Brian D Kilgore
I design and perform lab experiments investigating; the physics of rock friction and earthquake occurrence, rate- and state-dependent friction, earthquake nucleation, and dynamic earthquake rupture propagation. I am specifically interested in precision wide-bandwidth (DC to 1 MHz) measurements of; position, velocity, acceleration, force, strain and non-destructive ultrasonic testing processes.
For more information about the labs, including publications, please visit: https://earthquake.usgs.gov/research/eqproc/rockphysics/
Science and Products
Data from the manuscript: Direct evidence for fluid pressure, dilatancy, and compaction affecting slip in isolated faults
Earthquake instability occurs as a result of strength loss during sliding on a fault. It has been known for over 50 years that fault compaction or dilatancy may cause significant weakening or strengthening by dramatically changing the fluid pressure trapped in faults. Despite this fundamental importance, we have no real understanding of the exact conditions that lead to compaction or dilation duri
Data Release for "Role of Fault Gouge during Interaction between Hydraulic Fracture and a Preexisting Fracture"
Enhanced reservoir connectivity generally requires maximizing the intersection between hydraulic fracture (HF) and preexisting underground natural fractures (NF), while having the hydraulic fracture continue to propagate across the natural fractures. Observations of downhole core samples suggest that these natural fractures are in fact veins filled with minerals such as calcite (Mighani et al., 20
Data Release for: A Wideband Magnetoresistive Sensor for Monitoring Dynamic Fault Slip in Laboratory Fault Friction Experiments
These data are the basis of the figures in the manuscript "A Wideband magnetoresistive sensor for monitoring dynamic fault slip in laboratory fault friction experiments". That report was the result of an investigation of a non-contact, wideband method of sensing dynamic fault slip in laboratory geophysical experiments which employs an inexpensive magnetoresistive sensor, a small neodymium rare ear
Filter Total Items: 23
Effect of thermal and mechanical processes on hydraulic transmissivity evolution
Fracture healing is a critical component of enhanced geothermal systems, the earthquake cycle, and induced seismicity. Accordingly, there is significant interest in understanding the process of healing and its effects on fluid transport. The creation, reactivation, and sustainability of fracture networks depend on complex coupling among thermal, hydraulic, mechanical, and chemical processes. We us
Authors
Tamara Nicole Jeppson, David A. Lockner, Joshua M. Taron, Diane E. Moore, Brian D. Kilgore, Nicholas M. Beeler, Stephen H. Hickman
Apparent age dependence of the fault weakening distance in rock friction
During rock friction experiments at large displacement, room temperature and humidity, and following a hold test, the fracture energy increases approximately as the square of the logarithm of hold duration. While it's been long known that failure strength increases with log hold time, here the slip weakening distance, dh, also increases. The weakening distance increase is large, hundreds of percen
Authors
Nicholas M. Beeler, Allan Rubin, Path Bhattacharya, Brian D. Kilgore, Terry Tullis
Strength recovery and sealing under hydrothermal conditions
While there is significant evidence for healing in natural faults, geothermal reservoirs, and lab experiments, the thermal, hydraulic, mechanical, and chemical interactions that influence healing are poorly understood. We present preliminary results of triaxial slide-hold-slide experiments to constrain rates and mechanisms of healing. Experiments were conducted on gouge composed of Westerly granit
Authors
Tamara Nicole Jeppson, David A. Lockner, Brian D. Kilgore, Nicholas M. Beeler, Joshua M. Taron
Evolution of fluid transmissivity and strength recovery of shear fractures under hydrothermal conditions
Geothermal systems rely on the presence of long-lived and high-volume, permeable fracture systems. The creation, reactivation, and sustainability of these systems depend on complex coupling among thermal, hydraulic, mechanical, and chemical (THMC) processes occurring in geothermal reservoirs. In part due to a paucity of experimental data, the evolution of fractures at geothermal conditions in resp
Authors
Tamara Nicole Jeppson, David A. Lockner, Brian D. Kilgore, Nicholas M. Beeler, Joshua M. Taron
Direct evidence for fluid pressure, dilatancy, and compaction affecting slip in isolated faults
Earthquake instability occurs as a result of strength loss during sliding on a fault. It has been known for over 50 years that fault compaction or dilatancy may cause significant weakening or strengthening by dramatically changing the fluid pressure trapped in faults. Despite this fundamental importance, we have no real understanding of the exact conditions that lead to compaction or dilation duri
Authors
Brooks P. Proctor, David A. Lockner, Brian D. Kilgore, Thomas M. Mitchell, Nicholas M. Beeler
Near-fault velocity spectra from laboratory failures and their relation to natural ground motion
We compared near-fault velocity spectra recorded during laboratory experiments to that of natural earthquakes. We fractured crystalline rock samples at room temperature and intermediate confining pressure (50 MPa). Subsequent slip events were generated on the fracture surfaces under higher confinement (300 MPa). Velocity spectra from rock fracture resemble the inverse frequency (1/f) decay of natu
Authors
Nicholas M. Beeler, David A. Lockner, Brian D. Kilgore, Greg McClaskey
Role of fault gouge during Interaction between hydraulic fracture and a preexisting fracture
Enhanced reservoir connectivity generally requires maximizing the intersection between hydraulic fracture (HF) and preexisting underground natural fractures (NF), while having the hydraulic fracture continue to propagate across the natural fractures. Observations of downhole core samples suggest that these natural fractures are in fact veins filled with minerals such as calcite (Mighani et al., 20
Authors
S. Mighani, David A. Lockner, Brian D. Kilgore, Brian Evans
Interaction between hydraulic fracture and a preexisting fracture under triaxial stress conditions
Enhanced reservoir connectivity generally requires maximizing the intersection between hydraulic fracture (HF) and preexisting underground natural fractures (NF), while having the hydraulic fracture cross the natural fractures (and not arrest). We have studied the interaction between a hydraulic fracture and a polished saw-cut fault. The experiments include a hydraulic fracture initiating from a p
Authors
Saied Mighani, David A. Lockner, Brian D. Kilgore, Farrokh Sheibani, Brian Evans
A wideband magnetoresistive sensor for monitoring dynamic fault slip in laboratory fault friction experiments
A non-contact, wideband method of sensing dynamic fault slip in laboratory geophysical experiments employs an inexpensive magnetoresistive sensor, a small neodymium rare earth magnet, and user built application-specific wideband signal conditioning. The magnetoresistive sensor generates a voltage proportional to the changing angles of magnetic flux lines, generated by differential motion or rotati
Authors
Brian D. Kilgore
Rock friction under variable normal stress
This study is to determine the detailed response of shear strength and other fault properties to changes in normal stress at room temperature using dry initially bare rock surfaces of granite at normal stresses between 5 and 7 MPa. Rapid normal stress changes result in gradual, approximately exponential changes in shear resistance with fault slip. The characteristic length of the exponential chang
Authors
Brian D. Kilgore, Nicholas M. Beeler, Julian C. Lozos, David Oglesby
The transition from frictional sliding to shear melting in laboratory stick-slip experiments
No abstract available
Authors
David A. Lockner, Brian D. Kilgore, Nicholas M. Beeler, Diane E. Moore
Earthquake source properties from instrumented laboratory stick-slip
Stick-slip experiments were performed to determine the influence of the testing apparatus on source properties, develop methods to relate stick-slip to natural earthquakes and examine the hypothesis of McGarr [2012] that the product of stiffness, k, and slip duration, Δt, is scale-independent and the same order as for earthquakes. The experiments use the double-direct shear geometry, Sierra White
Authors
Brian D. Kilgore, Arthur F. McGarr, Nicholas M. Beeler, David A. Lockner
Science and Products
- Data
Data from the manuscript: Direct evidence for fluid pressure, dilatancy, and compaction affecting slip in isolated faults
Earthquake instability occurs as a result of strength loss during sliding on a fault. It has been known for over 50 years that fault compaction or dilatancy may cause significant weakening or strengthening by dramatically changing the fluid pressure trapped in faults. Despite this fundamental importance, we have no real understanding of the exact conditions that lead to compaction or dilation duriData Release for "Role of Fault Gouge during Interaction between Hydraulic Fracture and a Preexisting Fracture"
Enhanced reservoir connectivity generally requires maximizing the intersection between hydraulic fracture (HF) and preexisting underground natural fractures (NF), while having the hydraulic fracture continue to propagate across the natural fractures. Observations of downhole core samples suggest that these natural fractures are in fact veins filled with minerals such as calcite (Mighani et al., 20Data Release for: A Wideband Magnetoresistive Sensor for Monitoring Dynamic Fault Slip in Laboratory Fault Friction Experiments
These data are the basis of the figures in the manuscript "A Wideband magnetoresistive sensor for monitoring dynamic fault slip in laboratory fault friction experiments". That report was the result of an investigation of a non-contact, wideband method of sensing dynamic fault slip in laboratory geophysical experiments which employs an inexpensive magnetoresistive sensor, a small neodymium rare ear - Publications
Filter Total Items: 23
Effect of thermal and mechanical processes on hydraulic transmissivity evolution
Fracture healing is a critical component of enhanced geothermal systems, the earthquake cycle, and induced seismicity. Accordingly, there is significant interest in understanding the process of healing and its effects on fluid transport. The creation, reactivation, and sustainability of fracture networks depend on complex coupling among thermal, hydraulic, mechanical, and chemical processes. We usAuthorsTamara Nicole Jeppson, David A. Lockner, Joshua M. Taron, Diane E. Moore, Brian D. Kilgore, Nicholas M. Beeler, Stephen H. HickmanApparent age dependence of the fault weakening distance in rock friction
During rock friction experiments at large displacement, room temperature and humidity, and following a hold test, the fracture energy increases approximately as the square of the logarithm of hold duration. While it's been long known that failure strength increases with log hold time, here the slip weakening distance, dh, also increases. The weakening distance increase is large, hundreds of percenAuthorsNicholas M. Beeler, Allan Rubin, Path Bhattacharya, Brian D. Kilgore, Terry TullisStrength recovery and sealing under hydrothermal conditions
While there is significant evidence for healing in natural faults, geothermal reservoirs, and lab experiments, the thermal, hydraulic, mechanical, and chemical interactions that influence healing are poorly understood. We present preliminary results of triaxial slide-hold-slide experiments to constrain rates and mechanisms of healing. Experiments were conducted on gouge composed of Westerly granitAuthorsTamara Nicole Jeppson, David A. Lockner, Brian D. Kilgore, Nicholas M. Beeler, Joshua M. TaronEvolution of fluid transmissivity and strength recovery of shear fractures under hydrothermal conditions
Geothermal systems rely on the presence of long-lived and high-volume, permeable fracture systems. The creation, reactivation, and sustainability of these systems depend on complex coupling among thermal, hydraulic, mechanical, and chemical (THMC) processes occurring in geothermal reservoirs. In part due to a paucity of experimental data, the evolution of fractures at geothermal conditions in respAuthorsTamara Nicole Jeppson, David A. Lockner, Brian D. Kilgore, Nicholas M. Beeler, Joshua M. TaronDirect evidence for fluid pressure, dilatancy, and compaction affecting slip in isolated faults
Earthquake instability occurs as a result of strength loss during sliding on a fault. It has been known for over 50 years that fault compaction or dilatancy may cause significant weakening or strengthening by dramatically changing the fluid pressure trapped in faults. Despite this fundamental importance, we have no real understanding of the exact conditions that lead to compaction or dilation duriAuthorsBrooks P. Proctor, David A. Lockner, Brian D. Kilgore, Thomas M. Mitchell, Nicholas M. BeelerNear-fault velocity spectra from laboratory failures and their relation to natural ground motion
We compared near-fault velocity spectra recorded during laboratory experiments to that of natural earthquakes. We fractured crystalline rock samples at room temperature and intermediate confining pressure (50 MPa). Subsequent slip events were generated on the fracture surfaces under higher confinement (300 MPa). Velocity spectra from rock fracture resemble the inverse frequency (1/f) decay of natuAuthorsNicholas M. Beeler, David A. Lockner, Brian D. Kilgore, Greg McClaskeyRole of fault gouge during Interaction between hydraulic fracture and a preexisting fracture
Enhanced reservoir connectivity generally requires maximizing the intersection between hydraulic fracture (HF) and preexisting underground natural fractures (NF), while having the hydraulic fracture continue to propagate across the natural fractures. Observations of downhole core samples suggest that these natural fractures are in fact veins filled with minerals such as calcite (Mighani et al., 20AuthorsS. Mighani, David A. Lockner, Brian D. Kilgore, Brian EvansInteraction between hydraulic fracture and a preexisting fracture under triaxial stress conditions
Enhanced reservoir connectivity generally requires maximizing the intersection between hydraulic fracture (HF) and preexisting underground natural fractures (NF), while having the hydraulic fracture cross the natural fractures (and not arrest). We have studied the interaction between a hydraulic fracture and a polished saw-cut fault. The experiments include a hydraulic fracture initiating from a pAuthorsSaied Mighani, David A. Lockner, Brian D. Kilgore, Farrokh Sheibani, Brian EvansA wideband magnetoresistive sensor for monitoring dynamic fault slip in laboratory fault friction experiments
A non-contact, wideband method of sensing dynamic fault slip in laboratory geophysical experiments employs an inexpensive magnetoresistive sensor, a small neodymium rare earth magnet, and user built application-specific wideband signal conditioning. The magnetoresistive sensor generates a voltage proportional to the changing angles of magnetic flux lines, generated by differential motion or rotatiAuthorsBrian D. KilgoreRock friction under variable normal stress
This study is to determine the detailed response of shear strength and other fault properties to changes in normal stress at room temperature using dry initially bare rock surfaces of granite at normal stresses between 5 and 7 MPa. Rapid normal stress changes result in gradual, approximately exponential changes in shear resistance with fault slip. The characteristic length of the exponential changAuthorsBrian D. Kilgore, Nicholas M. Beeler, Julian C. Lozos, David OglesbyThe transition from frictional sliding to shear melting in laboratory stick-slip experiments
No abstract availableAuthorsDavid A. Lockner, Brian D. Kilgore, Nicholas M. Beeler, Diane E. MooreEarthquake source properties from instrumented laboratory stick-slip
Stick-slip experiments were performed to determine the influence of the testing apparatus on source properties, develop methods to relate stick-slip to natural earthquakes and examine the hypothesis of McGarr [2012] that the product of stiffness, k, and slip duration, Δt, is scale-independent and the same order as for earthquakes. The experiments use the double-direct shear geometry, Sierra WhiteAuthorsBrian D. Kilgore, Arthur F. McGarr, Nicholas M. Beeler, David A. Lockner