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1

Leakage-flow-induced vibration of a tube-in-tube slip joint  

SciTech Connect

The susceptibility of a cantilevered tube conveying water to self-excitation by leakage flow through a slip joint is assessed experimentally. The slip joint is formed by inserting a smaller, rigid tube into the free end of the cantilevered tube. Variations of the slip joint annular gaps and engagement lengths are tested, and several mechanisms for self-excitation are described.

Mulcahy, T.M.

1984-01-01

2

Leakage-flow-induced vibration of a tube-in-tube slip joint. [LMFBR  

SciTech Connect

The susceptibility of a cantilevered tube conveying water to self-excitation by leakage flow through a slip joint is assessed experimentally. The slip joint is formed by inserting a smaller, rigid tube into the free end of the cantilevered tube. Variations of the slip joint annular gaps and engagement lengths are tested, and several mechanisms for self-excitation are described.

Mulcahy, T.M.

1983-06-01

3

Stick-slip friction and wear of articular joints.  

PubMed

Stick-slip friction was observed in articular cartilage under certain loading and sliding conditions and systematically studied. Using the Surface Forces Apparatus, we show that stick-slip friction can induce permanent morphological changes (a change in the roughness indicative of wear/damage) in cartilage surfaces, even under mild loading and sliding conditions. The different load and speed regimes can be represented by friction maps--separating regimes of smooth and stick-slip sliding; damage generally occurs within the stick-slip regimes. Prolonged exposure of cartilage surfaces to stick-slip sliding resulted in a significant increase of surface roughness, indicative of severe morphological changes of the cartilage superficial zone. To further investigate the factors that are conducive to stick-slip and wear, we selectively digested essential components of cartilage: type II collagen, hyaluronic acid (HA), and glycosaminoglycans (GAGs). Compared with the normal cartilage, HA and GAG digestions modified the stick-slip behavior and increased surface roughness (wear) during sliding, whereas collagen digestion decreased the surface roughness. Importantly, friction forces increased up to 2, 10, and 5 times after HA, GAGs, and collagen digestion, respectively. Also, each digestion altered the friction map in different ways. Our results show that (i) wear is not directly related to the friction coefficient but (ii) more directly related to stick-slip sliding, even when present at small amplitudes, and that (iii) the different molecular components of joints work synergistically to prevent wear. Our results also suggest potential noninvasive diagnostic tools for sensing stick-slip in joints. PMID:23359687

Lee, Dong Woog; Banquy, Xavier; Israelachvili, Jacob N

2013-02-12

4

EPOXIDATION OF SMALL ORGANIC MOLECULES USING A SPINNING TUBE-IN-TUBE REACTOR  

EPA Science Inventory

The commodity-scale epoxidation of several organic molecules has been carried out using a Spinning Tube-in-Tube (STTr) reactor (manufactured by Kreido Laboratories). This reactor, which embodies and facilitates the use of Green Chemistry principles and Process Intensification, a...

5

PROGRESS IN PROCESS INTENSIFICATION: SYNTHESIS OF IMINES USING A SPINNING TUBE-IN-TUBE REACTOR  

EPA Science Inventory

The high purity, high throughput synthesis of a number of imines (Schiff bases) using a spinning tube-in-tube reactor (STT, Kreido Laboratories, Camarillo, CA) has been carried out. The STT reactor allows the high throughput production of high purity imines from a wide variety of...

6

Coseismic slip model of the 2008 Wenchuan earthquake derived from joint inversion of interferometric synthetic aperture  

E-print Network

Click Here for Full Article Coseismic slip model of the 2008 Wenchuan earthquake derived from joint; published 28 April 2010. [1] We derived a coseismic slip model for the Mw 7.9 2008 Wenchuan earthquake primarily distributed below the section of the fault that ruptured coseismically. Citation: Tong, X., D. T

Fialko, Yuri

7

COMMODITY SCALE SYNTHESIS OF 1-METHYLIMIDAZOLE BASED IONIC LIQUIDS USING A SPINNING TUBE-IN-TUBE REACTOR  

EPA Science Inventory

The continuous large-scale preparation of several 1-methylimidazole based ionic liquids was carried out using a Spinning Tube-in-Tube (STT) reactor (manufactured by Kreido Laboratories). This reactor, which embodies and facilitates the use of Green Chemistry principles and Proce...

8

IN-SITU MONITORING OF PRODUCT STREAMS FROM A SPINNING TUBE-IN-TUBE REACTOR USING A METTLER-TOLEDO REACT-IR  

EPA Science Inventory

A Mettler-Toledo ReactIR system has been used for in-line, real-time monitoring of the product stream from a spinning tube-in-tube reactor (STT®, Kreido Laboratories, Camarillo California). This combination of a process intensified continuous-flow reactor and an in-situ analytic...

9

The effect of yield strength mis-match on the fracture analysis of welded joints: slip-line field solutions for pure bending  

Microsoft Academic Search

Plane strain and plane stress slip-line solutions for single notched bending specimens with a central mismatched welded joint have been derived. The crack has been located on the fusion line (interface) and at the middle of the weld metal. 2D and 3D finite element analysis has been performed to verify the theoretical results and to investigate the effect of specimen

S. Hao; K.-H. Schwalbe; A. Cornec

2000-01-01

10

Coseismic Fault Slip Rupture from the Joint Inversion of Teleseismic, Local Strong-Motion and CGPS Related to the 2010 Jia-Shian Earthquake in Southwestern Taiwan  

NASA Astrophysics Data System (ADS)

The Jia-Shian earthquake (Mw=6.3) occurred on 04th March 2010 in the southwestern Taiwan. We used the waveforms of teleseismics to identify the strike, dip and rake of focal mechanism are 311/33/37. Furthermore, we explored the strike, dip and rake are 316/40/44 on the first pulse of the teleseismic P wave. We also took account of the Continuous Global Positioning System (CGPS) data for the coseismic offset. The maximum horizontal and vertical (uplift) of coseismic offsets at the surface are 29.8mm± 1.0mm and 30.6mm± 5.1mm, respectively at station GS51. Moreover, the space and time distribution of slip during the coseismic rupture was modeled by the joint inversion, which includes the CGPS coseismic offset, the teleseismic, and near field seismic records. We identified the faults geometry and reconstructed the rupture process of coseismic faults slip. The initial rupture was generated on the northwest - southeast trending fault and propagated to the northeast - southwest trending structure after 5 s of main shock. Their strike, dip and rake are 311/33/37 and 020/25/108, respectively. The average slip of rupture was 20.1 cm, with the maximum slip of 50.4 cm. The rupture of the seismic moment was 4.0 × 10 ^ 25 dyne-cm in 30 s of duration time.The slip rupture constrained the synthetic data quite well, especially for the CGPS coseismic offset. We inferred the Jia-Shian earthquake took place on blind fault and the northeast - southwest trending structure was activated following the rupture on main northwest - southeast trending fault.

Lin, Kuan-Chuan; Delouis, Bertrand; Hu, Jyr-Ching; Nocquet, Jean-Mathieu; Mozziconacci, Laetitia; Bethoux, Nicole

2013-04-01

11

Depth distribution of coseismic slip along the Nankai Trough, Japan, from joint inversion of geodetic and tsunami data  

Microsoft Academic Search

Two large earthquakes, the 1944 Tonankai earthquake and the 1946 Nankaido earthquake, occurred on the Nankai trough, where the Philippine Sea plate is subducting beneath the Eurasian plate. Coseismic crustal movements on land were measured by leveling, while those in ocean were recorded as tsunami waveforms on tide gauges. The coseismic slip distribution inverted from these data shows that the

Kenji Satake

1993-01-01

12

Horizontal slip along Alleghanian joints of the Appalachian plateau: evidence showing that mild penetrative strain does little to  

E-print Network

suggests that parent cracks in shale of the plateau were subject to a shear stress of ,1 MPa (Younes in black shales of the Geneseo and Middlesex Formations of the Catskill Delta complex, Finger Lakes plateau comes from fringe cracks that develop when early parent joints are subjected to a later bedding

Engelder, Terry

13

A joint inversion of focal mechanisms and GPS displacements for absolute crustal stress and coseismic fault slip using data from the 1999 Chi-Chi, Taiwan, earthquake  

Microsoft Academic Search

Inversion of coseismic surface displacements has become a standard tool for estimating fault geometry and coseismic slip distribution on the seismogenic fault plane. Recently, Sun et al. (paper in review) have developed a method for inverting for fault geometry and slip from coseismic surface displacements assuming a uniform stress drop on a fault in an elastic half space. In reality,

Y. Yang; K. M. Johnson; R. Y. Chuang

2010-01-01

14

Partitioning Slip  

NSDL National Science Digital Library

This activity consists of four exercises that deal with the partitioning of slip within scenarios involving two or more faults. The first three are hypothetical situations; the last activity focuses on the plate boundary in southern California.

15

The 2011 Mw9.0 Tohoku-Oki Earthquake: Joint occurrence of tectonic stress-driven and lithostatic stress-driven slips along the plate boundary  

NASA Astrophysics Data System (ADS)

The across-arc rupture process of the Tohoku-Oki Earthquake through its hypocenter has following characteristics. (1)Both the inner and outer wedges were ruptured. Slip in the outer wedge (˜40 m) was significantly greater than slip in the inner wedge (˜20 m) (Lay et al., 2011). (2)Rupture occurred initially in the inner wedge and then extended into the outer wedge all the way along the plate boundary to its updip end (Ide et al., 2011; Fujiwara et al., 2011). (3)A number of aftershocks include normal faulting in the inner and outer wedges and return slips in the inner wedge (Asano et al., 2011; Ide et al., 2011). Recent across-arc seismic surveys have revealed the following: (A)The boundary between the seismically active inner and inactive outer wedges is structurally well-defined as the plate bending point, across which the dip of plate interface changes sharply (Ito et al., 2005; Fujie et al., 2006). (B)The outer wedge at relatively shallow depths is dominated by normal faults except near its updip toe, suggesting that the outer wedge is not horizontally compressed over a time scale of the earthquake cycle (Nakamura et al., 2011). We develop a simple spring-block model of the earthquake cycle consistent with all of the above features, supported partially by the elastic taper theory of outer wedge (Hu and Wang, 2006). In our model, slip along the plate boundary cannot easily climb over its bending point around which slip direction changes by about 10 degree. While slip occurs repeatedly in the inner wedge, the outer wedge remains contacted with the underlying plate even if basal friction is low enough to support only the outer wedge in an extensionally critical state (Wang and Hu, 2006). In fact, dominance of normal faults in the outer ridge seems to favor its relatively low basal friction. Repeated slips in the inner wedge and little slip in the outer wedge accumulate stress near the plate bending point. The accumulated stress is eventually released by slip originated in the inner wedge but extending into the outer wedge well across their boundary with a much larger amount of slip in the outer wedge where strain energy has been poorly accumulated at the preseismic stage. Coseismic reduction of the basal friction changes the lithostatic stress system in the outer wedge and causes additional slip accordingly. If the basal friction drops to zero, the lithostatic stress-driven slip brings the inner and outer wedges in a state of horizontal tension on the order of a few tens MPa. With such a complete stress drop assumption (Hasegawa et al., 2011; Nettles et al., 2011) and with model repeating times of once/50yrs and once/500yrs for major and giant earthquakes at a subduction rate of 8 cm/yr, our model predicts inner and outer wedge slips of 2 m and 0 m for a major earthquake, and (20+?) m and (40+2?) m for a giant earthquake like the 2011 Tohoku-Oki Earthquake, where ? and 2? are excess slips of lithostatic stress origin in the inner and outer wedges, which may be estimated by the elastic taper theory if the initial basal friction in the outer wedge is specified. The resultant horizontal tension is relaxed by normal faulting within the inner and outer wedges and return slip along the inner wedge plate boundary.

Fukao, Y.; Hori, T.; Kodaira, S.

2011-12-01

16

Kinematic Slip Model for 12 May 2008 Wenchuan-Beichuan Mw 7.9 Earthquake from Joint Inversion of ALOS, Envisat, and Teleseismic Data  

NASA Technical Reports Server (NTRS)

The presentations explores kinematics of the Wenchaun-Beichuan earthquake using data from ALOS, Envisat, and teleseismic recordings. Topics include geomorphic mapping, ALOS PALSAR range offsets, ALOS PALSAR interferometry, Envisat IM interferometry, Envisat ScanSAR, Joint GPS-InSAR inversion, and joint GPS-teleseismic inversion (static and kinematic).

Fielding, Eric; Sladen, Anthony; Avouac, Jean-Philippe; Li, Zhenhong; Ryder, Isabelle; Burgmann, Roland

2008-01-01

17

Kinematic fault slip model from joint inversion of teleseismic, GPS, InSAR and subpixel-correlation measurements of the 2010 El Mayor-Cucapah earthquake and postseismic deformation (Invited)  

NASA Astrophysics Data System (ADS)

We use interferometric analysis of synthetic aperture radar (SAR) images (InSAR) and pixel tracking by subpixel correlation of SAR and optical images to map the fault ruptures and surface deformation of the 4 April 2010 El Mayor-Cucapah earthquake (Mw 7.2) in Baja California, Mexico. We then combine sampled InSAR and subpixel correlation results with GPS offsets at PBO stations and teleseismic waveforms in a joint inversion to produce a kinematic fault slip model. Pixel-tracking measurements from SPOT 2.5 m panchromatic images and from Envisat ASAR and ALOS PALSAR images measure large ground displacements close to fault ruptures, with a strong discontinuity where the rupture reached the surface. Optical image subpixel correlation measures horizontal displacements in both the east-west and north-south directions and shows the earthquake ruptured the Pescadores Fault in the southern Sierra Cucapah and the Borrego Fault in the central and northern edge of the mountain range. At the south end of the Sierra Cucapah, the fault ruptures fork into two subparallel strands with substantial slip on both visible. SAR image subpixel correlation measures horizontal deformation in the along-track direction of the satellite (approximately north or south) and in the radar line-of-sight direction. SAR along-track offsets, especially on ALOS images, show that there is a large amount of right-lateral slip (1-3 m) on a previously unmapped system of faults extending about 60 km to the southeast of the epicenter beneath the Colorado River Delta named the Indiviso Fault system. Aftershocks also extend approximately the same distance to the southeast. InSAR analyses of Envisat, ALOS and UAVSAR images, measure the surface displacements in the same radar line-of-sight as the range pixel tracking, but with much greater precision. Combination of SAR images from different directions allows the separation of the vertical and east components of the deformation, revealing the large normal fault slip in the Sierra Cucapah (down to the east) and blocks with substantial vertical motion in the Delta (both down to the east and down to the west). Kinematic finite fault modeling shows a bilateral rupture with fault slip shallower than 10 km on the faults to the NW and SE of the epicenter. The InSAR also reveals slip on many minor faults on both sides of the Sierra Cucapah and to the northwest, with displacements of cm to 10’s of cm. High-resolution UAVSAR coseismic and postseismic interferograms revealed triggered slip on a number of faults in the Yuha desert and Salton Trough, with some slip occurring in the three months after the main shock. Postseismic InSAR shows rapid afterslip on shallow faults at the north and south ends of the main coseismic rupture. Areas of the Colorado River Delta that subsided during the main earthquake continued to subside afterwards. Larger spatial scales of postseismic deformation that would be expected from viscoelastic relaxation are difficult to measure in the InSAR data because of large variations in tropospheric water vapor.

Fielding, E. J.; Wei, S.; Leprince, S.; Sladen, A.; Simons, M.; Avouac, J.; Briggs, R. W.; Hudnut, K. W.; Helmberger, D. V.; Hensley, S.; Hauksson, E.; Gonzalez-Garcia, J. J.; Herring, T.; Akciz, S. O.

2010-12-01

18

The role of pressure solution seam and joint assemblages in the formation of strike-slip and thrust faults in a compressive tectonic setting; The Variscan of south-western Ireland  

NASA Astrophysics Data System (ADS)

The Ross Sandstone in County Clare, Ireland, was deformed by an approximately north-south compression during the end-Carboniferous Variscan orogeny. The initial assemblage consists of mutually abutting orthogonal arrays of 170° oriented set 1 joints/veins (JVs) and approximately 75° oriented set 1 pressure solution seams (PSSs) formed under the same stress conditions. Orientations of splay JVs and PSSs (set 2) suggest a clockwise remote stress rotation of about 35° responsible for the contemporaneous shearing of the set 1 arrays. Among these nearly orthogonal strike-slip faults, the prominent set is sub-parallel to set 1 JVs. These faults are formed by the linkage of en-echelon segments with broad damage zones responsible for right-lateral offsets of hundreds of meters. Thrust faults with up to 30 m of offset initiate within shale horizons and follow either the PSSs in the sandstones or high-angle shales within tilted sequences. Within the large thrust fault zones, compartmentalised blocks of rocks are bounded by thrust faults segments with various dip angles. Strike-slip and thrust faults are contemporaneous and owe their existence to initial weaknesses in the form of JVs and PSSs rather than by switching relative stress magnitudes and orientations associated with Andersonian models of faults and related stress orientations.

Nenna, Filippo; Aydin, Atilla

2011-11-01

19

Tube-in-tube thermophotovoltaic generator  

DOEpatents

A thermophotovoltaic device includes at least one thermal radiator tube, a cooling tube concentrically disposed within each thermal radiator tube and an array of thermophotovoltaic cells disposed on the exterior surface of the cooling tube. A shell having a first end and a second end surrounds the thermal radiator tube. Inner and outer tubesheets, each having an aperture corresponding to each cooling tube, are located at each end of the shell. The thermal radiator tube extends within the shell between the inner tubesheets. The cooling tube extends within the shell through the corresponding apertures of the two inner tubesheets to the corresponding apertures of the two outer tubesheets. A plurality of the thermal radiator tubes can be arranged in a staggered or an in-line configuration within the shell.

Ashcroft, John (Scotia, NY); Campbell, Brian (Scotia, NY); DePoy, David (Clifton Park, NY)

1998-01-01

20

Tube-in-tube thermophotovoltaic generator  

DOEpatents

A thermophotovoltaic device includes at least one thermal radiator tube, a cooling tube concentrically disposed within each thermal radiator tube and an array of thermophotovoltaic cells disposed on the exterior surface of the cooling tube. A shell having a first end and a second end surrounds the thermal radiator tube. Inner and outer tubesheets, each having an aperture corresponding to each cooling tube, are located at each end of the shell. The thermal radiator tube extends within the shell between the inner tubesheets. The cooling tube extends within the shell through the corresponding apertures of the two inner tubesheets to the corresponding apertures of the two outer tubesheets. A plurality of the thermal radiator tubes can be arranged in a staggered or an in-line configuration within the shell. 8 figs.

Ashcroft, J.; Campbell, B.; DePoy, D.

1998-06-30

21

Journal of Biomechanics 34 (2001) 14391445 Lower extremity corrective reactions to slip events  

E-print Network

Journal of Biomechanics 34 (2001) 1439­1445 Lower extremity corrective reactions to slip events in the workplace is attributed to slips and falls. Biomechanical responses to actual slip events determine whether rights reserved. Keywords: Slips biomechanics; Gait biomechanics; Corrective reactions; Joint moments 1

22

Memory Slips and Dementia  

MedlinePLUS

... the lower right-hand corner of the player. Memory Slips and Dementia HealthDay September 26, 2014 Related MedlinePlus Pages Dementia Memory Seniors' Health Transcript Little memory slips as you ...

23

Stress coupling tested in fault slip inversion  

NASA Astrophysics Data System (ADS)

The seismic cycle includes the interseismic, coseismic and postseismic phase. The large earthquakes release the interseismically accumulated stress on the fault, and are followed by stress relaxation processes in the postseismic phase. Based on the geodetic measurements, the stress coupling in the seismic cycle can be investigated by interseismic slip deficit, coseismic rupture and postseismic slip distributions. However, it is well-known that the fault slip inversions based only on the measurements on the surface are typically non-unique and subject to large uncertainties. In this study, we firstly assume the existence of stress coupling in the seismic cycle, and then do the stress constrained joint inversion in Bayesian approach (Wang et al., 2012) to invert either for (1) interseismic slip deficit and coseismic slip or for (2) coseismic slip and postseismic creep. Based on the modeling results, we evaluate if the assumed stress coupling is reasonable and if the stress coupling is able to be reflected from the available geodetic measurements. We take the earthquakes in the regions with well-instrumented network (such as the 2004 M6.0 Parkfield earthquake, the 2010 M8.7 earthquake and the 2011 M9.1 Tohoku-Oki earthquake) as study cases.

Wang, L.; Hainzl, S.; Zoeller, G.

2013-12-01

24

SlipKnot Home Page  

NSDL National Science Digital Library

SlipKnot (w/o SLIP) MicroMind, New York, NY, US SlipKnot is a graphical World Wide Web browser specifically designed for Microsoft Windows users who have UNIX shell accounts with their service providers. Its primary feature is that it does not require SLIP or PPP or TCP/IP services. SlipKnot is distributed as restricted shareware, with a registration fee.

25

Episodic silence and slip (Invited)  

NASA Astrophysics Data System (ADS)

Conditions in the transition zone between seismogenic and stable slip produce hybrid events where slip occurs as slow earthquakes. In Cascadia, these slow earthquakes are consistently observed as slow interface-slip accompanied by persistent tectonic tremor. However, not all slow slip at other plate boundaries coincides with observed tremor, leaving the physics of tremor generation and the connection between tremor and slow slip poorly understood. Here we analyze seismic, geodetic and borehole strainmeter data to observe a large, tremor-generating slow earthquake temporarily fall silent in the middle of its along-strike rupture. This gap, where low slip-rate slip continues without tremor, occurs on a portion of the fault that has repeatedly produced tremor in past events and later generates tremor as higher slip-rate slip back-propagates into it. The finding suggests that, depending on the slip rate, the same episode can change from tremorgenic, to silent and back again, and the same section of fault can slip both with and without tremor. This result emphasizes slip speed and/or current stress state over fault rheology as a controlling factor, providing an important clue for understanding the physics of tremor generation and the relationship between tremor and slip. The result also underscores the potential role of aseismic slip in accommodating plate motion and the limitations of using tremor as a proxy for slip.

Wech, A.; Bartlow, N. M.

2013-12-01

26

Slip Rates on young faults  

NSDL National Science Digital Library

Students use measured ages and offset of quaternary surfaces to determine vertical slip rates of a young fault. Students then must determine if vertical slip rates have varied significantly through time.

Huerta, Audrey

27

Molecular mechanisms of liquid slip  

Microsoft Academic Search

It is now well-established that the liquid adjacent to a solid need not be stationary - it can slip. How this slip occurs is unclear. We present molecular-dynamics (MD) simulation data and results from an analytical model which support two mechanisms of slip. At low levels of forcing, the potential field generated by the solid creates a ground state which

A. Martini; A. Roxin; R. Q. Snurr; Q. Wang; S. Lichter

2008-01-01

28

The frictional properties of joints in rock  

Microsoft Academic Search

Summary The conditions for sliding over artificial joint surfaces have been studied experimentally by cutting rock cylinders at various angles to their axes and studying slip over these surfaces in a triaxial testing apparatus. The types of joint used were: (i) filled with plaster to simulate a soft joint filling, (ii) bare surfaces ground approximately flat, and (iii) natural surfaces

J. C. Jaeger

1959-01-01

29

Distribution of slip from 11 Mw > 6 earthquakes in the northern Chile subduction zone  

E-print Network

Distribution of slip from 11 Mw > 6 earthquakes in the northern Chile subduction zone M. E to constrain the relative location of coseismic slip from 11 earthquakes on the subduction interface both jointly and separately for the four largest earthquakes during this time period (1993 Mw 6.8; 1995

Simons, Mark

30

Nucleation and growth of strike slip faults in granite.  

USGS Publications Warehouse

Fractures within granodiorite of the central Sierra Nevada, California, were studied to elucidate the mechanics of faulting in crystalline rocks, with emphasis on the nucleation of new fault surfaces and their subsequent propagation and growth. Within the study area the fractures form a single, subparallel array which strikes N50o-70oE and dips steeply to the S. Some of these fractures are identified as joints because displacements across the fracture surfaces exhibit dilation but no slip. The joints are filled with undeformed minerals, including epidote and chlorite. Other fractures are identified as small faults because they display left-lateral strike slip separations of up to 2m. Slickensides, developed on fault surfaces, plunge 0o-20o to the E. The faults occur parallel to, and in the same outcrop with, the joints. The faults are filled with epidote, chlorite, and quartz, which exhibit textural evidence of shear deformation. These observations indicate that the strike slip faults nucleated on earlier formed, mineral filled joints. Secondary, dilational fractures propagated from near the ends of some small faults contemporaneously with the left-lateral slip on the faults. These fractures trend 25o+ or -10o from the fault planes, parallel to the direction of inferred local maximum compressive stress. The faults did not propagate into intact rock in their own planes as shear fractures. -from Authors

Segall, P.; Pollard, D.P.

1983-01-01

31

Low-Friction Joint for Robot Fingers  

NASA Technical Reports Server (NTRS)

Mechanical linkage allows adjacent parts to move relative to each other with low friction and with no chatter, slipping, or backlash. Low-friction joint of two surfaces in rolling contact, held in alinement by taut flexible bands. No sliding friction or "stick-slip" motion: Only rolling-contact and bending friction within bands. Proposed linkage intended for finger joints in mechanical hands for robots and manipulators.

Ruoff, C. F.

1985-01-01

32

Slip partitioning by elastoplastic propagation of oblique slip at depth.  

PubMed

Oblique motion along tectonic boundaries is commonly partitioned into slip on faults with different senses of motion. The origin of slip partitioning is important to structural geology, tectonophysics, and earthquake mechanics. Partitioning can be explained by the upward elastoplastic propagation of oblique slip from a fault or shear zone at depth. The strain field ahead of the propagating fault separates into zones of predominantly normal, reverse, and strike-slip faulting. The model successfully predicts the distribution of fault types along parts of the San Andreas and Haiyuan faults. PMID:12750513

Bowman, David; King, Geoffrey; Tapponnier, Paul

2003-05-16

33

Formation and Suppression of Strike-Slip Fault Systems  

NASA Astrophysics Data System (ADS)

Strike-slip faults are a defining feature of plate tectonics, yet many aspects of their development and evolution remain unresolved. For intact materials and/or regions, a standard sequence of shear development is predicted from physical models and field studies, commencing with the formation of Riedel shears and culminating with the development of a throughgoing fault. However, for materials and/or regions that contain crustal heterogeneities (normal and/or thrust faults, joints, etc.) that predate shear deformation, kinematic evolution of strike-slip faulting is poorly constrained. We present a new plane-stress finite-strain physical analog model developed to investigate primary deformation zone evolution in simple shear, pure strike-slip fault systems in which faults or joints are present before shear initiation. Experimental results suggest that preexisting mechanical discontinuities (faults and/or joints) have a marked effect on the geometry of such systems, causing deflection, lateral distribution, and suppression of shears. A lower limit is placed on shear offset necessary to produce a throughgoing fault in systems containing preexisting structures. Fault zone development observed in these experiments provides new insight for kinematic interpretation of structural data from strike-slip fault zones on Earth, Venus, and other terrestrial bodies.

Curren, Ivy S.; Bird, Peter

2014-03-01

34

Mechanism of slip and twinning  

NASA Technical Reports Server (NTRS)

The objectives are to: (1) demonstrate the mechanisms of deformation in body centered cubic (BCC), face centered cubic (FCC), and hexagonal close-packed (HCP)-structure metals and alloys and in some ceramics as well; (2) examine the deformed microstructures (slip lines and twin boundaries) in different grains of metallic and ceramic specimens; and (3) study visually the deformed macrostructure (slip and twin bands) of metals and alloys. Some of the topics covered include: deformation behavior of materials, mechanisms of plastic deformation, slip bands, twin bands, ductile failure, intergranular fracture, shear failure, slip planes, crystal deformation, and dislocations in ceramics.

Rastani, Mansur

1992-01-01

35

Coherent quantum phase slip.  

PubMed

A hundred years after the discovery of superconductivity, one fundamental prediction of the theory, coherent quantum phase slip (CQPS), has not been observed. CQPS is a phenomenon exactly dual to the Josephson effect; whereas the latter is a coherent transfer of charges between superconducting leads, the former is a coherent transfer of vortices or fluxes across a superconducting wire. In contrast to previously reported observations of incoherent phase slip, CQPS has been only a subject of theoretical study. Its experimental demonstration is made difficult by quasiparticle dissipation due to gapless excitations in nanowires or in vortex cores. This difficulty might be overcome by using certain strongly disordered superconductors near the superconductor-insulator transition. Here we report direct observation of CQPS in a narrow segment of a superconducting loop made of strongly disordered indium oxide; the effect is made manifest through the superposition of quantum states with different numbers of flux quanta. As with the Josephson effect, our observation should lead to new applications in superconducting electronics and quantum metrology. PMID:22517162

Astafiev, O V; Ioffe, L B; Kafanov, S; Pashkin, Yu A; Arutyunov, K Yu; Shahar, D; Cohen, O; Tsai, J S

2012-04-19

36

{110} Slip with {112} slip traces in bcc Tungsten  

PubMed Central

While propagation of dislocations in body centered cubic metals at low temperature is understood in terms of elementary steps on {110} planes, slip traces correspond often with other crystallographic or non-crystallographic planes. In the past, characterization of slip was limited to post-mortem electron microscopy and slip trace analysis on the sample surface. Here with in-situ Laue diffraction experiments during micro-compression we demonstrate that when two {110} planes containing the same slip direction experience the same resolved shear stress, sharp slip traces are observed on a {112} plane. When however the {110} planes are slightly differently stressed, macroscopic strain is measured on the individual planes and collective cross-slip is used to fulfill mechanical boundary conditions, resulting in a zig-zag or broad slip trace on the sample surface. We anticipate that such dynamics can occur in polycrystalline metals due to local inhomogeneous stress distributions and can cause unusual slip transfer among grains. PMID:23989456

Marichal, Cecile; Van Swygenhoven, Helena; Van Petegem, Steven; Borca, Camelia

2013-01-01

37

Suppression of strike-slip fault systems  

NASA Astrophysics Data System (ADS)

In orogens elongated parallel to a great circle about the Euler pole for the two bounding plates, theory requires simple-shear deformation in the form of distributed deformation or velocity discontinuities across strike-slip faults. This type of deformation, however, does not develop at all plate boundaries requiring toroidal motion. Using the global plate boundary model, PB2002 [Bird, 2003], as the basis for identifying areas where expected simple-shear deformation is absent or underdeveloped, it was also possible to identify two potential causes for this behavior: (1) the presence of extensive fracturing at right angles to the shear plane and (2) regional cover of flood basalts or andesites with columnar joints. To test this hypothesis, a new plane-stress finite-strain model was developed to study the effects of such pre-existing structures on the development of simple shear in a clay cake. A homogenous kaolinite-water mixture was poured into a deforming parallelogram box and partially dried to allow for brittle and plastic deformation at and below the surface of the clay, respectively. This was floated on a dense fluid foundation, effectively removing basal friction, and driven by a motor in a sinistral direction from the sides of the box. Control experiments produced classic Riedel model fault assemblages and discrete, through-going primary deformation zones (PDZs); experiments with pre-existing structures developed the same, though subdued and distributed, fault assemblages but did not develop through-going PDZs. Although formation of strike-slip faults was underdeveloped at the surface in clay with pre-existing structures, offset within the clay cake (measured, with respect to a fixed point, by markers on the clay surface) as a fraction of total offset of the box was consistently larger than that of the control experiments. This suggests that while the extent of surface faulting was lessened in clay with pre-existing structures, slip was still occurring at depth. Selected areas on Earth with anomalously undeveloped strike-slip faulting where plate models would predict otherwise were compared with results from the analog model experiments in this study. Physical similarities between this model and Brothers Fault Zone (BFZ), Walker Lane (WL) and the South Iceland Seismic Zone (SISZ) imply that strike-slip faulting may be suppressed at the surface in these regions due to the presence of pre-existing structures. Filled circles show offset required for breakthrough faulting, empty circles denote lower limit of breakthrough. Triangles show clay offset as a fraction of box offset. Note that clays with pre-existing structures showed larger offsets although breakthrough did not occur.

Curren, I. S.

2012-12-01

38

Seismic slip of oceanic strike-slip earthquakes  

NASA Astrophysics Data System (ADS)

We investigate the controls on seismic slip in oceanic lithosphere through teleseismic body-wave modeling of oceanic strike-slip earthquakes to determine fault plane as well as the depth distribution of seismic rupture. At first-order we can combine modern constraints on oceanic transform faults of slip rate, cumulative seismic moment and improved centroid depths to reveal a disparity of strain release that must be accommodated with aseismic slip (Brune, 1968). We seek to attain a higher order of understanding the distribution and relationship between aseismic and seismically slipping areas of oceanic strike-slip faults. Examining the seismic slip of large earthquakes on these faults can help to constrain properties of oceanic lithosphere and determine if the thickness of the seismogenic zone is controlled by temperature, composition, geometry or a combination of attributes. Over 45 MW ? 7.0 oceanic strike-slip earthquakes have occurred since 1990, with 10 of these in the last two years alone, yet little is known about their depth, rupture pattern and fault orientation. The two largest earthquakes of 2012 occurred on April 11th and were both intraplate oceanic strike-slip earthquakes; they appear to have ruptured multiple orthogonally oriented faults with some rupture extending to unexpectedly great depths. The depth of oceanic strike-slip earthquakes is difficult to constrain, particularly in the shallow crust; this study uses teleseismic body-waves P and S as well as depth phases pP, sP and water multiples to enhance our precision. Earthquakes off the coast of Sumatra, California, Alaska and Western Australia as well as near the South Sandwich and Santa Cruz Islands are carefully repicked for phase arrivals and polarities. We calculate moment tensors for magnitude 6.0 ? MW ? 8.0 earthquakes in these areas with particular attention paid to the highly nodal first arriving P phase. For events of magnitude 7.0 ? MW ? 8.0 since 1990 we perform finite-fault slip inversions on the two conjugate planes to identify which faults ruptured during each event. These large earthquakes rupture a broad range of oceanic lithosphere aged 0 to 70 My and above (Müller et al, 2008) and occur in both interplate transform and intraplate tectonic settings. It is widely accepted that temperature has significant control on the depth extent of seismic rupture, but with an extensive sampling of oceanic strike-slip earthquakes we can determine if other lithospheric properties hold an observable role to further explain rupture complexity with depth and along strike.

Aderhold, K.; Abercrombie, R. E.; Antolik, M. S.

2013-12-01

39

A joint analysis of GPS motions and InSAR to infer the coseismic surface deformation of the Izmit, Turkey earthquake  

Microsoft Academic Search

From a joint analysis of GPS and InSAR data we have determined the kinematic coseismic surface deformation of the 1999 August 17, Izmit (Turkey) earthquake in terms of strain, rotation and fault slip. The fault slip contribution shows two distinct peaks: one of ~4 m of slip at Gölcük, and a second of ~2.9 m slip near Sapanca Lake. The

A. G. Bos; S. Usai; W. Spakman

2004-01-01

40

Packer slips for CRA completion  

SciTech Connect

This patent describes a slip anchor stud for use in combination with a well packer comprising a main body portion having a length dimension and a radius dimension, a plurality of ribs formed on the main body portion.

Lane, A.R.; Wheeler, R.B.; Jackson, A.T.

1992-07-21

41

Slipping and Rolling Wheel Model  

NSDL National Science Digital Library

The EJS Slipping and Rolling Wheel Model shows the motion of a wheel rolling on a floor subject to friction. The simulation allows the user to change the initial translational and rotational velocities of the wheel, v and ω, the mass, radius, and mass distribution, R, m, and C of the wheel. By controlling these variables, the dynamics of the wheel can be changed to show the sliding, then rolling without slipping, of the wheel. The Slipping and Rolling Wheel Model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_mech_newton_SlippingRollingWheel.jar file will run the program if Java is installed. The user can modify this simulation if EJS is installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item.

Christian, Wolfgang; Belloni, Mario

2009-02-26

42

Micro/macro-slip damping in beams with frictional contact interface  

NASA Astrophysics Data System (ADS)

Friction in contact interfaces of assembled structures is the prime source of nonlinearity and energy dissipation. Determination of the dissipated energy in an assembled structure requires accurate modeling of joint interfaces in stick, micro-slip and macro-slip states. The present paper proposes an analytical model to evaluate frictional energy loss in surface-to-surface contacts. The goal is to develop a continuous contact model capable of predicting the dynamics of friction interface and dissipation energy due to partial slips. To achieve this goal, the governing equations of a frictional contact interface are derived for two distinct contact states of stick and partial slip. A solution procedure to determine stick-slip transition under single-harmonic excitations is derived. The analytical model is verified using experimental vibration test responses performed on a free-frictionally supported beam under lateral loading. The theoretical and experimental responses are compared and the results show good agreements between the two sets of responses.

Asadi, K.; Ahmadian, H.; Jalali, H.

2012-10-01

43

Earthquake slip distribution estimation, using a random vector approach  

NASA Astrophysics Data System (ADS)

InSAR and/or GNSS data are routinely used to invert for the slip distribution on faults that rupture during earthquakes. Where exactly slip occurred has implications for future seismic hazard. However, in order to regularize the inversion, extra assumptions about the smoothness of the slip distribution are usually included, which do not have a physical basis. Here we propose a new approach for constraining the slip distribution based on a random vector model following a von Karman autocorrelation function. While this approach also has no physical basis, it does have empirical support from a stochastic analysis of seismic finite-source slip inversions (Mai and Beroza, 2002). We implement the random vector constraint in a Bayesian fashion and use a Markov chain Monte Carlo (MCMC) algorithm to derive the posterior joint probability distribution for each of the slipping patches. The von Karman function depends on two parameters: correlation length and Hurst number (related to fractal dimension). We use histograms from the stochastic analysis for these two parameters, which differ in along-strike and down-dip directions, to derive prior probability distributions, but allow them to vary during the inversion as hyperparameters. We also let the model parameters that control the fault geometry vary freely. In other inversion approaches these are usually fixed prior to inversion for distributed slip, due primarily to the difficulty in searching the resulting model space within a reasonable CPU time. To overcome this problem we have implemented a variation to the usual MCMC approach, in which the step size for each of the model parameters is regularly updated to optimize convergence time. We have applied our approach to a number of earthquakes and find that the results sometimes differ markedly to those incorporating the common Laplacian smoothing constraint. In addition, the fast run times mean that this approach could be routinely applied to data from the upcoming Sentinel-1 mission to automatically derive slip distributions for all earthquakes that cause significant surface displacement. References: Mai, P. M., and G. C. Beroza (2002), A spatial random field model to characterize complexity in earthquake slip, J. Geophys. Res., 107(B11), 2308.

Hooper, A. J.

2012-12-01

44

Velocity slip on curved surfaces  

NASA Astrophysics Data System (ADS)

The Navier boundary condition for velocity slip on flat surfaces, when expressed in tensor form, is readily extended to surfaces of any shape. We test this assertion using molecular dynamics simulations of flow in channels with flat and curved walls and for rotating cylinders and spheres, all for a wide range of solid-liquid interaction strengths. We find that the slip length as conventionally measured at a flat wall in Couette flow is the same as that for all other cases with curved and rotating boundaries, provided the atomic interactions are the same and boundary shape is properly taken into account. These results support the idea that the slip length is a material property, transferable between different flow configurations.

Chen, Weikang; Zhang, Rui; Koplik, Joel

2014-02-01

45

Velocity slip on curved surfaces  

E-print Network

The Navier boundary condition for velocity slip on flat surfaces, when expressed in tensor form, is readily extended to surfaces of any shape. We test this assertion using molecular dynamics simulations of flow in channels with flat and curved walls and for rotating cylinders and spheres, all for a wide range of solid-liquid interaction strengths. We find that the slip length as conventionally measured at a flat wall in Couette flow is the same as that for all other cases with curved and rotating boundaries, provided the atomic interactions are the same and boundary shape is properly taken into account. These results support the idea that the slip length is a material property, transferable between different flow configurations.

Weikang Chen; Rui Zhang; Joel Koplik

2013-09-05

46

Slip-Cast Superconductive Parts  

NASA Technical Reports Server (NTRS)

Complex shapes fabricated without machining. Nonaqueous slip-casting technique used to form complexly shaped parts from high-temperature superconductive materials like YBa(2)Cu(3)O(7-delta). Such parts useful in motors, vibration dampers, and bearings. In process, organic solvent used as liquid medium. Ceramic molds made by lost-wax process used instead of plaster-of-paris molds, used in aqueous slip-casting but impervious to organic solvents and cannot drain away liquid medium. Organic-solvent-based castings do not stick to ceramic molds as they do to plaster molds.

Wise, Stephanie A.; Buckley, John D.; Vasquez, Peter; Buck, Gregory M.; Hicks, Lana P.; Hooker, Matthew W.; Taylor, Theodore D.

1993-01-01

47

Routing Slips from the Computer  

ERIC Educational Resources Information Center

To facilitate the routing of periodicals, a computerized system of printing and updating routing lists was designed to replace a manual one. A computer program generates a data base of staff routing choices and prints out routing slips for each periodical. (Author/NH)

Blair, Joan

1972-01-01

48

Slip rate and tremor genesis in Cascadia  

USGS Publications Warehouse

At many plate boundaries, conditions in the transition zone between seismogenic and stable slip produce slow earthquakes. In the Cascadia subduction zone, these events are consistently observed as slow, aseismic slip on the plate interface accompanied by persistent tectonic tremor. However, not all slow slip at other plate boundaries coincides spatially and temporally with tremor, leaving the physics of tremor genesis poorly understood. Here we analyze seismic, geodetic, and strainmeter data in Cascadia to observe for the first time a large, tremor-generating slow earthquake change from tremor-genic to silent and back again. The tremor falls silent at reduced slip speeds when the migrating slip front pauses as it loads the stronger adjacent fault segment to failure. The finding suggests that rheology and slip-speed-regulated stressing rate control tremor genesis, and the same section of fault can slip both with and without detectable tremor, limiting tremor's use as a proxy for slip.

Wech, Aaron G.; Bartlow, Noel M.

2014-01-01

49

Bulk Metallic Glasses Deform via Slip Avalanches  

E-print Network

Inelastic deformation of metallic glasses occurs via slip events with avalanche dynamics similar to those of earthquakes. For the first time in these materials, measurements have been obtained with sufficiently high temporal resolution to extract both the exponents and the scaling functions that describe the nature, statistics and dynamics of the slips according to a simple mean-field model. These slips originate from localized deformation in shear bands. The mean-field model describes the slip process as an avalanche of rearrangements of atoms in shear transformation zones (STZs). Small slips show the predicted power-law scaling and correspond to limited propagation of a shear front, while large slips are associated with uniform shear on unconstrained shear bands. The agreement between the model and data across multiple independent measures of slip statistics and dynamics provides compelling evidence for slip avalanches of STZs as the elementary mechanism of inhomogeneous deformation in metallic glasses.

James Antonaglia; Wendelin J. Wright; Xiaojun Gu; Rachel R. Byer; Todd C. Hufnagel; Michael LeBlanc; Jonathan T. Uhl; Karin A. Dahmen

2013-12-21

50

Bulk Metallic Glasses Deform via Slip Avalanches  

E-print Network

Inelastic deformation of metallic glasses occurs via slip events with avalanche dynamics similar to those of earthquakes. For the first time in these materials, measurements have been obtained with sufficiently high temporal resolution to extract both the exponents and the scaling functions that describe the nature, statistics and dynamics of the slips according to a simple mean-field model. These slips originate from localized deformation in shear bands. The mean-field model describes the slip process as an avalanche of rearrangements of atoms in shear transformation zones (STZs). Small slips show the predicted power-law scaling and correspond to limited propagation of a shear front, while large slips are associated with uniform shear on unconstrained shear bands. The agreement between the model and data across multiple independent measures of slip statistics and dynamics provides compelling evidence for slip avalanches of STZs as the elementary mechanism of inhomogeneous deformation in metallic glasses.

Antonaglia, James; Gu, Xiaojun; Byer, Rachel R; Hufnagel, Todd C; LeBlanc, Michael; Uhl, Jonathan T; Dahmen, Karin A

2013-01-01

51

Slip rate and tremor genesis in Cascadia  

NASA Astrophysics Data System (ADS)

many plate boundaries, conditions in the transition zone between seismogenic and stable slip produce slow earthquakes. In the Cascadia subduction zone, these events are consistently observed as slow, aseismic slip on the plate interface accompanied by persistent tectonic tremor. However, not all slow slip at other plate boundaries coincides spatially and temporally with tremor, leaving the physics of tremor genesis poorly understood. Here we analyze seismic, geodetic, and strainmeter data in Cascadia to observe for the first time a large, tremor-generating slow earthquake change from tremor-genic to silent and back again. The tremor falls silent at reduced slip speeds when the migrating slip front pauses as it loads the stronger adjacent fault segment to failure. The finding suggests that rheology and slip-speed-regulated stressing rate control tremor genesis, and the same section of fault can slip both with and without detectable tremor, limiting tremor's use as a proxy for slip.

Wech, Aaron G.; Bartlow, Noel M.

2014-01-01

52

Slip instability and state variable friction laws  

Microsoft Academic Search

The dependence of the friction on slip history is described by an experimentally motivated constitutive law where the friction is dependent on slip rate and state variables. The state variables are defined macroscopically by evolution equations for their rates of change in terms of their present values and slip rate. Experiments may strongly suggest that one state variables is adequate

Andy Ruina

1983-01-01

53

Earthquake nucleation on dip-slip faults  

Microsoft Academic Search

The nucleation of unstable slip on a fault is of key importance in our understanding of the seismic cycle. We investigate how the asymmetric geometry of dip-slip faults affects the nucleation of unstable slip on such faults. Previous researchers have devoted much effort to understanding this nucleation process on geometrically simple faults, using a variety of frictional parameterizations. However, there

Chuanli Zhang; David D. Oglesby; Guanshui Xu

2004-01-01

54

Coseismic and postseismic slip of the 2004 Parkfield earthquake from space-geodetic data  

USGS Publications Warehouse

We invert interferometric synthetic aperture radar (InSAR) data jointly with campaign and continuous global positioning system (GPS) data for slip in the coseismic and postseismic periods of the 2004 Parkfield earthquake. The InSAR dataset consists of eight interferograms from data collected by the Envisat and Radarsat satellites spanning the time of the earthquake and variable amounts of the postseismic period. The two datasets complement each other, with the InSAR providing dense sampling of motion in the range direction of the satellite and the GPS providing more sparse, but three-dimensional measurements of ground motion. The model assumes exponential decay of the postseismic slip with a decay time constant of 0.087 years, determined from time series modeling of continuous GPS and creepmeter data. We find a geodetic moment magnitude of M 6.2 for a 1-day coseismic model and Mw 6.1 for the entire postseismic period. The coseismic rupture occurred mainly in two slip asperities; one near the hypocenter and the other 15-20 km north. Postseismic slip occurred on the shallow portions of the fault and near the rupture areas of two M 5.0 aftershocks. A comparison of the geodetic slip models with seismic moment estimates suggests that the coseismic moment release of the Parkfield earthquake is as little as 25% of the total. This underlines the importance of aseismic slip in the slip budget for the Parkfield segment.

Johanson, I. A.; Fielding, E. J.; Rolandone, F.; Burgmann, R.

2006-01-01

55

Fiber-Reinforced Slip Castings  

NASA Technical Reports Server (NTRS)

Addition of silica fibers greatly reduces shrinkage and cracking during casting of ceramics. Fiber-reinforced slip-cast silica ceramics are also tougher and have lower dielectric loss. Silica fibers are hyperpure material containing only 1 part per million total metal-ion impurities. Hyperpure fibers ensure high reflectance and allow casting to be fired at temperature greater than 2,200 degrees F without loss of strength from devitrification.

Blome, J. C.; Drennan, D. N.; Keeser, H. M.

1982-01-01

56

Origin of anomalous slip in tungsten.  

PubMed

Low-temperature deformation of body-centered cubic metals shows a significant amount of plastic slip on planes with low shear stresses, a phenomenon called anomalous slip. Despite progress in atomistic modeling of the consequences of complex stress states on dislocation mobility, the phenomenon of anomalous slip remained elusive. Using in situ Laue microdiffraction and discrete dislocation dynamics in micrometer sized tungsten single crystals, we demonstrate the occurrence of significant anomalous slip. It occurs as a consequence of cross kinks, topological configurations generated by prior dislocation interactions. This clearly identifies anomalous slip as a multidislocation process and not a property of isolated dislocations. The cross-kink mechanism also explains the ambiguous reporting of anomalous slip traces in the past and directs us to ways of including anomalous slip in continuum crystal plasticity formulations. PMID:25062203

Marichal, C; Srivastava, K; Weygand, D; Van Petegem, S; Grolimund, D; Gumbsch, P; Van Swygenhoven, H

2014-07-11

57

How do Faults Slip: Earthquakes versus Episodic Tremor and Slip  

NSDL National Science Digital Library

Despite what we have learned from the theory of plate tectonics, the specifics of how those plate motions contribute to movement along faults remain a matter of much debate. Since the discovery of plate tectonics, scientists have recognized that earthquake activity, both the orientation and magnitude, is related to plate motions. However, efforts to total up the motion simply associated with earthquakes often falls far short of the plate motions. This suggests that plates have a way to slide past one another along faults without generating earthquakes, and discovering what controls whether faults produce earthquakes is critical for better characterizing seismic hazards around the world. Scientists are using a combination of GPS and seismometer recordings to investigate this issue. Some portions of a fault reveal traditional earthquake stick-slip behavior where gradual GPS motions show the fault is locked for a long time while plate motions cause stress to accumulate at the fault until the rocks break and the fault moves over the span of minutes generating large seismic signals and an abrupt GPS motion. In 2003, researchers discovered that portions of a fault also release accumulated stress more gradually over the course of several weeks in the form of a slow slip event that is accompanied by weak seismic tremors observed in a narrow frequency range that requires specific filtering to observe. These new phenomena are described as episodic tremor and slip as they recur on nearly an annual basis, much more frequently than large earthquakes which can have recurrence intervals of 50-5000 years. To better understand how faults move, this activity will examine both GPS and seismic data in the Cascadia region to identify key observations and build interpretation from them.

Brudzinski, Mike

58

Fault roughness evolution with slip (Gole Larghe Fault Zone, Italian Alps)  

NASA Astrophysics Data System (ADS)

Fault surface roughness is a principal factor influencing fault and earthquake mechanics. However, little is known on roughness of fault surfaces at seismogenic depths, and particularly on how it evolves with accumulating slip. We have studied seismogenic fault surfaces of the Gole Larghe Fault Zone, which exploit precursor cooling joints of the Adamello tonalitic pluton (Italian Alps). These faults developed at 9-11 km and 250-300°C. Seismic slip along these surfaces, which individually accommodated from 1 to 20 m of net slip, resulted in the production of cm-thick cataclasites and pseudotachylytes (solidified melts produced during seismic slip). The roughness of fault surfaces was determined with a multi-resolution aerial and terrestrial LIDAR and photogrammetric dataset (Bistacchi et al., 2011, Pageoph, doi: 10.1007/s00024-011-0301-7). Fault surface roughness is self-affine, with Hurst exponent H < 1, indicating that faults are comparatively smoother at larger wavelengths. Fault surface roughness is inferred to have been inherited from the precursor cooling joints, which show H ? 0.8. Slip on faults progressively modified the roughness distribution, lowering the Hurst exponent in the along-slip direction up to H ? 0.6. This behaviour has been observed for wavelengths up to the scale of the accumulated slip along each individual fault surface, whilst at larger wavelengths the original roughness seems not to be affected by slip. Processes that contribute to modify fault roughness with slip include brittle failure of the interacting asperities (production of cataclasites) and frictional melting (production of pseudotachylytes). To quantify the "wear" due to these processes, we measured, together with the roughness of fault traces and their net slip, the thickness and distribution of cataclasites and pseudotachylytes. As proposed also in the tribological literature, we observe that wearing is scale dependent, as smaller wavelength asperities have a shorter interaction distance and are consumed faster with slip than larger ones. However, in faults, production of cataclasites and pseudotachylytes changes the contact area of sliding surfaces by interposing a layer of wear products. This layer may preserve from wearing asperities that are smaller in amplitude than the layer thickness, thus providing a mechanism that is likely to preserve small amplitude/wavelength roughness. These processes have been considered in a new spectral model of wear, which allows to model wear for self-affine surfaces and includes the accumulation of wear products within the fault zone. This model can be used to generalize our results and contribute to reconstruct a realistic model of a seismogenic fault zone (http://roma1.rm.ingv.it/laboratori/laboratorio-hp-ht/usems-project).

Bistacchi, A.; Spagnuolo, E.; Di Toro, G.; Nielsen, S. B.; Griffith, W. A.

2011-12-01

59

The temporal relationship between joints and faults  

NASA Astrophysics Data System (ADS)

Examples are presented of three temporal relationships between joints and faults: joints that pre-date faults; joints that are precursors to, or synchronous with, faults; and joints that post-date faults. Emphasis is placed on strike-slip faults in carbonate beds, but other examples are used. General rules are given for identifying the three temporal relationships between joints and faults. Joints that formed before faults can be dilated, sheared or affected by pressure solution during faulting, depending on their orientation in relation to the applied stress system. Faulted joints can preserve some original geometry of a joint pattern, with pinnate joints or veins commonly developing where faulted joints interact. Joints formed synchronously with faults reflect the same stress system that caused the faulting, and tend to increase in frequency toward faults. In contrast, joints that pre- or post-date faults tend not to increase in frequency towards the fault. Joints that post-date a fault may cut across or abut the fault and fault-related veins, without being displaced by the fault. They may also lack dilation near the fault, even if the fault has associated veins. Joints formed either syn- or post-faulting may curve into the fault, indicating stress perturbation around the fault. Different joint patterns may exist across the fault because of mechanical variations. Geometric features may therefore be used in the field to identify the temporal relationships between faults and joints, especially where early joints affect or control fault development, or where the distribution of late joints are influenced by faults.

Peacock, D. C. P.

2001-02-01

60

Multicycle slip distribution along a laboratory fault  

USGS Publications Warehouse

Slip distribution along a laboratory fault, which consists of eight spring-connected blocks that are elastically driven to slide on a frictional surface, has been examined for a "long' sequence of slip events to test the applicability of some conceptual models. The distributions of large slip events are found to be quite variable and do not fit the uniform slip or characteristic earthquake models. The rupture initiation points are usually not near the corresponding maximum slip points, in contrast to observations by Thatcher (1990) and by Fukao and Kikuchi (1987) that earthquake hypocenters are commonly near corresponding regions of maximum slip in the fault planes. The results suggest that earthquake prediction monitoring efforts should not be limited to a small region near an asperity but should be spread out to cover the entire fault segment in a seismic gap in order to detect the condition of simultaneous strain buildup. -from Author

Chi-Yu, King

1991-01-01

61

Animations of Episodic Tremor and Slip  

NSDL National Science Digital Library

This collection of animations shows episodic tremor and slip (slow earthquakes) from a subducting plate with locked, slow slip, and no slip zones. The first two show wood blocks being pulled over sandpaper to simulate buildup and release of strain in locked and slow slip zones of a subducting tectonic plate, and to simulate episodic movement of a subducting tectonic plate. Graphs display time versus strain or time versus distance for each of the blocks. The third animation shows a cross-section through a subducting plate illustrating the movements of a GPS station as subduction proceeds. Graphs show time versus distance under three scenarios: locked plates, slow slip, and no slip. The last animation shows horizontal movement of a GPS station as a graph displays time versus distance and a seismogram denotes shaking events.

Olds, Shelley

62

Process for slip casting textured tubular structures  

DOEpatents

A process for centrifugal slip casting a textured hollow tube. A slip made up of a carrier fluid and a suspended powder is introduced into a porous mold which is rotated at a speed sufficient to create a centrifugal force that forces the slip radially outward toward the inner surface of the mold. The suspended powder, which is formed of particles having large dimensional aspect ratios such as particles of superconductive BSCCO, settles in a textured fashion radially outward toward the mold surface. The carrier fluid of the slip passes by capillary action radially outward around the settled particles and into the absorbent mold. A layer of mold release material is preferably centrifugally slip cast to cover the mold inner surface prior to the introduction of the BSCCO slip, and the mold release layer facilitates removal of the BSCCO greenbody from the mold without fracturing.

Steinlage, Greg A. (West Lafayette, IN); Trumble, Kevin P. (West Lafayette, IN); Bowman, Keith J. (West Lafayette, IN)

2002-01-01

63

Fault slip distribution and fault roughness  

NASA Astrophysics Data System (ADS)

We present analysis of the spatial correlations of seismological slip maps and fault topography roughness, illuminating their identical self-affine exponent. Though the complexity of the coseismic spatial slip distribution can be intuitively associated with geometrical or stress heterogeneities along the fault surface, this has never been demonstrated. Based on new measurements of fault surface topography and on statistical analyses of kinematic inversions of slip maps, we propose a model, which quantitatively characterizes the link between slip distribution and fault surface roughness. Our approach can be divided into two complementary steps: (i) Using a numerical computation, we estimate the influence of fault roughness on the frictional strength (pre-stress). We model a fault as a rough interface where elastic asperities are squeezed. The Hurst exponent ?, characterizing the self-affinity of the frictional strength field, approaches ?, where ? is the roughness exponent of the fault surface in the direction of slip. (ii) Using a quasi-static model of fault propagation, which includes the effect of long-range elastic interactions and spatial correlations in the frictional strength, the spatial slip correlation is observed to scale as ?, where ? represents the Hurst exponent of the slip distribution. Under the assumption that the origin of the spatial fluctuations in frictional strength along faults is the elastic squeeze of fault asperities, we show that self-affine geometrical properties of fault surface roughness control slip correlations and that ?. Given that ? for a wide range of faults (various accumulated displacement, host rock and slip movement), we predict that ?. Even if our quasi-static fault model is more relevant for creeping faults, the spatial slip correlations observed are consistent with those of seismological slip maps. A consequence is that the self-affinity property of slip roughness may be explained by fault geometry without considering dynamical effects produced during an earthquake.

Candela, Thibault; Renard, François; Schmittbuhl, Jean; Bouchon, Michel; Brodsky, Emily E.

2011-11-01

64

Slip System Activity During Cyclic Plasticity  

NASA Astrophysics Data System (ADS)

The present investigation discusses about the occurrence and activity of slip systems in low-cycle fatigue deformation of metastable austenite (fcc) at various total strain amplitudes (? ? t) under ambient temperature, where the rate of deformation is kept constant. It has been found that with the increase in strain amplitude, the activity of the single slip system decreases and that of the multiple slip system increases.

Das, Arpan

2014-06-01

65

Episodic Tremor and Slip on a Frictional Interface with Critical Zero Weakening in Elastic Solid  

NASA Astrophysics Data System (ADS)

Non Volcanic Tremor (NVT) and related relatively weak and slow slip events, termed jointly Episodic Tremor and Slip (ETS), are observed below the seismogenic sections of numerous subduction zones and major strike-slip faults. These events have several distinguishing characteristics including moment-duration scaling relation with exponent less than 2, intermittency and flickering behavior, relatively small slip, high susceptibility for triggering, and temporal occurrence with numerous periodicities. Here we show with analytical and numerical results that a frictional fault in elastic solid with a strip below the seismogenic zone having critical zero weakening during slip provides a simple unified explanation for the diverse observed phenomena associated with ETS. The results imply that ETS have little to no predictive power on the occurrence of large events in the overriding seismogenic zone. Additional model predictions that should be tested with future high-resolution observations are fractal slip distributions and failure areas, potency/moment proportional to area and duration proportional to effective source radius (producing together the observed moment-duration scaling), discrete power law frequency-moment statistics with exponent 3/2 and exponential tapering, overall scale-invariant potency/moment time histories, and parabolic (or exponential) source time functions for event sizes measured by duration (or moment).

Ben-Zion, Y.

2010-12-01

66

Bulk metallic glasses deform via slip avalanches.  

PubMed

For the first time in metallic glasses, we extract both the exponents and scaling functions that describe the nature, statistics, and dynamics of slip events during slow deformation, according to a simple mean field model. We model the slips as avalanches of rearrangements of atoms in coupled shear transformation zones (STZs). Using high temporal resolution measurements, we find the predicted, different statistics and dynamics for small and large slips thereby excluding self-organized criticality. The agreement between model and data across numerous independent measures provides evidence for slip avalanches of STZs as the elementary mechanism of inhomogeneous deformation in metallic glasses. PMID:24785049

Antonaglia, James; Wright, Wendelin J; Gu, Xiaojun; Byer, Rachel R; Hufnagel, Todd C; LeBlanc, Michael; Uhl, Jonathan T; Dahmen, Karin A

2014-04-18

67

Stick and slip actuators (SSA)  

NASA Astrophysics Data System (ADS)

Stick and Skip Actuators (SSA) are particularly well adapted to micro- robotics. A simple design, a very high intrinsic resolution (a few nanometers) and a high rigidity make them especially interesting in high precision micro-manipulations. Moreover, a smart design allows to combine the guiding and actuating function. The mechanical interface between the piezo-elements and the guiding mechanisms in an important point of the stick and slip actuators. The design of this interface and the choice of the material are very important. Both aspects have an impact on the rigidity, which has an influence on the behavior of the actuator. They have also an incidence onf the reliability (lifetime) because the design gives the contact condition and the material the wear resistance. In addition, a loading system allowing to keep the mechanical contact at this interface has a direct effect on the contact pressure. In order to confirm the performance of SSA, prototypes have been developed at the ISR. Their designs have bene made for application in optical microscopy, for manipulators in industrial assembly of micro- engineering products, for micro-factory, chemical and bio-engineering equipment for research or routine tasks, such as testing, screening etc. This paper presents a short description of several SSA made by the IRS and describes the parameters characterizing the stick and slip motion and the mechanical interface.

Schmitt, Carl; Breguet, Jean-Marc; Bergander, Arvid; Clavel, Reymond

2000-10-01

68

Active Slip Band Separation and the Energetics of Slip in Single Crystals  

E-print Network

Active Slip Band Separation and the Energetics of Slip in Single Crystals to the prediction of stress-strain relations for single crystals and to give precise formulations of experimentally observed connec- tions between hardening of single crystals and separation of active slip

69

Active Slip Band Separation and the Energetics of Slip in Single Crystals  

E-print Network

Active Slip Band Separation and the Energetics of Slip in Single Crystals Luca Deseri David R. Owen­strain relations for single crystals and to give precise formulations of experimentally observed connec­ tions between hardening of single crystals and separation of active slip bands. Non--classical, structured

70

Episodic Tremor and Slip on the Cascadia Subduction Zone: The Chatter of Silent Slip  

Microsoft Academic Search

We found that repeated slow slip events observed on the deeper interface of the northern Cascadia subduction zone, which were at first thought to be silent, have unique nonearthquake seismic signatures. Tremorlike seismic signals were found to correlate temporally and spatially with slip events identified from crustal motion data spanning the past 6 years. During the period between slips, tremor

Garry Rogers; Herb Dragert

2003-01-01

71

Slip compensation for a Mars rover  

Microsoft Academic Search

A system that enables continuous slip compensation for a Mars rover has been designed, implemented, and field-tested. This system is composed of several components that allow the rover to accurately and continuously follow a designated path, compensate for slippage, and reach intended goals in high-slip environments. These components include: visual odometry, vehicle kinematics, a Kalman filter pose estimator, and a

Daniel M. Helmick; Yang Cheng; Daniel S. Clouse; Max Bajracharya; Larry H. Matthies; Stergios I. Roumeliotis

2005-01-01

72

September 17, 2010 SLIPS, TRIPS, FALLS PREVENTION  

E-print Network

% of all work related injuries at this location. Injury prevention is everyone's responsibility for weather conditions During wet weather use floor mats and umbrella bags at entry points to reduce water on floors Use slip resistant shoes in icy conditions (Home Health visits) SLIP and FALL PREVENTION TEAM

Leistikow, Bruce N.

73

Episodic tremor and slip on the Cascadia subduction zone: the chatter of silent slip.  

PubMed

We found that repeated slow slip events observed on the deeper interface of the northern Cascadia subduction zone, which were at first thought to be silent, have unique nonearthquake seismic signatures. Tremorlike seismic signals were found to correlate temporally and spatially with slip events identified from crustal motion data spanning the past 6 years. During the period between slips, tremor activity is minor or nonexistent. We call this associated tremor and slip phenomenon episodic tremor and slip (ETS) and propose that ETS activity can be used as a real-time indicator of stress loading of the Cascadia megathrust earthquake zone. PMID:12738870

Rogers, Garry; Dragert, Herb

2003-06-20

74

Slip-controlled thin film dynamics  

E-print Network

In this study, we present a novel method to assess the slip length and the viscosity of thin films of highly viscous Newtonian liquids. We quantitatively analyse dewetting fronts of low molecular weight polystyrene melts on Octadecyl- (OTS) and Dodecyltrichlorosilane (DTS) polymer brushes. Using a thin film (lubrication) model derived in the limit of large slip lengths, we can extract slip length and viscosity. We study polymer films with thicknesses between 50 nm and 230 nm and various temperatures above the glass transition. We find slip lengths from 100 nm up to 1 micron on OTS and between 300 nm and 10 microns on DTS covered silicon wafers. The slip length decreases with temperature. The obtained values for the viscosity are consistent with independent measurements.

R. Fetzer; M. Rauscher; A. Münch; B. A. Wagner; K. Jacobs

2006-03-17

75

[Evaporating Droplet and Imaging Slip Flows  

NASA Technical Reports Server (NTRS)

In this report, we summarize work on Evaporating Droplet and Imaging Slip Flows. The work was primarily performed by post-doc Hue Hu, and partially by grad students Lei Li and Danish Chopra. The work includes studies on droplet evaporation and its effects on temperature and velocity fields in an evaporating droplet, new 3-D microscopic particle image velocimetry and direct visualization on wall slip in a surfactant solution. With the exception of the slip measurements, these projects were those proposed in the grant application. Instead of slip flow, the original grant proposed imaging electro-osmotic flows. However, shortly after the grant was issued, the PI became aware of work on electro-osmotic flows by the group of Saville in Princeton that was similar to that proposed, and we therefore elected to carry out work on imaging slip flows rather than electro-osmotic flows.

Larson, R. G.

2002-01-01

76

Slip weakening in rocks and analog materials at co-seismic slip rates  

NASA Astrophysics Data System (ADS)

Determination of co-seismic slip resistance in earth faults is critical for understanding the magnitude of shear-stress reduction and hence the near-fault acceleration that can occur during earthquakes. Also, knowledge of shear resistance dependency on slip velocity, slip distance, normal stress, and surface roughness is fundamental information for understanding earthquake physics and the energy released during such events. In the present study, plate-impact pressure-shear friction experiments are employed to investigate the frictional resistance in fine-grained Arkansas novaculite rock and an analog material (soda-lime glass), under relevant interfacial conditions. The results of the experiments indicate that a wide range of frictional slip conditions can exist during a single slip event. These conditions range from initial no-slip followed by slip weakening, strengthening, and seizure at the frictional interface. For the case of glass vs. glass experiments, the first slip-weakening, with ? in the range of 0.4-0.2, is understood to be most likely due to thermal-induced flash heating and incipient melting at asperity junctions, while the slip-strengthening, with ? in the range of 0.1-0.4, is understood to be a result of coalescence and solidification of local melt patches. For the case of the fine grain Arkansas Novaculite rocks a similar range of slip conditions is observed.

Yuan, Fuping; Prakash, Vikas

77

Maximum slip in earthquake fault zones, apparent stress, and stick-slip friction  

USGS Publications Warehouse

The maximum slip, observed or inferred, for a small patch within the larger fault zone of an earthquake is a remarkably well-constrained function of the seismic moment. A large set of maximum slips, mostly derived from slip models of major earthquakes, indicate that this parameter increases according to the cube root of the seismic moment. Consistent with this finding, neither the average slip rate for the patches of maximum slip nor the apparent stresses of earthquakes show any systematic dependence on seismic moment. Maximum average slip rates are several meters per second independent of moment and, for earthquakes in continental crustal settings, the apparent stress is limited to about 10 MPa. Results from stick-slip friction experiments in the laboratory, combined with information about the state of stress in the crust, can be used to predict, quite closely, the maximum slips and maximum average slip rates within the fault zones of major earthquakes as well as their apparent stresses. These findings suggest that stick-slip friction events observed in the laboratory and earthquakes in continental settings, even with large magnitudes, have similar rupture mechanisms.

McGarr, A.; Fletcher, J. B.

2003-01-01

78

Effective slip-length tensor for a flow over weakly slipping stripes.  

PubMed

We discuss the flow past a flat heterogeneous solid surface decorated by slipping stripes. The spatially varying slip length, b(y), is assumed to be small compared to the scale of the heterogeneities, L, but finite. For such weakly slipping surfaces, earlier analyses have predicted that the effective slip length is simply given by the surface-averaged slip length, which implies that the effective slip-length tensor becomes isotropic. Here we show that a different scenario is expected if the local slip length has steplike jumps at the edges of slipping heterogeneities. In this case, the next-to-leading term in an expansion of the effective slip-length tensor in powers of max[b(y)/L] becomes comparable to the leading-order term, but anisotropic, even at very small b(y)/L. This leads to an anisotropy of the effective slip and to its significant reduction compared to the surface-averaged value. The asymptotic formulas are tested by numerical solutions and are in agreement with results of dissipative particle dynamics simulations. PMID:24032921

Asmolov, Evgeny S; Zhou, Jiajia; Schmid, Friederike; Vinogradova, Olga I

2013-08-01

79

Electrostatic precursors to granular slip events  

PubMed Central

It has been known for over a century that electrical signals are produced by material failure, for example during crack formation of crystals and glasses, or stick-slip motion of liquid mercury on glass. We describe here new experiments revealing that slip events in cohesive powders also produce electrical signals, and remarkably these signals can appear significantly in advance of slip events. We have confirmed this effect in two different experimental systems and using two common powdered materials, and in a third experiment we have demonstrated that similar voltage signals are produced by crack-like defects in several powdered materials. PMID:22689956

Shinbrot, Troy; Kim, Nam H.; Thyagu, N. Nirmal

2012-01-01

80

Dynamical stability of slip-stacking particles  

NASA Astrophysics Data System (ADS)

We study the stability of particles in slip-stacking configuration, used to nearly double proton beam intensity at Fermilab. We introduce universal area factors to calculate the available phase space area for any set of beam parameters without individual simulation. We find perturbative solutions for stable particle trajectories. We establish Booster beam quality requirements to achieve 97% slip-stacking efficiency. We show that slip-stacking dynamics directly correspond to the driven pendulum and to the system of two standing-wave traps moving with respect to each other.

Eldred, Jeffrey; Zwaska, Robert

2014-09-01

81

Stopping stick-slip seismic events?  

NSDL National Science Digital Library

This resource provides an abstract. This study models underground frictional resistance in stick-slip seismic events in order to determine the amount of energy needed to weaken a fault plane enough to initiate ground motion and simulate the speed of the recovery after the pressure subsides. The exact moment the slip began the maximum speed of the ground motion were detected. Results indicate that stick-slip events stop spontaneously when frictional melting begins, suggesting a potential way to stop the seismic events.

Al., Koizumi E.; Agu

82

Slow slip event at Kilauea Volcano  

USGS Publications Warehouse

Early in the morning of 1 February 2010 (UTC; early afternoon 31 January 2010 local time), continuous Global Positioning System (GPS) and tilt instruments detected a slow slip event (SSE) on the south flank of Kilauea volcano, Hawaii. The SSE lasted at least 36 hours and resulted in a maximum of about 3 centimeters of seaward displacement. About 10 hours after the start of the slip, a flurry of small earthquakes began (Figure 1) in an area of the south flank recognized as having been seismically active during past SSEs [Wolfe et al., 2007], suggesting that the February earthquakes were triggered by stress associated with slip [Segall et al., 2006].

Poland, Michael P.; Miklius, Asta; Wilson, J. David; Okubo, Paul G.; Montgomery-Brown, Emily; Segall, Paul; Brooks, Benjamin; Foster, James; Wolfe, Cecily; Syracuse, Ellen; Thurbe, Clifford

2010-01-01

83

Electrostatic precursors to granular slip events.  

PubMed

It has been known for over a century that electrical signals are produced by material failure, for example during crack formation of crystals and glasses, or stick-slip motion of liquid mercury on glass. We describe here new experiments revealing that slip events in cohesive powders also produce electrical signals, and remarkably these signals can appear significantly in advance of slip events. We have confirmed this effect in two different experimental systems and using two common powdered materials, and in a third experiment we have demonstrated that similar voltage signals are produced by crack-like defects in several powdered materials. PMID:22689956

Shinbrot, Troy; Kim, Nam H; Thyagu, N Nirmal

2012-07-01

84

Joint Occupancy.  

ERIC Educational Resources Information Center

This annotated bibliography includes summaries of 15 articles and reports dealing with the joint use of buildings and facilities by schools and other public or private organizations. An introductory section describes the historical origins and development of the joint occupancy concept and examines the various economic and philosophical arguments…

Higham, Charlene Ellison

85

Ceramic joints  

DOEpatents

Butt joints between materials having different coefficients of thermal expansion are prepared having a reduced probability of failure of stress facture. This is accomplished by narrowing/tapering the material having the lower coefficient of thermal expansion in a direction away from the joint interface and not joining the narrow-tapered surface to the material having the higher coefficient of thermal expansion.

Miller, Bradley J. (Worcester, MA); Patten, Jr., Donald O. (Sterling, MA)

1991-01-01

86

Slip compensation at fault damage zones along earthquake surface ruptures  

NASA Astrophysics Data System (ADS)

Surface ruptures associated with earthquake faulting commonly comprise a number of segments, and the discontinuities form tip and linking damage zones, which are deformed regions consisting of secondary features. Stress transferring or releasing, when seismic waves pass through the discontinuities, could produce different slip features depending on rupture propagation or termination. Thus, slip patterns at fault damage zones can be one of the key factors to understand fault kinematics, fault evolution and, hence, earthquake hazard. In some previous studies (e.g. Peacock and Sanderson, 1991; Kim and Sanderson, 2005), slip distribution along faults to understand the connectivity or maturity of segmented faults system have commonly been analyzed based on only the main slip components (dip-slip or strike-slip). Secondary slip components, however, are sometimes dominant at fault damage zones, such as linkage and tip zones. In this study, therefore, we examine slip changes between both main and secondary slip components along unilaterally propagated coseismic strike-slip ruptures. Horizontal and vertical components of slip and the slip compensation patterns at tip and linking damage zones are various from slip deficit (decrease in both slip components) through slip compensation (increase of vertical slip with horizontal slip decrease) to slip neutral. Front and back tip zones, which are classified depending on main propagation direction of earthquake ruptures, show different slip patterns; slip compensation is observed at the frontal tip whilst slip deficit occurs at the back tip zone. Average values of the two slip components and their compensative patterns at linking damage zones are closely related with the ratio of length to width (L/W) of linkage geometry; the horizontal slip is proportional to the ratio of L/W, whilst the vertical slip shows little dependence on the value L/W. When the L/W is greater than ~2, average values of two slip components are almost similar to those of the main traces. In contrast, when the L/W < 2, the vertical slip is either increased or decreased as the horizontal slip is decreased, depending on the maturity of the linking zone. Thus, we argue that slip patterns at linking damage zones may be controlled by the LW-ratio of linking damage zones and hence structural maturities of the segmented fault systems. In conclusion, slip patterns at fault damage zones along earthquake surface ruptures are various depending on the maturity of linkage zones and/or the rupture propagation direction. Therefore, the consideration of slip compensation as well as damage structures along surface ruptures must be very useful to understand fault evolution and, hence, to assess seismic hazards around active fault systems.

Choi, J.; Kim, Y.

2013-12-01

87

Methodology for the interpretation of fault-slip seismicity in a weak shear zone  

NASA Astrophysics Data System (ADS)

Fault-slip related seismic events that occur in underground mines could inflict severe damage to underground openings; thus a proper estimation of fault-slip potential in active mining areas is of paramount importance in assessing its risk. It is not uncommon in underground mines that large seismic events take place away from stopes being extracted, where fault-slip potential is presumed not to be high enough to result in those seismic events. In the present paper, fault-slip related seismic events taking place within a weak shear zone in Garson Mine, Sudbury, Canada are investigated. First, in order to understand the stress states of rockmass in the mine, numerical analysis is carried out with a 3D mine-wide model whilst assuming isotropic elasticity. The result obtained from the analysis reveals that the shear stress of rockmass in a weak shear zone does not reach the maximum shear strength determined by Mohr-Coulomb failure criterion with basic friction angles of the rockmass. The result contradicts a fact that quite a few seismic events have been actually recorded in the regions with micro seismic monitoring systems installed in the mine. As an interpretation of that, it is postulated that variations in shear stiffness within the shear zone contribute to the generation of high slip potential resulting in the occurrence of those seismic events. In order to justify the postulation, numerical analysis is additionally carried out, in which the shear zone is modelled with transversely isotropic models, of which shear stiffness is decreased in the same direction as a measured joint orientation in the shear zone. For source regions of those seismic events, isotropic models are used without decreasing its shear stiffness, thus resulting in the discrepancy in shear stiffness between the source regions and other areas in the shear zone. The result obtained from the analysis verifies that fault-slip potential drastically increases within the source regions due to the difference in shear stiffness. It is further found out from dynamic analysis in which fault-slip is simulated with Barton's shear strength model that the increasing slip potential is high enough to cause large seismic events in the regions. In the present study, the interpretation of seismic events occurring within a weak shear zone is provided, and a methodology to simulate high fault-slip potential that could be generated within the shear zone is developed. The methodology can be used with back analysis to determine the mechanical properties of the weak shear zone, which lead to the better estimation of fault-slip potential.

Sainoki, Atsushi; Mitri, Hani S.

2014-11-01

88

Beyond the no-slip boundary condition  

E-print Network

This paper offers a simple macroscopic approach to the question of the slip boundary condition to be imposed upon the tangential component of the fluid velocity at a solid boundary. Plausible reasons are advanced for ...

Brenner, Howard

89

Bone scintigraphy in slipped capital femoral epiphysis  

SciTech Connect

Tc-/sub 99m/ diphosphonate bone scans were performed on 11 children with slipped capital femoral epiphysis. On pinhole hip images, seven hips in seven patients had increased radionuclide uptake in the physis and adjacent proximal femoral metaphysis where the slip had occurred. Three hips in three patients had decreased radionuclide uptake in the femoral head on the side of the slipped epiphysis, indicating compromise of the femoral head blood supply. Three or more months following internal fixation, three children had scintigraphy that showed loss of the usual focal uptake in the physis and adjacent proximal femoral metaphysis. Bone scintigraphy in pediatric patients with slipped capital femoral epiphysis is valuable in defining the metabolic status of the femoral head. Absence of radiopharmaceutical uptake in the affected femoral head indicates that the femoral head is at risk for development of radiographic changes associated with aseptic necrosis.

Gelfand, M.J.; Strife, J.L.; Graham, E.J.; Crawford, A.H.

1983-12-01

90

7 CFR 51.491 - Wet slip.  

Code of Federal Regulations, 2011 CFR

...Wet slip means a condition present at time of packing in which the stem scar is abnormally large, excessively wet and slippery, yields...frequently accompanied by fresh radial growth cracks at the edge of the stem...

2011-01-01

91

The distributions of slip rate and ductile deformation in a strike-slip shear zone  

Microsoft Academic Search

SUMMARY A simple mechanical model and dimensional analysis are used to derive a scaling law for the partitioning between slip rate on a strike-slip fault and distributed deformation in the far-field. The depth of the fault, the distributions of stress, strain rate and slip rate are solved for a given far-field force or displacement in a 2-D medium with a

Frédérique Rolandone; Claude Jaupart

2002-01-01

92

Effects of interlayer slip on multilayered folds  

E-print Network

of interlayer slip. The specimen is jacketed with three layers of thermo-shrink polyolefin tubing to isolate it from the confining fluid. Experimental Conditions All specimens are shortened parallel to the long axis of the multilayer specimen assemblage... of interlayer slip. The specimen is jacketed with three layers of thermo-shrink polyolefin tubing to isolate it from the confining fluid. Experimental Conditions All specimens are shortened parallel to the long axis of the multilayer specimen assemblage...

Casarta, Lawrence Joseph

2012-06-07

93

Friction, Stick-Slip Motion and Earthquake  

Microsoft Academic Search

Friction has close relation to Earthquake [1, 2]. When the friction between two solids shows velocity weakening behavior,\\u000a stationary motion becomes unstable and stick-slip motion appears, which repeats stopping and fast moving states. Earthquake\\u000a is a kind of stick-slip motion. Figure 1 shows tectonic plates around Japan. The pacific ocean plate goes down below the land\\u000a plate and drags the

H. Matsukawa; T. Saito

94

Stalled slip during the 2011 Cascadia ETS event  

NASA Astrophysics Data System (ADS)

In regions with Episodic Tremor and Slip (ETS), such as Cascadia and southwest Japan, behavior can range from large events where both phenomena migrate together for 100s of kilometers along strike, to smaller tremor swarms without geodetically detected slip. Slip without tremor, while observed elsewhere, has not been seen large ETS in Cascadia. However, recent observations have identified slip during the 2011 Cascadia ETS event that did not generate tremor (see the 'Episodic silence and slip' presentation by Wech & Bartlow). Here we expand on that analysis to present details of the inversion of GPS data from this event using the Network Inversion Filter (Segall and Matthews, 1997). We find that in the middle of the 2011 ETS event there are about 20 days of tremor-less slip, with slip occurring at a much lower slip-rate than typical ETS slip in Cascadia. During this time slip is also 'stalled' in place, with little to no migration along strike. Slip-rate and propagation rate are theoretically proportional (Rubin, G3, 2011), consistent with the low slip-rate and 'stalled' nature of the observed tremorless slip. This finding demonstrates that Cascadia may exhibit a wider range of slow slip behavior than previously recognized, and may imply a minimum slip-rate for tremor generation. In this presentation we will discuss details of the slip inversion, including resolution, the range of models that fit the data, and a comparison of time-dependent vs. static inversions.

Bartlow, N. M.; Wech, A.; Segall, P.

2013-12-01

95

Nonlinear dynamical triggering of slow slip  

SciTech Connect

Among the most fascinating, recent discoveries in seismology have been the phenomena of triggered slip, including triggered earthquakes and triggered-tremor, as well as triggered slow, silent-slip during which no seismic energy is radiated. Because fault nucleation depths cannot be probed directly, the physical regimes in which these phenomena occur are poorly understood. Thus determining physical properties that control diverse types of triggered fault sliding and what frictional constitutive laws govern triggered faulting variability is challenging. We are characterizing the physical controls of triggered faulting with the goal of developing constitutive relations by conducting laboratory and numerical modeling experiments in sheared granular media at varying load conditions. In order to simulate granular fault zone gouge in the laboratory, glass beads are sheared in a double-direct configuration under constant normal stress, while subject to transient perturbation by acoustic waves. We find that triggered, slow, silent-slip occurs at very small confining loads ({approx}1-3 MPa) that are smaller than those where dynamic earthquake triggering takes place (4-7 MPa), and that triggered slow-slip is associated with bursts of LFE-like acoustic emission. Experimental evidence suggests that the nonlinear dynamical response of the gouge material induced by dynamic waves may be responsible for the triggered slip behavior: the slip-duration, stress-drop and along-strike slip displacement are proportional to the triggering wave amplitude. Further, we observe a shear-modulus decrease corresponding to dynamic-wave triggering relative to the shear modulus of stick-slips. Modulus decrease in response to dynamical wave amplitudes of roughly a microstrain and above is a hallmark of elastic nonlinear behavior. We believe that the dynamical waves increase the material non-affine elastic deformation during shearing, simultaneously leading to instability and slow-slip. The inferred triggered slow-slip on the San Andreas Fault at Parkfield, CA., due to December, 2003 Mw6.5 San Simeon Earthquake (Breguier et al., Science 321, p.1478, 2008) shows very similar characteristics to what we observe in the laboratory, suggesting an extremely low in situ effective stress or a weak fault and a nonlinear-dynamical triggering mechanism.

Johnson, Paul A [Los Alamos National Laboratory; Knuth, Matthew W [WISCONSIN; Kaproth, Bryan M [PENN STATE; Carpenter, Brett [PENN STATE; Guyer, Robert A [Los Alamos National Laboratory; Le Bas, Pierre - Yves [Los Alamos National Laboratory; Daub, Eric G [Los Alamos National Laboratory; Marone, Chris [PENN STATE

2010-12-10

96

Nonlinear Dynamical Triggering of Slow-Slip  

NASA Astrophysics Data System (ADS)

Among the most fascinating, recent discoveries in seismology have been the phenomena of triggered slip, including triggered earthquakes and triggered-tremor, as well as triggered slow, silent-slip during which no seismic energy is radiated. Because fault nucleation depths cannot be probed directly, the physical regimes in which these phenomena occur are poorly understood. Thus determining physical properties that control diverse types of triggered fault sliding and what frictional constitutive laws govern triggered faulting variability is challenging. We are characterizing the physical controls of triggered faulting with the goal of developing constitutive relations by conducting laboratory and numerical modeling experiments in sheared granular media at varying load conditions. In order to simulate granular fault zone gouge in the laboratory, glass beads are sheared in a double-direct configuration under constant normal stress, while subject to transient perturbation by acoustic waves. We find that triggered, slow, silent-slip occurs at very small confining loads (~1-3 MPa) that are smaller than those where dynamic earthquake triggering takes place (4-7 MPa), and that triggered slow-slip is associated with bursts of LFE-like acoustic emission. Experimental evidence suggests that the nonlinear dynamical response of the gouge material induced by dynamic waves may be responsible for the triggered slip behavior: the slip-duration, stress-drop and along-strike slip displacement are proportional to the triggering wave amplitude. Further, we observe a shear-modulus decrease corresponding to dynamic-wave triggering relative to the shear modulus of stick-slips. Modulus decrease in response to dynamical wave amplitudes of roughly a microstrain and above is a hallmark of elastic nonlinear behavior. We believe that the dynamical waves increase the material non-affine elastic deformation during shearing, simultaneously leading to instability and slow-slip. The inferred triggered slow-slip on the San Andreas Fault at Parkfield, CA., due to December, 2003 Mw6.5 San Simeon Earthquake (Breguier et al., Science 321, p.1478, 2008) shows very similar characteristics to what we observe in the laboratory, suggesting an extremely low in situ effective stress or a weak fault and a nonlinear-dynamical triggering mechanism [We gratefully acknowledge the support of the U. S. Department of Energy through the LANL/LDRD Program for this work].

Johnson, P. A.; Knuth, M. W.; Kaproth, B. M.; Carpenter, B. M.; Guyer, R. A.; Le Bas, P.; Daub, E. G.; Marone, C.

2010-12-01

97

Digital slip frequency generator and method for determining the desired slip frequency  

DOEpatents

The output frequency of an electric power generator is kept constant with variable rotor speed by automatic adjustment of the excitation slip frequency. The invention features a digital slip frequency generator which provides sine and cosine waveforms from a look-up table, which are combined with real and reactive power output of the power generator.

Klein, Frederick F. (Monroeville, PA)

1989-01-01

98

Spacetime correlation of slip and tremor during the 2009 Cascadia slow slip event  

E-print Network

transient deformations accompanied by emergent, lowfrequency tremor occurs in subduction zones around the Cascadia sub- duction zone in the Pacific Northwest of the U.S. [3] ETS events repeat rather periodicallySpacetime correlation of slip and tremor during the 2009 Cascadia slow slip event Noel M. Bartlow,1

Segall, Paul

99

Mechanics, slip behavior, and seismic potential of corrugated dip-slip faults  

NASA Astrophysics Data System (ADS)

To better understand the mechanics and seismic potential of nonplanar fault surfaces, we present results from a suite of numerical models of faults with sinusoidal corrugations in the downdip direction. Systematic variations in corrugation wavelength, amplitude, and loading angle are introduced to determine the effects on slip behavior and seismic moment release. We find that corrugated faults, in general, slip less than planar faults. Changes in slip behavior are nearly scale-independent and are dominantly controlled by the amplitude/wavelength of corrugations. Model results suggest that obliquely loaded corrugated faults accumulate less strike slip than a planar fault with the same tip line dimensions and average orientation. This result implies that slip direction is not a reliable indicator of regional stress direction and may at least partially explain repeated, nearly pure dip-slip coseismic events at oblique plate boundaries. Though the scalar seismic moment release is always less for corrugated fault surfaces due to a greater reduction in slip compared to increased surface area, for geologically reasonable corrugation geometries, changes in total scalar moment release are not significantly different than planar faults. Techniques that utilize highly simplified fault geometries may therefore accurately reproduce scalar moment release but will nonetheless incorrectly predict coseismic slip magnitudes and distributions, as well as regional stress orientations.

Marshall, Scott T.; Morris, Anna C.

2012-03-01

100

Prediction of slips: an evaluation of utilized coefficient of friction and available slip resistance  

Microsoft Academic Search

The purpose of this study was to investigate the relationship between measures of floor surface slip resistance and an individual's peak utilized coefficient of friction (COFU) on the probability of a slip occurring during level walking. Video, kinematic and ground reaction force data were recorded simultaneously as subjects walked at a self-selected speed during conditions of normal and reduced floor

J. M. Burnfield; C. M. Powers

2006-01-01

101

Slip partitioning along major convergent plate boundaries  

NASA Astrophysics Data System (ADS)

Along plate boundaries characterized by oblique convergence, earthquake slip vectors are commonly rotated toward the normal of the trench with respect to predicted plate motion vectors. Consequently, relative plate motion along such convergent margins must be partitioned between displacements along the thrust plate interface and deformation within the forearc and back-arc regions. The deformation behind the trench may take the form of strike-slip motion, back-arc extension, or some combination of both. We observe from our analysis of the Harvard Moment Tensor Catalog that convergent arcs characterized by back-arc spreading, specifically the Marianas and New Hebrides, are characterized by a large degree of slip partitioning. However, the observed rates, directions, and location of back-arc spreading are not sufficient to account for degree of partitioning observed along the respective arcs, implying that the oblique component of subduction is also accommodated in part by shearing of the overriding plate. In the case of the Sumatran arc, where partitioning is accommodated by strike-slip faulting in the overriding plate, the degree of partitioning is similar to that observed along the Marianas, but the result is viewed with caution because it is based on a predicted plate motion vector that is based on locally derived earthquake slip vectors. In the case of the Alaskan-Aleutian arc, where back-arc spreading is also absent, the degree of partitioning is less and rotation of slip vectors toward the trench normal appears to increase linearly as a function of the obliquity of convergence. If partitioning in the Alaskan-Aleutian arc is accommodated by strike-slip faulting within the upper plate, the positive relationship between obliquity of convergence and the rotation of earthquake slip vectors to the trench normal may reflect that either (1) the ratio of the depth extent of strike-slip faults behind the trench Z s to the subduction thrust Z t increases westward along the arc, (2) the dip of the subduction thrust increases westward along the arc, or (3) the strength of the subduction thrust decreases westward along the arc.

Yu, Guang; Wesnousky, Steven G.; Ekström, Göran

1993-06-01

102

Slip casting of partially stabilized zirconia  

SciTech Connect

The toughness of partially-stabilized zirconia has been studied for some time. The tetragonal phase in partially stabilized ZrO2 transforms to the monoclinic phase under the influence of stress. Partially-stabilized ZrO2 has enhanced tensile strength, good wear resistance and low friction coefficient, and has found industrial applications. This article describes the use of partially-stabilized zirconia in slip casting. Lab techniques of slip casting have been reported for nonplastic materials such as Al2O3, CaF2, CaO-stabilized ZrO2 and MgO. The article discusses the variation of slip density and firing temperature and also reports the preparation of specimens of CaOstabilized ZrO2 by slip casting from ethanol-based suspensions. The preparation of Y2O3-ZrO2 compositions by slip casting from aqueous suspension is also reported. A Y2O3 partially stabilized ZrO2 powder was used as a starting material. The densities of the cast specimens were measured from the volume and weight, and those of the sintered specimens were measured by a liquid displacement technique using distilled water. The concentation of the suspension strongly affects the relative density of the cast specimen and the firing shrinkage of the sintered specimen, while the relative density of the sintered specimen is independent of the concentration of the suspension.

Taguchi, H.; Miyamoto, H.; Takahashi, Y.

1985-02-01

103

The mechanics of stick-slip  

USGS Publications Warehouse

Physical mechanisms that have been proposed to explain the occurrence of stick-slip motion during frictional sliding have been examined in the light of results obtained from experiments with rocks and brittle minerals. An instability caused by sudden brittle fracture of locked regions on surfaces in contact is the most likely explanation for stick-slip during dry frictional sliding of brittle rocks at room temperature. Areas requiring further study and the uncertainties in applying the results of laboratory experiments to earthquake studies are emphasized. ?? 1970.

Byerlee, J. D.

1970-01-01

104

Complementary slip distributions of the largest earthquakes in the 2012 Brawley swarm, Imperial Valley, California  

NASA Astrophysics Data System (ADS)

We investigate the finite rupture processes of two M > 5 earthquakes in the 2012 Brawley swarm by joint inversion of nearby strong motion and high-rate GPS data. Waveform inversions up to 3 Hz were made possible by using a small event (Mw3.9) for path calibration of the velocity structure. Our results indicate that the first (Mw5.3) event ruptured a strong, concentrated asperity with offsets of ~20 cm centered at a depth of 5 km. The subsequent Mw5.4 event occurred 1.5 h later with a shallower slip distribution that surrounds and is complementary to that of the earlier event. The second event has a longer rise time and weaker high-frequency energy release compared to the Mw5.3 event. Both events display strong rupture directivity toward the southwest and lack of very shallow (<2 km) coseismic slip. The hypocenters for these events appear to be near or in the bedrock, but most of the slip is distributed at shallower depths (<6 km) and can explain a large part of the GPS offsets for the swarm. The complementary slip distributions of the two events suggest a triggering relationship between them with no significant creep needed to explain the various data sets.

Wei, Shengji; Helmberger, Don; Owen, Susan; Graves, Robert W.; Hudnut, Kenneth W.; Fielding, Eric J.

2013-03-01

105

GENERALIZATION OF TREADMILL-SLIP TRAINING TO PREVENT A FALL FOLLLOWING A SUDDEN (NOVEL) SLIP IN OVER-GROUND WALKING  

PubMed Central

The purposes of the study were to determine 1) whether treadmill-slip training could reduce the likelihood of falls during a novel slip in over-ground walking, and 2) to what extent such (indirect) training would be comparable to (direct) over-ground-slip training. A treadmill-slip training group (Group A, n=17) initially experienced repeated perturbations on treadmill intended to simulate forward-slip in over-ground walking. Perturbation continued and its intensity reduced when necessary to ensure subjects’ successful adaptation (i.e., when they could land their trailing foot ahead of the slipping foot in at least 3 of 5 consecutive trials). They then experienced a novel slip during over-ground walking. Another 17 young adults in Group B experienced an identical novel slip that served as the controls. They then underwent more slip trials during over-ground walking. Their 16th slip trial was analyzed to represent the over-ground-slip training effect. Eight subjects (47%) in Group A fell upon their first treadmill slip, while all adapted successfully after a minimum of 15 slip trials. Upon the novel slip during over-ground walking, none of them fell in comparison to four subjects (23.5%) fell in Group B upon the same trial (p<0.05). Group A’s control of stability, both proactive and reactive, was significantly better than that of Group B’s on their first over-ground slip, while the level of improvement derived from indirect treadmill training was not as strong as that from direct over-ground-slip training, as demonstrated in Group B’s 16th slip trial (p<0.001). These results clearly demonstrated the feasibility of fall reduction through treadmill-slip training. PMID:23141636

Yang, Feng; Bhatt, Tanvi; Pai, Yi-Chung

2012-01-01

106

Joint hypermobility  

Microsoft Academic Search

Joint hypermobility is an area of neglect in rheumatology. That is not to say it is overlooked by rheumatologists. It is spotted when sought, but for many unfortunate patients, here the story ends. The act of recognition becomes the goal in itself rather than the medium through which effective therapy can be provided. This chapter serves to reinforce the clinical

Rodney Grahame

2003-01-01

107

Postradiation slipped capital femoral epiphyses (SCFE)  

SciTech Connect

This study details the case reports of two children who developed slipped capital femoral epiphyses (SCFE) after receiving external irradiation. The clinical and diagnostic features of postradiation SCFE are reviewed and discussed. Guidelines for the management of children who receive pelvic irradiation are presented.

Sabio, H.; Sussman, M.; Levien, M.

1987-09-01

108

Slip complexity in earthquake fault models.  

PubMed

We summarize studies of earthquake fault models that give rise to slip complexities like those in natural earthquakes. For models of smooth faults between elastically deformable continua, it is critical that the friction laws involve a characteristic distance for slip weakening or evolution of surface state. That results in a finite nucleation size, or coherent slip patch size, h*. Models of smooth faults, using numerical cell size properly small compared to h*, show periodic response or complex and apparently chaotic histories of large events but have not been found to show small event complexity like the self-similar (power law) Gutenberg-Richter frequency-size statistics. This conclusion is supported in the present paper by fully inertial elastodynamic modeling of earthquake sequences. In contrast, some models of locally heterogeneous faults with quasi-independent fault segments, represented approximately by simulations with cell size larger than h* so that the model becomes "inherently discrete," do show small event complexity of the Gutenberg-Richter type. Models based on classical friction laws without a weakening length scale or for which the numerical procedure imposes an abrupt strength drop at the onset of slip have h* = 0 and hence always fall into the inherently discrete class. We suggest that the small-event complexity that some such models show will not survive regularization of the constitutive description, by inclusion of an appropriate length scale leading to a finite h*, and a corresponding reduction of numerical grid size. PMID:11607669

Rice, J R; Ben-Zion, Y

1996-04-30

109

Slip Complexity in Earthquake Fault Models  

NASA Astrophysics Data System (ADS)

We summarize studies of earthquake fault models that give rise to slip complexities like those in natural earthquakes. For models of smooth faults between elastically deformable continua, it is critical that the friction laws involve a characteristic distance for slip weakening or evolution of surface state. That results in a finite nucleation size, or coherent slip patch size, h*. Models of smooth faults, using numerical cell size properly small compared to h*, show periodic response or complex and apparently chaotic histories of large events but have not been found to show small event complexity like the self-similar (power law) Gutenberg-Richter frequency-size statistics. This conclusion is supported in the present paper by fully inertial elastodynamic modeling of earthquake sequences. In contrast, some models of locally heterogeneous faults with quasi-independent fault segments, represented approximately by simulations with cell size larger than h* so that the model becomes ``inherently discrete,'' do show small event complexity of the Gutenberg-Richter type. Models based on classical friction laws without a weakening length scale or for which the numerical procedure imposes an abrupt strength drop at the onset of slip have h* = 0 and hence always fall into the inherently discrete class. We suggest that the small-event complexity that some such models show will not survive regularization of the constitutive description, by inclusion of an appropriate length scale leading to a finite h*, and a corresponding reduction of numerical grid size.

Rice, James R.; Ben-Zion, Yehuda

1996-04-01

110

Slip dynamics at a patterned rubber/glass interface during stick-slip motions.  

PubMed

We report on an experimental study of heterogeneous slip instabilities generated during stick-slip motions at a contact interface between a smooth rubber substrate and a patterned glass lens. Using a sol-gel process, the glass lens is patterned with a lattice of parallel ridges (wavelength, 1.6 ?m, amplitude 0.35 ?m). Friction experiments using this patterned surface result in the systematic occurrence of stick-slip motions over three orders of magnitude in the imposed driving velocity while stable friction is achieved with a smooth surface. Using a contact imaging method, real-time displacement fields are measured at the surface of the rubber substrate. Stick-slip motions are found to involve the localized propagation of transverse interface shear cracks whose velocity is observed to be remarkably independent on the driving velocity. PMID:22972225

Audry, M C; Fretigny, C; Chateauminois, A; Teissere, J; Barthel, E

2012-09-01

111

Joint Replacement (Finger and Wrist Joints)  

MedlinePLUS

... A-Z Hand Anatomy Find a Hand Surgeon Joint Replacement Email to a friend * required fields From * To * ... be possible to treat arthritic joints surgically, including “joint replacement” procedures. What does it mean to have a “ ...

112

A STUDY ON HIGH STRENGTH BOLTED JOINT WITH METAL-SPRAYED CONTACT SURFACES  

NASA Astrophysics Data System (ADS)

Slip coefficient of high-strength bolt friction joints is well known to depend on the condition of contact surfaces. The coefficient is determined as 0.4 in the Specifications for Highway Bridges and the Design Standards for Railway Structures and Commentary (Steel Structures) in Japan, in the condition of roughened contact surfaces with mill scale removed or painted contact surfaces with inorganic zinc rich paint. However, the slip coefficient with metal-sprayed surfaces is not clear. For the joints with metalsprayed surfaces, hot-dip galvanized bolts are applied and such bolts are tightened by turn-of-nut method. However, it is unclear how much axial force is induced into the bolts in the joints with metal-sprayed surfaces. In order to examine slip coefficient of the bolted joints with metal-sprayed contact surfaces slip tests of high strength bolted joints were carried out. On the basis of above examinations, the slip coefficient with metal-sprayed surfaces is proposed in this paper. To clarify the induced axial force of the bolts, bolt-tightening tests were carried out. Considering bolt diameter, bolt length, induced axial forces and their relaxation, nut rotation angles are proposed in relation to different bolt size.

Minami, Kuniaki; Saito, Masamichi; Yokoyama, Hideki; Sugimoto, Ichiro; Nojima, Takao; Masunaga, Toshihiko; Nagasaki, Eiji

113

PROCESS INTENSIFIED GREEN REACTION CHEMISTRIES PERFORMED IN THE SPINNING TUBE-IN-TUBE (STT®) REACTOR  

EPA Science Inventory

The U. S. Environmental Protection Agency (USEPA) and Kreido Laboratories have established a Cooperative Research and Development Agreement (CRADA) collaboration, to develop and commercialize green and sustainable chemistries in the area of industrial chemical synthesis. Utilizi...

114

GREEN REACTION CHEMISTRIES PERFORMED IN THE SPINNING TUBE-IN-TUBE (STT) REACTOR  

EPA Science Inventory

The U. S. Environmental Protection Agency (USEPA) and Kreido Laboratories have established a Cooperative Research and Development Agreement (CRADA) collaboration, to develop and commercialize green and sustainable chemistries in the area of industrial chemical synthesis. Utilizi...

115

Organic Synthesis in a Spinning Tube-in-Tube (STT¢) Reactor  

EPA Science Inventory

Continuous-flow reactors have been designed to minimize and potentially overcome the limitations of heat and mass transfer that are encountered in chemical reactors and further experienced upon scale up of a reaction. With process intensification, optimization of the reaction i...

116

Joint hypermobility.  

PubMed

Joint hypermobility is an area of neglect in rheumatology. That is not to say it is overlooked by rheumatologists. It is spotted when sought, but for many unfortunate patients, here the story ends. The act of recognition becomes the goal in itself rather than the medium through which effective therapy can be provided. This chapter serves to reinforce the clinical and epidemiological importance of a common disorder whose significance is under-appreciated and impact largely ignored. In contradistinction to our earlier chapter, published in 2000, which took for its remit the heritable disorders of connective tissue in general, the current one focuses on the commonly encountered (so-called benign) joint hypermobility syndrome, its recognition, epidemiology, clinical features and management according to the most recent literature. PMID:15123047

Hakim, Alan; Grahame, Rodney

2003-12-01

117

What do formal inversions of space geodetic data tell us about fault slip rates? Examples from Southern California. (Invited)  

NASA Astrophysics Data System (ADS)

We use secular velocities from the continuous GPS data provided by the Plate Boundary Observatory (PBO) and Scripps Orbit Permanent Array Center (SOPAC), campaign GPS data (SCEC Crustal Motion Model) and InSAR data from the ERS-1/2 and ENVISAT satellites spanning nearly 20 years (1992-2010) to estimate the contemporaneous slip rates and locking depths on the Southern San Andreas fault (SAF), the San Jacinto fault (SJF) and the Elsinore fault. The model parameter space was interrogated using a Gibbs sampler, a Markov chain Monte Carlo algorithm which naturally approximates the joint probability distribution for the model parameters and allows for a formal evaluation of model uncertainties and trade-offs. We performed joint inversions of all available space geodetic data using the Savage and Burford (1973) dislocation model. Previous geodetic estimates of slip rates in this region based on dislocation models have generally inferred a higher slip velocity on the SAF (21-26 mm/yr), and a lower velocity on the SJF (12-19 mm/yr) (Becker et al. 2005, Fay and Humphreys 2005, Meade and Hager 2005, Fialko 2006). These "geodetic" slip rates are generally higher than geologic estimates representing average slip rates on time scales of 10^4-10^6 years. We investigate implications of fault geometry such as a non-vertical SAF and a "blind" segment of the SJF (Fialko 2006; Lin et al. 2007). Using the fault geometry motivated by these recent studies, we estimate a slip rate of 16(+/-2) mm/yr for the southern SAF, and a combined slip rate of 21(+/-3) mm/yr for the two closely spaced branches of the southern San Jacinto fault (the Coyote Creek fault and the blind southern continuation of the Clark fault). The locking depths are estimated at 7(+/-3) km and 14(+/-6) km for the SAF and SJF, respectively. For the SJF, we note a significant trade-off between fault velocity and locking depth, with the best-fitting values occurring at the lower end of the formally estimated parameter ranges: 19 mm/yr and 11 km, respectively. We also investigate the effect of elastic heterogeneities on the preferred fault slip rate and locking depth. We use the elastic structure inferred from seismic body wave tomography. The forward model incorporating the effects of elastic heterogeneities is based on the fictitious body force technique of Barbot et al. (2009). As the steady-state interseismic velocity field is computed using a superposition of "seismic" slip in the upper crust and the rigid block motion, these calculations are also relevant for coseismic deformation in heterogeneous elastic media.

Lindsey, E. O.; Fialko, Y.

2010-12-01

118

Constraining fault constitutive behavior with slip and stress heterogeneity  

E-print Network

Constraining fault constitutive behavior with slip and stress heterogeneity B. T. Aagaard1 and T. H and postshear stress on a fault can be used to constrain fault constitutive behavior beyond that required on a vertical, planar strike-slip fault show that the conditions that lead to slip heterogeneity remain in place

Greer, Julia R.

119

Shear-Dependent Boundary Slip in an Aqueous Newtonian Liquid  

Microsoft Academic Search

We report direct measurements of hydrodynamic drainage forces, which show clear evidence of boundary slip in a Newtonian liquid. The degree of boundary slip is found to be a function of the liquid viscosity and the shear rate, as characterized by the slip length, and is up to â20 nm . This has implications for confined biological systems, the permeability

Vincent S. J. Craig; Chiara Neto; David R. M. Williams

2001-01-01

120

Downscaling of slip distribution for strong earthquakes  

NASA Astrophysics Data System (ADS)

We intend to develop a downscaling model to enhance the earthquake slip distribution resolution. Slip distributions have been obtained by other researchers using various inversion methods. As a downscaling model, we are discussing fractal models that include mono-fractal models (fractional Brownian motion, fBm; fractional Lévy motion, fLm) and multi-fractal models as candidates. Log - log-linearity of k (wave number) versus E (k) (power spectrum) is the necessary condition for fractality: the slip distribution is expected to satisfy log - log-linearity described above if we can apply fractal model to a slip distribution as a downscaling model. Therefore, we conducted spectrum analyses using slip distributions of 11 earthquakes as explained below. 1) Spectrum analyses using one-dimensional slip distributions (strike direction) were conducted. 2) Averaging of some results of power spectrum (dip direction) was conducted. Results show that, from the viewpoint of log - log-linearity, applying a fractal model to slip distributions can be inferred as valid. We adopt the filtering method after Lavallée (2008) to generate fBm/ fLm. In that method, generated white noises (random numbers) are filtered using a power law type filter (log - log-linearity of the spectrum). Lavallée (2008) described that Lévy white noise that generates fLm is more appropriate than the Gaussian white noise which generates fBm. In addition, if the 'alpha' parameter of the Lévy law, which governs the degree of attenuation of tails of the probability distribution, is 2.0, then the Lévy distribution is equivalent to the Gauss distribution. We analyzed slip distributions of 11 earthquakes: the Tohoku earthquake (Wei et al., 2011), Haiti earthquake (Sladen, 2010), Simeulue earthquake (Sladen, 2008), eastern Sichuan earthquake (Sladen, 2008), Peru earthquake (Konca, 2007), Tocopilla earthquake (Sladen, 2007), Kuril earthquake (Sladen, 2007), Benkulu earthquake (Konca, 2007), and southern Java earthquake (Konca, 2006)). We obtained the following results. 1) Log - log-linearity (slope of the linear relationship is ' - ?') of k versus E(k) holds for all earthquakes. 2) For example, ? = 3.70 and ? = 1.96 for the Tohoku earthquake (2011) and ? = 4.16 and ? = 2.00 for the Haiti earthquake (2010). For these cases, the Gauss' law is appropriate because alpha is almost 2.00. 3) However, ? = 5.25 and ? = 1.25 for the Peru earthquake (2007) and ? = 2.24 and ? = 1.57 for the Simeulue earthquake (2008). For these earthquakes, the Lévy law is more appropriate because ? is far from 2.0. 4) Although Lavallée (2003, 2008) concluded that the Lévy law is more appropriate than the Gauss' law for white noise, which is later filtered, our results show that the Gauss law is appropriate for some earthquakes. Lavallée and Archuleta, 2003, Stochastic modeling of slip spatial complexities for the 1979 Imperial Valley, California, earthquake, GEOPHYSICAL RESEARCH LETTERS, 30(5). Lavallée, 2008, On the random nature of earthquake source and ground motion: A unified theory, ADVANCES IN GEOPHYSICS, 50, Chap 16.

Yoshida, T.; Oya, S.; Kuzuha, Y.

2013-12-01

121

Coseismic slip, post-seismic slip, and largest aftershock associated with the 1994 Sanriku-haruka-oki, Japan, earthquake  

Microsoft Academic Search

We analyzed continuous GPS data to investigate the spatio-temporal distribution of co-seismic slip, post-seismic slip, and largest aftershock associated with the 1994 Sanriku-haruka-oki, Japan, earthquake (Mw = 7.7). To get better resolution for co-seismic and post-seismic slip distribution, we imposed a weak constraint as a priori information of the co-seismic slip determined by seismic wave analyses. We found that the

Yuji Yagi; Masayuki Kikuchi; Takuya Nishimura

2003-01-01

122

Threshold of Geomorphic Detectability Estimated from Geologic Observations of Active Slow-Slipping Strike-Slip Faults  

Microsoft Academic Search

Sources of catastrophic earthquakes include not only major active faults, but also slow-slipping ones. However, geomorphic characteristics and long-term seismic behavior of slow-slipping faults have not been well understood, although intensive paleoseismic studies were carried out after the unexpected 1992 Landers and 1999 Hector Mine earthquakes. Two Japanese surface faulting earthquakes on slow-slipping strike-slip faults (the 1927 Mw=7.0 Kita-Tango and

H. Kaneda

2002-01-01

123

Effects of slip, slip rate, and shear heating on the friction of granite  

USGS Publications Warehouse

The stability of fault slip is sensitive to the way in which frictional strength responds to changes in slip rate and in particular to the effective velocity dependence of steady state friction ????ss/?? ln V. This quantity can vary substantially with displacement, temperature and slip rate. To investigate the physical basis for this behavior and the possible influence of shear heating, we slid initially bare granite surfaces in unconfined rotary shear to displacements of hundreds of millimeters at normal stresses, ??n, of 10 and 25 MPa and at room temperature. We imposed step changes in slip rate within the range 10-2 to 103.5 ??m/s and also monitored frictional heating with thermistors embedded in the granite. The transient response of ?? to slip rate steps was fit to a rate- and state-dependent friction law using two state variables to estimate the values of several parameters in the constitutive law. The first 20 mm of slip shows rising friction and falling ????ss/?? ln V; further slip shows roughly constant friction, ????ss/?? ln V and parameter values, suggesting that a steady state condition is reached on the fault surface. At V ??? 10 ??m/s, ????ss/?? ln V = -0.004 ?? 0.001. At higher rates the response is sensitive to normal stress: At ??n = 25 MPa granite shows a transition to effective velocity strengthening (????ss/?? ln V = 0.008 ?? 0.004) at the highest slip rates tested. At 10 MPa granite shows a less dramatic change to ????ss/?? ln V ??? 0 at the highest rates. The maximum temperature measured in the granite is ???60??C at 25 MPa and 103.5 ??m/s. Temperatures are in general agreement with a numerical model of heat conduction which assumes spatially homogeneous frictional heating over the sliding surface. The simplest interpretation of our measurements of ????ss/?? ln V is that the granite is inherently veocity weakening (?????ss/??? In V 0 mimics velocity strengthening. These results have implications for the frictional behavior of faults during earthquakes. High slip rates may cause a switch to effective velocity strengthening which could limit peak coseismic slip rate and stress drop. For fluid-saturated faults, strengthening by this mechanism may be partly or fully offset by weakening due to thermal pressurization of a poorly drained pore fluid.

Blanpied, M. L.; Tullis, T. E.; Weeks, J. D.

1998-01-01

124

The Long Term Slip Deficit Budget and the Seismic Cycle.  

NASA Astrophysics Data System (ADS)

Estimates of spatially heterogeneous coupling between plates in subduction zones provide a basis for forecasting high slip in future events; strong coupling between earthquakes, producing rapid strain accumulation, should be correlated with high slip during the next earthquake. However, studies comparing coupling and slip do not show the expected correlation . We test the hypothesis that slip is governed, not only by coupling, but by the long term history of loading and slip on the fault; strongly coupled locations which have experienced large slip in recent earthquakes may have low slip-deficit, a measure of accumulated strain energy on the fault, despite their relatively high slip-deficit rate. Using reconstructions of slip in historical and recent earthquakes under the Mentawai Islands, W. Sumatra, we show that coupling is strongly correlated with slip accumulated over several events on the same segment rather than on any single earthquake. This observation is inconsistent with the idea of a characteristic earthquake and even of an earthquake cycle which together form the basis of of deterministic earthquake forecasting . Instead it suggests that slip-deficit is accumulated according to the plate convergence rate moderated by the strength of coupling and is relaxed heterogeneously during slip events which need show no repeatability either in time or in space; the slip deficit budget, at least for the Mentawai megathrust segment, needs balanced only over hundreds of years. This implies that slip-deficit estimated by reconstruction of slip and loading over long times, is necessary to understand the current state of stress on active faults.

McCloskey, John; Simao, Nuno; Lindsay, Tony; NicBhloscaidh, Mairead; Murphy, Shane; Natawidjaja, Danny; Nalbant, Suleyman

2013-04-01

125

Slip reactivation during the 2011 Tohoku earthquake: Dynamic rupture and ground motion simulations  

NASA Astrophysics Data System (ADS)

The 2011 Mw9 Tohoku earthquake generated such as vast geophysical data that allows studying with an unprecedented resolution the spatial-temporal evolution of the rupture process of a mega thrust event. Joint source inversion of teleseismic, near-source strong motion and coseismic geodetic data , e.g [Lee et. al, 2011], reveal an evidence of slip reactivation process at areas of very large slip. The slip of snapshots of this source model shows that after about 40 seconds the big patch above to the hypocenter experienced an additional push of the slip (reactivation) towards the trench. These two possible repeating slip exhibited by source inversions can create two waveform envelops well distinguished in the ground motion pattern. In fact seismograms of the KiK-Net Japanese network contained this pattern. For instance a seismic station around Miyagi (MYGH10) has two main wavefronts separated between them by 40 seconds. A possible physical mechanism to explain the slip reactivation could be a thermal pressurization process occurring in the fault zone. In fact, Kanamori & Heaton, (2000) proposed that for large earthquakes frictional melting and fluid pressurization can play a key role of the rupture dynamics of giant earthquakes. If fluid exists in a fault zone, an increase of temperature can rise up the pore pressure enough to significantly reduce the frictional strength. Therefore, during a large earthquake the areas of big slip persuading strong thermal pressurization may result in a second drop of the frictional strength after reaching a certain value of slip. Following this principle, we adopt for slip weakening friction law and prescribe a certain maximum slip after which the friction coefficient linearly drops down again. The implementation of this friction law has been done in the latest unstructured spectral element code SPECFEM3D, Peter et. al. (2012). The non-planar subduction interface has been taken into account and place on it a big asperity patch inside areas of big slip (>50m) close to the trench. Within the first 2km bellow the trench a negative stress drop has been imposed in order to represent the energy absorption zone that attenuates a high frequency radiation at the shallow part of the suduction zone. At down dip, where high frequency radiation burst has been detected from back projection techniques, e.g. [Meng et. al, 2011; Ishi , 2011], small asperities has been considered in our dynamic rupture model. Finally, a comparison of static geodetic free surface displacement and synthetics has been made to obtain our best model. We additionally compare seismograms with the aim to represent the main features of the strong ground motion recorded from this earthquake. Moreover, the spatial-temporal rupture evolution detected by back projection at down dip is in a good agreement with the rupture evolution of our dynamic model.

Galvez, P.; Dalguer, L. A.

2013-12-01

126

Equilibrium Statistics of Weakly Slip-Linked Gaussian Polymer Chains  

E-print Network

We calculate the free energy and the pressure of a weakly slip-linked Gaussian polymer chains. We show that the equilibrium statistics of a slip-linked system is different from one of the corresponding ideal chain system without any constraints by slip-links. It is shown that the pressure of a slip-linked system decreases compared with the ideal system, which implies that slip-linked chains spontaneously form aggregated cluster like compact structures. These are qualitatively consistent with previous theoretical analyses or multi chain simulations. We also show that repulsive potentials between chains, which have been phenomenologically utilized in simulations, can cancel the artificial pressure decrease.

Takashi Uneyama; Kazushi Horio

2011-04-15

127

Spatiotemporal evolution of seismic and aseismic slip on the Longitudinal Valley Fault, Taiwan  

NASA Astrophysics Data System (ADS)

The Longitudinal Valley Fault (LVF) in eastern Taiwan is a high slip rate fault (about 5 cm/yr), which exhibits both seismic and aseismic slip. Deformation of anthropogenic features shows that aseismic creep accounts for a significant fraction of fault slip near the surface, whereas a fraction of the slip is also seismic, since this fault has produced large earthquakes with five Mw>6.8 events in 1951 and 2003. In this study, we analyze a dense set of geodetic and seismological data around the LVF, including campaign mode Global Positioning System(GPS) measurements, time series of daily solutions for continuous GPS stations (cGPS), leveling data, and accelerometric records of the 2003 Chenkung earthquake. To enhance the spatial resolution provided by these data, we complement them with interferometric synthetic aperture radar (InSAR) measurements produced from a series of Advanced Land Observing Satellite images processed using a persistent scatterer technique. The combined data set covers the entire LVF and spans the period from 1992 to 2010. We invert this data to infer the temporal evolution of fault slip at depth using the Principal Component Analysis-based Inversion Method. This technique allows the joint inversion of diverse data, taking the advantage of the spatial resolution given by the InSAR measurements and the temporal resolution afforded by the cGPS data. We find that (1) seismic slip during the 2003 Chengkung earthquake occurred on a fault patch which had remained partially locked in the interseismic period, (2) the seismic rupture propagated partially into a zone of shallow aseismic interseismic creep but failed to reach the surface, and (3) that aseismic afterslip occurred around the area that ruptured seismically. We find consistency between geodetic and seismological constraints on the partitioning between seismic and aseismic creep. About 80-90% of slip on the southern section of LVF in the 0-26 km, seismogenic depth range, is actually aseismic. We infer that the clay-rich Lichi Mélange is the key factor promoting aseismic creep at shallow depth.

Thomas, Marion Y.; Avouac, Jean-Philippe; Champenois, Johann; Lee, Jian-Cheng; Kuo, Long-Chen

2014-06-01

128

Chondrolysis following slipped capital femoral epiphysis.  

PubMed

Medical records and radiographs of 17 known cases of slipped capital femoral epiphysis, treated with in-situ pin fixation and complicated by chondrolysis were reviewed. Fourteen of these 17 hips that developed chondrolysis had definite evidence of pin penetration of the femoral head. One hip had intra-articular pin penetration of the femoral neck. In the remaining two hips, the pins were placed within the anterolateral quadrant of the femoral head and within 2 mm of the articular surface. Overall, this is an 88% incidence of definite intra-articular pin penetration on postoperative radiographs, and a 100% rate if the two probable cases are included. This suggests a correlation between pin penetration and the development of chondrolysis following slipped capital femoral epiphysis. PMID:15091255

Jofe, Michael H; Lehman, Wallace; Ehrlich, Michael G

2004-01-01

129

Phase Slips in Oscillatory Hair Bundles  

NASA Astrophysics Data System (ADS)

Hair cells of the inner ear contain an active amplifier that allows them to detect extremely weak signals. As one of the manifestations of an active process, spontaneous oscillations arise in fluid immersed hair bundles of in vitro preparations of selected auditory and vestibular organs. We measure the phase-locking dynamics of oscillatory bundles exposed to low-amplitude sinusoidal signals, a transition that can be described by a saddle-node bifurcation on an invariant circle. The transition is characterized by the occurrence of phase slips, at a rate that is dependent on the amplitude and detuning of the applied drive. The resultant staircase structure in the phase of the oscillation can be described by the stochastic Adler equation, which reproduces the statistics of phase slip production.

Roongthumskul, Yuttana; Shlomovitz, Roie; Bruinsma, Robijn; Bozovic, Dolores

2013-04-01

130

Slip complexity in earthquake fault models.  

PubMed Central

We summarize studies of earthquake fault models that give rise to slip complexities like those in natural earthquakes. For models of smooth faults between elastically deformable continua, it is critical that the friction laws involve a characteristic distance for slip weakening or evolution of surface state. That results in a finite nucleation size, or coherent slip patch size, h*. Models of smooth faults, using numerical cell size properly small compared to h*, show periodic response or complex and apparently chaotic histories of large events but have not been found to show small event complexity like the self-similar (power law) Gutenberg-Richter frequency-size statistics. This conclusion is supported in the present paper by fully inertial elastodynamic modeling of earthquake sequences. In contrast, some models of locally heterogeneous faults with quasi-independent fault segments, represented approximately by simulations with cell size larger than h* so that the model becomes "inherently discrete," do show small event complexity of the Gutenberg-Richter type. Models based on classical friction laws without a weakening length scale or for which the numerical procedure imposes an abrupt strength drop at the onset of slip have h* = 0 and hence always fall into the inherently discrete class. We suggest that the small-event complexity that some such models show will not survive regularization of the constitutive description, by inclusion of an appropriate length scale leading to a finite h*, and a corresponding reduction of numerical grid size. Images Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:11607669

Rice, J R; Ben-Zion, Y

1996-01-01

131

Earthquake dynamics on dip-slip faults  

Microsoft Academic Search

Observations of dip-slip earthquakes have indicated that non-vertical geometry is associated with asymmetry in ground motion: thrust\\/reverse faults produce higher ground motion than normal faults, and hanging walls experience higher motion than footwalls. Using two- and three-dimensional computer simulations of fault dynamics, we show that these observations can be explained by the interaction between the free surface and the frictional

David D. Oglesby

1999-01-01

132

Earthquake slip on oceanic transform faults  

NASA Astrophysics Data System (ADS)

Oceanic transform faults are one of the main types of plate boundary, but the manner in which they slip remains poorly understood. Early studies suggested that relatively slow earthquake rupture might be common; moreover, it has been reported that very slow slip precedes some oceanic transform earthquakes, including the 1994 Romanche earthquake. The presence of such detectable precursors would have obvious implications for earthquake prediction. Here we model broadband seismograms of body waves to obtain well-resolved depths and rupture mechanisms for 14 earthquakes on the Romanche and Chain transform faults in the equatorial Atlantic Ocean. We found that earthquakes on the longer Romanche transform are systematically deeper than those on the neighbouring Chain transform. These depths indicate that the maximum depth of brittle failure is at a temperature of ~600°C in oceanic lithosphere. We find that the body waves from the Romanche 1994 earthquake can be well modelled with relatively deep slip on a single fault, and we use the mechanism and depth of this earthquake to recalculate its source spectrum. The previously reported slow precursor can be explained as an artefact of uncertainties in the assumed model parameters.

Abercrombie, Rachel E.; Ekström, Göran

2001-03-01

133

Earthquake slip on oceanic transform faults.  

PubMed

Oceanic transform faults are one of the main types of plate boundary, but the manner in which they slip remains poorly understood. Early studies suggested that relatively slow earthquake rupture might be common; moreover, it has been reported that very slow slip precedes some oceanic transform earthquakes, including the 1994 Romanche earthquake. The presence of such detectable precursors would have obvious implications for earthquake prediction. Here we model broadband seismograms of body waves to obtain well-resolved depths and rupture mechanisms for 14 earthquakes on the Romanche and Chain transform faults in the equatorial Atlantic Ocean. We found that earthquakes on the longer Romanche transform are systematically deeper than those on the neighbouring Chain transform. These depths indicate that the maximum depth of brittle failure is at a temperature of approximately 600 degrees C in oceanic lithosphere. We find that the body waves from the Romanche 1994 earthquake can be well modelled with relatively deep slip on a single fault, and we use the mechanism and depth of this earthquake to recalculate its source spectrum. The previously reported slow precursor can be explained as an artefact of uncertainties in the assumed model parameters. PMID:11242043

Abercrombie, R E; Ekström, G

2001-03-01

134

Source parameters and time-dependent slip distributions of slow slip events on the Cascadia subduction zone from 1998 to 2008  

Microsoft Academic Search

We invert for the time-dependent slip history of slow slip events on the Cascadia subduction zone using GPS data from 1998 to 2008. The 16 slip transients have sufficient station coverage to solve for the slip distribution on the plate interface. GPS time series are inverted for fault slip using the Extended Network Inversion Filter. Limited station coverage south of

D. A. Schmidt; H. Gao

2010-01-01

135

Modeling of rock friction 2. Simulation of preseismic slip  

USGS Publications Warehouse

The constitutive relations developed in the companion paper are used to model detailed observations of preseismic slip and the onset of unstable slip in biaxial laboratory experiments. The simulations employ a deterministic plane strain finite element model to represent the interactions both within the sliding blocks and between the blocks and the loading apparatus. Both experiments and simulations show that preseismic slip is controlled by initial inhomogeneity of shear stress along the sliding surface relative to the frictional strength. As a consequence of the inhomogeneity, stable slip begins at a point on the surface and the area of slip slowly expands as the external loading increases. A previously proposed correlation between accelerating rates of stable slip and growth of the area of slip is supported by the simulations. In the simulations and in the experiments, unstable slip occurs shortly after a propagating slip event traverses the sliding surface and breaks out at the ends of the sample. In the model the breakout of stable slip causes a sudden acceleration of slip rates. Because of velocity dependency of the constitutive relationship for friction, the rapid acceleration of slip causes a decrease in frictional strength. Instability occurs when the frictional strength decreases with displacement at a rate that exceeds the intrinsic unloading characteristics of the sample and test machine. A simple slider-spring model that does not consider preseismic slip appears to approximate the transition adequately from stable sliding to unstable slip as a function of normal stress, machine stiffness, and surface roughness for small samples. However, for large samples and for natural faults the simulations suggest that the simple model may be inaccurate because it does not take into account potentially large preseismic displacements that will alter the friction parameters prior to instability. Copyright ?? 1979 by the American Geophysical Union.

Dieterich, J.H.

1979-01-01

136

Coseismic slip on shallow décollement megathrusts  

NASA Astrophysics Data System (ADS)

Many regions of plate convergence are underlain by décollement megathrusts, which form the base of both accretionary wedges and fold-and-thrust belts. These faults may extend laterally for hundreds or thousands of kilometers, and downdip for tens to hundreds of kilometers. Traditionally, estimates of seismic hazard have assumed that these faults slip aseismically, without releasing significant seismic energy, under the belief that they are too weak to build accumulate large stresses. However, in several recent cases, these faults have been shown to slip in large, discrete events, resulting in hazardous groundshaking and/or tsunamis (e.g., 2011 Tohoku-Oki earthquake, Japan; 2010 Mentawai earthquake, Indonesia; 1999 Chi-Chi earthquake, Taiwan). We present a series of fifteen examples, both on-land and offshore, demonstrating that many shallow dé- collements are capable of producing large, coseismic slip events that rupture to the toes of the systems. Some of these events are associated with ruptures that initiate down-dip, while others are limited to the frontal, shallow portion of the wedge, illustrating that the frontal portion can initiate rupture as well as participate in ruptures that initiated elsewhere. We suggest that this behavior is not limited to the examples described here, but rather is common to many (perhaps most) accretionary wedges and fold-and-thrust belts. Although many earthquakes in subduction zones have been interpreted to have no slip at the tip of the accretionary prism, this interpretation is typically driven by model assumptions, rather than the data. We suggest that in addition to the examples provided here, there may be many other examples of similar earthquakes, where existing data cannot constrain slip at the toe. We do not characterize the regions and events described here as unusual, as they encompass a wide range of settings. This study indicates that there is an urgent need to reevaluate seismic and tsunami hazard in fold-and-thrust belts and subduction zones around the world, allowing for the possibility of shallow décollement rupture.

Hubbard, Judith; Barbot, Sylvain; Hill, Emma M.; Tapponnier, Paul

2014-05-01

137

Long-term slip deficit and the forecasting of slip in future earthquakes  

NASA Astrophysics Data System (ADS)

In the last decade a series of devastating earthquakes have between them killed more than three-quarters of a million people. None of the events were formally forecast and have been repeatedly referred to a seismological 'surprises'. Here we argue that while earthquakes within the wide swath of diffuse deformation comprising the Alpine-Himalayan belt pose a set of particularly difficult set of challenges, earthquakes which are driven by high strain-rates at plate boundaries and which have relatively short nominal recurrence times might be forecast if the data exists to perform long-term slip deficit modelling and stress reconstruction. We show that two instrumentally recorded event on the Sumatran margin in 2007 and 2010 occurred in regions of high slip deficit identified by reconstruction of slip in historical earthquakes in 1797 and 1833 under the Mentawai Islands using more than 200 years of geodetic data recorded in the stratigraphy of coral micro-atolls growing there. In the presentation we will describe the data and a new Bayesian-Monte Carlo slip reconstruction technique. The technique is based on the stochastic forward modelling of many slip distributions each using the same set of elastic Green's functions to estimate, by superposition of contributions from each fault cell, the vertical displacement at the coral locations resulting from each simulated event. Every solution, weighted by its goodness of fit to the data, is added to a stack whose final values contain an estimate of the most likely distribution of slip in the historical earthquakes. Further, we estimate the Kullback-Liebler divergence over the fault area providing a non-arbitrary assessment of the spatial distribution of information gain, identifying regions of low- and high- model confidence. We then model the long-term slip deficit on the megathrust assuming a zero of stress immediately after the 1652 Mentawai Islands earthquake. We use the resulting slip deficit field to compute the entire stress field including both secular loading and earthquake interaction stresses. We show that the spatial distribution of energy release in the 2007 and 2010 earthquakes correlates strongly with regions of high slip deficit accumulated over the previous 350 years and that in principle both could have been identified as areas of particularly high seismic hazard. The following more general seismological lessons emerge from our work: 1 At least for this region of this margin, the characteristic earthquake concept entirely fails to explain the data 2 Earthquake slip tessellates the fault plane under the Mentawai Islands rather than repeatedly breaking the same patch. 3 The tessellation by high slip is largely constrained by the interface coupling distribution (which, of course, played no part in the slip reconstruction). 4 Homogeneous loading of a heterogeneous fault in a linear-elastic medium explains all the observations, no rheological time dependence is necessary. 5 Even small amounts of nonlinearity in the rupture process would ensure that this sequence will not be repeated, calling into question many long-standing, fundamental concepts in earthquake science.

McCloskey, John; NicBhloscaidh, Mairead; Simao, Nuno

2014-05-01

138

Quasi-static versus dynamic triggering of fault slip  

NASA Astrophysics Data System (ADS)

The quasi-static triggering of fault slip has long been recognized as a mechanism of earthquakes. The dynamic triggering of fault slip is associated with earthquake aftershocks and man-made geological hazards, such as rock collapse in underground excavations and induced seismicity in geothermal productions. The objective of this study is to experimentally investigate the differences between quasi-static and dynamic triggering of fault slip. A direct-shear configuration (Fig. 1) is developed to simulate fault slip, which consists of an incident norite plate (1000 × 120 × 30 mm) and a transverse norite plate (500 × 80 × 30 mm). A quartz sand layer is sandwiched between the incident and transverse plates to simulate a granular fault zone. A servo-controlled quasi-static loading system induces the quasi-static triggering of fault slip, and a dynamic loading system containing two parallel compressed springs instantaneously launches a striker norite plate (100 × 120 × 30 mm) to induce an incident P-wave (a half-wavelength of 750 mm). The P-wave propagates in the incident plate and causes the dynamic triggering of fault slip. The dynamic triggering of fault slip is designed to be solely induced by the P-wave before wave reflection at the plate end. Both quasi-static and dynamic triggering induce non-uniform shear stress distribution along the fault zone. There is a shear stress at the trailing edge, which controls the fault slip, and a rebound stress at the leading edge, which is caused by a small moment. The fault slip is triggered when the maximum shear stress reaches a critical value at the trailing edge and is accompanied by shear stress drop. The quasi-static triggering of fault slip is unrecoverable and includes a main slip and a few short slips before and after the main slip. The dynamic triggering of fault slip can be partially recovered after the P-wave and consists of a few unrecovered slips. The duration of the dynamic triggering of fault slip is a few microseconds, while the duration of the quasi-static triggering is from a few seconds to many years. Fault strengthening takes a long time between slips. However, seismic waves may successively induce fault slip and restrict fault self-healing. Fig. 1 Schematic diagram of the direct-shear configuration.

Wu, W.

2013-12-01

139

Great Earthquakes With and Without Large Slip to the Trench  

NASA Astrophysics Data System (ADS)

The 2011 Tohoku-oki earthquake produced a huge amount of slip (40 to 60 meters) on the shallow portion of the subduction zone close to the trench. This large displacement was largely unexpected for this region and caused the very large and damaging tsunami along the northeast coast of Honshu. For other subduction zones around the world, we examine the possibility of large slip to the trench in past large and great earthquakes. Since the trench region is generally far offshore, it is often difficult to resolve the amount of slip from onland geodetic and strong-motion data. We use a variety of observations, including slip distribution models, aftershock locations, local coastal deformation, and tsunami heights to determine which events likely had large amounts of slip close to the trench. Tsunami earthquakes, such as 1992 Nicaragua and 2006 Java likely had large shallow slip. Some typical subduction earthquakes, such as 1968 Tokachi-oki and 2003 Tokachi-oki (located in regions north of the source area of the 2011 Tohoku-oki earthquake) likely did not. We will discuss possible factors that influence the slip distribution on the shallow area of subduction megathrusts. Using results from the Japan Trench Fast Drilling Project (JFAST) which sampled the fault in the region of large slip, we can begin to understand the conditions of very large fault slip. Are there characteristic features in the material properties for faults that have large slip ? Can we determine if these regions have high plate coupling and accumulate stress ?

Mori, J. J.

2013-12-01

140

Particles in Creeping Flow Near a Slip Wall  

NASA Astrophysics Data System (ADS)

The no-slip boundary condition on a wall is the classical one for a viscous flow. But it has been recently recognized that a slip can take place at small scales, e.g., on hydrophobic surfaces. Slip is characterized by a slip length, that is the distance at which a fictitious no-slip plane is moved away from the fluid to represent the slip plane in a shear flow. The slip length may be measured by following the motion of nanosized spheres close to such a surface. The motion of particles close to a slip surface also has applications in microfluidics, separation techniques in analytical chemistry, etc. With these applications in view, this paper considers a spherical solid particle in creeping flow close to a slip wall. The flow along the wall is locally approximated by a pure shear flow and the sphere is translating and rotating. The various perturbed flow fields around the sphere are solved analytically using the bispherical coordinates technique. The hydrodynamic force and torque on the sphere are obtained in terms of the slip length. Results are provided with a precision better than 10-7, even for a small gap down to 10-4 sphere radius. The translational and rotational velocities of a freely moving sphere in a pure shear flow near a slip wall are then calculated. The hindered Brownian diffusion of a freely rotating sphere close to a slip wall is characterized by a diffusion tensor, the coefficients of which are derived. Finally, the Aris-Taylor dispersion of Brownian particles in a shear flow near a slip wall is calculated from the advection-diffusion equation, using the expression for the particle velocity. For this purpose, the equation is first Fourier-transformed in the direction of vorticity. The transformed two-dimensional equation is solved by a finite elements package using a refined mesh.

Feuillebois, F.; Loussaief, H.; Pasol, L.

2009-10-01

141

Joint Sealants for Horizontal Pavement Joints—Specifically Bridge Joints  

Microsoft Academic Search

The various types of materials that have been used to seal bridge joints have been reviewed. Some of the bridge engineers joint material requirements have been listed together with the advantages and disadvantages of the three most widely used bridge joint sealants being specified and used today. It is felt that the cold applied two component asphalt-modified polyurethane sealants come

Thomas J. Green

1969-01-01

142

Complicated Recurrence of Slip Events on a Uniform Circular Asperity  

NASA Astrophysics Data System (ADS)

Numerical simulation of repeated occurrence of slip events on a fault patch (asperity) is conducted to understand the mechanism of irregularity of the events. Seismic and geodetic observations indicate that episodic seismic/aseismic slip events repeatedly occur at almost the same area. For instance, magnitude of about 4.8 earthquakes had repeatedly occurred at intervals of 4.7 to 6.7 years off Kamaishi, northern Honshu, Japan. Quasi-periodic recurrence of episodic aseismic slip events (slow earthquakes) was found at the Nankai subduction zone, southwestern Japan, the Cascadia subduction zone, North America, etc. The recurrence intervals and magnitudes of slip events in each sequence are not constant, but some variability exists. Some researchers suggested that the variation in aseismic slip rate around a patch of slip events causes variation of loading rate. This results in variation of recurrence intervals. In the present study, we focus on irregularity of recurrence of slip events that originates from dynamics of fault slip. A two-dimensional planar fault in an infinite elastic medium is considered. The fault is uniformly shear loaded at a constant rate, and frictional stress acting on the fault is assumed to obey a rate- and state-dependent friction (RSF) law. A circular patch of radius r with velocity-weakening frictional property is embedded on a fault with velocity-strengthening frictional property elsewhere. A numerical simulation is conducted by varying the characteristic slip distance L of the RSF law. The critical radius rc for occurrence of unstable slip can be defined, and rc is proportional to L. When r >> rc, seismic slip events (earthquakes) repeatedly occur at a constant time interval. When r is a little larger than rc, recurrence of slip events becomes complex. We observe a period-2 cycle of slip events, where large and small events alternately occur. The cycle becomes more complex as r approaches rc and finally aperiodic (chaotic) slip pattern occurs. During the increase of slip complexity, a period-doubling sequence is observed. An iteration map of recurrence intervals of slip events is examined by taking a plot of Ti versus Ti-1, where Ti denotes the time interval between the ith and (i+1)th slip events. The iteration map is expressed by a simple curve, suggestive of predictability of the occurrence time of the next event from the previous time interval. To understand the cause of the variation of slip events, the distributions of shear stress on the fault before the slip events are examined. We observe a large variation of the shear stress distribution within the velocity-weakening region, which is generated by the preceding slip event and aseismic sliding during an interseismic period. To compare the simulation result of sequence of slip events on a velocity-weakening patch embedded in velocity-strengthening region, a numerical simulation of slip on a velocity-weakening patch enclosed by unbreakable barrier. In this case, no complex recurrence of slip events is observed. When r > rc, seismic slip events repeatedly occur at a constant interval. On the other hand, stable sliding occurs when r < rc. This result indicates that the complicated slip behavior for a velocity-weakening patch embedded in velocity-strengthening region comes from the interaction between the velocity-weakening and velocity-strengthening regions.

Kato, N.

2012-12-01

143

Physical modeling of deformation patterns in monoclines above oblique-slip faults  

NASA Astrophysics Data System (ADS)

Many basement-involved fault-related folds are thought to form by reactivation of pre-existing faults. Although oblique slip is expected on such structures it is often difficult to identify because the underlying faults are blind, paleomagnetic records are ambiguous, and mesoscopic deformation patterns in the associated monoclines are often incompletely exposed or difficult to interpret. This study seeks to establish a relationship between oblique slip on a basement reverse fault and the deformation patterns in the overlying folded rock layers. Using scaled physical models of wet clay overlying a rigid basement, we create a suite of Laramide-style folds over basement faults with variable obliquity. Precise displacements and strains on the surface of the clay are recorded using close-range photogrammetry. We use these measurements to predict deformation patterns that we would expect to find in analogous natural structures. The results of our models show that there are three general strain zones that form in monoclines that form above oblique-slip faults. The upper-hinge region of the monocline is dominated by extension, the lower-hinge region by contraction, and the middle of the fold limb is dominated by shear strains. The boundaries of these three zones, as well as the magnitude of strain in each of the zones vary with the amount of oblique slip and fault throw. Deformation should be dominated by joints and extensional faults in the extensional zone, by contractional faults and cleavage in the contractional zone, and may contain extensional, contractional, or strike-slip faults along with joints and cleavage arranged in Riedel style geometries in the shear strain dominated zone. At fault obliquities above 45° there is significant overlap of the different strain zones and deformation patterns in these regions can consequently be very complex, involving reactivation or overprinting of earlier structures, or the formation of mixed-mode structures. Displacements on the surface of our model monoclines suggest that previous paleomagnetic interpretations of vertical axis rotations on natural monoclines may need to be re-evaluated. Although such rotations increase with increasing fault obliquity, the magnitude of these rotations will vary significantly with position across a monocline.

Keating, David P.; Fischer, Mark P.; Blau, Harvey

2012-06-01

144

Geodetic slip rates in the southern San Andreas Fault system: Investigation of the effects of heterogeneous elastic structure  

NASA Astrophysics Data System (ADS)

We investigate the importance of fault geometry and crustal heterogeneity on estimates of slip rates and locking depths of the Southern San Andreas fault (SAF) and San Jacinto fault (SJF). Previous estimates of geodetic slip rates in the Salton Sea region based on dislocation models have generally inferred a higher slip rate on the SAF (21-26 mm/yr) compared to the SJF (12-19 mm/yr). The inferred geodetic slip rate on the SAF is higher than recent geologic estimates representing average slip rates on time scales of 10^4-10^6 years. We investigate to what extent the geodetically inferred slip rate might be biased by incorrect assumptions about the fault geometry and neglect of spatial variations in crustal rigidity. To address this issue, we use a forward model that incorporates heterogeneous elastic moduli computed from the SCEC CVM-H seismic tomography model of Southern California. In our inversions we allow for a non-vertical SAF and a "blind" segment of the SJF, the previously suggested southern continuation of the Clark fault. The models are compared to surface velocities derived from a combination of all available continuous and campaign GPS sites in the region, processed in a consistent North American fixed frame (NAFD), and InSAR data spanning 18 years (1992-2010). These data sources are strongly complementary: while InSAR provides higher spatial resolution in the near-fault region, we find that GPS sites located more than 10 locking depths from the fault are required to resolve the trade-off between locking depth and fault slip rate. The parameter space is examined using an efficient Monte Carlo algorithm which approximates the joint probability distribution for the model parameters and allows for a formal evaluation of uncertainties and trade-offs. We estimate slip rates of 15(+/-2) mm/yr for the Southern San Andreas fault and a total of 23(+/-3) mm/yr for the two closely spaced branches of the southern San Jacinto fault, in reasonable agreement with geologic estimates. The locking depths are estimated at 9(+/-3) km and 16(+/-3) km for the SAF and SJF, respectively. The incorporation of realistic elastic properties serves to increase the estimated locking depths on both faults by 2-3 km, and decreases the estimated slip rate on the San Andreas fault by several mm/yr in comparison to a homogeneous elastic model.

Lindsey, E. O.; Fialko, Y.

2011-12-01

145

Multiplate magnetorheological fluid limited slip differential clutch  

NASA Astrophysics Data System (ADS)

This study focuses on the design and characterization of a multi-plate magneto-rheological fluid (MRF) limited slip differential (LSD) clutch. Three-dimensional electromagnetic finite element analyzes are performed to optimize the MRF LSD clutch design. The torque transfer capacity of the clutch is predicted utilizing Bingham-Plastic constitutive model of the MRF. The MRF LSD clutch is tested at different velocities and applied magnetic fields. The clutch heating is also examined under different operating conditions to determine the thermal effects on the torque transfer performance of the multi-plate clutch.

Kavlicoglu, Barkan M.; Gordaninejad, Faramarz; Evrensel, Cahit A.; Fuchs, Alan; Korol, George

2003-08-01

146

Slip control for LIM propelled transit vehicles  

NASA Astrophysics Data System (ADS)

Short stator linear induction motors, with an iron-backed aluminum sheet reaction rail and powered by a controlled inverter, have been selected as the propulsion system for transit vehicles in an intermediate capacity system (12-20,000 pphpd). The linear induction motor is capable of adhesion independent braking and acceleration levels which permit safe, close headways. In addition, simple control is possible allowing moving block automatic train control. This paper presents a slip frequency control scheme for the LIM. Experimental results for motoring and braking obtained from a test vehicle are also presented. These values are compared with theoretical predictions.

Wallace, A. K.; Parker, J. H.; Dawson, G. E.

1980-09-01

147

Microfluidics: The no-slip boundary condition  

E-print Network

The no-slip boundary condition at a solid-liquid interface is at the center of our understanding of fluid mechanics. However, this condition is an assumption that cannot be derived from first principles and could, in theory, be violated. We present a review of recent experimental, numerical and theoretical investigations on the subject. The physical picture that emerges is that of a complex behavior at a liquid/solid interface, involving an interplay of many physico-chemical parameters, including wetting, shear rate, pressure, surface charge, surface roughness, impurities and dissolved gas.

Eric Lauga; Michael P. Brenner; Howard A. Stone

2005-01-24

148

Stick-slip friction and energy dissipation in boundary lubrication.  

PubMed

Shearing of a simple nonpolar film, right after the liquid-to-solid phase transition under nanometer confinement, is studied by using a liquid-vapor molecular dynamics simulation method. We find that, in contrast with the shear melting and recrystallization behavior of the solidlike phase during the stick-slip motion, interlayer slips within the film and wall slips at the wall-film interface are often observed. The ordered solidified film is well maintained during the slip. Through the time variations of the frictional force and potential energy change within the film, we find that both the friction dissipation during the slip and the potential energy decay after the slip in the solidified film take a fairly large portion of the total energy dissipation. PMID:22107235

Lei, Yajie; Leng, Yongsheng

2011-09-30

149

Crystal plasticity finite element analysis of deformation behaviour in SAC305 solder joint  

NASA Astrophysics Data System (ADS)

Due to the awareness of the potential health hazards associated with the toxicity of lead (Pb), actions have been taken to eliminate or reduce the use of Pb in consumer products. Among those, tin (Sn) solders have been used for the assembly of electronic systems. Anisotropy is of significant importance in all structural metals, but this characteristic is unusually strong in Sn, making Sn based solder joints one of the best examples of the influence of anisotropy. The effect of anisotropy arising from the crystal structure of tin and large grain microstructure on the microstructure and the evolution of constitutive responses of microscale SAC305 solder joints is investigated. Insights into the effects of key microstructural features and dominant plastic deformation mechanisms influencing the measured relative activity of slip systems in SAC305 are obtained from a combination of optical microscopy, orientation imaging microscopy (OIM), slip plane trace analysis and crystal plasticity finite element (CPFE) modeling. Package level SAC305 specimens were subjected to shear deformation in sequential steps and characterized using optical microscopy and OIM to identify the activity of slip systems. X-ray micro Laue diffraction and high energy monochromatic X-ray beam were employed to characterize the joint scale tensile samples to provide necessary information to be able to compare and validate the CPFE model. A CPFE model was developed that can account for relative ease of activating slip systems in SAC305 solder based upon the statistical estimation based on correlation between the critical resolved shear stress and the probability of activating various slip systems. The results from simulations show that the CPFE model developed using the statistical analysis of activity of slip system not only can satisfy the requirements associated with kinematic of plastic deformation in crystal coordinate systems (activity of slip systems) and global coordinate system (shape changes) but also this model is able to predict the evolution of stress in joint level SAC305 sample.

Darbandi, Payam

150

Coseismic slip distribution of the 1946 Nankai earthquake and aseismic slips caused by the earthquake  

Microsoft Academic Search

Coseismic slip distribution on the fault plane of the 1946 Nankai earthquake (Mw 8.3) was estimated from inversion of tsunami waveforms. The following three improvements from the previous study (Satake, 1993) were made. (1) Larger number of smaller subfaults is used; (2) the subfaults fit better to the slab geometry; and (3) more detailed bathymetry data are used. The inversion

Yuichiro Tanioka; Kenji Satake

2001-01-01

151

Investigating the origins of observed variability of slow slip events with fault slip simulations  

NASA Astrophysics Data System (ADS)

Slow slip events (SSEs) in subduction zones around the world exhibit a wide range of recurrence intervals, durations, and spatial extents. In some regions, most notably Cascadia, distinct along-strike segmentation of these SSE characteristics have been observed. Yet the temporal extent of the SSE record is insufficient to determine whether along-strike variation in segmentation of SSEs persists beyond human time-scales. Here we employ the earthquake simulator RSQSim to model a simple, planar megathrust, which consists of seismogenic, slow slip, and continuous creep sections. The slow slip section is segmented to explore potential causes of along-strike variability in recurrence intervals, durations, and spatial extent, by varying parameters such as the effective normal stress, frictional properties, slip rates, and fault geometry. RSQSim enables simulations of long histories of SSEs over all orders of magnitude to allow for robust characterization of the variation in parameters. Preliminary results suggest even small variations in these parameters have a significant effect on observable characteristics of SSEs, which may illuminate the primary controls on along-strike variability and help establish a framework for understanding SSEs worldwide.

Watkins, W. D.; Colella, H.; Brudzinski, M. R.; Dieterich, J. H.; Richards-Dinger, K. B.

2013-12-01

152

Identification of maximum road friction coefficient and optimal slip ratio based on road type recognition  

NASA Astrophysics Data System (ADS)

The identification of maximum road friction coefficient and optimal slip ratio is crucial to vehicle dynamics and control. However, it is always not easy to identify the maximum road friction coefficient with high robustness and good adaptability to various vehicle operating conditions. The existing investigations on robust identification of maximum road friction coefficient are unsatisfactory. In this paper, an identification approach based on road type recognition is proposed for the robust identification of maximum road friction coefficient and optimal slip ratio. The instantaneous road friction coefficient is estimated through the recursive least square with a forgetting factor method based on the single wheel model, and the estimated road friction coefficient and slip ratio are grouped in a set of samples in a small time interval before the current time, which are updated with time progressing. The current road type is recognized by comparing the samples of the estimated road friction coefficient with the standard road friction coefficient of each typical road, and the minimum statistical error is used as the recognition principle to improve identification robustness. Once the road type is recognized, the maximum road friction coefficient and optimal slip ratio are determined. The numerical simulation tests are conducted on two typical road friction conditions(single-friction and joint-friction) by using CarSim software. The test results show that there is little identification error between the identified maximum road friction coefficient and the pre-set value in CarSim. The proposed identification method has good robustness performance to external disturbances and good adaptability to various vehicle operating conditions and road variations, and the identification results can be used for the adjustment of vehicle active safety control strategies.

Guan, Hsin; Wang, Bo; Lu, Pingping; Xu, Liang

2014-08-01

153

A treatment algorithm for stable slipped capital femoral epiphysis deformity.  

PubMed

The authors' current experience in the surgical treatment strategy of stable slipped capital femoral epiphysis deformities was reviewed. From this, a treatment algorithm was developed that could be utilized as a guide in the evaluation and treatment of future patients with slipped capital femoral epiphysis. The clinical parameters of patients' histories of symptoms, physical examinations, and radiographic assessments of slip severity were used in formulating the algorithm. The intent was to prepare a comprehensive algorithm providing necessary alternate treatment pathways for the variable slip deformity in accordance with the surgical experience/expertise of the treating surgeon. PMID:23764781

Schoenecker, Perry L; Gordon, J Eric; Luhmann, Scott J; Dobbs, Matthew B; Keeler, Kathryn A; Clohisy, John C

2013-01-01

154

Slip and flow of hard-sphere colloidal glasses  

E-print Network

We study the flow of concentrated hard-sphere colloidal suspensions along smooth, non-stick walls using cone-plate rheometry and simultaneous confocal microscopy. In the glass regime, the global flow shows a transition from Herschel-Bulkley behavior at large shear rate to a characteristic Bingham slip response at small rates, absent for ergodic colloidal fluids. Imaging reveals both the `solid' microstructure during full slip and the local nature of the `slip to shear' transition. Both the local and global flow are described by a phenomenological model, and the associated Bingham slip parameters exhibit characteristic scaling with size and concentration of the hard spheres.

P. Ballesta; R. Besseling; L. Isa; G. Petekidis; W. C. K. Poon

2008-07-09

155

Strong dynamical effects during stick-slip adhesive peeling.  

PubMed

We consider the classical problem of the stick-slip dynamics observed when peeling a roller adhesive tape at a constant velocity. From fast imaging recordings, we extract the dependence of the stick and slip phase durations on the imposed peeling velocity and peeled ribbon length. Predictions of Maugis and Barquins [in Adhesion 12, edited by K. W. Allen, Elsevier ASP, London, 1988, pp. 205-222] based on a quasistatic assumption succeed to describe quantitatively our measurements of the stick phase duration. Such a model however fails to predict the full stick-slip cycle duration, revealing strong dynamical effects during the slip phase. PMID:24651387

Dalbe, Marie-Julie; Santucci, Stéphane; Cortet, Pierre-Philippe; Vanel, Loïc

2014-01-01

156

Strong dynamical effects during stick-slip adhesive peeling  

NASA Astrophysics Data System (ADS)

We consider the classical problem of the stick-slip dynamics observed when peeling a roller adhesive tape at a constant velocity. From fast imaging recordings, we extract the dependencies of the stick and slip phases durations with the imposed peeling velocity and peeled ribbon length. Predictions of Maugis and Barquins [in Adhesion 12, edited by K.W. Allen, Elsevier ASP, London, 1988, pp. 205--222] based on a quasistatic assumption succeed to describe quantitatively our measurements of the stick phase duration. Such model however fails to predict the full stick-slip cycle duration, revealing strong dynamical effects during the slip phase.

Dalbe, Marie-Julie; Santucci, Stéphane; Cortet, Pierre-Philippe; Vanel, Loïc

157

Frictional slip of granite at hydrothermal conditions  

USGS Publications Warehouse

To measure the strength, sliding behavior, and friction constitutive properties of faults at hydrothermal conditions, laboratory granite faults containing a layer of granite powder (simulated gouge) were slid. The mechanical results define two regimes. The first regime includes dry granite up to at least 845?? and wet granite below 250??C. In this regime the coefficient of friction is high (?? = 0.7 to 0.8) and depends only modestly on temperature, slip rate, and PH2O. The second regime includes wet granite above ~350??C. In this regime friction decreases considerably with increasing temperature (temperature weakening) and with decreasing slip rate (velocity strengthening). These regimes correspond well to those identified in sliding tests on ultrafine quartz. The results highlight the importance of fluid-assisted deformation processes active in faults at depth and the need for laboratory studies on the roles of additional factors such as fluid chemistry, large displacements, higher concentrations of phyllosilicates, and time-dependent fault healing. -from Authors

Blanpied, M.L.; Lockner, D.A.; Byerlee, J.D.

1995-01-01

158

Spacesuit mobility joints  

NASA Technical Reports Server (NTRS)

Joints for use in interconnecting adjacent segments of an hermetically sealed spacesuit which have low torques, low leakage and a high degree of reliability are described. Each of the joints is a special purpose joint characterized by substantially constant volume and low torque characteristics. Linkages which restrain the joint from longitudinal distension and a flexible, substantially impermeable diaphragm of tubular configuration spanning the distance between pivotally supported annuli are featured. The diaphragms of selected joints include rolling convolutions for balancing the joints, while various joints include wedge-shaped sections which enhance the range of motion for the joints.

Vykukal, H. C. (inventor)

1978-01-01

159

Spacesuit mobility knee joints  

NASA Technical Reports Server (NTRS)

Pressure suit mobility joints are for use in interconnecting adjacent segments of an hermetically sealed spacesuit in which low torques, low leakage and a high degree of reliability are required. Each of the joints is a special purpose joint characterized by substantially constant volume and low torque characteristics and includes linkages which restrain the joint from longitudinal distension and includes a flexible, substantially impermeable diaphragm of tubular configuration spanning the distance between pivotally supported annuli. The diaphragms of selected joints include rolling convolutions for balancing the joints, while various joints include wedge-shaped sections which enhance the range of motion for the joints.

Vykukal, H. C. (inventor)

1979-01-01

160

Damage zones around strike-slip fault systems and strike-slip fault evolution, Crackington Haven, southwest England  

Microsoft Academic Search

A well exposed outcrop of Upper Carboniferous greywackes and slates at Crackington Haven, north Cornwall, shows several episodes\\u000a of strike-slip faulting. Exposure-scale structures display may features typical of strike-slip fault systems including: splay\\u000a faults, wing cracks, jogs, fault bends, fault branches, ? faults, rotated blocks, together with layer-parallel slip, and deformation\\u000a of the wall-rocks.\\u000a \\u000a The strike-slip faults developed with a

Young-Seog Kim; Jim R. Andrews; David J. Sanderson

2000-01-01

161

Dilatant strengthening as a mechanism for slow slip events  

NASA Astrophysics Data System (ADS)

The mechanics of slow slip events (SSE) in subduction zones remain unresolved. We suggest that SSE nucleate in areas of unstable friction under drained conditions, but as slip accelerates dilatancy reduces pore pressure p quenching instability. Competition between dilatant strengthening and thermal pressurization may control whether slip is slow or fast. We model SSE with 2-D elasticity, rate-state friction, and a dilatancy law where porosity ? evolves toward steady state ?ss over distance dc and ?ss = ?0 + ? ln(v/v0); v is slip speed. We consider two diffusion models. Membrane diffusion (MD) is approximated by -(p - p?)/tf where p and p? are shear zone and remote pore pressure and tf is a characteristic diffusion time. Homogeneous diffusion (HD) accurately models fault-normal flow with diffusivity chyd. For MD, linearized analysis defines a boundary ? = 1 - a/b between slow and fast slip, where ? ? f0?/?b(? - p?), f0, a, and b are friction parameters and ? is compressibility. When ? < 1 - a/b slip accelerates to instability for sufficiently large faults, whereas for ? > 1 - a/b slip speeds remain quasi-static. For HD, Ep ? ?h/(? (? - p?)?) defines dilatancy efficiency, where h is shear zone thickness and v? is plate velocity. SSE are favored by large ?h and low effective stress. The ratio Ep to thermal pressurization efficiency scales with 1/(? - p?), so high p? favors SSE, consistent with seismic observations. For Ep ˜ 10-3 transient slip rates, repeat times, average slip, and stress drops are comparable to field observations. Model updip propagation speeds are comparable to those observed along-strike. Many simulations exhibit slow phases driven by steady downdip slip and faster phases that relax the accumulated stress. Model SSE accommodate only a fraction of plate motion; the remaining deficit must be accommodated during coseismic or postseismic slip.

Segall, Paul; Rubin, Allan M.; Bradley, Andrew M.; Rice, James R.

2010-12-01

162

Slip velocity dependence on shear-induced permeability evolution  

NASA Astrophysics Data System (ADS)

Evolution of fluid transport properties of a fault zone during seismic slip can influence on the dynamic fault process in a subducing plate boundary, though permeability change caused by dynamic slip motion is less well documented. In this study, we measured water permeability and seismic velocity for high porosity sandstone (Berea sandstone, porosity = 20%), low porosity sandstone (Indian sandstone, 11~14 %) and granite (Aji granite, 0.5 %) after shear deformation at various slip rates from 0.1 to 1300 mm/s in laboratory experiments. Friction tests were performed at low normal stress from 1 to 2MPa and below 10 m of slip displacement. Permeability of Berea sandstone decreases by one order of magnitude with increase in slip rate and slip displacement. Permeability of Indian sandstone and Aji granite increases dramatically by three orders of magnitude at high slip rate above 300 mm/s. Fine grained gouges are developed along simulated slip surface in all rock specimens, and the width of gouge layers are proportional to slip rate and slip displacement. Microcracks and mesoscale fractures are nucleated in specimens at 1300 mm/s of slip velocity. Temperature distribution of specimen in friction experiments estimated by finite element method using laboratory data shows temperature on a slip surface rises several hundred degrees above 130 mm/s of slip velocity, and temperature would have exceeded ?-? phase transition temperature of quartz at 1300 mm/s of slip velocity. The thermal gradient along the axis normal to slip surface is very sweep at high slip rate. Permeability reduction in porous sandstone after friction test is explained by the growth of the finer grained gouge layer, which is less permeable than that of host rocks. A sudden permeability increase for low porosity sandstone and granite is explained by the thermal cracking result from thermal stress induced by rapid and large heat generation at high slip rate. Increase in wear rate of gouge with slip velocity is explained by the reduction of rock strength and enhancement of thermal cracking by temperature rise. The transition from a reduction to increase of permeability by high velocity friction is observed around 10-16 m2 of permeability for intact rocks at 10 MPa of effective pressure. All elastic properties (S and P wave velocities, Poisson’s ratio) for all rocks are not changed by friction at low slip rate below 130 mm/s. S and P wave velocities for Aji granite and Indian sandstone are decreased and Poisson’s ratio is increased by high velocity friction. We observed the decrease in S and P wave velocities and the increase in Poisson’s ratio at 390 mm/s of slip velocity in Berea sandstone, though the changes in these properties were not observed at 1300 mm/s. Our results suggest that the temporal increase in shear strength caused by the dissipation of pore pressure is expected due to the generation of thermal cracking along fault zone, and thus the dynamic permeability change can act as a break of slip. The sudden increase in permeability for impermeable rocks can explain the hydro-geochemical phenomena after earthquake reported by Claesson et al. (2004). Claesson, L. et al., 2004. Hydrogeochemical changes before and after a major earthquake, Geology, 32, 641-644.

Sakaguchi, M.; Tanikawa, W.; Hirose, T.; Tadai, O.; Lin, W.

2009-12-01

163

Reinforced Concrete Fiber Beam Element with Bond-Slip  

Microsoft Academic Search

This paper presents a new reinforced concrete beam finite element that explicitly accounts for the slip between the reinforcing bars and the surrounding concrete. The element formulation combines the fiber- section model with the finite-element model of a reinforcing bar with continuous slip. The section model retains the plane-section assumption, but the steel fiber strains are computed as the sum

Giorgio Monti; Enrico Spacone

2000-01-01

164

Technical properties of slips for hot casting under pressure  

Microsoft Academic Search

The use of the thermoplastic method for manufacturing small articles of borosilicate glass for the frames of semiconductor devices has necessitated an investigation of the properties of the casting slip. Casting slip consists of a suspension of finely milled glass powder and organic bond. This article gives the results of an investigation of the effect of dispersion of the powder,

V. G. Bezborodov

1968-01-01

165

Discussion of slip boundary on fibrous filter media  

Microsoft Academic Search

In modeling fibrous filter media, it is important to consider the phenomena of slip on the fiber surface because of the Knudsen number limit. In this paper the available analytical expressions for slip boundary were summarized and applied on a novel fibrous filter media model. Experimental data of the pressure drop on the filter media was used to validate the

Bin Zhou; Xiaosong Zhang; Paolo Tronville

2010-01-01

166

Sensitivity of static stress calculations to the earthquake slip distribution  

E-print Network

produce stress fields consistent with the aftershock distribution when very near-fault events are excludedSensitivity of static stress calculations to the earthquake slip distribution Sandy Steacy investigate this issue by constructing a time-ordered sequence of slip solutions for the Landers earthquake

167

Dynamics of dip-slip faulting: Explorations in two dimensions  

Microsoft Academic Search

Dynamic models of earthquake rupture and slip are a powerful method by which to investigate the physics of earthquakes. Owing to both conceptual and computational constraints, dynamic earthquake models have largely been limited to cases with geometrical symmetry, such as faults in unbounded media or vertical faults. However, there are both observational and theoretical reasons to believe that nonvertical dip-slip

David D. Oglesby; Ralph J. Archuleta; Stefan B. Nielsen

2000-01-01

168

Slip Flow through Colloidal Crystals of Varying Particle Diameter  

PubMed Central

Slip flow of water through silica colloidal crystals was investigated experimentally for 8 different particle diameters, which have hydraulic channel radii ranging from 15 nm to 800 nm. The particle surfaces were silylated to be low in energy, with a water contact angle of 83°, as determined for a silylated flat surface. Flow rates through centimeter lengths of colloidal crystal were measured using a commercial liquid chromatograph for accurate comparisons of water and toluene flow rates using pressure gradients as high as 1010 Pa/m. Toluene exhibited no-slip Hagen-Poiseuille flow for all hydraulic channel radii. For water, the slip flow enhancement as a function of hydraulic channel radius was described well by the expected slip flow correction for Hagen-Poiseuille flow, and the data revealed a constant slip length of 63±3 nm. A flow enhancement of 20±2 was observed for the smallest hydraulic channel radius of 15 nm. The amount of slip flow was found to be independent of shear rate over a range of fluid velocities from 0.7 to 5.8 mm/s. The results support the applicability of the slip flow correction for channel radii as small as 15 nm. The work demonstrates that packed beds of submicrometer particles enable slip flow to be employed for high volume flow rates. PMID:23237590

Rogers, Benjamin J.; Wirth, Mary J.

2012-01-01

169

Slip-compensated path following for planetary exploration rovers  

Microsoft Academic Search

A system that enables continuous slip compensation for a Mars rover has been designed, imple- mented, and eld-tested. This system is composed of several components that allow the rover to accurately and continuously follow a designated path, compensate for slippage, and reach intended goals in high-slip environments. These components include: visual odometry, vehicle kinematics, a Kalman lter pose estimator, and

Daniel M. Helmick; Stergios I. Roumeliotis; Yang Cheng; Daniel S. Clouse; Max Bajracharya; Larry H. Matthies

2006-01-01

170

Slip Influence in the Course of Powerformer Loss of Excitation  

Microsoft Academic Search

Powerformer is a net new high-voltage generator that can be set directly to system. The simulation method of Powerformer loss of excitation based on MATLAB\\/simulink is proposed. Using the simulation method to study slip during Powerformer loss of field, and analyze slip impact on the electric value of Powerformer stator and rotor. From the rotor heating, it is not possible

Lv Yanling; Ge Baojun; Tao Dajun; Wang Jitao; Yang Mo

2010-01-01

171

Large area multiturn superfluid phase slip gyroscope Niels Brucknera)  

E-print Network

Large area multiturn superfluid phase slip gyroscope Niels Brucknera) and Richard Packard 15 November 2002 We have built and tested a large area multiturn superfluid 4 He phase slip gyroscope-of-principle model, with an improvement in sensitivity of 20 over any other superfluid 4 He gyroscope. We find

Packard, Richard E.

172

Learning and prediction of slip from visual information  

Microsoft Academic Search

This paper presents an approach for slip prediction from a distance for wheeled ground robots using visual information as input. Large amounts of slippage which can occur on certain surfaces, such as sandy slopes, will negatively affect rover mobility. Therefore, obtaining information about slip before entering such terrain can be very useful for better planning and avoiding these areas. To

Anelia Angelova; Larry Matthies; Daniel M. Helmick; Pietro Perona

2007-01-01

173

One-year stress relaxation of timber joints assembled with pretensioned bolts  

Microsoft Academic Search

In our previous study, great increases of hysteretic damping and initial slip resistance of timber joints were attained by\\u000a applying axial pretension to the steel fasteners. To evaluate the effectiveness of this method, 1-year stress-relaxation measurement\\u000a was carried out. Nine prestressed joints were prepared and three of them were restressed after 3 and then 6 months after the\\u000a initial prestressing.

Ali Awaludin; Takuro Hirai; Toshiro Hayashikawa; Yoshihisa Sasaki; Akio Oikawa

2008-01-01

174

Study of the viscoelastic behavior of cold-shrinkable joints for MV cables  

Microsoft Academic Search

A new technology to joint medium voltage cables has been introduced in recent years: cold-shrinkable joints are gradually replacing premolded slip-on and heat-shrink type products. One of the key concerns on the functioning of such products is about the ability to shrink onto the cable insulation after long periods of storage time. The viscoelastic properties of the materials used in

J. Cardinaels; P. Heuillet; P. Meyer

1999-01-01

175

Synchronization of coupled stick-slip oscillators  

NASA Astrophysics Data System (ADS)

A rationale is provided for the emergence of synchronization in a system of coupled oscillators in a stick-slip motion. The single oscillator has a limit cycle in a region of the state space for each parameter set beyond the supercritical Hopf bifurcation. The two-oscillator system that has similar weakly coupled oscillators exhibits synchronization in a parameter range. The synchronization has an anti-phase nature for an identical pair. However, it tends to be more in-phase for a non-identical pair with a rather weak coupling. A system of three identical oscillators (1, 2, and 3) coupled in a line (with two springs k12=k23) exhibits synchronization with two of them (1 and 2 or 2 and 3) being nearly in-phase. These collective behaviours are systematically estimated using the phase reduction method.

Sugiura, N.; Hori, T.; Kawamura, Y.

2014-02-01

176

Proprioception and joint stability  

Microsoft Academic Search

In the present paper the current clinical knowledge about proprioception is given for the shoulder, knee, ankle, elbow and the radiocarpal joint. Proprioceptive capabilities are decreased after joint injuries such as ACL or meniscus tears, shoulder dislocation, ankle sprain and in joints with degenerative joint disease. Some surgical procedures seem to restore the proprioceptive abilities; others do not. Elastic knee

J. Jerosch; M. Prymka

1996-01-01

177

Slip stick and the rapid dynamics of static friction  

NASA Astrophysics Data System (ADS)

Understanding the dynamics of frictional sliding is important for various fields,ranging from engineering to geophysics. We focus on the local dynamics of slip events that arrest before traversing an entire frictional interface. Our experiments measure slip and contact area evolution, at timescales spanning µsec to hundreds of seconds. We recognize three distinct phases of local slip dynamics. The first phase consists of a rapid drop in the contact area, accompanied by the onset of local slip at velocities of ~10-25cm/sec that occurs immediately upon passage of a rapid detachment front. The second phase consists of steady-sliding at constant lower velocities (0.3-1cm/sec). The final phase comprises logarithmic aging of the contact area, which starts immediately upon slip arrest, within 400µsec of the front arrival.

Ben-David, O.; Fineberg, J.

2012-04-01

178

Numerical Investigations of Slip Phenomena in Centrifugal Compressor Impellers  

NASA Astrophysics Data System (ADS)

This study systematically investigates the slip phenomena in the centrifugal air compressor impellers by CFD. Eight impeller blades for different specific speeds, wrap angles and exit blade angles are designed by compressor design software to analyze their flow fields. Except for the above three variables, flow rate and number of blades are the other two. Results show that the deviation angle decreases as the flow rate increases. The specific speed is not an important parameter regarding deviation angle or slip factor for general centrifugal compressor impellers. The slip onset position is closely related to the position of the peak value in the blade loading factor distribution. When no recirculation flow is present at the shroud, the variations of slip factor under various flow rates are mainly determined by difference between maximum blade angle and exit blade angle, ??max-2. The solidity should be of little importance to slip factor correlations in centrifugal compressor impellers.

Huang, Jeng-Min; Luo, Kai-Wei; Chen, Ching-Fu; Chiang, Chung-Ping; Wu, Teng-Yuan; Chen, Chun-Han

2013-03-01

179

Coseismic slip inversion based on InSAR arc measurements  

NASA Astrophysics Data System (ADS)

We present a new method for inverting coseismic slip distribution based on arc measurements of InSAR interferograms. The method only solves the integer ambiguities on the selected arcs so that the challenging task from global unwrapping of low coherence interferograms can be avoided. The simulated experiment results show that the new method recovered the given slip distribution well at different coherence quality levels. However, the conventional method with global interferogram unwrapping fails when the interferogram has some isolated areas. In addition, the new method is capable of using surface rupture offset data gathered in the field. We apply the proposed method to study the 2010 Yushu, China Ms 7.1 earthquake. Inclusion of field data can help to enhance the results of fault slip inversion. It derives a maximum slip of ∼3 m, larger than the published coseismic slip results on this event, but agreeing with the largest offset of 3.2 m from field investigation.

Wang, C.; Ding, X.; Li, Q.

2014-03-01

180

Coseismic slip inversion based on InSAR arc measurements  

NASA Astrophysics Data System (ADS)

We present a new method for inverting coseismic slip distribution based on arc measurements of InSAR interferograms. The method only solves the integer ambiguities on the selected arcs so that the challenging task from global unwrapping of low coherence interferograms can be avoided. The simulated experiment results show that the new method recovered the given slip distribution well in different coherence quality level. However, the conventional method with global interferogram unwrapping fails when the interferogram has some isolated areas. In addition, the new method is capable of using surface rupture offset data gathered in the field. We apply the proposed method to study the 2010 Yushu, China Ms = 7.1 earthquake. Inclusion of field data can help to enhance the results of fault slip inversion. It derives a maximum slip of ∼3 m, larger than the published coseismic slip results on this event, but agreeing with the largest offset of 3.2 m from field investigation.

Wang, C.; Ding, X.; Li, Q.

2013-12-01

181

Thermal slip for liquids at rough solid surfaces  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulation is used to examine the thermal slip of liquids at rough solid surfaces as characterized by fractal Cantor structures. The temperature profiles, potential energy distributions, thermal slip, and interfacial thermal resistance are investigated and evaluated for a variety of surface topographies. In addition, the effects of liquid-solid interaction, surface stiffness, and boundary condition on thermal slip length are presented. Our results indicate that the presence of roughness expands the low potential energy regions in adjacent liquids, enhances the energy transfer at liquid-solid interface, and decreases the thermal slip. Interestingly, the thermal slip length and thermal resistance for liquids in contact with solid surfaces depends not only on the statistical roughness height, but also on the fractal dimension (i.e., topographical spectrum).

Zhang, Chengbin; Chen, Yongping; Peterson, G. P.

2014-06-01

182

Constraining fault constitutive behavior with slip and stress heterogeneity  

USGS Publications Warehouse

We study how enforcing self-consistency in the statistical properties of the preshear and postshear stress on a fault can be used to constrain fault constitutive behavior beyond that required to produce a desired spatial and temporal evolution of slip in a single event. We explore features of rupture dynamics that (1) lead to slip heterogeneity in earthquake ruptures and (2) maintain these conditions following rupture, so that the stress field is compatible with the generation of aftershocks and facilitates heterogeneous slip in subsequent events. Our three-dimensional fmite element simulations of magnitude 7 events on a vertical, planar strike-slip fault show that the conditions that lead to slip heterogeneity remain in place after large events when the dynamic stress drop (initial shear stress) and breakdown work (fracture energy) are spatially heterogeneous. In these models the breakdown work is on the order of MJ/m2, which is comparable to the radiated energy. These conditions producing slip heterogeneity also tend to produce narrower slip pulses independent of a slip rate dependence in the fault constitutive model. An alternative mechanism for generating these confined slip pulses appears to be fault constitutive models that have a stronger rate dependence, which also makes them difficult to implement in numerical models. We hypothesize that self-consistent ruptures could also be produced by very narrow slip pulses propagating in a self-sustaining heterogeneous stress field with breakdown work comparable to fracture energy estimates of kJ/M2. Copyright 2008 by the American Geophysical Union.

Aagaard, B. T.; Heaton, T. H.

2008-01-01

183

Preslip and cascade processes initiating laboratory stick slip  

NASA Astrophysics Data System (ADS)

modeling studies have explored whether earthquakes begin with a large aseismic nucleation process or initiate dynamically from the rapid growth of a smaller instability in a "cascade-up" process. To explore such a case in the laboratory, we study the initiation of dynamic rupture (stick slip) of a smooth saw-cut fault in a 76 mm diameter cylindrical granite laboratory sample at 40-120 MPa confining pressure. We use a high dynamic range recording system to directly compare the seismic waves radiated during the stick-slip event to those radiated from tiny (M -6) discrete seismic events, commonly known as acoustic emissions (AEs), that occur in the seconds prior to each large stick slip. The seismic moments, focal mechanisms, locations, and timing of the AEs all contribute to our understanding of their mechanics and provide us with information about the stick-slip nucleation process. In a sequence of 10 stick slips, the first few microseconds of the signals recorded from stick-slip instabilities are nearly indistinguishable from those of premonitory AEs. In this sense, it appears that each stick slip begins as an AE event that rapidly (~20 µs) grows about 2 orders of magnitude in linear dimension and ruptures the entire 150 mm length of the simulated fault. We also measure accelerating fault slip in the final seconds before stick slip. We estimate that this slip is at least 98% aseismic and that it both weakens the fault and produces AEs that will eventually cascade-up to initiate the larger dynamic rupture.

McLaskey, Gregory C.; Lockner, David A.

2014-08-01

184

Slow slip, tremor, and local earthquakes prior to the Mw 7.4 megathrust event in Oaxaca  

NASA Astrophysics Data System (ADS)

The search for observations to demonstrate slow slip phenomena can trigger large and damaging earthquakes is fueled by theoretical predictions that slip in the deeper transitional zone can promote failure in the shallow seismogenic zone. If such a link is verified, then operational earthquake forecasting could be improved by incorporating more slow slip behaviors. The subduction zone in Oaxaca, Mexico provides an ideal locality to investigate this potential relationship, where a joint seismic-geodetic network provides a multi-year record of traditional earthquakes, tectonic tremor, and slow slip events (SSE) prior to the recent March 12, 2012 Mw 7.4 megathrust Ometepec earthquake. Geodetically detected SSEs are observed for 2-3 months every 1-2 years, where stronger signals originate in the updip portion of the transition zone. In the months preceding the Ometepec mainshock, visual inspection of GPS time series for the 2011-2012 SSE suggests a migration of slip from east to west, along strike toward the source region of the earthquake. Preliminary models of the time series confirm slip ends just downdip of the epicenter in the weeks prior to the earthquake. While slow slip activity is prominent in the months leading up to the mainshock, tremor activity remains near background levels for much of that time, particularly in the days leading up to the earthquake. Observations from single station frequency scanning, beginning in mid-2006 show tremor activity is located further down-dip than SSE and occur over relatively short time periods, 2-10 days and recurs as often as every 2-3 months. Curiously, if we look at the preceding year, more tremor activity is detected during the nearly 6-month 2011 slow slip event. To further investigate the relationship between SSEs, tremor, and megathrust earthquakes, we use a multi-station template waveform matching technique to detect and locate events several of orders of magnitude smaller than would be possible using traditional techniques. Visible aftershocks are used as templates to identify and characterize multi-year pre-event seismicity of specific "template families" near or within the eventual rupture zone. Preliminary analysis suggests that families of earthquakes in between the SSE and the Mw 7.4 epicenter are active in the weeks prior to the mainshock. Examination of several years of seismicity prior to the megathrust event shows that some families are more active during SSEs. Despite an unclear correlation between tremor and the megathrust event, preliminary results indicate a slow slip event and template earthquake families are active prior to the Ometepec earthquake. While detailed geodetic modeling is underway to better define the source zones of slow slip over time, our hypothesis is that periods of slow slip at the shallower end of the transition zone increase the potential for a megathrust event, whereas periods of slow slip focused towards the deeper end of the transition zone increase tremor activity.

Sit, S. M.; Brudzinski, M. R.; Graham, S. E.; Colella, H. V.; Holtkamp, S. G.; Ghouse, N.; Cabral-Cano, E.; Arciniega-Ceballos, A.; DeMets, C.

2013-05-01

185

Design and Analysis of Closed Loop Microprocessor Based Static Slip Energy Recovery Controlled Slip Ring Induction Motor Drive  

Microsoft Academic Search

In this paper the complete design and analysis of microprocessor based closed loop static slip energy recovery controlled slip ring induction motor drive is presented. The speed and current controllers are implemented using INTEL-8085 microprocessor. The set of non -linear differential equations of the drive based on d c equivalent circuit are linearized around an operating point. Using forward approximation

B. K. SINGH

186

Slip-Length Scaling in Large Earthquakes: The Role of Deep-Penetrating Slip below the Seismogenic Layer  

E-print Network

Slip-Length Scaling in Large Earthquakes: The Role of Deep-Penetrating Slip below the Seismogenic with earthquake rupture length for lengths far beyond the length scale set by the seismogenic layer be confined to the seismogenic layer, implies that earthquake stress drop increases as a function of rupture

Shaw, Bruce E.

187

Experimental investigation of frictional melting of argillite at high slip rates: Implications for seismic slip in subduction-accretion complexes  

E-print Network

melting occurred along illite-rich, argillite-derived slip zones during subduction earthquakes. We and laboratory studies suggest that pseudo- tachylytes were formed by frictional melting of illite-rich slip zone at $1100°C [Ujiie et al., 2007]. Therefore insights into the dynamic shear strength of illite

Fialko, Yuri

188

Experimental Characterization of Hysteresis in a Revolute Joint for Precision Deployable Structures  

NASA Technical Reports Server (NTRS)

Recent studies of the micro-dynamic behavior of a deployable telescope metering truss have identified instabilities in the equilibrium shape of the truss in response to low-energy dynamic loading. Analyses indicate that these micro-dynamic instabilities arise from stick-slip friction within the truss joints (e.g., hinges and latches). The present study characterizes the low-magnitude quasi-static load cycle response of the precision revolute joints incorporated in the deployable telescope metering truss, and specifically, the hysteretic response of these joints caused by stick-slip friction within the joint. Detailed descriptions are presented of the test setup and data reduction algorithms, including discussions of data-error sources and data-filtering techniques. Test results are presented from thirteen specimens, and the effects of joint preload and manufacturing tolerances are investigated. Using a simplified model of stick-slip friction, a relationship is made between joint load-cycle behavior and micro-dynamic dimensional instabilities in the deployable telescope metering truss.

Lake, Mark S.; Fung, Jimmy; Gloss, Kevin; Liechty, Derek S.

1997-01-01

189

Shallow slip deficit due to large strike-slip earthquakes in dynamic rupture simulations with elasto-plastic off-fault response  

Microsoft Academic Search

Slip inversions of geodetic data from several large (magnitude ˜7) strike-slip earthquakes point to coseismic slip deficit at shallow depths (<3-4 km), that is, coseismic slip appears to decrease towards the Earth surface. While the inferred slip distribution may be consistent with laboratory-derived rate and state friction laws suggesting that the uppermost brittle crust may be velocity strengthening, there remains

Y. Kaneko; Y. Fialko

2011-01-01

190

A simple stick-slip and creep-slip model for repeating earthquakes and its implication for microearthquakes at Parkfield  

USGS Publications Warehouse

If repeating earthquakes are represented by circular ruptures, have constant stress drops, and experience no aseismic slip, then their recurrence times should vary with seismic moment as tr ?? Mo1/3. In contrast, the observed variation for small, characteristic repeating earthquakes along a creeping segment of the San Andreas fault at Parkfield (Nadeau and Johnson, 1998) is much weaker. Also, the Parkfield repeating earthquakes have much longer recurrence intervals than expected if the static stress drop is 10 MPa and if the loading velocity VL is assumed equal to the geodetically inferred slip rate of the fault Vf. To resolve these discrepancies, previous studies have assumed no aseismic slip during the interseismic period, implying either high stress drop or VL ??? Vf. In this study, we show that a model that includes aseismic slip provides a plausible alternative explanation for the Parkfield repeating earthquakes. Our model of a repeating earthquake is a fixed-area fault patch that is allowed to continuously creep and strain harden until reaching a failure threshold stress. The strain hardening is represented by a linear coefficient C, which when much greater than the elastic loading stiffness k leads to relatively small interseismic slip (stick-slip). When C and k are of similar size creep-slip occurs, in which relatively large aseismic slip accrues prior to failure. Because fault-patch stiffness varies with patch radius, if C is independent of radius, then the model predicts that the relative amount of seismic to total slip increases with increasing radius or Mo, consistent with variations in slip required to explain the Parkfield data. The model predicts a weak variation in tr with Mo similar to the Parkfield data.

Beeler, N. M.; Lockner, D. L.; Hickman, S. H.

2001-01-01

191

Real-time inversions for finite fault slip models and rupture geometry based on high-rate GPS data  

NASA Astrophysics Data System (ADS)

We present an inversion strategy capable of using real-time high-rate GPS data to simultaneously solve for a distributed slip model and fault geometry in real time as a rupture unfolds. We employ Bayesian inference to find the optimal fault geometry and the distribution of possible slip models for that geometry using a simple analytical solution. By adopting an analytical Bayesian approach, we can solve this complex inversion problem (including calculating the uncertainties on our results) in real time. Furthermore, since the joint inversion for distributed slip and fault geometry can be computed in real time, the time required to obtain a source model of the earthquake does not depend on the computational cost. Instead, the time required is controlled by the duration of the rupture and the time required for information to propagate from the source to the receivers. We apply our modeling approach, called Bayesian Evidence-based Fault Orientation and Real-time Earthquake Slip, to the 2011 Tohoku-oki earthquake, 2003 Tokachi-oki earthquake, and a simulated Hayward fault earthquake. In all three cases, the inversion recovers the magnitude, spatial distribution of slip, and fault geometry in real time. Since our inversion relies on static offsets estimated from real-time high-rate GPS data, we also present performance tests of various approaches to estimating quasi-static offsets in real time. We find that the raw high-rate time series are the best data to use for determining the moment magnitude of the event, but slightly smoothing the raw time series helps stabilize the inversion for fault geometry.

Minson, S. E.; Murray, Jessica R.; Langbein, John O.; Gomberg, Joan S.

2014-04-01

192

Butt Joint Tool Commissioning  

SciTech Connect

ITER Central Solenoid uses butt joints for connecting the pancakes in the CS module. The principles of the butt joining of the CICC were developed by the JAPT during CSMC project. The difference between the CSMC butt joint and the CS butt joint is that the CS butt joint is an in-line joint, while the CSMC is a double joint through a hairpin jumper. The CS butt joint has to carry the hoop load. The straight length of the joint is only 320 mm, and the vacuum chamber around the joint has to have a split in the clamp shell. These requirements are challenging. Fig.1 presents a CSMC joint, and Fig.2 shows a CS butt joint. The butt joint procedure was verified and demonstrated. The tool is capable of achieving all specified parameters. The vacuum in the end was a little higher than the target, which is not critical and readily correctable. We consider, tentatively that the procedure is established. Unexpectedly, we discover significant temperature nonuniformity in the joint cross section, which is not formally a violation of the specs, but is a point of concern. All testing parameters are recorded for QA purposes. We plan to modify the butt joining tool to improve its convenience of operation and provide all features necessary for production of butt joints by qualified personnel.

Martovetsky, N N

2007-12-06

193

Numerical Investigations of the Dynamic Shear Behavior of Rough Rock Joints  

NASA Astrophysics Data System (ADS)

The dynamic shear behavior of rock joints is significant to both rock engineering and earthquake dynamics. With the discrete element method (DEM), the dynamic direct-shear tests on the rough rock joints with 3D (sinusoidal or random) surface morphologies are simulated and discussed. Evolution of the friction coefficient with the slip displacement shows that the 3D DEM joint model can accurately reproduce the initial strengthening, slip-weakening, and steady-sliding responses of real rock joints. Energy analyses show that the strengthening and weakening behavior of the rock joint are mainly attributed to the rapid accumulation and release of the elastic energy in the joint. Then, effects of the surface roughness and the normal stress on the friction coefficient and the micro shear deformation mechanisms, mainly volume change and asperity damage, of the rock joint are investigated. The results show that the peak friction coefficient increases logarithmically with the increasing surface roughness, but decreases exponentially with the increasing normal stress. In addition, the rougher rock joint exhibits both higher joint dilation and asperity degradation. However, high normal stress constrains the joint dilation, but promotes the degree of asperity degradation significantly. Lastly, the effects of the 3D surface morphology on the shear behavior of the rock joint are investigated with a directional roughness parameter. It is observed that the anisotropy of the surface roughness consequently results in the variation of the peak friction coefficient of the joint corresponding to different shearing directions as well as the micro shear deformation mechanisms, e.g., the extent of joint dilation.

Huang, Junyu; Xu, Songlin; Hu, Shisheng

2014-09-01

194

Experimental investigation of slip instability associated with excess pore pressure  

NASA Astrophysics Data System (ADS)

Slow slip events, including non-volcanic tremors, low- and very low-frequency earthquakes, are observed at both the updip and downdip limits of several subduction regions. Recent studies indicate that similar to regular earthquake, these low frequency events rise from shear slip. It is generally accepted that elevated pore fluid pressure plays a significant role in triggering such slip events. In this study, we conducted deformation experiments on porous sedimentary rocks (both intact and saw-cut samples) to investigate the effect of pore fluid pressure on failure mechanisms and slip behaviors. In the first set of experiments, the pore fluid pressure is kept constant during deformation at fully drained conditions. The second set of experiments was conducted at conditions identical to the first until the onset of inelastic failure. At the onset of inelastic failure, we increased pore fluid pressure while continuing the loading at the same strain rate. Comparison of the failure modes and slip behaviors of these two sets of experiments shows interesting results. At low effective pressure, porous rocks failed by brittle faulting. In the brittle faulting regime, samples deformed with excess pore pressure have lower shear strengths compared to samples deformed at the same stress conditions at normal pore pressure. This is consistent with the reported seismicity increase due to wastewater injections. However, there is no detectable different slip behaviors between the two sets. As effective pressure increases, brittle faulting is inhibited and brittle-ductile transition occurs. In the transitional regime, samples deformed with excess pore pressure exhibit slip weakening whereas their normal pore pressure counterparts show strengthening behaviors, which demonstrates that high pore pressure enables slip instability in otherwise stable conditions. Our data show that the stress drop during the high pore pressure induced slip event at the transitional regime is much smaller than that in the brittle regime. Furthermore, between the high pore pressure induced slip event and the slip event during brittle faulting, there is a measurable difference in the relationship of fracture energy versus slip duration, resembling the difference in moment-duration scaling relations observed in slow slip events versus regular earthquakes. We performed quantitative microstructural analyses on the deformed samples to understand the failure mechanisms associated with the slip and excess pore pressure. This study provides the first experimental evidence that excess pore fluid pressure could induce slow slip in an otherwise aseismic fault whereas it enhances seismic slip along a seismic fault. The prevalence of the slow slip events suggests that the phenomenon is not restricted to specific rock types. While the deformation mechanisms responsible for the brittle-ductile transition and the pore pressure increase vary considerably from one tectonic setting to another, our experimental data support the idea that instabilities triggered by high pore pressure can produce slow events in the transitional regime.

Ougier-simonin, A.; Zhu, W.; Banker, J. S.

2012-12-01

195

Laboratory analysis updates fault slip formula  

NASA Astrophysics Data System (ADS)

The rate at which one rock slab slides past another, such as along a fault or fracture, depends on the strengths of the applied forces and the friction between the blocks. Though simple in concept, accurately modeling the interactions—especially the extreme cases of prolonged stress accumulation or the sudden rupture of an earthquake—is difficult. Researchers rely on the rate- and state-dependent friction law (RSF) to estimate the slip velocity in a fracture from the imposed stresses. The empirical RSF is itself broken down into two component parts: the constitutive law, which describes how the rock reacts to external forces and pressures, and the evolution law, which attempts to explain how the friction at the fracture interface changes under varying amounts of stress. Embedded within the constitutive law are two empirical parameterizations: the direct effect coefficient, which accounts for stresses perpendicular to the direction of motion, and the state variable, which is derived from the evolution law and describes changes in the physical state of the rock at the friction interface.

Schultz, Colin

2012-05-01

196

Seasonal variation of slipped capital femoral epiphysis.  

PubMed

During the 18-year period 1980-1997, 1103 patients were treated as in-patients for slipped capital femoral epiphysis (SCFE) in Scottish hospitals. This paper reports a significant seasonal variation, especially in male patients, with an excess admitted in the autumn. Examining the physiological seasonality of the monthly increment of growth in height and weight in childhood, we hypothesised that these physiological rhythms, while not pathogenetic, may be responsible for the timing of the seasonal features of SCFE. Previously published studies suggest that the average time between first symptoms and diagnosis is 3 to 5 months. The condition may start with the spring peak in growth and become more symptomatic with the autumn peak in weight. In conclusion, we report a new epidemiological finding, but, in accordance with other studies, we cannot provide a certain aetiological explanation. The timing, but not the pathogenesis, of admission to hospital for a SCFE might be related to the timing in the year of seasonal increments of height in spring and weight in autumn. It is tempting to draw attention to associations with environmental features. For example, in autumn there is the most rapid annual fall in temperature, and the hours of darkness are increasing from the autumn equinox to the winter solstice. However, there is no reason to conclude that these associations have anything to do with aetiology. PMID:11866078

Maffulli, Nicola; Douglas, A Stuart

2002-01-01

197

From frictional fingers to stick slip bubbles  

NASA Astrophysics Data System (ADS)

Gas intrusion into wet porous/deformable/granular media occurs in a wide range of natural and engineered settings. Examples include hydrocarbon recovery, carbon dioxide geo-sequestration, gas venting in sediments and volcanic eruptions. In the case where the intruding gas is able to displace particles and grains, local changes in granular packing fraction govern the evolution of flow paths, resulting in complex pattern formation of the displacement flow. Here we investigate flow patterning as a compressed gas displaces a granular mixture confined in the narrow gap of a Hele-Shaw cell. We find a surprising variety of different pattern formation dynamics, and present a unified phase diagram of the flow morphologies we observe. This talk will focus on one particular transition the system undergoes: from frictional fingers to stick slip bubbles. We show that the frictional fluid flow patterns depend on granular mass loading and system elasticity, analogous to the behaviour of the well-known spring-block sliding friction problem.

Sandnes, Bjørnar; Jørgen Måløy, Knut; Flekkøy, Eirik; Eriksen, Jon

2014-05-01

198

Analysis of fluid injection-induced fault reactivation and seismic slip in geothermal reservoirs  

NASA Astrophysics Data System (ADS)

explore the issue of fault reactivation induced in enhanced geothermal systems by fluid injection. Specifically, we investigate the role of late stage activation by thermal drawdown. A Thermal-Hydrological-Mechanical simulator incorporating a ubiquitous joint constitutive model is used to systematically simulate the seismic slip of an embedded critically stressed strike-slip fault. We examine the effects of both pore pressure perturbation and thermal shrinkage stress on the magnitude of the resulting events and timing. We analyze the sensitivity of event magnitude and timing to changes in the permeability of the fault and fractured host, fracture spacing, injection temperature, and fault stress obliquity. From this we determine that (1) the fault permeability does not affect the timing of the events nor their size, since fluid transmission and cooling rate are controlled by the permeability of the host formation. (2) When the fractured medium permeability is reduced (from 10-13 to 10-16 m2), the timing of the event is proportionately delayed (by a corresponding 3 orders of magnitude). (3) Injection temperature only influences the magnitude but not the timing of the secondary thermal event. The larger the temperature differences between that of the injected fluid and the ambient rock, the larger the magnitude of the secondary slip event. (4) For equivalent permeabilities, changing the fracture spacing (10 m-50 m-100 m) primarily influences the rate of heat energy transfer and thermal drawdown within the reservoir. Smaller spacing between fractures results in more rapid thermal recovery but does not significantly influence the timing of the secondary thermal rupture.

Gan, Quan; Elsworth, Derek

2014-04-01

199

Bone remodeling of a femoral head after transtrochanteric rotational osteotomy for osteonecrosis associated with slipped capital femoral epiphysis: a case report  

Microsoft Academic Search

A rare case of a 12-year-old boy on whom a joint-preserving operation for osteonecrosis after slipped capital femoral epiphysis\\u000a (SCFE) was performed, is described. Firstly, in situ pinning was performed for acute-on-chronic SCFE. However, osteonecrosis\\u000a and collapse of the femoral head occurred at 7 months after surgery. Secondly, transtrochanteric rotational osteotomy (TRO)\\u000a was performed against progression of the collapse of the

Takuma Yamasaki; Yuji Yasunaga; Takashi Hisatome; Ryuji Tanaka; Mitsuo Ochi

2005-01-01

200

Large displacement spherical joint  

DOEpatents

A new class of spherical joints has a very large accessible full cone angle, a property which is beneficial for a wide range of applications. Despite the large cone angles, these joints move freely without singularities.

Bieg, Lothar F. (Albuquerque, NM); Benavides, Gilbert L. (Albuquerque, NM)

2002-01-01

201

Joint Injection/Aspiration  

MedlinePLUS

... osteoarthritis. What usually is injected into the joint space? Corticosteroids (such as methylprednisolone and triamcinolone formulated to ... for producing inflammation and pain within the joint space. Although corticosteroids may also be successfully used in ...

202

Brittle-viscous deformation, slow slip, and tremor  

NASA Astrophysics Data System (ADS)

Geophysical observations have illuminated a spectrum of fault slip styles from continuous aseismic sliding to fast earthquake slip. We study exhumed intercalated lenses of oceanic crust and sedimentary rocks, deformed to high shear strains. Deformation was partitioned between fractured, rigid blocks, with lengths of tens to hundreds of meters, and surrounding metapelites characterized by interconnected phyllosilicate networks. Under inferred conditions of low effective stress at temperatures > 500°C, locally and transiently elevated shear strain rate in phyllosilicates deforming by dislocation creep can reach those needed for transient slow slip. Concurrently, increased matrix strain rate likely stimulates brittle failure in rigid lenses. The ubiquitous presence of quartz veins and microfractures within rigid material provides evidence for brittle deformation occurring coincident with viscous shearing flow. We suggest that geophysically observed tremor and slow slip may be a manifestation of strain partitioning, where deformation is accommodated viscously in a matrix enveloping rigid lenses.

Fagereng, Åke; Hillary, Graeme W. B.; Diener, Johann F. A.

2014-06-01

203

Toward understanding slip inversion uncertainty and artifacts Ji Zahradnk1  

E-print Network

. They are analyzed using two independent slip inversion methods with similar results, bias of the rupture speed A and C. They claim "confirmation" of asperity A and broadly discuss whether B or C is more relevan

Cerveny, Vlastislav

204

Non-slipping domains of a pulled spool  

NASA Astrophysics Data System (ADS)

We have investigated the pulled spool by considering pulling angles up to 360{}^\\circ . Our focus was on downward pulling forces with pulling angles in the range of 180{}^\\circ to 360{}^\\circ . In this range we have found a domain of pulling angles where the spool never starts to slip independent of the strength of the pulling force. The size of the domain depends on the static friction coefficient and on the moment of inertia of the spool. The non-slipping domain is mainly formed around the critical angle where the static friction force becomes zero. For low static friction the non-slipping domain decays into two different domains. We have determined the limiting angles of the non-slipping domains and explored the transitions from a single domain to two separated domains in parameter space.

Wagner, Clemens; Vaterlaus, Andreas

2014-11-01

205

Memory Slips in Senior Years May Signal Dementia Risk  

MedlinePLUS

... sharing features on this page, please enable JavaScript. Memory Slips in Senior Years May Signal Dementia Risk ... September 24, 2014 Related MedlinePlus Pages Alzheimer's Disease Memory Seniors' Health WEDNESDAY, Sept. 24, 2014 (HealthDay News) -- ...

206

Frictional melting and stick-slip behavior in volcanic conduits  

NASA Astrophysics Data System (ADS)

Dome-building eruptions have catastrophic potential, with dome collapse leading to devastating pyroclastic flows with almost no precursory warning. During dome growth, the driving forces of the buoyant magma may be superseded by controls along conduit margins; where brittle fracture and sliding can lead to formation of lubricating cataclasite and gouge. Under extreme friction, pseudotachylyte may form at the conduit margin. Understanding the conduit margin processes is vital to understanding the continuation of an eruption and we postulate that pseudotachylyte generation could be the underlying cause of stick-slip motion and associated seismic "drumbeats", which are so commonly observed at dome-building volcanoes. This view is supported by field evidence in the form of pseudotachylytes identified in lava dome products at Soufrière Hills (Montserrat) and Mount St. Helens (USA). Both eruptions were characterised by repetitive, periodic seismicity and lava spine extrusion of highly viscous magma. High velocity rotary shear (HVR) experiments demonstrate the propensity for melting of the andesitic and dacitic material (from Soufrière Hills and Mount St. Helens respectively) at upper conduit stress conditions (<10 MPa). Starting from room temperature, frictional melting of the magmas occurs in under 1 s (<< 1 m) at 1.5 m/s (a speed that is achievable during stick-slip motion). At lower velocities melting occurs comparatively later due to dissipation of heat from the slip zone (e.g. 8-15 m at 0.1 m/s). Hence, given the ease with which melting is achieved in volcanic rocks, and considering the high ambient temperatures in volcanic conduits, frictional melting may thus be an inevitable consequence of viscous magma ascent. The shear resistance of the slip zone during the experiment is also monitored. Frictional melting induces a higher resistance to sliding than rock on rock, and viscous processes control the slip zone properties. Variable-rate HVR experiments which mimic rapid velocity fluctuations in stick-slip behavior demonstrate velocity-weakening behavior of melt, with a tendency for unstable slip. During ascent, magma may slip and undergo melting along the conduit margin. In the process the shear resistance of the slip zone is increased, acting as a viscous brake halting slip (the "stick" of stick-slip motion). Sufficient buoyancy-driven pressures from ascending magma below eventually overcome resistance to produce a rapid slip event (the "slip") along the melt-bearing slip zone, which is temporarily lubricated due to velocity-weakening. New magma below experiences the same slip event more slowly (as the magma decompresses) to produce a viscous brake and the process is repeated. This allows a fixed spatial locus that explains the repetitive drumbeat seismicity and the occurrence of "families" of similar seismic events. We conclude that stick-slip motion in volcanic conduits is a self-driving, frictional-melt-regulated force common to many dome building volcanoes.

Kendrick, Jackie Evan; Lavallee, Yan; Hirose, Takehiro; di Toro, Giulio; Hornby, Adrian Jakob; Hess, Kai-Uwe; Dingwell, Donald Bruce

2013-04-01

207

Slip, Trip and Fall Prevention for Healthcare Workers  

MedlinePLUS

... that emit light from all sides. 6.Inadequate Lighting Slip, Trip, and Fall Prevention | 21 Figure 7. ... over? Do mats slide around on the floor? Lighting (Check both inside and outside the healthcare facility.) ...

208

Constant Stress Drop Fits Earthquake Surface Slip-Length Data  

NASA Astrophysics Data System (ADS)

Slip at the surface of the Earth provides a direct window into the earthquake source. A longstanding controversy surrounds the scaling of average surface slip with rupture length, which shows the puzzling feature of continuing to increase with rupture length for lengths many times the seismogenic width. Here we show that a more careful treatment of how ruptures transition from small circular ruptures to large rectangular ruptures combined with an assumption of constant stress drop provides a new scaling law for slip versus length which (1) does an excellent job fitting the data, (2) gives an explanation for the large crossover lengthscale at which slip begins to saturate, and (3) supports constant stress drop scaling which matches that seen for small earthquakes. We additionally discuss how the new scaling can be usefully applied to seismic hazard estimates.

Shaw, B. E.

2011-12-01

209

Arch & Chord Joint Detail; Crossbracing Center Joint Detail; Chord, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Arch & Chord Joint Detail; Crossbracing Center Joint Detail; Chord, Panel Post, Tie & Diagonal Brace Joint Detail; Chord, Panel Post, Tie & Crossbracing Joint Detail - Dunlapsville Covered Bridge, Spanning East Fork Whitewater River, Dunlapsville, Union County, IN

210

Jointly Poisson processes  

Microsoft Academic Search

What constitutes jointly Poisson processes remains an unresolved issue. This report reviews the current state of the theory and indicates how the accepted but unproven model equals that resulting from the small time-interval limit of jointly Bernoulli processes. One intriguing consequence of these models is that jointly Poisson processes can only be positively correlated as measured by the correlation coefficient

D. H. Johnson; I. N. Goodman

2009-01-01

211

Distribution of strike-slip faults on Europa  

Microsoft Academic Search

Study of four different regions on Europa imaged by the Galileo spacecraft during its first 15 orbits has revealed 117 strike-slip faults. Europa appears to form preferentially right-lateral faults in the southern hemisphere and left-lateral faults in the northern hemisphere. This observation is consistent with a model where diurnal tides due to orbital eccentricity drive strike-slip motion through a process

Gregory Hoppa; Richard Greenberg; B. Randall Tufts; Paul Geissler; Cynthia Phillips; Moses Milazzo

2000-01-01

212

Strike-slip motion and double ridge formation on Europa  

Microsoft Academic Search

There is abundant observational evidence for strike-slip displacement on the surface of Europa. Strike-slip motion between crustal blocks produces shear heating and an increase in temperature. We model the shear heating within the ice crust using a two-dimensional, finite difference formulation, with a near-surface brittle layer of constant specified thickness and a Newtonian ductile layer beneath. We obtain a maximum

Francis Nimmo; Eric Gaidos

2002-01-01

213

Role of surface shape on boundary slip and velocity defect.  

PubMed

Although many gas-phase microfluidic devices contain curved surfaces, relatively little research has been conducted on the degree of slip over nonplanar surfaces. The present study demonstrates the influence of the surface shape (i.e., convex/concave) on the velocity slip and formation of the Knudsen layer. In addition, the study reveals that there is a simple relationship between the shear stress exerted on the surface and the velocity defect in the Knudsen layer. PMID:23005532

Dinler, Ali; Barber, Robert W; Emerson, David R; Stefanov, Stefan K; Orucoglu, Kamil

2012-07-01

214

Wheel rolling constraints and slip in mobile robots  

SciTech Connect

It is widely accepted that dead reckoning based on the rolling with no slip condition on wheels is not a reliable method to ascertain the position and orientation of a mobile robot for any reasonable distance. We establish that wheel slip is inevitable under the dynamic model of motion using classical results on the accessibility and controllability in nonlinear control theory and an analytical model of rolling of two linearly elastic bodies.

Shekhar, S.

1997-03-01

215

Wheel rolling constraints and slip in mobile robots  

SciTech Connect

It is widely accepted that dead reckoning based on the rolling with no slip condition on wheels is not a reliable method to ascertain the position and orientation of a mobile robot for any reasonable distance. The author establishes that wheel slip is inevitable under the dynamic model of motion using classical results on the accessibility and controllability in nonlinear control theory and an analytical model of rolling of two linearly elastic bodies.

Shekhar, S.

1997-03-01

216

Complementary slip distributions of 200 years of megathrust earthquakes  

NASA Astrophysics Data System (ADS)

Coral paleo-geodesy on the Mentawai Islands off western Sumatra has produced a multi-seismic-cycle geodetic record which provides physical constraints on the slip distributions of large and great earthquakes. Using a Monte Carlo forward modelling method we have estimated the slip on the great 1797 and 1833 earthquakes and show that their most likely slip distributions are not only complementary but leave unruptured areas on the megathrust which appear to have been filled by the M8.4 and 7.9 Bengkulu earthquakes and the M7.8 Pagai earthquake. These results are consistent with a model in which slip in future earthquakes is controlled not only by secular loading and stress interaction between recent earthquakes, but also by the stress footprints of previous earthquakes potentially over many earthquake cycles. We discuss these results in the context of recent great earthquakes and suggest a mathematical formalism which unites observations of the evolution of slip deficit through heterogeneous tectonic loading, seismic and aseismic slip over many earthquakes. We apply the method to the Mentawai region including 330 years of heterogeneous loading of the Sunda megathrust and slip due to more than 30 historical and instrumentally recorded earthquakes. This complex slip deficit field is heterogeneous not only in the strain energy but also in the resolution and we introduce a new technique to clearly visualise both. We show that these results are consistent with the well published threat of a large tsunamigenic earthquake off western Sumatra and make some comments on constraining the threat.

McCloskey, J.; NicBhloscaidh, M.; Naylor, M.

2012-12-01

217

Distribution of seismicity across strike-slip faults in California  

Microsoft Academic Search

The distribution of seismicity about strike-slip faults provides measurements of fault roughness and damage zone width. In California, seismicity decays with distance from strike-slip faults according to a power law ˜(1 + x2\\/d2)-gamma\\/2. This scaling relation holds out to a fault-normal distance x of 3-6 km and is compatible with a ``rough fault loading'' model in which the inner scale

Peter M. Powers; Thomas H. Jordan

2010-01-01

218

Distribution of seismicity across strike-slip faults in California  

Microsoft Academic Search

The distribution of seismicity about strike-slip faults provides measurements of fault roughness and damage zone width. In California, seismicity decays with distance from strike-slip faults according to a power law ?(1 + x2\\/d2)??\\/2. This scaling relation holds out to a fault-normal distance x of 3–6 km and is compatible with a “rough fault loading” model in which the inner scale

Peter M. Powers; Thomas H. Jordan

2010-01-01

219

Experimental study of stick-slip in Tennessee sandstone  

E-print Network

EXPERIMENTAL STUDY OF STICK-SLIP IN TENNESSEE SANDSTONE A Thesis by JOHN ARTHUR HUMSTON Submitted to the Graduate College of Texas AFM University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE August 1972... Major Subject: Geology EXPERIMENTAL STUDY OF STICK-SLIP IN TENNESSEE SANDSTONE A Thesis by JOHN ARTHUR HUMSTON Approved as to style and content by: Chair an Committee Member Head of Department August 1972 ABSTRACT Experimental Study of Stick...

Humston, John Arthur

2012-06-07

220

Foreshocks during the nucleation of stick-slip instability  

USGS Publications Warehouse

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 Sierra White granite. With 14 piezoelectric sensors, we simultaneously monitor seismic signals produced during the nucleation phase and subsequent dynamic rupture. We observe localized aseismic fault slip in an approximately meter-sized zone in the center of the fault, while the ends of the fault remain locked. Clusters of high-frequency foreshocks (Mw?~??6.5 to ?5.0) can occur in this slowly slipping zone 5–50?ms prior to the initiation of dynamic rupture; their occurrence appears to be dependent on the rate at which local shear stress is applied to the fault. The meter-sized nucleation zone is generally consistent with theoretical estimates, but source radii of the foreshocks (2 to 70?mm) are 1 to 2 orders of magnitude smaller than the theoretical minimum length scale over which earthquake nucleation can occur. We propose that frictional stability and the transition between seismic and aseismic slip are modulated by local stressing rate and that fault sections, which would typically slip aseismically, may radiate seismic waves if they are rapidly stressed. Fault behavior of this type may provide physical insight into the mechanics of foreshocks, tremor, repeating earthquake sequences, and a minimum earthquake source dimension.

McLaskey, Gregory C.; Kilgore, Brian D.

2013-01-01

221

Origins of oblique-slip faulting during caldera subsidence  

NASA Astrophysics Data System (ADS)

Although conventionally described as purely dip-slip, faults at caldera volcanoes may have a strike-slip displacement component. Examples occur in the calderas of Olympus Mons (Mars), Miyakejima (Japan), and Dolomieu (La Reunion). To investigate this phenomenon, we use numerical and analog simulations of caldera subsidence caused by magma reservoir deflation. The numerical models constrain mechanical causes of oblique-slip faulting from the three-dimensional stress field in the initial elastic phase of subsidence. The analog experiments directly characterize the development of oblique-slip faulting, especially in the later, non-elastic phases of subsidence. The combined results of both approaches can account for the orientation, mode, and location of oblique-slip faulting at natural calderas. Kinematically, oblique-slip faulting originates to resolve the following: (1) horizontal components of displacement that are directed radially toward the caldera center and (2) horizontal translation arising from off-centered or "asymmetric" subsidence. We informally call these two origins the "camera iris" and "sliding trapdoor" effects, respectively. Our findings emphasize the fundamentally three-dimensional nature of deformation during caldera subsidence. They hence provide an improved basis for analyzing structural, geodetic, and geophysical data from calderas, as well as analogous systems, such as mines and producing hydrocarbon reservoirs.

Holohan, Eoghan P.; Walter, Thomas R.; SchöPfer, Martin P. J.; Walsh, John J.; Wyk de Vries, Benjamin; Troll, Valentin R.

2013-04-01

222

Holocene slip rate along the Gyaring Co Fault, central Tibet  

NASA Astrophysics Data System (ADS)

geodetic measurements of interseismic deformation in interior Tibet suggest slow strain accumulation, active slip along the right-lateral Gyaring Co Fault is suggested to be between 8 and 21 mm/yr. Reliable geologic constraints on the slip rate along this fault are sparse. Here we document 12 ± 2 m of right-lateral displacement of lacustrine shorelines across the Gyaring Co Fault. Optically stimulated luminescence ages of the shorelines are tightly clustered between 4.1 and 4.4 ka. These data require an average slip rate of 2.2-3.2 mm/yr along the central Gyaring Co Fault during the latter half of the Holocene. Consideration of seismic cycle effects allows the possibility of slightly higher average slip rates, up to 2.2-4.5 mm/yr. Overall, our results suggest that the slip rate along the Gyaring Co Fault is similar to other strike-slip faults in interior Tibet, supporting the notion that active deformation in this region is distributed among numerous, slowly moving faults.

Shi, Xuhua; Kirby, Eric; Lu, Haijian; Robinson, Ruth; Furlong, Kevin P.; Wang, Erchie

2014-08-01

223

Cam deformity and hip degeneration are common after fixation of a slipped capital femoral epiphysis.  

PubMed

Background and purpose - Slipped capital femoral epiphysis is thought to result in cam deformity and femoroacetabular impingement. We examined: (1) cam-type deformity, (2) labral degeneration, chondrolabral damage, and osteoarthritic development, and (3) the clinical and patient-reported outcome after fixation of slipped capital femoral epiphysis (SCFE). Methods - We identified 28 patients who were treated with fixation of SCFE from 1991 to 1998. 17 patients with 24 affected hips were willing to participate and were evaluated 10-17 years postoperatively. Median age at surgery was 12 (10-14) years. Clinical examination, WOMAC, SF-36 measuring physical and mental function, a structured interview, radiography, and MRI examination were conducted at follow-up. Results - Median preoperative Southwick angle was 22o (IQR: 12-27). Follow-up radiographs showed cam deformity in 14 of the 24 affected hips and a Tönnis grade > 1 in 1 affected hip. MRI showed pathological alpha angles in 15 affected hips, labral degeneration in 13, and chondrolabral damage in 4. Median SF-36 physical score was 54 (IQR: 49-56) and median mental score was 56 (IQR: 54-58). These scores were comparable to those of a Danish population-based cohort of similar age and sex distribution. Median WOMAC score was 100 (IQR: 84-100). Interpretation - In 17 patients (24 affected hips), we found signs of cam deformity in 18 hips and early stages of joint degeneration in 10 hips. Our observations support the emerging consensus that SCFE is a precursor of cam deformity, FAI, and joint degeneration. Neither clinical examination nor SF-36 or WOMAC scores indicated physical compromise. PMID:25175666

Klit, Jakob; Gosvig, Kasper; Magnussen, Erland; Gelineck, John; Kallemose, Thomas; Søballe, Kjeld; Troelsen, Anders

2014-12-01

224

Dissipation of fast strike-slip faulting within and beyond northeastern Tibet  

Microsoft Academic Search

Recently published GPS measurements and Quaternary slip rates provide an opportunity to address how strike-slip faulting is accommodated and transferred at the northeastern margin of the Tibetan Plateau. Structural patterns, GPS velocities, and Quaternary fault slip rates indicate a transfer of left-lateral slip from the Kunlun fault northeast to the Haiyuan fault and minor crustal shortening and rotation within a

A. R. Duvall; M. K. Clark

2009-01-01

225

Probabilistic estimates of surface slip including the effects of creep and afterslip  

Microsoft Academic Search

We develop a methodology for probabilistic estimates of coseismic and postseismic surface slip for scenario earthquakes that explicitly includes the effects of creep and afterslip. We apply Monte Carlo simulations to include uncertainty from the Hanks and Bakun (2008) magnitude-area relation, distribution of slip, and the effect of creep on coseismic slip. We extract coseismic surface slip from a suite

B. Aagaard; J. J. Lienkaemper; D. P. Schwartz

2009-01-01

226

Measuring the evolution of slip surface roughness with LiDAR  

Microsoft Academic Search

Roughness of faults plays an important role in controlling the resistance of faults to slip, yet all faults do not have the same roughness. A previous study used ground-based LIDAR to analyze 12 fault surfaces from 8 localities in the Western United States, and inferred that small slip faults (slip <1 m) are rougher in the slip parallel direction than

J. J. Gilchrist; E. E. Brodsky; M. Steffeck; A. Sagy

2008-01-01

227

Brownian motion near a partial-slip boundary: A local probe of the no-slip condition  

E-print Network

Motivated by experimental evidence of violations of the no-slip boundary condition for liquid flow in micron-scale geometries, we propose a simple, complementary experimental technique that has certain advantages over previous studies. Instead of relying on externally-induced flow or probe motion, we suggest that colloidal diffusivity near solid surfaces contains signatures of the degree of fluid slip exhibited on those surfaces. To investigate, we calculate the image system for point forces (Stokeslets) oriented perpendicular and parallel to a surface with a finite slip length, analogous to Blake's solution for a Stokeslet near a no-slip wall. Notably, the image system for the point source and perpendicular Stokeslet contain the same singularities as Blake's solution; however, each is distributed along a line with a magnitude that decays exponentially over the slip length. The image system for the parallel Stokeslet involves a larger set of fundamental singularities, whose magnitude does not decay exponentially from the surface. Using these image systems, we determine the wall-induced correction to the diffusivity of a small spherical particle located `far' from the wall. We also calculate the coupled diffusivities between multiple particles near a partially-slipping wall. Because, in general, the diffusivity depends on `local' wall conditions, patterned surfaces would allow differential measurements to be obtained within a single experimental cell, eliminating potential cell-to-cell variability encountered in previous experiments. In addition to motivating the proposed experiments, our solutions for point forces and sources near a partial-slip wall will be useful for boundary integral calculations in slip systems.

Eric Lauga; Todd M. Squires

2005-06-09

228

Three-Dimensional Elastodynamic Simulations of Seismic and Aseismic Slip History of a Planar Strike-Slip Fault  

Microsoft Academic Search

Simulations of spontaneous slip accumulation in three-dimensional (3D) models enjoy a lot of interest because of their ability to clarify earthquake physics. We have been developing a 3D methodology for simulating the entire seismic and aseismic slip history of a fault subjected to slow tectonic loading. The algorithm, extended from the 2D study by Lapusta et al. (2000), allows us

N. Lapusta; Y. Liu

2006-01-01

229

Electromagnetic emissions during seismic nucleation phase of stick-slips  

NASA Astrophysics Data System (ADS)

I. Introduction The size of seismic nucleation is determined by the characteristic wavelength of slip surface topography, and some scaling laws are derived from it (Ohnaka and Shen, 1999). Alternative characteristic wavelength should be introduced for natural faults because they are associated with layers of fault gouge. Riedel shear will be an equivalent since it is a characteristic structure inside fault zones. II. Method of stick- slip experiments Experimental apparatus: tri-axial apparatus. Samples: granite and gabbro cylinders of 20mmx40mm. Precut surface: 50 degree against sample axis and mirror-finished. Simulated fault gouge: quartz and gabbro powder of 0.25g. Sensors: strain gauges for measurements of axial stress and slip distance as well as three shear strain gauges pasted along a slip surface, three pairs of electrodes for measurement of triboelectric potentials. Data acquisition: continuously and synchronously at 2MHz. Experimental procedure: loading of axial stress after holding at confining pressure of 80-180 MPa and shear stress at 250 MPa during 0.1-1 hour for compaction of gouge. III. Experimental results 1) Stick-slips on bare surfaces Fluctuations of the electrode potentials during main stick-slip events are 55-180mV. Gabbro and granite samples do not show significant differences in magnitude of electrode potential. Any experimental runs were not associated with nucleation phases. Prior to main stick-slip events spike-like signals of electrode potentials were sometimes found synchronously with very small stress drops less than 1MPa. The amplitudes are less than 30mV, and they decayed exponentially. 2) Stick-slips with fault gouge Stress drops and fluctuations of electrode potentials at main stick-slip events are 7-400 MPa, 17-200mV+. Significant differences in fluctuations of electrode potentials were not found between granite and gabbro samples. About 30% of all experimental runs were associated with a nucleation phase. Slip distance, stress drop, duration and the maximum fluctuation of electrode potentials were 0.02mm, 14MPa, 0.3sec and 20mV in an experimental run, and the latter three were 3.5MPa, 0.35sec and 4mV in another run. Three pairs of strain gauges recorded the initial site and its propagation of a seismic nucleation. The potentials of three pairs of electrodes also fluctuated synchronously. The pulse-like electrode signals were sometimes found also for these experiments. IV. Discussions and conclusions 1) The reason why the stick-slips on bare surfaces were not associated with a nucleation phase is attributed to mirror-finished smooth and flat precut surfaces. 2) Irrespective of granite or gabbro powders of fault gouge, there were not significant differences in magnitude of pulse-like fluctuations of electrode potentials. This is the case for main stick-slip events. These indicate that the causes of the electric signals are not piezoelectric effect but triboelectricity and/or fracto-emission. 3) Since the fluctuations of electrode potentials are synchronous with the initiation and propagation of a nucleation, the former is attributed to the latter. 4) It is very likely that nucleation is quasi-static slip on a Riedel shear because the length of a nuclei estimated from slip during nucleation phases is the same order as the length of Riedel shears.

Onuma, K.; Otsuki, K.

2008-12-01

230

Regional Slip Tendency Analysis of the Great Basin Region  

SciTech Connect

Slip and dilation tendency on the Great Basin fault surfaces (from the USGS Quaternary Fault Database) were calculated using 3DStress (software produced by Southwest Research Institute). Slip and dilation tendency are both unitless ratios of the resolved stresses applied to the fault plane by the measured ambient stress field. - Values range from a maximum of 1 (a fault plane ideally oriented to slip or dilate under ambient stress conditions) to zero (a fault plane with no potential to slip or dilate). - Slip and dilation tendency values were calculated for each fault in the Great Basin. As dip is unknown for many faults in the USGS Quaternary Fault Database, we made these calculations using the dip for each fault that would yield the maximum slip or dilation tendency. As such, these results should be viewed as maximum slip and dilation tendency. - The resulting along?fault and fault?to?fault variation in slip or dilation potential is a proxy for along fault and fault?to?fault variation in fluid flow conduit potential. Stress Magnitudes and directions were calculated across the entire Great Basin. Stress field variation within each focus area was approximated based on regional published data and the world stress database (Hickman et al., 2000; Hickman et al., 1998 Robertson?Tait et al., 2004; Hickman and Davatzes, 2010; Davatzes and Hickman, 2006; Blake and Davatzes 2011; Blake and Davatzes, 2012; Moeck et al., 2010; Moos and Ronne, 2010 and Reinecker et al., 2005). The minimum horizontal stress direction (Shmin) was contoured, and spatial bins with common Shmin directions were calculated. Based on this technique, we subdivided the Great Basin into nine regions (Shmin <070, 070140). Slip and dilation tendency were calculated using 3DStress for the faults within each region using the mean Shmin for the region. Shmin variation throughout Great Basin are shown on Figure 3. For faults within the Great Basin proper, we applied a normal faulting stress regime, where the vertical stress (sv) is larger than the maximum horizontal stress (shmax), which is larger than the minimum horizontal stress (sv>shmax>shmin). Based on visual inspection of the limited stress magnitude data in the Great Basin, we used magnitudes such that shmin/shmax = .527 and shmin/sv= .46. These values are consistent with stress magnitude data at both Dixie Valley (Hickman et al., 2000) and Yucca Mountain (Stock et al., 1985). For faults within the Walker Lane/Eastern California Shear Zone, we applied a strike?slip faulting stress, where shmax > sv > shmin. Upon visual inspection of limited stress magnitude data from the Walker Lane and Eastern California Shear zone, we chose values such that SHmin/SHmax = .46 and Shmin/Sv= .527 representative of the region. Results: The results of our slip and dilation tendency analysis are shown in Figures 4 (dilation tendency), 5 (slip tendency) and 6 (slip tendency + dilation tendency). Shmin varies from northwest to east?west trending throughout much of the Great Basin. As such, north? to northeast?striking faults have the highest tendency to slip and to dilate, depending on the local trend of shmin. These results provide a first order filter on faults and fault systems in the Great Basin, affording focusing of local?scale exploration efforts for blind or hidden geothermal resources.

James E. Faulds

2013-09-30

231

Dynamics of Slip Fronts at Frictional Interfaces: Analysis of Slip Precursors  

NASA Astrophysics Data System (ADS)

The transition from sticking to sliding of frictional interfaces is a phenomenon of importance for many physical systems in nature as well as in engineering. This transition is marked by the occurrence of local slip events, often called precursors, which appear before the global sliding is observed. Such precursors to global sliding may occur on segments of geophysical faults subject to non uniform shear loading, for example a fault segment located between a locked and steadily slipping region. Sequences of small earthquakes (foreshocks) of identical seismic characteristics have been observed preceding large earthquakes in several regions. The links between the occurrence of these foreshocks and the nucleation process of large earthquakes remains elusive, but has large implications for earthquake prediction and risk assessment. These precursors have been studied experimentally by Rubinstein et al. [2007]. However, the experimental study of interfaces is challenging due to difficulties to access information at the interface. Therefore, numerical simulations are needed in order to give additional information for accurate analysis. First attempts have been undertaken using simple spring-block systems [Maegawa et al. 2010, Tromborg et al. 2011]. In this study however, we use the finite-element method, which allows us to represent accurately the continuum character of the system, and to investigate the onset and evolution of sliding at a frictional interface. The studied setup is similar to the experimental setup used by Ben-David et al. [2010]. It consists of a block of viscoelastic material in contact with a rigid body. A velocity-weakening friction law controls the friction at the interface. Special care is taken to apply appropriate regularization and viscosity in the simulation. We apply a shear load to the block, either on the top surface of the block or on one side. In both cases, the resulting shear tractions at the interface are non-uniform. The stress distribution presents a high concentration close to the edge when the load is applied on the side. Applying a non-uniform shear loading, we observe a sequence of slip precursors, which initiate at shear levels well below the global static friction threshold. These precursors stop before propagating over the entire interface, and their length increase with increasing shear force. Our results are consistent with previous experimental observations [Rubinstein et al., 2007]. We analyze the relation between the applied load, the precursors length, and the evolution of stresses at the interface.

Radiguet, M.; Kammer, D. S.; Molinari, J.

2012-12-01

232

Duration of slip-resistant shoe usage and the rate of slipping in limited-service restaurants: results from a prospective and crossover study.  

PubMed

Several studies have indicated that slip-resistant shoes may have a positive effect on reducing the risk of slips and falls, a leading cause of injury at work. Few studies, however, have examined how duration of shoe usage affects their slip-resistance properties. This study examined the association between the duration of slip-resistant shoes usage and the self-reported rate of slipping in limited-service restaurant workers. A total of 475 workers from 36 limited-service restaurants in the USA were recruited to participate in a 12-week prospective study of workplace slipping. Of the 475 participants, 83 reported changing to a new pair of shoes at least once during the 12-week follow-up. The results show that slip-resistant shoes worn for less than six months were moderately more effective than those worn for more than six months. Changing to a new pair of shoes among those wearing slip-resistant shoes at baseline was associated with a 55% reduction in the rate of slipping (RR = 0.45, 95% CI = 0.23-0.89). Further research is needed to develop criteria for the replacement of slip-resistant shoes. Practitioner Summary: The duration of usage impacts the slip-resistance properties of slip-resistant shoes. Slip-resistant shoes worn for less than six months were moderately more effective in reducing slips than slip-resistant shoes worn for more than six months. Shoe use policies should not only encourage or require their use but also include guidance on replacing slip-resistant shoes at regular intervals. PMID:25205136

Verma, Santosh K; Zhao, Zhe; Courtney, Theodore K; Chang, Wen-Ruey; Lombardi, David A; Huang, Yueng-Hsiang; Brennan, Melanye J; Perry, Melissa J

2014-12-01

233

Nucleation and triggering of earthquake slip: effect of periodic stresses  

USGS Publications Warehouse

Results of stability analyses for spring and slider systems, with state variable constitutive properties, are applied to slip on embedded fault patches. Unstable slip may nucleate only if the slipping patch exceeds some minimum size. Subsequent to the onset of instability the earthquake slip may propagate well beyond the patch. It is proposed that the seismicity of a volume of the earth's crust is determined by the distribution of initial conditions on the population of fault patches that nucleate earthquake slip, and the loading history acting upon the volume. Patches with constitutive properties inferred from laboratory experiments are characterized by an interval of self-driven accelerating slip prior to instability, if initial stress exceeds a minimum threshold. This delayed instability of the patches provides an explanation for the occurrence of aftershocks and foreshocks including decay of earthquake rates by time-1. A population of patches subjected to loading with a periodic component results in periodic variation of the rate of occurrence of instabilities. The change of the rate of seismicity for a sinusoidal load is proportional to the amplitude of the periodic stress component and inversely proportional to both the normal stress acting on the fault patches and the constitutive parameter, A1, that controls the direct velocity dependence of fault slip. Values of A1 representative of laboratory experiments indicate that in a homogeneous crust, correlation of earthquake rates with earth tides should not be detectable at normal stresses in excess of about 8 MPa. Correlation of earthquakes with tides at higher normal stresses can be explained if there exist inhomogeneities that locally amplify the magnitude of the tidal stresses. Such amplification might occur near magma chambers or other soft inclusions in the crust and possibly near the ends of creeping fault segments if the creep or afterslip rates vary in response to tides. Observations of seismicity rate variations associated with seasonal fluctuations of reservoir levels appear to be consistent with the model. ?? 1987.

Dieterich, J.H.

1987-01-01

234

A comparison of slip rate, recurrence interval, and slip per event on several well-characterized faults (Invited)  

NASA Astrophysics Data System (ADS)

Rapid growth in the application of LiDAR and other modern geodetic techniques has led to an explosion in the number of micro-geomorphic offsets along faults that can be interpreted as displacement in one or several earthquakes. As a result of this new data there are an increasing number of places along faults for which data are available for the slip rate (based on the dated offset of a feature that is old enough to average out the seismic cycle), recurrence interval (based on a representative number of dated paleo-earthquakes), and slip per event (based on an adequate sample of micro-geomorphic or 3D-excavated offsets). Because these three datasets are largely independent, but related by accumulation and release of strain across the fault, comparing them can provide insight into how faults balance size and frequency of earthquakes. We discuss several examples of faults with closely co-located slip rate, recurrence interval, and slip per event data, including the Ana River fault, a small normal fault in Central Oregon, and portions of the San Andreas fault, the principal plate boundary fault in California. The Ana River fault offsets more than 11 Pleistocene shorelines different amounts that we have measured using a combination of LiDAR, ground-based surveying, and a DEM generated from a USGS topographic map with 5 foot contours. The ages of ~10 paleo-earthquakes are determined from trenches and other exposures into deep-water lacustrine deposits that contain ~50 dated volcanic ashes. The long-term slip rate, 0.05 mm/yr, is known from the total offset of dated late Pliocene basalts. We also use new data from the Santa Cruz segment of the northern San Andreas fault (NSAF) and the southern San Andreas fault (SSAF: Parkfield to Bombay Beach). On the NSAF, earthquakes in 1838, 1890, and 1906 have a total slip of 4 - 6 m while the slip rate (17 mm/yr) suggests it would take 2 - 3 centuries to accumulate this much strain. Data for the SSAF, which have recently been compiled for UCERF-3, include 12 sites with recurrence intervals, hundreds of micro-geomorphic offsets, including at least 7 places with closely-spaced progressively larger offsets that allow one to estimate the average slip per event, and slip rate estimates that vary from about 34 to 12 mm/yr, decreasing from Parkfield to San Gorgonio Pass and then increasing to the southern end of the SSAF. In general the 3 types of data are reasonably consistent (i.e. slip rate (mm/yr) = slip per event (mm) X recurrence interval (1/yr)). Recurrence intervals seem to be more variable than displacements, although displacement variability may be biased by difficulty resolving small offsets with geomorphic markers. Assuming slip rate is constant through time, in places where (or periods of time when) there are inconsistencies between the three parameters it appears to be due to the intervals between earthquakes varying more than displacements, i.e. short intervals are not associated with small enough displacements and long intervals do not yield unusually large displacements. Similarly, as the SSAF changes slip rate along strike the recurrence interval varies more than the size of slip events.

Weldon, R. J.; Lippoldt, R. C.; Scharer, K.; Streig, A. R.; Langridge, R. M.; Madugo, C. M.; Biasi, G. P.; Dawson, T. E.

2013-12-01

235

Intense interface seismicity triggered by a shallow slow-slip event in the Central-Ecuador subduction zone  

NASA Astrophysics Data System (ADS)

Slow slip events (SSE) are more often associated with non-volcanic tremors than with classical earthquakes. We document here a deformation episode where an abundant seismicity has been triggered by an SSE. In August 2010, a one week long slow-slip event (SSE) with an equivalent moment magnitude of 6.0-6.3 occurred below La Plata Island (Ecuador), south of the rupture area of the Mw=8.8 1906 megathrust earthquake. GPS data reveal that the SSE occurred at a depth of about 10km, within the downdip part of a shallow (<15km), isolated, locked patch along the subduction interface. The availability of both broad-band seismometer and continuous geodetic station located at the La Plata Island, 10km above the SSE, enables a careful analysis of the relationships between slow and rapid processes of stress release along the subduction interface. During the slow slip sequence, the seismic data shows a sharp increase of the local seismicity (see Figure below), with more than 650 earthquakes detected, among which 50 have a moment magnitude between 1.8 and 4.1. However, the cumulative moment released through earthquakes accounts at most for 0.2% of the total moment release estimated from GPS displacements. Most of the largest earthquakes are located along or very close to the subduction interface with focal mechanism consistent with the relative plate motion. These largest events appear to occur randomly during the slow slip sequence, which further evidence that the seismicity is driven by the stress fluctuations related to aseismic slip. A large part of the seismic events observed during the SSE is organized into families of repeating earthquakes, which may indicate a progressive rupture within small locked patches. Recent observations show that this zone of the subduction is prone to SSEs, as evidenced by a new SSE observed in January 2013. These findings offer an a posteriori interpretation of the seismogenesis in the Central-Ecuador subduction zone, where intense seismic swarms have been regularly observed (1977, 1998, 2002, 2005). These swarms have likely been triggered by large magnitude slow-slip events. Joint observations of the geodetic displacement and of the seismicity rate at La Plata Island (ISPT station) during the 2010 SSE. (Red) Number of seismic events detected over 2 hours sessions for an LTA/STA ratio higher than 6.0. (Grey dots) East displacement recorded by the GPS station, calculated every 6 hours.

Vallee, M.; Nocquet, J.; Battaglia, J.; Font, Y.; Segovia, M.; Regnier, M. M.; Mothes, P. A.; Jarrín, P.; Cisneros, D.; Vaca, S.; Yepes, H. A.; Martin, X.; Béthoux, N.; Chlieh, M.

2013-12-01

236

Granular and semi-brittle descriptions of slip and creep  

NASA Astrophysics Data System (ADS)

Crustal deformation generates a wide range of creep and slip behaviors. Coseismic fault slip, aseismic creep, long-term strain transients, and slow-slip events all accommodate a great deal of tectonic strain and cause or contribute to destructive geohazards. Moreover, all have different time scales and exhibit differing degrees of periodicity. The dynamic frictional response of fault surfaces and fault rocks to slip may control a great deal of crustal slip and creep behaviors. Such is also the case for effective stress changes through fluid-pressure fluctuation and remote triggering. Yet, few existing friction and effective-stress models address the heterogeneity, range of metamorphic conditions, and range of deformational time scales that characterize natural shear zones. A useful framework for addressing this geological diversity is to treat natural shear zones as granular media. Physical experiments using analog materials provide some insight into such an approach. Shear zones of dry, granular materials produce stick-slip events via jamming phenomena, including influencing the periodicity and duration of events. When added to such granular mixtures, viscous materials enhance localization and smooth stick-slip events. Though such experimental approaches are difficult to simulate numerically, analytical and numerical solutions for fracture propagation into semi-brittle media can produce strain transients with a wide range of durations and recurrence intervals. A good example of how to use these concepts is in the characterization of possible slip behaviors for now-exhumed mid-crustal shear zones. Such shear zones tend to have deformed via predominantly viscous crystal plastic mechanisms, yet their creep behavior may well have produced strain transients including episodic tremor and slip. Fracture propagation into creeping media comprising mixtures of strong and weak materials could explain the generation of such phenomena. Geological observations of strong mafic lenses within weaker quartz-rich gneiss, cut by syntectonic quartz veins, are widely observed structural records of such behavior. Extending this analysis into the upper crust, however, will require a more complete framework for describing the strength of granular materials in the crust.

Hayman, N. W.; Lavier, L. L.

2013-12-01

237

How well do surface offsets represent earthquake slip at depth?  

NASA Astrophysics Data System (ADS)

Earthquake ruptures originate in the base of the unstable velocity-weakening part of the seismogenic layer and propagate into the velocity-strengthening upper stability region. Resulting deformation is transmitted to Earth's topography by driving slip along faults and block motions. Two factors affect this process: (1) the three-dimensional geometrical complexity and roughness of fault segments that control rupture continuity, and (2) spatiotemporal strength variations of the seismogenic layer that control the mechanical behavior of the fault zone. Earth's topography preserves evidence of past earthquakes as localized strain along fault scarps and fractures or distributed strain via off-fault folding and warping. These structures may be modified postseismically via afterslip and geomorphically degraded years to decades after rupturing. We investigate how well displaced geomorphic markers represent coseismic slip as it is transmitted from the seismogenic layer through to Earth's surface. We use lidar-derived measurements of single- and multi-event offset geomorphic markers to provide surface constraints on surface slip distributions of past earthquakes. Using FIMozFric, a numerical earthquake simulator that incorporates complex geomechanical properties of the seismogenic layer, we test various fault structural configurations and mechanical properties of the 2010 El Mayor-Cucupah earthquake. Initial simulations investigate the effect of simple fault complexities, such as stepovers and bends, on surface offsets using a simple two-layered seismogenic zone geometry. We then explore the effect of varying the mechanical complexity of the seismogenic zone by varying the relative geometries of the velocity-weakening and velocity-strengthening portions, thus simulating the variable mechanical properties of the upper lithosphere through which earthquakes propagate. Our results show that the geometrical complexity of faults controls the distribution of surface slip. More importantly, our simulations demonstrate that the mechanical configuration of the seismogenic layer within which faults are embedded affects how slip is distributed along single fault geometries and partitioned across zones with multiple fault strands. Variability in the depth of the velocity-weakening/velocity-strengthening interface appears to control the magnitude of single-event surface slip. These results shed light on the ability to confidently interpret paleoseismic and topographic records of the magnitude and recurrence of earthquakes, especially in relation to slip in a single earthquake. This is an especially important insight for efforts such as the Uniform California Earthquake Rupture Forecast (UCERF3) that aim to use lidar-derived slip in the most recent event as geologic constraints for expected slip magnitudes of future earthquakes but without accounting for the detailed lithology and structure of a fault zone.

Haddad, D. E.; Zielke, O.; Arrowsmith, R.

2013-12-01

238

Scaling analysis for the investigation of slip mechanisms in nanofluids  

NASA Astrophysics Data System (ADS)

The primary objective of this study is to investigate the effect of slip mechanisms in nanofluids through scaling analysis. The role of nanoparticle slip mechanisms in both water- and ethylene glycol-based nanofluids is analyzed by considering shape, size, concentration, and temperature of the nanoparticles. From the scaling analysis, it is found that all of the slip mechanisms are dominant in particles of cylindrical shape as compared to that of spherical and sheet particles. The magnitudes of slip mechanisms are found to be higher for particles of size between 10 and 80 nm. The Brownian force is found to dominate in smaller particles below 10 nm and also at smaller volume fraction. However, the drag force is found to dominate in smaller particles below 10 nm and at higher volume fraction. The effect of thermophoresis and Magnus forces is found to increase with the particle size and concentration. In terms of time scales, the Brownian and gravity forces act considerably over a longer duration than the other forces. For copper-water-based nanofluid, the effective contribution of slip mechanisms leads to a heat transfer augmentation which is approximately 36% over that of the base fluid. The drag and gravity forces tend to reduce the Nusselt number of the nanofluid while the other forces tend to enhance it.

Savithiri, S.; Pattamatta, Arvind; Das, Sarit K.

2011-07-01

239

Scaling analysis for the investigation of slip mechanisms in nanofluids  

PubMed Central

The primary objective of this study is to investigate the effect of slip mechanisms in nanofluids through scaling analysis. The role of nanoparticle slip mechanisms in both water- and ethylene glycol-based nanofluids is analyzed by considering shape, size, concentration, and temperature of the nanoparticles. From the scaling analysis, it is found that all of the slip mechanisms are dominant in particles of cylindrical shape as compared to that of spherical and sheet particles. The magnitudes of slip mechanisms are found to be higher for particles of size between 10 and 80 nm. The Brownian force is found to dominate in smaller particles below 10 nm and also at smaller volume fraction. However, the drag force is found to dominate in smaller particles below 10 nm and at higher volume fraction. The effect of thermophoresis and Magnus forces is found to increase with the particle size and concentration. In terms of time scales, the Brownian and gravity forces act considerably over a longer duration than the other forces. For copper-water-based nanofluid, the effective contribution of slip mechanisms leads to a heat transfer augmentation which is approximately 36% over that of the base fluid. The drag and gravity forces tend to reduce the Nusselt number of the nanofluid while the other forces tend to enhance it. PMID:21791036

2011-01-01

240

Formation of Quantum Phase Slip Pairs in Superconducting Nanowires  

E-print Network

Macroscopic quantum tunneling (MQT) is a fundamental phenomenon of quantum mechanics, related to an actively debated topic of the quantum-to-classical transition. In addition, implementation of quantum computing schemes, involving qubits, is often dependent on our ability to realize an MQT process, as well as on the protection of the resulting quantum state against decoherence. Decoherence in qubits can be reduced by means of topological protection, e.g., by exploiting various parity effects. In particular, the double-phase-slip effect can provide such protection for superconducting qubits. Here, we report direct observation of quantum double phase slips in thin-wire superconducting loops. We show that, in addition to conventional single phase slips, changing superconducting order parameter phase by $2\\pi$, there are quantum transitions changing the phase by $4\\pi$. Quantum double phase slips represent a synchronized occurrence of two macroscopic quantum tunneling events, i.e., the cotunneling. We demonstrate the existence of a striking regime in which double phase slips are exponentially more probable than single ones.

Andrey Belkin; Maxim Belkin; Victor Vakaryuk; Sergei Khlebnikov; Alexey Bezryadin

2014-06-19

241

Path Following with Slip Compensation for a Mars Rover  

NASA Technical Reports Server (NTRS)

A software system for autonomous operation of a Mars rover is composed of several key algorithms that enable the rover to accurately follow a designated path, compensate for slippage of its wheels on terrain, and reach intended goals. The techniques implemented by the algorithms are visual odometry, full vehicle kinematics, a Kalman filter, and path following with slip compensation. The visual-odometry algorithm tracks distinctive scene features in stereo imagery to estimate rover motion between successively acquired stereo image pairs, by use of a maximum-likelihood motion-estimation algorithm. The full-vehicle kinematics algorithm estimates motion, with a no-slip assumption, from measured wheel rates, steering angles, and angles of rockers and bogies in the rover suspension system. The Kalman filter merges data from an inertial measurement unit (IMU) and the visual-odometry algorithm. The merged estimate is then compared to the kinematic estimate to determine whether and how much slippage has occurred. The kinematic estimate is used to complement the Kalman-filter estimate if no statistically significant slippage has occurred. If slippage has occurred, then a slip vector is calculated by subtracting the current Kalman filter estimate from the kinematic estimate. This slip vector is then used, in conjunction with the inverse kinematics, to determine the wheel velocities and steering angles needed to compensate for slip and follow the desired path.

Helmick, Daniel; Cheng, Yang; Clouse, Daniel; Matthies, Larry; Roumeliotis, Stergios

2005-01-01

242

Research on slip resistance measurements--a new challenge.  

PubMed

Slips, trips and falls are one of the most common causes of injuries and fatalities in the general community and industry. The control of such incidents involves a complex array of factors including the characteristics of each individual's footwear and gait dynamics, walking and working surfaces, and environmental conditions. Notwithstanding this complexity, slip resistance properties have been widely measured as a form of coefficient of friction (COF) index at the sliding interface between the shoes and floors. Since the COF measurements were commonly adopted to evaluate slip potentials, it has been found that there were controversies in the interpretation of COF measurement results. This study, therefore, was principally focused on broadening the knowledge base and developing new ideas on which improvements in the validity and reliability of slip resistance measurements might be made. To achieve this goal, crucial problems on the current concept of slip resistance measurement were extensively analysed by a tribological point of view where principle understanding of the shoe-floor friction and wear phenomena could be made. Based on this approach, new theoretical models were suggested. PMID:18270452

Kim, In-Ju; Nagata, Hisao

2008-01-01

243

Slip stream apparatus and method for treating water in a circulating water system  

DOEpatents

An apparatus (10) for treating water in a circulating water system (12) t has a cooling water basin (14) includes a slip stream conduit (16) in flow communication with the circulating water system (12), a source (36) of acid solution in flow communication with the slip stream conduit (16), and a decarbonator (58) in flow communication with the slip stream conduit (16) and the cooling water basin (14). In use, a slip stream of circulating water is drawn from the circulating water system (12) into the slip stream conduit (16) of the apparatus (10). The slip stream pH is lowered by contact with an acid solution provided from the source (36) thereof. The slip stream is then passed through a decarbonator (58) to form a treated slip stream, and the treated slip stream is returned to the cooling water basin (14).

Cleveland, Joe R. (West Hills, CA)

1997-01-01

244

Can observations of earthquake scaling constrain slip weakening?  

NASA Astrophysics Data System (ADS)

We use observations of earthquake source parameters over a wide magnitude range (MW~ 0-7) to place constraints on constitutive fault weakening. The data suggest a scale dependence of apparent stress and stress drop; both may increase slightly with earthquake size. We show that this scale dependence need not imply any difference in fault zone properties for different sized earthquakes. We select 30 earthquakes well-recorded at 2.5 km depth at Cajon Pass, California. We use individual and empirical Green's function spectral analysis to improve the resolution of source parameters, including static stress drop (??) and total slip (S). We also measure radiated energy ES. We compare the Cajon Pass results with those from larger California earthquakes including aftershocks of the 1994 Northridge earthquake and confirm the results of Abercrombie (1995): ?ES/M0<slip, then G'=G, the fracture energy in a slip-weakening interpretation of dissipation. We find that G' increases with S, from ~103 J m-2 at S= 1 mm (M1 earthquakes) to 106-107 J m-2 at S= 1 m (M6). We tentatively interpret these results within slip-weakening theory, assuming G'~G. We consider the common assumption of a linear decrease of strength from the yield stress (?p) with slip (s), up to a slip Dc. In this case, if either Dc, or more generally (?p-?d) Dc, increases with the final slip S we can match the observations, but this implies the unlikely result that the early weakening behaviour of the fault depends on the ultimate slip that the fault will sustain. We also find that a single slip-weakening function ?F(s) is able to match the observations, requiring no such correlation. Fitting G' over S= 0.2 mm to 0.2 m with G'~S1+n, we find n~ 0.3, implying a strength drop from peak ?p-?F(S) ~Sn. This model also implies that slip weakening continues beyond the final slip S of typical earthquakes smaller than ~M6, and that the total strength drop ?p-?d for large earthquakes is typically >20 MPa, larger than ??. The latter suggests that on average a fault is initially stressed below the peak strength, requiring stress concentration at the rupture front to propagate slipping.

Abercrombie, Rachel E.; Rice, James R.

2005-08-01

245

Small Earthquake Scaling Revisited: Can it Constrain Slip Weakening?  

NASA Astrophysics Data System (ADS)

We select 29 earthquakes well-recorded at 2.5 km depth at Cajon Pass (Abercrombie, 1995), including some colocated events. We compare spectral and time domain inferences of the source dimension to estimate final slip s and static stress drop ? ? . We measure radiated energy Es by integration of the velocity-squared spectra using simple fits to extend the bandwidth outside the observed range to ensure we do not lose significant energy due to instrumental limits. (The Es estimates of Abercrombie (1995) for earthquakes Mo < 5x 1011 Nm are selectively biased to small stress drops, but otherwise the results are similar.) We compare the CJP results with those from larger California earthquakes including Northridge aftershocks and confirm Abercrombie (1995): for the smallest earthquakes, ? Es/M_o << ? ? (where ? = rigidity) and Es/M_o increases more rapidly than ? ? as Mo (and also s) increases. To interpret this we define a quantity G' = [? ? - 2? Es/M_o]s/2 which is the total energy dissipation in friction and fracture minus ? s s, where ? s is the final static stress. If ? s = ? d, the dynamic shear strength during the last increments of seismic slip, then G' = G, the fracture energy in a slip-weakening interpretation of dissipation, with ? d then identified as the residual shear strength of Palmer and Rice (1973). Otherwise G' = G + (? d - ? s)s. We find that G' increases with s, from ~103 J/m2 at s = 1 mm (M1 events) to 106 to 107 J/m2 at s = 1 m (M6). An increasing rupture velocity with Mo cannot explain these results because it would imply unreasonably high ? ? for the small earthquakes. We tentatively interpret these results within slip-weakening theory, assuming G' ? G (i.e., ? s ? ? d). One explanation for these observations within the often assumed linear decrease of strength with slip, up to a slip Dc, is that either Dc, or the peak to residual strength drop ? p - ? d, or more generally (? p - ? d) Dc, varies in proportion to the final slip s. This can match the observations, but implies the unlikely result that the weakening behavior of the fault depends on the final size of the earthquake. We also find that a single slip-weakening function ? (s) is able to match the observations, requiring no such correlation. Fitting G over s = 1 mm to 0.5 m with G ~ s{1 + n}, we find n ~ 0.1 to 0.2. We show that this implies a strength drop from peak ? p - ? (s) ~ sn. This model also implies that the slip weakening continues beyond the final slip s of typical events smaller than ~M6, and that the total strength drop ? p - ? d for large earthquakes is typically > 20 MPa and notably larger than ? ? . The latter suggests that on average the fault is initially stressed well below the peak strength, requiring stress concentration at the rupture front to propagate slipping. Other interpretations need to be explored outside the context of slip-weakening and allowing for dynamic over/undershoot.

Abercrombie, R. E.; Rice, J. R.

2001-12-01

246

Slip-boundary equations for multicomponent nonequilibrium airflow  

NASA Technical Reports Server (NTRS)

Equations are presented for the surface-slip (or jump) values of species concentration, pressure, velocity, and temperature in the low Reynolds number, high-altitude flight regime of a space vehicle. These are obtained from closed-form solutions of the mass, momentum, and energy flux equations by using the Chapman-Enskog velocity distribution function. This function represents a solution of the Boltzmann equation in the Navier-Stokes approximation. The analysis, obtained for nonequilibrium multicomponent airflow, includes the finite-rare surface catalytic recombination and changes in the internal energy during reflection from the surface. Expressions for the various slip quantities have been obtained in a form which can readily be employed in flow-field computations. A consistent set of equations is provided for multicomponent and binary mixtures and single-species gas. An expression is also provided for the finite-rate species-concentration boundary condition for a multicomponent mixture in the absence of slip.

Gupta, R. N.; Scott, C. D.; Moss, J. N.

1985-01-01

247

Surface-slip equations for multicomponent nonequilibrium air flow  

NASA Technical Reports Server (NTRS)

Equations are presented for the surface-slip (or jump) values of species concentration, pressure, velocity, and temperature in the low-Reynolds number, high-altitude flight regime of a space vehicle. The equations are obtained from closed form solutions of the mass, momentum, and energy flux equations using the Chapman-Enskog velocity distribution function. This function represents a solution of the Boltzmann equation in the Navier-Stokes approximation. The analysis, obtained for nonequilibrium multicomponent air flow, includes the finite-rate surface catalytic recombination and changes in the internal energy during reflection from the surface. Expressions for the various slip quantities were obtained in a form which can be employed in flowfield computations. A consistent set of equations is provided for multicomponent, binary, and single species mixtures. Expression is also provided for the finite-rate, species-concentration boundary condition for a multicomponent mixture in absence of slip.

Gupta, R. N.; Scott, C. D.; Moss, J. N.

1985-01-01

248

Surface-slip equations for multicomponent, nonequilibrium air flow  

NASA Technical Reports Server (NTRS)

Equations are presented for the surface slip (or jump) values of species concentration, pressure, velocity, and temperature in the low-Reynolds-number, high-altitude flight regime of a space vehicle. These are obtained from closed-form solutions of the mass, momentum, and energy flux equations using the Chapman-Enskog velocity distribution function. This function represents a solution of the Boltzmann equation in the Navier-Stokes approximation. The analysis, obtained for nonequilibrium multicomponent air flow, includes the finite-rate surface catalytic recombination and changes in the internal energy during reflection from the surface. Expressions for the various slip quantities have been obtained in a form which can readily be employed in flow-field computations. A consistent set of equations is provided for multicomponent, binary, and single species mixtures. Expression is also provided for the finite-rate species-concentration boundary condition for a multicomponent mixture in absence of slip.

Gupta, Roop N.; Scott, Carl D.; Moss, James N.; Goglia, Gene

1985-01-01

249

ETS and tidal stressing: Fault weakening after main slip pulse  

NASA Astrophysics Data System (ADS)

Time-varying stresses from solid Earth tides and ocean loading influence slow slip (Hawthorne and Rubin, 2010) and, consequently, the frequency of occurrence and intensity of tremor during ETS episodes (Rubinstein et al., 2008). This relationship can illuminate changes in the mechanical response of the rupture surfaces(s) during slip in ETS. I compare the influence of tidal loading when and after the propagating ETS slip front (estimated by tremor density in time) ruptures the fault at a given spot. Using estimates of slip fronts that I derived from tremor locations, I divide ETS tremor into two groups: that occurring within a day of the start of the inferred slip front and that occurring over several days thereafter. The tremor catalog used contains 50K waveform cross-correlation locations of tremor in 7 large ETS in northern Cascadia between 2005 and 2012. I calculate normal, shear and volumetric stresses due to the Earth and ocean tides at numerous locations on the inferred rupture plane of the ETS following the method of Hawthorne and Rubin (2010). The Coulomb stress increment at each tremor time and location is compared with tremor occurrence for the two groups of tremor. Unreasonable results appear if the effective frictional coefficient mu > 0.2, and results are most 'reasonable' when mu is very near or equal to zero. Following passage of the main slip pulse, tremor generation is notably more sensitive to tidal stressing. One kPa of encouraging tidal Coulomb stress boosts the occurrence of tremor after the main slip pulse by about 50% above the average value, while the same amount of discouraging stress decreases the occurrence of such tremor by a similar factor. The greater the encouraging or discouraging stress, the greater the effect. In contrast, tremor in the main slip pulse is much less affected by positive or negative tidal stresses. I interpret the greater sensitivity to tidal stressing of the tremor after the main slip pulse as a measure of the weakening of the fault plane following its initial rupture. Considering up- and down-dip sensitivities to tidal stress, tremor generation on the up-dip region is affected roughly 50% more by both positive and negative tidal stresses than tremor down-dip. Furthermore, for the down-dip tremor, there is less contrast in sensitivity to stress between the tremor at the main slip front and the later tremor, i.e., the fault downdip is both less sensitive to tidal stress and weakens less due to the rupture. These results are consistent with the timing and geometry of Rapid Tremor Reversals, which also indicate weakening of the fault after the main slip front has passed through a region (Houston et al., 2011). RTRs occur on updip parts of the fault, after the main slip front, and at times of encouraging tidal stress (Thomas et al., 2013).

Houston, H.

2013-12-01

250

The Effect of Patterned Slip on Micro and Nanofluidic Flows  

E-print Network

We consider the flow of a Newtonian fluid in a nano or microchannel with walls that have patterned variations in slip length. We formulate a set of equations to describe the effects on an incompressible Newtonian flow of small variations in slip, and solve these equations for slow flows. We test these equations using molecular dynamics simulations of flow between two walls which have patterned variations in wettability. Good qualitative agreement and a reasonable degree of quantitative agreement is found between the theory and the molecular dynamics simulations. The results of both analyses show that patterned wettability can be used to induce complex variations in flow. Finally we discuss the implications of our results for the design of microfluidic mixers using slip.

Hendy, S C; Burnell, J

2005-01-01

251

Cretaceous sinistral strike slip along Nacimiento fault in Coastal California  

SciTech Connect

The San Andreas and Nacimiento faults of coastal California both separate granitic and metamorphic basement rocks of the Salinian block from partly coeval but contrasting Mesozoic terranes underlain by the Franciscan subduction complex. By analogy with Neogene dextral strike slip along the San Andreas fault, Cretaceous sinistral strike slip can be inferred along the Nacimiento fault in preference to hypotheses for tectonic erosion during subduction or for dextral strike slip of unspecified amount. The similar Mesozoic terranes that now lie east and west of the Salinian block were then adjacent to one another west of the Sierra Nevada block. Available paleomagnetic data neither support nor preclude the reconstruction, but additional work together with future detailed lithotectonic comparisons potentially can confirm or refute the hypothesis it represents. A correct interpretation of the Nacimiento fault is important for understanding the overall tectonic framework of petroliferous basins both onshore and offshore in coastal California.

Dickinson, W.R.

1983-04-01

252

Shock slip-relations for thermal and chemical nonequilibrium flows  

NASA Astrophysics Data System (ADS)

This paper appears to be the first where the multi-temperature shock slip-relations for the thermal and chemical nonequilibrium flows are derived. The derivation is based on analysis of the influences of thermal nonequilibrium and viscous effects on the mass, momentum and emergy flux balance relations at the shock wave. When the relaxation times for all internal energy modes tend to zero, the multi-tmperature shock slip-relations are converted into single-temperature ones for thermal equilibrium flows. The present results can be applied to flow over vehicles of different geometries with or without angles of attack. In addition, the present single-temperature shock slip-relations are compared with those in the literature, and some defects and limitations in the latter are clarified.

Jinrong, Tang

1996-05-01

253

Reduced Aftershock Productivity in Regions with Known Slow Slip Events  

NASA Astrophysics Data System (ADS)

Reduced aftershock activity has been observed in areas with high rates of aseismic slip, such as transform fault zones and some subduction zones. Fault conditions that could explain both of these observations include a low effective normal stress regime and/or a high temperature, semi-brittle/plastic rheology. To further investigate the possible connection between areas of aseismic slip and reduced aftershock productivity, we compared the mainshock-aftershock sequences in subduction zones where aseismic slip transients have been observed to those of adjacent (along-strike) regions where no slow slip events have been detected. Using the Advanced National Seismic System (ANSS) catalog, we counted aftershocks that occurred within 100 km and 14 days of 112 M>=5.0 slab earthquake mainshocks from January 1980 - July 2013, including 90 since January 2000, inside observed regions of detected slow slip: south central Alaska, Cascadia, the Nicoya Peninsula (Costa Rica), Guerrero (Mexico), and the North Island of New Zealand. We also compiled aftershock counts from 97 mainshocks from areas adjacent to each of these regions using the same criteria and over the same time interval. Preliminary analysis of these two datasets shows an aftershock triggering exponent (alpha in the ETAS model) of approximately 0.8, consistent with previous studies of aftershocks in a variety of tectonic settings. Aftershock productivity for both datasets is less than that of continental earthquakes. Contrasting the two datasets, aftershock productivity inside slow slip regions is lower than in adjacent areas along the same subduction zone and is comparable to that of mid-ocean ridge transform faults.

Collins, G.; Mina, A.; Richardson, E.; McGuire, J. J.

2013-12-01

254

Possible Stick-Slip Mechanism for Whillans Ice Stream  

NASA Technical Reports Server (NTRS)

Tidally-induced stick-slip motion in the mouth of Whillans Ice Stream provides a unique natural experiment in ice-stream response behavior and fiom which we might learn a great deal about subglacial till properties and sub-ice-stream conditions. At the IGS Symposium on Fast Glacier Flow (Yakutat, 2002), we reported our observations of stick- slip motion and demonstrated its synchronicity with tidal forcing. Recently, we have completed additional processing of our GPS data in differential mode. It reveals more details of the stick-slip events and illustrates that within 30 seconds, the temporal interval of our data, the ice stream accelerates to a speed corresponding to a completely lubricated bed. While details of individual events vary, there seems to be strong evidence of an elastic rebound on the time scale of one hour following most events. This suggests the event involves the release of stored elastic strain energy in the ice. The similar displacements of events suggest further that till or subglacial hydrologic properties limit the amount of elastic strain released in any single event. We follow a line of reasoning that dilatant strengthening limits the slip displacement and present model of the stick-slip process. To match the observed delay between the peak ocean tide and stick-slip events, our model includes a propagating pressure wave in the subglacial hydrologic system between the grounding line, where the rising tide first increases the subglacial water pressure and regions upstream where stored elastic strain increases the basal shear stress. This high-tide event is released when the increased water pressure reaches the region of increased shear stress. Dilatant strengthening stops the event by increasing pore volume and lowering the water pressure. Following this event, falling tide increases the normal forces, compresses the till and increases pore pressure again, leading to the second falling-tide event we observe every tidal cycle.

Bindschadler, Robert; King, Matt; Vornberger, Patricia

2003-01-01

255

Possible Stick-Slip Mechanism for Whillans Ice Stream  

NASA Technical Reports Server (NTRS)

Tidally-induced stick-slip motion in the mouth of Whillans Ice Stream provides a unique natural experiment in ice-stream response behavior and from which we might learn a great deal about subglacial till properties and sub-ice-stream conditions. At the IGS Symposium on Fast Glacier Flow (Yakutat, 2002), we reported our observations of stick- slip motion and demonstrated its synchronicity with tidal forcing. Recently, we have completed additional processing of our GPS data in differential mode. It reveals more details of the stick-slip events and illustrates that within 30 seconds, the temporal interval of our data, the ice stream accelerates to a speed corresponding to a completely lubricated bed. While details of individual events vary, there seems to be strong evidence of an elastic rebound on the time scale of one hour following most events. This suggests the event involves the release of stored elastic strain energy in the ice. The similar displacements of events suggest further that till or subglacial hydrologic properties limit the amount of elastic strain released in any single event. We follow a line of reasoning that dilatant strengthening limits the slip displacement and present model of the stick-slip process. To match the observed delay between the peak ocean tide and stick-slip events, our model includes a propagating pressure wave in the subglacial hydrologic system between the grounding line, where the rising tide first increases the subglacial water pressure and regions upstream where stored elastic strain increases the basal shear stress. This high-tide event is released when the increased water pressure reaches the region of increased shear stress. Dilatant strengthening stops the event by increasing pore volume and lowering the water pressure. Following this event, falling tide increases the normal forces, compresses the till and increases pore pressure again, leading to the second falling-tide event we observe every tidal cycle.

Bindschadler, Robert; King, Matt; Vornberger, Patricia

2003-01-01

256

Stick-slip instability for viscous fingering in a gel  

NASA Astrophysics Data System (ADS)

The growth dynamics of an air finger injected in a visco-elastic gel (a PVA/borax aqueous solution) is studied in a linear Hele-Shaw cell. Besides the standard Saffman-Taylor instability, we observe—with increasing finger velocities—the existence of two new regimes: (a) a stick-slip regime for which the finger tip velocity oscillates between 2 different values, producing local pinching of the finger at regular intervals; (b) a "tadpole" regime where a fracture-type propagation is observed. A scaling argument is proposed to interpret the dependence of the stick-slip frequency with the measured rheological properties of the gel.

Puff, N.; Debrégeas, G.; di Meglio, J.-M.; Higgins, D.; Bonn, D.; Wagner, C.

2002-05-01

257

Slow Slip Earthquakes Controlled by Solitary Porosity Waves  

NASA Astrophysics Data System (ADS)

Episodic tremor and slip (ETS) found along the slipping interface of subduction zones and along plate boundaries provides compelling evidence for large regions of over-pressured fluids below seismogenic zones. ETS clusters below the brittle-ductile transition (BDT) between the 350-450 degree isotherms, with evidence that it occurs near the mantle wedge. Triggering of ETS by kPa shear stress perturbations from passing surface waves or tides leads to the general assumption that plate interface where this occurs is extremely weak. However, enhanced coupling where ETS exists implies that the interface supports high shear stresses while also accommodating over-pressured fluids. Here we demonstrate that plastic deformation and over-pressured fluids are coupled, and the result of this coupling explains all observations to date of ETS. Using a simple two-phase model of fluid flow within a non-Newtonian (e.g. power law) matrix, we show that slow slip events record the propagation of solitary waves mobilized by a large-scale reduction in the effective viscosity at the onset of slip. Buoyancy of the high pressure fluid-filled packet capitalizes on the reduced matrix viscosity, and a pressure pulse (porosity wave) propagates in a direction dictated by the prevailing pressure gradients. Prior to their mobilization, the trapped pockets generate tremor through identical crack-resonance mechanisms that control volcanic tremor, thus explaining how tremor and slow slip are manifestations of the same underlying mechanism. This model explains striations, and predicts that the seismic moment is proportional to the slip duration because the solitary wave velocity is constant and thus sweeps away accumulated seismic moment along its propagation path. This model also suggests a minimum magnitude for slow slip events, a constant stress drop if slip D is constant over the scale length W, and 1/f frequency spectra of far-field displacements, as observed. The implications of this model are far-reaching, establishing a basis for monitoring fluid migration and reservoir evolution prior to large earthquakes.

Miller, S. A.; Podladchikov, Y. Y.

2010-12-01

258

Coulombic wall slip of concentrated soft-particle suspensions  

NASA Astrophysics Data System (ADS)

The coefficients of friction of concentrated soft-particle suspensions (tomato paste and a microgel suspension) were measured as a function of the slip velocity for a number of substrates. The data are interpreted using a micro-elastohydrodynamic model that is consistent with significant bulk frictional dissipation and an increase in the number of particle-wall contacts with increasing normal stress. The origin of the Coulombic slip, which has not been observed previously for pastes, is ascribed to the sensitivity of the lubricating film thickness.

Adams, Michael; Liu, Wei; Zhang, Zhibing; Fryer, Peter

2013-06-01

259

Unsteady Couette Flow With Heat Transfer Considering Ion-Slip  

NASA Astrophysics Data System (ADS)

The unsteady Couette flow of an electrically conducting, viscous, incompressible fluid bounded by two parallel non-conducting porous plates is studied with heat transfer taking ion-slip into consideration. An external uniform magnetic field and a uniform suction and injection are applied perpendicular to the plates while the fluid motion is subjected to a constant pressure gradient. The two plates are kept at different but constant temperatures while the Joule and viscous dissipations are included in the energy equation. The effect of ion-slip an uniform suction and injection on both the velocity and temperature distributions is examined.

Attia, Hazem Ali

2005-11-01

260

Rupture of multiple catch-slip bonds: Two-state two-pathway catch-slip bonds.  

PubMed

We performed Monte Carlo simulation of the detachment of a polymorphonuclear (PMN) leukocyte immersed in a Newtonian fluid and adhered to a substrate by multiple catch-slip bonds. We found that at certain loading rates the interplay of multiple catch-slip bonds leads to a bimodal distribution of the bond rupture force. We also found that the low force peak in these bond rupture force distributions switches to a high force peak with a gradual increase in the loading rate. These trends in the bond rupture force distributions are characteristics of two-state systems. Consequently, though individual catch-slip bonds follow one-state two-pathway energy landscape, their interplay mimics a two-state two-pathway energy landscape. PMID:24272665

Gupta, V K

2013-11-01

261

Joint warfare system (JWARS)  

Microsoft Academic Search

The Joint Warfare System (JWARS) is a campaign-level model of military operations that is currently being developed under contract by the Office of the Secretary of Defense (OSD) for use by OSD, the Joint Staff, the Services, and the War fighting Commands. The behavior of military forces can be simulated from ports of embarkation through to their activities in combat.

A. Simlote

2003-01-01

262

Campylobacter Prosthetic Joint Infection  

PubMed Central

A 75-year-old man was diagnosed with probable Campylobacter jejuni prosthetic knee infection after a diarrheal illness. Joint aspirate and operative cultures were negative, but PCR of prosthesis sonicate fluid was positive, as was stool culture. Nineteen additional cases of Campylobacter prosthetic joint infection reported in the literature are reviewed. PMID:24523462

Vasoo, Shawn; Schwab, Jeramy J.; Cunningham, Scott A.; Robinson, Trisha J.; Cass, Joseph R.; Berbari, Elie F.; Walker, Randall C.; Osmon, Douglas R.

2014-01-01

263

Sustainable Chemistry, the Spinning Tube-in-Tube (STT(R)) Reactor and GREENSCOPE: Innovation and Industrial Partnerships  

EPA Science Inventory

The chemical industry faces environmental, social and health challenges that are common across all economic sectors. From worker exposure to toxic substances, to product design and use, to the cost and handling of waste disposal, the industry must overcome numerous complex hurdle...

264

Slip Partitioning Offshore Southeast Taiwan and Southward Propagation of the Longitudinal Valley Fault: Evidence from Preferred Nodal Plane Slip Vectors  

NASA Astrophysics Data System (ADS)

Slip vectors of preferred nodal planes derived using a Gaussian model for inverting focal mechanisms for strain provide constraints on probable fault geometries and fault block kinematics. We use preferred nodal plane slip vectors for shallow earthquakes in the Luzon forearc basin of southeast Taiwan to understand the relative orientations of block movement in an area responding to the initial collision between the Luzon arc and the Eurasian passive margin. South of the forearc basin, where the accretionary prism and Luzon arc are bathymetrically separated, slip vectors suggest that relative plate motion is spatially partitioned into two domains with backthrusting within the accretionary prism and sinistral shearing centered within the volcanic arc. North of this region is the Taitung Trough, a bathymetric low just west of the Luzon arc. Slip vectors within the southern part of the trough have orientations both ~E - W and ~N - S, suggesting the basin has mostly closed and that the accretionary prism and Luzon arc have been juxtaposed. Likewise, the partitioning of relative plate motion appears to be accommodated by a single structure in map view. Going north from the Taitung Trough, slip vectors rotate toward parallelism with the Philippine convergence vector, which we interpret as the transition from partitioned deformation to full collisional deformation. Slip vectors within the southern region of the Longitudinal Valley, near the Pinanshan Conglomerate, have orientations that are parallel to those of the blocks of the area bounded by two branches of the Longitudinal Valley fault. The southern part of the Longitudinal Valley fault's eastern branch continues southeast offshore, within the same region as the NW-trending Taitung Trough. This analysis suggests the eastern branch of the Longitudinal Valley fault propagates southward offshore, becoming the Taitung Trough.

O'hara, D.; Lewis, J. C.; Rau, R.

2011-12-01

265

Resonant slow fault slip in subduction zones forced by climatic load stress.  

PubMed

Global Positioning System (GPS) measurements at subduction plate boundaries often record fault movements similar to earthquakes but much slower, occurring over timescales of approximately 1 week to approximately 1 year. These 'slow slip events' have been observed in Japan, Cascadia, Mexico, Alaska and New Zealand. The phenomenon is poorly understood, but several observations hint at the processes underlying slow slip. Although slip itself is silent, seismic instruments often record coincident low-amplitude tremor in a narrow (1-5 cycles per second) frequency range. Also, modelling of GPS data and estimates of tremor location indicate that slip focuses near the transition from unstable ('stick-slip') to stable friction at the deep limit of the earthquake-producing seismogenic zone. Perhaps most intriguingly, slow slip is periodic at several locations, with recurrence varying from 6 to 18 months depending on which subduction zone (or even segment) is examined. Here I show that such periodic slow fault slip may be a resonant response to climate-driven stress perturbations. Fault slip resonance helps to explain why slip events are periodic, why periods differ from place to place, and why slip focuses near the base of the seismogenic zone. Resonant slip should initiate within the rupture zone of future great earthquakes, suggesting that slow slip may illuminate fault properties that control earthquake slip. PMID:16915286

Lowry, Anthony R

2006-08-17

266

The influence of slip velocity and temperature on permeability during and after high-velocity fault slip  

NASA Astrophysics Data System (ADS)

Fluid transport properties in fault zones play an important role in dynamic processes during large earthquakes. If the permeability in a fault zone is low, high pore-fluid pressures caused by thermal pressurization (Sibson, 1973) or shear-induced compaction (Blanpied et al., 1992) can lead to an apparent reduction of fault strength. Changes in porosity and permeability of fault rocks within a fault zone during earthquakes and the subsequent progressive recovery of these properties may have a large influence on earthquake recurrence (Sleep and Blanpied, 1992). A rotary shear apparatus was used to investigate changes of fluid transport properties in a fault zone by real-time measurement of gas flow rates during and after shearing of hollow sandstone and granite cylinders at various slip rates. Our apparatus measures permeability parallel to the slip plane in both the slip zone and wall rocks. In all cases, permeability decreased rapidly with an increase of friction, but recovered soon after slip, reaching a steady state within several tens of minutes. The rate of reduction of permeability increased with increasing slip velocity. Permeability did not recover to pre-slip levels after low-velocity tests but recovered to exceed them after high-velocity tests. Frictional heating of gases at the slip surface increased gas viscosity, which increased gas flow rate to produce an apparent permeability increase. The irreversible permeability changes of the low-velocity tests were caused by gouge formation due to wearing and smoothing of the slip surface. The increase of permeability after high-velocity tests was caused by mesoscale fracturing in response to rapid temperature rise. Changes of pore fluid viscosity contributed more to changes of flow rate than did permeability changes caused by shear deformation, although test results from different rocks and pore fluids might be different. References Blanpied, M.L., Lockner, D.A., Byerlee, J.D., 1992. An earthquake mechanism based on rapid sealing of faults. Nature 358, 574-576 Sibson, R.H., 1973. Interactions between temperature and pore fluid pressure during earthquake faulting: A mechanism for partial or total stress relief. Nature 243, 66-68. Sleep, N.H., Blanpied, M.L., 1992. Creep, compaction and the weak rheology of major faults. Nature 359, 687-692.

Tanikawa, W.; Mukoyoshi, H.; Tadai, O.; Hirose, T.; Lin, W.

2011-12-01

267

Slip modelling and aided inertial navigation of an LHD  

Microsoft Academic Search

This paper describes the theoretical development and experimental evaluation of a guidance system for an autonomous load, haul and dump truck (LHD) for use in underground mining. The particular contributions of this paper are in designing the navigation system to be able to cope with vehicle slip in rough uneven terrain using information from an inertial navigation system (INS) and

S. Scheding; G. Dissanayake; E. Nebot; H. Durrant-Whyte

1997-01-01

268

Thermal effect on piezoelectric stick-slip actuator systems.  

PubMed

The piezoelectric stick-slip (PZT-SS) actuator is known to achieve motion with a theoretically unlimited range yet high resolution (several nanometers). In this type of actuator, friction plays an active role in producing a meaningful stick-slip motion. However, friction is a source of heat which may cause significant temperature rise, affecting the dynamic performance of the actuator. Our study aimed to measure temperature rise in the stick-slip motion and to understand whether such a rise could significantly affect the displacement of the stick-slip motion. In this study, a temperature measurement system was developed using the off-the-shelf components, with which the temperature rise up to 0.436 degrees C was successfully measured on a proprietary PZT-SS actuator. The experiment further shows that the temperature rise affects the displacement of the actuator when operating voltage is at the low end (approximately 6 V). Therefore, one of the design recommendations for such an actuator system is that the operating voltage should be at the high end (approximately 30 V). The study also measured the temperature rise (approximately 0.263 degrees C after the system worked for 6300 s) at the friction interface due to the piezoelectric element which is a part of the whole PZT-SS actuator. This means that temperature rise is due to both the friction at two interacting surface and the operation of the piezoelectric element. PMID:18447566

Li, J W; Yang, G S; Zhang, W J; Tu, S D; Chen, X B

2008-04-01

269

Experimental Investigations Of Failure Mechanisms Associated With Slow Slip Events  

NASA Astrophysics Data System (ADS)

Slow slip events such as very low frequency earthquakes (VLFEs) are detected in the Nankai accretionary prism [Ito and Obara, 2006]. It is proposed that high pore fluid pressure weakens the out-of-sequence-thrusts and mega-splay faults by reducing effective normal stress on the fault plane and consequently generates slip instability producing low stress drop VLFEs. However, the frictional behaviors and failure mechanisms associated with reduction of effective normal stress are not well understood. In this study, we conducted frictional experiments on porous sedimentary rocks with a saw-cut. Sediments with different clay content from NantroSEIZE drilling project ODP Legs 315, 316, and 322 are used as fault gouge. A new triaxial loading configuration was designed to investigate the effect of high pore pressure on frictional instability and failure modes. During the deformation experiments, samples were subjected to constant axial stress and decreasing radial stresses. Distinguishing from the conventional loading configuration in which mean stress increases during deformation, with the alternative loading path, mean stress decreases during deformation. Under fully drained conditions where pore pressure remains constant, the effective stress decreases in these experiments, analoguous to increasing pore pressure. Our preliminary results indicate that: 1) frictional strength is comparable to that observed under conventional loading; 2) the rate of fracture energy release is considerably slower, which bears similar characteristics with observed slow slip events. Microstructural analyses on the deformed samples provide experimental constraints on deformation mechanisms associated with slow slip events.

Zhu, W.; Tamarkin, T.

2010-12-01

270

Multi-Modal Monitoring of Slip Along Frictional Discontinuities  

NASA Astrophysics Data System (ADS)

Seismic wave transmission and digital image correlation (DIC) are employed to study slip processes along frictional discontinuities. A series of biaxial compression experiments are performed on gypsum specimens with non-homogeneous contact surfaces. The specimens are composed of two blocks with perfectly mated contact surfaces with a smooth surface with low frictional strength on the upper half and a rough surface with high frictional strength on the lower half. Compressional, P, and shear, S, wave pulses were transmitted through the discontinuity while digital images of the specimen surface were acquired during the test. A distinct peak in the amplitude of transmitted wave occurs prior to the peak shear strength and is considered a "precursor" to the failure. Precursors indicate that slip initiates from the smooth surface and extends to the rough surface as the shear load is increased. From the DIC data, slip is identified as a jump in the displacement field along the fracture that initiates from the smooth surface and propagates to the rough surface. Precursors are associated with an increase in the rate of slip across the discontinuity and are a measure of the reduction in the fracture shear stiffness.

Hedayat, Ahmadreza; Pyrak-Nolte, Laura J.; Bobet, Antonio

2014-09-01

271

Two-plane balance and slip-ring design  

NASA Technical Reports Server (NTRS)

A 3.25 cm (1.28 in.) two plane balance and eight channel slip ring assembly has been designed to measure and transmit the thrust (667-N;150-lb) and torque (135-N-m;100-lb-ft) components produced by wind tunnel model turboprops and drive motors operating at 300 Hz.

Luna, P. M.

1985-01-01

272

Transmission of a Screw Dislocation Across a Coherent, Slipping Interface  

E-print Network

1 Transmission of a Screw Dislocation Across a Coherent, Slipping Interface Yao Shen(a) and Peter M of interfacial sliding during dislocation transmission. A straight screw dislocation parallel to a bimaterial. Interfacial sliding is predicted to increase the critical applied shear crit of interfaces for transmission

Anderson, Peter M.

273

Slip-based tire-road friction estimation  

Microsoft Academic Search

An approach to estimate the tire-road friction during normal drive using only the wheel slip, that is, the relative difference in wheel velocities, is presented. The driver can be informed about the maximum friction force and be alarmed for sudden changes. Friction-related parameters are estimated using only signals from standard sensors in a modern car. An adaptive estimator is presented

Fredrik Gustafsson

1997-01-01

274

Earthquake-Like Slip Events on a Laboratory Fault  

Microsoft Academic Search

We generated dynamic slip events with prescribed total energy on an experimental fault. Sliding occurred between granite rings, in a rotary shear apparatus driven by a 100 hp motor and a massive flywheel (225 kg) at normal stress up to 7 MPa (Lockner and Reches, this meeting). In the experiments, the motor first brought the flywheel to a pre-selected angular

J. C. Chang; Z. Reches; D. A. Lockner; M. W. Totten Jr.

2009-01-01

275

A slip-line field model of abrasive wear  

Microsoft Academic Search

Slip-line fields are used to describe the three main interactions between abrasive grit and metal: ploughing, wedge formation and cutting. Combining these with ratchetting, or low-cycle fatigue models of mild wear, allows wear coefficients to be predicted from the mechanical properties of the metal and the profile of the abrasive. The predictions are verified by experiment, and are in accord

A. A. Torrance; T. R. Buckley

1996-01-01

276

Slip-Based Estimation Of Tire---Road Friction  

Microsoft Academic Search

An approach to estimate the tire--road friction duringnormal drive using only the wheel slip, that is, the relativedifference in wheel velocities, is presented. The drivercan be informed about the maximal friction force and bealarmed for sudden changes. Friction related parametersare estimated using only signals from standard sensorsin a modern car, and the physical relation between theseparameters and the maximal friction

F. Gustafsson

1993-01-01

277

An Analysis of Strain Accumulation on a Strike Slip Fault  

Microsoft Academic Search

An analysis of strain accumulation on a strike slip fault is given. The fault between two lithospheric plates is assumed to be locked tb a finite depth; owing to plastic flow the fault is free to slide at greaier depths. The base of each plate is also a free boundary. The periodic stress accumulation andtress release associated with the elastic

D. L. Turcotte; D. A. Spence

1974-01-01

278

Slipping Detection with Integrated Piezoelectric Vibration Tactile Sensors  

Microsoft Academic Search

This paper presents the detection of slipping with integrated piezoelectric vibration tactile sensors. A tactile sensor is important for robotics to find a mechanical pressure and contact condition between grippers and objects. We have proposed the integrated piezoelectric vibration-type tactile sensors to realize a high sensitivity and a wide measurement range. Previous sensors were only applied to measure the pressure

S. Kosaka; M. Nakajima; T. Fukuda; H. Matsuura

2008-01-01

279

Reply: Central American forearc slip revisited Charles DeMets  

E-print Network

Reply: Central American forearc slip revisited Charles DeMets Department of Geology and Geophysics; published XX Month 2002. [1] I thank Guzman-Speziale and Gomez (GSG02) for their comments on DeMets (2001 in this region [White, 1991; DeMets, 2001]. Below, I address their reservations. INDEX TERMS: 8107 Tectonophysics

DeMets, Chuck

280

Designer friction laws for bimodal slow slip propagation speeds  

Microsoft Academic Search

A striking observation from both Cascadia and Japan is that the tremor associated with slow slip often migrates along strike at speeds close to 10 km\\/d but updip and downdip at speeds approaching 100 km\\/h. In this paper I adopt the view that the friction law appropriate for these regions is unknown, and I ask what constraints the observed behavior

Allan M. Rubin

2011-01-01

281

Boundary slip in Newtonian liquids: a review of experimental studies  

Microsoft Academic Search

For several centuries fluid dynamics studies have relied upon the assumption that when a liquid flows over a solid surface, the liquid molecules adjacent to the solid are stationary relative to the solid. This no-slip boundary condition (BC) has been applied successfully to model many macroscopic experiments, but has no microscopic justification. In recent years there has been an increased

Chiara Neto; Drew R. Evans; Elmar Bonaccurso; Hans-Jürgen Butt; Vincent S. J. Craig

2005-01-01

282

When Malaria Slips a Vaccine's Net Caitlin Sedwick*  

E-print Network

Synopsis When Malaria Slips a Vaccine's Net Caitlin Sedwick* Freelance Science Writer, San Diego is currently being made to develop vaccines against the parasite. But here, too, the organism's adaptability works against us. Many malarial vaccines work by exposing people to a single purified parasite protein

Read, Andrew

283

Hip joint replacement - series (image)  

MedlinePLUS

... pain that limits what you can do. Hip joint replacement is usually done in people age 60 and ... Hip joint replacement is surgery to replace all or part of the hip joint with a man-made or artificial ...

284

Strike-slip Faulting On Ganymede, Now And Then  

NASA Astrophysics Data System (ADS)

Strike-slip tectonism is important to the structural development of Ganymede’s surface, and in the transition from dark to grooved terrain. Three distinct signatures of strike-slip faulting are recognized [1]: (1) en echelon structures, (2) strike-slip duplexes, and (3) laterally offset pre-existing features. As strike-slip faulting progressed, en echelon fractures (in both dark and grooved terrains) merged to define en echelon swaths, which can become distinct tectonic domains. Three morphological categories of strike-slip “duplexes” (spindle-shaped lensoid regions bounded by strike-slip faults) occur, suggesting an evolutionary sequence from discontinuous fractures in dark terrain, to lensoid bounding structures, to lensoid regions with subparallel internal structure in grooved terrain. Ganymede’s 24 measured duplexes have an average length/width ratio of 2.4, on the low end of the terrestrial range [2]. Lateral offsets of pre-existing features betray the existence of some major strike-slip faults: Dardanus Sulcus (13°W, 18°S) is displaced 45 km by a prominent NE-SW trending fault. We model Coulomb shear failure on Ganymede, considering nonsynchronous rotation (NSR), and diurnal stresses both for present (0.0013) and possible past high ( 0.05) eccentricity [3]. We adopt NSR period 0.14 Ma; Love numbers h2 = 1.52 and l2 = 0.38; Young’s modulus 9.3 GPa; Poisson’s ratio 0.33; and fault depth 2 km. NSR shear stress resolved along the Dardanus fault is 0.3 MPa, sufficient to induce failure to 1.4 km for friction coefficient 0.3. For past high eccentricity, diurnal stress would have modulated NSR stress by 100 kPa through Ganymede’s tidal cycle. This could have induced shear heating [4] and tidal walking [5], as modeled for Europa. References: [1] DeRemer and Pappalardo (2003), LPSC, 34, #2033; [2] Aydin and Nur (1982), Tectonics, 1, 91; [3] Showman and Malhotra (1997), Icarus, 127, 93; [4] Nimmo and Gaidos (2002), JGR, 107, 10.1029/2000JE001476; [5] Rhoden et al. (2012), Icarus, 218, 297.

Pappalardo, Robert T.; Smith-Konter, B. R.; Cameron, M. E.; DeRemer-Keeney, L. C.; Nimmo, F.

2012-10-01

285

Do All Large Strike-slip Earthquakes Have Supershear Ruptures?  

NASA Astrophysics Data System (ADS)

Studying the rupture speeds of earthquakes is of broad interesting for earthquake research because it has a large effect on the strong near-field shaking that causes damage during earthquakes. Also rupture speed is a key observation for understanding the controlling stresses and friction during an earthquake, yet the speed and its variations are usually difficult to determine. Using only far-field seismic waveforms, which is the only data available for many large earthquakes, there are problems for estimating the rupture speed with standard waveform inversions, due to trade-off between the rupture speed and the slip location. Here we applied a back projection method to estimate the rupture speeds of Mw ? 7.5 strike-slip earthquakes since 2001 which could be analyzed using Hi-net in Japan. We found that all events had very fast average rupture speeds of 3.0-6.0 km/s, which are near or greater than the local shear wave velocity (supershear). These values are faster than for thrust and normal faulting earthquakes that generally rupture with speeds of 1.0-3.0 km/s. Considering the depth-dependent shear-wave velocity, the average propagation speeds for all of the strike-slip events are closer to or greater than the shear wave velocity (Figure 1). For large strike-slip events, transition from subshear to supershear usually occurs within distances of 15 to 30 km from the initiation, which is probably the reason for the scarcity of observed supershear earthquakes for smaller magnitudes. Earthquakes with supershear ruptures can cause more damage than events with subshear ruptures because of the concentration of energy in the forward direction of the rupture. Numerical modeling shows strong focusing and other effects of energy at the rupture front which can intensify the ground motions. A recent example is the April 13, 2010 Qinghai, China earthquake (Mw 6.9), where a moderate-size event caused extensive damage in the Yushu region at the southeastern end of the fault. Careful evaluation of long and straight strike-slip faults should be emphasized for predicting strong ground motions due to supershear rupture. a: Average rupture speeds for Mw ? 7.5 strike-slip earthquakes. For comparison, dip-slip earthquakes are also shown. The blue dashed line presents the S wave velocity model of PREM for comparison. b: Rupture velocities are shown as ratio to the local S wave velocity, as a function of depth.

Wang, D.; Mori, J. J.; Koketsu, K.

2013-12-01

286

Steady-state friction during earthquake slip: Fact or myth?  

NASA Astrophysics Data System (ADS)

The rupture front of an earthquake propagates along a fault while activating countless patches. Each patch undergoes intense deformation variations from rest before the front developing to acceleration, weakening, deceleration and healing. While it is unlikely that steady-state stage would materialize in such history during rise-time, the modeling of earthquake rupture is almost exclusively based on friction measurements conducted under steady-state condition. An alternative approach is presented here. Experimentally, the friction strength of a fault is determined by its relations to the slip-distance and slip-velocity, and these relations are implicitly assumed to be rock properties. Recent observations however, show that these relations strongly depend on the slip-velocity history. Consider three styles of velocity loading: Impact (abrupt increase followed by gradual deceleration), constant (steady velocity), and ramp (gradual increase followed by abrupt deceleration). Chang et al. (2012) found that running the same sample (Sierra White granite) under different velocity loading yielded different relations: Impact loading had much shorter critical weakening distance (0.03 m for impact and 1-3 m for constant), and drastic dynamic weakening under high velocity (V > 0.1 m/s), whereas dynamic strengthening was observed under V > 0.05 m/s for constant velocity. Similar behavior was recently observed for an experimental fault made of syenite under impact and ramp loading. Further, under impact velocity, the period of velocity increase (acceleration) overlaps the period of fault weakening. This correlation is not unique and similar weakening-acceleration associations were reported in stick-slip experiments (Ohnaka & Yamashita, 1989), rotary shear (Goldsby & Tullis, 2011), and Kolsky impact shear experiments (Yuan & Prakash, 2008). These studies greatly differ from each other in slip distance, normal stress, acceleration, and slip-velocities with the outstanding commonality of impact velocity loading. Analyses of seismic data (e.g., Tinti et al., 2005) and numerical simulation of earthquake rupture (e.g., Day et al., 2005), indicate that the early slip of a fault patch is characterized by intense acceleration. Based on these experimental and modeling results we conclude that dynamic frictional strength, which is determined in steady-state experiments, is not necessarily relevant to fault strength during earthquakes. More relevant experiments should be conducted under impact loading that better fits high velocity rupture propagation.

Reches, Zeev; Chang, Jefferson

2013-04-01

287

Tectonic release from the Soviet joint verification experiment  

SciTech Connect

The regional broadband seismic recordings of the Soviet Joint Verification Experiment underground nuclear explosion show evidence of tectonic release in the form of Love waves at long periods and high-frequency S{sub m}S phases on the transverse components. The authors present the results of some simple forward modeling of this data in order to quantify both the moment and mechanism of the tectonic release. Using 10-20 second Love wave amplitude and phase data, they estimate the tectonic release moments to be 3.5 {times} 10{sup 15} N-m for a north striking right-lateral strike-slip fault, and 7.0 {times} 10{sup 15} N-m for a northwest striking reverse fault. Using the results of these end member tectonic models, the Rayleigh waves can be satisfied with explosion moments of 1.7 {times} 10{sup 16} N-m (F=0.31) and 2.4 {times} 10{sup 16} N-m (F=0.44), respectively. To resolve the ambiguity in tectonic mechanism the authors used the reflectivity method to generate synthetics and compare the relative amplitudes of the SH and SV parts of the S{sub m}S phase. While the results favor the strike-slip mechanism of tectonic release, application of source inversion techniques to this data and other regional data will be needed to evaluate more realistic tectonic release models involving, for example, oblique fault slip and dip.

Walter, W.R. (Univ. of Nevada, Reno (USA)); Patton, H.J. (Lawrence Livermore National Laboratory, CA (USA))

1990-09-01

288

Airborne Antenna System for Minimum-Cycle-Slip GPS Reception  

NASA Technical Reports Server (NTRS)

A system that includes a Global Positioning System (GPS) antenna and associated apparatus for keeping the antenna aimed upward has been developed for use aboard a remote-sensing-survey airplane. The purpose served by the system is to enable minimum- cycle-slip reception of GPS signals used in precise computation of the trajectory of the airplane, without having to restrict the airplane to maneuvers that increase the flight time needed to perform a survey. Cycle slip signifies loss of continuous track of the phase of a signal. Minimum-cycle-slip reception is desirable because maintaining constant track of the phase of the carrier signal from each available GPS satellite is necessary for surveying to centimeter or subcentimeter precision. Even a loss of signal for as short a time as a nanosecond can cause cycle slip. Cycle slips degrade the quality and precision of survey data acquired during a flight. The two principal causes of cycle slip are weakness of signals and multipath propagation. Heretofore, it has been standard practice to mount a GPS antenna rigidly on top of an airplane, and the radiation pattern of the antenna is typically hemispherical, so that all GPS satellites above the horizon are viewed by the antenna during level flight. When the airplane must be banked for a turn or other maneuver, the reception hemisphere becomes correspondingly tilted; hence, the antenna no longer views satellites that may still be above the Earth horizon but are now below the equatorial plane of the tilted reception hemisphere. Moreover, part of the reception hemisphere (typically, on the inside of a turn) becomes pointed toward ground, with a consequent increase in received noise and, therefore, degradation of GPS measurements. To minimize the likelihood of loss of signal and cycle slip, bank angles of remote-sensing survey airplanes have generally been limited to 10 or less, resulting in skidding or slipping uncoordinated turns. An airplane must be banked in order to make a coordinated turn. For small-radius, short-time coordinated turns, it is necessary to employ banks as steep as 45 , and turns involving such banks are times and for confining airplanes as closely as possible to areas to be surveyed. The idea underlying the design is that if the antenna can be kept properly aimed, then the incidence of cycle slips caused by loss or weakness of signals can be minimized. The system includes an articulating GPS antenna and associated electronic circuitry mounted under a radome atop an airplane. The electronic circuitry includes a microprocessor-based interface-circuit-and-data-translation module. The system receives data on the current attitude of the airplane from the inertial navigation system of the airplane. The microprocessor decodes the attitude data and uses them to compute commands for the GPS-antenna-articulating mechanism to tilt the antenna, relative to the airplane, in opposition to the roll or bank of the airplane to keep the antenna pointed toward the zenith. The system was tested aboard the hurricane- hunting airplane of the National Oceanic and Atmospheric Administration (NOAA) [see figure] during an 11-hour flight to observe the landfall of Hurricane Bret in late summer of 1999. No bank-angle restrictions were imposed during the flight. Post-flight analysis of the GPS trajectory data revealed that no cycle slip had occurred.considered normal maneuvers. These steep banks are highly desirable for minimizing flight

Wright, C. Wayne

2009-01-01

289

Compositional, mechanical and hydrologic controls on fault slip behavior  

NASA Astrophysics Data System (ADS)

In order to examine the roles of a variety of factors that are likely important in regulating the occurrence or lack of seismic slip, I evaluate the results of numerous laboratory studies of fault behavior, focusing on the effects of fault mineralogy, mechanical effects, and interactions between fluids and faulting processes. More specifically, these experiments are designed to investigate the underlying mechanisms controlling the transition from aseismic slip at shallow levels in the crust to seismic slip at depth, known as the updip limit of the seismogenic zone. Results of laboratory experiments indicate that mineralogy of fault gouge is a major control on fault behavior. The clay mineral montmorillonite (smectite) has been noted for its potential effect on seismogenesis in subduction zones (as well as all faults in general) due to its ability to take up water in its crystal structure. Dehydration of montmorillonite tends to increase its frictional strength as well as increase its propensity for seismic slip, as documented by a decrease in the frictional velocity dependence parameter a-b. However, the observed decrease in a-b is assisted by both increasing relative quartz percentage and increasing normal stress, implying that the onset of seismic behavior with increasing depth should not be attributed solely to smectite dehydration. Furthermore, clay-rich gouges in general, including those consisting of montmorillonite, illite, and chlorite, are both frictionally weak (mu < 0.35) and velocity-strengthening (frictionally stable, a-b > 0) at fluid-saturated conditions and effective normal stresses up to ˜60 MPa. Sheared gouges may also exhibit low fault-perpendicular permeability (k < 1x10-18), making them candidates to host high pore pressure. This indicates that faults containing granular, clay-rich gouges are unlikely to show seismic behavior, due their velocity-strengthening nature and stabilizing hydro-mechanical effects resulting from low permeability. In comparing the frictional behavior of granular gouge and lithified fault rock as an analogue for cataclastic fault rocks at seismogenic depths, the lithification of fault rock is found to have a significant strengthening effect, however in phyllosilicate-rich rocks pre-existing foliation provides a weakening mechanism that offsets the strengthening due to lithification. This weakening depends on the intensity of foliation such that strongly foliated rocks, such as books of mica sheets, are significantly weaker than granular mica gouges. Very thick fault zones can exhibit a reduction in measured apparent friction, the magnitude of which may be related to the orientation of through-going R1 shears and internal structural complexity. Consistent velocity-strengthening behavior is observed for both lithified and granular phyllosilicate-rich samples despite the observation of slip localization features in microstructural analysis, suggesting that as an isolated parameter advanced lithification state of fault rock is also inadequate for allowing seismic slip nucleation. Collectively, the results of the experiments in this study have several important implications for fault slip behavior. Granular, unconsolidated phyllosilicate-rich gouges, such as those that are common at shallow depths in both subduction zones and strike-slip faults, will tend to be aseismic, a condition that may be related to their overall weakness. The transition from aseismic to seismic slip at the updip limit of the seismogenic zone should be driven by changes in pressure and temperature, due to the overall ambient conditions as well as inducing changes in the character of the fault material itself. These may include compositional changes and mechanical effects of the lithification process, such as consolidation and cementation. However, when tested as isolated variables, the dehydration of smectite, conversion of smectite to illite, and lithification of fault gouge were found to be insufficient in allowing unstable slip behavior. It is possible that these processes may still play a rol

Ikari, Matt J.

290

SH Wave Scattering from Fractures using Boundary Element Method with Linear Slip Boundary Condition  

E-print Network

A boundary element method (BEM) combined with a linear slip boundary condition is proposed to calculate SH wave scattering from fractures. The linear slip boundary condition was proposed by Schoenberg (1980) to model elastic ...

Chen, Tianrun

2011-01-01

291

Pressure vessel flex joint  

NASA Technical Reports Server (NTRS)

An airtight, flexible joint is disclosed for the interfacing of two pressure vessels such as between the Space Station docking tunnel and the Space Shuttle Orbiter bulkhead adapter. The joint provides for flexibility while still retaining a structural link between the two vessels required due to the loading created by the internal/external pressure differential. The joint design provides for limiting the axial load carried across the joint to a specific value, a function returned in the Orbiter/Station tunnel interface. The flex joint comprises a floating structural segment which is permanently attached to one of the pressure vessels through the use of an inflatable seal. The geometric configuration of the joint causes the tension between the vessels created by the internal gas pressure to compress the inflatable seal. The inflation pressure of the seal is kept at a value above the internal/external pressure differential of the vessels in order to maintain a controlled distance between the floating segment and pressure vessel. The inflatable seal consists of either a hollow torus-shaped flexible bladder or two rolling convoluted diaphragm seals which may be reinforced by a system of straps or fabric anchored to the hard structures. The joint acts as a flexible link to allow both angular motion and lateral displacement while it still contains the internal pressure and holds the axial tension between the vessels.

Kahn, Jon B. (inventor)

1992-01-01

292

Subcapital osteotomy of the femoral neck for patients with healed slipped capital femoral epiphysis.  

PubMed

We report the clinical and radiological outcome of subcapital osteotomy of the femoral neck in the management of symptomatic femoroacetabular impingement (FAI) resulting from a healed slipped capital femoral epiphysis (SCFE). We believe this is only the second such study in the literature. We studied eight patients (eight hips) with symptomatic FAI after a moderate to severe healed SCFE. There were six male and two female patients, with a mean age of 17.8 years (13 to 29). All patients underwent a subcapital intracapsular osteotomy of the femoral neck after surgical hip dislocation and creation of an extended retinacular soft-tissue flap. The mean follow-up was 41 months (20 to 84). Clinical assessment included measurement of range of movement, Harris Hip Score (HHS) and Western Ontario and McMaster Universities Osteoarthritis score (WOMAC). Radiological assessment included pre- and post-operative calculation of the anterior slip angle (ASA) and lateral slip angle (LSA), the anterior offset angle (AOA) and centre head-trochanteric distance (CTD). The mean HHS at final follow-up was 92.5 (85 to 100), and the mean WOMAC scores for pain, stiffness and function were 1.3 (0 to 4), 1.4 (0 to 6) and 3.6 (0 to 19) respectively. There was a statistically significant improvement in all the radiological measurements post-operatively. The mean ASA improved from 36.6° (29° to 44°) to 10.3° (5° to 17°) (p < 0.01). The mean LSA improved from 36.6° (31° to 43°) to 15.4° (8° to 21°) (p < 0.01). The mean AOA decreased from 64.4° (50° to 78°) 32.0° (25° to 39°) post-operatively (p < 0.01). The mean CTD improved from -8.2 mm (-13.8 to +3.1) to +2.8 mm (-7.6 to +11.0) (p < 0.01). Two patients underwent further surgery for nonunion. No patient suffered avascular necrosis of the femoral head. Subcapital osteotomy for patients with a healed SCFE is more challenging than subcapital re-orientation in those with an acute or sub-acute SCFE and an open physis. An effective correction of the deformity, however, can be achieved with relief of symptoms related to impingement. Cite this article: Bone Joint J 2014;96-B:1441-8. PMID:25371454

Bali, K; Railton, P; Kiefer, G N; Powell, J N

2014-11-01

293

The 1994 Java tsunami earthquake: Slip over a subducting seamount  

NASA Astrophysics Data System (ADS)

On June 2, 1994, a large subduction thrust earthquake (Ms 7.2) produced a devastating tsunami on the island of Java. This earthquake had a number of unusual characteristics. It was the first recorded large thrust earthquake on the Java subduction zone. All of the aftershock mechanisms exhibit normal faulting; no mechanisms are similar to the main shock. Also, the large tsunami and the relatively low energy radiated by the main shock have led to suggestions that this earthquake might have involved slow, shallow rupture near the trench, similar to the 1992 Nicaragua earthquake. We first relocate the main shock and the aftershocks. We then invert long-period surface waves and broadband body waves to determine the depth and spatial distribution of the main shock slip. A dip of 12°, hypocenter depth of 16 km and moment of 3.5×l020 N m (Mw 7.6) give the best fit to the combined seismic data and are consistent with the plate interface geometry. The source spectrum obtained from both body and surface waves has a single corner frequency (between 10 and 20 mHz) implying a stress drop of ˜0.3 MPa. The main energy release was preceded by a small subevent lasting ˜12 s. The main slip occurred at ˜20 km depth, downdip and to the NW of the hypocenter. This area of slip is collocated with a prominent high in the bathymetry that has been identified as a subducting seamount. We interpret the Java earthquake as slip over this subducting seamount, which is a locked patch in an otherwise decoupled subduction zone. We find no evidence for slow, shallow rupture. No thrust aftershocks are expected if the entire locked zone slipped during the main shock, but extension of the subducting plate behind the seamount would promote normal faulting as observed. It seems probable that such a source model could also explain the size and timing of the observed tsunami.

Abercrombie, Rachel E.; Antolik, Michael; Felzer, Karen; EkströM, GöRan

2001-04-01

294

Distribution of Slip at the Northern Sumatran Fault System  

NASA Technical Reports Server (NTRS)

We model spatial variations in horizontal displacements of 117 geodetic sites measured during annual surveys in 1989-1996 with the Global Positioning System (GPS) as elastic strain across a locked strike-slip fault to infer the contemporary slip rate, locking depth, and location of the Sumatran fault (SF) in northern Sumatra (1 S-3 N). GPS-derived slip rate estimates increase slightly northward from 23 plus or minus 3 mm/yr at 0.8 deg S to 26 plus or minus 2mm/yr at 2.7 N. They agree with geologic estimates north of the Equator, but at 0.5 S they are about 10 mm/yr higher. Strain appears to be distributed asymmetrically about the fault. South of 2 N, about 5 mm/yr of shear is required within the offshore forearc, west of the fault, to achieve a closer agreement of fault locations inferred from GPS velocities with geologically identified traces of the SF. Locking depth estimates are on the order of 10-20 km. The western branch of the major fault bifurcation near 1 N slips at a rate five times higher than the eastern branch. The two main strands of the fault at the northwestern tip of Sumatra (5.5 N) appear to be nearly free of horizontal strain; significant slip must occur away from the two strands, probably further east at two other geologically active branches. The Banda Aceh embayment is extruded to the northwest at a rate of 5 plus or minus 2 mm/yr. Within the estimated velocity uncertainties of several mm/yr, fault-normal deformation along the SF is insignificant. Almost strain free, the northern part of the back-arc basin is part of a rigid Sunda shelf, while the northern forearc is subjected to 8 plus or minus 5 x 10 (exp -8)/yr of extension nearly parallel to the arc.

Genrich, J. F.; Bock, Y.; McCaffrey, R.; Prawirodirdjo, L.; Stevens, C. W.; Puntodewo, S. S. O.; Subarya, C.; Wdowinski, S.

2000-01-01

295

Measurement of Quantum Phase-Slips in Josephson Junction Chains  

NASA Astrophysics Data System (ADS)

Quantum phase-slip dynamics in Josephson junction chains could provide the basis for the realization of a new type of topologically protected qubit [1] or for the implementation of a new current standard [2]. I will present measurements of the effect of quantum phase-slips on the ground state of a Josephson junction chain. We can tune in situ the strength of the phase-slips. These phase-slips are the result of fluctuations induced by the finite charging energy of each junction in the chain. Our measurements demonstrate that a Josephson junction chain under phase bias constraint behaves in a collective way [3]. I will also show evidence of coherent phase-slip interference, the so called Aharonov-Casher effect. This phenomenon is the dual of the well known Aharonov-Bohm interference.[4pt] In collaboration with I.M. Pop, Institut Neel, C.N.R.S. and Universite Joseph Fourier, BP 166, 38042 Grenoble, France; I. Protopopov, L. D. Landau Institute for Theoretical Physics, Kosygin str. 2, Moscow 119334, Russia and Institut fuer Nanotechnologie, Karlsruher Institut fuer Technologie, 76021 Karlsruhe, Germany; and F. Lecocq, Z. Peng, B. Pannetier, O. Buisson, Institut Neel, C.N.R.S. and Universite Joseph Fourier. [4pt] [1] I. M. Pop, O. Buisson, K. Hasselbach, I. Protopopov, W. Guichard and B. Pannetier, Phys. Rev. B, 78, 104504(2008) [0pt] [2] W. Guichard and F. Hekking, Phys. Rev. B 81, 064508 (2010) [0pt] [3] I. M. Pop, I. Protopopov, F. Lecocq, Z. Peng, B. Pannetier, O. Buisson and W. Guichard, Nature Physics, 6, 589 (2010).

Guichard, Wiebke

2011-03-01

296

Triggered surface slips in the Salton Trough associated with the 1999 Hector Mine, California, earthquake  

USGS Publications Warehouse

Surface fracturing occurred along the southern San Andreas, Superstition Hills, and Imperial faults in association with the 16 October 1999 (Mw 7.1) Hector Mine earthquake, making this at least the eighth time in the past 31 years that a regional earthquake has triggered slip along faults in the Salton Trough. Fractures associated with the event formed discontinuous breaks over a 39-km-long stretch of the San Andreas fault, from the Mecca Hills southeastward to Salt Creek and Durmid Hill, a distance from the epicenter of 107 to 139 km. Sense of slip was right lateral; only locally was there a minor (~1 mm) vertical component of slip. Dextral slip ranged from 1 to 13 mm. Maximum slip values in 1999 and earlier triggered slips are most common in the central Mecca Hills. Field evidence indicates a transient opening as the Hector Mine seismic waves passed the southern San Andreas fault. Comparison of nearby strong-motion records indicates several periods of relative opening with passage of the Hector Mine seismic wave-a similar process may have contributed to the field evidence of a transient opening. Slip on the Superstition Hills fault extended at least 9 km, at a distance from the Hector Mine epicenter of about 188 to 196 km. This length of slip is a minimum value, because we saw fresh surface breakage extending farther northwest than our measurement sites. Sense of slip was right lateral; locally there was a minor (~1 mm) vertical component of slip. Dextral slip ranged from 1 to 18 mm, with the largest amounts found distributed (or skewed) away from the Hector Mine earthquake source. Slip triggered on the Superstition Hills fault commonly is skewed away from the earthquake source, most notably in 1968, 1979, and 1999. Surface slip on the Imperial fault and within the Imperial Valley extended about 22 km, representing a distance from the Hector Mine epicenter of about 204 to 226 km. Sense of slip dominantly was right lateral; the right-lateral component of slip ranged from 1 to 19 mm. Locally there was a minor (~1-2 mm) vertical component of slip; larger proportions of vertical slip (up to 10 mm) occurred in Mesquite basin, where scarps indicate long-term oblique-slip motion for this part of the Imperial fault. Slip triggered on the Imperial fault appears randomly distributed relative to location along the fault and source direction. Multiple surface slips, both primary and triggered slip, indicate that slip repeatedly is small at locations of structural complexity.

Rymer, M.J.; Boatwright, J.; Seekins, L.C.; Yule, J.D.; Liu, J.

2002-01-01

297

Acromioclavicular joint dislocations.  

PubMed

Acromioclavicular (AC) dislocation is a common injury especially among sportsmen. There is still a lack of consensus on whether to conserve or operate type III AC joint dislocations. Even among surgeons inclined to operate AC joint dislocations there is no unanimity on which surgical technique. There are a plethora of choices between mechanical fixation or synthetic materials or biologic anatomic reconstructions. Even among surgeons, there is a choice between open repairs and the latest-arthroscopic reconstructions. This review of AC joint dislocations intends to analyze the available surgical options, a critical analysis of existing literature, actual technique of anatomic repair, and also accompanying complications. PMID:24431027

Babhulkar, Ashish; Pawaskar, Aditya

2014-03-01

298

Anterior glenohumeral joint dislocations.  

PubMed

The glenohumeral joint is the most mobile articulation in the body and the most commonly dislocated diarthroidal joint. Anterior dislocation is by far the most common direction and can lead to instability of the glenohumeral joint, which ranges from subtle increased laxity to recurrent dislocation. Overtime, understanding of anterior shoulder dislocations and the resulting instability has improved. Likewise, significant advances in arthroscopic equipment have allowed use of the arthroscope to address anatomically the various lesions that cause instability. This article reviews the anatomy, pathophysiology, clinical evaluation, and treatment of anterior shoulder instability. PMID:18803980

Dodson, Christopher C; Cordasco, Frank A

2008-10-01

299

Direct Measurement of the Slip Weakening Distance from Near-Fault Strong Motion Data?  

Microsoft Academic Search

Mikumo et al. (2001, this issue) find from numerical simulations using a planar, vertical shear fault in a slip-weakening rupture model that the slip-weakening distance (Dc) can be estimated reasonably accurately as the slip displacement at the time of the peak slip-velocity Tpv. Here, we examine whether the results by Mikumo et al. can be used to estimate Dc from

K. B. Olsen; E. Fukuyama; T. Mikumo

2001-01-01

300

Slip and Dilation Tendency Analysis of the Patua Geothermal Area  

SciTech Connect

Critically stressed fault segments have a relatively high likelihood of acting as fluid flow conduits (Sibson, 1994). As such, the tendency of a fault segment to slip (slip tendency; Ts; Morris et al., 1996) or to dilate (dilation tendency; Td; Ferrill et al., 1999) provides an indication of which faults or fault segments within a geothermal system are critically stressed and therefore likely to transmit geothermal fluids. The slip tendency of a surface is defined by the ratio of shear stress to normal stress on that surface: Ts = ? / ?n (Morris et al., 1996). Dilation tendency is defined by the stress acting normal to a given surface: Td = (?1-?n) / (?1-?3) (Ferrill et al., 1999). Slip and dilation were calculated using 3DStress (Southwest Research Institute). Slip and dilation tendency are both unitless ratios of the resolved stresses applied to the fault plane by ambient stress conditions. Values range from a maximum of 1, a fault plane ideally oriented to slip or dilate under ambient stress conditions to zero, a fault plane with no potential to slip or dilate. Slip and dilation tendency values were calculated for each fault in the focus study areas at, McGinness Hills, Neal Hot Springs, Patua, Salt Wells, San Emidio, and Tuscarora on fault traces. As dip is not well constrained or unknown for many faults mapped in within these we made these calculations using the dip for each fault that would yield the maximum slip tendency or dilation tendency. As such, these results should be viewed as maximum tendency of each fault to slip or dilate. The resulting along-fault and fault-to-fault variation in slip or dilation potential is a proxy for along fault and fault-to-fault variation in fluid flow conduit potential. Stress Magnitudes and directions Stress field variation within each focus area was approximated based on regional published data and the world stress database (Hickman et al., 2000; Hickman et al., 1998 Robertson-Tait et al., 2004; Hickman and Davatzes, 2010; Davatzes and Hickman, 2006; Blake and Davatzes 2011; Blake and Davatzes, 2012; Moeck et al., 2010; Moos and Ronne, 2010 and Reinecker et al., 2005) as well as local stress information if applicable. For faults within these focus systems we applied either a normal faulting stress regime where the vertical stress (sv) is larger than the maximum horizontal stress (shmax) which is larger than the minimum horizontal stress (sv>shmax>shmin) or strike-slip faulting stress regime where the maximum horizontal stress (shmax) is larger than the vertical stress (sv) which is larger than the minimum horizontal stress (shmax >sv>shmin) depending on the general tectonic province of the system. Based on visual inspection of the limited stress magnitude data in the Great Basin we used magnitudes such that shmin/shmax = .527 and shmin/sv= .46, which are consistent with complete and partial stress field determinations from Desert Peak, Coso, the Fallon area and Dixie valley (Hickman et al., 2000; Hickman et al., 1998 Robertson-Tait et al., 2004; Hickman and Davatzes, 2011; Davatzes and Hickman, 2006; Blake and Davatzes 2011; Blake and Davatzes, 2012). Slip and dilation tendency analysis for the Patua geothermal system was calculated based on faults mapped in the Hazen Quadrangle (Faulds et al., 2011). Patua lies near the margin between the Basin and Range province, which is characterized by west-northwest directed extension and the Walker Lane province, characterized by west-northwest directed dextral shear. As such, the Patua area likely has been affected by tectonic stress associated with either or both of stress regimes over geologic time. In order to characterize this stress variation we calculated slip tendency at Patua for both normal faulting and strike slip faulting stress regimes. Based on examination of regional and local stress data (as explained above) we applied at shmin direction of 105 to Patua. Whether the vertical stress (sv) magnitude is larger than ...

James E. Faulds

2013-12-31

301

Constraints on fault slip rates of the southern California plate boundary from GPS velocity and stress inversions  

USGS Publications Warehouse

We use Global Positioning System (GPS) velocities and stress orientations inferred from seismicity to invert for the distribution of slip on faults in the southern California plate-boundary region. Of particular interest is how long-term slip rates are partitioned between the Indio segment of the San Andreas fault (SAF), the San Jacinto fault (SJF) and the San Bernardino segment of the SAE We use two new sets of constraints to address this problem. The first is geodetic velocities from the Southern California Earthquake Center's (SCEC) Crustal Motion Map (version 3 by Shen et al.), which includes significantly more data than previous models. The second is a regional model of stress-field orientations at seismogenic depths, as determined from earthquake focal mechanisms. While GPS data have been used in similar studies before, this is the first application of stress-field observations to this problem. We construct a simplified model of the southern California fault system, and estimate the interseismic surface velocities using a backslip approach with purely elastic strain accumulation, following Meade et al. In addition, we model the stress orientations at seismogenic depths, assuming that crustal stress results from the loading of active faults. The geodetically derived stressing rates are found to be aligned with the stress orientations from seismicity. We therefore proceed to invert simultaneously GPS and stress observations for slip rates of the faults in our network. We find that the regional patterns of crustal deformation as imaged by both data sets can be explained by our model, and that joint inversions lead to better constrained slip rates. In our preferred model, the SJF accommodates ???15 mm yr-1 and the Indio segment of the SAF ???23 mm yr-1 of right-lateral motion, accompanied by a low slip rate on the San Bernardino segment of the SAF 'Anomalous' fault segments such as around the 1992 Mw = 7.3 Landers surface rupture can be detected. There, observed stresses deviate strongly from the long-term loading as predicted by our simple model. Evaluation of model misfits together with information from palaeoseismology may provide further insights into the time dependence of strain accumulation along the San Andreas system. ?? 2004 RAS.

Becker, T. W.; Hardebeck, J. L.; Anderson, G.

2005-01-01

302

Shallow slip deficit due to large strike-slip earthquakes in dynamic rupture simulations with elasto-plastic off-fault response  

NASA Astrophysics Data System (ADS)

Slip inversions of geodetic data from several large (magnitude ˜7) strike-slip earthquakes point to coseismic slip deficit at shallow depths (<3-4 km), that is, coseismic slip appears to decrease towards the Earth surface. While the inferred slip distribution may be consistent with laboratory-derived rate and state friction laws suggesting that the uppermost brittle crust may be velocity strengthening, there remains a question of how the coseismic slip deficit is accommodated throughout the earthquake cycle. The consequence of velocity-strengthening fault friction at shallow depths is that the deficit of coseismic slip is relieved by post-seismic afterslip and interseismic creep. However, many seismic events with inferred shallow slip deficit were not associated with either resolvable shallow interseismic creep or robust shallow afterslip. Hence, the origin of shallow 'slip deficit' remains uncertain. In this study, we investigate whether inelastic failure in the shallow crust due to dynamic earthquake rupture can explain the inferred deficit of shallow slip. Evidence for such failure is emerging from geologic, seismic and geodetic observations. We find that the amount of shallow slip deficit is proportional to the amount of inelastic deformation near the Earth surface. Such deformation occurs under a wide range of parameters that characterize rock strength in the upper crust. However, the largest magnitude of slip deficit in models accounting for off-fault yielding is 2-4 times smaller than that inferred from kinematic inversions of geodetic data. To explain this discrepancy, we further explore to what extent assumptions in the kinematic inversions may bias the inferred slip distributions. Inelastic deformation in the shallow crust reduces coseismic strain near the fault, introducing an additional 'artificial' deficit of up to 10 per cent of the maximum slip in inversions of geodetic data that are based on purely elastic models. The largest magnitude of slip deficit in our models combined with the bias in inversions accounts for up to 25 per cent of shallow slip deficit, which is comparable, but still smaller than 30-60 per cent deficit inferred from kinematic inversions. We discuss potential mechanisms that may account for the remaining discrepancy between slip deficit predicted by elasto-plastic rupture models and that inferred from inversions of space geodetic data.

Kaneko, Y.; Fialko, Y.

2011-09-01

303

Constraints on fault and lithosphere rheology from the coseismic slip and postseismic afterslip  

E-print Network

Constraints on fault and lithosphere rheology from the coseismic slip and postseismic afterslip plane. An adjacent normal fault segment slipped postseismically (and possibly also co-seismically-slip manner in the crystalline basement, and that where it cuts the sedimentary layer the coseismic rupture

304

Coseismic slip distribution of the February 27, 2010 Mw 8.8 Maule, Chile earthquake  

E-print Network

Coseismic slip distribution of the February 27, 2010 Mw 8.8 Maule, Chile earthquake Fred F. Pollitz by the February 27, 2010 Mw = 8.8 Maule, Chile earthquake as measured by GPS and InSAR constrain coseismic slip at depth 25 km on the megathrust just west of Concepción. Coseismic slip is negligible below 35 km depth

Vigny, Christophe

305

Coseismic slip distribution of the February 27, 2010 Mw 8.8 Maule, Chile earthquake  

E-print Network

Coseismic slip distribution of the February 27, 2010 Mw 8.8 Maule, Chile earthquake Fred F. Pollitz by the February 27, 2010 Mw = 8.8 Maule, Chile earthquake as measured by GPS and InSAR constrain coseismic slip maxi- mum appears at depth 25 km on the megathrust just west of Concepción. Coseismic slip

Socquet, Anne

306

Path Following Control with Slip Compensation on Loose Soil for Exploration Rover  

Microsoft Academic Search

In this paper, a path following control strategy for lunar\\/planetary exploration rovers is described, taking into account slip motion of the rover. It is determined that the slip motion of each wheel of the rover must be increased and cannot be neglected when the rover travels on loose soil. Because of slip, following an arbitrary path on loose soil is

Genya Ishigami; Keiji Nagatani; Kazuya Yoshida

2006-01-01

307

Nonlinear Observer for Bounded Jacobian Systems, With Applications to Automotive Slip Angle Estimation  

Microsoft Academic Search

Real-time knowledge of the slip angle in a vehicle is useful in many active vehicle safety applications, including yaw stability control, rollover prevention, and lane departure avoidance. Sensors that can di- rectly measure slip angle are too expensive for ordinary automotive ap- plications. This technical note develops a new nonlinear observer design technique for estimation of slip angle using inexpensive

Gridsada Phanomchoeng; Rajesh Rajamani; Damrongrit Piyabongkarn

2011-01-01

308

Very high cycle fatigue of copper: Evolution, morphology and locations of surface slip markings  

E-print Network

Very high cycle fatigue of copper: Evolution, morphology and locations of surface slip markings N cycle fatigue Persistent slip bands Grain boundaries Strain localization Fatigue limit The surfaces high cycle fatigue regime were investigated. The stress amplitude needed to form the early slip

Paris-Sud XI, Université de

309

The liquid metal slip ring experiment for the communications technology satellite  

NASA Technical Reports Server (NTRS)

The experiment is designed to demonstrate liquid metal slip ring (LMSR) performance in a space environment. An evaluation was made of the features of the LMSR where improvement in performance over conventional slip rings was expected. The primary measurements to be made in the experiment will allow a determination of the slip ring electrical resistance, between ring insulation and ring cleanliness.

Lovell, R. R.

1972-01-01

310

Geodetic and seismic signatures of episodic tremor and slip in the northern Cascadia subduction zone  

Microsoft Academic Search

Slip events with an average duration of about 10 days and effective total slip displacements of severalc entimetres have been detected on the deeper (25 to 45 km) part of the northern Cascadia subduction zone interface by observing transient surface deformation on a network of continuously recording Global Positioning System (GPS) sites. The slip events occur down-dip from the currently

H. Dragert; K. Wang; G. Rogers

2004-01-01

311

Role of friction-induced torque in stick-slip motion J. Scheibert1,  

E-print Network

Role of friction-induced torque in stick-slip motion J. Scheibert1, and D.K. Dysthe1 1 PGP describing the kinematics of the transition from static friction to stick-slip motion of a linear elastic the precursors to frictional sliding and the periodic stick- slip motion are controlled by the amount of friction

312

Slip and fall risk among firefighters in relation to balance, muscular capacities and age  

Microsoft Academic Search

Influencing the safety of firefighters’ work environment is almost impossible. Therefore, good individual physical capacities and adequate protective equipment are important in preventing accidents due to slips and falls. This study investigated slip and fall risk in walking experiments with firefighters wearing fire-protective equipment and determined the associations of balance, muscular capacities and age with the risk of slipping. Professional

Anne Punakallio; Mikko Hirvonen; Raoul Grönqvist

2005-01-01

313

Early Heelstrike Kinetics Are Indicative of Slip Potential During Walking Over a Contaminated Surface  

Microsoft Academic Search

Objective: The objective of this study is to examine ground kinetics early in stance while walking on a contaminated surface and assess the potential of kinetics to quantify risk of slipping.Background: Prior studies of slipping have dismissed early ground kinetic data, and therefore no prior literature has been able to assess the viability of using these data to quantify slip

Sean T. Osis; Jay T. Worobets; Darren J. Stefanyshyn

2012-01-01

314

Spatiotemporal evolution of a transient slip event on the San Andreas fault near Parkfield, California  

E-print Network

- vations from continuously recording geodetic networks have revealed a growing number of transient faultSpatiotemporal evolution of a transient slip event on the San Andreas fault near Parkfield fault slip. The EDM data cannot resolve whether transient slip propagated across the nucleation zone

Segall, Paul

315

Evidence for Quaternary Slip on a Low Angle Normal Fault: Searles Valley, CA  

Microsoft Academic Search

Low angle normal faults have been documented in extensional terranes worldwide, however conventional models of fault mechanics preclude slip on planes dipping less than 30 degrees. The global catalogue of earthquake focal mechanisms reveals very few occurrences of seismicity (active slip) on low angle structures, lending support to mechanical arguments against active slip on shallowly dipping planes. Recent field studies

T. Numelin; E. Kirby

2004-01-01

316

Improved orthopedic arm joint  

NASA Technical Reports Server (NTRS)

Joint permits smooth and easy movement of disabled arm and is smaller, lighter and less expensive than previous models. Device is interchangeable and may be used on either arm at the shoulder or at the elbow.

Dane, D. H.

1971-01-01

317

Joint Services Electronics Program.  

National Technical Information Service (NTIS)

An annual report of the JSEP (Joint Services Electronics Program) in solid state electronics, quantum electronics, information electronics, control and optimization, and electromagnetic phenomena is presented. Results of the research to date are summarize...

M. Tinkham

1991-01-01

318

Joint Services Electronics Program.  

National Technical Information Service (NTIS)

An annual report of the JSEP (Joint Services Electronics Program) in solid state electronics, quantum electronics, information electronics, control and optimization, and electromagnetic phenomena is presented. Results of the research to date are summarize...

M. Tinkham

1987-01-01

319

Joint Services Electronics Program.  

National Technical Information Service (NTIS)

An annual report of the JSEP (Joint Services Electronic Program) in solid state electronics, quantum electronics, information electronics control and optimization and electromagnetic phenomenon is presented. Results of the research to date are summarized ...

M. Tinkham

1985-01-01

320

JOINT SEMINAR FINAL REPORT  

E-print Network

evolving from the Joint Seminar. - Peer-reviewed publications (journals, contribution to anthologies, working papers, proceedings, etc.) - Non peer-reviewed publications (journals, contribution to anthologies Application guidelines Length Clarity Intelligibility Procedures (submission, review, decision) Advising

Fuchs, Clemens

321

Culture - joint fluid  

MedlinePLUS

Joint fluid culture ... fungi, or viruses grow. This is called a culture. If such microorganisms are detected, other tests may ... is no special preparation needed for the lab culture. For information on preparing for the removal of ...

322

Analysis of the slow slip events of Guerrero, Mexico: implications for numerical modeling.  

NASA Astrophysics Data System (ADS)

Guerrero, in Mexico, is one of the subduction zones where long term slow slip events (SSEs) have been observed recurrently. Understanding the mechanics of these events is important to determine their role in the seismic cycle. SSEs in Guerrero have been found to have the same characteristics, along the interface of subduction, as classical earthquakes but with much longer slip time (around a year) and lower stress drop (0.1 MPa). We investigate the slip models of the Guerrero SSEs of 2006 and 2009 (Radiguet et al., JGR 2012). The kinematic slip models have been determined by inversion of GPS time series using two different methods. From these slip histories, the constitutive relation between stress and slip (or slip rate) on each subfault is determined. Analytical Green functions are used to calculate the shear stress in a homogeneous, elastic, isotropic medium. Whatever the kinematic slip modeling method used, a clear slip weakening law can be retrieved over the whole slipping area. While some spatial variation in the parameters of the slip weakening law is observed, a mean value of about 0.1 m for the slip weakening distance and 2.5 kJ/m2 for the fracture energy can be extracted on each subfault. Moreover the slip-weakening rate seems quite homogeneous (around 1 MPa/m), and this is roughly the same as the value found in coseismic processes. The yield stress is of the order of 0.01 MPa, a low value compared to a stress drop of 0.1 MPa. The stress-slip rate relationship presents a loop trajectory coherent with the one observed in classical earthquakes. The results of these analyses are used to numerically model the Guerrero SSEs. The aim is to reproduce the slip pattern using the mechanical laws determined in the study of the slip model. If a simple slip weakening law, with parameters found above, is used, we observe a rapid progress of the crack-like slip area. This is different from the observation of the migration of localized slip. So a slowing mechanism (healing) must be introduced in addition to the slip weakening law. A pseudo-dynamic model is developed, supposing a fully plastic fault strengthening with a prefixed slip distance.

Maury, Julie; Aochi, Hideo; Radiguet, Mathilde

2014-05-01

323

Slow slip events and seismic tremor at circum-Pacific subduction zones  

NASA Astrophysics Data System (ADS)

It has been known for a long time that slip accompanying earthquakes accounts for only a fraction of plate tectonic displacements. However, only recently has a fuller spectrum of strain release processes, including normal, slow, and silent earthquakes (or slow slip events) and continuous and episodic slip, been observed and generated by numerical simulations of the earthquake cycle. Despite a profusion of observations and modeling studies the physical mechanism of slow slip events remains elusive. The concurrence of seismic tremor with slow slip episodes in Cascadia and southwestern Japan provides insight into the process of slow slip. A perceived similarity between subduction zone and volcanic tremor has led to suggestions that slow slip involves fluid migration on or near the plate interface. Alternatively, evidence is accumulating to support the notion that tremor results from shear failure during slow slip. Global observations of the location, spatial extent, magnitude, duration, slip rate, and periodicity of these aseismic slip transients indicate significant variation that may be exploited to better understand their generation. Most slow slip events occur just downdip of the seismogenic zone, consistent with rate- and state-dependent frictional modeling that requires unstable to stable transitional properties for slow slip generation. At a few convergent margins the occurrence of slow slip events within the seismogenic zone makes it highly likely that transitions in frictional properties exist there and are the loci of slow slip nucleation. Slow slip events perturb the surrounding stress field and may either increase or relieve stress on a fault, bringing it closer to or farther from earthquake failure, respectively. This paper presents a review of slow slip events and related seismic tremor observed at plate boundaries worldwide, with a focus on circum-Pacific subduction zones. Trends in global observations of slow slip events suggest that (1) slow slip is a common phenomena observed at almost all subduction zones with instrumentation capable of recording it, (2) different frictional properties likely control fast versus slow slip, (3) the depth range of slow slip may be related to the thermal properties of the plate interface, and (4) the equivalent seismic moment of slow slip events is proportional to their duration (Mo??), different from the Mo??3 scaling observed for earthquakes.

Schwartz, Susan Y.; Rokosky, Juliana M.

2007-09-01

324

Slip and Dilation Tendency Analysis of the Tuscarora Geothermal Area  

SciTech Connect

Critically stressed fault segments have a relatively high likelihood of acting as fluid flow conduits (Sibson, 1994). As such, the tendency of a fault segment to slip (slip tendency; Ts; Morris et al., 1996) or to dilate (dilation tendency; Td; Ferrill et al., 1999) provides an indication of which faults or fault segments within a geothermal system are critically stressed and therefore likely to transmit geothermal fluids. The slip tendency of a surface is defined by the ratio of shear stress to normal stress on that surface: Ts = ? / ?n (Morris et al., 1996). Dilation tendency is defined by the stress acting normal to a given surface: Td = (?1-?n) / (?1-?3) (Ferrill et al., 1999). Slip and dilation were calculated using 3DStress (Southwest Research Institute). Slip and dilation tendency are both unitless ratios of the resolved stresses applied to the fault plane by ambient stress conditions. Values range from a maximum of 1, a fault plane ideally oriented to slip or dilate under ambient stress conditions to zero, a fault plane with no potential to slip or dilate. Slip and dilation tendency values were calculated for each fault in the focus study areas at, McGinness Hills, Neal Hot Springs, Patua, Salt Wells, San Emidio, and Tuscarora on fault traces. As dip is not well constrained or unknown for many faults mapped in within these we made these calculations using the dip for each fault that would yield the maximum slip tendency or dilation tendency. As such, these results should be viewed as maximum tendency of each fault to slip or dilate. The resulting along-fault and fault-to-fault variation in slip or dilation potential is a proxy for along fault and fault-to-fault variation in fluid flow conduit potential. Stress Magnitudes and directions Stress field variation within each focus area was approximated based on regional published data and the world stress database (Hickman et al., 2000; Hickman et al., 1998 Robertson-Tait et al., 2004; Hickman and Davatzes, 2010; Davatzes and Hickman, 2006; Blake and Davatzes 2011; Blake and Davatzes, 2012; Moeck et al., 2010; Moos and Ronne, 2010 and Reinecker et al., 2005) as well as local stress information if applicable. For faults within these focus systems we applied either a normal faulting stress regime where the vertical stress (sv) is larger than the maximum horizontal stress (shmax) which is larger than the minimum horizontal stress (sv>shmax>shmin) or strike-slip faulting stress regime where the maximum horizontal stress (shmax) is larger than the vertical stress (sv) which is larger than the minimum horizontal stress (shmax >sv>shmin) depending on the general tectonic province of the system. Based on visual inspection of the limited stress magnitude data in the Great Basin we used magnitudes such that shmin/shmax = .527 and shmin/sv= .46, which are consistent with complete and partial stress field determinations from Desert Peak, Coso, the Fallon area and Dixie valley (Hickman et al., 2000; Hickman et al., 1998 Robertson-Tait et al., 2004; Hickman and Davatzes, 2011; Davatzes and Hickman, 2006; Blake and Davatzes 2011; Blake and Davatzes, 2012). Slip and dilation tendency for the Tuscarora geothermal field was calculated based on the faults mapped Tuscarora area (Dering, 2013). The Tuscarora area lies in the Basin and Range Province, as such we applied a normal faulting stress regime to the Tuscarora area faults, with a minimum horizontal stress direction oriented 115, based on inspection of local and regional stress determinations, as explained above. Under these stress conditions north-northeast striking, steeply dipping fault segments have the highest dilation tendency, while north-northeast striking 60° dipping fault segments have the highest tendency to slip. Tuscarora is defined by a left-step in a major north- to-north northeast striking, west-dipping range-bounding normal fault system. Faults within the broad step define an anticlinal accommodation zone...

James E. Faulds

2013-12-31

325

Joint hypermobility syndrome pain  

Microsoft Academic Search

Joint hypermobility syndrome (JHS) was initially defined as the occurrence of musculoskeletal symptoms in the presence of\\u000a joint laxity and hypermobility in otherwise healthy individuals. It is now perceived as a commonly overlooked, underdiagnosed,\\u000a multifaceted, and multisystemic heritable disorder of connective tissue (HDCT), which shares many of the phenotypic features\\u000a of other HDCTs such as Marfan syndrome and Ehlers-Danlos syndrome.

Rodney Grahame

2009-01-01

326

Panel Post & Diagonal Brace Joint Detail; Crossbracing Center Joint ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Panel Post & Diagonal Brace Joint Detail; Crossbracing Center Joint Detail; Chord, Panel Post, Tie Bar, & Diagonal Brace Joint Detail; Chord, Tie Bar, & Crossbracing Joint Detail - Medora Bridge, Spanning East Fork of White River at State Route 235, Medora, Jackson County, IN

327

High pressure ceramic joint  

DOEpatents

Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present joint when used with recuperators increases the use of ceramic components which do not react to highly corrosive gases. Thus, the present joint used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present joint is comprised of a first ceramic member, a second ceramic member, a mechanical locking device having a groove defined in one of the first ceramic member and the second ceramic member. The joint and the mechanical locking device is further comprised of a refractory material disposed in the groove and contacting the first ceramic member and the second ceramic member. The present joint mechanically provides a high strength load bearing joint having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures.

Ward, Michael E. (Poway, CA); Harkins, Bruce D. (San Diego, CA)

1993-01-01

328

Assembly Of The SLIP1-SLBP Complex On Histone mRNA Requires Heterodimerization And Sequential Binding Of SLBP Followed By SLIP1  

PubMed Central

The SLIP1-SLBP complex activates translation of replication-dependent histone mRNAs. In this report, we describe how the activity of the SLIP1-SLBP complex is modulated by phosphorylation and oligomerization. Biophysical characterization of the free proteins shows that whereas SLIP1 is a homodimer that does not bind RNA, human SLBP is an intrinsically disordered protein that is phosphorylated at 23 Ser/Thr sites when expressed in a eukaryotic expression system such as baculovirus. The bacterially expressed unphosphorylated SLIP1-SLBP complex forms a 2:2 high affinity (KD < 0.9 nM) heterotetramer that is also incapable of binding histone mRNA. In contrast, phosphorylated SLBP from baculovirus has weak affinity (KD ~3 µM) for SLIP1. Sequential binding of phosphorylated SLBP to the histone mRNA stem-loop, followed by association with SLIP1 is required to form an “active” ternary complex. Phosphorylation of SLBP at Thr171 promotes dissociation of the heterotetramer to the SLIP1-SLBP heterodimer. Using alanine scanning mutagenesis we demonstrate that the binding site on SLIP1 for SLBP lies close to the dimer interface. A single point mutant near the SLIP1 homodimer interface abolished interaction with SLBP in vitro and reduced histone mRNA abundance in vivo. On the basis of these biophysical studies, we propose that oligomerization and SLBP phosphorylation may regulate the SLBP-SLIP1 complex in vivo. SLIP1 may act to sequester SLBP in vivo protecting it from proteolytic degradation as an inactive hetero-tetramer, or alternatively, formation of the SLIP1-SLBP hetero-tetramer may facilitate removal of SLBP from the histone mRNA prior to histone mRNA degradation. PMID:23286197

Bansal, Nitin; Zhang, Minyou; Bhaskar, Aishwarya; Itotia, Patrick; Lee, EunHee; Shlyakhtenko, Lyudmila S; Lam, TuKiet T.; Fritz, Andrew; Berezney, Ronald; Lyubchenko, Yuri L; Stafford, Walter F.; Thapar, Roopa

2013-01-01

329

The Slumgullion Natural Laboratory for Observing Slip Phenomena  

NASA Astrophysics Data System (ADS)

Many natural systems release stresses by failure and sliding across surfaces; examples include landslides, glaciers, crustal- and plate-scale faults. Observational advances continue to reveal diversity in the seismic signals associated with fault slip and how such stress relaxation can occur, even on a single fault system. A particularly rich example are the episodes of slow fault slip near major subduction and transform plate boundaries that manifest as geodetically observed aseismic deformation abetted by a family of seismic signals depleted in high-frequencies relative to those from earthquakes (named ‘episodic tremor and slip’ or ETS). While the driving forces and scales differ, there are striking parallels between some observations and models of ETS and of landslide behaviors; e.g. in both, postulated key controls include rate-dependent friction and strength modulated by pore-pressure changes, dilatancy during rapid shear, and subsequent consolidation. To explore common features and the underlying processes we are studying the Slumgullion landslide, an ideal natural laboratory for observing fault slip and associated seismic and aseismic phenomena. Unlike crustal- or plate-scale studies significant deformation can be measured within a single field season, because the Slumgullion moves at average rates of cm/day. Moreover, pore pressures, displacements, material properties, and environmental variables may be measured directly and continuously at several locations on the landslide (albeit not at the basal sliding surface). We have just completed a field experiment on the Slumgullion to test several hypotheses, particularly that slip along the basal surface and side-bounding faults occurs with comparable richness of aseismic and seismic modes as crustal- and plate-scale boundaries. To do so from August 18-26, 2009 we continuously monitored the displacement-field using a robotic electronic displacement meter and the seismic radiation with 88 vertical-component seismographs [see Bodin et al., companion abstract]. Although we have only begun examining the data thus far, the seismic data contain an abundance of network-wide coherent signals with an amazing variety of characteristics. Significant unsteady movement in the displacement field is evident in the geodetic data, as well as fluctuations in the pore-pressures and relevant environmental parameters. Schulz et al. (companion abstract) presents initial landslide observations. We will form and present implications for understanding the likely mechanisms of failure and slip within natural systems.

Gomberg, J. S.; Schulz, W. H.; Bodin, P.; Kean, J. W.; Wang, G.; Coe, J. A.; MacQueen, P.; Foster, K.; Creager, K.

2009-12-01

330

Probabilistic estimates of surface coseismic slip and afterslip for Hayward fault earthquakes  

USGS Publications Warehouse

We examine the partition of long?term geologic slip on the Hayward fault into interseismic creep, coseismic slip, and afterslip. Using Monte Carlo simulations, we compute expected coseismic slip and afterslip at three alinement array sites for Hayward fault earthquakes with nominal moment magnitudes ranging from about 6.5 to 7.1. We consider how interseismic creep might affect the coseismic slip distribution as well as the variability in locations of large and small slip patches and the magnitude of an earthquake for a given rupture area. We calibrate the estimates to be consistent with the ratio of interseismic creep rate at the alinement array sites to the geologic slip rate for the Hayward fault. We find that the coseismic slip at the surface is expected to comprise only a small fraction of the long?term geologic slip. The median values of coseismic slip are less than 0.2 m in nearly all cases as a result of the influence of interseismic creep and afterslip. However, afterslip makes a substantial contribution to the long?term geologic slip and may be responsible for up to 0.5–1.5 m (median plus one standard deviation [S.D.]) of additional slip following an earthquake rupture. Thus, utility and transportation infrastructure could be severely impacted by afterslip in the hours and days following a large earthquake on the Hayward fault that generated little coseismic slip. Inherent spatial variability in earthquake slip combined with the uncertainty in how interseismic creep affects coseismic slip results in large uncertainties in these slip estimates.

Aagaard, Brad T.; Lienkaemper, James J.; Schwartz, David P.

2012-01-01

331

Self-healing slip pulses in dynamic rupture models due to velocity-dependent strength  

USGS Publications Warehouse

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 point. In contrast, some seismological evidence suggests that the duration of slip is too short for waves to propagate from the nearest edge of the ruptured surface, perhaps even if the distance used is an asperity size instead of the entire rupture dimension. What controls slip duration, if not dimensions of the fault or of asperities? In this study, dynamic earthquake rupture and slip are represented by a propagating shear crack. For all propagating shear cracks, slip velocity is highest near the rupture front, and at a small distance behind the rupture front, the slip velocity decreases. As pointed out by Heaton (1990), if the crack obeys a negative slip-rate-dependent strength relation, the lower slip velocity behind the rupture front will lead to strengthening that further reduces the velocity, and under certain circumstances, healing of slip can occur. The boundary element method of Hamano (1974) is used in a program adapted from Andrews (1985) for numerical simulations of mode II rupture with two different velocity-dependent strength functions. For the first function, after a slip-weakening displacement, the crack follows an exponential velocity-weakening relation. The characteristic velocity V0 of the exponential determines the magnitude of the velocity-dependence at dynamic velocities. The velocity-dependence at high velocity is essentially zero when V0 is small and the resulting slip velocity distribution is similar to slip weakening. If V0 is larger, rupture propagation initially resembles slip-weakening, but spontaneous healing occurs behind the rupture front. The rise time and rupture propagation velocity depend on the choice of constitutive parameters. The second strength function is a natural log velocity-dependent form similar to constitutive laws that fit experimental rock friction data at lower velocities. Slip pulses also arise with this function. For a reasonable choice of constitutive parameters, slip pulses with this function do not propagate at speeds greater than the Raleighwave velocity. The calculated slip pulses are similar in many aspects to seismic observations of short rise time. In all cases of self-healing slip pulses, the residual stress increases with distance behind the trailing edge of the pulse so that the final stress drop is much less than the dynamic stress drop, in agreement with the model of Brune (1976) and some recent seismological observations of rupture.

Beeler, N.M.; Tullis, T.E.

1996-01-01

332

Slip history of the 1995 Kobe, Japan, earthquake determined from strong motion, teleseismic, and geodetic data  

USGS Publications Warehouse

Near-source ground motions, teleseismic body waveforms, and geodetic displacements produced by the 1995 Kobe, Japan, earthquake have been used to determine the spatial and temporal dislocation pattern on the faulting surfaces. Analysis of the slip model indicates that the ground motions recorded within the severely damaged region of Kobe originated from the region of relatively low slip (about 1 m) deep beneath Kobe and not from the shallow, higher slip regions (about 3 m) beneath Aqaji Island. Although the slip was relatively low beneath Kobe, the combined effects of source rupture directivity, a short slip duration, and site amplification conspired to generate very damaging ground motions within the city.

Wald, D.J.

1996-01-01

333

Coseismic Slip Distribution of the 2002 Mw7.9 Denali Fault Earthquake  

NASA Astrophysics Data System (ADS)

We have estimated coseismic displacements for the 2002 Mw7.9 Denali Fault Earthquake at 232 GPS sites in Alaska and Canada, 180 of them within one rupture length of the earthquake. The displacement field shows a typical right-lateral deformation pattern for an E-W trending fault that cuts the surface. In general sites SW and NE of the fault move away from the fault and subside, but sites NW and SE of the fault move toward the fault and rise. Displacements along a N-S profile, crossing the fault along the Trans-Alaska Pipeline, indicate right-lateral slip on a near vertical fault with a significant component of vertical motion, north side up. These observations are in agreement with typical geological surface offset measurements along the Denali Fault (Haeussler et al., in press 2004). We estimated slip on a 3D fault model using a bounded variable least squares inversion, allowing only right-lateral strike slip and north-side-up dip slip. Allowing for oblique slip along the Denali and Totschunda faults improves the model fit to the GPS data by about 30%. We see mostly right lateral strike-slip motion on the Denali and Totschunda fault but in few areas we see a significant component of dip slip. The slip model shows increasing slip from west to east along the Denali Fault, with a few higher-slip patches. We infer maximum slip (9-12 m) about 40 km west of the Denali-Totschunda junction. This coincides with where geological observations estimated maximum slip of 8.8 m. Slip of 1-3 m was estimated along the Totschunda fault with majority of the slip being at shallower than 9 km depth. We have limited resolution on the Susitna Glacier fault but the estimated slip along the fault is consistent with a Mw7.2 sub-thrust-event. Total moment release in the Denali earthquake is Mw7.90, assuming a rigidity of 30 GPa. The estimated slip distribution along the surface is in very good agreement with geological surface offset measurements not measured on glaciers, but we find that surface offsets measured on glaciers are biased to lower values. We use the geological surface data, ignoring data from glaciers, to further constrain slip at the surface. This additional data set gives us important information on slip on shallower portions of the fault where we lack near field GPS data. The resulting slip model gives a similar but more refined slip distribution, with Mw7.89.

Hreinsdöttir, S.; Freymueller, J.; Burgmann, R.; Mitchell, J.

2004-12-01

334

Rupture history of the 2009 L'Aquila (Italy) earthquake from non-linear joint inversion of strong motion and GPS data  

NASA Astrophysics Data System (ADS)

We image the rupture history of the 2009 L'Aquila (central Italy) earthquake using a nonlinear joint inversion of strong motion and GPS data. This earthquake ruptured a normal fault striking along the Apennines axis and dipping to the SW. The inferred slip distribution is heterogeneous and characterized by a small, shallow slip patch located up-dip from the hypocenter (9.5 km depth) and a large, deeper patch located southeastward. The rupture velocity is larger in the up-dip than in the along-strike direction. This difference can be partially accounted by the crustal structure, which is characterized by a high velocity layer above the hypocenter and a lower velocity below. The latter velocity seems to have affected the along strike propagation since the largest slip patch is located at depths between 9 and 14 km. The imaged slip distribution correlates well with the on-fault aftershock pattern as well as with mapped surface breakages.

Cirella, A.; Piatanesi, A.; Cocco, M.; Tinti, E.; Scognamiglio, L.; Michelini, A.; Lomax, A.; Boschi, E.

2009-10-01

335

High-voltage Milberger slip slide power conditioner  

NASA Astrophysics Data System (ADS)

A high-voltage converter circuit uses a slip slide power conditioner to reduce non-monotonic non-linearities in the converter output signal is disclosed. The slip slide power conditioner includes: a choke feed dc circulator; two radio frequency (RF) power pumps; a phase detector; a phase controller; and a combiner. The choke feed dc circulator receives the dc input signal and produces therefrom two voltage output signals which are each sent to one of the two RF power pumps. The two RF power pumps produce two out-of-phase square wave output signals which are algebraically combined in the combiner to form an output signal whose amplitude is a function of phase difference. The phase detector and phase controller sample this output signal and adjust the phase of the two power pumps to remove non-linearities due to secondary ranging (resonance) that beats with harmonics of their square wave signals.

Jones, Franklin B.

1986-08-01

336

Large Scale Structure as a Probe of Gravitational Slip  

E-print Network

A new time-dependent, scale-independent parameter, \\varpi, is employed in a phenomenological model of the deviation from General Relativity in which the Newtonian and longitudinal gravitational potentials slip apart on cosmological scales as dark energy, assumed to be arising from a new theory of gravitation, appears to dominate the universe. A comparison is presented between \\varpi and other parameterized post-Friedmannian models in the literature. The effect of \\varpi on the cosmic microwave background anisotropy spectrum, the growth of large scale structure, the galaxy weak-lensing correlation function, and cross-correlations of cosmic microwave background anisotropy with galaxy clustering are illustrated. Cosmological models with conventional maximum likelihood parameters are shown to find agreement with a narrow range of gravitational slip.

Scott F. Daniel; Robert R. Caldwell; Asantha Cooray; Alessandro Melchiorri

2008-02-07

337

A silent slip event on the deeper Cascadia subduction interface.  

PubMed

Continuous Global Positioning System sites in southwestern British Columbia, Canada, and northwestern Washington state, USA, have been moving landward as a result of the locked state of the Cascadia subduction fault offshore. In the summer of 1999, a cluster of seven sites briefly reversed their direction of motion. No seismicity was associated with this event. The sudden displacements are best explained by approximately 2 centimeters of aseismic slip over a 50-kilometer-by-300-kilometer area on the subduction interface downdip from the seismogenic zone, a rupture equivalent to an earthquake of moment magnitude 6.7. This provides evidence that slip of the hotter, plastic part of the subduction interface, and hence stress loading of the megathrust earthquake zone, can occur in discrete pulses. PMID:11313500

Dragert, G; Wang, K; James, T S

2001-05-25

338

Liquid water can slip on a hydrophilic surface  

PubMed Central

Understanding and predicting the behavior of water, especially in contact with various surfaces, is a scientific challenge. Molecular-level understanding of hydrophobic effects and their macroscopic consequences, in particular, is critical to many applications. Macroscopically, a surface is classified as hydrophilic or hydrophobic depending on the contact angle formed by a water droplet. Because hydrophobic surfaces tend to cause water slip whereas hydrophilic ones do not, the former surfaces can yield self-cleaning garments and ice-repellent materials whereas the latter cannot. The results presented herein suggest that this dichotomy might be purely coincidental. Our simulation results demonstrate that hydrophilic surfaces can show features typically associated with hydrophobicity, namely liquid water slip. Further analysis provides details on the molecular mechanism responsible for this surprising result. PMID:21911406

Ho, Tuan Anh; Papavassiliou, Dimitrios V.; Lee, Lloyd L.; Striolo, Alberto

2011-01-01

339

Toward a Unified View of Tremor and Slow Slip  

NASA Astrophysics Data System (ADS)

Evidence from Japan suggests that deep non-volcanic tremor consists of myriad Low Frequency Earthquakes (LFEs) on the subduction interface, with focal mechanisms consistent with plate convergence [Shelly et al., Nature 2007; Ide et al., GRL 2007]. Thus I adopt the view that tremor and the accompanying slow slip represent two manifestations of slip on the same interface, and that they should be explainable using the same constitutive framework. Here I explore various incarnations of rate-and-state (r-s) friction. Episodic slow slip may result from (1) a transition from velocity-weakening to velocity-strengthening behavior at less than slow-slip speeds [Kato, EPSL 2003; Shibazaki and Iio, GRL 2003]; (2) "standard" r-s friction, meaning with velocity-independent material parameters, on a fault whose length is properly "tuned" and that possesses high pore pressure (low effective stress) [Liu and Rice, JGR 2005; 2007], or (3) fault-zone dilatancy coupled with pore pressure reduction and diffusion [Segall and Rubin, EOS, 2007]. Using the most appropriate laboratory constitutive law it seems that (2) requires too much "tuning" [Rubin, JGR, in press], but many aspects of slow slip events, including their low stress drop (~10 kPa in Cascadia and Japan), are most easily explained by effective stresses as low as 1 MPa. This is consistent with expectations from seismology and petrology, and with the sensitivity of tremor to tides and surface waves. LFE's are most simply interpreted as resulting from material heterogeneity that makes their source region more seismogenic than the surroundings, for which embarrassingly many options exist. The largest LFE's in Japan appear to have magnitudes about 1.5 but durations roughly 10 times longer than "typical" M1.5 earthquakes. A fundamental question is "what makes them slow?". Two answers are (1) elastodynamics and (2) something else. For circular ruptures moment is proportional to stress drop and the radius cubed, so for circular earthquakes rate-limited by elastodynamics a factor of 10 increase in duration can be explained by a factor of 1000 decrease in stress drop. This seems unreasonable, but a factor of 100 decrease (so a factor of 5 increase in duration) is not, if the LFE stress drop is the same 10 kPa as the slow slip stress drop. This is within striking distance of the observations, and if this explains tremor, the question becomes "where are the M2, 3, and 4 elastodynamic events that would be expected of a typical Gutenberg-Richter distribution?". One possibility is that there is a characteristic length scale for slip in the tremor source region [Watanabe et al., GRL 2007], which would be of order 300 m for a 10-kPa M1.5 event. A potential length scale is the "compaction length" that arises during porous flow in a viscously-deforming matrix. A second possibility is that LFE moment is only weakly sensitive to the size of the underlying heterogeneity. Colliding creep waves increase the slip speed locally by multiple orders of magnitude, and for some constitutive laws might give rise to this insensitivity. Such a tremor source is appealing because creep waves arise in all sorts of simulations that include material heterogeneity. It could also give rise to spatially-elongate LFE sources, which might help explain some aspects of their spectra as well as allow larger stress drops for the same duration. If LFE's are rate-limited by "something else", then the question becomes "What process can reasonably increase the speed of >105 sources to the point that they radiate detectable energy, without letting them slide or propagate fast enough to be limited by elastodynamics?". At the moment, "slow but elastodynamic" seems like the most promising line of investigation.

Rubin, A. M.

2008-12-01

340

Solute effect on basal and prismatic slip systems of Mg.  

PubMed

In an effort to design novel magnesium (Mg) alloys with high ductility, we present a first principles data based on the Density Functional Theory (DFT). The DFT was employed to calculate the generalized stacking fault energy curves, which can be used in the generalized Peierls-Nabarro (PN) model to study the energetics of basal slip and prismatic slip in Mg with and without solutes to calculate continuum scale dislocation core widths, stacking fault widths and Peierls stresses. The generalized stacking fault energy curves for pure Mg agreed well with other DFT calculations. Solute effects on these curves were calculated for nine alloying elements, namely Al, Ca, Ce, Gd, Li, Si, Sn, Zn and Zr, which allowed the strength and ductility to be qualitatively estimated based on the basal dislocation properties. Based on our multiscale methodology, a suggestion has been made to improve Mg formability. PMID:25273695

Moitra, Amitava; Kim, Seong-Gon; Horstemeyer, M F

2014-11-01

341

Solute effect on basal and prismatic slip systems of Mg  

NASA Astrophysics Data System (ADS)

In an effort to design novel magnesium (Mg) alloys with high ductility, we present a first principles data based on the Density Functional Theory (DFT). The DFT was employed to calculate the generalized stacking fault energy curves, which can be used in the generalized Peierls–Nabarro (PN) model to study the energetics of basal slip and prismatic slip in Mg with and without solutes to calculate continuum scale dislocation core widths, stacking fault widths and Peierls stresses. The generalized stacking fault energy curves for pure Mg agreed well with other DFT calculations. Solute effects on these curves were calculated for nine alloying elements, namely Al, Ca, Ce, Gd, Li, Si, Sn, Zn and Zr, which allowed the strength and ductility to be qualitatively estimated based on the basal dislocation properties. Based on our multiscale methodology, a suggestion has been made to improve Mg formability.

Moitra, Amitava; Kim, Seong-Gon; Horstemeyer, M. F.

2014-11-01

342

Insights into Wasatch fault vertical slip rates using the age of sediments in Timpanogos Cave, Utah  

NASA Astrophysics Data System (ADS)

Timpanogos Cave, located near the Wasatch fault, is about 357 m above the American Fork River. Fluvial cave sediments and an interbedded carbonate flowstone yield a paleomagnetic and U-Th depositional age of 350 to 780 ka. Fault vertical slip rates, inferred from calculated river downcutting rates, range between 1.02 and 0.46 mm yr - 1 . These slip rates are in the range of the 0-12 Ma Wasatch Range exhumation rate (˜ 0.5-0.7 mm yr - 1 ), suggesting that the long-term vertical slip rate remained stable through mid-Pleistocene time. However, the late Pleistocene (0-250 ka) decelerated slip rate (˜ 0.2-0.3 mm yr - 1 ) and the accelerated Holocene slip rate (˜ 1.2 mm yr - 1 ) are consistent with episodic fault activity. Assuming that the late Pleistocene vertical slip rate represents an episodic slowing of fault movement and the long-term (0-12 Ma) average vertical slip rate, including the late Pleistocene and Holocene, should be ˜ 0.6 mm yr - 1 , there is a net late Pleistocene vertical slip deficit of ˜ 50-75 m. The Holocene and late Pleistocene slip rates may be typical for episodes of accelerated and slowed fault movement, respectively. The calculated late Pleistocene slip deficit may mean that the current accelerated Wasatch fault slip rate will extend well into the future.

Mayo, Alan L.; Bruthans, Jiri; Tingey, David; Kadlec, Jaroslav; Nelson, Steve

2009-09-01

343

Imaging coseismic rupture in far field by slip patches  

Microsoft Academic Search

Since the end of the 1970s, teleseismic waves are used routinely to infer the first-order characteristics of the event (location, depth, duration, focal mechanism), but finding the second-order kinematic parameters (spatial distribution of slip, rupture velocity and more basically the discrimination between the fault plane and the other nodal plane) of distant events remains a difficult task. Classically, these events

M. Vallée; M. Bouchon

2004-01-01

344

Coseismic slip distribution of the 1923 Kanto earthquake, Japan  

Microsoft Academic Search

The slip distribution associated with the 1923 M = 7.9 Kanto, Japan, earthquake is reexamined in light of new data and modeling. We utilize a combination of first-order triangulation, second-order triangulation, and leveling data in order to constrain the coseismic deformation. The second-order triangulation data, which have not been utilized in previous studies of 1923 coseismic deformation, are associated with

Fred F. Pollitz; Marleen Nyst; Takuya Nishimura; Wayne Thatcher

2005-01-01

345

Slip inversion on complex fault surfaces using angular elastic dislocations  

Microsoft Academic Search

We present a new 3D slip-inversion method based on the analytical solution of an angular dislocation in a linear-elastic, homogeneous, isotropic, whole- or half-space. The approach uses a boundary element method (BEM) that employs planar triangular elements of constant displacement to model fault surfaces. Discretization of surfaces into triangular boundary elements allows the construction of complex 3D fault surfaces with

F. Maerten; L. Maerten; P. Resor

2002-01-01

346

Review of Episodic Tremor and Slip in Cascadia  

Microsoft Academic Search

Episodic Tremor and Slip (ETS) has now been observed over much of the Cascadia subduction zone, including regions within the main Juan de Fuca Plate segment, the Explorer Plate and Gorda Plate segments at the northern and southern ends respectively. The non-earthquake, tremor-like seismic signals have frequency content between 1-6 Hz, last anywhere from tens of seconds to hours, are

S. Malone; G. Rogers; H. Dragert; W. McCausland; D. Johnson

2004-01-01

347

Seismicity distribution near strike-slip faults in California  

Microsoft Academic Search

Hypocenters of small, relocated earthquakes are used to constrain how seismicity rates vary with distance from strike-slip faults in California. Stacks of events in a fault-referenced coordinate system show that out to a fault-normal distance x of 3-6 km, seismicity obeys a power-law ˜ (1+ x2\\/d 2)-gamma\\/2, where gamma is the asymptotic roll-off rate and d is a near-fault inner

Peter Marion Powers

2009-01-01

348

Normal Stress and Gaps in Interacting Strike-Slip Faults  

Microsoft Academic Search

One of the pressing issues in seismic hazard analysis is the probability of earthquake rupture jumping between fault segments, resulting in a large cascading event. Researchers (e.g., Wesnousky, 2006) have conducted observational surveys to determine the maximum width of stepover that rupture may jump in strike-slip systems, and other researchers (e.g., Harris et al., 1991; Kase and Kuge, 1998; Harris

D. D. Oglesby

2007-01-01

349

Unsteady Couette flow of a micropolar fluid with slip  

Microsoft Academic Search

The unsteady Couette flow of an isothermal incompressible micropolar fluid between two infinite parallel plates is investigated.\\u000a The motion of the fluid is produced by a time-dependent impulsive motion of the lower plate while the upper plate is set at\\u000a rest. A linear slip, of Basset type, boundary condition on both plates is used. Two particular cases are discussed; in the

E. A. Ashmawy

350

Variations in strength and slip rate along the san andreas fault system.  

PubMed

Convergence across the San Andreas fault (SAF) system is partitioned between strike-slip motion on the vertical SAF and oblique-slip motion on parallel dip-slip faults, as illustrated by the recent magnitude M(s) = 6.0 Palm Springs, M(s) = 6.7 Coalinga, and M(s) = 7.1 Loma Prieta earthquakes. If the partitioning of slip minimizes the work done against friction, the direction of slip during these recent earthquakes depends primarily on fault dip and indicates that the normal stress coefficient and frictional coefficient (micro) vary among the faults. Additionally, accounting for the active dip-slip faults reduces estimates of fault slip rates along the vertical trace of the SAF by about 50 percent in the Loma Prieta and 100 percent in the North Palm Springs segments. PMID:17802597

Jones, C H; Wesnousky, S G

1992-04-01

351

Slip-velocity and drag of large neutrally-buoyant particles in turbulent flows  

E-print Network

We discuss possible definitions for a slip velocity that describes the relative motion between large particles and a turbulent flow. This definition is necessary because the slip velocity used in the standard drag model fails when particle size falls within the inertial subrange of ambient turbulence. By decomposing drag into steady and stochastic components, we obtain both a steady slip velocity and a fluctuating slip velocity. From this decomposition, we propose two definitions for stochastic slip velocity. These definitions were selected in part due to their simplicity: they do not require filtration of the fluid phase velocity field, nor do they require the construction of conditional averages on particle locations. A key benefit of this simplicity is that the stochastic slip velocity proposed here can be calculated equally well for laboratory, field, and numerical experiments. The stochastic slip velocity allows the definition of a Reynolds number that should indicate whether large particles in turbulent...

Bellani, Gabriele

2012-01-01

352

Stick-slip advance of the Kohat Plateau in Pakistan  

NASA Astrophysics Data System (ADS)

Throughout most of the Himalaya, slip of the Indian Plate is restrained by friction on the interface between the plate and the overlying wedge of Himalayan rocks. Every few hundred years, this interface--or décollement--ruptures in one or more Mw >=8 earthquakes. In contrast, in the westernmost Himalaya, the Indian Plate slips aseismically beneath wide plateaux fronting the Kohistan Mountains. The plateaux are underlain by viscous décollements that are unable to sustain large earthquakes. Potwar, the widest of these plateaux is underlain by viscous salt, which currently permits it to slide at rates of about 3mmyr-1 (refs , ), much slower than its 2 Myr average. This deceleration has been attributed to recently increased friction through the loss of salt from its décollement. Here we use interferometric synthetic aperture radar and seismic data to assess movement of the Kohat Plateau--the narrowest and thickest plateau. We find that in 1992 an 80 km2 patch of the décollement ruptured in a rare Mw 6.0 earthquake, suggesting that parts of the décollement are locally grounded. We conclude that this hybrid seismic and aseismic behaviour represents an evolution of the mode of slip of the plateaux from steady creep towards increasingly widespread seismic rupture.

Satyabala, S. P.; Yang, Zhaohui; Bilham, Roger

2012-02-01

353

Distribution of strike-slip faults on Europa  

NASA Astrophysics Data System (ADS)

Study of four different regions on Europa imaged by the Galileo spacecraft during its first 15 orbits has revealed 117 strike-slip faults. Europa appears to form preferentially right-lateral faults in the southern hemisphere and left-lateral faults in the northern hemisphere. This observation is consistent with a model where diurnal tides due to orbital eccentricity drive strike-slip motion through a process of ``walking,'' in which faults open and close out of phase with alternating right-and left-lateral shear. Lineaments that record both left-and right-lateral motion (e.g., Agave Linea) may record the accommodation of compression in nearby chaotic zones. Nearly all identified strike-slip faults were associated with double ridges or bands, and few were detected along ridgeless cracks. Thus the depth of cracks without ridges does not appear to have penetrated to the low-viscosity decoupling layer, required for diurnal displacement, but cracks that have developed ridges do extend down to such a level. This result supports a model for ridge formation that requires cracks to penetrate to a decoupling layer, such as a liquid water ocean.

Hoppa, Gregory; Greenberg, Richard; Tufts, B. Randall; Geissler, Paul; Phillips, Cynthia; Milazzo, Moses

2000-09-01

354

Interfacial Slip in Melt Rheology of Immiscible Polymer Blends  

NASA Astrophysics Data System (ADS)

The linear viscoelastic behavior of immiscible polymer blends can be modeled by considering the properties of each phase and interfacial tension (Palierne, 1990). However, at high stresses a number of researchers have reported an anomalous lowering of polymer blend viscosity. We have verified these observations with blends of polypropylene (PP) and polystyrene (PS). The temperature and molecular weight of the homopolymers were selected such that their viscosities were closely matched. The dynamic shear viscosity of the blends was the same as that of the homopolymers, but the steady shear viscosity was lower and the deviation greater with increasing stress up to about 5X104 Pa. Rheological measurements on layered structures also showed lower viscosity with increased number of layers and with increased stress indicating slip at the PP-PS interfaces. These apparent slip viscosities are significantly higher than predicted by Goveas and Fredrickson (1998). Adding a block copolymer which is expected to span the interface appeared to reduce the slip in the blends as well as layered stretch.

Zhao, Rui; Macosko, Christopher

2000-03-01

355

A plea for more caution in fault-slip analysis  

NASA Astrophysics Data System (ADS)

The analysis of fault-slip data is a widely used tool in structural geology. This method consists of three major steps: (a) data acquisition by measurements in outcrops, (b) data separation into homogeneous subsets and calculation of the principal stress or strain axes with one of several available methods, and (c) data interpretation in a regional tectonic context, which includes the assignment of ages and the derivation of regional patterns. Each one of these three steps may introduce artefacts and misinterpretations. The major problem during step (a) is sampling bias due to unfavourable outcrop geometry or due to neglecting faults with subtle slip-sense indicators. Step (b) contains numerous possibilities to influence the calculation results, e.g. by arbitrary separation of data into subsets, choice of the analysis method, and uncritical use of software. Age assignment in step (c) can in most cases be made only indirectly, e.g. by the assumption that measured outcrop-scale faults have the same age as parallel map-scale faults or by the inference that subsets from different sites with parallel-oriented principal axes are syngenetic. Neither assumption is necessarily valid. With this paper we want to sharpen researchers' awareness of the problems related to fault-slip analysis.

Sperner, Blanka; Zweigel, Peter

2010-02-01

356

Dissimilar metals joint evaluation  

NASA Technical Reports Server (NTRS)

Dissimilar metals tubular joints between 2219-T851 aluminum alloy and 304L stainless steel were fabricated and tested to evaluate bonding processes. Joints were fabricated by four processes: (1) inertia (friction) weldings, where the metals are spun and forced together to create the weld; (2) explosive welding, where the metals are impacted together at high velocity; (3) co-extrusion, where the metals are extruded in contact at high temperature to promote diffusion; and (4) swaging, where residual stresses in the metals after a stretching operation maintain forced contact in mutual shear areas. Fifteen joints of each type were prepared and evaluated in a 6.35 cm (2.50 in.) O.D. size, with 0.32 cm (0.13 in.) wall thickness, and 7.6 cm (3.0 in) total length. The joints were tested to evaluate their ability to withstand pressure cycle, thermal cycle, galvanic corrosion and burst tests. Leakage tests and other non-destructive test techniques were used to evaluate the behavior of the joints, and the microstructure of the bond areas was analyzed.

Wakefield, M. E.; Apodaca, L. E.

1974-01-01

357

Distal radioulnar joint injuries  

PubMed Central

Distal radioulnar joint is a trochoid joint relatively new in evolution. Along with proximal radioulnar joint, forearm bones and interosseous membrane, it allows pronosupination and load transmission across the wrist. Injuries around distal radioulnar joint are not uncommon, and are usually associated with distal radius fractures,fractures of the ulnar styloid and with the eponymous Galeazzi or Essex_Lopresti fractures. The injury can be purely involving the soft tissue especially the triangular fibrocartilage or the radioulnar ligaments. The patients usually present with ulnar sided wrist pain, features of instability, or restriction of rotation. Difficulty in carrying loads in the hand is a major constraint for these patients. Thorough clinical examination to localize point of tenderness and appropriate provocative tests help in diagnosis. Radiology and MRI are extremely useful, while arthroscopy is the gold standard for evaluation. The treatment protocols are continuously evolving and range from conservative, arthroscopic to open surgical methods. Isolated dislocation are uncommon. Basal fractures of the ulnar styloid tend to make the joint unstable and may require operative intervention. Chronic instability requires reconstruction of the stabilizing ligaments to avoid onset of arthritis. Prosthetic replacement in arthritis is gaining acceptance in the management of arthritis. PMID:23162140

Thomas, Binu P; Sreekanth, Raveendran

2012-01-01

358

Periprosthetic Joint Infections  

PubMed Central

Implantation of joint prostheses is becoming increasingly common, especially for the hip and knee. Infection is considered to be the most devastating of prosthesis-related complications, leading to prolonged hospitalization, repeated surgical intervention, and even definitive loss of the implant. The main risk factors to periprosthetic joint infections (PJIs) are advanced age, malnutrition, obesity, diabetes mellitus, HIV infection at an advanced stage, presence of distant infectious foci, and antecedents of arthroscopy or infection in previous arthroplasty. Joint prostheses can become infected through three different routes: direct implantation, hematogenic infection, and reactivation of latent infection. Gram-positive bacteria predominate in cases of PJI, mainly Staphylococcus aureus and Staphylococcus epidermidis. PJIs present characteristic signs that can be divided into acute and chronic manifestations. The main imaging method used in diagnosing joint prosthesis infections is X-ray. Computed tomography (CT) scan may assist in distinguishing between septic and aseptic loosening. Three-phase bone scintigraphy using technetium has high sensitivity, but low specificity. Positron emission tomography using fluorodeoxyglucose (FDG-PET) presents very divergent results in the literature. Definitive diagnosis of infection should be made by isolating the microorganism through cultures on material obtained from joint fluid puncturing, surgical wound secretions, surgical debridement procedures, or sonication fluid. Success in treating PJI depends on extensive surgical debridement and adequate and effective antibiotic therapy. Treatment in two stages using a spacer is recommended for most chronic infections in arthroplasty cases. Treatment in a single procedure is appropriate in carefully selected cases. PMID:24023542

Lima, Ana Lucia L.; Oliveira, Priscila R.; Carvalho, Vladimir C.; Saconi, Eduardo S.; Cabrita, Henrique B.; Rodrigues, Marcelo B.

2013-01-01

359

Improved ceramic slip casting technique. [application to aircraft model fabrication  

NASA Technical Reports Server (NTRS)

A primary concern in modern fluid dynamics research is the experimental verification of computational aerothermodynamic codes. This research requires high precision and detail in the test model employed. Ceramic materials are used for these models because of their low heat conductivity and their survivability at high temperatures. To fabricate such models, slip casting techniques were developed to provide net-form, precision casting capability for high-purity ceramic materials in aqueous solutions. In previous slip casting techniques, block, or flask molds made of plaster-of-paris were used to draw liquid from the slip material. Upon setting, parts were removed from the flask mold and cured in a kiln at high temperatures. Casting detail was usually limited with this technique -- detailed parts were frequently damaged upon separation from the flask mold, as the molded parts are extremely delicate in the uncured state, and the flask mold is inflexible. Ceramic surfaces were also marred by 'parting lines' caused by mold separation. This adversely affected the aerodynamic surface quality of the model as well. (Parting lines are invariably necessary on or near the leading edges of wings, nosetips, and fins for mold separation. These areas are also critical for flow boundary layer control.) Parting agents used in the casting process also affected surface quality. These agents eventually soaked into the mold, the model, or flaked off when releasing the case model. Different materials were tried, such as oils, paraffin, and even an algae. The algae released best, but some of it remained on the model and imparted an uneven texture and discoloration on the model surface when cured. According to the present invention, a wax pattern for a shell mold is provided, and an aqueous mixture of a calcium sulfate-bonded investment material is applied as a coating to the wax pattern. The coated wax pattern is then dried, followed by curing to vaporize the wax pattern and leave a shell mold of the calcium sulfate-bonded investment material. The shell mold is cooled to room temperature, and a ceramic slip is poured therein. After a ceramic shell of desired thickness has set up in the shell mold, excess ceramic slip is poured out. While still wet, the shell mold is peeled from the ceramic shell to expose any delicate or detailed parts, after which the ceramic shell is cured to provide a complete, detailed, precision ceramic article without parting lines.

Buck, Gregory M. (inventor); Vasquez, Peter (inventor)

1993-01-01

360

Coseismic slip, post-seismic slip, and aftershocks associated with two large earthquakes in 1996 in Hyuga-nada, Japan  

Microsoft Academic Search

We analyzed continuous GPS data to investigate the spatial distribution of post-seismic slip associated with two large earthquakes of October 19 and December 2, 1996, in Hyuga-nada, Japan. We found that the moment release due to post-seismic events was comparable to the co-seismic moment release during the two earthquakes. The source parameters of the first post-seismic event are as follows:

Yuji Yagi; Masayuki Kikuchi; Takeshi Sagiya

2001-01-01

361

The assessment of the integration of slip resistance, thermal insulation and wearability of footwear on icy surfaces  

Microsoft Academic Search

Prevention of slip hazard in frozen environments is not paid much attention. Current winter and safety footwear does not provide sufficient slip resistance and appropriate wearability for use on icy surfaces. The objectives of this study were to assess the integration of slip resistance, thermal insulation, and wearability of footwear used on icy surfaces, and the anti-slip effect of materials

Chuansi Gao; John Abeysekera

2002-01-01

362

Comparison of surface slip and focal mechanism slip data along normal faults: an example from the eastern Gulf of Corinth, Greece  

Microsoft Academic Search

Focal mechanism and surface slip data are used to investigate whether kinematics are similar at depth and at the surface along an active normal fault in the Gulf of Corinth, Greece. We present a new database of slip data from the lateral termination of the South Alkyonides fault segment (SAFS) and the en échelon stepover between it and an adjacent

Nigel C. Morewood; Gerald P. Roberts

2001-01-01

363

Structural and sedimentary characteristics of the Liangjia-Wangchang strike-slip region, Yitong Basin, China  

NASA Astrophysics Data System (ADS)

The Yitong Basin, a typical strike-slip basin, is part of the northern segment of the world-famous Tanlu strike-slip fault area in China. Research is needed to understand how the strike-slip tectonic environment affects the development of structures and depositional systems within the basin. The aim of this paper is to analyze how the right-lateral strike-slip movement of the northwestern boundary faults in this region controls extensional faulting, and to analyze differences in two main sedimentary sequences (termed SYSQ1 and SYSQ2) that result from strike-slip movement. The study is based on geological and geophysical data. The following conclusions are drawn: (1) The two periods of strike-slip movement of the boundary fault generated two episodes of extensional fault inside the basin. The extensional faults have a characteristically episodic activity related to the episodic strike-slip movement. The extensional faults have small fault throw, and their activity lags behind the strike-slip movement of the northwestern boundary faults. (2) The strike-slip movement of the boundary faults generated the extensional faults inside the basin and changed the locus of depocenters, with complimentary changes in the paleogeomorphology and in the distribution of depositional facies. It is this strike-slip movement that caused the differences in sedimentary and structural characteristics between sequences SYSQ1 and SYSQ2.

Shi, Wanzhong; Cartwright, Joe; Zhao, Zhikui; Chen, Honghan; Jiang, Tao; Miao, Hongbo; Wang, Xiaolong

2012-05-01

364

Squeaking with a sliding joint: mechanics and motor control of sound production in palinurid lobsters.  

PubMed

The origin of arthropod sound-producing morphology typically involves modification of two translating body surfaces, such as the legs and thorax. In an unusual structural rearrangement, I show that one lineage of palinurid lobsters lost an antennal joint articulation, which transformed this joint from moving with one degree of freedom into a sliding joint with multiple degrees of freedom. With this sliding joint, 'stick-and-slip' sounds are produced by rubbing the base of each antenna against the antennular plate. To understand the musculo-skeletal changes that occurred during the origin and evolutionary variation of this sound-producing mechanism, I examined joint morphology and antennal muscle anatomy across sound-producing and non-sound-producing palinurids. Plectrum movement and antennal muscle activity were measured in a sound-producing species, Panulirus argus. The promotor muscle pulls the plectrum over the file during sound-producing and non-sound-producing movements; a higher intensity of muscle activity is associated with sound production. The promotor muscle is larger and attaches more medially in sound-producing palinurids than in non-sound producers. In Panulirus argus, each shingle on the file has an additional ridge; in Palinurus elephas, the shingle surfaces are smooth. These differences in shingle surface features suggest variation in the stick-and-slip properties of the system. Translational motion permitted by the sliding joint is necessary for sound production; hence, the construction of a sliding joint is a key modification in the origin of this sound-producing mechanism. PMID:12124363

Patek, Sheila N

2002-08-01

365

Surface Melt Produced on Faults During Laboratory Stick-slip Experiments  

NASA Astrophysics Data System (ADS)

Melt coated most of the fault surface on dry, bare, room-temperature granite faults as a result of stick-slip in triaxial loading at 400 MPa confining pressure. Saw-cut surfaces, inclined 30 degrees to the sample axis, were prepared by lapping with 600 grit SiC. Dynamic weakening during stick-slip caused total stress drops that ranged from 250-350 MPa shear stress (peak normal stress was 550-600 MPa) with fault-parallel slip from 2.0 to 2.8 mm. The resulting melt layers are estimated to be 5-40 microns thick and for multiple stick-slip events show evidence of re-worked glassy material. In contrast, repeated stick-slip cycles at 50 MPa confining pressure and a cumulative 9 mm displacement produced fine-grained fault gouge but showed no evidence of surface melting. At 50 MPa, stress drops were typically 35 percent, peak shear and normal stresses were approximately 66 and 88 MPa, respectively, and fault-parallel slip was about 0.14 mm. With recent interest in determining frictional properties of rock at coseismic slip speeds, a variety of high-speed rotary testing machines have been developed that allow for large total slip. Since maximum fault surface temperature depends, in part, on the product: (shear stress) x (slip speed) x (slip duration), these rotary machines can achieve high surface temperatures at modest normal stress. However, evidence for dynamic heating and surface weakening in laboratory stick-slip experiments was reported more than 30 years ago using triaxial test machines, although the observations at that time were not conclusive. By operating at normal stresses 10 to 20 times greater that those used in unconfined rotary machines, triaxial stick-slip experiments are able to develop high transient surface temperatures that include pseudotachylite formation, even with limited total slip.

Lockner, D. A.; Moore, D. E.; Beeler, N. M.; Kilgore, B. D.

2010-12-01

366

Evolving flexible joint morphologies  

Microsoft Academic Search

Transferring virtual robotic designs into physical robots has become possible with the development of 3D printers. Accurately simulating the performance of real robots in a virtual environment requires modeling a variety of conditions, including the physical composition of the robots themselves. In this paper, we investigate how modeling material flexibility through the use of a passive joint affects the resulting

Jared M. Moore; Philip K. McKinley

2012-01-01

367

Joint Durability The problem?  

E-print Network

;Interfacial Zone? #12;Walking a Cliff Edge · In situ air content · w/cm · Saturation · Salts #12;Base Permeability #12;An Example #12;So · Water has to be prevented from saturating the concrete · Prevent water from ponding in the joint · Prevent water from penetrating from the base · Permeability of the concrete

368

Coseismic and cumulative slip along the Kokoxili Mw 7.9 earthquake rupture (Kunlun Fault, northeastern Tibet)  

Microsoft Academic Search

Co-seismic slip values along a strike-slip rupture are found to be very irregular with variations up to one order of magnitude. Data usually scattered and sparse, are more dense and continuous with slip functions derived from InSAR or image correlations. Whether the fast variations in slip along strike reveals long-lived structures of the fault plane at depth, only incomplete slip

J. van der Woerd; Y. Klinger; X. Xu; K. Ledortz; P. Tapponnier; H. Li; G. King; W. Ma; W. Chen

2009-01-01

369

Joints in a Cornstarch Analog  

NSDL National Science Digital Library

Joints are very important to problems in applied geology (fluid flow, slope stability), but three-dimensional exposures of simple joint sets are not readily accessible from my campus. I developed this exercise based on the experiments of Miller (2001) to give students hands-on practice describing and interpreting joints. For the exercise, I prepare a cornstarch-water mixture a few days in advance and pour it into plastic petri dishes. I add a "flaw" to each dish (typically a small pebble). As the cornstarch dries, vertical joints develop. In class, each group of 3-4 students is provided a petri dish of desiccated cornstarch. Students are asked to draw a map of the joints, paying particular attention to intersection angles. (The joints curve to intersect at 90 degrees.) They determine relative ages of the joints using abutting relationships. (Typically 3-6 generations of joints.) Students next dissect the sample and describe the surface textures of the larger joints and the location of the flaw. The cornstarch produces beautiful plumose structure (hackles). Students then interpret the joint propagation direction from the surface textures, and note the origin of the joint. (Typically, a first- or second-generation joint initiates at the flaw.) Students discuss the role of flaws in the initiation of joints in their groups.

Crider, Juliet

370

Self-healing slip pulse on a frictional surface  

NASA Astrophysics Data System (ADS)

Guided by seismic observations of short-duration radiated pulses in earthquake ruptures, Heaton (1990) has postulated a mechanism for the frictional sliding of two identical elastic solids that consists in the subsonic propagation of a self-healing slip velocity pulse of finite duration along the interface. The same type of pulse may be conjectured for inhomogeneous slip along sufficiently large, and compliant, technological surfaces. We analyze such pulses, first as steady traveling waves which move at constant speed, and without alteration of shape, on the interface between joined elastic half-spaces, and later as transient disturbances along such an interface, arising as slip rupture propagates spontaneously from an over-stressed nucleation site. The study is conducted in the framework of antiplane elastodynamics; normal stress is uniform and alteration of it is not considered. We show that not all constitutive models allow for steady traveling wave pulses: the static friction threshold subsequent to the relocking of the fault must increase with time. That is, such solutions do not exist for pure velocity-dependent constitutive models, in which the stress-resisting slip on the ruptured surface is a continuously decreasing function of the instantaneous sliding rate (but not of its previous history or of other measures of the evolving state of the surface). Further, even for constitutive models that include both the rate- and state-dependence of friction, such as the laboratory-based constitutive models for friction as developed by Dieterich (1979, 1981) and Ruina (1983), steady pulse solutions do not exist for versions, like one discussed by Ruina (1983), which do not allow (rapid) restrengthening in truly stationary contact. For a particular class of rate- and state-dependent laws which includes such restrengthening, we establish parameter ranges for which steady pulse solutions exist, and use a numerical method stabilized by a Tikhonov-style regularization to construct the solutions. The numerical method used for the transient analysis adopts Fourier series representations for the spatial dependence of stress and slip along the interface, with the (time-dependent) coefficients in those Fourier series being related to one another in a way which obtains from exact solution to the equations of elastodynamics. This allows an efficient numerical method, based on use of the Fast Fourier Transform in each time step, with the frictional constitutive law enforced at the FFT sample points along the interface. Solutions based on a law that includes restrengthening in stationary contact show that spontaneous rupture propagation will occur either in the self-healing slip pulse mode (but not generally as a steady pulse) or in the classical enlarging-crack mode, depending on the values of parameters which enter the constitutive law. This analysis suggests that the strictly steady, traveling wave pulse solutions may either be unstable or have a limited basin of attraction.

Perrin, Gilles; Rice, James R.; Zheng, Gutuan

1995-09-01

371

Seismic Slip on an Oblique Detachment Fault at Low Angles  

NASA Astrophysics Data System (ADS)

Pseudotachylytes are one of the few accepted indicators of seismic slip along ancient faults. Low-angle normal faults have produced few large earthquakes in historic times and low-angle normal faults (detachment faults) are typically severely misoriented relative to a vertical maximum compressive stress. As a result many geoscientists question whether low-angle normal faults produce earthquakes at low angles. Relationships in southern California show that a major low-angle normal-oblique fault slipped at low angles and produced large earthquakes. The exhumed Late Cenozoic West Salton detachment fault preserves spectacular fault- related pseudotachylytes along its fault plane and injected into its hanging wall and footwall. Composite pseudotachylyte zones are up to 1.25 m thick and persists over lateral distances of at least 10's of meters. Pseudotachylyte is common in most thin sections of damaged fault rocks with more than 20% (by volume) of cataclasite. We recognized the presence of original melt using numerous criteria: abundant spherulites in thin sections, injection structures at both the thin-section and outcrop scale, black aphanitic textures, quenched vein margins, variations in microcrystallite textures and/or size with respect to the vein margin, and glassy textures in hand sample. Multiple earthquakes are inferred to produce the layered "stratigraphy" in some exposures of pseudotachylytes. We infer that the West Salton detachment fault formed and slipped at low angles because it nearly perfectly reactivates a Cretaceous ductile thrust system at the half km scale and dips between 10 and 45 degrees. The about 30 degree NNE dip of the detachment fault on the north side of Yaqui Ridge is likely steeper than its dip during detachment slip because there is local steepening on the flanks of the Yaqui Ridge antiform in a contractional stepover of a crosscutting Quaternary San Felipe dextral fault zone. These relationships indicate a low dip on the detachment fault when the detachment was active, when it produced voluminous pseudotachylyte during eartquakes, and when the supradetachment basin above it received a large volume of sediment eroded from the pseudotachylyte-bearing parts of the damage zone. To interpret the pseudotachylyte as the product of slip across a detachment when it was dipping at least 45 degrees requires a sequence of events that is so unlikely that we reject it. There must have been seismic slip at low dip angles across the West Salton detachment fault. Our conclusion agrees with prior studies by John and Axen in the Chemehuevi and Whipple metamorphic core complex and increases the published catalogue of detachment faults that sport pseudotachylytes. These data document that low-angle normal faults are seismogenic, and that conditions that allow pseudotachylytes to form may occur at shallow levels in the crust.

Janecke, S. U.; Steely, A. N.; Evans, J. P.

2008-12-01

372

MIGRATION DES JOINTS DE GRAINS LA MIGRATION DES JOINTS INTERGRANULAIRES  

E-print Network

MIGRATION DES JOINTS DE GRAINS LA MIGRATION DES JOINTS INTERGRANULAIRES O. DIMITROV Centre d nombre de faits fondamentaux concernant la migration des joints de grains sont brièvement rappelés considérant les forces qui provoquent ou qui freinent la migration. L'évolution des modèles proposés pour

Boyer, Edmond

373

Decoupled Control of Flexure Jointed Hexapods Using Estimated Joint Space  

E-print Network

1 Decoupled Control of Flexure Jointed Hexapods Using Estimated Joint Space Mass-Inertia Matrix of flexure jointed hexapods (or Stewart platforms), a new decoupling method is proposed. The new decoupling. Keywords Vibration isolation, decoupling control, Stewart platform, precision robots, hexapod, symmetric

Chen, Yixin

374

Determining the causes of fault slip rate variability for Northern Apennine thrusts on intermediate timescales  

NASA Astrophysics Data System (ADS)

Documenting fault slip rate variability on intermediate (10^4-10^5 yr) timescales is crucial for understanding the process-linkages of short-term (10^1-10^3 yr) and long-term (10^6 yr) patterns of deformation; however, the lack of long records of fault slip with 10^4-10^5 yr resolution presents a major barrier to understanding the underlying process responsible for slip rate variability at those timescales. Taking advantage of spectacular, continuous exposure of growth strata, we document 10^4-10^5 yr resolution records of unsteady fault slip for the past 3.0 myr for three unconnected, shallow blind thrust anticlines growing along the Northern Apennine mountain front, Italy. Fault slip rates for these thrusts were determined from progressive restorations of marine and continental growth strata deposited on the anticlinal limbs. These restorations were supported by subsurface corre-lations of the measured growth sections in order to constrain the fold geometries and kin-ematics. Magnetostratigraphy, cyclostratigraphy, cosmogenic radionuclide (CRN) burial dating, and optically stimulated luminescence (OSL) burial dating provided the high-resolution age models for the growth sections. Slip histories determined from our pro-gressive restorations indicate that all three of the thrust faults exhibited high-frequency slip rate variability. This variability is typically manifest by longer periods of decelerated fault slip punctuated by shorter periods of accelerated fault slip, typically lasting between 80-200 kyr. During times when slip rates were slow, growth strata geometries show ac-celerated slip was accommodated by more foreland structures, suggesting slip partitioning at 10^4-10^5 yr timescales. This high frequency variability is superimposed on a low frequency slip rate variability manifest by an overall deceleration in slip on the shallow thrusts since 3.0 myr. Major decelerations in slip rates were coincident with the activation of thick-skinned thrusting in the Apennines, representing a dynamic reorganization of the Apennine wedge. This suggests two separate causes for slip rate variability on Apennines thrusts: a high-frequency variability that is likely due to processes internal to the wedge, such as slip partitioning, and a low frequency variability that is probably caused by exter-nal forces affecting the entire Apennine wedge.

Gunderson, K. L.; Anastasio, D. J.; Pazzaglia, F. J.

2012-12-01

375

Interchange Slip-Running Reconnection and Sweeping SEP-Beams  

NASA Technical Reports Server (NTRS)

We present a new model to explain how particles, accelerated at a reconnection site that is not magnetically connected to the Earth, could eventually propagate along the well-connected open flux tube. Our model is based on the results of a low-beta resistive magnetohydrodynamics simulation of a three-dimensional line-tied and initially current-free bipole, that is embedded in a non-uniform open potential field. The topology of this configuration is that of an asymmetric coronal null-point, with a closed fan surface and an open outer spine. When driven by slow photospheric shearing motions, field lines, initially fully anchored below the fan dome, reconnect at the null point, and jump to the open magnetic domain. This is the standard interchange mode as sketched and calculated in 2D. The key result in 3D is that, reconnected open field lines located in the vicinity of the outer spine, keep reconnecting continuously, across an open quasi-separatrix layer, as previously identified for non-open-null-point reconnection. The apparent slipping motion of these field lines leads to form an extended narrow magnetic flux tube at high altitude. Because of the slip-running reconnection, we conjecture that if energetic particles would be travelling through, or be accelerated inside, the diffusion region, they would be successively injected along continuously reconnecting field lines that are connected farther and farther from the spine. At the scale of the full Sun, owing to the super-radial expansion of field lines below 3 solar radius, such energetic particles could easily be injected in field lines slipping over significant distances, and could eventually reach the distant flux tube that is well-connected to the Earth.

Masson, S.; Aulanier, G.; Pariat, E.; Klein, K.-L.

2011-01-01

376

Distribution of seismicity across strike-slip faults in California  

NASA Astrophysics Data System (ADS)

The distribution of seismicity about strike-slip faults provides measurements of fault roughness and damage zone width. In California, seismicity decays with distance from strike-slip faults according to a power law ˜(1 + x2/d2)-?/2. This scaling relation holds out to a fault-normal distance x of 3-6 km and is compatible with a "rough fault loading" model in which the inner scale d measures the half width of a volumetric damage zone and the roll-off rate ? is governed by stress variations due to fault roughness. According to Dieterich and Smith's 2-D simulations, ? approximates the fractal dimension of along-strike roughness. Near-fault seismicity is more localized on faults in northern California (NoCal, d = 60 ± 20 m, ? = 1.65 ± .05) than in southern California (SoCal, d = 220 ± 40 m, ? = 1.16 ± .05). The Parkfield region has a damage zone half width (d = 120 ± 30 m) consistent with the SAFOD drilling estimate; its high roll-off rate (? = 2.30 ± .25) indicates a relatively flat roughness spectrum: ˜k-1 versus k-2 for NoCal, k-3 for SoCal. Our damage zone widths (the first direct estimates averaged over the seismogenic layer) can be interpreted in terms of an across-strike "fault core multiplicity" that is ˜1 in NoCal, ˜2 at Parkfield, and ˜3 in SoCal. The localization of seismicity near individual faults correlates with cumulative offset, seismic productivity, and aseismic slip, consistent with a model in which faults originate as branched networks with broad, multicore damage zones and evolve toward more localized, lineated features with low fault core multiplicity, thinner damage zones, and less seismic coupling. Our results suggest how earthquake triggering statistics might be modified by the presence of faults.

Powers, Peter M.; Jordan, Thomas H.

2010-05-01

377

Shoulder Joint For Protective Suit  

NASA Technical Reports Server (NTRS)

Shoulder joint allows full range of natural motion: wearer senses little or no resisting force or torque. Developed for space suit, joint offers advantages in protective garments for underwater work, firefighting, or cleanup of hazardous materials.

Kosmo, Joseph J.; Smallcombe, Richard D.

1994-01-01

378

Rolling contact orthopaedic joint design  

E-print Network

Arthroplasty, the practice of rebuilding diseased biological joints using engineering materials, is often used to treat severe arthritis of the knee and hip. Prosthetic joints have been created in a "biomimetic" manner to ...

Slocum, Alexander Henry, Jr

2013-01-01

379

Slow earthquakes coincident with episodic tremors and slow slip events.  

PubMed

We report on the very-low-frequency earthquakes occurring in the transition zone of the subducting plate interface along the Nankai subduction zone in southwest Japan. Seismic waves generated by very-low-frequency earthquakes with seismic moment magnitudes of 3.1 to 3.5 predominantly show a long period of about 20 seconds. The seismicity of very-low-frequency earthquakes accompanies and migrates with the activity of deep low-frequency tremors and slow slip events. The coincidence of these three phenomena improves the detection and characterization of slow earthquakes, which are thought to increase the stress on updip megathrust earthquake rupture zones. PMID:17138867

Ito, Yoshihiro; Obara, Kazushige; Shiomi, Katsuhiko; Sekine, Shutaro; Hirose, Hitoshi

2007-01-26

380

Braiding Simulation and Slip Evaluation for Arbitrary Mandrels  

NASA Astrophysics Data System (ADS)

Braiding is a manufacturing process that is increasingly being used to manufacture pre-forms for Resin Transfer Moulding. A fast simulation method is presented for the prediction of the fibre distribution on complex braided parts and complex kinetic situations (e.g. changes in velocity, orientation). The implementation is suited for triangular surface representations as generated by many CAD software packages in use. Experimental results show that the results are sensitive to the friction conditions in particular regions. The friction conditions between the yarns and the mandrel are analysed, leading to the development of a slip indicator.

Akkerman, Remko; Villa Rodríguez, Blasimir Hadir

2007-04-01

381

No-Slip Hydrodynamic Boundary Condition for Hydrophilic Particles  

NASA Astrophysics Data System (ADS)

We describe measurement and interpretation of the force acting on a smooth hydrophilic glass particle during rapid (1 100?ms-1) approach to, and separation from, a hydrophilic glass plate in viscous concentrated aqueous sucrose solutions (0.001Passlip boundary condition, even at maximum strain rates of up to 250000s-1. Compared to earlier studies of hydrodynamic forces on small particles, we reduce the uncertainty in the absolute particle-plate separation by using an evanescent-wave measurement of the separation.

Honig, Christopher D. F.; Ducker, William A.

2007-01-01

382

Dynamic slip velocity correlation using non-spherical particles  

E-print Network

RECOMMENDATIONS NOMENCLATURE REFERENCES APPENDIX A . 1 2 6 11 13 15 15 25 31 31 36 42 43 45 47 APPENDIX B . Page 57 113 LIST OF FIGURES FIGURE 1: DRAG COEFFICIENT VS. PARTICLE REYNOLDS NUMBER FOR VARIOUS SHAPED PARTICLES FIGURE 2...: C VS. N?~ FOR DIFFERENT SPHERICITIES USING THE EXPERIMENTAL CORRELATION FIGURE 15 Q VS N~p THE FINAL CORRELATION FOR USE IN ESTIMATING SLIP VELOCITY FIGURE 16: FLUID RHEOLOGY CURVE FOR 1. 0 LB/BBL. HEC IN CARTESIAN COORDINATES FIGURE 17: FLUID...

Pecore, Douglas Wilkin

2012-06-07

383

Surgery for slipped capital femoral epiphysis in adolescents.  

PubMed

The treatment of slipped capital femoral epiphysis (SCFE) in adolescents remains controversial. The goal of initial treatment is to prevent further slippage of the epiphysis. In mild forms, both stable and unstable, in situ fixation is widely accepted as the reference treatment. In contrast, several techniques are available for stable moderate-to-severe SCFE. In unstable moderate-to-severe SCFE, emergent reduction with decompression and internal fixation is currently the preferred method. Selection of the surgical technique rests on an appraisal of advantages versus drawbacks. The goal of this review is to discuss the various surgical methods available for SCFE in adolescents. PMID:24397949

Abu Amara, S; Leroux, J; Lechevallier, J

2014-02-01

384

Blasius boundary layer solution with slip flow conditions  

NASA Astrophysics Data System (ADS)

As the number of applications of micro electro mechanical systems, or MEMS, increase, the variety of flow geometries that must be analyzed at the micro-scale is also increasing. To date, most of the work on MEMS scale fluid mechanics has focused on internal flow geometries, such as microchannels. As applications such as micro-scale flyers are considered, it is becoming necessary to consider external flow geometries. Adding a slip-flow condition to the Blasius boundary layer allows these flows to be studied without extensive computation.

Martin, Michael J.; Boyd, Iain D.

2001-08-01

385

Method of reducing the green density of a slip cast article  

DOEpatents

The method disclosed in this specification is one of reducing the green density of an article cast in a slip casting operation. The article is cast from a casting slip containing silicon metal particles, yttrium containing particles, and a small amount of a fluoride salt which is effective to suppress flocculation of the silicon metal particles by y.sup.+3 ions derived from the yttrium containing particles. The method is characterized by the following step. A small amount of compound which produces a cation which will partly flocculate the particles of silicon metal is added to the casting slip. The small amount of this compound is added so that when the casting slip is slip cast into a casting mold, the partly flocculated particles of silicon will interrupt an otherwise orderly packing of the particles of silicon and particles of yttrium. In this manner, the green density of the slip cast article is reduced and the article may be more easily nitrided.

Mangels, John A. (Flat Rock, MI); Dickie, Ray A. (Birmingham, MI)

1985-01-01

386

Clues from joint inversion of tsunami and geodetic data of the 2011 Tohoku-oki earthquake.  

PubMed

The 2011 Tohoku-oki (Mw 9.1) earthquake is so far the best-observed megathrust rupture, which allowed the collection of unprecedented offshore data. The joint inversion of tsunami waveforms (DART buoys, bottom pressure sensors, coastal wave gauges, and GPS-buoys) and static geodetic data (onshore GPS, seafloor displacements obtained by a GPS/acoustic combination technique), allows us to retrieve the slip distribution on a non-planar fault. We show that the inclusion of near-source data is necessary to image the details of slip pattern (maximum slip ~48?m, up to ~35?m close to the Japan trench), which generated the large and shallow seafloor coseismic deformations and the devastating inundation of the Japanese coast. We investigate the relation between the spatial distribution of previously inferred interseismic coupling and coseismic slip and we highlight the importance of seafloor geodetic measurements to constrain the interseismic coupling, which is one of the key-elements for long-term earthquake and tsunami hazard assessment. PMID:22545193

Romano, F; Piatanesi, A; Lorito, S; D'Agostino, N; Hirata, K; Atzori, S; Yamazaki, Y; Cocco, M

2012-01-01

387

Slip-line field theory and large-scale continental tectonics  

Microsoft Academic Search

A simple analogy is made between the tectonics of Asia and deformation in a rigidly indented rigid-plastic solid. India is analogous to the indenter and the great strike-slip faults correspond to slip lines. For various indentation geometries, the sense and linearity (or curvature) of strike-slip faults, convergence at the Burma arc and the existence of the Himalayan Burman Syntax, the

Paul Tapponnier; Peter Molnar

1976-01-01

388

The 2002 Denali Fault Earthquake, Alaska: A Large Magnitude, Slip-Partitioned Event  

Microsoft Academic Search

The MW (moment magnitude) 7.9 Denali fault earthquake on 3 November 2002 was associated with 340 kilometers of surface rupture and was the largest strike-slip earthquake in North America in almost 150 years. It illuminates earthquake mechanics and hazards of large strike-slip faults. It began with thrusting on the previously unrecognized Susitna Glacier fault, continued with right-slip on the Denali

Donna Eberhart-Phillips; Peter J. Haeussler; Jeffrey T. Freymueller; Arthur D. Frankel; Charles M. Rubin; Patricia Craw; Natalia A. Ratchkovski; Greg Anderson; Gary A. Carver; Anthony J. Crone; Timothy E. Dawson; Hilary Fletcher; Roger Hansen; Edwin L. Harp; Ruth A. Harris; David P. Hill; Sigrún Hreinsdóttir; Randall W. Jibson; Lucile M. Jones; Robert Kayen; David K. Keefer; Christopher F. Larsen; Seth C. Moran; Stephen F. Personius; George Plafker; Brian Sherrod; Kerry Sieh; Nicholas Sitar; Wesley K. Wallace

2003-01-01

389

Workers’ Experience of Slipping in U.S. Limited-Service Restaurants  

Microsoft Academic Search

The leading cause of injuries among restaurant workers is same-level falls, a significant proportion of which result from slipping. This study examines the experience of limited-service restaurant workers with slipping, their use of slip-resistant shoes, and their floor-cleaning practices. A total of 475 workers from 36 limited-service restaurants in six U.S. states participated in a 12-week prospective cohort study on

Santosh K. Verma; Wen-Ruey Chang; Theodore K. Courtney; David A. Lombardi; Yueng-Hsiang Huang; Melanye J. Brennan; Murray A. Mittleman; Melissa J. Perry

2010-01-01

390

Double slotted socket spherical joint  

DOEpatents

A new class of spherical joints is disclosed. These spherical joints are capable of extremely large angular displacements (full cone angles in excess of 270.degree.), while exhibiting no singularities or dead spots in their range of motion. These joints can improve or simplify a wide range of mechanical devices.

Bieg, Lothar F. (Albuquerque, NM); Benavides, Gilbert L. (Albuquerque, NM)

2001-05-22

391

Phase 1 Program Joint Report  

NASA Technical Reports Server (NTRS)

This report consists of inputs from each of the Phase I Program Joint Working Groups. The Working Groups were tasked to describe the organizational structure and work processes that they used during the program, joint accomplishments, lessons learned, and applications to the International Space Station Program. This report is a top-level joint reference document that contains information of interest to both countries.

Nield, George C. (Editor); Vorobiev, Pavel Mikhailovich (Editor)

1999-01-01

392

The Challenges of Joint Attention  

Microsoft Academic Search

This paper discusses the concept of joint at- tention and the dierent skills underlying its development. We argue that joint attention is much more than gaze following or simul- taneous looking because it implies a shared intentional relation to the world. The current state-of-the-art in robotic and computational models of the dierent prerequisites of joint attention is discussed in relation

Frederic Kaplan; Verena V. Hafner

2004-01-01

393

Major strike-slip faulting along the tectonic boundary between East and West Antarctica: implications for early Gondwana break-up and Jurassic granitic magma emplacement  

NASA Astrophysics Data System (ADS)

The fragmentation of the Gondwana supercontinent began with continental rifting between the Weddell Sea region of Antarctica and South Africa during the Jurassic. This initial Jurassic phase of continental rifting is critical for understanding the process that initiated supercontinent breakup and dispersal, including the role of mantle plumes and major intracrustal tectonic structures. However, due to the remote location and blanketing ice sheets, the tectonic and magmatic evolution of the Weddell Sea Sector of Antarctica has remained relatively poorly understood. Our recent aeromagnetic and airborne gravity investigations have revealed the inland extent of the Weddell Sea Rift system beneath the West Antarctic Ice Sheet, and indicate the presence of a major left-lateral strike slip fault system separating the Ellsworth Whitmore block (a possible exotic microcontinent derived from the Natal Embayment, or the Shackleton Range region of East Antarctica) from East Antarctica (Jordan et al., 2013 Tectonophysics). In this study we use GPlates plate-tectonic reconstruction software to start evaluating the influence of strike-slip faulting between East and West Antarctica on Gondwana breakup models. Specifically, we investigate the possibility of poly-phase motion along the fault system and explore scenarios involving more diffuse strike slip faulting extending into the interior of East Antarctica in the hinterland of the Transantarctic Mountains. Our preliminary models suggest that there may be a link between the prominent step in the flank of the later Cretaceous-Cenozoic West Antarctic Rift System (at the southern end of Ellsworth-Whitmore Block) and the earlier Jurassic Weddell Sea rift system. Additionally, we present preliminary joint 3D magnetic and gravity models to investigate the crustal architecture of the proposed strike-slip fault system and assess its influence on the emplacement of voluminous Jurassic granitic magmatism along the boundary of the Ellsworth-Whitmore block.

Jordan, T. A.; Ferraccioli, F.; Anderson, L.; Ross, N.; Corr, H.; Leat, P. T.; Bingham, R.; Rippin, D. M.; Le Brocq, A. M.; Siegert, M. J.

2013-12-01

394

Emergency repair of extensor tendon central slip defects with Oberlin's bypass technique: Feasibility and results in 4 cases with more than 5years of follow-up.  

PubMed

Treatment of soft tissues defects in the central slip of the extensor tendon at the proximal interphalangeal (PIP) joint is challenging because of the potential for stiffness and boutonniere deformity. The bypass procedure proposed by Oberlin for secondary injuries is an attractive solution. This salvage procedure uses a free tendon graft (palmaris longus) that is intercalated between the extensor indicis proprius muscle and the base of the middle phalanx. This study reports on the first cases of acute central slip defect treated in an emergency setting. Four patients with an average age of 37years (range 11-69) were treated by the same surgeon using the bypass procedure. Clinical evaluations consisted of measuring the active range of motion in the PIP joint, QuickDASH, Total Active Motion (TAM) and strength with a Jamar(®) dynamometer. All patients had reintegrated their injured finger into their body image within three months. At the last follow-up, the average active mobility was 0-5-76.5°. The functional outcomes were similar at nine months, with an average mobility of 0-13-72°. The two patients who were working at the time of injury were able to return to work in the third month. Various procedures such as tendon plasty, transfer or graft have been described in the literature for posttraumatic chronic boutonnière deformity. In cases where significant defects exist not only in the tendon, but the bone and skin, the bypass procedure is an effective approach to achieving satisfactory functional outcomes. PMID:24981577

Feuvrier, D; Loisel, F; Pauchot, J; Obert, L

2014-10-01

395

Influence of fault connectivity on slip rates in southern California: Potential impact on discrepancies between geodetic derived and geologic slip rates  

NASA Astrophysics Data System (ADS)

the San Bernardino strand of the San Andreas fault (SAF) and across the eastern California shear zone (ECSZ), geologic slip rates differ from those inverted from geodetic measurements, which may partly be due to inaccurate fault connectivity within geodetic models. We employ three-dimensional models that are mechanically compatible with long-term plate motion to simulate both fault slip rates and interseismic surface deformation. We compare results from fault networks that follow mapped geologic traces and resemble those used in block model inversions, which connect the San Jacinto fault to the SAF near Cajon Pass and connect distinct faults within the ECSZ. The connection of the SAF with the San Jacinto fault decreases strike-slip rates along the SAF by up to 10% and increases strike-slip rates along the San Jacinto fault by up to 16%; however, slip rate changes are still within the large geologic ranges along the SAF. The insensitivity of interseismic surface velocities near Cajon Pass to fault connection suggests that inverse models may utilize both an incorrect fault geometry and slip rate and still provide an excellent fit to interseismic geodetic data. Similarly, connection of faults within the ECSZ produces 36% greater cumulative strike-slip rates but less than 17% increase in interseismic velocity. When using overconnected models to invert GPS for slip rates, the reduced off-fault deformation within the models can lead to overprediction of slip rates. While the nature of fault intersections at depth remains enigmatic, fault geometries should be chosen with caution in crustal deformation models.

Herbert, Justin W.; Cooke, Michele L.; Marshall, Scott T.

2014-03-01

396

Slip-related muscle activation patterns in the stance leg during walking.  

PubMed

Falls precipitated by slipping are a serious public health concern especially in the elderly. Muscular responses generated during slipping have not been investigated during gait on contaminated floors. This study compared slip-related muscular responses (reactive and proactive) in young and older adults and examined if characteristics of muscular activation patterns during normal gait impact slip severity on contaminated floors. Electromyographic recordings were made from the major shank and thigh muscles in the stance leg of 11 young and nine older adults. Three experimental conditions were included: (1) known dry floors (baseline), (2) unexpected contaminated floor, (3) alert dry (subjects uncertain of the floor's contaminant condition). Muscular responses to unexpected slips, similar in both age groups, included the activation of the Medial Hamstring (approximately 175 ms) followed by the onset of the Vastus Lateralis (approximately 240 ms). The power and duration of responses were scaled to slip severity. The Vastus Lateralis latency was delayed in severe slips. When experiencing a severe slip, young adults demonstrated a longer, more powerful response compared to older adults. Subjects who normally walk with greater ankle muscle co-contraction were predisposed to experience less severe slips when encountering an unexpected slippery floor. Finally, anticipation of a slippery surface resulted in more powerful muscular activity and muscle co-contraction at the ankle and knee compared to baseline gait, as well as earlier onsets and longer durations in the posterior muscles' activation. These findings may provide a greater understanding of the higher incidence of falls in the elderly. PMID:16876417

Chambers, April J; Cham, Rakié

2007-04-01

397

Strength of stick-slip and creeping subduction megathrusts from heat flow observations.  

PubMed

Subduction faults, called megathrusts, can generate large and hazardous earthquakes. The mode of slip and seismicity of a megathrust is controlled by the structural complexity of the fault zone. However, the relative strength of a megathrust based on the mode of slip is far from clear. The fault strength affects surface heat flow by frictional heating during slip. We model heat-flow data for a number of subduction zones to determine the fault strength. We find that smooth megathrusts that produce great earthquakes tend to be weaker and therefore dissipate less heat than geometrically rough megathrusts that slip mainly by creeping. PMID:25170149

Gao, Xiang; Wang, Kelin

2014-08-29

398

Evidence for 115 kilometers of right slip on the san gregorio-hosgri fault trend.  

PubMed

The San Gregorio-Hosgri fault trend is a component of the San Andreas fault system on which there may have been about 115 kilometers of post-early Miocene right-lateral strike slip. If so, right slip on the San Andreas and San Gregorio-Hosgri faults accounts for most of the movement between the Pacific and North American plates since mid-Miocene time. Furthermore, the magnitude of right slip on a Paleogene proto-San Andreas fault inferred from the present distribution of granitic basement is reduced considerably when Neogene-Recent San Gregorio-Hosgri right slip is taken into account. PMID:17812950

Graham, S A; Dickinson, W R

1978-01-13

399

Fault zone connectivity: slip rates on faults in the san francisco bay area, california.  

PubMed

The slip rate of a fault segment is related to the length of the fault zone of which it is part. In turn, the slip rate of a fault zone is related to its connectivity with adjoining or contiguous fault zones. The observed variation in slip rate on fault segments in the San Francisco Bay area in California is consistent with connectivity between the Hayward, Calaveras, and San Andreas fault zones. Slip rates on the southern Hayward fault taper northward from a maximum of more than 10 millimeters per year and are sensitive to the active length of the Maacama fault. PMID:17835127

Bilham, R; Bodin, P

1992-10-01

400

Mechanical Models of Coontinental Plate BoundariesL Fault Slip Rates and Interseismic Stress Rotation Rates.  

E-print Network

??We first describe the methodology for a two-dimensional, elastic deformable microplate modeling approach for continental plate boundaries. Deformable microplate models combine discrete slip on microplate… (more)

Langstaff, Meredith Avery

2014-01-01

401

The 2002 Denali fault earthquake, Alaska: a large magnitude, slip-partitioned event.  

PubMed

The MW (moment magnitude) 7.9 Denali fault earthquake on 3 November 2002 was associated with 340 kilometers of surface rupture and was the largest strike-slip earthquake in North America in almost 150 years. It illuminates earthquake mechanics and hazards of large strike-slip faults. It began with thrusting on the previously unrecognized Susitna Glacier fault, continued with right-slip on the Denali fault, then took a right step and continued with right-slip on the Totschunda fault. There is good correlation between geologically observed and geophysically inferred moment release. The earthquake produced unusually strong distal effects in the rupture propagation direction, including triggered seismicity. PMID:12750512

Eberhart-Phillips, Donna; Haeussler, Peter J; Freymueller, Jeffrey T; Frankel, Arthur D; Rubin, Charles M; Craw, Patricia; Ratchkovski, Natalia A; Anderson, Greg; Carver, Gary A; Crone, Anthony J; Dawson, Timothy E; Fletcher, Hilary; Hansen, Roger; Harp, Edwin L; Harris, Ruth A; Hill, David P; Hreinsdóttir, Sigrun; Jibson, Randall W; Jones, Lucile M; Kayen, Robert; Keefer, David K; Larsen, Christopher F; Moran, Seth C; Personius, Stephen F; Plafker, George; Sherrod, Brian; Sieh, Kerry; Sitar, Nicholas; Wallace, Wesley K

2003-05-16

402

Effects of foot placement, hand positioning, age and climbing biodynamics on ladder slip outcomes.  

PubMed

Ladder falls frequently cause severe injuries; yet the factors that influence ladder slips/falls are not well understood. This study aimed to quantify (1) the effects of restricted foot placement, hand positioning, climbing direction and age on slip outcomes, and (2) differences in climbing styles leading to slips versus styles leading to non-slips. Thirty-two occupational ladder users from three age groups (18-24, 25-44 and 45-64 years) were unexpectedly slipped climbing a vertical ladder, while being assigned to different foot placement conditions (unrestricted vs. restricted toe clearance) and different hand positions (rails vs. rungs). Constraining foot placement increased the climber's likelihood of slipping (p < 0.01), while younger and older participants slipped more than the middle-aged group (p < 0.01). Longer double stance time, dissimilar and more variable foot and body positioning were found in styles leading to a slip. Maintaining sufficient toe clearance and targeting ladder safety training to younger and older workers may reduce ladder falls. Practitioner Summary: Ladder falls frequently cause severe occupational fall injuries. This study aims to identify safer ladder climbing techniques and individuals at risk of falling. The results suggest that ladders with unrestricted toe clearance and ladder climbing training programmes, particularly for younger and older workers, may reduce ladder slipping risk. PMID:25116116

Pliner, Erika M; Campbell-Kyureghyan, Naira H; Beschorner, Kurt E

2014-11-01

403

Mirror-like slip surfaces in dolostone: natural and experimental constraints on a potential seismic marker  

NASA Astrophysics Data System (ADS)

The lack of clear geological markers of seismic faulting represents a major limitation in our current comprehension of earthquake physics. At present pseudotachylytes (i.e. friction-induced melts) are the only unambiguously identified indicator of ancient seismicity in exhumed fault zones, but pseudotachylytes are not found in many rock types, including carbonates. We report the occurrence of small-displacement, mirror-like slip surfaces from a fault zone cutting dolostones. A combination of field observations and rotary shear friction experiments suggests that such slip surfaces: 1) are formed only at seismic slip rates, and 2) could potentially be used to estimate power dissipation during individual slip events. The Foiana Line (FL) is a major NNE-SSW-trending sinistral transpressive fault in the Italian Southern Alps. The outcropping fault zone consists of a <300 m wide zone of heavily fractured ("pulverized") dolostones cut by a network of mirror-like slip surfaces. The slip surfaces have displacements ranging between 0.04 m and 0.5 m and their mirror-like appearance indicates that the wavelength of surface roughness is <1 ?m. The slip surfaces have mainly dip-slip reverse kinematics and were exhumed from ~2 km depth. Resolved normal stress on the slip surfaces is estimated in the range 30-50 MPa. To understand how the mirror-like slip surfaces may have developed, slow- to high-velocity rotary-shear experiments using SHIVA (INGV, Rome) were performed on 3 mm thick layers of dolomite gouge (grain size <250 ?m) collected from the FL. Tests were conducted using a purpose-built gouge sample holder at slip rates of 0.0001-1.13 m/s, normal stresses up to 26 MPa and displacements in the range 0.02-3.5 m. At seismic slip rates of 1.13 m/s the dolomite gouge shows a dramatic reduction of the friction coefficient (?) from a peak value of ~0.7 to a steady-state value of ~0.25. The gouge starts to weaken above a threshold velocity in the range 0.19-0.49 m/s following a transient phase of strengthening. During the tests the instantaneous power density (shear stress*slip rate) dissipated on the sample reaches values of 6-10 MW/m2 over distances of 0.02-1 m, comparable to those of natural earthquakes. At 26 MPa normal stress a mirror-like slip surface is formed after only 0.03 m of slip. At intermediate slip rates (0.113 m/s) only moderate reductions in ? are observed. Instantaneous power density is ~1 MW/m2 and the mirror-like slip surface starts to develop after 0.1 m of slip. At sub-seismic slip rates (0.0001-0.0013 m/s) ? remains ~0.7, instantaneous power density is ~0.02 MW/m2, and no mirror-like slip surface develops. Microstructural observations suggest that the natural and experimental slip zones are comparable: both have a compacted layer up to 20 ?m thick immediately below the mirror-like slip surface in which deformation is strongly localized. The layer consists of partially-welded dolomite clasts 0.1-10 ?m in size. In the experimental samples, chemical analyses recognized small (<100 ?m long), discontinuous patches of periclase and Mg-calcite nanoparticles formed by dolomite decomposition. Field, experimental and microstructural data suggest that mirror-like slip surfaces in dolostone develop at seismic conditions, when instantaneous power density is of the order of 1-10 MW/m2.

Fondriest, M.; Smith, S. A.; Di Toro, G.; Nielsen, S. B.

2012-12-01

404

Joint hypermobility syndrome pain.  

PubMed

Joint hypermobility syndrome (JHS) was initially defined as the occurrence of musculoskeletal symptoms in the presence of joint laxity and hypermobility in otherwise healthy individuals. It is now perceived as a commonly overlooked, underdiagnosed, multifaceted, and multisystemic heritable disorder of connective tissue (HDCT), which shares many of the phenotypic features of other HDCTs such as Marfan syndrome and Ehlers-Danlos syndrome. Whereas the additional flexibility can confer benefits in terms of mobility and agility, adverse effects of tissue laxity and fragility can give rise to clinical consequences that resonate far beyond the confines of the musculoskeletal system. There is hardly a clinical specialty to be found that is not touched in one way or another by JHS. Over the past decade, it has become evident that of all the complications that may arise in JHS, chronic pain is arguably the most menacing and difficult to treat. PMID:19889283

Grahame, Rodney

2009-12-01

405

Joint Venture Marketing  

Microsoft Academic Search

Joint venture marketing links a for profit organization with a non-profit organization for their mutual benefit. Since American Express launched its 1981 Statue of Liberty\\/Ellis Island campaign, the strategy has proliferated among all types of health care organizations, manufacturers and even financial and educational institutions. With the successes have come concerns about non-profits having to compromise their integrity, the elimination

Nora Ganin Barnes

1991-01-01

406

Jointly Poisson processes  

Microsoft Academic Search

What constitutes jointly Poisson processes remains an unresolved issue. This\\u000areport reviews the current state of the theory and indicates how the accepted\\u000abut unproven model equals that resulting from the small time-interval limit of\\u000ajointly Bernoulli processes. One intriguing consequence of these models is that\\u000ajointly Poisson processes can only be positively correlated as measured by the\\u000acorrelation coefficient

Don H. Johnson; Ilan N. Goodman

2009-01-01