Nicholas (Nick) M Beeler
Nick Beeler is a scientist in the Earthquake Science Center.
Science and Products
Filter Total Items: 58
A note on contact stress and closure in models of rock joints and faults
We have re-examined asperity deformation predicted by joint closure models based on Greenwood and Williamson [1966] which use a statistical representation of loaded, rough surfaces. Although such models assume small elastic strains within contacting asperities (Hertzian contact) and well predict the observed dependence of closure on normal stress, large elastic normal strains measured in experimen
Authors
N.M. Beeler, S.H. Hickman
Earthquake stress drop and laboratory-inferred interseismic strength recovery
We determine the scaling relationships between earthquake stress drop and recurrence interval tr that are implied by laboratory-measured fault strength. We assume that repeating earthquakes can be simulated by stick-slip sliding using a spring and slider block model. Simulations with static/kinetic strength, time-dependent strength, and rate- and state-variable-dependent strength indicate that the
Authors
N.M. Beeler, S.H. Hickman, T.-F. Wong
Pore fluid pressure, apparent friction, and Coulomb failure
Many recent studies of stress-triggered seismicity rely on a fault failure model with a single free parameter, the apparent coefficient of friction, presumed to be a material constant with possible values 0 ≤ μ′ ≤ 1. These studies may present a misleading view of fault strength and the role of pore fluid pressure in earthquake failure. The parameter μ′ is intended to incorporate the effects of bot
Authors
N.M. Beeler, R. W. Simpson, S.H. Hickman, D. A. Lockner
Premonitory slip and tidal triggering of earthquakes
We have conducted a series of laboratory simulations of earthquakes using granite cylinders containing precut bare fault surfaces at 50 MPa confining pressure. Axial shortening rates between 10−4and 10−6 mm/s were imposed to simulate tectonic loading. Average loading rate was then modulated by the addition of a small-amplitude sine wave to simulate periodic loading due to Earth tides or other sour
Authors
D. A. Lockner, N.M. Beeler
Earthquake triggering by transient and static deformations
Observational evidence for both static and transient near-field and far-field triggered seismicity are explained in terms of a frictional instability model, based on a single degree of freedom spring-slider system and rate- and state-dependent frictional constitutive equations. In this study a triggered earthquake is one whose failure time has been advanced by Δt (clock advance) due to a stress pe
Authors
J. Gomberg, N.M. Beeler, M.L. Blanpied, P. Bodin
The roles of time and displacement in velocity-dependent volumetric strain of fault zones
The relationship between measured friction??A and volumetric strain during frictional sliding was determined using a rate and state variable dependent friction constitutive equation, a common work balance relating friction and volume change, and two types of experimental faults: initially bare surfaces of Westerly granite and rock surfaces separated by a 1 mm layer of < 90 ??m Westerly granite gou
Authors
N.M. Beeler, T.E. Tullis
Transient triggering of near and distant earthquakes
We demonstrate qualitatively that frictional instability theory provides a context for understanding how earthquakes may be triggered by transient loads associated with seismic waves from near and distance earthquakes. We assume that earthquake triggering is a stick-slip process and test two hypotheses about the effect of transients on the timing of instabilities using a simple spring-slider model
Authors
J. Gomberg, M.L. Blanpied, N.M. Beeler
Frictional behavior of large displacement experimental faults
The coefficient of friction and velocity dependence of friction of initially bare surfaces and 1-mm-thick simulated fault gouges (< 90 ??m) of Westerly granite were determined as a function of displacement to >400 mm at 25??C and 25 MPa normal stress. Steady state negative friction velocity dependence and a steady state fault zone microstructure are achieved after ???18 mm displacement, and an app
Authors
N.M. Beeler, T.E. Tullis, M.L. Blanpied, J.D. Weeks
Self-healing slip pulses in dynamic rupture models due to velocity-dependent strength
Seismological observations of short slip duration on faults (short rise time on seismograms) during earthquakes are not consistent with conventional crack models of dynamic rupture and fault slip. In these models, the leading edge of rupture stops only when a strong region is encountered, and slip at an interior point ceases only when waves from the stopped edge of slip propagate back to that poin
Authors
N.M. Beeler, T.E. Tullis
Implications of Coulomb plasticity for the velocity dependence of experimental faults
Simulated fault gouges often deform more stably than initially bare surfaces of the same composition. It is important to understand why the sliding stability is enhanced because the presence of gouge on natural faults may have the same effect as seen in experiments, and thus explain the absence of earthquakes at shallow depths. Gouge stabilization in experiments has been attributed to positive con
Authors
N.M. Beeler, T.E. Tullis
Science and Products
Filter Total Items: 58
A note on contact stress and closure in models of rock joints and faults
We have re-examined asperity deformation predicted by joint closure models based on Greenwood and Williamson [1966] which use a statistical representation of loaded, rough surfaces. Although such models assume small elastic strains within contacting asperities (Hertzian contact) and well predict the observed dependence of closure on normal stress, large elastic normal strains measured in experimen
Authors
N.M. Beeler, S.H. Hickman
Earthquake stress drop and laboratory-inferred interseismic strength recovery
We determine the scaling relationships between earthquake stress drop and recurrence interval tr that are implied by laboratory-measured fault strength. We assume that repeating earthquakes can be simulated by stick-slip sliding using a spring and slider block model. Simulations with static/kinetic strength, time-dependent strength, and rate- and state-variable-dependent strength indicate that the
Authors
N.M. Beeler, S.H. Hickman, T.-F. Wong
Pore fluid pressure, apparent friction, and Coulomb failure
Many recent studies of stress-triggered seismicity rely on a fault failure model with a single free parameter, the apparent coefficient of friction, presumed to be a material constant with possible values 0 ≤ μ′ ≤ 1. These studies may present a misleading view of fault strength and the role of pore fluid pressure in earthquake failure. The parameter μ′ is intended to incorporate the effects of bot
Authors
N.M. Beeler, R. W. Simpson, S.H. Hickman, D. A. Lockner
Premonitory slip and tidal triggering of earthquakes
We have conducted a series of laboratory simulations of earthquakes using granite cylinders containing precut bare fault surfaces at 50 MPa confining pressure. Axial shortening rates between 10−4and 10−6 mm/s were imposed to simulate tectonic loading. Average loading rate was then modulated by the addition of a small-amplitude sine wave to simulate periodic loading due to Earth tides or other sour
Authors
D. A. Lockner, N.M. Beeler
Earthquake triggering by transient and static deformations
Observational evidence for both static and transient near-field and far-field triggered seismicity are explained in terms of a frictional instability model, based on a single degree of freedom spring-slider system and rate- and state-dependent frictional constitutive equations. In this study a triggered earthquake is one whose failure time has been advanced by Δt (clock advance) due to a stress pe
Authors
J. Gomberg, N.M. Beeler, M.L. Blanpied, P. Bodin
The roles of time and displacement in velocity-dependent volumetric strain of fault zones
The relationship between measured friction??A and volumetric strain during frictional sliding was determined using a rate and state variable dependent friction constitutive equation, a common work balance relating friction and volume change, and two types of experimental faults: initially bare surfaces of Westerly granite and rock surfaces separated by a 1 mm layer of < 90 ??m Westerly granite gou
Authors
N.M. Beeler, T.E. Tullis
Transient triggering of near and distant earthquakes
We demonstrate qualitatively that frictional instability theory provides a context for understanding how earthquakes may be triggered by transient loads associated with seismic waves from near and distance earthquakes. We assume that earthquake triggering is a stick-slip process and test two hypotheses about the effect of transients on the timing of instabilities using a simple spring-slider model
Authors
J. Gomberg, M.L. Blanpied, N.M. Beeler
Frictional behavior of large displacement experimental faults
The coefficient of friction and velocity dependence of friction of initially bare surfaces and 1-mm-thick simulated fault gouges (< 90 ??m) of Westerly granite were determined as a function of displacement to >400 mm at 25??C and 25 MPa normal stress. Steady state negative friction velocity dependence and a steady state fault zone microstructure are achieved after ???18 mm displacement, and an app
Authors
N.M. Beeler, T.E. Tullis, M.L. Blanpied, J.D. Weeks
Self-healing slip pulses in dynamic rupture models due to velocity-dependent strength
Seismological observations of short slip duration on faults (short rise time on seismograms) during earthquakes are not consistent with conventional crack models of dynamic rupture and fault slip. In these models, the leading edge of rupture stops only when a strong region is encountered, and slip at an interior point ceases only when waves from the stopped edge of slip propagate back to that poin
Authors
N.M. Beeler, T.E. Tullis
Implications of Coulomb plasticity for the velocity dependence of experimental faults
Simulated fault gouges often deform more stably than initially bare surfaces of the same composition. It is important to understand why the sliding stability is enhanced because the presence of gouge on natural faults may have the same effect as seen in experiments, and thus explain the absence of earthquakes at shallow depths. Gouge stabilization in experiments has been attributed to positive con
Authors
N.M. Beeler, T.E. Tullis