David A Lockner
David Lockner is a geophysicist in the Earthquake Science Center.
Science and Products
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Evolution of wear and friction along experimental faults
We investigate the evolution of wear and friction along experimental faults composed of solid rock blocks. This evolution is analyzed through shear experiments along five rock types, and the experiments were conducted in a rotary apparatus at slip velocities of 0.002–0.97 m/s, slip distances from a few millimeters to tens of meters, and normal stress of 0.25–6.9 MPa. The wear and friction measurem
Authors
Yeval Boneh, Jefferson C. Chang, David A. Lockner, Zeev Reches
Frictional properties of exhumed fault gouges in DFDP-1 cores, Alpine Fault, New Zealand
Principal slip zone gouges recovered during the Deep Fault Drilling Project (DFDP-1), Alpine Fault, New Zealand, were deformed in triaxial friction experiments at temperatures, T, of up to 350°C, effective normal stresses, σn′, of up to 156 MPa, and velocities between 0.01 and 3 µm/s. Chlorite/white mica-bearing DFDP-1A blue gouge, 90.62 m sample depth, is frictionally strong (friction coefficient
Authors
Carolyn Boulton, Diane E. Moore, David A. Lockner, Virginia G. Toy, John Townend, Rupert Southerland
Chemical controls on fault behavior: weakening of serpentinite sheared against quartz-bearing rocks and its significance for fault creep in the San Andreas system
The serpentinized ultramafic rocks found in many plate-tectonic settings commonly are juxtaposed against crustal rocks along faults, and the chemical contrast between the rock types potentially could influence the mechanical behavior of such faults. To investigate this possibility, we conducted triaxial experiments under hydrothermal conditions (200-350°C), shearing serpentinite gouge between for
Authors
Diane E. Moore, David A. Lockner
Rapid acceleration leads to rapid weakening in earthquake-like laboratory experiments
After nucleation, a large earthquake propagates as an expanding rupture front along a fault. This front activates countless fault patches that slip by consuming energy stored in Earth’s crust. We simulated the slip of a fault patch by rapidly loading an experimental fault with energy stored in a spinning flywheel. The spontaneous evolution of strength, acceleration, and velocity indicates that our
Authors
Jefferson C. Chang, David A. Lockner, Z. Reches
Effects of smectite to illite transformation on the frictional strength and sliding stability of intact marine mudstones
At subduction zones, earthquake nucleation and coseismic slip occur only within a limited depth range, known as the “seismogenic zone”. One leading hypothesis for the upper aseismic-seismic transition is that transformation of smectite to illite at ∼100–150°C triggers a change from rate-strengthening frictional behavior that allows only stable sliding, to rate weakening behavior considered a prere
Authors
Demian M. Saffer, David A. Lockner, Alex McKiernan
Laboratory triggering of stick-slip events by oscillatory loading in the presence of pore fluid with implications for physics of tectonic tremor
The physical mechanism by which the low-frequency earthquakes (LFEs) that make up portions of tectonic (also called non-volcanic) tremor are created is poorly understood. In many areas of the world, tectonic tremor and LFEs appear to be strongly tidally modulated, whereas ordinary earthquakes are not. Anomalous seismic wave speeds, interpreted as high pore fluid pressure, have been observed in reg
Authors
Noel M. Bartlow, David A. Lockner, Nicholas M. Beeler
The role of adsorbed water on the friction of a layer of submicron particles
Anomalously low values of friction observed in layers of submicron particles deformed in simple shear at high slip velocities are explained as the consequence of a one nanometer thick layer of water adsorbed on the particles. The observed transition from normal friction with an apparent coefficient near μ = 0.6 at low slip speeds to a coefficient near μ = 0.3 at higher slip speeds is attributed to
Authors
Charles G. Sammis, David A. Lockner, Ze’ev Reches
Frictional strengths of talc-serpentine and talc-quartz mixtures
Talc is a constituent of faults in a variety of settings, and it may be an effective weakening agent depending on its abundance and distribution within a fault. We conducted frictional strength experiments under hydrothermal conditions to determine the effect of talc on the strengths of synthetic gouges of lizardite and antigorite serpentinites and of quartz. Small amounts of talc weaken serpentin
Authors
Diane E. Moore, D.A. Lockner
Low strength of deep San Andreas fault gouge from SAFOD core
The San Andreas fault accommodates 28–34 mm yr−1 of right lateral motion of the Pacific crustal plate northwestward past the North American plate. In California, the fault is composed of two distinct locked segments that have produced great earthquakes in historical times, separated by a 150-km-long creeping zone. The San Andreas Fault Observatory at Depth (SAFOD) is a scientific borehole located
Authors
David A. Lockner, Carolyn A. Morrow, Diane E. Moore, Stephen H. Hickman
Earthquake rupture at focal depth, part II: mechanics of the 2004 M2.2 earthquake along the Pretorius Fault, TauTona Mine, South Africa
We analyze here the rupture mechanics of the 2004, M2.2 earthquake based on our observations and measurements at focal depth (Part I). This event ruptured the Archean Pretorius fault that has been inactive for at least 2 Ga, and was reactivated due to mining operations down to a depth of 3.6 km depth. Thus, it was expected that the Pretorius fault zone will fail similarly to an intact rock body in
Authors
V. Heesakkers, S. Murphy, D.A. Lockner, Z. Reches
Dependence of frictional strength on compositional variations of Hayward fault rock gouges
The northern termination of the locked portion of the Hayward Fault near Berkeley, California, is found to coincide with the transition from strong Franciscan metagraywacke to melange on the western side of the fault. Both of these units are juxtaposed with various serpentinite, gabbro and graywacke units to the east, suggesting that the gouges formed within the Hayward Fault zone may vary widely
Authors
Carolyn A. Morrow, Diane E. Moore, David A. Lockner
Oscillating load-induced acoustic emission in laboratory experiment
Spatial and temporal patterns of acoustic emission (AE) were studied. A pre-fractured cylinder of granite was loaded in a triaxial machine at 160 MPa confining pressure until stick-slip events occurred. The experiments were conducted at a constant strain rate of 10−7 s−1 that was modulated by small-amplitude sinusoidal oscillations with periods of 175 and 570 seconds. Amplitude of the oscillations
Authors
Alexander Ponomarev, David A. Lockner, S. Stroganova, S. Stanchits, V. Smirnov
Science and Products
Filter Total Items: 13
No Result Found
Filter Total Items: 112
Evolution of wear and friction along experimental faults
We investigate the evolution of wear and friction along experimental faults composed of solid rock blocks. This evolution is analyzed through shear experiments along five rock types, and the experiments were conducted in a rotary apparatus at slip velocities of 0.002–0.97 m/s, slip distances from a few millimeters to tens of meters, and normal stress of 0.25–6.9 MPa. The wear and friction measurem
Authors
Yeval Boneh, Jefferson C. Chang, David A. Lockner, Zeev Reches
Frictional properties of exhumed fault gouges in DFDP-1 cores, Alpine Fault, New Zealand
Principal slip zone gouges recovered during the Deep Fault Drilling Project (DFDP-1), Alpine Fault, New Zealand, were deformed in triaxial friction experiments at temperatures, T, of up to 350°C, effective normal stresses, σn′, of up to 156 MPa, and velocities between 0.01 and 3 µm/s. Chlorite/white mica-bearing DFDP-1A blue gouge, 90.62 m sample depth, is frictionally strong (friction coefficient
Authors
Carolyn Boulton, Diane E. Moore, David A. Lockner, Virginia G. Toy, John Townend, Rupert Southerland
Chemical controls on fault behavior: weakening of serpentinite sheared against quartz-bearing rocks and its significance for fault creep in the San Andreas system
The serpentinized ultramafic rocks found in many plate-tectonic settings commonly are juxtaposed against crustal rocks along faults, and the chemical contrast between the rock types potentially could influence the mechanical behavior of such faults. To investigate this possibility, we conducted triaxial experiments under hydrothermal conditions (200-350°C), shearing serpentinite gouge between for
Authors
Diane E. Moore, David A. Lockner
Rapid acceleration leads to rapid weakening in earthquake-like laboratory experiments
After nucleation, a large earthquake propagates as an expanding rupture front along a fault. This front activates countless fault patches that slip by consuming energy stored in Earth’s crust. We simulated the slip of a fault patch by rapidly loading an experimental fault with energy stored in a spinning flywheel. The spontaneous evolution of strength, acceleration, and velocity indicates that our
Authors
Jefferson C. Chang, David A. Lockner, Z. Reches
Effects of smectite to illite transformation on the frictional strength and sliding stability of intact marine mudstones
At subduction zones, earthquake nucleation and coseismic slip occur only within a limited depth range, known as the “seismogenic zone”. One leading hypothesis for the upper aseismic-seismic transition is that transformation of smectite to illite at ∼100–150°C triggers a change from rate-strengthening frictional behavior that allows only stable sliding, to rate weakening behavior considered a prere
Authors
Demian M. Saffer, David A. Lockner, Alex McKiernan
Laboratory triggering of stick-slip events by oscillatory loading in the presence of pore fluid with implications for physics of tectonic tremor
The physical mechanism by which the low-frequency earthquakes (LFEs) that make up portions of tectonic (also called non-volcanic) tremor are created is poorly understood. In many areas of the world, tectonic tremor and LFEs appear to be strongly tidally modulated, whereas ordinary earthquakes are not. Anomalous seismic wave speeds, interpreted as high pore fluid pressure, have been observed in reg
Authors
Noel M. Bartlow, David A. Lockner, Nicholas M. Beeler
The role of adsorbed water on the friction of a layer of submicron particles
Anomalously low values of friction observed in layers of submicron particles deformed in simple shear at high slip velocities are explained as the consequence of a one nanometer thick layer of water adsorbed on the particles. The observed transition from normal friction with an apparent coefficient near μ = 0.6 at low slip speeds to a coefficient near μ = 0.3 at higher slip speeds is attributed to
Authors
Charles G. Sammis, David A. Lockner, Ze’ev Reches
Frictional strengths of talc-serpentine and talc-quartz mixtures
Talc is a constituent of faults in a variety of settings, and it may be an effective weakening agent depending on its abundance and distribution within a fault. We conducted frictional strength experiments under hydrothermal conditions to determine the effect of talc on the strengths of synthetic gouges of lizardite and antigorite serpentinites and of quartz. Small amounts of talc weaken serpentin
Authors
Diane E. Moore, D.A. Lockner
Low strength of deep San Andreas fault gouge from SAFOD core
The San Andreas fault accommodates 28–34 mm yr−1 of right lateral motion of the Pacific crustal plate northwestward past the North American plate. In California, the fault is composed of two distinct locked segments that have produced great earthquakes in historical times, separated by a 150-km-long creeping zone. The San Andreas Fault Observatory at Depth (SAFOD) is a scientific borehole located
Authors
David A. Lockner, Carolyn A. Morrow, Diane E. Moore, Stephen H. Hickman
Earthquake rupture at focal depth, part II: mechanics of the 2004 M2.2 earthquake along the Pretorius Fault, TauTona Mine, South Africa
We analyze here the rupture mechanics of the 2004, M2.2 earthquake based on our observations and measurements at focal depth (Part I). This event ruptured the Archean Pretorius fault that has been inactive for at least 2 Ga, and was reactivated due to mining operations down to a depth of 3.6 km depth. Thus, it was expected that the Pretorius fault zone will fail similarly to an intact rock body in
Authors
V. Heesakkers, S. Murphy, D.A. Lockner, Z. Reches
Dependence of frictional strength on compositional variations of Hayward fault rock gouges
The northern termination of the locked portion of the Hayward Fault near Berkeley, California, is found to coincide with the transition from strong Franciscan metagraywacke to melange on the western side of the fault. Both of these units are juxtaposed with various serpentinite, gabbro and graywacke units to the east, suggesting that the gouges formed within the Hayward Fault zone may vary widely
Authors
Carolyn A. Morrow, Diane E. Moore, David A. Lockner
Oscillating load-induced acoustic emission in laboratory experiment
Spatial and temporal patterns of acoustic emission (AE) were studied. A pre-fractured cylinder of granite was loaded in a triaxial machine at 160 MPa confining pressure until stick-slip events occurred. The experiments were conducted at a constant strain rate of 10−7 s−1 that was modulated by small-amplitude sinusoidal oscillations with periods of 175 and 570 seconds. Amplitude of the oscillations
Authors
Alexander Ponomarev, David A. Lockner, S. Stroganova, S. Stanchits, V. Smirnov