Tarasov, BG & Ortlepp, WD 2007, 'Shock Loading-Unloading Mechanism in Rockburst Shear Fractures in Quartzite Causing Genesis of Polyhedral Sub-Particles in the Fault Gouge', in Y Potvin (ed.), Deep Mining 2007: Proceedings of the Fourth International Seminar on Deep and High Stress Mining
, Australian Centre for Geomechanics, Perth, pp. 183-192, https://doi.org/10.36487/ACG_repo/711_12
The presence of polyhedral sub-particles in dynamically-formed shear zones in quartzite is a specific
manifestation of a very complicated and still enigmatic mechanism of shear fracture development. The
existence of these sub-particles allows disclosure of one important feature of this mechanism.
Comprehensive analysis of the geometrical shape of the sub-particles gave reason to conclude that the most
plausible explanation of their formation is shock unloading taking place in the fracture zone. At the same
time the fact that a relatively minute and very strong quartz grain can be disrupted into elemental sub-
particles of approximately 25 micrometres in size must indicate the presence of enormous amount of energy
within the grain before the shock unloading. This energy can be provided, in particular, by shock loading
preceding the shock unloading.
The paper discusses a new shear rupture mechanism which can provide the combination of extreme dynamic
compressive loading followed by shock unloading within some special zones of the fault. According to this
mechanism a general fault develops as a cascade of segments triggered in series one after another.
Interaction and linkage of the segments propagating toward each other at a relative speed comparable with
shear wave speed can cause shock-like loading-unloading impulses necessary for the particle formation due
to specific structure of linkage zones.
Aste, T. and Weaire, D. (2000) The puruit of perfect packing. IoP/Bookmark. Physics. www.bookmarkphysics.iop.org/
Broberg, K.B. (1999) Cracks and Fracture, London, Academic. 752 p.
Burgmann, R., Pollard, D.D. and Martel, S.J. (1994) Slip distributions on faults: effects of stress gradients, inelastic
deformation, heterogeneous host-rock stiffness, and fault interaction, J. Struct. Geol. 16, pp. 1675-1690.
Clayton, L. (1966) Tectonic depressions along the Hase fault, a transcurrent fault in north Canterbury, New Zealand,
New Zealand J. Geol. Geophys. Vol. 9, pp. 94-104.
Freund, L.B. (1990) Dynamic fracture mechanics, Cambridge, Cambridge University Press.
Gay, N.C. and Ortlepp, W.D. (1979) Anatomy of a mining-induced fault zone. Geol. Soc. Of America Bull. Part 1,
Vol. 90, pp. 47-58.
Grady, D.E. and Kipp, M.E. (1980) Int. J. Rock Mech. Min. Sci., Vol. 17, p. 147.
Grady, D.E. (1982) J. Appl. Phys., Vol. 55, p. 322.
Granier, T. (1985) Origin, damping and pattern of development of faults in granite, Tectonics, Vol. 4, pp. 721-737.
Harris, R.A. and Day, S.M. (1993) Dynamics of fault interaction: parallel strike-slip faults. J. Geophys. Res., Vol. 98,
Hopkinson, B. (1910) Scientific Papers, Cambridge University Press, London.
Hopkinson, B. (1914) Trans. Roy. Soc., London, 213A, p. 437.
Kanamori, H. and Brodsky, E. (2001) The physics of earthquakes, Phys. Today, Vol. 54, pp. 34-40.
Lonnitz-Adler, J. (1991) Model for steady-state friction. J. Geophys. Rev. 96, No. B4, pp. 6121-6131.
Lurie, J. (1991) Private communication, Dr. J. Lurie of Technikon, Witwatersrand, Johannesburg. South Africa (Fax
McGarr, A. (2001) Control of strong ground motion of mining-induced earthquakes by the strength of the seismogenic
rockmass. 5th Int. Symp. on Rockbursts and Seismicity in Mines – RaSiM 5, SAIMM, Johannesburg, 2001.
Melosh, H.J. (1996) Dynamical weakening of faults by acoustic fluidization. Nature, Vol. 379.
Meyers, M.A. (1994) Dynamic behaviour of materials. John Wiley & Sons, Inc. 668 p.
Ortlepp, W.D. (1992) Note on fault-slip motion inferred from a study of micro-cataclastic particles from an
underground shear rupture. PAGEOPH, Vol. 139, No. 3/4, pp. 677-695.
Ortlepp, W.D. (1997) Rock fracture and rockbursts. SAIMM Monograph Series, MJ, Johannesburg.
Ortlepp, W.D. (1999) Observation of mining-induced faults in an intact rock mass at depth. Int. J. Rock Mech., Vol. 37,
Ortlepp, W.D. (2001) Thoughts on the rockburst source mechanism based on observations of the mine-induced shear
rupture. 5th International Symposium on Rockburst and Seismicity in Mines (RaSiM5), Johannesburg, South
Africa, pp. 43-51.
Ortlepp, W.D., Armstrong, R., Ryder, J.A. and O’Connor, D. (2005) Fundamental study of micro-fracturing on the slip
surface of mine-induced dynamic brittle shear zones. 6th International Symposium on Rockburst and Seismicity
in Mines Proceedings, Perth, Australia, March, 2005.
Poliakov, A.N.B., Domowska, R. and Rice, J.R. (2002) Dynamic shear rupture interactions with fault bends and off-
axis secondary faulting, J. Geophys. Res. 107, No. B11, 2295, doi 10.1029/2001JB000572, ESE 6-1-6-18.
Rice, J.R., Sammis, C.G. and Parsons, R. (2005) Off-fault secondary failure induced by a dynamic slip pulse. Bull.
Seismol. Soc. Am. Vol. 95, No. 1, pp. 109-134.
Rosakis, A.J., Samudrala, O. and Coker, D. (1999) Cracks faster than the shear wave speed. Science, Vol. 284,
Rosakis, A.J. (2002) Intersonic shear cracks and fault ruptures. Advances in Physics, Vol. 51, No. 4, pp. 1189-1257.
Rock Behaviour Under High Stress
Deep Mining 07, Perth, Australia 191
Rosakis, A.J, Kanamori, H. and Xia, K. (2006) Laboratory earthquakes, Int. J. Fracture, Vol. 138, pp. 211-218.
Scholz, C.H. (2002) The mechanics of earthquakes and faulting. Cambridge University Press.
Segall, P. and Pollard, D.D. (1980) The mechanics of discontinuous faults, J. Geophys. Res., Vol. 85, pp. 4337-4250.
Segall, P. and Pollard, D.D. (1983) Nucleation and growth of strike-slip faults in granite, J. Geophys. Res., Vol. 88,
Sharp, R.V. and Clark, M.M. (1972) Geologic evidence of previous faulting near the 1968 rupture on the Coyote Creek
fault, U.S. Geol. Surv. Proof. Pap., Vol. 787, pp. 131-140.
Sibson, R.H. (1985) Stopping of earthquake ruptures at dilatational jogs. Nature, Vol. 316, pp. 248-251.
Sibson, R.H. (1986) Rupture interaction with fault jogs, Earthquake source mechanisms. S. Das, J. Boatwright and C.H.
Scholz (eds), American Geophysical Union, Washington.
Tarasov, B.G. (2007) Intersonic shear rupture mechanism (submitted to Int. J. Rock Mechanics 12.02.2007).
Tarasov, B.G. and Randolph, M.F. (2007a) Frictionless shear at great depth and other paradoxes of hard rocks, Int. J.
Rock Mechanics (in press).
Tarasov, B.G. and Randolph, M.F. (2007b) Paradoxical features of primary fractures and general faults. 4th International
Seminar on Deep and High Stress Mining (Deep Mining 07), Perth, Western Australia, 7-9 November 2007.
Vermilye, J.M. and Scholz, C.H. (1999) Fault propagation and segmentation: insight from the microstructural
examination of a small fault. J. Struct. Geol., Vol. 21, pp. 1623-1636.
Shock Loading-Unloading Mechanism in Rockburst Shear Fractures in Quartzite Causing
Genesis of Polyhedral Sub-Particles in the Fault Gouge B.G. Tarasov, W.D. Ortlepp
192 Deep Mining 07, Perth, Australia