David A Lockner
David Lockner is a geophysicist in the Earthquake Science Center.
Science and Products
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Dependence of frictional strength on compositional variations of Hayward fault rock gouges 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...
Authors
Carolyn A. Morrow, Diane E. Moore, David A. Lockner
Oscillating load-induced acoustic emission in laboratory experiment 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...
Authors
Alexander Ponomarev, David A. Lockner, S. Stroganova, S. Stanchits, V. Smirnov
Effect of clay content and mineralogy on frictional sliding behavior of simulated gouges: binary and ternary mixtures of quartz, illite, and montmorillonite 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...
Authors
Sheryl Tembe, David A. Lockner, Teng-Fong Wong
Fault weakening and earthquake instability by powder lubrication 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...
Authors
Z. Reches, D.A. Lockner
Fault-related clay authigenesis along the Moab Fault: Implications for calculations of fault rock composition and mechanical and hydrologic fault zone properties 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...
Authors
J.G. Solum, N.C. Davatzes, D.A. Lockner
Anomalously low strength of serpentinite sheared against granite and implications for creep on the Hayward and Calaveras Faults 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...
Authors
Diane E. Moore, David A. Lockner, David A. Ponce
Science and Products
Filter Total Items: 14
No Result Found
Filter Total Items: 115
Dependence of frictional strength on compositional variations of Hayward fault rock gouges 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...
Authors
Carolyn A. Morrow, Diane E. Moore, David A. Lockner
Oscillating load-induced acoustic emission in laboratory experiment 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...
Authors
Alexander Ponomarev, David A. Lockner, S. Stroganova, S. Stanchits, V. Smirnov
Effect of clay content and mineralogy on frictional sliding behavior of simulated gouges: binary and ternary mixtures of quartz, illite, and montmorillonite 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...
Authors
Sheryl Tembe, David A. Lockner, Teng-Fong Wong
Fault weakening and earthquake instability by powder lubrication 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...
Authors
Z. Reches, D.A. Lockner
Fault-related clay authigenesis along the Moab Fault: Implications for calculations of fault rock composition and mechanical and hydrologic fault zone properties 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...
Authors
J.G. Solum, N.C. Davatzes, D.A. Lockner
Anomalously low strength of serpentinite sheared against granite and implications for creep on the Hayward and Calaveras Faults 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...
Authors
Diane E. Moore, David A. Lockner, David A. Ponce