drilling seismic monitoring using up-to-date techniques. The finer structure of the dike-sill complex will elucidate its role in an extensional tectonic event such as supercontinent breakup.

PROTEA is the successor project to DSEIS, which successfully probed metamorphic minerals in an altered ultramafic dike that hosted the aftershocks of an M5.5 earthquake from a depth of 2.9 km.

KEYWORDS: Africa, South Africa, Earthquake Rupture, Deep Biosphere, Greenschist Metamorphism, In-situ Stress