David A Lockner
David Lockner is a geophysicist in the Earthquake Science Center.
Science and Products
Filter Total Items: 13
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Filter Total Items: 112
Permeability reduction in granite under hydrothermal conditions
The formation of impermeable fault seals between earthquake events is a feature of many models of earthquake generation, suggesting that earthquake recurrence may depend in part on the rate of permeability reduction of fault zone materials under hydrothermal conditions. In this study, permeability measurements were conducted on intact, fractured, and gouge-bearing Westerly granite at an effective
Authors
C.A. Morrow, Diane E. Moore, D.A. Lockner
Hydrothermal minerals and microstructures in the Silangkitang geothermal field along the Great Sumatran fault zone, Sumatra, Indonesia
Detailed study of core samples of silicic tuff recovered from three geothermal wells along the strike-slip Great Sumatran fault zone near Silangkitang, North Sumatra, supports a model for enhanced hydrothermal circulation adjacent to this major plate-boundary fault. Two wells (A and C) were drilled nearly vertically ∼1 km southwest of the eastern (i.e., the principal) fault trace, and the third, d
Authors
Diane E. Moore, S. Hickman, D.A. Lockner, P.F. Dobson
Hayward Fault rocks: porosity, density, and strength measurements
Porosity, density and strength measurements were conducted on rock samples collected from the Hayward Fault region in Northern California as part of the Hayward Fault Working Group’s efforts to create a working model of the Hayward Fault. The rocks included in this study were both fine and coarse grained gabbros, altered keratophyre, basalt, sandstone, and serpentinite from various rock formations
Authors
C.A. Morrow, D.A. Lockner
The effect of mineral bond strength and adsorbed water on fault gouge frictional strength
Recent studies suggest that the tendency of many fault gouge minerals to take on adsorbed or interlayer water may strongly influence their frictional strength. To test this hypothesis, triaxial sliding experiments were conducted on 15 different single-mineral gouges with various water-adsorbing affinities. Vacuum dried samples were sheared at 100 MPa, then saturated with water and sheared farther
Authors
C.A. Morrow, Diane E. Moore, D.A. Lockner
Pore fluid pressure, apparent friction, and Coulomb failure
Many recent studies of stress-triggered seismicity rely on a fault failure model with a single free parameter, the apparent coefficient of friction, presumed to be a material constant with possible values 0 ≤ μ′ ≤ 1. These studies may present a misleading view of fault strength and the role of pore fluid pressure in earthquake failure. The parameter μ′ is intended to incorporate the effects of bot
Authors
N.M. Beeler, R. W. Simpson, S.H. Hickman, D.A. Lockner
Proceedings of the International workshop on the Nojima Fault core and borehole data analysis
No abstract available.
Authors
Koichiro Fujimoto, Hidemi Tanaka, D.A. Lockner
Premonitory slip and tidal triggering of earthquakes
We have conducted a series of laboratory simulations of earthquakes using granite cylinders containing precut bare fault surfaces at 50 MPa confining pressure. Axial shortening rates between 10−4and 10−6 mm/s were imposed to simulate tectonic loading. Average loading rate was then modulated by the addition of a small-amplitude sine wave to simulate periodic loading due to Earth tides or other sour
Authors
D.A. Lockner, N.M. Beeler
Quantitative measure of the variation in fault rheology due to fluid-rock interactions
We analyze friction data from two published suites of laboratory tests on granite in order to explore and quantify the effects of temperature (T) and pore water pressure (Pp) on the sliding behavior of faults. Rate-stepping sliding tests were performed on laboratory faults in granite containing “gouge” (granite powder), both dry at 23° to 845°C [Lockner et al., 1986], and wet (Pp = 100 MPa) at 23°
Authors
M.L. Blanpied, C.J. Marone, D.A. Lockner, J.D. Byerlee, D.P. King
A generalized law for brittle deformation of Westerly granite
A semiempirical constitutive law is presented for the brittle deformation of intact Westerly granite. The law can be extended to larger displacements, dominated by localized deformation, by including a displacement-weakening break-down region terminating in a frictional sliding regime often described by a rate- and state-dependent constitutive law. The intact deformation law, based on an Arrhenius
Authors
D.A. Lockner
Physical modeling of the formation and evolution of seismically active fault zones
Acoustic emission (AE) in rocks is studied as a model of natural seismicity. A special technique for rock loading has been used to help study the processes that control the development of AE during brittle deformation. This technique allows us to extend to hours fault growth which would normally occur very rapidly. In this way, the period of most intense interaction of acoustic events can be studi
Authors
A.V. Ponomarev, A.D. Zavyalov, V.B. Smirnov, D.A. Lockner
Permeability and porosity of the Illinois UPH 3 drillhole granite and a comparison with other deep drillhole rocks
Permeability, porosity, and volumetric strain measurements were conducted on granite cores obtained at depths of 0.7 to 1.6 km from the Illinois UPH 3 drillhole at effective confining pressures from 5 to 100 MPa. Initial permeabilities were in the range of 10-17 to 10-19 m2 and dropped rapidly with applied pressure to values between 10-20 and 10-24 m2 at 100 MPa, typical of other deep granite core
Authors
C.A. Morrow, D.A. Lockner
Strengths of serpentinite gouges at elevated temperatures
Serpentinite has been proposed as a cause of both low strength and aseismic creep of fault zones. To test these hypotheses, we have measured the strength of chrysotile-, lizardite-, and antigorite-rich serpentinite gouges under hydrothermal conditions, with emphasis on chrysotile, which has thus far received little attention. At 25°C, the coefficient of friction, μ, of chrysotile gouge is roughly
Authors
Diane E. Moore, D.A. Lockner, S. Ma, R. Summers, J.D. Byerlee
Science and Products
Filter Total Items: 13
No Result Found
Filter Total Items: 112
Permeability reduction in granite under hydrothermal conditions
The formation of impermeable fault seals between earthquake events is a feature of many models of earthquake generation, suggesting that earthquake recurrence may depend in part on the rate of permeability reduction of fault zone materials under hydrothermal conditions. In this study, permeability measurements were conducted on intact, fractured, and gouge-bearing Westerly granite at an effective
Authors
C.A. Morrow, Diane E. Moore, D.A. Lockner
Hydrothermal minerals and microstructures in the Silangkitang geothermal field along the Great Sumatran fault zone, Sumatra, Indonesia
Detailed study of core samples of silicic tuff recovered from three geothermal wells along the strike-slip Great Sumatran fault zone near Silangkitang, North Sumatra, supports a model for enhanced hydrothermal circulation adjacent to this major plate-boundary fault. Two wells (A and C) were drilled nearly vertically ∼1 km southwest of the eastern (i.e., the principal) fault trace, and the third, d
Authors
Diane E. Moore, S. Hickman, D.A. Lockner, P.F. Dobson
Hayward Fault rocks: porosity, density, and strength measurements
Porosity, density and strength measurements were conducted on rock samples collected from the Hayward Fault region in Northern California as part of the Hayward Fault Working Group’s efforts to create a working model of the Hayward Fault. The rocks included in this study were both fine and coarse grained gabbros, altered keratophyre, basalt, sandstone, and serpentinite from various rock formations
Authors
C.A. Morrow, D.A. Lockner
The effect of mineral bond strength and adsorbed water on fault gouge frictional strength
Recent studies suggest that the tendency of many fault gouge minerals to take on adsorbed or interlayer water may strongly influence their frictional strength. To test this hypothesis, triaxial sliding experiments were conducted on 15 different single-mineral gouges with various water-adsorbing affinities. Vacuum dried samples were sheared at 100 MPa, then saturated with water and sheared farther
Authors
C.A. Morrow, Diane E. Moore, D.A. Lockner
Pore fluid pressure, apparent friction, and Coulomb failure
Many recent studies of stress-triggered seismicity rely on a fault failure model with a single free parameter, the apparent coefficient of friction, presumed to be a material constant with possible values 0 ≤ μ′ ≤ 1. These studies may present a misleading view of fault strength and the role of pore fluid pressure in earthquake failure. The parameter μ′ is intended to incorporate the effects of bot
Authors
N.M. Beeler, R. W. Simpson, S.H. Hickman, D.A. Lockner
Proceedings of the International workshop on the Nojima Fault core and borehole data analysis
No abstract available.
Authors
Koichiro Fujimoto, Hidemi Tanaka, D.A. Lockner
Premonitory slip and tidal triggering of earthquakes
We have conducted a series of laboratory simulations of earthquakes using granite cylinders containing precut bare fault surfaces at 50 MPa confining pressure. Axial shortening rates between 10−4and 10−6 mm/s were imposed to simulate tectonic loading. Average loading rate was then modulated by the addition of a small-amplitude sine wave to simulate periodic loading due to Earth tides or other sour
Authors
D.A. Lockner, N.M. Beeler
Quantitative measure of the variation in fault rheology due to fluid-rock interactions
We analyze friction data from two published suites of laboratory tests on granite in order to explore and quantify the effects of temperature (T) and pore water pressure (Pp) on the sliding behavior of faults. Rate-stepping sliding tests were performed on laboratory faults in granite containing “gouge” (granite powder), both dry at 23° to 845°C [Lockner et al., 1986], and wet (Pp = 100 MPa) at 23°
Authors
M.L. Blanpied, C.J. Marone, D.A. Lockner, J.D. Byerlee, D.P. King
A generalized law for brittle deformation of Westerly granite
A semiempirical constitutive law is presented for the brittle deformation of intact Westerly granite. The law can be extended to larger displacements, dominated by localized deformation, by including a displacement-weakening break-down region terminating in a frictional sliding regime often described by a rate- and state-dependent constitutive law. The intact deformation law, based on an Arrhenius
Authors
D.A. Lockner
Physical modeling of the formation and evolution of seismically active fault zones
Acoustic emission (AE) in rocks is studied as a model of natural seismicity. A special technique for rock loading has been used to help study the processes that control the development of AE during brittle deformation. This technique allows us to extend to hours fault growth which would normally occur very rapidly. In this way, the period of most intense interaction of acoustic events can be studi
Authors
A.V. Ponomarev, A.D. Zavyalov, V.B. Smirnov, D.A. Lockner
Permeability and porosity of the Illinois UPH 3 drillhole granite and a comparison with other deep drillhole rocks
Permeability, porosity, and volumetric strain measurements were conducted on granite cores obtained at depths of 0.7 to 1.6 km from the Illinois UPH 3 drillhole at effective confining pressures from 5 to 100 MPa. Initial permeabilities were in the range of 10-17 to 10-19 m2 and dropped rapidly with applied pressure to values between 10-20 and 10-24 m2 at 100 MPa, typical of other deep granite core
Authors
C.A. Morrow, D.A. Lockner
Strengths of serpentinite gouges at elevated temperatures
Serpentinite has been proposed as a cause of both low strength and aseismic creep of fault zones. To test these hypotheses, we have measured the strength of chrysotile-, lizardite-, and antigorite-rich serpentinite gouges under hydrothermal conditions, with emphasis on chrysotile, which has thus far received little attention. At 25°C, the coefficient of friction, μ, of chrysotile gouge is roughly
Authors
Diane E. Moore, D.A. Lockner, S. Ma, R. Summers, J.D. Byerlee