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
Filter Total Items: 23
Gallery of melt textures developed in Westerly Granite during high-pressure triaxial friction experiments
IntroductionMelting occurred during stick-slip faulting of granite blocks sheared at room-dry, room-temperature conditions in a triaxial apparatus at 200–400 megapascals (MPa) confining pressure. Petrographic examinations of melt textures focused largely on the 400-MPa run products. This report presents an overview of the petrographic data collected on those samples, followed by brief descriptions
Authors
Diane E. Moore, David A. Lockner, Brian D. Kilgore, Nicholas M. Beeler
A robust calibration technique for acoustic emission systems based on momentum transfer from a ball drop
We describe a technique to estimate the seismic moment of acoustic emissions and other extremely small seismic events. Unlike previous calibration techniques, it does not require modeling of the wave propagation, sensor response, or signal conditioning. Rather, this technique calibrates the recording system as a whole and uses a ball impact as a reference source or empirical Green’s function. To c
Authors
Gregory C. McLaskey, David A. Lockner, Brian D. Kilgore, Nicholas M. Beeler
Slip-pulse rupture behavior on a 2 meter granite fault
We describe observations of dynamic rupture events that spontaneously arise on meter-scale laboratory earthquake experiments. While low-frequency slip of the granite sample occurs in a relatively uniform and crack-like manner, instruments capable of detecting high frequency motions show that some parts of the fault slip abruptly (velocity >100 mm∙s-1, acceleration >20 km∙s-2) while the majority of
Authors
Gregory C. McLaskey, Brian D. Kilgore, Nicholas M. Beeler
Laboratory generated M -6 earthquakes
We consider whether mm-scale earthquake-like seismic events generated in laboratory experiments are consistent with our understanding of the physics of larger earthquakes. This work focuses on a population of 48 very small shocks that are foreshocks and aftershocks of stick–slip events occurring on a 2.0 m by 0.4 m simulated strike-slip fault cut through a large granite sample. Unlike the larger s
Authors
Gregory C. McLaskey, Brian D. Kilgore, David A. Lockner, Nicholas M. Beeler
High-frequency imaging of elastic contrast and contact area with implications for naturally observed changes in fault properties
During localized slip of a laboratory fault we simultaneously measure the contact area and the dynamic fault normal elastic stiffness. One objective is to determine conditions where stiffness may be used to infer changes in area of contact during sliding on nontransparent fault surfaces. Slip speeds between 0.01 and 10 µm/s and normal stresses between 1 and 2.5 MPa were imposed during velocity ste
Authors
Kohei Nagata, Brian D. Kilgore, Nicholas M. Beeler, Masao Nakatani
Laboratory constraints on models of earthquake recurrence
In this study, rock friction ‘stick-slip’ experiments are used to develop constraints on models of earthquake recurrence. Constant-rate loading of bare rock surfaces in high quality experiments produces stick-slip recurrence that is periodic at least to second order. When the loading rate is varied, recurrence is approximately inversely proportional to loading rate. These laboratory events initiat
Authors
Nicholas M. Beeler, Terry Tullis, Jenni Junger, Brian D. Kilgore, David L. Goldsby
Foreshocks during the nucleation of stick-slip instability
We report on laboratory experiments which investigate interactions between aseismic slip, stress changes, and seismicity on a critically stressed fault during the nucleation of stick-slip instability. We monitor quasi-static and dynamic changes in local shear stress and fault slip with arrays of gages deployed along a simulated strike-slip fault (2 m long and 0.4 m deep) in a saw cut sample of Sie
Authors
Gregory C. McLaskey, Brian D. Kilgore
Observed source parameters for dynamic rupture with non-uniform initial stressand relatively high fracture energy
We have conducted dynamic rupture propagation experiments to establish the relations between in-source stress drop, fracture energy and the resulting particle velocity during slip of an unconfined 2 m long laboratory fault at normal stresses between 4 and 8 MPa. To produce high fracture energy in the source we use a rough fault that has a large slip weakening distance. An artifact of the high frac
Authors
Nicholas M. Beeler, Brian D. Kilgore, Arthur F. McGarr, Jon Peter B. Fletcher, John R. Evans, Steven R. Baker
Laboratory observations of fault strength in response to changes in normal stress
Changes in fault normal stress can either inhibit or promote rupture propagation, depending on the fault geometry and on how fault shear strength varies in response to the normal stress change. A better understanding of this dependence will lead to improved earthquake simulation techniques, and ultimately, improved earthquake hazard mitigation efforts. We present the results of new laboratory expe
Authors
Brian D. Kilgore, Julian Lozos, Nicholas M. Beeler, David Oglesby
Velocity dependent friction of granite over a wide range of conditions
Direct shear sliding experiments on bare ground surfaces of Westerly granite have been conducted over an exceptionally wide range of sliding rates (10−4 µm/s to 10³ µm/s) at unconfined normal stresses (σn) of 5, 15, 30, 70, and 150 MPa. A new sample configuration was developed that permitted measurements at normal stresses of 70 and 150 MPa without immediate sample failure. Measurements of steady-
Authors
Brian D. Kilgore, Michael L. Blanpied, James H. Dieterich
Scaling of the critical slip distance for seismic faulting with shear strain in fault zones
THEORETICAL and experimentally based laws for seismic faulting contain a critical slip distance1-5, Dc, which is the slip over which strength breaks down during earthquake nucleation. On an earthquake-generating fault, this distance plays a key role in determining the rupture nucleation dimension6, the amount of premonitory and post-seismic slip7-10, and the maximum seismic ground acceleration1,11
Authors
Chris Marone, Brian D. Kilgore
Science and Products
Filter Total Items: 23
Gallery of melt textures developed in Westerly Granite during high-pressure triaxial friction experiments
IntroductionMelting occurred during stick-slip faulting of granite blocks sheared at room-dry, room-temperature conditions in a triaxial apparatus at 200–400 megapascals (MPa) confining pressure. Petrographic examinations of melt textures focused largely on the 400-MPa run products. This report presents an overview of the petrographic data collected on those samples, followed by brief descriptions
Authors
Diane E. Moore, David A. Lockner, Brian D. Kilgore, Nicholas M. Beeler
A robust calibration technique for acoustic emission systems based on momentum transfer from a ball drop
We describe a technique to estimate the seismic moment of acoustic emissions and other extremely small seismic events. Unlike previous calibration techniques, it does not require modeling of the wave propagation, sensor response, or signal conditioning. Rather, this technique calibrates the recording system as a whole and uses a ball impact as a reference source or empirical Green’s function. To c
Authors
Gregory C. McLaskey, David A. Lockner, Brian D. Kilgore, Nicholas M. Beeler
Slip-pulse rupture behavior on a 2 meter granite fault
We describe observations of dynamic rupture events that spontaneously arise on meter-scale laboratory earthquake experiments. While low-frequency slip of the granite sample occurs in a relatively uniform and crack-like manner, instruments capable of detecting high frequency motions show that some parts of the fault slip abruptly (velocity >100 mm∙s-1, acceleration >20 km∙s-2) while the majority of
Authors
Gregory C. McLaskey, Brian D. Kilgore, Nicholas M. Beeler
Laboratory generated M -6 earthquakes
We consider whether mm-scale earthquake-like seismic events generated in laboratory experiments are consistent with our understanding of the physics of larger earthquakes. This work focuses on a population of 48 very small shocks that are foreshocks and aftershocks of stick–slip events occurring on a 2.0 m by 0.4 m simulated strike-slip fault cut through a large granite sample. Unlike the larger s
Authors
Gregory C. McLaskey, Brian D. Kilgore, David A. Lockner, Nicholas M. Beeler
High-frequency imaging of elastic contrast and contact area with implications for naturally observed changes in fault properties
During localized slip of a laboratory fault we simultaneously measure the contact area and the dynamic fault normal elastic stiffness. One objective is to determine conditions where stiffness may be used to infer changes in area of contact during sliding on nontransparent fault surfaces. Slip speeds between 0.01 and 10 µm/s and normal stresses between 1 and 2.5 MPa were imposed during velocity ste
Authors
Kohei Nagata, Brian D. Kilgore, Nicholas M. Beeler, Masao Nakatani
Laboratory constraints on models of earthquake recurrence
In this study, rock friction ‘stick-slip’ experiments are used to develop constraints on models of earthquake recurrence. Constant-rate loading of bare rock surfaces in high quality experiments produces stick-slip recurrence that is periodic at least to second order. When the loading rate is varied, recurrence is approximately inversely proportional to loading rate. These laboratory events initiat
Authors
Nicholas M. Beeler, Terry Tullis, Jenni Junger, Brian D. Kilgore, David L. Goldsby
Foreshocks during the nucleation of stick-slip instability
We report on laboratory experiments which investigate interactions between aseismic slip, stress changes, and seismicity on a critically stressed fault during the nucleation of stick-slip instability. We monitor quasi-static and dynamic changes in local shear stress and fault slip with arrays of gages deployed along a simulated strike-slip fault (2 m long and 0.4 m deep) in a saw cut sample of Sie
Authors
Gregory C. McLaskey, Brian D. Kilgore
Observed source parameters for dynamic rupture with non-uniform initial stressand relatively high fracture energy
We have conducted dynamic rupture propagation experiments to establish the relations between in-source stress drop, fracture energy and the resulting particle velocity during slip of an unconfined 2 m long laboratory fault at normal stresses between 4 and 8 MPa. To produce high fracture energy in the source we use a rough fault that has a large slip weakening distance. An artifact of the high frac
Authors
Nicholas M. Beeler, Brian D. Kilgore, Arthur F. McGarr, Jon Peter B. Fletcher, John R. Evans, Steven R. Baker
Laboratory observations of fault strength in response to changes in normal stress
Changes in fault normal stress can either inhibit or promote rupture propagation, depending on the fault geometry and on how fault shear strength varies in response to the normal stress change. A better understanding of this dependence will lead to improved earthquake simulation techniques, and ultimately, improved earthquake hazard mitigation efforts. We present the results of new laboratory expe
Authors
Brian D. Kilgore, Julian Lozos, Nicholas M. Beeler, David Oglesby
Velocity dependent friction of granite over a wide range of conditions
Direct shear sliding experiments on bare ground surfaces of Westerly granite have been conducted over an exceptionally wide range of sliding rates (10−4 µm/s to 10³ µm/s) at unconfined normal stresses (σn) of 5, 15, 30, 70, and 150 MPa. A new sample configuration was developed that permitted measurements at normal stresses of 70 and 150 MPa without immediate sample failure. Measurements of steady-
Authors
Brian D. Kilgore, Michael L. Blanpied, James H. Dieterich
Scaling of the critical slip distance for seismic faulting with shear strain in fault zones
THEORETICAL and experimentally based laws for seismic faulting contain a critical slip distance1-5, Dc, which is the slip over which strength breaks down during earthquake nucleation. On an earthquake-generating fault, this distance plays a key role in determining the rupture nucleation dimension6, the amount of premonitory and post-seismic slip7-10, and the maximum seismic ground acceleration1,11
Authors
Chris Marone, Brian D. Kilgore