scholarly journals Slip event propagation direction in transition region of low surface slope

2005 ◽  
Vol 40 ◽  
pp. 43-46 ◽  
Author(s):  
Johannes Weertman
Keyword(s):  
Frictional Resistance ◽  
Propagation Direction ◽  
Surface Slope ◽  
Ice Shelf ◽  
Stick Slip ◽  
Sliding Motion ◽  
Normal Traction ◽  
Slip Event ◽  
Edge Dislocations ◽  
Basal Till

AbstractThe base of the ice in the transition zone between an ice stream and an ice shelf is likely to be well lubricated by broadly distributed water, a condition which should permit fast sliding motion. It has been observed that motion takes place not smoothly but by localized stick–slip events that propagate in the downstream direction towards the ice shelf and at velocities approximately that expected for shear wave velocity of the basal till. Thus slip packets of gliding edge dislocations are likely to move at the base. I show here that subsonic dislocations should move upstream, rather than downstream, if frictional resistance is determined by normal traction stress change at the base. Transonic dislocations are expected to move in the downstream direction. However, if frictional resistance is lowered by hydrostatic pressure reduction at the base, the subsonic dislocation should move downstream.

Influence of the Structure of a Gouge-Filled Fault on the Parameters of Acoustic Emission

2019 ◽  
Vol 105 (5) ◽  
pp. 759-765 ◽  
Author(s):  
Alexey A. Ostapchuk ◽  
Kseniya G. Morozova ◽  
Dmitry V. Pavlov
Keyword(s):  
Acoustic Emission ◽  
Laboratory Experiments ◽  
Shear Crack ◽  
Kinematic Parameters ◽  
Stick Slip ◽  
Omori Law ◽  
Shear Loads ◽  
Initial Stage ◽  
Slip Event ◽  
Model Setup

Presented are the results of laboratory experiments on investigating manifestations of acoustic emission (AE) of a gouge-filled fault during stick-slip. The laboratory experiments were held at the slider-model setup, when a granite block slides along a rough granite base under normal and shear loads. In the course of experiments we altered the structure of the two-component filler of the fault and focused on variations of the AE parameters. The kinematic parameters of fault slip events in all the realizations remained approximately the same. The eff ect of gouge structure on the statistics of AE has been revealed. An alteration of proportion of quartz sand / glass beads in the filler of the fault was accompanied by an alteration of the b-value of frequency-energy distribution from 0.53 to 0.85, and the p-value of Omori law from 1.00 to 2.06. Also, it has been demonstrated that the nucleation of a slip event is accompanied by an alteration of the mechanism of AE generation – at the initial stage the 'tensile crack' signals prevailed, while at the final stage – the 'shear crack' signals did. The alteration of AE genesis manifested vividly in a corresponding alteration of the emitted waveforms for all the realizations.

scholarly journals Results From The Amery Ice Shelf Project

1982 ◽  
Vol 3 ◽  
pp. 36-41 ◽  
Author(s):  
W. F. Budd ◽  
M. J. Corry ◽  
T. H. Jacka
Keyword(s):  
High Strain ◽  
Ice Core ◽  
Snow Accumulation ◽  
Ice Thickness ◽  
Surface Slope ◽  
Ice Shelf ◽  
Substantial Growth ◽  
Basal Ice ◽  
Amery Ice Shelf ◽  
Comprehensive Study

The major results from a comprehensive study of the Amery Ice Shelf are presented, following the work of a wintering expedition in 1968 and supplemented by further measurements during the summer seasons of 1969 to 1971. The Programme included ice-core drilling, oversnow surveys for ice movement and optical levelling, ice-thickness sounding, and measurements of snow accumulation. The new data obtained provide the basis for a more accurate assessment of the mass balance and dynamics of the ice shelf than was possible from the earlier surveys. The results indicate a substantial growth of basal ice under the ice shelf inland where the ice thickness is greater than 450 m. Further towards the ice front the high strain thinning is approximately balanced by the horizontal ice advection. The velocity distribution over the ice shelf is primarily governed by a substantial surface slope towards the ice front and high restraining shear stress along the sides.

scholarly journals Simulated Nanoscale Peeling Process of Monolayer Graphene Sheet: Effect of Edge Structure and Lifting Position

2010 ◽  
Vol 2010 ◽  
pp. 1-12 ◽  
Author(s):  
Naruo Sasaki ◽  
Hideaki Okamoto ◽  
Shingen Masuda ◽  
Kouji Miura ◽  
Noriaki Itamura
Keyword(s):  
Graphene Sheet ◽  
Atomic Scale ◽  
Monolayer Graphene ◽  
Lattice Period ◽  
Force Curve ◽  
Stick Slip ◽  
Edge Structure ◽  
Sliding Motion ◽  
Peeling Process ◽  
Surface Contact

The nanoscale peeling of the graphene sheet on the graphite surface is numerically studied by molecular mechanics simulation. For center-lifting case, the successive partial peelings of the graphene around the lifting center appear as discrete jumps in the force curve, which induce the arched deformation of the graphene sheet. For edge-lifting case, marked atomic-scale friction of the graphene sheet during the nanoscale peeling process is found. During the surface contact, the graphene sheet takes the atomic-scale sliding motion. The period of the peeling force curve during the surface contact decreases to the lattice period of the graphite. During the line contact, the graphene sheet also takes the stick-slip sliding motion. These findings indicate the possibility of not only the direct observation of the atomic-scale friction of the graphene sheet at the tip/surface interface but also the identification of the lattice orientation and the edge structure of the graphene sheet.

scholarly journals On the question of whether lubricants fluidize in stick–slip friction

2015 ◽  
Vol 112 (23) ◽  
pp. 7117-7122 ◽  
Author(s):  
Irit Rosenhek-Goldian ◽  
Nir Kampf ◽  
Arie Yeredor ◽  
Jacob Klein
Keyword(s):  
Surface Force ◽  
Lubricant Film ◽  
Force Balance ◽  
Smooth Surfaces ◽  
Stick Slip ◽  
Lubricant Films ◽  
Slip Event ◽  
Stick Slip Motion ◽  
Molecular Layers ◽  
Slip Motion

Intermittent sliding (stick–slip motion) between solids is commonplace (e.g., squeaking hinges), even in the presence of lubricants, and is believed to occur by shear-induced fluidization of the lubricant film (slip), followed by its resolidification (stick). Using a surface force balance, we measure how the thickness of molecularly thin, model lubricant films (octamethylcyclotetrasiloxane) varies in stick–slip sliding between atomically smooth surfaces during the fleeting (ca. 20 ms) individual slip events. Shear fluidization of a film of five to six molecular layers during an individual slip event should result in film dilation of 0.4–0.5 nm, but our results show that, within our resolution of ca. 0.1 nm, slip of the surfaces is not correlated with any dilation of the intersurface gap. This reveals that, unlike what is commonly supposed, slip does not occur by such shear melting, and indicates that other mechanisms, such as intralayer slip within the lubricant film, or at its interface with the confining surfaces, may be the dominant dissipation modes.

A Simplified Model of the Base-Excited Coulomb Friction Oscillator With Contact Compliance and Inertia

Volume 1 ◽  
2004 ◽  
Author(s):  
Jin-Wei Liang
Keyword(s):  
Approximate Model ◽  
Contact Dynamics ◽  
Contact Model ◽  
Order System ◽  
Stick Slip ◽  
Sliding Motion ◽  
Contact Compliance ◽  
Friction Oscillator ◽  
Rigid Contact ◽  
Two Degree Of Freedom

This work investigates a base-excited Coulomb oscillator with contact compliance and inertia. The full-order system is a two degree-of-freedom (DOF) problem. The study first shows that two existing approximate models, including the rigid-contact model (RCM) and the compliant-contact model (CCM) cannot closely capture the dynamical characteristics of the global pure-sliding responses of the full-order system (FOS). To complement for this, this study proposes a new approximate model denoted as the reduced-order system (ROS), which is especially suitable for studying the contact dynamics subjected to the global pure-sliding motion. Numerical results show that the ROS not only has the merit of simplicity can also reliably depict the global pure-sliding features of the FOS. Furthermore, relevant stick-slip phenomena associated with the ROS (the transformed problem) are revealed and illustrated in time-domain and phase-space trajectories.

scholarly journals Results From The Amery Ice Shelf Project

1982 ◽  
Vol 3 ◽  
pp. 36-41 ◽  
Author(s):  
W. F. Budd ◽  
M. J. Corry ◽  
T. H. Jacka
Keyword(s):  
High Strain ◽  
Ice Core ◽  
Snow Accumulation ◽  
Ice Thickness ◽  
Surface Slope ◽  
Ice Shelf ◽  
Substantial Growth ◽  
Basal Ice ◽  
Amery Ice Shelf ◽  
Comprehensive Study

The major results from a comprehensive study of the Amery Ice Shelf are presented, following the work of a wintering expedition in 1968 and supplemented by further measurements during the summer seasons of 1969 to 1971. The Programme included ice-core drilling, oversnow surveys for ice movement and optical levelling, ice-thickness sounding, and measurements of snow accumulation. The new data obtained provide the basis for a more accurate assessment of the mass balance and dynamics of the ice shelf than was possible from the earlier surveys.The results indicate a substantial growth of basal ice under the ice shelf inland where the ice thickness is greater than 450 m. Further towards the ice front the high strain thinning is approximately balanced by the horizontal ice advection.The velocity distribution over the ice shelf is primarily governed by a substantial surface slope towards the ice front and high restraining shear stress along the sides.

Surface strong motion associated with a stick-slip event in a foam rubber model of earthquakes

1975 ◽  
Vol 65 (5) ◽  
pp. 1059-1071
Author(s):  
Ralph J. Archuleta ◽  
James N. Brune
Keyword(s):  
Strong Motion ◽  
Laboratory Model ◽  
Transverse Displacement ◽  
Stick Slip ◽  
Shear Wave Speed ◽  
Foam Rubber ◽  
Numerical Predictions ◽  
Rubber Model ◽  
Slip Event ◽  
Parkfield Earthquake

Abstract In this paper, we present and interpret dynamic displacement data for a stick-slip event in a foam rubber model of earthquake faulting. Static displacement data are used to infer the stress drop of about 0.016 μ, where μ is the shear modulus. The rupture velocity 0.7 β, where β is the shear-wave speed, is also inferred from the data. The observed particle displacement and particle velocity data are compared with analytical and numerical predictions. Doppler focusing of energy by rupture propagation is clearly observed. No large transverse displacement pulse such as that observed at Station 2 of the Parkfield earthquake is observed. In addition to its value for testing analytical and numerical predictions, the laboratory model provides much needed information on the distribution of strong ground motion in the neighborhood of a fault and thus helps in the problem of microzonation for earthquakes.

Excitation of San Andreas tremors by thermal instabilities below the seismogenic zone

2020 ◽  
Author(s):  
Lifeng Wang ◽  
Sylvain Barbot
Keyword(s):  
Frictional Resistance ◽  
Seismogenic Zone ◽  
Slow Slip ◽  
Stick Slip ◽  
Tectonic Plates ◽  
San Andreas ◽  
Wide Range ◽  
Shear Heating ◽  
Increasing Temperature ◽  
Host Rocks

<p>The relative motion of tectonic plates is accommodated at boundary faults through slow and fast ruptures that encompass a wide range of source properties. Near the Parkfield segment of the San Andreas fault, deep tremors and slow slip take place deeper than most seismicity, at temperature conditions typically associated with stable sliding, which should inhibit stick slip. However, laboratory experiments indicate that the strength of granitic gouge decreases with increasing temperature above 350$^\circ$C, providing a possible mechanism for weakening if temperature is to vary dynamically. Here, we argue that recurring tremor and slip at these depths may arise due to shear heating and the temperature dependence of frictional resistance and contact healing. Assuming a lower thermal diffusivity in the fault zone than in the surrounding rocks, numerical simulations can explain the recurrence pattern of the mid-crustal tremors and their correlative slip distribution, predicting peak temperatures exceeding the solidus of wet granite during sliding. We conclude that shear heating associated with slow slip can be sufficient to generate pseudotachylyte injection veins in host rocks even when fault slip is domin.</p>

Dynamic Instabilities in the Sliding of Two Layered Elastic Half-Spaces

1998 ◽  
Vol 120 (2) ◽  
pp. 289-295 ◽  
Author(s):  
G. G. Adams
Keyword(s):  
Steady State ◽  
Steady State Solution ◽  
Positive Real ◽  
Stick Slip ◽  
Dynamic Stresses ◽  
Dynamic Motion ◽  
Sliding Motion ◽  
Complex Eigenvalues ◽  
Wide Range ◽  
Loss Of Contact

Two flat layered elastic half-spaces, of different material properties, are pressed together and slide against each other with a constant coefficient of friction. Although a nominally steady-state solution exists, an analysis of the dynamic motion yields complex eigenvalues with positive real parts, i.e., a flutter instability. These results demonstrate that self-excited (unstable) motion occurs for a wide range of material combinations. The physical mechanism responsible for this instability is that of slip-wave destabilization. The influence of the properties of the layers on the destabilization of sliding motion is investigated. These dynamic instabilities lead either to regions of stick-slip or to areas of loss-of-contact. Finally the dynamic stresses at the interfaces between the layers and the semi-infinite bodies are determined and compared to the nominally steady-state stresses. These dynamic stresses are expected to play an important role in delamination.

scholarly journals Loading rates in California inferred from aftershocks

2008 ◽  
Vol 15 (2) ◽  
pp. 245-263 ◽  
Author(s):  
C. Narteau ◽  
P. Shebalin ◽  
M. Holschneider
Keyword(s):  
Decay Rate ◽  
Power Law ◽  
Slip Rate ◽  
Rate Of Change ◽  
Static Fatigue ◽  
Stick Slip ◽  
Temporal Properties ◽  
Seismological Data ◽  
Slip Event ◽  
Aftershock Decay Rate

Abstract. We estimate the loading rate in southern California and the change in stress induced by a transient slip event across the San Andreas fault (SAF) system in central California, using a model of static fatigue. We analyze temporal properties of aftershocks in order to determine the time delay before the onset of the power law aftershock decay rate. In creep-slip and stick-slip zones, we show that the rate of change of this delay is related to seismic and aseismic deformation across the SAF system. Furthermore, we show that this rate of change is proportional to the deficit of slip rate along the SAF. This new relationship between geodetic and seismological data is in good agreement with predictions from a Limited Power Law model in which the evolution of the duration of a linear aftershock decay rate over short time results from variations in the load of the brittle upper crust.

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