David A Lockner
David Lockner is a geophysicist in the Earthquake Science Center.
Science and Products
Filter Total Items: 13
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Effect of clay content and mineralogy on frictional sliding behavior of simulated gouges: binary and ternary mixtures of quartz, illite, and montmorillonite
We investigated the frictional sliding behavior of simulated quartz-clay gouges under stress conditions relevant to seismogenic depths. Conventional triaxial compression tests were conducted at 40 MPa effective normal stress on saturated saw cut samples containing binary and ternary mixtures of quartz, montmorillonite, and illite. In all cases, frictional strengths of mixtures fall between the end
Authors
Sheryl Tembe, David A. Lockner, Teng-Fong Wong
Anomalously low strength of serpentinite sheared against granite and implications for creep on the Hayward and Calaveras Faults
Serpentinized ophiolitic rocks are juxtaposed against quartzofeldspathic rocks at depth across considerable portions of the Hayward and Calaveras Faults. The marked compositional contrast between these rock types may contribute to fault creep that has been observed along these faults. To investigate this possibility, we are conducting hydrothermal shearing experiments to look for changes in fricti
Authors
Diane E. Moore, David A. Lockner, David A. Ponce
Fault-related clay authigenesis along the Moab Fault: Implications for calculations of fault rock composition and mechanical and hydrologic fault zone properties
The presence of clays in fault rocks influences both the mechanical and hydrologic properties of clay-bearing faults, and therefore it is critical to understand the origin of clays in fault rocks and their distributions is of great importance for defining fundamental properties of faults in the shallow crust. Field mapping shows that layers of clay gouge and shale smear are common along the Moab F
Authors
J.G. Solum, N.C. Davatzes, D.A. Lockner
Fault weakening and earthquake instability by powder lubrication
Earthquake instability has long been attributed to fault weakening during accelerated slip1, and a central question of earthquake physics is identifying the mechanisms that control this weakening2. Even with much experimental effort2-12, the weakening mechanisms have remained enigmatic. Here we present evidence for dynamic weakening of experimental faults that are sheared at velocities approaching
Authors
Z. Reches, D.A. Lockner
Constraints on the stress state of the San Andreas fault with analysis based on core and cuttings from SAFOD drilling phases 1 and 2
Analysis of field data has led different investigators to conclude that the San Andreas Fault (SAF) has either anomalously low frictional sliding strength (μ < 0.2) or strength consistent with standard laboratory tests (μ > 0.6). Arguments for the apparent weakness of the SAF generally hinge on conceptual models involving intrinsically weak gouge or elevated pore pressure within the fault zone. So
Authors
Cheryl Tembe, David A. Lockner, Teng-fong Wong
Geometry of the Nojima fault at Nojima-Hirabayashi, Japan - II. Microstructures and their implications for permeability and strength
Samples of damage-zone granodiorite and fault core from two drillholes into the active, strike-slip Nojima fault zone display microstructures and alteration features that explain their measured present-day strengths and permeabilities and provide insight on the evolution of these properties in the fault zone. The least deformed damage-zone rocks contain two sets of nearly perpendicular (60–90° ang
Authors
Diane E. Moore, D.A. Lockner, H. Ito, R. Ikeda, H. Tanaka, K. Omura
Geometry of the Nojima fault at Nojima-Hirabayashi, Japan - I. A simple damage structure inferred from borehole core permeability
The 1995 Kobe (Hyogo-ken Nanbu) earthquake, M = 7.2, ruptured the Nojima fault in southwest Japan. We have studied core samples taken from two scientific drillholes that crossed the fault zone SW of the epicentral region on Awaji Island. The shallower hole, drilled by the Geological Survey of Japan (GSJ), was started 75 m to the SE of the surface trace of the Nojima fault and crossed the fault at
Authors
David A. Lockner, Hidemi Tanaka, Hisao Ito, Ryuji Ikeda, Kentaro Omura, Hisanobu Naka
Premonitory acoustic emissions and stick-slip in natural and smooth-faulted Westerly granite
A stick-slip event was induced in a cylindrical sample of Westerly granite containing a preexisting natural fault by loading at constant confining pressure of 150 MPa. Continuously recorded acoustic emission (AE) data and computer tomography (CT)-generated images of the fault plane were combined to provide a detailed examination of microscale processes operating on the fault. The dynamic stick-sli
Authors
B.D. Thompson, R.P. Young, David A. Lockner
Talc friction in the temperature range 25°–400 °C: relevance for fault-zone weakening
Talc is one of the weakest minerals that is associated with fault zones. Triaxial friction experiments conducted on water-saturated talc gouge at room temperature yield values of the coefficient of friction, μ(shear stress, τ/effective normal stress, σ′N) in the range 0.16–0.23, and μ increases with increasing σ′N. Talc gouge heated to temperatures of 100°–400 °C is consistently weaker than at roo
Authors
Diane E. Moore, David A. Lockner
Comparative deformation behavior of minerals in serpentinized ultramafic rock: Application to the slab-mantle interface in subduction zones
The layer-structure minerals serpentine, brucite, and talc are postulated to form in the mantle wedge above a subducting slab as a result of progressive hydration and silica metasomatism. Tectonic mixing at the slab-mantle interface generates serpentinite mélanges that contain blocks of high-pressure (HP) or ultrahigh-pressure (UHP) metamorphic rock derived from the subducting slab. Such serpentin
Authors
Diane E. Moore, David A. Lockner
San Andreas Fault Zone mineralogy, geochemistry, and physical properties from SAFOD cuttings and core
No abstract available.
Authors
J. G. Solum, S. Hickman, D.A. Lockner, S. Tembe, J.P. Evans, S. D. Draper, D. C. Barton, D. L. Kirschner, J. Chester, F. M. Chester, B.A. van der Pluijm, A. M. Schleicher, Diane E. Moore, Carolyn A. Morrow, K. R. Bradbury, W. M. Calvin, T.-F. Wong
Physical properties of two core samples from Well 34-9RD2 at the Coso geothermal field, California
The Coso geothermal field, located along the Eastern California Shear Zone, is composed of fractured granitic rocks above a shallow heat source. Temperatures exceed 640 ?F (~338 ?C) at a depth of less than 10000 feet (3 km). Permeability varies throughout the geothermal field due to the competing processes of alteration and mineral precipitation, acting to reduce the interconnectivity of faults an
Authors
C.A. Morrow, D.A. Lockner
Science and Products
Filter Total Items: 13
No Result Found
Filter Total Items: 112
Effect of clay content and mineralogy on frictional sliding behavior of simulated gouges: binary and ternary mixtures of quartz, illite, and montmorillonite
We investigated the frictional sliding behavior of simulated quartz-clay gouges under stress conditions relevant to seismogenic depths. Conventional triaxial compression tests were conducted at 40 MPa effective normal stress on saturated saw cut samples containing binary and ternary mixtures of quartz, montmorillonite, and illite. In all cases, frictional strengths of mixtures fall between the end
Authors
Sheryl Tembe, David A. Lockner, Teng-Fong Wong
Anomalously low strength of serpentinite sheared against granite and implications for creep on the Hayward and Calaveras Faults
Serpentinized ophiolitic rocks are juxtaposed against quartzofeldspathic rocks at depth across considerable portions of the Hayward and Calaveras Faults. The marked compositional contrast between these rock types may contribute to fault creep that has been observed along these faults. To investigate this possibility, we are conducting hydrothermal shearing experiments to look for changes in fricti
Authors
Diane E. Moore, David A. Lockner, David A. Ponce
Fault-related clay authigenesis along the Moab Fault: Implications for calculations of fault rock composition and mechanical and hydrologic fault zone properties
The presence of clays in fault rocks influences both the mechanical and hydrologic properties of clay-bearing faults, and therefore it is critical to understand the origin of clays in fault rocks and their distributions is of great importance for defining fundamental properties of faults in the shallow crust. Field mapping shows that layers of clay gouge and shale smear are common along the Moab F
Authors
J.G. Solum, N.C. Davatzes, D.A. Lockner
Fault weakening and earthquake instability by powder lubrication
Earthquake instability has long been attributed to fault weakening during accelerated slip1, and a central question of earthquake physics is identifying the mechanisms that control this weakening2. Even with much experimental effort2-12, the weakening mechanisms have remained enigmatic. Here we present evidence for dynamic weakening of experimental faults that are sheared at velocities approaching
Authors
Z. Reches, D.A. Lockner
Constraints on the stress state of the San Andreas fault with analysis based on core and cuttings from SAFOD drilling phases 1 and 2
Analysis of field data has led different investigators to conclude that the San Andreas Fault (SAF) has either anomalously low frictional sliding strength (μ < 0.2) or strength consistent with standard laboratory tests (μ > 0.6). Arguments for the apparent weakness of the SAF generally hinge on conceptual models involving intrinsically weak gouge or elevated pore pressure within the fault zone. So
Authors
Cheryl Tembe, David A. Lockner, Teng-fong Wong
Geometry of the Nojima fault at Nojima-Hirabayashi, Japan - II. Microstructures and their implications for permeability and strength
Samples of damage-zone granodiorite and fault core from two drillholes into the active, strike-slip Nojima fault zone display microstructures and alteration features that explain their measured present-day strengths and permeabilities and provide insight on the evolution of these properties in the fault zone. The least deformed damage-zone rocks contain two sets of nearly perpendicular (60–90° ang
Authors
Diane E. Moore, D.A. Lockner, H. Ito, R. Ikeda, H. Tanaka, K. Omura
Geometry of the Nojima fault at Nojima-Hirabayashi, Japan - I. A simple damage structure inferred from borehole core permeability
The 1995 Kobe (Hyogo-ken Nanbu) earthquake, M = 7.2, ruptured the Nojima fault in southwest Japan. We have studied core samples taken from two scientific drillholes that crossed the fault zone SW of the epicentral region on Awaji Island. The shallower hole, drilled by the Geological Survey of Japan (GSJ), was started 75 m to the SE of the surface trace of the Nojima fault and crossed the fault at
Authors
David A. Lockner, Hidemi Tanaka, Hisao Ito, Ryuji Ikeda, Kentaro Omura, Hisanobu Naka
Premonitory acoustic emissions and stick-slip in natural and smooth-faulted Westerly granite
A stick-slip event was induced in a cylindrical sample of Westerly granite containing a preexisting natural fault by loading at constant confining pressure of 150 MPa. Continuously recorded acoustic emission (AE) data and computer tomography (CT)-generated images of the fault plane were combined to provide a detailed examination of microscale processes operating on the fault. The dynamic stick-sli
Authors
B.D. Thompson, R.P. Young, David A. Lockner
Talc friction in the temperature range 25°–400 °C: relevance for fault-zone weakening
Talc is one of the weakest minerals that is associated with fault zones. Triaxial friction experiments conducted on water-saturated talc gouge at room temperature yield values of the coefficient of friction, μ(shear stress, τ/effective normal stress, σ′N) in the range 0.16–0.23, and μ increases with increasing σ′N. Talc gouge heated to temperatures of 100°–400 °C is consistently weaker than at roo
Authors
Diane E. Moore, David A. Lockner
Comparative deformation behavior of minerals in serpentinized ultramafic rock: Application to the slab-mantle interface in subduction zones
The layer-structure minerals serpentine, brucite, and talc are postulated to form in the mantle wedge above a subducting slab as a result of progressive hydration and silica metasomatism. Tectonic mixing at the slab-mantle interface generates serpentinite mélanges that contain blocks of high-pressure (HP) or ultrahigh-pressure (UHP) metamorphic rock derived from the subducting slab. Such serpentin
Authors
Diane E. Moore, David A. Lockner
San Andreas Fault Zone mineralogy, geochemistry, and physical properties from SAFOD cuttings and core
No abstract available.
Authors
J. G. Solum, S. Hickman, D.A. Lockner, S. Tembe, J.P. Evans, S. D. Draper, D. C. Barton, D. L. Kirschner, J. Chester, F. M. Chester, B.A. van der Pluijm, A. M. Schleicher, Diane E. Moore, Carolyn A. Morrow, K. R. Bradbury, W. M. Calvin, T.-F. Wong
Physical properties of two core samples from Well 34-9RD2 at the Coso geothermal field, California
The Coso geothermal field, located along the Eastern California Shear Zone, is composed of fractured granitic rocks above a shallow heat source. Temperatures exceed 640 ?F (~338 ?C) at a depth of less than 10000 feet (3 km). Permeability varies throughout the geothermal field due to the competing processes of alteration and mineral precipitation, acting to reduce the interconnectivity of faults an
Authors
C.A. Morrow, D.A. Lockner