It has been proposed that large strike-slip faults such as the San Andreas contain water in seal-bounded compartments. Arguments based on heat flow and stress orientation suggest that in most of the compartments, the water pressure is so high that the average shear strength of the fault is less than 20 MPa. We propose a variation of this basic model in which most of the shear stress on the fault is supported by a small number of compartments where the pore pressure is relatively low. As a result, the fault gouge in these compartments is compacted and lithified and has a high undisturbed strength. When one of these locked regions fails, the system made up of the neighboring high and low pressure compartments can become unstable. Material in the high fluid pressure compartments is initially underconsolidated since the low effective confining pressure has retarded compaction. As these compartments are deformed, fluid pressure remains nearly unchanged so that they offer little resistance to shear. The low pore pressure compartments, however, are overconsolidated and dilate as they are sheared. Decompression of the pore fluid in these compartments lowers fluid pressure, increasing effective normal stress and shear strength. While this effect tends to stabilize the fault, it can be shown that this dilatancy hardening can be more than offset by displacement weakening of the fault (i.e., the drop from peak to residual strength). If the surrounding rock mass is sufficiently compliant to produce an instability, slip will propagate along the fault until the shear fracture runs into a low-stress region. Frictional heating and the accompanying increase in fluid pressure that are suggested to occur during shearing of the fault zone will act as additional destabilizers. However, significant heating occurs only after a finite amount of slip and therefore is more likely to contribute to the energetics of rupture propagation than to the initiation of the instability.
We present results of a one-dimensional dynamic Burridge-Knopoff-type model to demonstrate various aspects of the fluid-assisted fault instability described above. In the numerical model, the fault is represented by a series of blocks and springs, with fault rheology expressed by static and dynamic friction. In addition, the fault surface of each block has associated with it pore pressure, porosity and permeability. All of these variables are allowed to evolve with time, resulting in a wide range of phenomena related to fluid diffusion, dilatancy, compaction and heating. These phenomena include creep events, diffusion-controlled precursors, triggered earthquakes, foreshocks, aftershocks, and multiple earthquakes. While the simulations have limitations inherent to 1-D fault models, they demonstrate that the fluid compartment model can, in principle, provide the rich assortment of phenomena that have been associated with earthquakes.
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Andrews, D. J. (1989),Mechanics of Fault Junctions, J. Geophys. Res.94, 9389–9397.
Ben-Zion, Y., andRice, J. R. (1993),Earthquake Failure Sequences along a Celluar Fault Zone in a Three-dimensional Elastic Solid Containing Asperity and Nonasperity Regions, J. Geophys. Res.98, 14, 109–14, 131.
Ben-Zion, Y., andRice, J. R. (1995),Slip Patterns and Earthquake Populations along Different Classes of Faults in Elastic Solids, J. Geophys. Res.100, 12959–12983.
Blanpied, M. L., Lockner, D. A., andByerlee, J. D. (1992).An Earthquake Mechanism Based on Rapid Sealing of Faults, Nature358, 574–576.
Blanpied, M. L., Lockner, D. A., andByerlee, J. D. (1995),Frictional Slip of Granite at Hydrothermal Conditions, J. Geophys. Res.100, 13045–13064.
Burridge, R., andKnopoff, L. (1967),Model and Theoretical Seismicity, Bull. Seismol. Soc. Am.57, 341–371.
Byerlee, J. D. (1978),Friction of Rocks, Pure and Appl. Geophys.116, 615–626.
Byerlee, J. D. (1990),Friction, Overpressure and Fault Normal Compression, Geophys. Res. Lett.17, 2109–2112.
Byerlee, J. D. (1992),The Change in Orientation of Subsidiary Shears near Faults Containing Pore Fluid under High Pressure, Tectonophysics211, 295–303.
Byerlee, J. D. (1993),Model for Episodic Flow of High Pressure Water in Fault Zones before Earthquakes, Geology21, 303–306.
Byerlee, J. D., andSavage, J. C. (1992),Coulomb Plasticity within the Fault Zone, Geophys. Res. Lett.19, 2341–2344.
Carlson, J. M., andLanger, J. S. (1989),Mechanical Model of an Earthquake, Phys. Rev. A40, 6470–6484.
Carlson, J. M., Langer, J. S., Shaw, B., andTang, C. (1991),Intrinsic Properties of a Burridge-Knopoff Model of a Fault, Phys. Rev. A44, 884–897.
Dieterich, J. H. (1972),Time-dependent Friction as a Possible Mechanism for Aftershocks, J. Geophys. Res.77, 3771–3781.
Dieterich, J. H. (1978),Time-dependent Friction and the Mechanics of Stick Slip, Pure and Appl. Geophys.116, 790–806.
Fredrich, J. T., andEvans, B.,Strengh recovery along simulated faults by solution transfer processes. In 33rd U.S. Rock Mechanics Symposium (eds. Tillerson, J. R., and Warersik, W. R.) (Balkema, Rotterdam 1992) pp. 121–130.
Hickman, S. H. (1991),Stress in the Lithosphere and the Strength of Active Faults, Rev. Geophys., IUGG Report, 759–775.
Johnston, M. J. S., Linde, A. T., Gladwin, M. T., andBorcherdt, R. D. (1987),Fault Failure with Moderate Earthquakes, Tectonophysics144, 189–206.
Lachenbruch, A. H. (1980),Frictional Heating, Fluid Pressure, and the Resistance to Fault Motion, J. Geophys. Res.85, 6097–6112.
Lachenbruch, A. H., andSass, J. H. (1980),Heat Flow and Energetics of the San Andreas Fault Zone, J. Geophys. Res.85, 6185–6222.
Li, Y.-G., Vidale, J. E., Aki, K., Marone, C. J., andLee, W. H. K. (1994),Fine Structure of the Landers Fault Zone: Segmentation and the Rupture Process, Science265, 367–370.
Lockner, D. A.,Rock failure. InAGU Handbook of Physical Constants (ed. Ahrens, T. J.) (Am. Geophys. Union, Washington, D.C. 1995)3–10, 127–147.
Lockner, D. A., andByerlee, J. D. (1993),How Geometric Constraints Contribute to the Weakness of Mature Faults, Nature363, 250–252.
Lockner, D. A., andByerlee, J. D. (1994),Dilatancy in Hydraulically Isolated Faults and the Suppression of Instability, Geophys. Res. Lett.21, 2353–2356.
Lockner, D. A., Okubo, P. G., andDieterich, J. H. (1982),Containment of Stick-slip Failures on a Simulated Fault by Pore Fluid Injection, Geophys. Res. Lett.9, 801–804.
Marone, C., andKilgore, B. (1993),Scaling of the Critical Slip Distance for Seismic Faulting with Shear Strain in Fault Zones, Nature362, 618–621.
Marone, C., Raleigh, C. B., andScholz, C. H. (1990),Frictional Behavior and Constitutive Modelling of Simulated Fault Gouge, J. Geophys. Res.95, 7007–7025.
Moore, D. E., Lockner, D. A., andByerlee, J. D. (1994),Reduction of Permeability in Granite at Elevated Temperatures, Science265, 1558–1561.
Moore, D. E., Summer, R., andByerlee, J. D. (1986),The Effects of Sliding Velocity on the Frictional and Physical Properties of Heated Fault Gouge, Pure and Appl. Geophys.124, 31–52.
Morrow, C., Lockner, D., andByerlee, J.,Velocity-and time-dependent transients in simulated fault gouge, InProc. of Int. Symp. on Engineering in Complex Rock Formations (Int. Soc. Rock Mech., Beijing 1986).
Morrow, C., Radney, B., andByerlee, J.,Frictional strength and the effective pressure law of montmorillonite and illite clays. InFault Mechanics and Transport Properties of Rocks (eds. Evans, B., and Wong, T.-f.) (Academic Press, London 1992) pp. 69–88.
Morrow, C. A., andByerlee, J. D. (1989),Experimental Studies of Compaction and Dilatancy during Frictional Sliding on Faults Containing Gouge, J. Struct. Geol.11, 815–825.
Nur, A., andBooker, J. R. (1972),Aftershocks Caused by Pore Fluid Flow? Science175, 885–887.
Reinen, L. A., Weeks, J. D., andTullis, T. E. (1994),The Frictional Behavior of Lizardite and Antigorite Serpentinites: Experiments, Constitutive Models, and Implications for Natural Foult, Pure and Appl. Geophys.143, 317–358.
Rice, J. R.,Fault stress states, pore pressure distributions, and the weakness of the San Andreas faults. InFault Mechanics and Transport Properties of Rocks (eds. Evans, B., and Wong, T.-f.) (Academic Press, London 1992), pp. 475–503.
Rice, J. R. (1993),Spatio-temporal Complexity of Slip on a Fault, J. Geophys. Res.98, 9885–9907.
Robertson, E. C. (1983),Relationship of Fault Displacement to Gouge and Breccia Thickness, Trans. A.I.M.E.35, 1426–1432.
Rudnicki, J. W., andChen, C.-H. (1988),Stabilization of Rapid Frictional Slip on a Weakening Fault by Dilatant Hardening, J. Geophys. Res.93, 4745–4757.
Scholz, C. H., Sykes, L. R., andAggarwal, Y. P. (1973),Earthquake Prediction: A Physical Basis, Science181, 803–810.
Sibson, R. H. (1982),Fault Zone Models, Heat Flow, and the Depth Distribution of Earthquakes in the Continental Crust of the United States, Bull. Seismol. Soc. Am.72, 151–163.
Sleep, N. H., andBlanpied, M. L. (1992),Creep, Compaction and the Weak Rheology of Major Faults, Nature359, 687–692.
Sleep, N. H., andBlanpied, M. L. (1994),Ductile Creep and Compaction: A Mechanism for Transiently Increasing Fluid Pressure in Mostly Sealed Fault Zones, Pure and Appl. Geophys.143, 9–40.
Walther, J. V. Fluid dynamics during progressive regional metamorphism. InThe Role of Fluids In Crustal Processes (ed. Council, N. R.) (National Academy Press, Washington, D.C. 1990) pp. 64–71.
Wesson, R. L. (1988),Dynamics of Fault Creep, J. Geophys. Res.93, 8929–8951.
Zoback, M. D. et al. (1987),New Evidence on the State of Stress of the San Andreas Fault System, Science238, 1105–1111.
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Lockner, D.A., Byerlee, J.D. An earthquake instability model based on faults containing high fluid-pressure compartments. PAGEOPH 145, 717–745 (1995). https://doi.org/10.1007/BF00879597
- Earthquake cycle
- fluid compartments
- dynamic earthquake model