Tarasov, BG 2017, 'Shear ruptures of extreme dynamics in laboratory and natural conditions', in J Wesseloo (ed.), Deep Mining 2017: Proceedings of the Eighth International Conference on Deep and High Stress Mining
, Australian Centre for Geomechanics, Perth, pp. 3-50, https://doi.org/10.36487/ACG_rep/1704_0.1_Tarasov
In the Earth’s crust shear ruptures are responsible for macroscopic dynamic failure causing earthquakes. Shear ruptures induced by and triggered by the mining-induced stress change sometimes result in damaging rockbursts. The fundamental mechanism of the shear rupture is critically linked to the magnitude of ground motion, and hence, any resulting damage. For the effective management of seismic hazard both from natural and mining-related causes, a comprehensive understanding of the fundamental mechanism of the shear rupture is crucial. In recent years it has been observed that shear ruptures can propagate with extreme velocities exceeding the shear wave speed. Experiments show that a remarkable feature of extreme ruptures is the fact that friction reduces toward zero in the rupture head. Coseismic reduction in friction is critical in accelerating the fault slip and to the magnitude of ground shaking which affects the amount of potential earthquake and rockburst damage. Despite the critical importance, physical processes which determine the dramatic weakening of friction are still unclear and continue to be vigorously debated. The second unresolved question is about the source of energy which provides extreme rupture dynamics. This paper shows that the nature of extreme ruptures in intact rocks and in pre-existing faults with frictional and coherent interfaces is the same. It demonstrates that in all types of extreme ruptures, the fault weakening can be explained by a recently-proposed shear rupture mechanism associated with the intensive tensilecracking process in the rupture tip observed for all extreme ruptures. The tensile-cracking process creates, in certain conditions, a fan-like fault structure, the shear resistance of which is extremely low. The fan-structure represents the basis of a self-sustaining natural mechanism of stress intensification in the rupture head providing the driving power for rupture propagation with extreme velocities. The fanmechanism causes dramatic embrittlement of intact hard rocks under high stress and makes transient strength of intact hard rocks during the rupture propagation significantly less than the frictional strength. This paper introduces features of the fanmechanism operation in primary ruptures and in natural complex faults and proposes an alternative view on the nature of earthquakes and shear rupture rockbursts generated by extreme ruptures.
Keywords: super shear, extreme rupture, fan-mechanism, Ortlepp shears, rockburst, earthquake
Albaric, J, Deverchere, J, Petit, C, Perrot, J & Le Gall, B 2009, ‘Crustal rheology and depth distribution of earthquakes: Insights from the central and southern East African Rift System’, Tectonophysics, vol. 468, pp. 28–41.
Andrews, DJ & Ben-Zion, Y 1997, ‘Wrinkle-like slip pulse on a fault between different materials’, Journal of Geophysical Research, vol. 102, pp. 553–71.
Ben-David, O, Rubinstein, SM & Fineberg, J 2010, ‘Slip-stick and the evolution of frictional strength’, Nature, vol. 463, pp. 76–79.
Ben-Zion, Y 2001, ‘Dynamic ruptures in recent models of earthquake faults’, Journal of the Mechanics and Physics of Solids, vol. 49, pp. 2209–2244.
Brace, WF & Kohlstedt, D 1980 ‘Limits on lithospheric stress imposed by laboratory experiments’, Journal of Geophysical Research, vol. 85, pp. 6248-6252.
Brace, WF & Byerlee, JD 1966, ‘Stick-slip as a mechanism for earthquakes, Science, vol. 153 (3,739), pp. 990–992.
Bowden, FP & Tabor, D 2001, The friction and lubrication of solids, Oxford University Press.
Brune, JN, Brown, S & Johnson, PA 1993, ‘Rupture mechanism and interface separation in foam rugger model of earthquakes: a possible solution to the heat flow paradox and the paradox of large overthrusts’, Tectonophysics, vol. 218, pp. 59–67.
Brune, JN, Henyey, TL & Roy, RF 1969, ‘Heat flow, stress, and rate of slip along the San Andreas fault, California’, Journal of Geophysical Research, vol. 74, pp. 3821–3827.
Byerlee, JD 1978, ‘Friction of rocks’, Pure and Applied Geophysics, vol. 116, pp. 615–626.
Cochard, A & Madariaga, R 1994, ‘Dynamic faulting under rate-dependent friction’, Pure and Applied Geophysics, vol. 142, no. 3/4, pp. 419–445.
Dieterich, JH 1979, ‘Modeling of rock friction; 1. Experimental results and constitutive equations’, Journal of Geophysical Research, vol. 84, pp. 2162–2168.
Di Toro, G, Goldsby, DL & Tullis, TE 2004, ‘Friction falls towards zero in quartz rock as slip velocity approaches seismic rates’, Nature vol. 427, pp. 436–439.
Gay, N C & Ortlepp, W D 1979, ‘Anatomy of a mining-induced fault zone’, Geological Society of America Bulletin, vol. 90, pp. 47–58.
Ghaffari, HO, Thompson, BD & Young, RP 2014, ‘Complex networks and waveforms from acoustic emissions in laboratory earthquakes’, Nonlinear Processes in Geophysics, vol. 21, pp. 763–775.
Griffith, WA, Rosakis, A, Pollard, DD & Ko, CW 2009, ‘Dynamic rupture experiments elucidate tensile crack development during propagating earthquake ruptures’, Geology, vol. 37, pp. 795–798.
Heaton, TH 1990, ‘Evidence for and implications of self-healing pulses of slip in earthquake rupture’, Physics of the Earth and Planetary Interiors, vol. 64, no. 1, pp. 1–20.
Kanamori, H & Heaton, TH 2000, ‘Microscopic and macroscopic physics of earthquakes’, in JB Rundle, DL Turcotte & W Klein (eds), Geophysical Monograph Series: Geo Complexity and the Physics of Earthquakes, American Geophysical Union, Washington DC, vol. 120, pp. 147–163.
King, GCP & Sammis, CG 1992, ‘The mechanisms of finite brittle strain’, Pure and Applied Geophysics, vol. 138, pp. 611–640.
Kostrov, B 1966, ‘Self-similar problems of propagation of shear cracks’, Journal of Applied Mathematics and Mechanics, vol. 28, pp. 1077-1078.
Lachenbruch, AH 1980, ‘Frictional heating, fluid pressure, and the resistance to fault motion’, Journal of Geophysical Research, vol. 85, pp. 6097–6112.
Lei, X, Kusunose, K, Rao, MVMS, Nishizawa, O & Satoh, T 2000, ‘Quasi-static fault growth and cracking in homogeneous brittle rock under triaxial compression using acoustic emission monitoring’, Journal of Geophysical Research, vol. 105, pp. 6127–6139.
Lu, X, Lapusta, N & Rosakis, AJ 2007, ‘Pulse-like and crack-like ruptures in experiments mimicking crustal earthquakes’, Proceedings of the National Academy of Science USA, vol. 104, pp. 18931–18936.
Lu, X, Lapusta, N & Rosakis, AJ 2010, ‘Pulse-like and crack-like dynamic shear ruptures on frictional interfaces: experimental evidence, numerical modeling, and implications’, International Journal of Fracture,
, pp. 27–39.
Lykotrafitis, G, Rosakis, A J & Ravichandran, G 2006, ‘Self-healing pulse-like shear ruptures in the laboratory’, Science, vol. 313, pp. 1765–1768.
Magloughlin, JF & Spray, JG 1992, ‘Frictional melting processes and products in geological materials: introduction and discussion’, Tectonophysics, vol. 204, pp. 197–206.
Megahid, AR, Soghair, H, Hageed, MAA & Hafer AMAA 1993, ‘Strength and deformation capacity of slender RC beams’, in HP Rossmanith (ed.), Proceedings Fracture and Damage of Concrete and Rock – FDCR-2.
Melosh, HJ 1979, ‘Acoustic fluidization: a new geologic process?’, Journal of Geophysical Research, vol. 84, pp. 7513–7520.
McGarr, A, Pollard, D, Gay, NC & Ortlepp, WD 1979, ‘Observations and analysis of structures in exhumed mine-induced faults’, U.S. Geological Survey Open File Report, vol. 79 – 1239, pp. 101–120.
Ngo, D, Huang, Y, Rosakis, A, Griffith, W A & Pollard, D 2012, ‘Off-fault tensile cracks: a link between geological fault observations, lab experiments, and dynamic rupture models’, Journal of Geophysical Research, vol. 117,
Ohnaka, M & Kuwahara, Y 1990, ‘Characteristic features of local breakdown near a crack-tip in the transition zone from nucleation to unstable rupture during stick-slip shear failure’, Tectonophysics, vol. 175, pp. 197–220.
Ohnaka, M & Shen, L 1999, ‘Scaling of the shear rupture process from nucleation to dynamic propagation: implications of geometric irregularity of the rupturing surface’, Journal of Geophysical Research, vol. 104, pp. 817–844.
Olsen, KB, Madariaga, R & Archuleta, RJ 1997, ‘Three-dimensional dynamic simulation of the 1992 Landers earthquake’, Science, vol. 278, pp. 834–838.
Ortlepp, WD 1997, Rock Fracture and Rockbursts, The South African Institute of Mining and Metallurgy, Johannesburg.
Otsuki, K & Dilov, T 2005, ‘Evolution of hierarchical self-similar geometry of experimental fault zones: Implications for seismic nucleation and earthquake size’, Journal of Geophysical Research, vol. 110, B03303,
Peng, S & Johnson, AM 1972, ‘Crack growth and faulting in cylindrical specimens of Chelmsford granite’, International Journal of Rock Mechanics and Mining Sciences, vol. 9, pp. 37–86.
Reches, Z & Lockner, D A 1994, ‘Nucleation and growth of faults in brittle rocks’, Journal of Geophysical Research, vol. 99, pp. 18159–18173.
Rice, JR 1992, ‘Fault stress states, pore pressure distributions, and the weakness of the San Andreas fault’, Fault Mechanics and Transport Properties of Rocks, Academic, San Diego, California, pp. 475–503.
Rice, JR 2006, ‘Heating and weakening of faults during earthquake slip’, Journal of Geophysical Research, vol. 111, B05311,
Richards, PG 1976, ‘Dynamic motions near an earthquake fault: a three-dimensional solution’, Bulletin of Seismological Society of America, vol. 66, pp. 1–32.
Rosakis, A J 2002, ‘Intersonic shear cracks and fault ruptures’, Advances in Physics, vol. 51, pp. 1189-1257.
Rosakis, AJ, Samudrala, O & Coker, D 1999, ‘Cracks faster than the shear wave speed’, Science, vol. 284, pp. 1337–1340.
Rubinstein, S M, Cohen, G & Fineberg, J 2004, ‘Detachment fronts and the onset of dynamic friction’, Nature, vol. 430,
Rummel, F & Fairhurst, C 1970, ‘Determination of the post-failure behavior of brittle rock using a servo-controlled testing machine’, Rock Mechanics and Rock Engineering, vol. 2, no. 4, pp. 189–204.
Samudrala, O, Huang, Y & Rosakis, AJ 2002, ‘Subsonic and intersonic shear rupture of weak planes with a velocity weakening cohesive zone’, Journal of Geophysical Research, vol. 107 (B8), pp. 2,170,
Scholz, CH 1998, ‘Earthquakes and friction laws’, Nature, vol. 391, pp. 37–42.
Scholz, CH 2002, The mechanics of earthquakes and faulting, Cambridge University Press, Cambridge.
Segal, P & Pollard, DD 1980, ‘Mechanics of discontinuous faulting’, Journal of Geophysical Research, vol. 85, pp. 4337–4350.
Sibson, RH 1982, ‘Fault zone models, heat flow, and the depth distribution of earthquakes in the continental crust of the United States’, Bulletin of the Seismological Society of America, vol. 72, pp. 151–163.
Sibson, R 1992, ‘Power dissipation and stress levels during seismic faulting’, Journal of Geophysical Research, vol. 85, pp. 6239–6247.
Stavrogin, AN & Tarasov, BG 2001, Experimental Physics and Rock Mechanics, Balkema, Rotterdam.
Tarasov, BG 2010, ‘Superbrittleness of rocks at high confining pressure’, in M Van Sint Jan & Y Potvin (eds), Proceedings of the Fifth International Seminar on Deep and High Stress Mining, Australian Centre for Geomechanics, Perth, pp. 119–133.
Tarasov, BG 2014, ‘Hitherto unknown shear rupture mechanism as a source of instability in intact hard rocks at highly confined compression’, Tectonophysics, vol. 621, pp. 69–84.
Tarasov, BG 2016a, ‘Shear fractures of extreme dynamics’, Rock Mechanics and Rock Engineering, vol. 49, no. 10, pp. 3999–4021.
Tarasov, B 2016b, Fan-hinged shear, online video, 19 July, viewed 6 December 2016,
Tarasov, BG & Ortlepp, WD 2007, ‘Shock loading-unloading mechanism in rockburst shear fractures in quartzite causing genesis of polyhedral sub-particle in the fault gouge’, in Y Potvin (ed.) Proceedings of the Fourth International Seminar on Deep and High Stress Mining, Australian Centre for Geomechanics, Perth, pp. 183–192.
Tarasov, BG & Randolph, MF 2011, ‘Superbrittleness of rocks and earthquake activity’, International Journal of Rock Mechanics and Mining Science, vol. 48, pp. 888–898.
Tarasov, B & Potvin, Y 2013, ‘Universal criteria for rock brittleness estimation under triaxial compression’, International Journal of Rock Mechanics and Mining Science, vol. 59, pp. 57–69.
Wawersik, WR & Brace, WF 1971, ‘Post-failure behaviour of a granite and diabase’, Rock Mechanics, vol. 3, pp. 61–85.
Wawersik, WR & Fairhurst, C 1970, ‘A study of brittle rock fracture in laboratory compression experiments’, International Journal of Rock Mechanics and Mining Science, vol. 7, pp. 561–575.
Xia, K, Rosakis, A J & Kanamori, H 2004, ‘Laboratory earthquakes: the sub-Rayleigh-to-supershear rupture transition’, Science, vol. 303, pp. 1859–1861.
Zheng, G & Rice, JR 1998, ‘Conditions under which velocity-weakening friction allows a self-healing versus a crack-like mode of rupture’, Bulletin of the Seismological Society of America, vol. 88, pp. 1466–1483.