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  1. Earthquake swarms on transform faults

    NASA Astrophysics Data System (ADS)

    Roland, Emily; McGuire, Jeffrey J.

    2009-09-01

    Swarm-like earthquake sequences are commonly observed in a diverse range of geological settings including volcanic and geothermal regions as well as along transform plate boundaries. They typically lack a clear mainshock, cover an unusually large spatial area relative to their total seismic moment release, and fail to decay in time according to standard aftershock scaling laws. Swarms often result from a clear driving phenomenon, such as a magma intrusion, but most lack the necessary geophysical data to constrain their driving process. To identify the mechanisms that cause swarms on strike-slip faults, we use relative earthquake locations to quantify the spatial and temporal characteristics of swarms along Southern California and East Pacific Rise transform faults. Swarms in these regions exhibit distinctive characteristics, including a relatively narrow range of hypocentral migration velocities, on the order of a kilometre per hour. This rate corresponds to the rupture propagation velocity of shallow creep transients that are sometimes observed geodetically in conjunction with swarms, and is significantly faster than the earthquake migration rates typically associated with fluid diffusion. The uniformity of migration rates and low effective stress drops observed here suggest that shallow aseismic creep transients are the primary process driving swarms on strike-slip faults. Moreover, the migration rates are consistent with laboratory values of the rate-state friction parameter b (0.01) as long as the Salton Trough faults fail under hydrostatic conditions.

  2. Origin and models of oceanic transform faults

    NASA Astrophysics Data System (ADS)

    Gerya, Taras

    2012-02-01

    Mid-ocean ridges sectioned by transform faults represent prominent surface expressions of plate tectonics. A fundamental problem of plate tectonics is how this pattern has formed and why it is maintained. Gross-scale geometry of mid-ocean ridges is often inherited from respective rifted margins. Indeed, transform faults seem to nucleate after the beginning of the oceanic spreading and can spontaneously form at a single straight ridge. Both analog and numerical models of transform faults were investigated since the 1970s. Two main groups of analog models were developed: thermomechanical (freezing wax) models with accreting and cooling plates and mechanical models with non-accreting lithosphere. Freezing wax models reproduced ridge-ridge transform faults, inactive fracture zones, rotating microplates, overlapping spreading centers and other features of oceanic ridges. However, these models often produced open spreading centers that are dissimilar to nature. Mechanical models, on the other hand, do not accrete the lithosphere and their results are thus only applicable for relatively small amount of spreading. Three main types of numerical models were investigated: models of stress and displacement distribution around transforms, models of their thermal structure and crustal growth, and models of nucleation and evolution of ridge-transform fault patterns. It was shown that a limited number of spreading modes can form: transform faults, microplates, overlapping spreading centers, zigzag ridges and oblique connecting spreading centers. However, the controversy exists whether these patterns always result from pre-existing ridge offsets or can also form spontaneously at a single straight ridge during millions of year of accretion. Therefore, two types of transform fault interpretation exist: plate fragmentation structures vs. plate accretion structures. Models of transform faults are yet relatively scarce and partly controversial. Consequently, a number of first order

  3. Do transform faults parallel plate motion?

    NASA Astrophysics Data System (ADS)

    Mishra, J. K.; Gordon, R. G.; Demets, C.; Argus, D.

    2009-12-01

    A central principle of plate tectonics is that relative plate motion is parallel to transform faults. Several workers have convincingly argued, however, that transform fault valleys widen with age due to horizontal thermal contraction of the lithosphere [Collette 1974; Roest et al 1986 ; Sandwell 1986]. If so, then the transform fault zone, which is the locus of active strike-slip faulting in a transform fault, may not be parallel to the direction of relative plate motion, but parallel to the relative velocity of the walls of the transform valley. Here we apply a recent model for horizontal contraction of oceanic lithosphere as a function of age [Kumar & Gordon 2009] to calculate this bias in transform azimuth as a function of offset, spreading rate, and ridge length, with slightly different formulations for crenelate and stepping mid-ocean ridge segments. The calculated bias increases with increasing length of ridge segments between transform faults and decreases with increasing offset of ridge segments along transform faults. We used the calculated bias to estimate corrections of azimuths of transform faults on eight plate boundaries from the MORVEL data set [DeMets, Argus, & Gordon, 2009]. The largest correction is 2.3 degrees, but the median correction is merely 0.2 degrees. We express the null hypothesis (no thermal contraction) and our hypothesis (thermal contraction as predicted by Kumar and Gordon [2009]), in terms of a parameter α, which is zero for no thermal contraction and 1 for predicted thermal contraction. When the results for the 8 plate pairs are combined, we find that α = 1.1 ± 0.7 (95% confidence limits), thus excluding the null hypothesis (no thermal contraction), but consistent with the hypothesis of horizontal thermal contraction.

  4. Sea-Floor Spreading and Transform Faults

    ERIC Educational Resources Information Center

    Armstrong, Ronald E.; And Others

    1978-01-01

    Presents the Crustal Evolution Education Project (CEEP) instructional module on Sea-Floor Spreading and Transform Faults. The module includes activities and materials required, procedures, summary questions, and extension ideas for teaching Sea-Floor Spreading. (SL)

  5. Do transform faults parallel plate motion?

    NASA Astrophysics Data System (ADS)

    Mishra, J. K.; Gordon, R. G.

    2008-12-01

    A central principle of plate tectonics is that relative plate motion is parallel to transform faults. Several workers have convincingly argued, however, that transform fault valleys widen with age due to horizontal thermal contraction of the lithosphere (Collette 1974; Roest et al 1986 ; Sandwell 1986). If so, then the transform fault zone, which is the locus of active strike-slip faulting in a transform fault, is not parallel to the direction of plate motion. It is also affected by the ridge-parallel contraction of the lithosphere and is biased by a predictable amount. Here we apply a recent model for horizontal contraction of oceanic lithosphere as a function of age (Kumar & Gordon 2008) to calculate this bias as a function of offset, spreading rate, and ridge length, with slightly different formulations for crenelate and stepping mid-ocean ridge segments. The bias causes right-slipping transform faults to be counter-clockwise of the true plate motion direction while left-slipping transform faults are clockwise of the true plate motion direction. The bias is larger for longer ridge segments, smaller offsets, and slower spreading. The bias ranges in magnitude from about 0.1 degree to 1.5 degrees for stepping boundaries and 0.2 degree to 3 degrees for crenelate boundaries. Application of the bias correction to NUVEL-1 transform fault azimuths about the Rodrigues, Juan Fernandez, Galapagos, and Bouvet triple junctions improves the closure of the triple junction in the first three cases but makes it slightly worse in the fourth case. Additional applications will be presented.

  6. Earthquake slip on oceanic transform faults.

    PubMed

    Abercrombie, R E; Ekström, G

    2001-03-01

    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

  7. Earthquake slip on oceanic transform faults.

    PubMed

    Abercrombie, R E; Ekström, G

    2001-03-01

    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.

  8. Thermal structure of oceanic transform faults

    USGS Publications Warehouse

    Behn, M.D.; Boettcher, M.S.; Hirth, G.

    2007-01-01

    We use three-dimensional finite element simulations to investigate the temperature structure beneath oceanic transform faults. We show that using a rheology that incorporates brittle weakening of the lithosphere generates a region of enhanced mantle upwelling and elevated temperatures along the transform; the warmest temperatures and thinnest lithosphere are predicted to be near the center of the transform. Previous studies predicted that the mantle beneath oceanic transform faults is anomalously cold relative to adjacent intraplate regions, with the thickest lithosphere located at the center of the transform. These earlier studies used simplified rheologic laws to simulate the behavior of the lithosphere and underlying asthenosphere. We show that the warmer thermal structure predicted by our calculations is directly attributed to the inclusion of a more realistic brittle rheology. This temperature structure is consistent with a wide range of observations from ridge-transform environments, including the depth of seismicity, geochemical anomalies along adjacent ridge segments, and the tendency for long transforms to break into small intratransform spreading centers during changes in plate motion. ?? 2007 Geological Society of America.

  9. Transformer fault diagnosis using continuous sparse autoencoder.

    PubMed

    Wang, Lukun; Zhao, Xiaoying; Pei, Jiangnan; Tang, Gongyou

    2016-01-01

    This paper proposes a novel continuous sparse autoencoder (CSAE) which can be used in unsupervised feature learning. The CSAE adds Gaussian stochastic unit into activation function to extract features of nonlinear data. In this paper, CSAE is applied to solve the problem of transformer fault recognition. Firstly, based on dissolved gas analysis method, IEC three ratios are calculated by the concentrations of dissolved gases. Then IEC three ratios data is normalized to reduce data singularity and improve training speed. Secondly, deep belief network is established by two layers of CSAE and one layer of back propagation (BP) network. Thirdly, CSAE is adopted to unsupervised training and getting features. Then BP network is used for supervised training and getting transformer fault. Finally, the experimental data from IEC TC 10 dataset aims to illustrate the effectiveness of the presented approach. Comparative experiments clearly show that CSAE can extract features from the original data, and achieve a superior correct differentiation rate on transformer fault diagnosis.

  10. Initiation of Ridges and Transform Faults

    NASA Astrophysics Data System (ADS)

    Nyst, M.; Thompson, G. A.; Parsons, T.

    2004-12-01

    No clear consensus has emerged to explain initiation of the strikingly regular pattern of ocean ridges and transform faults. The question is important on the continents also, because a less regular pattern of step-overs on faults such as the San Andreas influences the sources of earthquakes. We explore the question by finite element modeling and a study of observational data on ridges and transforms. We focus on the simplest case, where ridges and transforms seem to self-organize at new plate boundaries as soon as new oceanic (magmatic) crust forms. The South Atlantic supplies a clear example. Continental South America and Africa separated along an irregular break, whose general shape is still preserved in the Mid-Atlantic Ridge. In detail, however, the sea floor magnetic anomalies and satellite gravity show that traces of the ridges and transforms extend to the base of the continental slope, i.e. they formed quickly in the new oceanic crust. The Gulf of California provides another clear example and is notable because of its northward transition into the continental San Andreas fault system. In continental crust, dike segments connected by transform faults provide the clearest analogues of oceanic ridges and transforms. Remarkably, the ridge-transform pattern has been simulated by pulling the crust on molten wax [Oldenburg and Brune, JGR, 80, 1975] and also observed in the crust of a molten lava lake [Duffield, JGR, 77, 1972]. In neither of these models, however, do the spatial and temporal scales permit investigation of the dikes whose repeated emplacement and inflation builds layer 3 of the ocean crust. It is well established that, under a buoyant head of magma, dikes tend to fracture and intrude the crust in planes perpendicular to the least horizontal stress, and they relieve the stress difference as they inflate [e.g. Parsons and Thompson, Science, 253, 1991]. Dikes are commonly used as stress-direction indicators analogous to artificial hydraulic fractures

  11. Transform fault earthquakes in the North Atlantic: Source mechanisms and depth of faulting

    NASA Technical Reports Server (NTRS)

    Bergman, Eric A.; Solomon, Sean C.

    1987-01-01

    The centroid depths and source mechanisms of 12 large earthquakes on transform faults of the northern Mid-Atlantic Ridge were determined from an inversion of long-period body waveforms. The earthquakes occurred on the Gibbs, Oceanographer, Hayes, Kane, 15 deg 20 min, and Vema transforms. The depth extent of faulting during each earthquake was estimated from the centroid depth and the fault width. The source mechanisms for all events in this study display the strike slip motion expected for transform fault earthquakes; slip vector azimuths agree to 2 to 3 deg of the local strike of the zone of active faulting. The only anomalies in mechanism were for two earthquakes near the western end of the Vema transform which occurred on significantly nonvertical fault planes. Secondary faulting, occurring either precursory to or near the end of the main episode of strike-slip rupture, was observed for 5 of the 12 earthquakes. For three events the secondary faulting was characterized by reverse motion on fault planes striking oblique to the trend of the transform. In all three cases, the site of secondary reverse faulting is near a compression jog in the current trace of the active transform fault zone. No evidence was found to support the conclusions of Engeln, Wiens, and Stein that oceanic transform faults in general are either hotter than expected from current thermal models or weaker than normal oceanic lithosphere.

  12. Transform fault earthquakes in the North Atlantic - Source mechanisms and depth of faulting

    NASA Technical Reports Server (NTRS)

    Bergman, Eric A.; Solomon, Sean C.

    1988-01-01

    The centroid depths and source mechanisms of 12 large earthquakes on transform faults of the northern Mid-Atlantic Ridge were determined from an inversion of long-period body waveforms. The earthquakes occurred on the Gibbs, Oceanographer, Hayes, Kane, 15 deg 20 min, and Vema transforms. The depth extent of faulting during each earthquake was estimated from the centroid depth and the fault width. The source mechanisms for all events in this study display the strike slip motion expected for transform fault earthquakes; slip vector azimuths agree to 2 to 3 deg of the local strike of the zone of active faulting. The only anomalies in mechanism were for two earthquakes near the western end of the Vema transform which occurred on significantly nonvertical fault planes. Secondary faulting, occurring either precursory to or near the end of the main episode of strike-slip rupture, was observed for 5 of the 12 earthquakes. For three events the secondary faulting was characterized by reverse motion on fault planes striking oblique to the trend of the transform. In all three cases, the site of secondary reverse faulting is near a compression jog in the current trace of the active transform fault zone. No evidence was found to support the conclusions of Engeln, Wiens, and Stein that oceanic transform faults in general are either hotter than expected from current thermal models or weaker than normal oceanic lithosphere.

  13. Dynamical instability produces transform faults at mid-ocean ridges.

    PubMed

    Gerya, Taras

    2010-08-27

    Transform faults at mid-ocean ridges--one of the most striking, yet enigmatic features of terrestrial plate tectonics--are considered to be the inherited product of preexisting fault structures. Ridge offsets along these faults therefore should remain constant with time. Here, numerical models suggest that transform faults are actively developing and result from dynamical instability of constructive plate boundaries, irrespective of previous structure. Boundary instability from asymmetric plate growth can spontaneously start in alternate directions along successive ridge sections; the resultant curved ridges become transform faults within a few million years. Fracture-related rheological weakening stabilizes ridge-parallel detachment faults. Offsets along the transform faults change continuously with time by asymmetric plate growth and discontinuously by ridge jumps. PMID:20798313

  14. Dynamical instability produces transform faults at mid-ocean ridges.

    PubMed

    Gerya, Taras

    2010-08-27

    Transform faults at mid-ocean ridges--one of the most striking, yet enigmatic features of terrestrial plate tectonics--are considered to be the inherited product of preexisting fault structures. Ridge offsets along these faults therefore should remain constant with time. Here, numerical models suggest that transform faults are actively developing and result from dynamical instability of constructive plate boundaries, irrespective of previous structure. Boundary instability from asymmetric plate growth can spontaneously start in alternate directions along successive ridge sections; the resultant curved ridges become transform faults within a few million years. Fracture-related rheological weakening stabilizes ridge-parallel detachment faults. Offsets along the transform faults change continuously with time by asymmetric plate growth and discontinuously by ridge jumps.

  15. A dynamic integrated fault diagnosis method for power transformers.

    PubMed

    Gao, Wensheng; Bai, Cuifen; Liu, Tong

    2015-01-01

    In order to diagnose transformer fault efficiently and accurately, a dynamic integrated fault diagnosis method based on Bayesian network is proposed in this paper. First, an integrated fault diagnosis model is established based on the causal relationship among abnormal working conditions, failure modes, and failure symptoms of transformers, aimed at obtaining the most possible failure mode. And then considering the evidence input into the diagnosis model is gradually acquired and the fault diagnosis process in reality is multistep, a dynamic fault diagnosis mechanism is proposed based on the integrated fault diagnosis model. Different from the existing one-step diagnosis mechanism, it includes a multistep evidence-selection process, which gives the most effective diagnostic test to be performed in next step. Therefore, it can reduce unnecessary diagnostic tests and improve the accuracy and efficiency of diagnosis. Finally, the dynamic integrated fault diagnosis method is applied to actual cases, and the validity of this method is verified.

  16. A Dynamic Integrated Fault Diagnosis Method for Power Transformers

    PubMed Central

    Gao, Wensheng; Liu, Tong

    2015-01-01

    In order to diagnose transformer fault efficiently and accurately, a dynamic integrated fault diagnosis method based on Bayesian network is proposed in this paper. First, an integrated fault diagnosis model is established based on the causal relationship among abnormal working conditions, failure modes, and failure symptoms of transformers, aimed at obtaining the most possible failure mode. And then considering the evidence input into the diagnosis model is gradually acquired and the fault diagnosis process in reality is multistep, a dynamic fault diagnosis mechanism is proposed based on the integrated fault diagnosis model. Different from the existing one-step diagnosis mechanism, it includes a multistep evidence-selection process, which gives the most effective diagnostic test to be performed in next step. Therefore, it can reduce unnecessary diagnostic tests and improve the accuracy and efficiency of diagnosis. Finally, the dynamic integrated fault diagnosis method is applied to actual cases, and the validity of this method is verified. PMID:25685841

  17. An artificial neural network approach to transformer fault diagnosis

    SciTech Connect

    Zhang, Y.; Ding, X.; Liu, Y.; Griffin, P.J.

    1996-10-01

    This paper presents an artificial neural network (ANN) approach to diagnose and detect faults in oil-filled power transformers based on dissolved gas-in-oil analysis. A two-step ANN method is used to detect faults with or without cellulose involved. Good diagnosis accuracy is obtained with the proposed approach.

  18. Oceanic transform faults: how and why do they form? (Invited)

    NASA Astrophysics Data System (ADS)

    Gerya, T.

    2013-12-01

    Oceanic transform faults at mid-ocean ridges are often considered to be the direct product of plate breakup process (cf. review by Gerya, 2012). In contrast, recent 3D thermomechanical numerical models suggest that transform faults are plate growth structures, which develop gradually on a timescale of few millions years (Gerya, 2010, 2013a,b). Four subsequent stages are predicted for the transition from rifting to spreading (Gerya, 2013b): (1) crustal rifting, (2) multiple spreading centers nucleation and propagation, (3) proto-transform faults initiation and rotation and (4) mature ridge-transform spreading. Geometry of the mature ridge-transform system is governed by geometrical requirements for simultaneous accretion and displacement of new plate material within two offset spreading centers connected by a sustaining rheologically weak transform fault. According to these requirements, the characteristic spreading-parallel orientation of oceanic transform faults is the only thermomechanically consistent steady state orientation. Comparison of modeling results with the Woodlark Basin suggests that the development of this incipient spreading region (Taylor et al., 2009) closely matches numerical predictions (Gerya, 2013b). Model reproduces well characteristic 'rounded' contours of the spreading centers as well as the presence of a remnant of the broken continental crustal bridge observed in the Woodlark basin. Similarly to the model, the Moresby (proto)transform terminates in the oceanic rather than in the continental crust. Transform margins and truncated tip of one spreading center present in the model are documented in nature. In addition, numerical experiments suggest that transform faults can develop gradually at mature linear mid-ocean ridges as the result of dynamical instability (Gerya, 2010). Boundary instability from asymmetric plate growth can spontaneously start in alternate directions along successive ridge sections; the resultant curved ridges become

  19. Spreading rate dependence of gravity anomalies along oceanic transform faults.

    PubMed

    Gregg, Patricia M; Lin, Jian; Behn, Mark D; Montési, Laurent G J

    2007-07-12

    Mid-ocean ridge morphology and crustal accretion are known to depend on the spreading rate of the ridge. Slow-spreading mid-ocean-ridge segments exhibit significant crustal thinning towards transform and non-transform offsets, which is thought to arise from a three-dimensional process of buoyant mantle upwelling and melt migration focused beneath the centres of ridge segments. In contrast, fast-spreading mid-ocean ridges are characterized by smaller, segment-scale variations in crustal thickness, which reflect more uniform mantle upwelling beneath the ridge axis. Here we present a systematic study of the residual mantle Bouguer gravity anomaly of 19 oceanic transform faults that reveals a strong correlation between gravity signature and spreading rate. Previous studies have shown that slow-slipping transform faults are marked by more positive gravity anomalies than their adjacent ridge segments, but our analysis reveals that intermediate and fast-slipping transform faults exhibit more negative gravity anomalies than their adjacent ridge segments. This finding indicates that there is a mass deficit at intermediate- and fast-slipping transform faults, which could reflect increased rock porosity, serpentinization of mantle peridotite, and/or crustal thickening. The most negative anomalies correspond to topographic highs flanking the transform faults, rather than to transform troughs (where deformation is probably focused and porosity and alteration are expected to be greatest), indicating that crustal thickening could be an important contributor to the negative gravity anomalies observed. This finding in turn suggests that three-dimensional magma accretion may occur near intermediate- and fast-slipping transform faults. PMID:17625563

  20. Spreading rate dependence of gravity anomalies along oceanic transform faults.

    PubMed

    Gregg, Patricia M; Lin, Jian; Behn, Mark D; Montési, Laurent G J

    2007-07-12

    Mid-ocean ridge morphology and crustal accretion are known to depend on the spreading rate of the ridge. Slow-spreading mid-ocean-ridge segments exhibit significant crustal thinning towards transform and non-transform offsets, which is thought to arise from a three-dimensional process of buoyant mantle upwelling and melt migration focused beneath the centres of ridge segments. In contrast, fast-spreading mid-ocean ridges are characterized by smaller, segment-scale variations in crustal thickness, which reflect more uniform mantle upwelling beneath the ridge axis. Here we present a systematic study of the residual mantle Bouguer gravity anomaly of 19 oceanic transform faults that reveals a strong correlation between gravity signature and spreading rate. Previous studies have shown that slow-slipping transform faults are marked by more positive gravity anomalies than their adjacent ridge segments, but our analysis reveals that intermediate and fast-slipping transform faults exhibit more negative gravity anomalies than their adjacent ridge segments. This finding indicates that there is a mass deficit at intermediate- and fast-slipping transform faults, which could reflect increased rock porosity, serpentinization of mantle peridotite, and/or crustal thickening. The most negative anomalies correspond to topographic highs flanking the transform faults, rather than to transform troughs (where deformation is probably focused and porosity and alteration are expected to be greatest), indicating that crustal thickening could be an important contributor to the negative gravity anomalies observed. This finding in turn suggests that three-dimensional magma accretion may occur near intermediate- and fast-slipping transform faults.

  1. Seismicity at interactions of spreading centers and transform faults

    SciTech Connect

    Rowlett, H.

    1981-05-10

    Ocean-bottom seismographs were used in a microearthquake monitoring experiment at the eastern junction of the Oceanographer transform with the mid-Atlantic ridge at 35 /sup 0/N. Microearthquake activity at the junction occurred over a broad area (>7 km). These microearthquakes 'cut across' the corner between the transform and median valley and are associated with fault scarps that form the inner walls on the west and north sides of the median and transform valleys. At intersections of other major fracture zones (>100-km offset) and slow to moderate spreading centers microearthquake activity is also diffuse and cuts across the corner between the spreading center and transform fault. The narrow zone of decoupling (approx.1 km) observed between spreading center and transform boundaries by detailed geological studies at the Tamayo/East Pacific Rise and Vema/mid-Atlantic Ridge interactions suggest that the diffuse seismicity (20 to 30 km in width) does not reflect a diffuse plate boundary at the transition from rift to transform valley. Instead, the faulting probably reflects internal deformation of the corner by secondary faults off of the plate boundary.

  2. Microearthquake evidence for extension across the Kane transform fault

    SciTech Connect

    Wilcock, W.S.D. ); Purdy, G.M. ); Solomon, S.C. )

    1990-09-10

    The Kane is a slow slipping (25 mm/yr), large-offset (150 km) transform delineated by a pronounced transform valley. The experiment site lies in the eastern half of the transform, 40 km west of the eastern ridge-transform intersection, in a region of marked transform-parallel topography. Hypocentral parameters were determined for 86 earthquakes. To the southeast activity may be associated with the inside corner of the ridge transform intersection, while to the north about 20 events occurred in 7-m.y.-old crust in a region of ridge-parallel bathymetry. Six focal mechanisms were obtained from P wave first motions for events within the transform valley. The best constrained solutions, for four earthquakes within the network, show normal faulting on fault planes subparallel to the trend of the transform. All the mechanisms indicate a tension axis perpendicular to the trend of the transform. These results together with a significant historical record of large earthquakes near the experiment site lead the authors to conclude that the principal transform displacement zone was inactive during the experiment and that the activity they recorded is the result of extension in the adjacent lithosphere. The observed focal mechanisms and the inference that the axis of least compressive stress is approximately perpendicular to the transform provide direct evidence that the transform fault is mechanically weak relative to the surrounding lithosphere. Potential sources of extension across the transform include thermal stress in the young oceanic lithosphere, topographic loading, a small component of plate divergence normal to the transform, and northward motion of the asthenosphere relative to the surface plate.

  3. Ridge transform fault spreading pattern in freezing wax.

    PubMed

    Oldenburg, D W; Brune, J N

    1972-10-20

    A laboratory experiment shows that ridge-ridge transform faults, inactive fracture zones, and other features characteristic of spreading oceanic ridges can be produced in a variety of paraffins. Although the resultant pattern depends upon the temperature of the wax and the ratio of spreading rate to surface cooling, the characteristic orthogonal ridge transform fault system is a preferred mode of separation. Symmetric spreading occurs under conditions of no tensile strength across the ridge, and the stability of transform faults is a consequence of their lack of shear strength. The experiment also shows that properties characteristic of oceanic ridges occur under conditions of passive convection where upwelling of material at the ridge crest is a result only of hydrostatic forces in the fluid; that is, the plate separation is caused not by large convective forces beneath the ridge but rather by tensile forces in the plate. PMID:17735477

  4. Battery Fault Detection with Saturating Transformers

    NASA Technical Reports Server (NTRS)

    Davies, Francis J. (Inventor); Graika, Jason R. (Inventor)

    2013-01-01

    A battery monitoring system utilizes a plurality of transformers interconnected with a battery having a plurality of battery cells. Windings of the transformers are driven with an excitation waveform whereupon signals are responsively detected, which indicate a health of the battery. In one embodiment, excitation windings and sense windings are separately provided for the plurality of transformers such that the excitation waveform is applied to the excitation windings and the signals are detected on the sense windings. In one embodiment, the number of sense windings and/or excitation windings is varied to permit location of underperforming battery cells utilizing a peak voltage detector.

  5. Ductile Faults Control Seismogenic Movement on Oceanic Transforms

    NASA Astrophysics Data System (ADS)

    Lister, G. S.; Tkalcic, H.; Forster, M. A.; McClusky, S.

    2014-12-01

    Structural Geology is about 3D geometry and the symphony of kinematically-coordinated movement. In this case we discuss patterns of violent relative displacement inferred from focal plane data for earthquakes. Systematic stereographic analysis of centroid moment tensor data often shows well-defined orientation groups in scatterplots of fault plane normals and associated slip line vectors. These allow important geodynamic inferences, e.g., we can show that ductile faults control the geometry of oceanic transforms, and that normal fault earthquakes on spreading ridges are usually skewed with respect to adjacent transform faults. To explain this asymmetry requires finite rock strength, but it also means that it is not brittle failure that controls the orientation of oceanic transforms. This asymmetry also requires formation of tilt block geometries reminiscent of Basin-and-Range-style continental extension, systematic offset of earthquake hypocentres from the spreading ridge, and a general complexity in magma-fault interactions that is far beyond what might be expected if ocean-floor spreading is the result of dilating tension-mode fractures in dyke swarms. The role of ductile faulting should be given special mention because mostly it is argued that brittle faults are responsible for earthquakes. Yet many other examples of ductile faults in operation can be inferred, e.g., ductile faults associated with slab drop-off, where slab boudinage leads to extensional ductile faults and seismic activity driven by the pulling away of a relict slab, e.g., beneath the Hindu Kush. Another example might be found by close examination of the tectonic significance of the lowermost of the double (or paired) seismic zones such as can be seen in cross-sections of the subducting slab beneath Japan. The lowermost of the paired seismic zones may mark the locus of aseismic ductile shears or detachments formed by slumping of gigantic sheets of rock attempting to slide down the face of

  6. Extreme mantle uplift and exhumation along a transpressive transform fault

    NASA Astrophysics Data System (ADS)

    Maia, Marcia; Sichel, Susanna; Briais, Anne; Brunelli, Daniele; Ligi, Marco; Ferreira, Nicolas; Campos, Thomas; Mougel, Bérengère; Brehme, Isa; Hémond, Christophe; Motoki, Akihisa; Moura, Denise; Scalabrin, Carla; Pessanha, Ivo; Alves, Eliane; Ayres, Arthur; Oliveira, Pedro

    2016-08-01

    Mantle exhumation at slow-spreading ridges is favoured by extensional tectonics through low-angle detachment faults, and, along transforms, by transtension due to changes in ridge/transform geometry. Less common, exhumation by compressive stresses has been proposed for the large-offset transforms of the equatorial Atlantic. Here we show, using high-resolution bathymetry, seismic and gravity data, that the northern transform fault of the St Paul system has been controlled by compressive deformation since ~10 million years ago. The long-lived transpression resulted from ridge overlap due to the propagation of the northern Mid-Atlantic Ridge segment into the transform domain, which induced the migration and segmentation of the transform fault creating restraining stepovers. An anticlockwise change in plate motion at ~11 million years ago initially favoured extension in the left-stepping transform, triggering the formation of a transverse ridge, later uplifted through transpression, forming the St Peter and St Paul islets. Enhanced melt supply at the ridge axis due to the nearby Sierra Leone thermo chemical anomaly is responsible for the robust response of the northern Mid-Atlantic Ridge segment to the kinematic change. The long-lived process at the origin of the compressive stresses is directly linked to the nature of the underlying mantle and not to a change in the far-field stress regime.

  7. Seismicity of the Quebrada, Discovery, and Gofar Transform Faults

    NASA Astrophysics Data System (ADS)

    McGuire, J. J.; Collins, J. A.; Roland, E. C.; Behn, M. D.

    2009-12-01

    The Quebrada, Discovery, and Gofar transform faults exhibit many of the primary features of oceanic transform seismicity including abundant earthquake swarms and a significant contrast in seismic coupling between Gofar and Discovery (90% seismic) and Quebrada (>90% aseismic). Additionally, the Gofar and Discovery faults have a relatively regular seismic cycle with their largest earthquakes repeating roughly every five years. Using a network of 38 ocean bottom seismometers, we monitored the seismicity on these three faults for calendar year 2008. We detected over 100,000 earthquakes between the three faults ranging from magnitude 0.5 to 6.0. The earthquakes were located using P and S-wave arrival time picks and a 1-d velocity model appropriate for oceanic crust. Our array covered the 90 km long, westernmost segment of the Gofar fault. The large earthquakes corresponding to the end of this faults' most recent seismic cycle propagated from east to west along strike and our dataset captured the final ruptures in this cycle including a Mw 6.0 event on September 18, 2008 that was recorded on scale by strong-motion accelerometers. The western Gofar segment is a highly localized plate boundary with perhaps only a single active fault, but it is divided along-strike into 4 distinct seismicity zones. The easternmost region last ruptured in August 2007 and we found it to have a relatively low level of microseismicity in 2008. To the west of this area is a ~10km long region that has likely been a barrier to rupture propagation in the last 4 seismic cycles. This barrier region had by far the highest rates of microseismicity during the first nine months of 2008 and had a large swarm in early September. The seismicity-rate in the barrier region was greatly reduced immediately after the September 18th Mw 6.0 event. The ~20 km long segment west of the barrier ruptured in the September 18th 2008 earthquake and shows a clear Omori-like aftershock sequence. The westernmost ~20 km of

  8. Syn-collisional transform faulting of the Tan-Lu fault zone, East China

    NASA Astrophysics Data System (ADS)

    Zhu, Guang; Liu, Guo Sheng; Niu, Man Lan; Xie, Cheng Long; Wang, Yong Sheng; Xiang, Biwei

    2009-02-01

    Origin of the continental-scale Tan-Lu fault zone (TLFZ), East China, remains controversial. About 550 km sinistral offset of the Dabie orogenic belt (DOB) and Sulu orogenic belt (SOB) is shown along the NE-NNE-striking TLFZ. Syn-collisional, sinistral ductile shear belts in the TLFZ have been identified. Thirteen phengite bulk separates from the mylonites were dated by the 40Ar/39Ar method. They gave cooling ages of the 198-181 Ma for the shear belts along the eastern margin of the DOB and 221-210 Ma from the western margin of the SOB. Distribution of the foreland basin deposits suggests that sinistral offset of the DOB and SOB by the TLFZ took place prior to deposition of the Upper Triassic strata. The marginal structures around the DOB and SOB support syn-collisional faulting, and indicate anticlockwise rotation of the DOB during the displacement. The folding and thrust faulting related to crustal subduction, coeval with the Tan-Lu faulting, is older than the foreland basin deposition related to the orogenic exhumation. Several lines of evidence demonstrate that the TLFZ was developed as a syn-collisional transform fault during latest Middle to earliest Late Triassic time when the DOB and SOB experienced crustal subduction of the South China Block (SCB). Eastward increase of the crustal subduction rates is believed to be responsible for the sinistral transform faulting.

  9. Earthquake Swarms and Aseismic Slip on Transform Faults (Invited)

    NASA Astrophysics Data System (ADS)

    Roland, E. C.; McGuire, J. J.; Collins, J. A.

    2009-12-01

    Swarms of ordinary earthquakes are common in environments where slow aseismic slip events are observed, such as strike-slip faults in the Salton Trough and oceanic transform faults. Although in some tectonic settings, the driving mechanisms that cause seismic swarms are well understood (i.e. magma intrusion in regions of volcanism), oceanic transform boundaries currently lack the geophysical data to constrain a distinct driving process. To identify the mechanisms that cause earthquake swarms on strike-slip faults, we use relative earthquake locations to quantify the spatial and temporal characteristics of swarms along Southern California and East Pacific Rise transforms. Swarms in these regions exhibit distinctive characteristics, including a relatively narrow range of hypocentral migration velocities, on the order of a kilometer per hour. This rate corresponds to the rupture propagation velocity of shallow creep transients that are sometimes observed geodetically in conjunction with swarms, and is significantly faster than the earthquake migration rates typically associated with fluid diffusion. Each of the swarms we examine also covers a large spatial area relative to its total seismic moment release and fails to decay in time according to standard aftershock scaling laws. Moreover, assuming the Salton Trough faults fail under hydrostatic conditions, the observed migration rate is consistent with laboratory values of the rate-state friction parameter b (0.01). Additionally, we present the first characterization of an oceanic transform fault swarm using data from a local ocean bottom seismometer array. The December 2008 Gofar Transform swarm lasted ~2 days and had at least 12 Mw>4.0 earthquakes. Using the local OBS data, we have detected and located over 5000 microearthquakes that occurred during this episode. This swarm nucleated close to the ridge-transform intersection and rapidly propagated ~10 km towards the center of the transform. The propagation rate (~0

  10. Intraplate termination of transform faulting within the Antarctic continent

    NASA Astrophysics Data System (ADS)

    Storti, F.; Salvini, F.; Rossetti, F.; Phipps Morgan, J.

    2007-08-01

    The sector of Antarctica facing Australia east of 139 °E is characterized by the abundance of exceptionally long oceanic fracture zones that are collinear to post-rift right-lateral strike-slip fault systems developed at the northeastern edge of the Antarctic continent. High-resolution reflection seismic profiles indicate recent strike-slip activity at the southeastern edge of the Balleny Fracture Zone, similar to what is observed onshore in North Victoria Land. The architecture, kinematics, and timing of this intraplate deformation at the northeastern edge of Antarctica cannot be reconciled with typical plate tectonic kinematics, in particular, with a classical divergent plate boundary environment. Here we show that combined geological and geophysical data in northeastern Antarctica support the post-rift southeastward reactivation of the passive margin east of 139 °E along intraplate right-lateral strike-slip deformation belts. These deformation belts include oceanic transform faults and their collinear oceanic fracture zone and continental shear zone extensions. A striking consequence is that there is intraplate accommodation of transform fault slip in this region of Earth's surface along fracture zones and a long-active region of intracontinental deformation that is 'reusing' prior plate boundary fault zones. As the intraplate termination of plate boundary transform faulting is not predicted by classical plate tectonic theory; this region is one of the most clear examples of the transition from rigid to semi-rigid plate tectonic deformation during the formation and long-lived incubation of a potential new plate boundary.

  11. Systematic variations in morphological characteristics of global transform faults

    NASA Astrophysics Data System (ADS)

    Zhang, F.; Lin, J.

    2015-12-01

    We quantify systematic variations in morphological characteristics of global transform faults and investigate their dependence on spreading rate, local magma supply, and other tectonic variables. Detailed analyses were conducted on 78 transform faults where high-resolution multibeam bathymetry data are available. The investigated transform systems span a wide range of spreading rate and local magma supply, including examples from the East Pacific Rise, Juan de Fuca Ridge, Chile Rise, Pacific-Antarctic Ridge, Southeast Indian Ridge, Central Indian Ridge, Mid-Atlantic Ridge, American-Antarctic Ridge, Southwest Indian Ridge, and other systems. The analyses revealed systematic global and local variations in transform morphological characteristics: (1) The average transform age offset and depths shows a moderate increase with decreasing spreading rate: 1.0 Ma and 3.6 km (s = 0.21 km), 1.5 Ma (s = 0.9 Ma) and 3.8 km (s = 0.12 km), 2.2 Ma (s = 1.7 Ma and 4.5 km (s = 0.14 km), and 5.3 Ma (s = 3.5 Ma) and 4.8 km (s = 0.20 km) for the fast, intermediate fast, slow, and ultraslow ridges, respectively, corresponding to average transform length of 111 km (s = 75 km), 81 km (s = 73 km), 71 km (s = 40 km), and 92 km (s = 49 km), respectively. (2) Morphological "hooks", i.e., axial morphological highs that curve around a ridge-transform intersection, appear to be most distinctive in regions of relatively robust magma supply, especially at fast and intermediate fast ridges. (3) In contrast, "nodal basins" usually develop at the ridge-transform intersection of relatively slow spreading systems and low magma supply. The depth of the nodal basin appears to moderately increase with decreasing spreading rate with an average depth of 3.8 km (s = 0.5 km) for the investigated systems. Thus the calculated values of average transform fault depth, ridge-transform intersection depth, and age-offset of the investigated systems all appear to increase with decreasing spreading rate. However, the

  12. Transform Faults, Oceanic Ridges, and Magnetic Anomalies Southwest of Vancouver Island.

    PubMed

    Wilson, J T

    1965-10-22

    The San Andreas Fault and a large fault off British Columbia are interpreted as examples of the recently proposed "transform faults." They are joined by a short, isolated length of oceanic ridge striking N20 degrees E, with an associated "window" of young crust. The displacement along these faults is estimated at 400 kilometers. PMID:17842753

  13. Seismic structure of the Arava Fault, Dead Sea Transform

    NASA Astrophysics Data System (ADS)

    Maercklin, Nils

    2004-07-01

    The Dead Sea Transform (DST) is a prominent shear zone in the Middle East. It separates the Arabian plate from the Sinai microplate and stretches from the Red Sea rift in the south via the Dead Sea to the Taurus-Zagros collision zone in the north. Formed in the Miocene 17 Ma ago and related to the breakup of the Afro-Arabian continent, the DST accommodates the left-lateral movement between the two plates. The study area is located in the Arava Valley between the Dead Sea and the Red Sea, centered across the Arava Fault (AF), which constitutes the major branch of the transform in this region. A set of seismic experiments comprising controlled sources, linear profiles across the fault, and specifically designed receiver arrays reveals the subsurface structure in the vicinity of the AF and of the fault zone itself down to about 3-4 km depth. A tomographically determined seismic P-velocity model shows a pronounced velocity contrast near the fault with lower velocities on the western side than east of it. Additionally, S-waves from local earthquakes provide an average P-to-S velocity ratio in the study area, and there are indications for a variations across the fault. High-resolution tomographic velocity sections and seismic reflection profiles confirm the surface trace of the AF, and observed features correlate well with fault-related geological observations. Coincident electrical resistivity sections from magnetotelluric measurements across the AF show a conductive layer west of the fault, resistive regions east of it, and a marked contrast near the trace of the AF, which seems to act as an impermeable barrier for fluid flow. The correlation of seismic velocities and electrical resistivities lead to a characterisation of subsurface lithologies from their physical properties. Whereas the western side of the fault is characterised by a layered structure, the eastern side is rather uniform. The vertical boundary between the western and the eastern units seems to be

  14. Direct transformation of vacancy voids to stacking fault tetrahedra.

    PubMed

    Uberuaga, B P; Hoagland, R G; Voter, A F; Valone, S M

    2007-09-28

    Defect accumulation is the principal factor leading to the swelling and embrittlement of materials during irradiation. It is commonly assumed that, once defect clusters nucleate, their structure remains essentially constant while they grow in size. Here, we describe a new mechanism, discovered during accelerated molecular dynamics simulations of vacancy clusters in fcc metals, that involves the direct transformation of a vacancy void to a stacking fault tetrahedron (SFT) through a series of 3D structures. This mechanism is in contrast with the collapse to a 2D Frank loop which then transforms to an SFT. The kinetics of this mechanism are characterized by an extremely large rate prefactor, tens of orders of magnitude larger than is typical of atomic processes in fcc metals.

  15. Analysis of complex faulting: Wavelet transform, multiple datasets and realistic fault geometry

    NASA Astrophysics Data System (ADS)

    Ji, Chen

    This thesis presents the studies of two recent large and well-recorded earthquakes, the 1999 Hector Mine and Chi-Chi earthquakes. A new procedure for the determination of rupture complexity from a joint inversion of static and seismic data was first developed. This procedure applies a wavelet transform to separate seismic information related to the spatial and temporal slip history, then uses a simulated annealing algorithm to determine the finite-fault model that minimizes the objective function described in terms of wavelet coefficients. This method is then applied to simultaneously invert the slip amplitude, slip direction, rise time and rupture velocity distributions of the Hector Mine and Chi-Chi earthquakes with both seismic and geodetic data. Two slip models are later verified with independent datasets. Results indicate that the seismic moment of the Hector Mine earthquake is 6.28 x 1019 Nm, which is distributed along a "Y" shape fault geometry with three segments. The average slip is 1.5 m with peak amplitudes as high as 7 m. The fault rupture has an average slip duration of 3.5 sec and a slow average rupture velocity of 1.9 km/sec, resulting in a 14 sec rupture propagation history. The rise time appears to be roughly proportional to slip, and the two branches of "Y" shape fault rupture together. The Chi-Chi earthquake is the best-recorded large earthquake so far. Its seismic moment of 2.7 x 1020 Nm is concentrated on the surface of a "wedge shaped" block. The rupture front propagates with a slow rupture velocity of about 2.0 km/sec. The average slip duration is 7.2 sec. Four interesting results are obtained: (1) The sinuous fault plane strongly affects both spatial and temporal variation in slip history; (2) Long-period peak slip velocity increases as the rupture propagates; (3) The peak slip velocity near the surface is in general higher than on the deeper portion of the fault plane as predicted by dynamic modeling [e.g., Oglesby et al., 1998]; and (4

  16. Rheology and friction along the Vema transform fault (Central Atlantic) inferred by thermal modeling

    NASA Astrophysics Data System (ADS)

    Cuffaro, Marco; Ligi, Marco

    2016-04-01

    We investigate with 3-D finite element simulations the temperature distribution beneath the Vema transform that offsets the Mid-Atlantic Ridge by ~300 km in the Central Atlantic. The developed thermal model includes the effects of mantle flow beneath a ridge-transform-ridge geometry and the lateral heat conduction across the transform fault, and of the shear heating generated along the fault. Numerical solutions are presented for a 3-D domain, discretized with a non-uniform tetrahedral mesh, where relative plate kinematics is used as boundary condition, providing passive mantle upwelling. Mantle is modelled as a temperature-dependent viscous fluid, and its dynamics can be described by Stokes and advection-conduction heat equations. The results show that shear heating raises significantly the temperature along the transform fault. In order to test model results, we calculated the thermal structure simulating the mantle dynamics beneath an accretionary plate boundary geometry that duplicates the Vema transform fault, assuming the present-day spreading rate and direction of the Mid Atlantic Ridge at 11 °N. Thus, the modelled heat flow at the surface has been compared with 23 heat flow measurements carried out along the Vema Transform valley. Laboratory studies on the frictional stability of olivine aggregates show that the depth extent of oceanic faulting is thermally controlled and limited by the 600 °C isotherm. The depth of isotherms of the thermal model were compared to the depths of earthquakes along transform faults. Slip on oceanic transform faults is primarily aseismic, only 15% of the tectonic offset is accommodated by earthquakes. Despite extensive fault areas, few large earthquakes occur on the fault and few aftershocks follow large events. Rheology constrained by the thermal model combined with geology and seismicity of the Vema Transform fault allows to better understand friction and the spatial distribution of strength along the fault and provides

  17. The relationship between oceanic transform fault segmentation, seismicity, and thermal structure

    NASA Astrophysics Data System (ADS)

    Wolfson-Schwehr, Monica

    Mid-ocean ridge transform faults (RTFs) are typically viewed as geometrically simple, with fault lengths readily constrained by the ridge-transform intersections. This relative simplicity, combined with well-constrained slip rates, make them an ideal environment for studying strike-slip earthquake behavior. As the resolution of available bathymetric data over oceanic transform faults continues to improve, however, it is being revealed that the geometry and structure of these faults can be complex, including such features as intra-transform pull-apart basins, intra-transform spreading centers, and cross-transform ridges. To better determine the resolution of structural complexity on RTFs, as well as the prevalence of RTF segmentation, fault structure is delineated on a global scale. Segmentation breaks the fault system up into a series of subparallel fault strands separated by an extensional basin, intra-transform spreading center, or fault step. RTF segmentation occurs across the full range of spreading rates, from faults on the ultraslow portion of the Southwest Indian Ridge to faults on the ultrafast portion of the East Pacific Rise (EPR). It is most prevalent along the EPR, which hosts the fastest spreading rates in the world and has undergone multiple changes in relative plate motion over the last couple of million years. Earthquakes on RTFs are known to be small, to scale with the area above the 600°C isotherm, and to exhibit some of the most predictable behaviors in seismology. In order to determine whether segmentation affects the global RTF scaling relations, the scalings are recomputed using an updated seismic catalog and fault database in which RTF systems are broken up according to their degree of segmentation (as delineated from available bathymetric datasets). No statistically significant differences between the new computed scaling relations and the current scaling relations were found, though a few faults were identified as outliers. Finite element

  18. Tectonic evolution of the gulf of Aqaba-Dead Sea transform fault system

    NASA Astrophysics Data System (ADS)

    Barjous, M.; Mikbel, Sh

    1990-08-01

    Neogene tectonic phases related to stresses which created the Gulf of Aqaba-Dead Sea transform fault system were recorded from evidence in the central part of the Wadi Araba. The chronological sequence of deformation stages is as follows: (1) Epeirogeny (latest late Eocene-Oligocene). (2) Faulting and warping (?Oligocene-Middle Miocene). (3) Folding striking between north-northeast and northeast, E-W trending and N-S shear faulting, and NW-SE normal faulting (Miocene). (4) Uplift and faulting (Pliocene-Pleistocene). (5) Faulting with volcanic activity (Pleistocene). (6) Sinistral movement along the major shear fault in the Wadi Araba. Indications are that this phase is still active (Pleistocene-Recent). The re-strain phases recognised are clues for the investigated area and the entire region to the understanding of the tectonic evolution of the Gulf of Aqaba-Dead Sea transform. Structural features contributing to evidence of strike-slip movement are: drag folds, reverse and normal flower structures, alternation of the downthrown side along the fault trace, gently waved vertical fault planes, horizontal slickensides, transpressive and transtensional pressure ridges and rhombs, linear fault traces without marked vertical throw, and fault plane ridges. A sinistral offset of 40 km along the N-S Al Quweira Fault was deduced from the displacement of distinctive andesitic rocks found on both sides of the fault. For the E-W Salawan Fault, a dextral movement of at least 7 km was determined from the offset of formation boundaries. North-northeast-striking deformed belts containing monoclinal to recumbent en-echelon folds can be seen in the Gulf of Aqaba-Dead Sea transform fault zone. The axial planes of the folds dip southeast and face northwest. These structural elements indicate local SE-NW compressional stress.

  19. Geochemistry of Intra-Transform Lavas from the Galápagos Transform Fault

    NASA Astrophysics Data System (ADS)

    Morrow, T. A.; Mittelstaedt, E. L.; Harpp, K. S.

    2013-12-01

    The Galápagos plume has profoundly affected the development and evolution of the nearby (<250 km) Galápagos Transform Fault (GTF), a ~100km right-stepping offset in the Galápagos Spreading Center (GSC). The GTF can be divided into two sections that represent different stages of transform evolution: the northern section exhibits fully developed transform fault morphology, whereas the southern section is young, and deformation is more diffuse. Both segments are faulted extensively and include numerous small (<0.5km3) monogenetic volcanic cones, though volcanic activity is more common in the south. To examine the composition of the mantle source and melting conditions responsible for the intra-transform lavas, as well as the influence of the plume on GTF evolution, we present major element, trace element, and radiogenic isotope analysis of samples collected during SON0158, EWI0004, and MV1007 cruises. Radiogenic isotope ratio variations in the Galápagos Archipelago require four distinct mantle reservoirs across the region: PLUME, DM, FLO, and WD. We find that Galápagos Transform lavas are chemically distinct from nearby GSC lavas and neighboring seamounts. They have radiogenic isotopic compositions that lie on a mixing line between DM and PLUME, with little to no contribution from any other mantle reservoirs despite their geographic proximity to WD-influenced lavas erupted along the GSC and at nearby (<50km away) seamounts. Within the transform, lavas from the northern section are more enriched in radiogenic isotopes than lavas sampled in the southern section. Transform lavas are anomalously depleted in incompatible trace elements (ITEs) relative to GSC lavas, suggesting unique melting conditions within the transform. Isotopic variability along the transform axis indicates that mantle sources and/or melting mechanisms vary between the northern and southern sections, which may relate to their distances from the plume or the two-stage development and evolution of

  20. Transformer Incipient Fault Prediction Using Combined Artificial Neural Network and Various Particle Swarm Optimisation Techniques

    PubMed Central

    2015-01-01

    It is important to predict the incipient fault in transformer oil accurately so that the maintenance of transformer oil can be performed correctly, reducing the cost of maintenance and minimise the error. Dissolved gas analysis (DGA) has been widely used to predict the incipient fault in power transformers. However, sometimes the existing DGA methods yield inaccurate prediction of the incipient fault in transformer oil because each method is only suitable for certain conditions. Many previous works have reported on the use of intelligence methods to predict the transformer faults. However, it is believed that the accuracy of the previously proposed methods can still be improved. Since artificial neural network (ANN) and particle swarm optimisation (PSO) techniques have never been used in the previously reported work, this work proposes a combination of ANN and various PSO techniques to predict the transformer incipient fault. The advantages of PSO are simplicity and easy implementation. The effectiveness of various PSO techniques in combination with ANN is validated by comparison with the results from the actual fault diagnosis, an existing diagnosis method and ANN alone. Comparison of the results from the proposed methods with the previously reported work was also performed to show the improvement of the proposed methods. It was found that the proposed ANN-Evolutionary PSO method yields the highest percentage of correct identification for transformer fault type than the existing diagnosis method and previously reported works. PMID:26103634

  1. Transformer Incipient Fault Prediction Using Combined Artificial Neural Network and Various Particle Swarm Optimisation Techniques.

    PubMed

    Illias, Hazlee Azil; Chai, Xin Rui; Abu Bakar, Ab Halim; Mokhlis, Hazlie

    2015-01-01

    It is important to predict the incipient fault in transformer oil accurately so that the maintenance of transformer oil can be performed correctly, reducing the cost of maintenance and minimise the error. Dissolved gas analysis (DGA) has been widely used to predict the incipient fault in power transformers. However, sometimes the existing DGA methods yield inaccurate prediction of the incipient fault in transformer oil because each method is only suitable for certain conditions. Many previous works have reported on the use of intelligence methods to predict the transformer faults. However, it is believed that the accuracy of the previously proposed methods can still be improved. Since artificial neural network (ANN) and particle swarm optimisation (PSO) techniques have never been used in the previously reported work, this work proposes a combination of ANN and various PSO techniques to predict the transformer incipient fault. The advantages of PSO are simplicity and easy implementation. The effectiveness of various PSO techniques in combination with ANN is validated by comparison with the results from the actual fault diagnosis, an existing diagnosis method and ANN alone. Comparison of the results from the proposed methods with the previously reported work was also performed to show the improvement of the proposed methods. It was found that the proposed ANN-Evolutionary PSO method yields the highest percentage of correct identification for transformer fault type than the existing diagnosis method and previously reported works.

  2. Variations in earthquake rupture properties along the Gofar transform fault, East Pacific Rise

    NASA Astrophysics Data System (ADS)

    McGuire, Jeffrey J.; Collins, John A.; Gouédard, Pierre; Roland, Emily; Lizarralde, Dan; Boettcher, Margaret S.; Behn, Mark D.; van der Hilst, Robert D.

    2012-05-01

    On a global scale, seismicity on oceanic transform faults that link mid-ocean ridge segments is thermally controlled. However, temperature cannot be the only control because the largest earthquakes on oceanic transform faults rupture only a small fraction of the area that thermal models predict to be capable of rupture. Instead, most slip occurs without producing large earthquakes. When large earthquakes do occur, they often repeat quasiperiodically. Moreover, oceanic transform faults produce an order of magnitude more foreshocks than continental strike-slip faults. Here we analyse a swarm of about 20,000 foreshocks, recorded on an array of ocean-bottom seismometers, which occurred before a magnitude 6.0 earthquake on the Gofar transform fault, East Pacific Rise. We find that the week-long foreshock sequence was confined to a 10-km-long region that subsequently acted as a barrier to rupture during the mainshock. The foreshock zone is associated with a high porosity and undergoes a 3% decrease in average shear-wave speed during the week preceding the mainshock. We conclude that the material properties of fault segments capable of rupturing in large earthquakes differ from those of barrier regions, possibly as a result of enhanced fluid circulation within the latter. We suggest that along-strike variations in fault zone material properties can help explain the abundance of foreshocks and the relative lack of large earthquakes that occur on mid-ocean ridge transform faults.

  3. The effect of porosity on fault slip mechanisms at East Pacific Rise transform faults: insight from observations and models at the Gofar Fault (Invited)

    NASA Astrophysics Data System (ADS)

    Roland, E. C.; McGuire, J. J.; Lizarralde, D.; Behn, M. D.; Collins, J. A.

    2013-12-01

    In this study, we combine recent local observations and numerical models to show that Pacific oceanic transform faults contain consistent high-porosity damage zones that extend throughout the crust within localized regions along the fault. Heterogeneity in fault zone material properties associated with along-strike changes in porosity and fluid-related effects may promote variations in fault-slip mechanisms, with slow, aseismic slip in some fault segments and fast, seismic rupture in others. Ocean bottom seismometer observations made during the 2008 rupture process of the Gofar fault (4° S on the East Pacific Rise), in combination with ~25 years of teleseismic observations, indicate significant along-strike variability in fault slip mechanisms; discrete fault segments fail regularly in Mw 6.0 earthquakes, and seismogenic segments are separated by velocity-strengthening, ~10-km-long rupture barriers that appear to fail during earthquake swarms, likely accompanied by aseismic slip. 3D models of the Gofar fault thermal structure suggest that swarm microearthquake hypocenters within the rupture barrier zones occur at depths greater than would be expected to sustain brittle failure, and at temperatures too hot to exhibit stick-slip behavior in lower crust and upper mantle rocks. This observation suggests that some mechanism leads to enhanced cooling within discrete zones along the fault. The seismic structure of the Gofar rupture barrier region is imaged using P-wave traveltime tomography as a ~2-km-wide low velocity zone that extends through the entire crust. Reduced velocities can be explained if the plate-boundary region is composed of fault material with enhanced fluid-filled porosity (1.5-8%). Enhanced porosity, and associated increased hydrothermal heat transport deep within the crust at Gofar is also consistent with the observed deep seismicity and apparently cooler fault structure in distinct fault segments. Dilatency strengthening is one mechanism that may be

  4. Double fault detection of cone-shaped redundant IMUs using wavelet transformation and EPSA.

    PubMed

    Lee, Wonhee; Park, Chan Gook

    2014-02-19

    A model-free hybrid fault diagnosis technique is proposed to improve the performance of single and double fault detection and isolation. This is a model-free hybrid method which combines the extended parity space approach (EPSA) with a multi-resolution signal decomposition by using a discrete wavelet transform (DWT). Conventional EPSA can detect and isolate single and double faults. The performance of fault detection and isolation is influenced by the relative size of noise and fault. In this paper; the DWT helps to cancel the high frequency sensor noise. The proposed technique can improve low fault detection and isolation probability by utilizing the EPSA with DWT. To verify the effectiveness of the proposed fault detection method Monte Carlo numerical simulations are performed for a redundant inertial measurement unit (RIMU).

  5. Phase transformation and nanometric flow cause extreme weakening during fault slip

    NASA Astrophysics Data System (ADS)

    Green, H. W., II; Shi, F.; Bozhilov, K.; Xia, G.; Reches, Z.

    2015-06-01

    Earthquake instability requires fault weakening during slip. The mechanism of this weakening is central to understanding earthquake sliding and, in many cases, has been attributed to fluids. It is also unclear why major faults such as the San Andreas Fault do not exhibit significant thermal anomalies due to shear heating during sliding and whether or not fault rocks that have been melted--pseudotachylytes--are rare. High-speed friction experiments on a wide variety of rock types have shown that they all exhibit extreme weakening and that the sliding surface is nanometric and contains phases not present at the start. Here we use electron microscopy to examine these two key observations in high-speed friction experiments and compare them with high-pressure faulting experiments. We show that phase transformations occur in both cases and that they are associated with profound weakening. However, fluid is not necessary for such weakening; the nanometric fault filling is inherently weak at seismic sliding rates and it flows by grain boundary sliding. These observations suggest that pseudotachylytes are rare in nature because shear-heating-induced endothermic reactions in fault zones prevent temperature rise to melting. Microstructures preserved in the Punchbowl Fault, an ancestral branch of the San Andreas Fault, suggest similar processes during natural faulting and offer an explanation for the lack of a thermal aureole around major faults.

  6. Interaction between transform faults and rift systems: a combined field and experimental approach

    NASA Astrophysics Data System (ADS)

    Tibaldi, Alessandro; Bonali, Fabio; Pasquaré Mariotto, Federico

    2016-04-01

    We present a detailed field structural survey of the area of interaction between the active NW-striking transform Husavik-Flatey Fault (HFF) and the N-S Theystareykir Fissure Swarm (TFS), in North Iceland, integrated by analogue scaled models. Field data contribute to a better understanding of how transform faults work, at a much higher detail than classical marine geophysical studies. Analogue experiments are conducted to analyse the fracture patterns resulting from different possible cases where transform faulting accompanies or postpones the rift motions; different tectonic block configurations are also considered. West of the intersection between the transform fault (HFF) and the rift zone (TFS), the former splays with a gradual bending giving rise to a leading extensional imbricate fan. The westernmost structure of the rift, the N-S Gudfinnugja Fault (GF), is divided into two segments: the southern segment makes a junction with the HFF and is part of the imbricate fan; north of the junction instead, the northern GF appears right-laterally offset by about 20 m. Southeast of the junction, along the possible prolongation of the HFF across the TFS, the strike of the rift faults rotates in an anticlockwise direction, attaining a NNW-SSE orientation. Moreover, the TFS faults north of the HFF prolongation are fewer and have smaller offsets than those located to the south. Through the comparison between the structural data collected in the field at the HFF-TFS connection zone and a set of scaled experiments, we confirm a prolongation of the HFF through the rift, although here the transform fault has a much lower slip-rate than west of the junction. Our data suggest that transform fault terminations may be more complex than previously known, and propagate across a rift through a modification of the rift pattern.

  7. Magnetic character of a large continental transform: an aeromagnetic survey of the Dead Sea Fault

    USGS Publications Warehouse

    ten Brink, Uri S.; Rybakov, Michael; Al-Zoubi, Abdallah S.; Rotstein, Yair

    2007-01-01

    New high-resolution airborne magnetic (HRAM) data along a 120-km-long section of the Dead Sea Transform in southern Jordan and Israel shed light on the shallow structure of the fault zone and on the kinematics of the plate boundary. Despite infrequent seismic activity and only intermittent surface exposure, the fault is delineated clearly on a map of the first vertical derivative of the magnetic intensity, indicating that the source of the magnetic anomaly is shallow. The fault is manifested by a 10–20 nT negative anomaly in areas where the fault cuts through magnetic basement and by a

  8. A method of real-time fault diagnosis for power transformers based on vibration analysis

    NASA Astrophysics Data System (ADS)

    Hong, Kaixing; Huang, Hai; Zhou, Jianping; Shen, Yimin; Li, Yujie

    2015-11-01

    In this paper, a novel probability-based classification model is proposed for real-time fault detection of power transformers. First, the transformer vibration principle is introduced, and two effective feature extraction techniques are presented. Next, the details of the classification model based on support vector machine (SVM) are shown. The model also includes a binary decision tree (BDT) which divides transformers into different classes according to health state. The trained model produces posterior probabilities of membership to each predefined class for a tested vibration sample. During the experiments, the vibrations of transformers under different conditions are acquired, and the corresponding feature vectors are used to train the SVM classifiers. The effectiveness of this model is illustrated experimentally on typical in-service transformers. The consistency between the results of the proposed model and the actual condition of the test transformers indicates that the model can be used as a reliable method for transformer fault detection.

  9. SeaMARC II mapping of transform faults in the Cayman Trough, Caribbean Sea

    USGS Publications Warehouse

    Rosencrantz, Eric; Mann, Paul

    1992-01-01

    SeaMARC II maps of the southern wall of the Cayman Trough between Honduras and Jamaica show zones of continuous, well-defined fault lineaments adjacent and parallel to the wall, both to the east and west of the Cayman spreading axis. These lineaments mark the present, active traces of transform faults which intersect the southern end of the spreading axis at a triple junction. The Swan Islands transform fault to the west is dominated by two major lineaments that overlap with right-stepping sense across a large push-up ridge beneath the Swan Islands. The fault zone to the east of the axis, named the Walton fault, is more complex, containing multiple fault strands and a large pull-apart structure. The Walton fault links the spreading axis to Jamaican and Hispaniolan strike-slip faults, and it defines the southern boundary of a microplate composed of the eastern Cayman Trough and western Hispaniola. The presence of this microplate raises questions about the veracity of Caribbean plate velocities based primarily on Cayman Trough opening rates.

  10. Rupture process of oceanic transform faults linked to material variability: local observations and models of the Gofar Fault, EPR

    NASA Astrophysics Data System (ADS)

    Roland, E. C.; McGuire, J. J.; Collins, J. A.; Lizarralde, D.; Liu, Y.; Behn, M. D.

    2011-12-01

    We present the first comprehensive study of the rupture process associated with the end of the earthquake cycle on a mid-ocean ridge transform fault (RTF) and consider it in the context of the detailed fault zone thermal and mechanical properties and seismic velocity structure. Seismicity that occurred during the 2008 rupture event on the western-most segment of the Gofar Fault on the East Pacific Rise included a Mw 6.0 mainshock earthquake, preceded by a prolific foreshock sequence, and followed months later by an earthquake swarm, each on discrete sections of the fault. These events were captured by a local array of ocean bottom seismometers and strong motion accelerometers, and for the first time, details of the spatial distribution of seismic slip provide insight into many outstanding questions that exist about RTF fault mechanics. While thermal rheologies work well at predicting the size of earthquakes on continents and along subduction zones, at oceanic transform faults low average seismic coupling estimates suggest that other factors must influence the mechanical behavior. We present the observed earthquake distribution along with a new, more realistic thermal model developed for the Gofar fault that improves upon the halfspace cooling model typically used to estimate the RTF thermal structure and thermally controlled seismogenic area. The 3D temperature structure is calculated using a visco-plastic rheology with non-Newtonian viscous mantle flow, shear heating, and hydrothermal circulation. Fault slip over multiple earthquake cycles is modeled in the rate and state friction framework using gabbro friction data and the new Gofar thermal model. We also present the seismic velocity structure, determined using arrival time tomography from a wide-angle refraction survey across the foreshock zone that illuminates a significant low velocity damage zone associated with the central Gofar Fault. Reduced seismic velocities at the base of the crust within the

  11. Oceanic ridges and transform faults: Their intersection angles and resistance to plate motion

    USGS Publications Warehouse

    Lachenbruch, A.H.; Thompson, G.A.

    1972-01-01

    The persistent near-orthogonal pattern formed by oceanic ridges and transform faults defies explanation in terms of rigid plates because it probably depends on the energy associated with deformation. For passive spreading, it is likely that the ridges and transforms adjust to a configuration offering minimum resistance to plate separation. This leads to a simple geometric model which yields conditions for the occurrence of transform faults and an aid to interpretation of structural patterns in the sea floor. Under reasonable assumptions, it is much more difficult for diverging plates to spread a kilometer of ridge than to slip a kilometer of transform fault, and the patterns observed at spreading centers might extend to lithospheric depths. Under these conditions, the resisting force at spreading centers could play a significant role in the dynamics of plate-tectonic systems. ?? 1972.

  12. Transform Faults and Lithospheric Structure: Insights from Numerical Models and Shipboard and Geodetic Observations

    NASA Astrophysics Data System (ADS)

    Takeuchi, Christopher S.

    In this dissertation, I study the influence of transform faults on the structure and deformation of the lithosphere, using shipboard and geodetic observations as well as numerical experiments. I use marine topography, gravity, and magnetics to examine the effects of the large age-offset Andrew Bain transform fault on accretionary processes within two adjacent segments of the Southwest Indian Ridge. I infer from morphology, high gravity, and low magnetization that the extremely cold and thick lithosphere associated with the Andrew Bain strongly suppresses melt production and crustal emplacement to the west of the transform fault. These effects are counteracted by enhanced temperature and melt production near the Marion Hotspot, east of the transform fault. I use numerical models to study the development of lithospheric shear zones underneath continental transform faults (e.g. the San Andreas Fault in California), with a particular focus on thermomechanical coupling and shear heating produced by long-term fault slip. I find that these processes may give rise to long-lived localized shear zones, and that such shear zones may in part control the magnitude of stress in the lithosphere. Localized ductile shear participates in both interseismic loading and postseismic relaxation, and predictions of models including shear zones are within observational constraints provided by geodetic and surface heat flow data. I numerically investigate the effects of shear zones on three-dimensional postseismic deformation. I conclude that the presence of a thermally-activated shear zone minimally impacts postseismic deformation, and that thermomechanical coupling alone is unable to generate sufficient localization for postseismic relaxation within a ductile shear zone to kinematically resemble that by aseismic fault creep (afterslip). I find that the current record geodetic observations of postseismic deformation do not provide robust discriminating power between candidate linear and

  13. Shallow architecture of the Wadi Araba fault (Dead Sea Transform) from high-resolution seismic investigations

    NASA Astrophysics Data System (ADS)

    Haberland, Ch.; Maercklin, N.; Kesten, D.; Ryberg, T.; Janssen, Ch.; Agnon, A.; Weber, M.; Schulze, A.; Qabbani, I.; El-Kelani, R.

    2007-03-01

    In a high-resolution small-scale seismic experiment we investigated the shallow structure of the Wadi Araba fault (WAF), the principal fault strand of the Dead Sea Transform System between the Gulf of Aqaba/Eilat and the Dead Sea. The experiment consisted of 8 sub-parallel 1 km long seismic lines crossing the WAF. The recording station spacing was 5 m and the source point distance was 20 m. The first break tomography yields insight into the fault structure down to a depth of about 200 m. The velocity structure varies from one section to the other which were 1 to 2 km apart, but destinct velocity variations along the fault are visible between several profiles. The reflection seismic images show positive flower structures and indications for different sedimentary layers at the two sides of the main fault. Often the superficial sedimentary layers are bent upward close to the WAF. Our results indicate that this section of the fault (at shallow depths) is characterized by a transpressional regime. We detected a 100 to 300 m wide heterogeneous zone of deformed and displaced material which, however, is not characterized by low seismic velocities at a larger scale. At greater depth the geophysical images indicate a blocked cross-fault structure. The structure revealed, fault cores not wider than 10 m, are consistent with scaling from wear mechanics and with the low loading to healing ratio anticipated for the fault.

  14. Foreshock sequences and short-term earthquake predictability on East Pacific Rise transform faults.

    PubMed

    McGuire, Jeffrey J; Boettcher, Margaret S; Jordan, Thomas H

    2005-03-24

    East Pacific Rise transform faults are characterized by high slip rates (more than ten centimetres a year), predominantly aseismic slip and maximum earthquake magnitudes of about 6.5. Using recordings from a hydroacoustic array deployed by the National Oceanic and Atmospheric Administration, we show here that East Pacific Rise transform faults also have a low number of aftershocks and high foreshock rates compared to continental strike-slip faults. The high ratio of foreshocks to aftershocks implies that such transform-fault seismicity cannot be explained by seismic triggering models in which there is no fundamental distinction between foreshocks, mainshocks and aftershocks. The foreshock sequences on East Pacific Rise transform faults can be used to predict (retrospectively) earthquakes of magnitude 5.4 or greater, in narrow spatial and temporal windows and with a high probability gain. The predictability of such transform earthquakes is consistent with a model in which slow slip transients trigger earthquakes, enrich their low-frequency radiation and accommodate much of the aseismic plate motion. PMID:15791246

  15. Weak fault signature extraction of rotating machinery using flexible analytic wavelet transform

    NASA Astrophysics Data System (ADS)

    Zhang, ChunLin; Li, Bing; Chen, BinQiang; Cao, HongRui; Zi, YanYang; He, ZhengJia

    2015-12-01

    Extracting and revealing the weak periodic fault vibration impulses is reasonable for damage detection of rotating machinery. However, the widely used dyadic WT suffers fixed frequency partition manner and low oscillating bases which would weaken its performance in weak fault detection. A new method based on flexible analytic wavelet transform (FAWT) is proposed in this article. Employing fractional and arbitrary scaling and translation factors, FAWT possesses attractive properties such as flexible time-frequency (TF) covering manner, better shift-invariance and tunable oscillatory nature of the bases, offering proper wavelet frame and bases shape to match the weak fault components. Moreover, FAWT is effective in revealing the amplitude modulation feature of the periodic fault impulses that occur in some damaged rotating components. The applications to a rolling bearing, a planetary gearbox of, and a flue gas turbine unit show that the proposed method is effective in extracting weak impulsive fault signature.

  16. Structure and topography of the Siqueiros transform fault system: Evidence for the development of intra-transform spreading centers

    NASA Astrophysics Data System (ADS)

    Fornari, Daniel J.; Gallo, David G.; Edwards, Margo H.; Madsen, John A.; Perfit, Michael R.; Shor, Alexander N.

    1989-12-01

    The Siqueiros transform fault system, which offsets the East Pacific Rise between 8°20'N 8°30'N, has been mapped with the Sea MARC II sonar system and is found to consist of four intra-transform spreading centers and five strike-slip faults. The bathymetric and side-looking sonar data define the total width of the transform domain to be ≈20km. The transform domain includes prominent topographic features that are related to either seafloor spreading processes at the short spreading centers or shearing along the bounding faults. The spreading axes and the seafloor on the flanks of each small spreading center comprise morphological and structural features which suggest that the two western spreading centers are older than the eastern spreading centers. Structural data for the Clipperton, Orozco and Siqueiros transforms, indicate that the relative plate motion geometry of the Pacific-Cocos plate boundary has been stable for the past ≈1.5 Ma. Because the seafloor spreading fabric on the flanks of the western spreading centers is ≈500 000 years old and parallels the present EPR abyssal hill trend (350°) we conclude that a small change in plate motion was not the cause for intra-transform spreading center development in Siqueiros. We suggest that the impetus for the development of intra-transform spreading centers along the Siqueiros transform system was provided by the interaction of small melt anomalies in the mantle (SMAM) with deepseated, throughgoing lithospheric fractures within the shear zone. Initially, eruption sites may have been preferentially located along strike-slip faults and/or along cross-faults that eventually developed into pull-apart basins. Spreading centers C and D in the eastern portion of Siqueiros are in this initial pull-apart stage. Continued intrusion and volcanism along a short ridge within a pull-apart basin may lead to the formation of a stable, small intra-transform spreading center that creates a narrow swath of ridge

  17. Active tectonics along the Wadi Araba-Jordan Valley transform fault

    NASA Astrophysics Data System (ADS)

    Galli, Paolo

    1999-02-01

    A geological study has been carried out along the 200 km long Wadi Araba following the transform fault that separates the Arabian and Sinai-African Plates. Recent movements along this structure affect upper Pleistocene-Holocene deposits and archaeological sites. Kinematic indicators show sinistral strike-slip and oblique movements, in agreement with the relative motion between the two plates. Other evidence of recent horizontal displacement exists along the Jordan Valley Fault, both on the Dead Sea-Lake Tiberias segment and on the segment north of Lake Tiberias. A minimum horizontal slip rate of 1 cm yr-1 has been estimated for both the southern segment of the Wadi Araba Fault and for the southern Jordan River Fault. The two faults can be roughly subdivided into at least four segments: two in the Wadi Araba (80 km long each), one from the Dead Sea to Lake Tiberias (130 km), and one from Lake Tiberias to the Hula graben (>30 km). Faulting may also occur along shorter subsegments, as shown by bends in the Wadi Araba-Jordan River Fault and by the growth of local compression and extension features. Instrument-recorded seismicity appears to be mainly concentrated along some of these subsegments. A comparison between the observed seismic and field-determined slip rates across the fault indicates possible strain accumulation during the last 2000 years.

  18. Thermal-Mechanical Behavior of Oceanic Transform Faults- Implications for Hydration of the Upper Oceanic Mantle

    NASA Astrophysics Data System (ADS)

    Roland, E. C.; Behn, M. D.; Hirth, G.

    2004-12-01

    The presence of water at oceanic transform faults influences the thermal structure, rheology, and petrology of the upper mantle. Serpentinization at ridges and transforms plays an important role for the large-scale water budget of the mantle and eventual flux melting that is responsible for arc volcanism at convergent margins. The extent to which hydrous minerals (e.g., serpentine and talc) are incorporated into the upper mantle at oceanic transform faults is highly dependent on the thermal structure and stress state. Previous numerical modeling studies have suggested that the mantle beneath oceanic transform faults is anomalously cold, with depressed isotherms relative to a half-space cooling model [1,2,3]. However, recent models, that incorporate brittle rheology, show that transform faults may represent a region of enhanced mantle upwelling and elevated temperatures [4]. To investigate the thermal-mechanical behavior of oceanic transform faults, we utilize a 3D finite element model, assuming mantle convection, conduction, and steady-state incompressible mantle flow. Our model incorporates a non-linear viscous rheology with a visco-plastic approximation to simulate lithospheric brittle failure. The introduction of water into the lithosphere causes rheological changes with additional feedbacks on the thermal and rheologic structure such as enhanced conductive cooling and changes in frictional behavior. We incorporate the effects of these feedbacks, and our derived thermal structures are integrated with the estimated zone of permeable fluid flow to approximate the stability fields of hydrous phases in the upper mantle. Through examining a rage of parameters, including spreading rate, fault length, and the efficiency of hydrothermal circulation, we constrain the potential for transform faults to act as a source for mantle hydration, and estimate the amount of water that could be bound in hydrous phases as a result of brittle cracking at oceanic faults. 1. Furlong et

  19. Thermal-Mechanical Behavior of Oceanic Transform Faults- Implications for Hydration of the Upper Oceanic Mantle

    NASA Astrophysics Data System (ADS)

    Roland, E. C.; Behn, M. D.; Hirth, G.

    2007-12-01

    The presence of water at oceanic transform faults influences the thermal structure, rheology, and petrology of the upper mantle. Serpentinization at ridges and transforms plays an important role for the large-scale water budget of the mantle and eventual flux melting that is responsible for arc volcanism at convergent margins. The extent to which hydrous minerals (e.g., serpentine and talc) are incorporated into the upper mantle at oceanic transform faults is highly dependent on the thermal structure and stress state. Previous numerical modeling studies have suggested that the mantle beneath oceanic transform faults is anomalously cold, with depressed isotherms relative to a half-space cooling model [1,2,3]. However, recent models, that incorporate brittle rheology, show that transform faults may represent a region of enhanced mantle upwelling and elevated temperatures [4]. To investigate the thermal-mechanical behavior of oceanic transform faults, we utilize a 3D finite element model, assuming mantle convection, conduction, and steady-state incompressible mantle flow. Our model incorporates a non-linear viscous rheology with a visco-plastic approximation to simulate lithospheric brittle failure. The introduction of water into the lithosphere causes rheological changes with additional feedbacks on the thermal and rheologic structure such as enhanced conductive cooling and changes in frictional behavior. We incorporate the effects of these feedbacks, and our derived thermal structures are integrated with the estimated zone of permeable fluid flow to approximate the stability fields of hydrous phases in the upper mantle. Through examining a rage of parameters, including spreading rate, fault length, and the efficiency of hydrothermal circulation, we constrain the potential for transform faults to act as a source for mantle hydration, and estimate the amount of water that could be bound in hydrous phases as a result of brittle cracking at oceanic faults. 1. Furlong et

  20. Seismic Velocity Structure Across the Quebrada and Gofar Oceanic Transform Faults from 2D Refraction Tomography - A Comparison of Faults with High and Low Seismic Slip Deficits

    NASA Astrophysics Data System (ADS)

    Roland, E. C.; McGuire, J. J.; Collins, J. A.; Lizarralde, D.

    2009-12-01

    We perform two 2-D tomographic inversions using data collected as a part of the Quebrada-Discovery-Gofar (QDG) Transform Fault Active/Passive Experiment. The QDG transform faults are located in the southern Pacific Ocean and offset the East Pacific Rise (EPR) at approximately 4° south. In the spring of 2008, two ~100 km refraction profiles were collected, each using 8 short period Ocean Bottom Seismometers (OBS) from OBSIP and over 900 shots from the RV Marcus Langseth, across the easternmost segments of the Quebrada and Gofar transform faults. The two refraction profiles are modeled using a 2-D tomographic code that allows joint inversion of the Pg, PmP, and Pn arrivals (Korenaga et al., 2000). Variations in crustal velocity and thickness, as well as the width and depth extent of a significant low velocity zone within and below the transform valley provide some insight into the material properties of each of the fault-zones. Reduced seismic velocities that are 0.5 to over 1.0 km/s slower than velocities associated with the oceanic crust outside the fault zone may indicate the highly fractured fault zone lithology. The low velocity zone associated with the Quebrada fault also extends to the south of the active fault zone, beneath a fossil fault trace. Because Gofar is offset by an intratransform spreading center, we are able to compare ‘normal’ oceanic crust produced at the EPR to the south of the fault with crust associated with the ~15 km intratransform spreading center to the north. These two high slip rate (14 cm/yr) faults look similar morphologically and demonstrate comparable microseismicity characteristics, however their abilities to generate large earthquakes differ significantly. Gofar generates large earthquakes (Mw ~6) regularly every few years, but in the past 24 years only one large (Mw 5.6) event has been reliably located on Quebrada. The contrasting seismic behavior of these faults represents the range of behavior observed in the global

  1. Different styles of faulting deformation along the Dead Sea Transform and possible consequences for the recurrence of major earthquakes

    NASA Astrophysics Data System (ADS)

    Janssen, C.; Hoffmann-Rothe, A.; Bohnhoff, M.; Wetzel, H.-U.; Matar, A.; Khatib, M.; Desert Research Group

    2007-08-01

    We compare fault-related deformation of three segments of the major transform plate boundary between Africa and the Arabian plate, the Dead Sea Transform (DST), namely the Arava/Araba fault (Jordan/Israel), the Serghaya fault and the Ghab fault (both Syria). These segments show both similarities and marked differences in faulting deformation and fluid-rock interactions. In the case of the Arava fault, fault damage occurs across a zone up to 300 m wide. A fault core/gouge zone is not exhibited. Along the Serghaya fault, the typical fault zone architecture with a main gouge zone and a damage zone of up to 100 m thickness is exposed. Effects of faulting in the Ghab segment are shown by subsidiary faults and the formation of fault breccias. As in the Arava fault segment, a fault core is not exposed. Fluid-rock interactions are not equally distributed. At the Arava fault segment, the small amount of veins and the lack of alteration and dissolution processes in limestones suggest reduced fluid-rock interactions and limited fluid flow. The fault likely did not act as an important fluid conduit and hydrothermal reactions (cementation, dissolution) did not affect the strength of the fault zone. Contrary to the Arava fault, fluid-assisted fault zone healing processes (i.e. veining and cementation) were active along Serghaya fault and Ghab fault, where fault rock cementation led to porosity reduction and lower permeability. Such low permeability could create domains of higher pore fluid pressure, which reduce the effective shear stress required for slip on the fault. These differences in fluid-rock interactions may have played an important role with respect to the occurrence of earthquakes. We suggest that the recurrence interval on a fault segment that recovers after an earthquake without fluid assisted healing (e.g. Arava fault) should be longer than on segments with strong fluid-assisted healing (cementation; e.g. Serghaya fault, Ghab fault), given that the regional stress

  2. Deep view of the Subduction-Transform Edge Propagator (STEP) fault in the Calabrian Subduction Zone

    NASA Astrophysics Data System (ADS)

    Maesano, Francesco Emanuele; Tiberti, Mara Monica; Basili, Roberto

    2016-04-01

    The Calabrian Subduction Zone plays a key role in the evolution of the central Mediterranean in the framework of the convergence between Africa and Europe. Here, the remnants of the World's oldest oceanic crust form a narrow NW-dipping slab passively subducting beneath the Calabrian Arc. Recently published high-resolution seismic profiles and bathymetric data of the western Ionian Sea highlight the presence of a NNW-SSE faulting system connected with a series of Plio-Pleistocene syn-tectonic basins. These features are correlated with the recent activity of a major NNW-SSE deformation zone confining the active subduction to the SW and interpreted as a Subduction-Transform Edge Propagator (STEP) fault. The goal of this work is to jointly reconstruct the geometry of the STEP fault and the subduction interface in its surroundings. We use multichannel seismic profiles acquired in the southwestern part of the Calabrian accretionary wedge to focus on the STEP fault geometry at depth and to analyse its relationships with shallow deformation features. The quantitative analysis and enhancement of seismic data provided an accurate image of the internal structure of the accretionary wedge at various depths, showing growth strata in the Plio-Pleistocene succession and major discontinuities in the lower crust. Our results depict a main subvertical, slightly east-dipping, lithospheric fault cutting the oceanic crust down to the Moho, and a rich set of associated secondary synthetic and antithetic faults. This picture also provides new insights on the STEP fault propagation mechanism. In addition, the tridimensional correlation of the STEP fault occurrences in various seismic profiles provides a preliminary scheme of its segmentation and highlights the relationships of this master fault with other main structural elements of the Calabrian Arc and Eastern Sicily, including some of the faults deemed to be responsible for major historical earthquakes in the area.

  3. Distinctive diamagnetic fabrics in dolostones evolved at fault cores, the Dead Sea Transform

    NASA Astrophysics Data System (ADS)

    Braun, D.; Weinberger, R.; Eyal, Y.; Feinstein, S.; Harlavan, Y.; Levi, T.

    2015-08-01

    We resolve the anisotropy of magnetic susceptibility (AMS) axes along fault planes, cores and damage zones in rocks that crop out next to the Dead Sea Transform (DST) plate boundary. We measured 261 samples of mainly diamagnetic dolostones that were collected from 15 stations. To test the possible effect of the iron content on the AMS we analyzed the Fe concentrations of the samples in different rock phases. Dolostones with mean magnetic susceptibility value lower than -4 × 10-6 SI and iron content less than ˜1000 ppm are suitable for diamagnetic AMS-based strain analysis. The dolostones along fault planes display AMS fabrics that significantly deviate from the primary "sedimentary fabric". The characteristics of these fabrics include well-grouped, sub-horizontal, minimum principal AMS axes (k3) and sub-vertical magnetic foliations commonly defined by maximum and intermediate principal AMS axes (k1 and k2 axes, respectively). These fabrics are distinctive along fault planes located tens of kilometers apart, with strikes ranging between NNW-SSE and NNE-SSW and different senses of motion. The obtained magnetic foliations (k1-k2) are sub-parallel (within ˜20°) to the fault planes. Based on rock magnetic and geochemical analyses, we interpret the AMS fabrics as the product of both shape and crystallographic anisotropy of the dolostones. Preferred shape alignment evolves due to mechanical rotation of subordinate particles and rock fragments at the fault core. Preferred crystallographic orientation results from elevated frictional heating (>300 °C) during faulting, which enhances c-axes alignment in the cement-supported dolomite breccia due to crystal-plastic processes. The penetrative deformation within fault zones resulted from the local, fault-related strain field and does not reflect the regional strain field. The analyzed AMS fabrics together with fault-plane kinematics provide valuable information on faulting characteristics in the uppermost crust.

  4. Stability and instability in an evolving oceanic transform fault system

    NASA Astrophysics Data System (ADS)

    Forsyth, D. W.; Harmon, N.; Pickle, R. C.; Saal, A.

    2006-12-01

    The Quebrada/Discovery/Gofar fracture zone system at 4 S on the East Pacific Rise currently comprises 9 active en echelon transform traces separated by 8 intratransform spreading centers. A detailed multi-beam bathymetry, side-scan sonar, magnetic and gravity anomaly survey in spring 2006 allows us to reconstruct the history of the transform/ridge geometry over the last 1 million years. Dredging of fresh basaltic glasses and the distribution of transform seismicity helps to unambiguously identify the current spreading centers. Some parts of the system are surprisingly stable; the length and offset between the spreading centers in the Quebrada fracture zone have been nearly constant for more than 700 kyr despite one of the spreading centers being only 5 km long. Other transform traces have died and at least two new ones have started within the last 1 Myr. Rather than being a response to the changing direction of plate motion, the specific changes in geometry seem to be triggered by local changes in volcanic activity. For example, one new spreading center and an associated transform trace began at the site of a rare (in this area), off-axis seamount that may have weakened the lithosphere. Some ridge segments become more "robust" and extend in length, eliminating transforms. The region between the Quebrada and Discovery fracture zones has had a very complex, recent history. The current 30-km-long spreading center has a median valley, unlike typical East Pacific Rise spreading centers. Spreading on that center appears to be slower than average due to an unusual form of overlapping spreading. Although the center is clearly bounded by transforms, at the western end of the Discovery transform, occasional dikes apparently extend north from the Discovery/Gofar spreading center into the adjacent, older seafloor, accommodating some of the spreading that would normally take place on the Quebrada/Discovery center. Overlapping spreading has trapped and rotated crustal blocks

  5. Scaling Relations for the Thermal Structure of Segmented Oceanic Transform Faults

    NASA Astrophysics Data System (ADS)

    Wolfson-Schwehr, M.; Boettcher, M. S.; Behn, M. D.

    2015-12-01

    Mid-ocean ridge-transform faults (RTFs) are a natural laboratory for studying strike-slip earthquake behavior due to their relatively simple geometry, well-constrained slip rates, and quasi-periodic seismic cycles. However, deficiencies in our understanding of the limited size of the largest RTF earthquakes are due, in part, to not considering the effect of short intra-transform spreading centers (ITSCs) on fault thermal structure. We use COMSOL Multiphysics to run a series of 3D finite element simulations of segmented RTFs with visco-plastic rheology. The models test a range of RTF segment lengths (L = 10-150 km), ITSC offset lengths (O = 1-30 km), and spreading rates (V = 2-14 cm/yr). The lithosphere and upper mantle are approximated as steady-state, incompressible flow. Coulomb failure incorporates brittle processes in the lithosphere, and a temperature-dependent flow law for dislocation creep of olivine activates ductile deformation in the mantle. ITSC offsets as small as 2 km affect the thermal structure underlying many segmented RTFs, reducing the area above the 600˚C isotherm, A600, and thus the size of the largest expected earthquakes, Mc. We develop a scaling relation for the critical ITSC offset length, OC, which significantly reduces the thermal affect of adjacent fault segments of length L1 and L2. OC is defined as the ITSC offset that results in an area loss ratio of R = (Aunbroken - Acombined)/Aunbroken - Adecoupled) = 63%, where Aunbroken = C600(L1+L2)1.5V-0.6 is A600 for an RTF of length L1 + L2; Adecoupled = C600(L11.5+L21.5)V-0.6 is the combined A600 of RTFs of lengths L1 and L2, respectively; and Acombined = Aunbroken exp(-O/ OC) + Adecoupled (1-exp(-O/ OC)). C600 is a constant. We use OC and kinematic fault parameters (L1, L2, O, and V) to develop a scaling relation for the approximate seismogenic area, Aseg, for each segment of a RTF system composed of two fault segments. Finally, we estimate the size of Mc on a fault segment based on Aseg. We

  6. Seismo-thermo-mechanical modeling of mature and immature transform faults

    NASA Astrophysics Data System (ADS)

    Preuss, Simon; Gerya, Taras; van Dinther, Ylona

    2016-04-01

    Transform faults (TF) are subdivided into continental and oceanic ones due to their markedly different tectonic position, structure, surface expression, dynamics and seismicity. Both continental and oceanic TFs are zones of rheological weakness, which is a pre-requisite for their existence and long-term stability. Compared to subduction zones, TFs are typically characterized by smaller earthquake magnitudes as both their potential seismogenic width and length are reduced. However, a few very large magnitude (Mw>8) strike-slip events were documented, which are presumably related to the generation of new transform boundaries and/or sudden reactivation of pre-existing fossil structures. In particular, the 11 April 2012 Sumatra Mw 8.6 earthquake is challenging the general concept that such high magnitude events only occur at megathrusts. Hence, the processes of TF nucleation, propagation and their direct relation to the seismic cycle and long-term deformation at both oceanic and continental transforms needs to be investigated jointly to overcome the restricted direct observations in time and space. To gain fundamental understanding of involved physical processes the numerical seismo-thermo-mechanical (STM) modeling approach, validated in a subduction zone setting (Van Dinther et al. 2013), will be adapted for TFs. A simple 2D plane view model geometry using visco-elasto-plastic material behavior will be adopted. We will study and compare seismicity patterns and evolution in two end member TF setups, each with strain-dependent and rate-dependent brittle-plastic weakening processes: (1) A single weak and mature transform fault separating two strong plates (e.g., in between oceanic ridges) and (2) A nucleating or evolving (continental) TF system with disconnected predefined faults within a plate subjected to simple shear deformation (e.g., San Andreas Fault system). The modeling of TFs provides a first tool to establish the STM model approach for transform faults in a

  7. Transforming incomplete fault tree to Ishikawa diagram as an alternative method for technology transfer

    NASA Astrophysics Data System (ADS)

    Batzias, Dimitris F.

    2012-12-01

    Fault Tree Analysis (FTA) can be used for technology transfer when the relevant problem (called 'top even' in FTA) is solved in a technology centre and the results are diffused to interested parties (usually Small Medium Enterprises - SMEs) that have not the proper equipment and the required know-how to solve the problem by their own. Nevertheless, there is a significant drawback in this procedure: the information usually provided by the SMEs to the technology centre, about production conditions and corresponding quality characteristics of the product, and (sometimes) the relevant expertise in the Knowledge Base of this centre may be inadequate to form a complete fault tree. Since such cases are quite frequent in practice, we have developed a methodology for transforming incomplete fault tree to Ishikawa diagram, which is more flexible and less strict in establishing causal chains, because it uses a surface phenomenological level with a limited number of categories of faults. On the other hand, such an Ishikawa diagram can be extended to simulate a fault tree as relevant knowledge increases. An implementation of this transformation, referring to anodization of aluminium, is presented.

  8. Gravity field over the Sea of Galilee: Evidence for a composite basin along a transform fault

    USGS Publications Warehouse

    Ben-Avraham, Z.; ten Brink, U.; Bell, R.; Reznikov, M.

    1996-01-01

    The Sea of Galilee (Lake Kinneret) is located at the northern portion of the Kinneret-Bet Shean basin, in the northern Dead Sea transform. Three hundred kilometers of continuous marine gravity data were collected in the lake and integrated with land gravity data to a distance of more than 20 km around the lake. Analyses of the gravity data resulted in a free-air anomaly map, a variable density Bouguer anomaly map, and a horizontal first derivative map of the Bouguer anomaly. These maps, together with gravity models of profiles across the lake and the area south of it, were used to infer the geometry of the basins in this region and the main faults of the transform system. The Sea of Galilee can be divided into two units. The southern half is a pull-apart that extends to the Kinarot Valley, south of the lake, whereas the northern half was formed by rotational opening and transverse normal faults. The deepest part of the basinal area is located well south of the deepest bathymetric depression. This implies that the northeastern part of the lake, where the bathymetry is the deepest, is a young feature that is actively subsiding now. The pull-apart basin is almost symmetrical in the southern part of the lake and in the Kinarot Valley south of the lake. This suggests that the basin here is bounded by strike-slip faults on both sides. The eastern boundary fault extends to the northern part of the lake, while the western fault does not cross the northern part. The main factor controlling the structural complexity of this area is the interaction of the Dead Sea transform with a subperpendicular fault system and rotated blocks.

  9. Thermal-mechanical behavior of oceanic transform faults: Implications for the spatial distribution of seismicity

    NASA Astrophysics Data System (ADS)

    Roland, Emily; Behn, Mark D.; Hirth, Greg

    2010-07-01

    To investigate the spatial distribution of earthquakes along oceanic transform faults, we utilize a 3-D finite element model to calculate the mantle flow field and temperature structure associated with a ridge-transform-ridge system. The model incorporates a viscoplastic rheology to simulate brittle failure in the lithosphere and a non-Newtonian temperature-dependent viscous flow law in the underlying mantle. We consider the effects of three key thermal and rheological feedbacks: (1) frictional weakening due to mantle alteration, (2) shear heating, and (3) hydrothermal circulation in the shallow lithosphere. Of these effects, the thermal structure is most strongly influenced by hydrothermal cooling. We quantify the thermally controlled seismogenic area for a range of fault parameters, including slip rate and fault length, and find that the area between the 350°C and 600°C isotherms (analogous to the zone of seismic slip) is nearly identical to that predicted from a half-space cooling model. However, in contrast to the half-space cooling model, we find that the depth to the 600°C isotherm and the width of the seismogenic zone are nearly constant along the fault, consistent with seismic observations. The calculated temperature structure and zone of permeable fluid flow are also used to approximate the stability field of hydrous phases in the upper mantle. We find that for slow slipping faults, the potential zone of hydrous alteration extends greater than 10 km in depth, suggesting that transform faults serve as a significant pathway for water to enter the oceanic upper mantle.

  10. Automatic fault feature extraction of mechanical anomaly on induction motor bearing using ensemble super-wavelet transform

    NASA Astrophysics Data System (ADS)

    He, Wangpeng; Zi, Yanyang; Chen, Binqiang; Wu, Feng; He, Zhengjia

    2015-03-01

    Mechanical anomaly is a major failure type of induction motor. It is of great value to detect the resulting fault feature automatically. In this paper, an ensemble super-wavelet transform (ESW) is proposed for investigating vibration features of motor bearing faults. The ESW is put forward based on the combination of tunable Q-factor wavelet transform (TQWT) and Hilbert transform such that fault feature adaptability is enabled. Within ESW, a parametric optimization is performed on the measured signal to obtain a quality TQWT basis that best demonstrate the hidden fault feature. TQWT is introduced as it provides a vast wavelet dictionary with time-frequency localization ability. The parametric optimization is guided according to the maximization of fault feature ratio, which is a new quantitative measure of periodic fault signatures. The fault feature ratio is derived from the digital Hilbert demodulation analysis with an insightful quantitative interpretation. The output of ESW on the measured signal is a selected wavelet scale with indicated fault features. It is verified via numerical simulations that ESW can match the oscillatory behavior of signals without artificially specified. The proposed method is applied to two engineering cases, signals of which were collected from wind turbine and steel temper mill, to verify its effectiveness. The processed results demonstrate that the proposed method is more effective in extracting weak fault features of induction motor bearings compared with Fourier transform, direct Hilbert envelope spectrum, different wavelet transforms and spectral kurtosis.

  11. Temporal and spatial variations in seismicity of fast-slipping oceanic transform faults at the East Pacific Rise

    NASA Astrophysics Data System (ADS)

    Zhong, Q.; Lin, J.; Zheng, T.

    2015-12-01

    We analyzed hydro-acoustically recorded seismicity data from the East Pacific Rise (EPR) to investigate the temporal and spatial variations in seismicity of fast-slipping oceanic transform faults. The hydrophones in the Pacific ocean have recorded earthquakes along the EPR from May 1996 to April 2002. Our investigation focused on four transform faults: Wilkes, Siqueiros, Gofar and Clipperton. Our analysis revealed that all of the four transform faults are associated with numerous foreshocks or/and aftershocks of mainshocks with magnitude M ~ 5 or greater. And the seismicity on the fault present segmented state on the fault or on the hook between transform fault and the ridge. First we fit the aftershocks time durations of more than 100 mainshocks with magnitude M > 4.5. Results of the analyses revealed the following: (1) The aftershock duration ta of the investigated mainshocks ranges from about 5.5 days to about 3.1 years。The seismicity rate immediately following a mainshock event, R0, varies from about 10 to 511, corresponding to average error of 10.7 % and the maximum error of 33.3 %, respectively. In addition, we calculate the rate between background seismicity, r, at each fault segment. Results revealed that the logarithm of R0/r correlate with logarithm time duration of aftershocks but with almost no relation to the mainshock magnitude. We also calculated the energy accumulation of earthquakes on each segment of the transform faults. The cumulated energy differed from each other: Earthquake energy released in the last 6 years (from 1996 to 2002) are valuated at from 1.7×1019 N•m/km on the Siqueiros Transform Fault, to 2.2×1017 N•m/km on the Clipperton. Segments on each fault are calculated to have similar energy release. Together these investigations helped to advance our understanding of the earthquake mechanism and geodynamics of fast-slipping oceanic transform faults.

  12. Mantle uplift and exhumation caused by long-lived transpression at a major transform fault

    NASA Astrophysics Data System (ADS)

    Maia, M.; Sichel, S. E.; Briais, A.; Brunelli, D.; Ferreira, N.; Ligi, M.; Campos, T.; Mougel, B.; Hemond, C.

    2015-12-01

    Large portions of slow-spreading ridges have mantle-derived peridotites emplaced either on, or at shallow levels below the sea floor. Mantle and deep rock exposure in such contexts is often linked to extensional tectonics through low-angle detachment faults at oceanic core complexes or, along transform faults, to transtension due to small changes in spreading geometry. At the large-offset St. Paul transform system, in the Equatorial Atlantic, a large body of ultramafic rocks forms the archipelago of St. Peter & St. Paul. These islets, emplaced near the axis of the Mid-Atlantic ridge, have intrigued geologists since Darwin's time. They are made of variably serpentinized and mylonitized peridotites and the continuous uplift rate of 1.5 mm/yr reveals that they are presently under tectonic deformation. The existence of an abnormally cold upper mantle or cold lithosphere in the Equatorial Atlantic was, until now, the preferred explanation for the origin of these ultramafics. High-resolution geophysical data and rock samples acquired in the St. Paul transform system in 2013 show that the origin of the St. Peter & St. Paul archipelago is linked to compressive stresses along the large-offset transform fault. The islets are the summit of a large push-up ridge formed by deformed mantle located in the center of a positive flower structure, where large portions of mylonitized mantle are uplifted. The transpressive stress field can be explained by the propagation of the northern Mid-Atlantic Ridge (MAR) segment into the transform domain, which induced the migration and segmentation of the transform fault creating a series of restraining step-overs. A counterclockwise change in plate motion at ~11 Ma initially generated extensive stresses in the transform domain, forming a flexural transverse ridge, as observed in other transform faults. Shortly after the plate reorganization, the MAR segment started to propagate southwards, adapting to the new spreading direction. Enhanced melt

  13. Foreshock Sequences and Short-Term Earthquake Predictability on East Pacific Rise Transform Faults

    NASA Astrophysics Data System (ADS)

    McGuire, J. J.; Boettcher, M. S.; Jordan, T. H.

    2004-12-01

    A predominant view of continental seismicity postulates that all earthquakes initiate in a similar manner regardless of their eventual size and that earthquake triggering can be described by an Endemic Type Aftershock Sequence (ETAS) model [e.g. Ogata, 1988, Helmstetter and Sorenette 2002]. These null hypotheses cannot be rejected as an explanation for the relative abundances of foreshocks and aftershocks to large earthquakes in California [Helmstetter et al., 2003]. An alternative location for testing this hypothesis is mid-ocean ridge transform faults (RTFs), which have many properties that are distinct from continental transform faults: most plate motion is accommodated aseismically, many large earthquakes are slow events enriched in low-frequency radiation, and the seismicity shows depleted aftershock sequences and high foreshock activity. Here we use the 1996-2001 NOAA-PMEL hydroacoustic seismicity catalog for equatorial East Pacific Rise transform faults to show that the foreshock/aftershock ratio is two orders of magnitude greater than the ETAS prediction based on global RTF aftershock abundances. We can thus reject the null hypothesis that there is no fundamental distinction between foreshocks, mainshocks, and aftershocks on RTFs. We further demonstrate (retrospectively) that foreshock sequences on East Pacific Rise transform faults can be used to achieve statistically significant short-term prediction of large earthquakes (magnitude ≥ 5.4) with good spatial (15-km) and temporal (1-hr) resolution using the NOAA-PMEL catalogs. Our very simplistic approach produces a large number of false alarms, but it successfully predicts the majority (70%) of M≥5.4 earthquakes while covering only a tiny fraction (0.15%) of the total potential space-time volume with alarms. Therefore, it achieves a large probability gain (about a factor of 500) over random guessing, despite not using any near field data. The predictability of large EPR transform earthquakes suggests

  14. Is the Troodos ophiolite (Cyprus) a complete, transform fault-bounded Neotethyan ridge segment?

    NASA Astrophysics Data System (ADS)

    Morris, Antony; Maffione, Marco

    2016-04-01

    We report new paleomagnetic data from the sheeted dike complex of the Troodos ophiolite (Cyprus) that indicate a hitherto unrecognized oceanic transform fault system marks its northern limit. The style, magnitude and scale of upper crustal fault block rotations in the northwestern Troodos region mirror those observed adjacent to the well-known Southern Troodos Transform Fault Zone along the southern edge of the ophiolite. A pattern of increasing clockwise rotation toward the north, coupled with consistent original dike strikes and inclined net rotation axes across this region, is compatible with distributed deformation adjacent to a dextrally-slipping transform system with a principal displacement zone just to the north of the exposed ophiolite. Combined with existing constraints on the spreading fabric, this implies segmentation of the Troodos ridge system on length scales of ~40 km, and suggests that a coherent strip of Neotethyan lithosphere, bounded by transforms and containing a complete ridge segment, has been uplifted to form the currently exposed Troodos ophiolite. Moreover, the inferred length scale of the ridge segment is consistent with formation at a slow-spreading rate during Tethyan seafloor spreading and with a supra-subduction zone environment, as indicated by geochemical constraints.

  15. Along Strike Heterogeneity of Seismic Slip Revealed by Oceanic Transform Fault Earthquakes

    NASA Astrophysics Data System (ADS)

    Aderhold, K.; Abercrombie, R. E.

    2015-12-01

    Oceanic transform faults (OTFs) are considered to have relatively simple structure [thermal, geometric, compositional], with the brittle-ductile transition defined by the 600-800ºC isotherm. Earthquakes on these faults account for less than half of the expected slip (Boettcher & Jordan, 2004), leaving the majority of motion to be accommodated aseismically. The 2015 MW7.1 Charlie-Gibbs transform earthquake is the latest of seven large [M≥6.25] earthquakes that form two quasi-repeating sequences dating back to 1920. These two sequences are separated by a region of persistent aseismicity in the center of the transform, interpreted to be a rupture barrier that prevents the full extent of the transform from rupturing in a single earthquake. However, aseismic rupture barriers alone cannot account for the inferred deficit in the seismic budget of OTFs. A growing catalogue of slip distributions has revealed distinctive behavior for large OTF earthquakes. We present evidence from teleseismic body wave modeling for directivity and slip distribution of four MW ≥ 7.0 oceanic strike-slip earthquakes: the 2015 MW7.1 Charlie-Gibbs transform earthquake in the North Atlantic, the 2015 MW7.0 Fourier transform earthquake in the South Atlantic, and the 2013 MW7.3 and 2006 MW7.4 South Sandwich transform earthquakes in the Southern Ocean. Each earthquake initiates near the ridge with nominal slip then propagates unilaterally to rupture larger asperities nearer the middle of the transform, similar to behavior observed for the 1994 MW7.0 Romanche transform earthquake. Significant continental strike-slip earthquakes, such as the 2002 MW7.9 Denali earthquake and the 2001 MW7.8 Kunlun earthquake, also exhibit unilateral ruptures with a small initial slip. The slip distributions of large oceanic transform earthquakes suggest that seismic coupling of OTFs varies considerably along strike, with large slip asperities separated by areas of little or no slip. Substantial earthquakes are not

  16. Imaging along-strike variations in mechanical properties of the Gofar transform fault, East Pacific Rise

    NASA Astrophysics Data System (ADS)

    Froment, B.; McGuire, J. J.; Hilst, R. D.; Gouédard, P.; Roland, E. C.; Zhang, H.; Collins, J. A.

    2014-09-01

    A large part of global plate motion on mid-ocean ridge transform faults (RTFs) is not accommodated as major earthquakes. When large earthquakes do occur, they often repeat quasiperiodically. We focus here on the high slip rate (˜14 cm/yr) Gofar transform fault on the equatorial East Pacific Rise. This fault is subdivided into patches that slip during Mw 5.5-6 earthquakes every 5 to 6 years. These patches are separated by rupture barriers that accommodate slip through swarms of smaller events and/or aseismic creep. We performed an imaging study to investigate which spatiotemporal variations of the fault zone properties control this segmentation in mechanical behavior and could explain the specific behavior of RTFs at the global scale. We adopt a double-difference approach in a joint inversion of active air gun shots and microseismicity recorded for 1 year. This data set includes the 2008 Mw 6 Gofar earthquake. The along-strike P wave velocity structure reveals an abrupt transition between the barrier area, characterized by a damaged fault zone of 10-20% reduced Vp and a nearly intact fault zone in the asperity area. The importance of the strength of the damage zone on the mechanical behavior is supported by the temporal S wave velocity changes which suggest increased damage within the barrier area, during the week preceding the Mw 6 earthquake. Our results support the conclusion that extended highly damaged zones are the key factor in limiting the role of major earthquakes to accommodate plate motion along RTFs.

  17. Anatomy of landslides along the Dead Sea Transform Fault System in NW Jordan

    NASA Astrophysics Data System (ADS)

    Dill, H. G.; Hahne, K.; Shaqour, F.

    2012-03-01

    In the mountainous region north of Amman, Jordan, Cenomanian calcareous rocks are being monitored constantly for their mass wasting processes which occasionally cause severe damage to the Amman-Irbid Highway. Satellite remote sensing data (Landsat TM, ASTER, and SRTM) and ground measurements are applied to investigate the anatomy of landslides along the Dead Sea Transform Fault System (DSTFS), a prominent strike-slip fault. The joints and faults pertinent to the DSTFS match the architectural elements identified in landslides of different size. This similarity attests to a close genetic relation between the tectonic setting of one of the most prominent fault zones on the earth and modern geomorphologic processes. Six indicators stand out in particular: 1) The fractures developing in N-S and splay faults represent the N-S lateral movement of the DSTFS. They governed the position of the landslides. 2) Cracks and faults aligned in NE-SW to NNW-SSW were caused by compressional strength. They were subsequently reactivated during extensional processes and used in some cases as slip planes during mass wasting. 3) Minor landslides with NE-SW straight scarps were derived from compressional features which were turned into slip planes during the incipient stages of mass wasting. They occur mainly along the slopes in small wadis or where a wide wadi narrows upstream. 4) Major landslides with curved instead of straight scarps and rotational slides are representative of a more advanced level of mass wasting. These areas have to be marked in the maps and during land management projects as high-risk area mainly and may be encountered in large wadis with steep slopes or longitudinal slopes undercut by road construction works. 5) The spatial relation between minor faults and slope angle is crucial as to the vulnerability of the areas in terms of mass wasting. 6) Springs lined up along faults cause serious problems to engineering geology in that they step up the behavior of marly

  18. Late Pleistocene and Holocene slip rate of the Northern Wadi Araba fault, Dead Sea Transform, Jordan

    NASA Astrophysics Data System (ADS)

    Niemi, Tina M.; Zhang, Hongwei; Atallah, Mohammad; Harrison, Bruce J.

    The Wadi Araba Valley is a morphotectonic depression along part of theDead Sea Transform (DST) plate boundary that separates the Arabian plateon the east from the Sinai subplate on the west. The Wadi Araba fault(WAF) is the main strike-slip faults one of between the Gulf of Aqaba and the E-Wtrending Khunayzira (Amatzayahu) fault that bounds the southern end ofthe Dead Sea. Just south of the Dead Sea, the WAF cuts across severalgenerations of alluvial fans that formed on tributaries to the Wadi Dahalafter the regression of Late Pleistocene Lake Lisan ca. 15 ka. Geomorphicand stratigraphic evidence of active faulting, including left-laterally offsetstream channels and alluvial-fan surfaces, yielded fault slip-rate data for thenorthern segment of WAF. Typical cumulative displacements of 54 m,39 m, and 22.5 m of stream channels and alluvial-fan surfaces acrossthe fault were measured from detailed geologic and topographic mapping.The 54 m offset of the oldest alluvial-fan surface (Q f1 ) occurredafter the final lowering of Lake Lisan (16-15 ka) and before 11 ka yieldinga slip-rate range of 3.4 mm/yr to 4.9 mm/yr. Based on radiocarbonages of charcoal and landsnail shell samples from the buried Q f2 alluvial-fan deposits exposed in trenches excavated across the fault, the39 m and 22.5 m offsets occurred after 9 ka and 5.8 ka, respectively. These data yield a slip-rate range between 3.9 mm/yr and 6.0 mm/yr.The small variability in these slip-rate estimates for different time periodssuggests that the northern Wadi Araba fault has maintained a relativelyconstant slip rate in the past 15 ka. We calculate an average slip rate of 4.7± 1.3 mm/yr since 15 ka based on the three separate displacementsand age estimates. Five separate offsets of 3 m were measured from gullybends and the offset of small fault-scarp alluvial fans. These displacementdata suggest a coseismic slip of 3 m in the last earthquake, or acumulative slip of 3 m in the past few earthquakes. A maximum slip of3 m

  19. Analysis of pseudocolor transformations of ERTS-1 images of Southern California area. [geological faults and lineaments

    NASA Technical Reports Server (NTRS)

    Merifield, P. M. (Principal Investigator); Lamar, D. L.; Stratton, R. H.; Lamar, J. V.; Gazley, C., Jr.

    1974-01-01

    The author has identified the following significant results. Representative faults and lineaments, natural features on the Mojave Desert, and cultural features of the southern California area were studied on ERTS-1 images. The relative appearances of the features were compared on a band 4 and 5 subtraction image, its pseudocolor transformation, and pseudocolor images of bands 4, 5, and 7. Selected features were also evaluated in a test given students at the University of California, Los Angeles. Observations and the test revealed no significant improvement in the ability to detect and locate faults and lineaments on the pseudocolor transformations. With the exception of dry lake surfaces, no enhancement of the features studied was observed on the bands 4 and 5 subtraction images. Geologic and geographic features characterized by minor tonal differences on relatively flat surfaces were enhanced on some of the pseudocolor images.

  20. [Application of optimized parameters SVM based on photoacoustic spectroscopy method in fault diagnosis of power transformer].

    PubMed

    Zhang, Yu-xin; Cheng, Zhi-feng; Xu, Zheng-ping; Bai, Jing

    2015-01-01

    In order to solve the problems such as complex operation, consumption for the carrier gas and long test period in traditional power transformer fault diagnosis approach based on dissolved gas analysis (DGA), this paper proposes a new method which is detecting 5 types of characteristic gas content in transformer oil such as CH4, C2H2, C2H4, C2H6 and H2 based on photoacoustic Spectroscopy and C2H2/C2H4, CH4/H2, C2H4/C2H6 three-ratios data are calculated. The support vector machine model was constructed using cross validation method under five support vector machine functions and four kernel functions, heuristic algorithms were used in parameter optimization for penalty factor c and g, which to establish the best SVM model for the highest fault diagnosis accuracy and the fast computing speed. Particles swarm optimization and genetic algorithm two types of heuristic algorithms were comparative studied in this paper for accuracy and speed in optimization. The simulation result shows that SVM model composed of C-SVC, RBF kernel functions and genetic algorithm obtain 97. 5% accuracy in test sample set and 98. 333 3% accuracy in train sample set, and genetic algorithm was about two times faster than particles swarm optimization in computing speed. The methods described in this paper has many advantages such as simple operation, non-contact measurement, no consumption for the carrier gas, long test period, high stability and sensitivity, the result shows that the methods described in this paper can instead of the traditional transformer fault diagnosis by gas chromatography and meets the actual project needs in transformer fault diagnosis.

  1. Aqaba-Levant transform-related faults in the Gulf of Suez rift: The Durba-Araba fault, Sinai Peninsula, Egypt

    NASA Astrophysics Data System (ADS)

    Abdeen, Mamdouh M.; Abdelmaksoud, Ashraf S.

    2014-09-01

    The Gulf of Suez rift is dominated by NNW- to NW-striking “Clysmic” faults trending parallel to the rift. In addition there are NNE- and WNW-striking (oblique) faults that trend at an angle to the rift. The Durba-Araba fault (DAF) in southwestern Sinai represents one of several NNE-striking faults. It separates the Durba fault block on its NW from the Araba fault block on its SE. Detailed (1:20,000 scale) field mapping and structural studies of the DAF and the onshore area to the east of Belayim Bay (eastern margin of the central Gulf of Suez rift), indicate that the exposed part of the DAF extends for 7.5 km NNE from the mouth of Wadi Araba, at which point it bends and splays into three N- to NNW striking faults, forming a horse tail structure. The fault shows 4 km of pure sinistral strike-slip displacement. Northerly plunging fault propagation folds in the Phanerozoic rocks adjacent to the DAF accommodated the sinistral displacement. These folds are cut and displaced by the splay faults. Near its northern end, the middle splay fault affects the Pliocene El Qa'a Formation. At Gebel Qabeliat a group of en echelon left-stepping NNE- to N-striking faults overlaps the DAF generating a pull-apart (rhomb) graben, in which Pliocene and Quaternary sediments are downthrown against the Upper Miocene rocks. Kinematic indicators on most of these faults show major sinistral strike-slip movement. Palaeostress analysis of slip striae indicates sub-horizontal ENE to NNE extension, comparable to the present day stress regime. Cross-cutting relationships indicate that the NNE- to N-striking oblique faults are younger than the NW-striking Clysmic faults. These faults are probably presently active since they affect Pliocene and Quaternary sediments. It is proposed that these faults are related to the Aqaba-Levant transform that has been active since the Middle Miocene.

  2. Earthquake source mechanisms and transform fault tectonics in the Gulf of California

    NASA Technical Reports Server (NTRS)

    Goff, John A.; Bergman, Eric A.; Solomon, Sean C.

    1987-01-01

    The source parameters of 19 large earthquakes in the Gulf of California were determined from inversions of long-period P and SH waveforms. The goal was to understand the recent slip history of this dominantly transform boundary between the Pacific and North American plates as well as the effect on earthquake characteristics of the transition from young oceanic to continental lithosphere. For the better recorded transform events, the fault strike is resolved to + or - 4 deg at 90 percent confidence. The slip vectors thus provide important constraints on the direction of relative plate motion. Most centroid depths are poorly resolved because of tradeoffs between depth and source time function. On the basis of waveform modeling, historical seismicity, and other factors, it is appropriate to divide the Gulf into three distinct zones. The difference in seismic character among the three zones is likely the result of differing levels of maturity of the processes of rifting, generation of oceanic crust, and formation of stable oceanic transform faults. The mechanism of an earthquake on the Tres Marias Escarpment is characterized by thrust faulting and likely indicates the direction of relative motion between the Rivera and North American plates. This mechanism requires revision in plate velocity models which predict strike slip motion at this location.

  3. Boundary-layer mantle flow under the Dead Sea transform fault inferred from seismic anisotropy.

    PubMed

    Rümpker, Georg; Ryberg, Trond; Bock, Günter

    2003-10-01

    Lithospheric-scale transform faults play an important role in the dynamics of global plate motion. Near-surface deformation fields for such faults are relatively well documented by satellite geodesy, strain measurements and earthquake source studies, and deeper crustal structure has been imaged by seismic profiling. Relatively little is known, however, about deformation taking place in the subcrustal lithosphere--that is, the width and depth of the region associated with the deformation, the transition between deformed and undeformed lithosphere and the interaction between lithospheric and asthenospheric mantle flow at the plate boundary. Here we present evidence for a narrow, approximately 20-km-wide, subcrustal anisotropic zone of fault-parallel mineral alignment beneath the Dead Sea transform, obtained from an inversion of shear-wave splitting observations along a dense receiver profile. The geometry of this zone and the contrast between distinct anisotropic domains suggest subhorizontal mantle flow within a vertical boundary layer that extends through the entire lithosphere and accommodates the transform motion between the African and Arabian plates within this relatively narrow zone.

  4. Structural transformations of stacking fault tetrahedra upon the absorption of point defects

    NASA Astrophysics Data System (ADS)

    Poletaev, G. M.; Starostenkov, M. D.

    2009-01-01

    Mechanisms of the structural modification of stacking fault tetrahedra (SFTs) upon the absorption of point defects have been studied by the method of molecular dynamics. The sequential absorption of vacancies by a perfect SFT is accompanied by the following transformations: (i) the formation of a step on one of the SFT faces, (ii) a change in the step sign upon reaching the middle of the face, (iii) the formation of an SFT with truncated vertex, and (iv) the formation of the perfect SFT. Upon the absorption of interstitial atoms, the stages of SFT transformation follow the reverse order.

  5. Incipient fault diagnosis of power transformers using optical spectro-photometric technique

    NASA Astrophysics Data System (ADS)

    Hussain, K.; Karmakar, Subrata

    2015-06-01

    Power transformers are the vital equipment in the network of power generation, transmission and distribution. Mineral oil in oil-filled transformers plays very important role as far as electrical insulation for the winding and cooling of the transformer is concerned. As transformers are always under the influence of electrical and thermal stresses, incipient faults like partial discharge, sparking and arcing take place. As a result, mineral oil deteriorates there by premature failure of the transformer occurs causing huge losses in terms of revenue and assets. Therefore, the transformer health condition has to be monitored continuously. The Dissolved Gas Analysis (DGA) is being extensively used for this purpose, but it has some drawbacks like it needs carrier gas, regular instrument calibration, etc. To overcome these drawbacks, Ultraviolet (UV) -Visible and Fourier Transform Infrared (FTIR) Spectro-photometric techniques are used as diagnostic tools for investigating the degraded transformer oil affected by electrical, mechanical and thermal stresses. The technique has several advantages over the conventional DGA technique.

  6. Morphotectonic fabric of the Orozco Transform Fault: Results From a Sea Beam investigation

    NASA Astrophysics Data System (ADS)

    Madsen, John A.; Fox, Paul J.; MacDonald, Ken C.

    1986-03-01

    We have used data collected with the Sea Beam system to produce a detailed regional bathymetric map of the medium to fast slipping (90 mm/yr) Orozco Transform Fault. The morphotectonic fabric of the 90 × 50 km transform domain is spatially heterogeneous and is composed of relatively shallow areas (<2800 m) bounded by E-W and N-S trending troughs and basins (>3200 m). The plate boundary geometry is clearly identified morphologically and is characterized by a series of linked basins and troughs that approximate a zed pattern in plan view. East-west trending basins define the northern and southern boundaries of the transform domain, and these troughs are thought to mark the location of strike-slip tectonism. A central, north-south trending ridge with an axial valley, called here the Mid-Orozco spreading center, is thought to represent a short (30 km) ridge segment that links two transform faults. Morphotectonic relationships developed along the southeastern flank of the survey area suggest that this plate boundary geometry has recently become unstable and is presently undergoing a transformation as the tip of the East Pacific Rise axis propagates northward across the transform domain bypassing the Mid-Orozco spreading center. If the southern ridge axis continues to propagate northward it will link with the aseismic extension of the northern strike-slip strand and the present-day plate boundary will evolve into a simple ridge-transform-ridge (R-T-R) geometry with an offset of approximately 70 km.

  7. Two Stage Helical Gearbox Fault Detection and Diagnosis based on Continuous Wavelet Transformation of Time Synchronous Averaged Vibration Signals

    NASA Astrophysics Data System (ADS)

    Elbarghathi, F.; Wang, T.; Zhen, D.; Gu, F.; Ball, A.

    2012-05-01

    Vibration signals from a gearbox are usually very noisy which makes it difficult to find reliable symptoms of a fault in a multistage gearbox. This paper explores the use of time synchronous average (TSA) to suppress the noise and Continue Wavelet Transformation (CWT) to enhance the non-stationary nature of fault signal for more accurate fault diagnosis. The results obtained in diagnosis an incipient gear breakage show that fault diagnosis results can be improved by using an appropriate wavelet. Moreover, a new scheme based on the level of wavelet coefficient amplitudes of baseline data alone, without faulty data samples, is suggested to select an optimal wavelet.

  8. Wavelet transform based on inner product in fault diagnosis of rotating machinery: A review

    NASA Astrophysics Data System (ADS)

    Chen, Jinglong; Li, Zipeng; Pan, Jun; Chen, Gaige; Zi, Yanyang; Yuan, Jing; Chen, Binqiang; He, Zhengjia

    2016-03-01

    As a significant role in industrial equipment, rotating machinery fault diagnosis (RMFD) always draws lots of attention for guaranteeing product quality and improving economic benefit. But non-stationary vibration signal with a large amount of noise on abnormal condition of weak fault or compound fault in many cases would lead to this task challenging. As one of the most powerful non-stationary signal processing techniques, wavelet transform (WT) has been extensively studied and widely applied in RMFD. Numerous publications about the study and applications of WT for RMFD have been presented to academic journals, technical reports and conference proceedings. Many previous publications admit that WT can be realized by means of inner product principle of signal and wavelet base. This paper verifies the essence on inner product operation of WT by simulation and field experiments. Then the development process of WT based on inner product is concluded and the applications of major developments in RMFD are also summarized. Finally, super wavelet transform as an important prospect of WT based on inner product are presented and discussed. It is expected that this paper can offer an in-depth and comprehensive references for researchers and help them with finding out further research topics.

  9. Hydroacoustic seismicity along oceanic transform faults: Contrasts between the East Pacific Rise and Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Zheng, T.; Lin, J.; Zhong, Q.

    2015-12-01

    We investigate the characteristics of seismicity of oceanic transform faults through analyzing hydroacoustic data recorded along the fast-spreading East Pacific Rise (EPR) and slow-spreading Mid-Atlantic Ridge (MAR), respectively. The investigated region on the EPR is within 15°S-15°N from the Garrett to Clipperton Transform Fault during time period of June 1996 to September 2002. Meanwhile, the investigated region on the MAR is within 15°-37°N from the Fifteen-Twenty to Oceanographer Transform Fault during time period of February 1999 to August 2003. Using space-time correlation analysis, we matched hydroacoustic events with earthquakes from the Global Centroid Moment Tensor (GCMT) solutions for event magnitude greater than 4.8. Our analyses revealed systematic differences in the seismicity characteristics between the EPR and MAR: (1) Along the EPR, more than ninety percent of seismicity occurred within several kilometers from transform faults, a few percent occurred near over-lapping spreading centers, while the rest occurred along the ridge axis. Along the MAR, hydroacoustic seismicity is much more scattered near the ridge axis, transform faults, and non-transform offsets. (2) Near the EPR transform faults, the standard deviation of the separation distance of the hydroacoustic events from the morphologically-determined transform fault axis is s = 5.7 km. In contrast, the separation distance of hydroacoustic events to the transform faults is greater (s = 11.9 km), reflecting possibly more complex acoustic scattering due to complex MAR topography as well as more complex tectonic activity. (3) The mean hydroacoustic magnitude of the investigated EPR events is 3.3 (s = 0.6), while the mean hydroacoustic magnitude of the studied MAR events is 3.0 (s = 0.7). The mean hydroacoustic seismicity rate is 2.1 events per year per km of the EPR transform fault length, comparing to the mean seismicity rate of 0.5 events per year per km of the MAR transform fault length. (4

  10. Oceanic Transform Fault-Zone Geomorphology in the Gulf of California from High-Resolution Bathymetric Data

    NASA Astrophysics Data System (ADS)

    Hilley, G. E.; Aron, F.; Baden, C. W.; Castillo, C. M.; Johnstone, S. A.; Nevitt, J. M.; McHargue, T.; Paull, C. K.; Sare, R.; Shumaker, L.; Young, H.

    2015-12-01

    We use high-resolution, deep-water bathymetry to examine the structure of, and offset along, transform faults in the Gulf of California. These data provide detailed observations of fault-zone geomorphology of an active transform fault hosted in an area transitioning from continental to oceanic crust. Bathymetric data were collected by an autonomous underwater vehicle deployed by the Monterey Bay Aquarium Research Institute in 2012. Dense ocean-bottom point clouds allowed construction of an ~1-m-resolution digital terrain model, which provides comparable spatial resolution to early airborne laser swath mapping surveys. The data reveal a set of complex, multi-stranded fault zones, whose morphologies suggest a temporal migration of deformation between individual strands contained within an up to 1 km wide zone, similar to complex fault zones observed within continental crust in subaerial environments. Individual fault strands show restraining steps that create positive relief along the ocean floor in their vicinity. Although the depositional nature of these deep-water systems makes identification of offset features challenging, we found a series of offset fans along a fault strand with consistent right-lateral offsets of 17-21 m. These are likely multi-event offsets, given the length of the transform segments and magnitudes of historically recorded earthquakes in the region. The consistency of these multi-event offsets suggests that an external process predating the displacement of the fans, such as seismic shaking due to large earthquakes, may be responsible for the synchroneity of these features. Our study demonstrates that the fault-zone geomorphology of oceanic transform faults in the Gulf of California bears resemblance to that of terrestrial strike-slip faults hosted in continental crust, and that high-resolution, deep water bathymetry can provide information about the earthquake history of these environments.

  11. Numerical Methods for the Analysis of Power Transformer Tank Deformation and Rupture Due to Internal Arcing Faults.

    PubMed

    Yan, Chenguang; Hao, Zhiguo; Zhang, Song; Zhang, Baohui; Zheng, Tao

    2015-01-01

    Power transformer rupture and fire resulting from an arcing fault inside the tank usually leads to significant security risks and serious economic loss. In order to reveal the essence of tank deformation or explosion, this paper presents a 3-D numerical computational tool to simulate the structural dynamic behavior due to overpressure inside transformer tank. To illustrate the effectiveness of the proposed method, a 17.3 MJ and a 6.3 MJ arcing fault were simulated on a real full-scale 360MVA/220kV oil-immersed transformer model, respectively. By employing the finite element method, the transformer internal overpressure distribution, wave propagation and von-Mises stress were solved. The numerical results indicate that the increase of pressure and mechanical stress distribution are non-uniform and the stress tends to concentrate on connecting parts of the tank as the fault time evolves. Given this feature, it becomes possible to reduce the risk of transformer tank rupture through limiting the fault energy and enhancing the mechanical strength of the local stress concentrative areas. The theoretical model and numerical simulation method proposed in this paper can be used as a substitute for risky and costly field tests in fault overpressure analysis and tank mitigation design of transformers.

  12. Numerical Methods for the Analysis of Power Transformer Tank Deformation and Rupture Due to Internal Arcing Faults

    PubMed Central

    Yan, Chenguang; Hao, Zhiguo; Zhang, Song; Zhang, Baohui; Zheng, Tao

    2015-01-01

    Power transformer rupture and fire resulting from an arcing fault inside the tank usually leads to significant security risks and serious economic loss. In order to reveal the essence of tank deformation or explosion, this paper presents a 3-D numerical computational tool to simulate the structural dynamic behavior due to overpressure inside transformer tank. To illustrate the effectiveness of the proposed method, a 17.3MJ and a 6.3MJ arcing fault were simulated on a real full-scale 360MVA/220kV oil-immersed transformer model, respectively. By employing the finite element method, the transformer internal overpressure distribution, wave propagation and von-Mises stress were solved. The numerical results indicate that the increase of pressure and mechanical stress distribution are non-uniform and the stress tends to concentrate on connecting parts of the tank as the fault time evolves. Given this feature, it becomes possible to reduce the risk of transformer tank rupture through limiting the fault energy and enhancing the mechanical strength of the local stress concentrative areas. The theoretical model and numerical simulation method proposed in this paper can be used as a substitute for risky and costly field tests in fault overpressure analysis and tank mitigation design of transformers. PMID:26230392

  13. Numerical Methods for the Analysis of Power Transformer Tank Deformation and Rupture Due to Internal Arcing Faults.

    PubMed

    Yan, Chenguang; Hao, Zhiguo; Zhang, Song; Zhang, Baohui; Zheng, Tao

    2015-01-01

    Power transformer rupture and fire resulting from an arcing fault inside the tank usually leads to significant security risks and serious economic loss. In order to reveal the essence of tank deformation or explosion, this paper presents a 3-D numerical computational tool to simulate the structural dynamic behavior due to overpressure inside transformer tank. To illustrate the effectiveness of the proposed method, a 17.3 MJ and a 6.3 MJ arcing fault were simulated on a real full-scale 360MVA/220kV oil-immersed transformer model, respectively. By employing the finite element method, the transformer internal overpressure distribution, wave propagation and von-Mises stress were solved. The numerical results indicate that the increase of pressure and mechanical stress distribution are non-uniform and the stress tends to concentrate on connecting parts of the tank as the fault time evolves. Given this feature, it becomes possible to reduce the risk of transformer tank rupture through limiting the fault energy and enhancing the mechanical strength of the local stress concentrative areas. The theoretical model and numerical simulation method proposed in this paper can be used as a substitute for risky and costly field tests in fault overpressure analysis and tank mitigation design of transformers. PMID:26230392

  14. Investigating Earthquake Stress Drops on Mid-Ocean Ridge Transform Faults (Invited)

    NASA Astrophysics Data System (ADS)

    Boettcher, M. S.; Moyer, P. A.; McGuire, J. J.; Collins, J. A.

    2013-12-01

    A key question concerning the development of mid-ocean ridge transform faults (RTFs) is why have full fault ruptures not been observed in the historic record? Similarly, why do the rupture areas of the largest earthquakes on RTFs not scale directly with area above the 600°C isotherm? Recent studies have shown that Blanco, Discovery, Gofar, Heezen, Tharp, and Hollister RTFs all have multiple rupture patches on a single fault segment that repeatedly fail in characteristic largest (Mc) earthquakes. We develop a scaling relation for the stress drop of repeating Mc earthquakes assuming full-coupling on Mc rupture patches, such that slip (Dc) in Mc earthquakes is given by the product of the repeat time (tR) and plate tectonic slip (V), and assuming that slip scales with the square root of rupture area (Ac), Dc = ΔσAc1/2μ-1, where μ is the shear modulus. Using the definition of seismic moment, Mc = μAcDc, we directly solve for stress drop given observed repeat times: Δσ = μVtR3/2Mc-1/2. For stress drops in the range of 1-2 MPa, slip in repeating Mc earthquakes on each of the RTFs noted above is approximately equal to the accumulated plate tectonic motion. We analyze the source parameters of 3.0 < Mw < 5.0 earthquakes recorded in 2008 during a yearlong ocean bottom seismic (OBS) experiment on Gofar transform fault to determine the stress drop of earthquakes in both repeating Mc patches and the rupture barriers between the rupture patches. The OBS deployment captured the end of a seismic cycle, including a foreshock sequence that was both extensive (~20,000 earthquakes within the week prior to the mainshock) and localized (within a ~10 km region), as well as the Mw 6.0 mainshock and its aftershock sequence [McGuire et. al, 2012]. The foreshocks occurred in a rupture barrier on the western segment of Gofar and the aftershocks occurred in the rupture patch. Using waveforms recorded with a sample rate of 50 Hz on OBS accelerometers, we investigate the corner

  15. Stress fields of the San Andreas and Queen Charlotte transform faults

    NASA Astrophysics Data System (ADS)

    Kilty, Kevin T.

    1981-08-01

    Analytic solutions to the stress fields resulting from the San Andreas and Queen Charlotte transform faults may be found by applying conformal mappings to the generalized plane stress solution of stresses in a half-plane. The mean stress fields (one-half the trace of the stress tensor) found in this manner show a similarity to the deformation found in western Canada and the western United States. The results refute the hypothesis that Alaska acts as a continental buttress against deformation of the Canadian Cordillera. Moreover, these results imply that the differences in the tectonics of major transform boundaries are caused primarily by differences in lithospheric structure and differences in stress distribution along the plate boundaries.

  16. The Fethiye-Burdur Fault Zone: A component of upper plate extension of the subduction transform edge propagator fault linking Hellenic and Cyprus Arcs, Eastern Mediterranean

    NASA Astrophysics Data System (ADS)

    Hall, J.; Aksu, A. E.; Elitez, I.; Yaltırak, C.; Çifçi, G.

    2014-11-01

    The Hellenic and Cyprus Arcs, that mark the convergent boundary of the African and Aegean-Anatolian plates, are offset along a subduction transform edge propagator ('STEP') fault running NE-SW along the Pliny and Strabo Trenches. The continuation of the fault to the northeast through the Rhodes Basin and into SW Anatolia is assessed. Seismic reflection profiles show that the structural architecture of the northern sector of the Rhodes Basin includes a large crustal-scale fold-thrust belt which is overprinted by numerous faults with small extensional stratigraphic separations. A protracted episode of convergence in the Miocene resulted in the development of a prominent NE-SW-striking and NW-verging fold-thrust belt in the Rhodes Basin. The absence of evaporites in the Rhodes Basin and several seaward prograded vertically stacked Quaternary delta successions resting at 2500-3500 m water depth collectively suggest that the Rhodes Basin must have remained above the depositional base of marine evaporite environment during the Messinian and that the region must have subsided very rapidly during the Pliocene-Quaternary. During the Pliocene-Quaternary, a NE-SW-trending belt developed across the Rhodes Basin: while the structural framework of this belt was characterised by reactivated thrusts in the central portion of the basin, a prominent zone of NE-SW-striking and NW- and SE-dipping faults with extensional separations developed in the northern portion of the basin. Two seismic profiles running parallel to the present-day coastline provide the much needed linkage between the Fethiye-Burdur Fault Zone onland and the reactivated thrusts in central Rhodes Basin, and show that the Pliocene-Quaternary zone of high-angle faults with extensional separations clearly link with the similarly trending and dipping strike-slip faults onland in the Eşen Valley, thus providing the continuity between the Pliny-Strabo Trenches in the southwest and the Fethiye-Burdur Fault Zone in the

  17. Earthquake Swarms on Transform Faults - A Response to Aseismic Triggering Mechanisms

    NASA Astrophysics Data System (ADS)

    Roland, E. C.; McGuire, J. J.

    2008-12-01

    Swarm-like earthquake sequences are commonly observed in a diverse range of geologic settings, including volcanic and geothermal regions as well as along transform plate boundaries. Earthquake swarms typically lack a clear mainshock, cover large areas relative to their total seismic moment release (implying a low stress drop) and fail to decay in time according to standard aftershock scaling laws (e.g., Omori's Law). Although swarms generally result from a distinct driving phenomenon, such as a magma intrusion event, most lack the geophysical data necessary to constrain their specific driving process. To identify the mechanisms that cause swarms on strike-slip faults, we use relative earthquake relocations to quantify the spatial and temporal characteristics of swarms along Southern California and East Pacific Rise transforms. Swarms in these regions exhibit distinctive moment release and spatial triggering patters, including a relatively narrow range of hypocentral migration velocities, on the order of a kilometer per hour. This rate corresponds well with the rupture velocity of shallow creep transients, which have been observed geodetically in conjunction with swarms in Southern California [1], and is significantly faster than rates associated with fluid diffusion [2]. The uniformity of hypocentral migration rates and low overall stress drops suggest that shallow aseismic creep transients are the primary process driving swarms on strike-slip faults. 1. Lohman, R.B. and McGuire, J.J., J. of Geophys. Res., 2007; 2. Hainzl, S. and Ogata, Y., J. Geophys. Res., 2005

  18. Iterative generalized synchrosqueezing transform for fault diagnosis of wind turbine planetary gearbox under nonstationary conditions

    NASA Astrophysics Data System (ADS)

    Feng, Zhipeng; Chen, Xiaowang; Liang, Ming

    2015-02-01

    The synchrosqueezing transform can effectively improve the readability of time-frequency representation of mono-component and constant frequency signals. However, for multi-component and time-variant frequency signals, it still suffers from time-frequency blurs. In order to address this issue, the synchrosqueezing transform is improved using iterative generalized demodulation. Firstly, the complex nonstationary signal is decomposed into mono-components of constant frequency by iterative generalized demodulation. Then, the instantaneous frequency of each mono-component is accurately estimated via the synchrosqueezing transform, by exploiting its merit of enhanced time-frequency resolution. Finally, the time-frequency representation of the original signal is obtained by superposing the time-frequency representations of all the mono-components with restored instantaneous frequency. This proposed method generalizes the synchrosqueezing transform to multi-component and time-variant frequency signals, and it has fine time-frequency resolution and is free of cross-term interferences. The proposed method was validated using both numerically simulated and lab experimental vibration signals of planetary gearboxes under nonstationary conditions. The time-variant planetary gearbox characteristic frequencies were effectively identified, and the gear faults were correctly diagnosed.

  19. Feature extraction of rolling bearing’s early weak fault based on EEMD and tunable Q-factor wavelet transform

    NASA Astrophysics Data System (ADS)

    Wang, Hongchao; Chen, Jin; Dong, Guangming

    2014-10-01

    When early weak fault emerges in rolling bearing the fault feature is too weak to extract using the traditional fault diagnosis methods such as Fast Fourier Transform (FFT) and envelope demodulation. The tunable Q-factor wavelet transform (TQWT) is the improvement of traditional one single Q-factor wavelet transform, and it is very fit for separating the low Q-factor transient impact component from the high Q-factor sustained oscillation components when fault emerges in rolling bearing. However, it is hard to extract the rolling bearing’ early weak fault feature perfectly using the TQWT directly. Ensemble empirical mode decomposition (EEMD) is the improvement of empirical mode decomposition (EMD) which not only has the virtue of self-adaptability of EMD but also overcomes the mode mixing problem of EMD. The original signal of rolling bearing’ early weak fault is decomposed by EEMD and several intrinsic mode functions (IMFs) are obtained. Then the IMF with biggest kurtosis index value is selected and handled by the TQWT subsequently. At last, the envelope demodulation method is applied on the low Q-factor transient impact component and satisfactory extraction result is obtained.

  20. An Earthquake Swarm on the Galapagos Transform Fault: Implications for Earthquake Triggering

    NASA Astrophysics Data System (ADS)

    Roland, E.; Boettcher, M. S.; McGuire, J. J.

    2004-12-01

    Transform faults on the East Pacific Rise spreading system often have large amounts of seismicity in short periods of time. The magnitude vs. time distribution of these sequences ranges from what would be classified as similar to a typical continental earthquake but with an elevated foreshock to aftershock ratio to sequences that would traditionally be classified as an "earthquake swarm" closer to those seen in volcanic regions (e.g. Forsyth et al., 2003). Analysis of declustered earthquake catalogs (i.e. ignoring the swarms) suggest that the anomalous foreshock to aftershock ratio on EPR transforms requires different triggering processes in the oceanic regime from those that explain continental seismicity. Here we investigate the best recorded earthquake swarm on an EPR transform to evaluate whether it has similar implications. Due to the lack of oceanic earthquake catalogs with low detection thresholds and reliable magnitude estimates, the unique characteristics of transform sequences have been difficult to quantify. This study uses the earthquake catalog derived from NOAA's hydroacoustic array in the equatorial Pacific Ocean and data from a land-based seismometer array on the Galapagos Islands (from Toomey et al.) to examine the temporal and size distribution of an earthquake swarm which occurred on the Galapagos Transform in 2000. Seismic moment estimates are determined with a high degree of accuracy using an Empirical Green's Function based, cross-correlation method. Characteristics of the Galapagos swarm can be compared to that normally observed in continental strike-slip faults by applying the Epidemic Type Aftershock Sequence (ETAS) Model [e.g. Helmstetter and Sorenette, 2002], which is a common earthquake triggering model used to explain continental seismicity. This model assumes aftershocks are triggered from all large earthquakes with a triggering rate that decays in time following the Omori Law and increases with triggering event magnitude. The utility

  1. Generalized stepwise demodulation transform and synchrosqueezing for time-frequency analysis and bearing fault diagnosis

    NASA Astrophysics Data System (ADS)

    Shi, Juanjuan; Liang, Ming; Necsulescu, Dan-Sorin; Guan, Yunpeng

    2016-04-01

    The energy concentration level is an important indicator for time-frequency analysis (TFA). Weak energy concentration would result in time-frequency representation (TFR) diffusion and thus leading to ambiguous results or even misleading signal analysis results, particularly for nonstationary multicomponent signals. To improve the energy concentration level, this paper proposes a generalized stepwise demodulation transform (GSDT). The rationale of the proposed method is that (1) the generalized demodulation (GD) can map the original signal into an analytic signal with constant instantaneous frequency (IF) and improve the energy concentration level on time-frequency plane, and (2) focusing on a short window around the time instant of interest, a backward demodulation operation can recover the original frequency at the time instant without affecting the improved energy concentration level. By repeating the backward demodulation at every time instant of interest, the TFR of the entire signal can be attained with enhanced energy concentration level. With the GSDT, an iterative GSDT (IGSDT) is developed to analyze multicomponent signal that is subjected to different modulating sources for their constituent components. The IGSDT iteratively demodulates each constituent component to attain its TFR and the TFR of the whole signal is derived from superposing all the resulting TFRs of constituent components. The cross-term free and more energy concentrated TFR of the signal is, therefore, obtained, and the diffusion in the TFR can be reduced. The GSDT-based synchrosqueezing transform is also elaborated to further enhance the GSDT(IGSDT) yielded TFR. The effectiveness of the proposed method in TFA is tested using both simulated monocomponent and multicomponent signals. The application of the proposed method to bearing fault detection is explored. Bearing condition and fault pattern can be revealed by the proposed method resulting TFR. The main advantages of the proposed method

  2. Formation and Evolution of the San Cristobal Trough Transform Fault Linking the Southern Solomon Islands and Northern New Hebrides Trenches

    NASA Astrophysics Data System (ADS)

    Furlong, K. P.; Hayes, G. P.; Herman, M. W.; Benz, H.

    2014-12-01

    The San Cristobal Trough, which occupies the southern segment of the South Solomon Trench, hosts a dominantly left-lateral transform plate boundary (SCTF) linking the southern end of the Solomon Islands subduction zone (SISZ) to the northern end of the New Hebrides (Vanuatu) subduction zone (NHSZ). At its western end (SISZ), the Australia plate is torn as a result of the transition from subduction to transform motion. The southern side of the tear translates approximately 375 km along the SCTF before subducting beneath the Santa Cruz Islands at the NHSZ. Earthquakes occurring along this transform reflect the processes of plate tearing, fault zone evolution, and subsequent underthrusting and subduction of the Australia-plate-side of the transform. A knot of earthquake activity at the western end of the SCTF juxtaposes high-angle thrust faulting events with left-lateral strike slip events. These record the tearing of Australian lithosphere, as shown by a recent pair of large earthquakes in that region - a Mw 7.6 strike-slip event (12 April 2014) followed 22 hours later by a Mw 7.4 high-angle reverse faulting event (13 April 2014). Associated displacements reflect oblique tearing (northern-side down and west), allowing the Australia Plate to follow two disparate paths - subduction at the SISZ to the north and translation along the SCTF to the south. Moving eastward along the transform, the plate boundary shows three styles of earthquake activity. The main transform is dominated by shallow, E-W striking, left-lateral faulting and E-W striking thrust faults (with a north-dipping shallow fault plane) - these reflect partitioning of oblique motion along the transform between the Australia and Pacific plates. Outboard (+/- 100 km) of the plate boundary, a group of E-W striking shallow normal faulting events reflect upward bending driven by the convergent component of plate motions. Approaching the NHSZ, normal faulting earthquakes in the Australia Plate rotate clockwise

  3. How Plates Pull Transforms Apart: 3-D Numerical Models of Oceanic Transform Fault Response to Changes in Plate Motion Direction

    NASA Astrophysics Data System (ADS)

    Morrow, T. A.; Mittelstaedt, E. L.; Olive, J. A. L.

    2015-12-01

    Observations along oceanic fracture zones suggest that some mid-ocean ridge transform faults (TFs) previously split into multiple strike-slip segments separated by short (<~50 km) intra-transform spreading centers and then reunited to a single TF trace. This history of segmentation appears to correspond with changes in plate motion direction. Despite the clear evidence of TF segmentation, the processes governing its development and evolution are not well characterized. Here we use a 3-D, finite-difference / marker-in-cell technique to model the evolution of localized strain at a TF subjected to a sudden change in plate motion direction. We simulate the oceanic lithosphere and underlying asthenosphere at a ridge-transform-ridge setting using a visco-elastic-plastic rheology with a history-dependent plastic weakening law and a temperature- and stress-dependent mantle viscosity. To simulate the development of topography, a low density, low viscosity 'sticky air' layer is present above the oceanic lithosphere. The initial thermal gradient follows a half-space cooling solution with an offset across the TF. We impose an enhanced thermal diffusivity in the uppermost 6 km of lithosphere to simulate the effects of hydrothermal circulation. An initial weak seed in the lithosphere helps localize shear deformation between the two offset ridge axes to form a TF. For each model case, the simulation is run initially with TF-parallel plate motion until the thermal structure reaches a steady state. The direction of plate motion is then rotated either instantaneously or over a specified time period, placing the TF in a state of trans-tension. Model runs continue until the system reaches a new steady state. Parameters varied here include: initial TF length, spreading rate, and the rotation rate and magnitude of spreading obliquity. We compare our model predictions to structural observations at existing TFs and records of TF segmentation preserved in oceanic fracture zones.

  4. Evidence for ground-rupturing earthquakes on the Northern Wadi Araba fault at the archaeological site of Qasr Tilah, Dead Sea Transform fault system, Jordan

    NASA Astrophysics Data System (ADS)

    Haynes, Jeremy M.; Niemi, Tina M.; Atallah, Mohammad

    2006-10-01

    The archaeological site of Qasr Tilah, in the Wadi Araba, Jordan is located on the northern Wadi Araba fault segment of the Dead Sea Transform. The site contains a Roman-period fort, a late Byzantine Early Umayyad birkeh (water reservoir) and aqueduct, and agricultural fields. The birkeh and aqueduct are left-laterally offset by coseismic slip across the northern Wadi Araba fault. Using paleoseismic and archaeological evidence collected from a trench excavated across the fault zone, we identified evidence for four ground-rupturing earthquakes. Radiocarbon dating from key stratigraphic horizons and relative dating using potsherds constrains the dates of the four earthquakes from the sixth to the nineteenth centuries. Individual earthquakes were dated to the seventh, ninth and eleventh centuries. The fault strand that slipped during the most recent event (MRE) extends to just below the modern ground surface and juxtaposes alluvial-fan sediments that lack in datable material with the modern ground surface, thus preventing us from dating the MRE except to constrain the event to post-eleventh century. These data suggest that the historical earthquakes of 634 or 659/660, 873, 1068, and 1546 probably ruptured this fault segment.

  5. Agulhas Ridge, South Atlantic: the peculiar structure of a transform fault

    NASA Astrophysics Data System (ADS)

    Uenzelmann-Neben, G.; Gohl, K.

    2003-04-01

    Transform faults constitute conservative plate boundaries, where adjacent plates are in tangential contact. Transform faults in the ocean are marked by fracture zones, which are long, linear, bathymetric depressions. One of the largest transform offsets on Earth can be found in the South Atlantic. The 1200 km long Agulhas Falkland Fracture Zone (AFFZ), form by this, developed during the Early Cretaceous break-up of West Gondwana. Between approx. 41°S, 16°E and 43°S, 9°E the Agulhas Falkland Fracture Zone is characterised by a pronounced topographic anomaly, the Agulhas Ridge. The Agulhas Ridge rises more than 2 km above the surrounding seafloor. The only equivalent to this kind of topographic high, as part of the AFFZ, is found in form of marginal ridges along the continental parts of the fracture zone, namely the Falkland Escarpment at the South American continent and the Diaz Ridge adjacent to South Africa. But the Agulhas Ridge differs from both the Falkland Escarpment and the Diaz Ridge in the facts (1) that it was not formed during the early rift-drift phase, and (2) that it separates oceanic crust of different age and not continental from oceanic crust. A set of high-resolution seismic reflection data (total length 2000 km) and a seismic refraction line across the Agulhas Ridge give new information on the crustal and basement structure of this tectonic feature. We have observed that within the Cape Basin, to the North, the basement and sedimentary layers are in parts strongly deformed. We observe basement highs, which point towards intrusions. Both the basement and the sedimentary sequence show strong faulting. This points towards a combined tectono-magmatic activity, which led to the formation of basement ridges parallel to the Agulhas Ridge. Since at least the pre-Oligocene parts and, locally, the whole sedimentary column are affected we infer that the renewed activity began in the Middle Oligocene and may have lasted into the Quaternary. As an origin

  6. The Origin of Hydrous Minerals in Peridotite Mylonites from an Oceanic Transform Fault

    NASA Astrophysics Data System (ADS)

    Deems, N. J.; Warren, J. M.; McCubbin, F. M.; Wolfson-Schwehr, M.

    2014-12-01

    Previous studies of oceanic transform faults have assumed that fluid circulation ends when the transition from brittle failure to plastic flow occurs. However, we have identified significant amounts of hydrous minerals in peridotite mylonites from St. Paul's Rocks, a small set of islets on the St. Paul Transform Fault on the Mid-Atlantic Ridge. These rocks, which are highly deformed, are interpreted as having originated within the brittle-ductile transition zone. Our analyses show that the peridotites contain syn-deformational amphibole (12% on average) and minor phlogopite. In addition, the mylonites contain cm-scale veins of gabbro that are semi-parallel to foliation, which have been altered to amphibole, sodalite, and scapolite. Microprobe analysis indicates that the amphibole is pargasite, which is relatively rich in Na and Cl and requires temperatures >~700°C to form. In addition, sodalite and scapolite contain Na and Cl as essential elements. Initial stable isotope analysis indicates that δD of the pargasite lies between mantle δD (~70‰) and seawater (0‰). Based on our observations, we suggest that melt was introduced into the system either prior to or during deformation. In addition, we propose that either i) the melt was volatile-rich, providing the necessary water to form hydrous phases; or ii) seawater penetrated into the brittle-ductile transition zone by microfracturing, thus providing the necessary water, Na, and Cl to form the phases observed. While the 600°C isotherm is traditionally considered the limit of brittle deformation, this second hypothesis would suggest that seawater can penetrate to greater depths, in agreement with recent seismicity observations from an East Pacific Rise transform fault (McGuire et al., 2012). With additional stable isotope analysis and thermodynamic modeling, we plan to further constrain the source of melt/fluid at St. Paul's Rocks and thus improve constraints on OTF processes. If seawater is the origin of syn

  7. The 2015 Mw 7.1 earthquake on the Charlie-Gibbs transform fault: Repeating earthquakes and multimodal slip on a slow oceanic transform

    NASA Astrophysics Data System (ADS)

    Aderhold, K.; Abercrombie, R. E.

    2016-06-01

    The 2015 Mw 7.1 earthquake on the Charlie-Gibbs transform fault along the Mid-Atlantic Ridge is the latest in a series of seven large earthquakes since 1923. We propose that these earthquakes form a pair of quasi-repeating sequences with the largest magnitudes and longest repeat times for such sequences observed to date. We model teleseismic body waves and find that the 2015 earthquake ruptured a distinct segment of the transform from the previous 1998 earthquake. The two events display similarities to earthquakes in 1974 and 1967, respectively. We observe large oceanic transform earthquakes to exhibit characteristic slip behavior, initiating with small slip near the ridge, and propagating unilaterally to significant slip asperities nearer the center of the transform. These slip distributions combined with apparent segmentation support multimode slip behavior with fault slip accommodated both seismically during large earthquakes and aseismically in between.

  8. Absolute Locations of Repeating Mw 5.5 - 6.0 Earthquakes on Discovery Transform Fault, EPR

    NASA Astrophysics Data System (ADS)

    Wolfson, M. L.; Boettcher, M. S.; McGuire, J. J.; Collins, J. A.

    2011-12-01

    Previous studies have shown that seismic cycles on intermediate and fast-slipping oceanic transform faults (OTFs) are remarkably regular [Boettcher and McGuire, 2009; McGuire, 2008]. The largest earthquakes on these OTFs are small compared to total fault area and are separated by rupture barriers [McGuire et al., 2011]. Here we investigate how the rupture patches on Discovery Transform Fault, East Pacific Rise (EPR) correlate with seafloor fault zone structure. We use a surface wave relative relocation technique [McGuire, 2008] to determine absolute locations of the largest earthquakes and compare these locations with high-resolution bathymetric data. Discovery transform fault, located at 4S on the EPR, consists of two sub-parallel fault segments separated by an intra-transform spreading center (ITSC). We used two multibeam bathymetry datasets, a Seabeam 2012 dataset collected in 2006 and an EM300 dataset collected in 2008, to delineate fault structure on a sub-kilometer scale. The western segment fault zone is narrow and well-defined (300-500 m wide) within ~7 km of the ridge crest. To the east the fault zone broadens into a lozenge-shaped valley (~12 km long and ~5 km wide) that is terminated to the east by a 3-km wide ridge that crosscuts the transform domain. East of this ridge, the western segment splays into two sub-parallel linear features that persist to the ITSC, both of which appear to be active fault traces. The eastern segment of Discovery is comprised of one primary fault trace that grades from a relatively narrow (1.5 km) fault zone east of the ITSC into a broad (5 km) nodal basin at the eastern ridge-transform intersection. Previously McGuire [2008] found four distinct groups of repeating Mw 5.5 - 6.0 earthquakes in the region of the Discovery transform fault. The data used were obtained from the global Moment Tensor (CMT) catalog, which has poor location resolution for mid-ocean earthquakes, with errors of up to ~45 km for the events relocated in

  9. Crustal extension and transform faulting in the southern Basin Range Province. [California, Arizona, and Nevada

    NASA Technical Reports Server (NTRS)

    Liggett, M. A. (Principal Investigator); Childs, J. F.

    1974-01-01

    The author has identified the following significant results. Field reconnaissance and study of geologic literature guided by analysis of ERTS-1 MSS imagery have led to a hypothesis of tectonic control of Miocene volcanism, plutonism, and related mineralization in part of the Basin Range Province of southern Nevada and northwestern Arizona. The easterly trending right-lateral Las Vegas Shear Zone separates two volcanic provinces believed to represent areas of major east-west crustal extension. One volcanic province is aligned along the Colorado River south of the eastern termination of the Las Vegas Shear Zone; the second province is located north of the western termination of the shear zone in southern Nye County, Nevada. Geochronologic, geophysical, and structural evidence suggests that the Las Vegas Shear Zone may have formed in response to crustal extension in the two volcanic provinces in a manner similar to the formation of a ridge-ridge transform fault, as recognized in ocean floor tectonics.

  10. Fault diagnosis of rolling element bearing based on S transform and gray level co-occurrence matrix

    NASA Astrophysics Data System (ADS)

    Zhao, Minghang; Tang, Baoping; Tan, Qian

    2015-08-01

    Time-frequency analysis is an effective tool to extract machinery health information contained in non-stationary vibration signals. Various time-frequency analysis methods have been proposed and successfully applied to machinery fault diagnosis. However, little research has been done on bearing fault diagnosis using texture features extracted from time-frequency representations (TFRs), although they may contain plenty of sensitive information highly related to fault pattern. Therefore, to make full use of the textural information contained in the TFRs, this paper proposes a novel fault diagnosis method based on S transform, gray level co-occurrence matrix (GLCM) and multi-class support vector machine (Multi-SVM). Firstly, S transform is chosen to generate the TFRs due to its advantages of providing frequency-dependent resolution while keeping a direct relationship with the Fourier spectrum. Secondly, the famous GLCM-based texture features are extracted for capturing fault pattern information. Finally, as a classifier which has good discrimination and generalization abilities, Multi-SVM is used for the classification. Experimental results indicate that the GLCM-based texture features extracted from TFRs can identify bearing fault patterns accurately, and provide higher accuracies than the traditional time-domain and frequency-domain features, wavelet packet node energy or two-direction 2D linear discriminant analysis based features of the same TFRs in most cases.

  11. The influence of changing plate kinematics on a continental transform fault; the example of the Dead Sea Fault Zone

    NASA Astrophysics Data System (ADS)

    Smit, J.; Brun, J. P.; Cloetingh, S.

    2003-04-01

    The Dead Sea Fault Zone forms the boundary between the Sinai and Arabian plates and links the Red Sea spreading center in the South to the Taurus Mountains in the North. From field observations along the Southern part of the Dead Sea Fault zone (DSFZ) and investigations in the Red Sea area it has been suggested that the Arabian plate moves northward along the DSFZ by a rotation along an Euler pole that for the last 4 Ma years is located at 33°N23°E. It has also been suggested that this Euler pole was located about 5° more to the West during the first episode of movement. This change in motion of the Arabian plate coincides with the initiation of the main subsidence in the Dead Sea basin and the Gulf of Aqaba. The geometry and timing of deformation along the Northern segment of the DSFZ is much less constrained and different models have been proposed for the history of this segment. To study the influence of the change in plate motion on the DSFZ, a series of laboratory experiments has been performed. Special attention is being paid to the influence of rheologies on the system, the development of the fault zones geometry in time and with depth and wether a new rotational pole forces the initiation of a new fault or that the movement is accommodated by trenspression-transtension along the old fault.

  12. Formation of the Red Hills Ultramafic Massif during Subduction Initiation along an Oceanic Transform Fault

    NASA Astrophysics Data System (ADS)

    Tikoff, B.; Stewart, E. D.; Newman, J.; Lamb, W. M.

    2015-12-01

    The Red Hills ultramafic massif in the South Island, New Zealand, is part of the Dun Mountain Ophiolite Belt (DMOB). The DMOB was created at the onset of subduction in a forearc setting in the Middle Permian, and it likely formed immediately prior to the establishment of a magmatic arc along the New Zealand and Australian portions of the Gondwanan margin. The Red Hills ultramafic massif records a two-stage history of high temperature mantle flow during subduction initiation along the Gondwanan margin. Initial deformation was homogeneous and fabrics are constrictional. Kilometer-scale deformation zones, part of the second stage of deformation, overprinted the early homogeneous fabric throughout the western portion of the massif. Timing of all high-temperature mantle deformation in the Red Hills was between 285 and 274 Ma during subduction initiation based on the earliest ages of igneous activity in adjacent volcanic rocks, and a new U-Pb zircon age of 274.55±0.43 Ma from a cross-cutting dike. We present a kinematic model to explain the occurrence of the constructional fabrics during subduction initiation, and find that the three-dimensional boundary conditions for deformation in the incipient mantle wedge must have been transtensional, with a dominant trench-parallel component of motion. Such a scenario indicates subduction likely initiated along an active oceanic transform fault. We test this model by kinematically restoring the Red Hills ultramafics to their Permian orientation, and find the consistent elongation direction of the constructional fabrics was oriented nearly parallel to the trench. Stage 2 deformation zones were variably oriented, but all accommodated normal motion. These results support a model where the incipient mantle wedge was undergoing highly oblique transtension, and the lack of evidence for contraction suggests the onset of subduction along the Permian margin of New Zealand occurred along a transform fault due to spontaneous, density driven

  13. Recent volcanism in the Siqueiros transform fault: Picritic basalts and implications for MORB magma genesis

    USGS Publications Warehouse

    Perfit, M.R.; Fornari, D.J.; Ridley, W.I.; Kirk, P.D.; Casey, J.; Kastens, K.A.; Reynolds, J.R.; Edwards, M.; Desonie, D.; Shuster, R.; Paradis, S.

    1996-01-01

    Small constructional volcanic landforms and very fresh-looking lava flows are present along one of the inferred active strike-slip faults that connect two small spreading centers (A and B) in the western portion of the Siqueiros transform domain. The most primitive lavas (picritic and olivine-phyric basalts), exclusively recovered from the young-looking flows within the A-B strike-slip fault, contain millimeter-sized olivine phenocrysts (up to 20 modal%) that have a limited compositional range (Fo91.5-Fo89.5) and complexly zoned Cr-Al spinels. High-MgO (9.5-10.6 wt%) glasses sampled from the young lava flows contain 1-7% olivine phenocrysts (Fo90.5-Fo89) that could have formed by equilibrium crystallization from basaltic melts with Mg# values between 71 and 74. These high MgO (and high Al2O3) glasses may be near-primary melts from incompatible-element depleted oceanic mantle and little modified by crustal mixing and/or fractionation processes. Phase chemistry and major element systematics indicate that the picritic basalts are not primary liquids and formed by the accumulation of olivine and minor spinel from high-MgO melts (10% < MgO < 14%). Compared to typical N-MORB from the East Pacific Rise, the Siqueiros lavas are more primitive and depleted in incompatible elements. Phase equilibria calculations and comparisons with experimental data and trace element modeling support this hypothesis. They indicate such primary mid-ocean ridge basalt magmas formed by 10-18% accumulative decompression melting in the spinel peridotite field (but small amounts of melting in the garnet peridotite field are not precluded). The compositional variations of the primitive magmas may result from the accumulation of different small batch melt fractions from a polybaric melting column.

  14. Sparsity-enabled signal decomposition using tunable Q-factor wavelet transform for fault feature extraction of gearbox

    NASA Astrophysics Data System (ADS)

    Cai, Gaigai; Chen, Xuefeng; He, Zhengjia

    2013-12-01

    Localized faults in gearboxes tend to result in periodic shocks and thus arouse periodic responses in vibration signals. Feature extraction has always been a key problem for localized fault diagnosis. This paper proposes a new fault feature extraction technique for gearboxes by using sparsity-enabled signal decomposition method. The sparsity-enabled signal decomposition method separates signals based on the oscillatory behavior of the signal rather than the frequency or scale. Thus, the fault feature can be nonlinearly extracted from vibration signals. During the implementation of the proposed method, tunable Q-factor wavelet transform, for which the Q-factor can be easily specified, is adopted to represent vibration signals in a sparse way, and then morphological component analysis (MCA) is employed to estimate and separate the distinct components. The corresponding optimization problem of MCA is solved by the split augmented Lagrangian shrinkage algorithm (SALSA). With the proposed method, vibration signals of the faulty gearbox can be nonlinearly decomposed into high-oscillatory component and low-oscillatory component which is the fault feature of gearboxes. To evaluate the performance of the proposed method, this paper investigates the effect of two parameters pertinent to MCA and SALSA: the Lagrange multiplier and the penalty parameter. The effectiveness of the proposed method is verified by both the simulated and practical gearbox vibration signals. Results show the proposed method outperforms empirical mode decomposition and spectral kurtosis in extracting fault features of gearboxes.

  15. Evidence for local shifting of the main fault and changes in the structural setting, Kinarot basin, Dead Sea transform

    SciTech Connect

    Rotstein, Y.; Frieslander, U. ); Bartov, Y. )

    1992-03-01

    Two new high-resolution seismic reflection profiles from the Kinarot Valley, Dead Sea rift, analyzed with older conventional oil exploration profiles, throw light on the Quaternary evolution of the African-Arabian transform-type plate boundary in the area. The present en echelon main faults of the Dead Sea transform are observed in the seismic data as wide zones of deformation rather than as distinct fault planes. A similar zone of deformation is observed in the center of the Kinarot basin and may be associated with an extinct trace of the main fault. The Zemah structure, previously mapped and drilled, is shown by the new data to be an inactive anticline. Compression within the basin is suggested as being the result of motion along the now inactive main fault observed in the center of the basin. Compression and shortening started some 2 m.y. ago and ended late in the Quaternary as a result of changes in the geometry of the transform. At present the Kinarot basin is subsiding.

  16. Oceanic transform earthquakes with unusual mechanisms or locations - Relation to fault geometry and state of stress in the adjacent lithosphere

    NASA Technical Reports Server (NTRS)

    Wolfe, Cecily J.; Bergman, Eric A.; Solomon, Sean C.

    1993-01-01

    Results are presented of a search for transform earthquakes departing from the pattern whereby they occur on the principal transform displacement zone (PTDZ) and have strike-slip mechanisms consistent with transform-parallel motion. The search was conducted on the basis of source mechanisms and locations taken from the Harvard centroid moment tensor catalog and the bulletin of the International Seismological Center. The source mechanisms and centroid depths of 10 such earthquakes on the St. Paul's, Marathon, Owen, Heezen, Tharp, Menard, and Rivera transforms are determined from inversions of long-period body waveforms. Much of the anomalous earthquake activity on oceanic transforms is associated with complexities in the geometry of the PTDZ or the presence of large structural features that may influence slip on the fault.

  17. Imaging of the along-strike variations in mechanical properties along the Gofar transform fault, East Pacific Rise (Invited)

    NASA Astrophysics Data System (ADS)

    Froment, B.; McGuire, J. J.; van der Hilst, R. D.; Gouedard, P.; Roland, E. C.; Collins, J. A.

    2013-12-01

    Recent work has documented strong along-strike variations in the ability of oceanic transform faults to generate large earthquakes. Large East Pacific Rise transform earthquakes occur quasi-periodically in well-defined seismic cycles. Here, we focus on the Gofar transform fault (~ 4,5°S; 106°W). This short (~100 km) fault segment is subdivided into multiple patches that repeat as magnitude 5.5-6 earthquakes roughly every 5 years. The patches that generate large earthquakes are separated by stationary, velocity-strengthening, rupture barriers that prevent large ruptures from covering an entire fault segment. Instead, these barrier regions release strain through aseismic creep transients, seismic swarms of smaller events, or a combination of the two. The purpose of this project is to understand processes that control these different mechanical behaviors. We use the double-difference (DD) tomography technique to examine along-strike variations in the seismic velocity structure as well as in seismicity location. Results show a clear correlation between the velocity structure and the mechanical behavior of the different segments, the barrier regions corresponding to zones of low P-wave velocity anomalies. This agrees with results from an active-source wide-angle refraction dataset that has been collected perpendicular to the fault, around the barrier region. The high-resolution image obtained from this active source survey shows that the low velocity anomaly extends to the Moho and is consistent with a porosity of a few percent. Besides, the seismicity relocated with the DD technique defines a very thin and linear fault zone, ruling out the presence of a geometric barrier and giving insights into the geometry of such faults. By using 1-year continuous measurements around one of the regular Mw6 earthquakes, we also examine the spatial dependency of the temporal seismic velocity changes during the seismic cycle to extract information about the different mechanical

  18. Multiple strike slip faults sets: A case study from the Dead Sea transform

    NASA Technical Reports Server (NTRS)

    Ron, Hagai; Nur, Amos; Eyal, Y.

    1990-01-01

    In many strike slip tectonic settings, large rotations of crust blocks about vertical axes have been inferred from paleomagnetic data. These blocks are bounded by sets of parallel faults which presumably accommodate the relative motion between the blocks as regional deformation progress. A mechanical model by Nur et al., (1986) suggests that rotations greater than phi sub c equals 25 to 45 degrees must be accommodated by more than one set of faults, with angle phi sub c between their direction; consequently the sum of the angles between sets must be roughly equal to the total tectonic material rotation. To test this model, the authors investigated the fault geometry and field relation of fault sets in the Mt. Hermon area in northern Israel, where paleomagnetic declination implies data 69 degrees plus or minus 13 degrees counter-clockwise block rotation. The statistical and field relation analysis of over 315 faults shows that the faulting is predominantly right lateral strike slip consisting of three distinct sets. The oldest set strikes 253 degrees, the second oldest set strikes 293 degrees and the youngest strikes 339 degrees. This last direction is consistent also with the current north-south direction of the maximum principle stress axis. The angle phi sub c between the first and second sets is 39 degrees and between the second and third sets 46 degrees, in good agreement with the phi sub c angle predicted from mechanical considerations. The sum of the two angles is 85 degrees, in good agreement with the 69 degrees plus or minus 13 degrees CCW paleomagnetically derived rotation. The results suggest specifically that the sequential development of multiple intersecting fault sets is responsible for the faulting in the Mt. Hermon area; and generally that the model of block rotation with multiple faults provides very good simple rules for analyzing very complex fault patterns.

  19. Kinematics of a Strike-Slip Fault Segment at Various Time Scales, Determined From GPS and Geomorphic Measurements: the Example of the Wadi Araba Fault, Dead Sea Transform.

    NASA Astrophysics Data System (ADS)

    Le Beon, M.; Klinger, Y.; Amrat, A.; Agnon, A.; Meriaux, A.; Dorbath, L.; Baer, G.; Finkel, R. C.; Ruegg, J.; Charade, O.; Elias, A.; Mayyas, O.; Ryerson, F. J.; Tapponnier, P.

    2008-12-01

    This work investigates slip rate evolution over time along one large strike-slip fault, the Dead Sea Transform (DST), which is the 1000-km long plate boundary between the Arabia plate and the Sinai sub-plate. We focus on the Wadi Araba fault, the southernmost segment of the DST. No agreement has been reached yet about the slip rate of the DST. Proposed values vary from 2 to 10 mm/yr. Here, we present results from GPS profiles and measurements of offset geomorphologic features, which ages are comprised between 10 ka and ~300 ka. We installed 17 campaign-style GPS sites distributed along three profiles perpendicular to the fault, with far-field points up to 90 km away from the fault. The sites have been measured twice, in 1999 and 2005, during 48h-long sessions. Campaign data are complemented by data from permanent stations in Israel. Using a locked-fault model, we estimate the present-day slip rate to be 4.9 ± 1.4 mm/yr over 6 years. To estimate the slip rate over longer periods of time, we targeted abandoned alluvial fans offset by the fault at four sites. We mapped and sampled these sites for 10Be cosmogenic dating. At one site, best offset of 48 ± 7 m of a surface dated at 12.1 ± 3.6 ka yields a slip rate of 4.6 ± 2 mm/yr, in very good agreement with the present-day slip rate. Moreover, our morphologic analysis at this site invalidates previous study that suggested a value of 10 mm/yr. At a second site, an offset of 137 ± 7 m of a surface younger than ~50 ka provides a minimum slip rate of 2.6 mm/yr and a larger offset of 598 ± 30 of a surface interpreted to be 93.7 ± 35.4 ka old leads to a slip rate of 7.4 ± 3 mm/yr. The offsets determined at the two other sites, where we obtained ages comprised between 50 to ~300 ka, turned out not to be precise enough to bring new constraints on a Middle to Late Pleistocene time scale. Yet, these results are not inconsistent with previous intervals. Although variations in fault slip rate at the time scale of a few ten

  20. A Novel Characteristic Frequency Bands Extraction Method for Automatic Bearing Fault Diagnosis Based on Hilbert Huang Transform

    PubMed Central

    Yu, Xiao; Ding, Enjie; Chen, Chunxu; Liu, Xiaoming; Li, Li

    2015-01-01

    Because roller element bearings (REBs) failures cause unexpected machinery breakdowns, their fault diagnosis has attracted considerable research attention. Established fault feature extraction methods focus on statistical characteristics of the vibration signal, which is an approach that loses sight of the continuous waveform features. Considering this weakness, this article proposes a novel feature extraction method for frequency bands, named Window Marginal Spectrum Clustering (WMSC) to select salient features from the marginal spectrum of vibration signals by Hilbert–Huang Transform (HHT). In WMSC, a sliding window is used to divide an entire HHT marginal spectrum (HMS) into window spectrums, following which Rand Index (RI) criterion of clustering method is used to evaluate each window. The windows returning higher RI values are selected to construct characteristic frequency bands (CFBs). Next, a hybrid REBs fault diagnosis is constructed, termed by its elements, HHT-WMSC-SVM (support vector machines). The effectiveness of HHT-WMSC-SVM is validated by running series of experiments on REBs defect datasets from the Bearing Data Center of Case Western Reserve University (CWRU). The said test results evidence three major advantages of the novel method. First, the fault classification accuracy of the HHT-WMSC-SVM model is higher than that of HHT-SVM and ST-SVM, which is a method that combines statistical characteristics with SVM. Second, with Gauss white noise added to the original REBs defect dataset, the HHT-WMSC-SVM model maintains high classification accuracy, while the classification accuracy of ST-SVM and HHT-SVM models are significantly reduced. Third, fault classification accuracy by HHT-WMSC-SVM can exceed 95% under a Pmin range of 500–800 and a m range of 50–300 for REBs defect dataset, adding Gauss white noise at Signal Noise Ratio (SNR) = 5. Experimental results indicate that the proposed WMSC method yields a high REBs fault classification accuracy

  1. A Novel Characteristic Frequency Bands Extraction Method for Automatic Bearing Fault Diagnosis Based on Hilbert Huang Transform.

    PubMed

    Yu, Xiao; Ding, Enjie; Chen, Chunxu; Liu, Xiaoming; Li, Li

    2015-01-01

    Because roller element bearings (REBs) failures cause unexpected machinery breakdowns, their fault diagnosis has attracted considerable research attention. Established fault feature extraction methods focus on statistical characteristics of the vibration signal, which is an approach that loses sight of the continuous waveform features. Considering this weakness, this article proposes a novel feature extraction method for frequency bands, named Window Marginal Spectrum Clustering (WMSC) to select salient features from the marginal spectrum of vibration signals by Hilbert-Huang Transform (HHT). In WMSC, a sliding window is used to divide an entire HHT marginal spectrum (HMS) into window spectrums, following which Rand Index (RI) criterion of clustering method is used to evaluate each window. The windows returning higher RI values are selected to construct characteristic frequency bands (CFBs). Next, a hybrid REBs fault diagnosis is constructed, termed by its elements, HHT-WMSC-SVM (support vector machines). The effectiveness of HHT-WMSC-SVM is validated by running series of experiments on REBs defect datasets from the Bearing Data Center of Case Western Reserve University (CWRU). The said test results evidence three major advantages of the novel method. First, the fault classification accuracy of the HHT-WMSC-SVM model is higher than that of HHT-SVM and ST-SVM, which is a method that combines statistical characteristics with SVM. Second, with Gauss white noise added to the original REBs defect dataset, the HHT-WMSC-SVM model maintains high classification accuracy, while the classification accuracy of ST-SVM and HHT-SVM models are significantly reduced. Third, fault classification accuracy by HHT-WMSC-SVM can exceed 95% under a Pmin range of 500-800 and a m range of 50-300 for REBs defect dataset, adding Gauss white noise at Signal Noise Ratio (SNR) = 5. Experimental results indicate that the proposed WMSC method yields a high REBs fault classification accuracy and a

  2. A Novel Characteristic Frequency Bands Extraction Method for Automatic Bearing Fault Diagnosis Based on Hilbert Huang Transform.

    PubMed

    Yu, Xiao; Ding, Enjie; Chen, Chunxu; Liu, Xiaoming; Li, Li

    2015-11-03

    Because roller element bearings (REBs) failures cause unexpected machinery breakdowns, their fault diagnosis has attracted considerable research attention. Established fault feature extraction methods focus on statistical characteristics of the vibration signal, which is an approach that loses sight of the continuous waveform features. Considering this weakness, this article proposes a novel feature extraction method for frequency bands, named Window Marginal Spectrum Clustering (WMSC) to select salient features from the marginal spectrum of vibration signals by Hilbert-Huang Transform (HHT). In WMSC, a sliding window is used to divide an entire HHT marginal spectrum (HMS) into window spectrums, following which Rand Index (RI) criterion of clustering method is used to evaluate each window. The windows returning higher RI values are selected to construct characteristic frequency bands (CFBs). Next, a hybrid REBs fault diagnosis is constructed, termed by its elements, HHT-WMSC-SVM (support vector machines). The effectiveness of HHT-WMSC-SVM is validated by running series of experiments on REBs defect datasets from the Bearing Data Center of Case Western Reserve University (CWRU). The said test results evidence three major advantages of the novel method. First, the fault classification accuracy of the HHT-WMSC-SVM model is higher than that of HHT-SVM and ST-SVM, which is a method that combines statistical characteristics with SVM. Second, with Gauss white noise added to the original REBs defect dataset, the HHT-WMSC-SVM model maintains high classification accuracy, while the classification accuracy of ST-SVM and HHT-SVM models are significantly reduced. Third, fault classification accuracy by HHT-WMSC-SVM can exceed 95% under a Pmin range of 500-800 and a m range of 50-300 for REBs defect dataset, adding Gauss white noise at Signal Noise Ratio (SNR) = 5. Experimental results indicate that the proposed WMSC method yields a high REBs fault classification accuracy and a

  3. Four-Dimensional Transform Fault Processes: Evolution of Step-Overs and Bends at Different Scales

    NASA Astrophysics Data System (ADS)

    Wakabayashi, J.; Hengesh, J. V.; Sawyer, T. L.

    2002-12-01

    Many bends or step-overs along strike-slip faults may evolve by propagation of the strike-slip fault on one side of the structure and progressive shut off of the strike-slip fault on the other side. In such a process, new transverse structures form, old ones become inactive, and the bend or step-over region migrates with respect to materials that were once affected by it. This process is the progressive asymmetric development of a strike-slip duplex. Consequences of this type of step-over evolution include the following: 1. the amount of vertical structural relief in restraining step-over or bend regions is less than expected (apatite fission track ages associated with these step-over regions predate the strike-slip faulting); 2. pull-apart basin deposits are left outside of the active basin and commonly subjected to contractional deformation and uplift; and 3. local basin inversion occurs that is not linked to regional plate motion changes. This type of evolution of step-overs and bends may be common along the dextral San Andreas fault system of California. Examples of pull-apart basin deposits related to migrating releasing () bends or step-overs are the Plio-Pleistocene Merced Formation (tens of km along strike), the Pleistocene Olema Creek Formation (several km along strike) along the San Andreas fault in the San Francisco Bay area, and an inverted colluvial graben exposed in a paleoseismic trench across the Miller Creek fault (meters to tens of meters along strike) in the eastern San Francisco Bay area. Examples of migrating restraining bends or step-overs include the transfer of slip from the Calaveras to Hayward fault in the Mission Peak area, and the Greenville to the Concord fault at Mount Diablo (10 km or more along strike), the offshore San Gregorio fold and thrust belt (40 km along strike), and the progressive transfer of slip from the eastern faults of the San Andreas system to the migrating Mendocino triple junction (over 150 km along strike). Another

  4. Four-dimensional transform fault processes: progressive evolution of step-overs and bends

    NASA Astrophysics Data System (ADS)

    Wakabayashi, John; Hengesh, James V.; Sawyer, Thomas L.

    2004-11-01

    Many bends or step-overs along strike-slip faults may evolve by propagation of the strike-slip fault on one side of the structure and progressive shut-off of the strike-slip fault on the other side. In such a process, new transverse structures form, and the bend or step-over region migrates with respect to materials that were once affected by it. This process is the progressive asymmetric development of a strike-slip duplex. Consequences of this type of step-over evolution include: (1) the amount of structural relief in the restraining step-over or bend region is less than expected; (2) pull-apart basin deposits are left outside of the active basin; and (3) local tectonic inversion occurs that is not linked to regional plate boundary kinematic changes. This type of evolution of step-overs and bends may be common along the dextral San Andreas fault system of California; we present evidence at different scales for the evolution of bends and step-overs along this fault system. Examples of pull-apart basin deposits related to migrating releasing (right) bends or step-overs are the Plio-Pleistocene Merced Formation (tens of km along strike), the Pleistocene Olema Creek Formation (several km along strike) along the San Andreas fault in the San Francisco Bay area, and an inverted colluvial graben exposed in a paleoseismic trench across the Miller Creek fault (meters to tens of meters along strike) in the eastern San Francisco Bay area. Examples of migrating restraining bends or step-overs include the transfer of slip from the Calaveras to Hayward fault, and the Greenville to the Concord fault (ten km or more along strike), the offshore San Gregorio fold and thrust belt (40 km along strike), and the progressive transfer of slip from the eastern faults of the San Andreas system to the migrating Mendocino triple junction (over 150 km along strike). Similar 4D evolution may characterize the evolution of other regions in the world, including the Dead Sea pull-apart, the Gulf

  5. Feature extraction and recognition for rolling element bearing fault utilizing short-time Fourier transform and non-negative matrix factorization

    NASA Astrophysics Data System (ADS)

    Gao, Huizhong; Liang, Lin; Chen, Xiaoguang; Xu, Guanghua

    2015-01-01

    Due to the non-stationary characteristics of vibration signals acquired from rolling element bearing fault, the time-frequency analysis is often applied to describe the local information of these unstable signals smartly. However, it is difficult to classify the high dimensional feature matrix directly because of too large dimensions for many classifiers. This paper combines the concepts of time-frequency distribution(TFD) with non-negative matrix factorization(NMF), and proposes a novel TFD matrix factorization method to enhance representation and identification of bearing fault. Throughout this method, the TFD of a vibration signal is firstly accomplished to describe the localized faults with short-time Fourier transform(STFT). Then, the supervised NMF mapping is adopted to extract the fault features from TFD. Meanwhile, the fault samples can be clustered and recognized automatically by using the clustering property of NMF. The proposed method takes advantages of the NMF in the parts-based representation and the adaptive clustering. The localized fault features of interest can be extracted as well. To evaluate the performance of the proposed method, the 9 kinds of the bearing fault on a test bench is performed. The proposed method can effectively identify the fault severity and different fault types. Moreover, in comparison with the artificial neural network(ANN), NMF yields 99.3% mean accuracy which is much superior to ANN. This research presents a simple and practical resolution for the fault diagnosis problem of rolling element bearing in high dimensional feature space.

  6. Slip rate on the Dead Sea transform fault in northern Araba valley (Jordan)

    NASA Astrophysics Data System (ADS)

    Klinger, Y.; Avouac, J. P.; Abou Karaki, N.; Dorbath, L.; Bourles, D.; Reyss, J. L.

    2000-09-01

    The Araba valley lies between the southern tip of the Dead Sea and the Gulf of Aqaba. This depression, blanketed with alluvial and lacustrine deposits, is cut along its entire length by the Dead Sea fault. In many places the fault is well defined by scarps, and evidence for left-lateral strike-slip faulting is abundant. The slip rate on the fault can be constrained from dated geomorphic features displaced by the fault. A large fan at the mouth of Wadi Dahal has been displaced by about 500m since the bulk of the fanglomerates were deposited 77-140kyr ago, as dated from cosmogenic isotope analysis (10Be in chert) of pebbles collected on the fan surface and from the age of transgressive lacustrine sediments capping the fan. Holocene alluvial surfaces are also clearly offset. By correlation with similar surfaces along the Dead Sea lake margin, we propose a chronology for their emplacement. Taken together, our observations suggest an average slip rate over the Late Pleistocene of between 2 and 6mmyr-1, with a preferred value of 4mmyr-1. This slip rate is shown to be consistent with other constraints on the kinematics of the Arabian plate, assuming a rotation rate of about 0.396°Myr-1 around a pole at 31.1°N, 26.7°E relative to Africa.

  7. Identification of faults through wavelet transform vis-à-vis fast Fourier transform of noisy vibration signals emanated from defective rolling element bearings

    NASA Astrophysics Data System (ADS)

    Paliwal, Deepak; Choudhur, Achintya; Govandhan, T.

    2014-06-01

    Fault diagnosis of rolling element bearings requires efficient signal processing techniques. For this purpose, the performances of envelope detection with fast Fourier transform (FFT) and continuous wavelet transform (CWT) of vibration signals produced from a bearing with defects on inner race and rolling element, have been examined at low signal to noise ratio. Both simulated and experimental signals from identical bearings have been considered for the purpose of analysis. The bearings have been modeled as spring-mass-dashpot systems and the simulated signals have been obtained considering transfer functions for the bearing systems subjected to impulsive loads due to the defects. Frequency B spline wavelets have been applied for CWT and a discussion on wavelet selection has been presented for better effectiveness. Results show that use of CWT with the proposed wavelets overcomes the short coming of FFT while processing a noisy vibration signals for defect detection of bearings.

  8. Fault kinematics of the Magallanes-Fagnano fault system, southern Chile; an example of diffuse strain and sinistral transtension along a continental transform margin

    NASA Astrophysics Data System (ADS)

    Betka, Paul; Klepeis, Keith; Mosher, Sharon

    2016-04-01

    A system of left-lateral faults that separates the South American and Scotia plates, known as the Magallanes-Fagnano fault system, defines the modern tectonic setting of the southernmost Andes and is superimposed on the Late Cretaceous - Paleogene Patagonian fold-thrust belt. Fault kinematic data and crosscutting relationships from populations of thrust, strike-slip and normal faults from Peninsula Brunswick adjacent to the Magallanes-Fagnano fault system, presented herein, show kinematic and temporal relationships between thrust faults and sets of younger strike-slip and normal faults. Thrust fault kinematics are homogeneous in the study area and record subhorizontal northeast-directed shortening. Strike-slip faults record east-northeast-directed horizontal shortening, west-northwest-directed horizontal extension and form Riedel and P-shear geometries compatible with left-lateral slip on the main splay of the Magallanes-Fagnano fault system. Normal faults record north-south trending extension that is compatible with the strike-slip faults. The study area occurs in a releasing step-over between overlapping segments of the Magallanes-Fagnano fault system, which localized on antecedent sutures between basement terranes with differing geological origin. Results are consistent with regional tectonic models that suggest sinistral shearing and transtension in the southernmost Andes was contemporaneous with the onset of seafloor spreading in the Western Scotia Sea during the Early Miocene.

  9. Characterization of gear faults in variable rotating speed using Hilbert-Huang Transform and instantaneous dimensionless frequency normalization

    NASA Astrophysics Data System (ADS)

    Wu, T. Y.; Chen, J. C.; Wang, C. C.

    2012-07-01

    The objective of this research is to investigate the feasibility of utilizing the instantaneous dimensionless frequency (DLF) normalization and Hilbert-Huang Transform (HHT) to characterize the different gear faults in case of variable rotating speed. The normalized DLF of the vibration signals are calculated based on the rotating speed of shaft and the instantaneous frequencies of Intrinsic Mode Functions (IMFs) which are decomposed by Empirical Mode Decomposition (EMD) process. The faulty gear features on DLF-energy distribution of vibration signal can be extracted without the presence of shaft rotating speed, so that the proposed approach can be applied for characterizing the malfunctions of gearbox system under variable shaft rotating speed. A test rig of gear transmission system is performed to illustrate the gear faults, including worn tooth, broken tooth and gear unbalance. Different methods to determine the instantaneous frequency are employed to verify the consistence of characterization results. The DLF-energy distributions of vibration signals are investigated in different faulty gear conditions. The analysis results demonstrate the capability and effectiveness of the proposed approach for characterizing the gear malfunctions at the DLFs corresponding to the meshing frequency as well as the shaft rotating frequency. The support vector machine (SVM) is then employed to classify the vibration patterns of gear transmission system at different malfunctions. Using the energy distribution at the characteristic DLFs as the features, the different fault types of gear can be identified by SVM with high accuracy.

  10. Paleoseismic observations of an onshore transform boundary: The Magallanes-Fagnano fault, Tierra del Fuego, Argentina

    USGS Publications Warehouse

    Costa, C.H.; Smalley, R.; Schwartz, D.P.; Stenner, H.D.; Ellis, M.; Ahumada, E.A.; Velasco, M.S.

    2006-01-01

    We present preliminary information on the geomorphologic features and paleoseismic record associated with the ruptures of two Ms 7.8 earthquakes that struck Tierra del Fuego and the southernmost continental margin of South America on December 17, 1949. The fault scarp was surveyed in several places cast of Lago Fagnano and a trench across a secondary fault trace of the Magallanes-Fagnano fault was excavated at the Ri??o San Pablo. The observed deformation in a 9 kyr-old peat bog sequence suggests evidence for two, and possibly three pre-1949 paleoearthquakes is preserved in the stratigraphy. The scarp reaches heights up to 11 m in late Pleistocene-Holocence(?) deposits, but the vertical component of the 1949 events was always less than ???1 m. This observation also argues for the occurrence of previous events during the Quaternary. Along die part of the fault we investigated east of Lago Fagnano, the horizontal component of the 1949 rupture does not exceed 4 m and is likely lower than 0.4 m, which is consistent with the kinematics of a local releasing bend, or at the end of a strike-slip rupture zone. ?? 2006 Revista de la Asociacio??n Geolo??gica Argentina.

  11. Lineament Domain of Regional Strike-Slip Corridor: Insight from the Neogene Transtensional De Geer Transform Fault in NW Spitsbergen

    NASA Astrophysics Data System (ADS)

    Cianfarra, P.; Salvini, F.

    2015-05-01

    Lineaments on regional scale images represent controversial features in tectonic studies. Published models explain the presence of the lineament domains in most geodynamic environments as resulting from the enhanced erosion along strikes normal to the upper crustal regional extension. Despite their success in many tectonic frameworks, these models fail to explain the existing lineament domains in the regional strike-slip corridors that separate regional blocks, including the transform faults. The present paper investigates the lineament distribution in such environments, and specifically presents the results from a study along the shear corridor of the De Geer Transform Fault in the North Atlantic, responsible for the separation and drifting away between Northern Greenland and the Svalbard Archipelago since Oligocene times. The study spans from satellite image analysis and outcrop scale investigations to a more regional analysis on a digital bathymetric model of the North Atlantic-Arctic Ocean. Lineaments were automatically detected in the spectral band 8 (0.52-0.9 μm) of a Landsat 7 image (15 m/pixel resolution). A total of 320 image lineaments were extracted from both the regional and the local scale investigations and statistically analyzed. Results from the multi-scalar lineament analyses revealed the existence of a main N-S lineament domain regionally persistent from the De Geer corridor to the western margin of northern Spitsbergen where it relates to the youngest, post-Oligocene, tectonics observed onshore. This is confirmed by field observations showing that the N-S faults represent the youngest brittle deformation system and systematically cut the deformations associated with the building of the Tertiary West Spitsbergen fold and thrust belt. The N-S lineament domain is the result of the activity of a larger, regional scale tectonic feature, NW-SE oriented and responsible for the localized extension within its deformation corridor, the De Geer Transform

  12. Detection of minute signs of a small fault in a periodic or a quasi-periodic signal by the harmonic wavelet transform

    NASA Astrophysics Data System (ADS)

    Inoue, Takumi; Sueoka, Atsuo; Kanemoto, Hiroyuki; Odahara, Satoru; Murakami, Yukitaka

    2007-07-01

    If a machine in operation has a fault, signs of the fault appear in the monitored signal and are usually synchronised with the operating speed. The signs are very small when the fault is at an early stage. The fast Fourier transform (FFT) is often utilised to detect these signs, but it is very difficult to detect minute signs. In this paper, harmonic wavelet transform is utilised to detect the minute signs of small faults in a monitored signal. The monitored signal of a machine element, in ordinary operation, is regarded as periodic or quasi-periodic. It is important for the effectual detection of the minute signs to reduce the obstructive noise and the end effects in the signal. The end effect is a peculiar phenomenon to wavelet transform and hampers effective detection. Useful methods to reduce the obstructive noise and the end effects are devised herein by the authors. Even if no visible information pertaining to a fault appears in the monitored waveform, the present method is able to detect a minute sign of a small fault. It is demonstrated that the present method is capable of detecting minute signs arising from slight collisions caused by a loose coupling and a fatigue crack.

  13. Investigation of the Oceanic Crust and Mantle in the Eastern Mid Atlantic Next to a Major Transform Fault (Gloria Fault) By Receiver Function Analysis

    NASA Astrophysics Data System (ADS)

    Hannemann, K.; Krueger, F.; Dahm, T.

    2014-12-01

    Within the project Deep OCean Test ARray (DOCTAR), we want to test how much we can enhance the signal to noise ratio (SNR) of teleseismic and regional events recorded at the ocean bottom by using broad band array methods. Furthermore, we want to learn more about the structure of the oceanic crust and mantle 100 km North of the Gloria Fault (major transform fault at the plate boundary between Eurasian and African plate in the Atlantic ocean). For the latter, we employ receiver functions and apparent P-wave incidence angles. We deployed 12 ocean bottom stations (OBS) as a mid aperture array (75 km) in the deep Eastern Mid Atlantic (4-6 km) in 2011. Each free fall station consists of a broad band seismometer and a hydrophone. After 10 month of recording, the stations were recovered. We use P phase and Rayleigh phase polarization to estimate the orientation of the stations. Different data quality and site effects at the stations need a careful review of the processing parameters (filter, deconvolution length) used for the calculation of the receiver functions. We defined different criteria as relative spike position within the deconvolution time window, and energy ratios of several time windows of the deconvolved traces to assess an evaluation of the receiver function quality in dependence on the used processing parameters. Additionally, we had a look at the relationship between the apparent incidence angle and the S-velocity and find that it differs for the ocean bottom in comparison to the free surface. Surprisingly, the densities of the oceanic crust and the water column, as well as the P-velocity of the water column have also an influence on the apparent incidence angle. We measured incidence angles for several events and find that the angles show a dependence on the dominant frequency of the event. By comparison with synthetic receiver functions, we find that water multiples have a small or no influence at all on the real data receiver functions. We identify the

  14. Detection of weak transient signals based on wavelet packet transform and manifold learning for rolling element bearing fault diagnosis

    NASA Astrophysics Data System (ADS)

    Wang, Yi; Xu, Guanghua; Liang, Lin; Jiang, Kuosheng

    2015-03-01

    The kurtogram-based methods have been proved powerful and practical to detect and characterize transient components in a signal. The basic idea of the kurtogram-based methods is to use the kurtosis as a measure to discover the presence of transient impulse components and to indicate the frequency band where these occur. However, the performance of the kurtogram-based methods is poor due to the low signal-to-noise ratio. As the weak transient signal with a wide spread frequency band can be easily masked by noise. Besides, selecting signal just in one frequency band will leave out some transient features. Aiming at these shortcomings, different frequency bands signal fusion is adopted in this paper. Considering that manifold learning aims at discovering the nonlinear intrinsic structure which embedded in high dimensional data, this paper proposes a waveform feature manifold (WFM) method to extract the weak signature from waveform feature space which obtained by binary wavelet packet transform. Minimum permutation entropy is used to select the optimal parameter in a manifold learning algorithm. A simulated bearing fault signal and two real bearing fault signals are used to validate the improved performance of the proposed method through the comparison with the kurtogram-based methods. The results show that the proposed method outperforms the kurtogram-based methods and is effective in weak signature extraction.

  15. An improved fault detection classification and location scheme based on wavelet transform and artificial neural network for six phase transmission line using single end data only.

    PubMed

    Koley, Ebha; Verma, Khushaboo; Ghosh, Subhojit

    2015-01-01

    Restrictions on right of way and increasing power demand has boosted development of six phase transmission. It offers a viable alternative for transmitting more power, without major modification in existing structure of three phase double circuit transmission system. Inspite of the advantages, low acceptance of six phase system is attributed to the unavailability of a proper protection scheme. The complexity arising from large number of possible faults in six phase lines makes the protection quite challenging. The proposed work presents a hybrid wavelet transform and modular artificial neural network based fault detector, classifier and locator for six phase lines using single end data only. The standard deviation of the approximate coefficients of voltage and current signals obtained using discrete wavelet transform are applied as input to the modular artificial neural network for fault classification and location. The proposed scheme has been tested for all 120 types of shunt faults with variation in location, fault resistance, fault inception angles. The variation in power system parameters viz. short circuit capacity of the source and its X/R ratio, voltage, frequency and CT saturation has also been investigated. The result confirms the effectiveness and reliability of the proposed protection scheme which makes it ideal for real time implementation. PMID:26435897

  16. The seismic velocity structure of a foreshock zone on an oceanic transform fault: Imaging a rupture barrier to the 2008 Mw 6.0 earthquake on the Gofar fault, EPR

    NASA Astrophysics Data System (ADS)

    Roland, E. C.; McGuire, J. J.; Lizarralde, D.; Collins, J. A.

    2010-12-01

    East Pacific Rise (EPR) oceanic transform faults are known to exhibit a number of unique seismicity characteristics, including abundant seismic swarms, a prevalence of aseismic slip, and high rates of foreshock activity. Until recently the details of how this behavior fits into the seismic cycle of large events that occur periodically on transforms have remained poorly understood. In 2008 the most recent seismic cycle of the western segment (G3) of the Gofar fault (4 degrees South on the EPR) ended with a Mw 6.0 earthquake. Seismicity associated with this event was recorded by a local array of ocean bottom seismometers, and earthquake locations reveal several distinct segments with unique slip behavior on the G3 fault. Preceding the Mw 6.0 event, a significant foreshock sequence was recorded just to the east of the mainshock rupture zone that included more than 20,000 detected earthquakes. This foreshock zone formed the eastern barrier to the mainshock rupture, and following the mainshock, seismicity rates within the foreshock zone remained unchanged. Based on aftershock locations of events following the 2007 Mw 6.0 event that completed the seismic cycle on the eastern end of the G3 fault, it appears that the same foreshock zone may have served as the western rupture barrier for that prior earthquake. Moreover, mainshock rupture associated with each of the last 8 large (~ Mw 6.0) events on the G3 fault seems to terminate at the same foreshock zone. In order to elucidate some of the structural controls on fault slip and earthquake rupture along transform faults, we present a seismic P-wave velocity profile crossing the center of the foreshock zone of the Gofar fault, as well as a profile for comparison across the neighboring Quebrada fault. Although tectonically similar, Quebrada does not sustain large earthquakes and is thought to accommodate slip primarily aseismically and with small magnitude earthquake swarms. Velocity profiles were obtained using data collected

  17. Seismic velocity constraints on the material properties that control earthquake behavior at the Quebrada-Discovery-Gofar transform faults, East Pacific Rise

    NASA Astrophysics Data System (ADS)

    Roland, Emily; Lizarralde, Dan; McGuire, Jeffrey J.; Collins, John A.

    2012-11-01

    Mid-ocean ridge transform faults (RTFs) vary strongly along strike in their ability to generate large earthquakes. This general observation suggests that local variations in material properties along RTFs exert a primary control on earthquake rupture dynamics. We explore these relationships by examining the seismic structure of two RTFs that have distinctly different seismic coupling. We determine the seismic velocity structure at the Gofar and Quebrada faults on the East Pacific Rise (EPR) using P wave traveltime tomography with data from two active-source wide-angle refraction lines crossing the faults. We image low-velocity zones (LVZs) at both faults, where P wave velocities are reduced by as much as 0.5-1.0 km/s (˜10-20%) within a several kilometer wide region. At the Gofar fault, the LVZ extends through the entire crust, into the seismogenic zone. We rule out widespread serpentinization as an explanation for the low velocities, owing to the lack of a corresponding signal in the locally measured gravity field. The reduced velocities can be explained if the plate boundary region is composed of fault material with enhanced fluid-filled porosity (1.5-8%). Local seismic observations indicate that the high-porosity region lies within a ˜10 km long portion of the fault that fails in large swarms of microearthquakes and acts as a barrier to the propagation of large (M ˜ 6.0) earthquakes. Tomographic images of fault structure combined with observed earthquake behavior suggest that EPR transform segments capable of generating large earthquakes have relatively intact gabbro within the seismogenic zone, whereas segments that slip aseismically or via earthquake swarms are composed of highly fractured, ≥2 km wide damage zones that extend throughout the crust.

  18. Ages of pre-rift basement and synrift rocks along the conjugate rift and transform margins of the Argintine Precordillera and Laurentia

    USGS Publications Warehouse

    Thomas, William A.; Tucker, Robert D.; Astini, Ricardo A.; Denison, Rodger E.

    2012-01-01

    New geochronologic data from basement rocks support the interpretation that the Argentine Precordillera (Cuyania) terrane was rifted from the Ouachita embayment of the Iapetan margin of Laurentia. New data from the Ozark dome show a range of ages in two groups at 1466 ± 3 to 1462 ± 1 Ma and 1323 ± 2 to 1317 ± 2 Ma, consistent with existing data for the Eastern Granite-Rhyolite province and Southern Granite-Rhyolite province, respectively. Similarly, a newly determined age of 1364 ± 2 Ma for the Tishomingo Granite in the Arbuckle Mountains confirms previously published analyses for this part of the Southern Granite-Rhyolite province. Along with previously reported ages from basement olistoliths in Ordovician slope deposits in the Ouachita embayment, the data for basement ages support the interpretation that rocks of the Southern Granite-Rhyolite province form the margin of Laurentian crust around the corner of the Ouachita embayment, which is bounded by the Ouachita rift and Alabama-Oklahoma transform fault. In contrast, both west and east of the corner of the Ouachita embayment, Grenville-Llano basement (approximately 1325–1000 Ma) forms the rifted margin of Laurentia. New U/Pb zircon data from basement rocks in the southern part of the Argentine Precordillera indicate crystallization ages of 1205 ± 1 Ma and 1204 ± 2 Ma, consistent with previously reported ages (approximately 1250–1000 Ma) of basement rocks from other parts of the Precordillera. These data document multiple events within the same time span as multiple events in the Grenville orogeny in eastern Laurentia, and are consistent with Grenville-age rocks along the conjugate margins of the Precordillera and Laurentia. Ages from one newly analyzed collection, however, are older than those from other basement rocks in the Precordillera. These ages, from granodioritic-granitic basement clasts in a conglomerate olistolith in Ordovician slope deposits, are 1370 ± 2 Ma and 1367 ± 5 Ma. These older

  19. Seismic constraints on a large dyking event and initiation of a transform fault zone in Western Gulf of Aden

    NASA Astrophysics Data System (ADS)

    Ahmed, AbdulHakim; Doubre, Cecile; Leroy, Sylvie; Perrot, Julie; Audin, Laurence; Rolandone, Frederique; Keir, Derek; Al-Ganad, Ismael; Sholan, Jamal; Khanbari, Khaled; Mohamed, Kassim; Vergne, Jerome; Jacques, Eric; Nercessian, Alex

    2013-04-01

    that the geodetic moment is one order of magnitude higher than the seismic moment during such events, the seismic activity of this event of the Aden ridge represents a major rifting episode certainly associated with the opening of the segment by dyking estimated to be higher than 10 m. Several computed focal mechanisms are dextral strike-slip in the western part of the dyking area could be related to a nascent transform fault zone.

  20. Detection of and response to a probable volcanogenic T-wave event swarm on the western Blanco Transform Fault Zone

    USGS Publications Warehouse

    Dziak, R.P.; Fox, C.G.; Embley, R.W.; Lupton, J.E.; Johnson, G.C.; Chadwick, W.W.; Koski, R.A.

    1996-01-01

    The East Blanco Depression (EBD), a pull-apart basin within the western Blanco Transform Fault Zone (BTFZ), was the site of an intense earthquake T-wave swarm that began at 1317Z on January 9, 1994. Although tectonically generated earthquakes occur frequently along the BTFZ, this swarm was unusual in that it was preceded and accompanied by periodic, low-frequency, long-duration acoustic signals, that originated from near the swarm epicenters. These tremor-like signals were very similar in character to acoustic energy produced by a shallow-submarine eruption near Socorro Island, a seamount several hundred km west of Baja, California. The ???69 earthquakes and ???400 tremor-like events at the EBD occurred sporadically, with two periods of peak activity occurring between January 5-16 and 27-31. The swarm-like character of the earthquakes and the similarity of the tremor activity to the Socorro eruption indicated that the EBD was undergoing an intrusion or eruption episode. On January 27, six CTD/rosette casts were conducted at the site. Water samples from two of the stations yielded anomalous 3He concentrations, with maxima at ???2800 m depth over the main basin. In June 1994 two camera tows within the basin yielded evidence of pillow-lava volcanism and hydrothermal deposits, but no conclusive evidence of a recent seafloor eruption. In September 1994, deployments of the U.S. Navy's Advanced Tethered Vehicle resulted in the discovery of an active hydrothermal mound on the flanks of a pillow-lava volcano. The hydrothermal mound consists of Fe-rich hydrothermal precipitate and bacterial mats. Temperatures to 60??C were measured 30 cm below the surface. This is the first discovery of active hydrothermal vents along an oceanic fracture zone. Although no conclusive evidence of volcanic activity associated with the T-wave event swarm was found during these response efforts, the EBD has been the site of recent seafloor eruptions. Copyright 1996 by the American Geophysical

  1. Bearing fault diagnosis under variable rotational speed via the joint application of windowed fractal dimension transform and generalized demodulation: A method free from prefiltering and resampling

    NASA Astrophysics Data System (ADS)

    Shi, Juanjuan; Liang, Ming; Guan, Yunpeng

    2016-02-01

    The conventional way for bearing fault diagnosis under variable rotational speed generally includes prefiltering, resampling based on shaft rotating frequency and order spectrum analysis. However, its application is confined by three major obstacles: a) knowledge-demanding parameter determination required by prefiltering, b) unavailable shaft rotating frequency for resampling as it is coupled with instantaneous fault characteristic frequency (IFCF) by a fault characteristic coefficient (FCC) which cannot be decided without knowing what fault actually exists, and c) complicated and error-prone resampling process. As such, we propose a new method to address these problems. The proposed method free from prefiltering and resampling mainly contains the following steps: a) extracting envelope by windowed fractal dimension (FD) transform, requiring no prefiltering, b) with the envelope signal, performing short time Fourier transform (STFT) to get a clear time frequency representation (TFR), from which the IFCF and the basic demodulator for generalized demodulation (GD) can be obtained, c) applying the generalized demodulation to the envelope signal with the current demodulator, converting the trajectory of the current time-frequency component into a linear path parallel to the time axis, d) frequency analyzing the demodulated signal, followed by searching the amplitude of the constant frequency where the linear path is situated. Updating demodulator via multiplying the basic demodulator by different real numbers (i.e., coefficient λ) and repeating the steps (c)-(d), the resampling-free order spectrum is then obtained. Based on the resulting spectrum, the final diagnosis decision can be made. The proposed method for its implementation on the example of simulated data is presented. Finally, experimental data are employed to validate the effectiveness of the proposed technique.

  2. Precarious rock and overturned transformer evidence for ground shaking in the Ms 7.7 Kern County earthquake: An analog for disastrous shaking from a major thrust fault in the Los Angeles basin

    USGS Publications Warehouse

    Brune, J.N.; Anooshehpoor, A.; Shi, B.; Zheng, Yen

    2004-01-01

    Precariously balanced rocks and overturned transformers in the vicinity of the White Wolf fault provide constraints on ground motion during the 1952 Ms 7.7 Kern County earthquake, a possible analog for an anticipated large earthquake in the Los Angeles basin (Shaw et al., 2002; Dolan et al., 2003). On the northeast part of the fault preliminary estimates of ground motion on the footwall give peak accelerations considerably lower than predicted by standard regression curves. On the other hand, on the hanging-wall, there is evidence of intense ground shattering and lack of precarious rocks, consistent with the intense hanging-wall accelerations suggested by foam-rubber modeling, numerical modeling, and observations from previous thrust fault earthquakes. There is clear evidence of the effects of rupture directivity in ground motions on the hanging-wall side of the fault (from both precarious rocks and numerical simulations). On the southwest part of the fault, which is covered by sediments, the thrust fault did not reach the surface ("blind" thrust). Overturned and damaged transformers indicate significant transfer of energy from the hanging wall to the footwall, an effect that may not be as effective when the rupture reaches the surface (is not "blind"). Transformers near the up-dip projection of the fault tip have been damaged or overturned on both the hanging-wall and footwall sides of the fault. The transfer of energy is confirmed in a numerical lattice model and could play an important role in a similar situation in Los Angeles. We suggest that the results of this study can provide important information for estimating the effects of a large thrust fault rupture in the Los Angeles basin, specially given the fact that there is so little instrumental data from large thrust fault earthquakes.

  3. Possible Interactions between the 2012 Mw 7.8 Haida Gwaii Subduction Earthquake and the Transform Queen Charlotte Fault

    NASA Astrophysics Data System (ADS)

    Hobbs, T. E.; Cassidy, J. F.; Dosso, S. E.

    2014-12-01

    This paper examines the effect of the October 2012 Mw 7.8 Haida Gwaii earthquake on aftershock nodal planes and the neighboring Queen Charlotte Fault (QCF) through Coulomb modeling and directivity analysis. The Haida Gwaii earthquake was the largest thrust event recorded in this region and ruptured an area of ~150 by 40 km on a gently NE-dipping fault off the west coast of Moresby Island, British Columbia. It is particularly interesting as it is located just to the west of the QCF, the predominantly right-lateral strike-slip fault separating the Pacific and North American plates. The QCF was the site of the largest recorded earthquake in Canada: the 1949 Ms 8.1 strike-slip earthquake whose rupture extended as far south as this 2012 event and roughly as far north as an Mw7.5 strike slip event at Craig, Alaska, which occurred just two months later in January 2013. The 75 km long portion of the QCF south of the 1949 rupture has not had a large (M ≥ 7) earthquake in over 116 years, representing a significant seismic gap. Coulomb stress transfer analysis is performed using finite fault models which incorporate seismic and geodetic data. Static stress changes are projected onto aftershock nodal planes and the QCF, including an inferred southern seismic gap. We find up to 86% of aftershocks are consistent with triggering, and as high as 96% for normal faulting events. The QCF experiences static stress changes greater than the empirically-determined threshold for triggering, with positive stress changes predicted for roughly half of the seismic gap region. Added stress from the mainshock and a lack of post-mainshock events make this seismic gap a likely location for future earthquakes. Empirical Green's function and directivity analyses are also performed to constrain rupture kinematics of the mainshock using systematic azimuthal variations in relative source time functions. Results indicate rupture progressed mainly to the northwest within 15o of the direction of the

  4. The Mw6.5 earthquake of 17 November 2015 in Lefkada Island and the seismotectonics in the Cephalonia Transform Fault (Ionian Sea, Greece)

    NASA Astrophysics Data System (ADS)

    Papadopoulos, Gerassimos A.; Agalos, Apostolos; Bocchini, Gian Maria; Chousianitis, Konstantinos; Karastathis, Vassilis; Triantafyllou, Ioanna; Kontoes, Charis; Papoutsis, Ioannis; Svigkas, Nikos; Koukouvelas, Ioannis; Zygouri, Vasiliki; Tselentis, Akis

    2016-04-01

    inversion method, which is capable of estimating the distributions of both the spatial slip and rise time on the ruptured fault, was applied using the Harvard CMT focal mechanism solution. The above velocity model was used to create the subfault synthetics. It was found that the earthquake had a not very complex source time function with nearly 78 cm maximum slip with source duration of ~13 s. Most of the slip is concentrated on a 14 km x 7 km fault rupture. The rupture propagated from the mainshock focal depth of 12 km upwards and southwards. Taking into account together the Cephalonia Jan.-Febr. 2014 seismic sequence and the Lefkada 2015 sequence, the overall seismotectonic picture is that the northern (Lefkada) branch of the Cephalonia Transform Fault (CTF) continues towards SW intersecting western Cephalonia. Also, it is likely that the 2015 earthquake fits the characteristic earthquake model suggested for the area after the 2003 Lefkada earthquake by considering also the historical seismicity of the area. This research is a contribution to the EU-FP7 ITN research project ZIP (Zooming In between Plates, grant agreement no: 604713, 2013.

  5. Constraining Earthquake Source Parameters in Rupture Patches and Rupture Barriers on Gofar Transform Fault, East Pacific Rise from Ocean Bottom Seismic Data

    NASA Astrophysics Data System (ADS)

    Moyer, P. A.; Boettcher, M. S.; McGuire, J. J.; Collins, J. A.

    2015-12-01

    On Gofar transform fault on the East Pacific Rise (EPR), Mw ~6.0 earthquakes occur every ~5 years and repeatedly rupture the same asperity (rupture patch), while the intervening fault segments (rupture barriers to the largest events) only produce small earthquakes. In 2008, an ocean bottom seismometer (OBS) deployment successfully captured the end of a seismic cycle, including an extensive foreshock sequence localized within a 10 km rupture barrier, the Mw 6.0 mainshock and its aftershocks that occurred in a ~10 km rupture patch, and an earthquake swarm located in a second rupture barrier. Here we investigate whether the inferred variations in frictional behavior along strike affect the rupture processes of 3.0 < M < 4.5 earthquakes by determining source parameters for 100 earthquakes recorded during the OBS deployment.Using waveforms with a 50 Hz sample rate from OBS accelerometers, we calculate stress drop using an omega-squared source model, where the weighted average corner frequency is derived from an empirical Green's function (EGF) method. We obtain seismic moment by fitting the omega-squared source model to the low frequency amplitude of individual spectra and account for attenuation using Q obtained from a velocity model through the foreshock zone. To ensure well-constrained corner frequencies, we require that the Brune [1970] model provides a statistically better fit to each spectral ratio than a linear model and that the variance is low between the data and model. To further ensure that the fit to the corner frequency is not influenced by resonance of the OBSs, we require a low variance close to the modeled corner frequency. Error bars on corner frequency were obtained through a grid search method where variance is within 10% of the best-fit value. Without imposing restrictive selection criteria, slight variations in corner frequencies from rupture patches and rupture barriers are not discernable. Using well-constrained source parameters, we find an

  6. TRANSFORMATION

    SciTech Connect

    LACKS,S.A.

    2003-10-09

    Transformation, which alters the genetic makeup of an individual, is a concept that intrigues the human imagination. In Streptococcus pneumoniae such transformation was first demonstrated. Perhaps our fascination with genetics derived from our ancestors observing their own progeny, with its retention and assortment of parental traits, but such interest must have been accelerated after the dawn of agriculture. It was in pea plants that Gregor Mendel in the late 1800s examined inherited traits and found them to be determined by physical elements, or genes, passed from parents to progeny. In our day, the material basis of these genetic determinants was revealed to be DNA by the lowly bacteria, in particular, the pneumococcus. For this species, transformation by free DNA is a sexual process that enables cells to sport new combinations of genes and traits. Genetic transformation of the type found in S. pneumoniae occurs naturally in many species of bacteria (70), but, initially only a few other transformable species were found, namely, Haemophilus influenzae, Neisseria meningitides, Neisseria gonorrheae, and Bacillus subtilis (96). Natural transformation, which requires a set of genes evolved for the purpose, contrasts with artificial transformation, which is accomplished by shocking cells either electrically, as in electroporation, or by ionic and temperature shifts. Although such artificial treatments can introduce very small amounts of DNA into virtually any type of cell, the amounts introduced by natural transformation are a million-fold greater, and S. pneumoniae can take up as much as 10% of its cellular DNA content (40).

  7. HOLOCENE MASS-WASTING EVENTS IN LAGO FAGNANO, TIERRA DEL FUEGO (54°S): IMPLICATIONS FOR PALEOSEISMICITY OF THE MAGALLANES-FAGNANO TRANSFORM FAULT

    NASA Astrophysics Data System (ADS)

    Ariztegui, D.; Waldmann, N.; Austin, J. A.; Anselmetti, F.; Moy, C.; Dunbar, R. B.

    2009-12-01

    High-resolution seismic imaging and sediment coring in Lago Fagnano, located along the Magallanes-Fagnano plate boundary in Tierra del Fuego, have revealed a chronologic catalog of Holocene mass-wasting events. These event layers are interpreted as resulting from slope instabilities that load the slope-adjacent lake floor during mass flow deposition thus mobilizing basin floor sediments through gravity spreading. A total of 22 mass flow deposits have been identified combining results from an 800 km-long dense grid of seismic profiles with a series of sediment cores. Successions of up to 6 m-thick mass-flow deposits pond the basin floor spreading eastward and westward following the main axis of the eastern sub-basin of Lago Fagnano. An age model on the basis of information from previous studies and from new radiocarbon dating allowed establishing a well-constrained chronologic mass-wasting event catalogue covering the last ~15000 years. Simultaneously-triggered basin-wide lateral slope failure and the formation of multiple debris flow and megaturbidite deposits are interpreted as the fingerprint of paleo-seismic activity along the Magallanes-Fagnano transform fault that runs along the entire lake basin. The slope failures and megaturbidites are interpreted as recording large earthquakes occurring along the transform fault since the early Holocene. The results from this study provide new data about the frequency and possible magnitude of Holocene earthquakes in Tierra del Fuego, which can be applied in the context of seismic hazard assessment in southernmost Patagonia.

  8. Roles of the Mendocino Transform, Vizcaino Block, and Onshore King Range Terrane in Evolution of the Northern San Andreas Fault System and Its Associated Slab Windows

    NASA Astrophysics Data System (ADS)

    McLaughlin, R. J.; Barth, G. A.; Scheirer, D. S.; Hoover, S. M.; Trehu, A. M.; Jencks, J.

    2014-12-01

    We integrate recent seismic reflection, geochemical and radiometric age data from basalts and sedimentary rocks along the Mendocino Transform (MT) and Gorda Escarpment, with basalt ages and biostratigraphy from the Miocene King Range terrane (KRT) of the Franciscan Complex, to better link the onshore and offshore geology and clarify how the northernmost San Andreas Fault (SAF) evolved. The MT extends eastward from the Gorda Ridge spreading center, along the S side of the Gorda Plate, to the edge of the North American plate (NAP) and separates the Cascadia subduction zone to the north, from the modern SAF to the south. Between 127.5º W and the shoreline, the MT and Mendocino Ridge (MR) align with the N side of the S-tilted Vizcaino structural block (VB), a remnant of NAP captured by the Pacific plate ~12 Ma, when the MT was 480 km S of its present location. The modern SAF bounds the NE-side of the VB. The SW side of the VB is bounded at the base of the continental slope by the proto-San Andreas fault (PSAF), where extinct remnants of the Pacific-Farallon ridge (PFR) interacted with the paleosubduction margin to form an incipient transform and several microplates, now part of the Pacific plate. Capture of the VB resulted from inboard breaking of the MT with a jump of the PSAF to the modern SAF. Dated ~20-12 Ma basaltic rocks from the MR between ~125º-128º W may be partly exhumed slab window underplating that formed beneath the VB during breakup of the PFR along the PSAF. High Fe and Ti relative to Mg in MR and KRT basalts, suggest eruption near ridge-transform intersections and perhaps, intratransform spreading.Onshore, high KRT relief aligns with the MR offshore. The KRT was assembled ~16-15 Ma (basalt K-Ar age; biostratigraphy); followed by its complex deformation and zeolitic metamorphism, indicating subduction to 5-8 km depth ~15-14 Ma and thermal metamorphism ~13.8 Ma (K-Ar age; vitrinite reflectance). The thermal overprint sets the KRT apart from adjacent

  9. TRANSFORMER

    DOEpatents

    Baker, W.R.

    1959-08-25

    Transformers of a type adapted for use with extreme high power vacuum tubes where current requirements may be of the order of 2,000 to 200,000 amperes are described. The transformer casing has the form of a re-entrant section being extended through an opening in one end of the cylinder to form a coaxial terminal arrangement. A toroidal multi-turn primary winding is disposed within the casing in coaxial relationship therein. In a second embodiment, means are provided for forming the casing as a multi-turn secondary. The transformer is characterized by minimized resistance heating, minimized external magnetic flux, and an economical construction.

  10. The tectonic evolution of the Mid-Atlantic Ridge between 55°55'N and the Bight Transform Fault during the past 6 Ma

    NASA Astrophysics Data System (ADS)

    Benediktsdottir, A.; Hey, R. N.; Martinez, F.; Hoskuldsson, A.

    2014-12-01

    We present a new propagating rift model of the Mid-Atlantic Ridge between 55°55'N and the Bight Transform Fault (BTF) explaining the tectonic history of the area during the past 6 Ma, using marine magnetic anomalies collected in the fall of 2013. The data consist of thirteen flowline parallel lines across the ridge and they show that the accretion across the ridge has not been symmetric. Using Magellan, a new tool to model magnetic anomalies, we obtain a tectonic evolution of the area for the past 6 Ma. The area just south of the BTF (at 0-20 km distance) is characterized by a very large asymmetry in the magnetic data. This asymmetry is most clearly seen within the Brunhes anomaly, which has a big divide in it. Our model suggests that the ridge has shifted twice some 8-12 km to the east within the past 2 Ma resulting from two very rapid rift propagations. We could not determine whether the propagations were to the south or north because of very rapid propagation rates. The tectonic evolution of the area 20-90 km south of the BTF is simpler and the model is more readily understood. The model suggests that a few short lived propagators cause asymmetry in the area. They all, but one, propagate north toward the BTF and all, but one, transfer lithosphere from the Eurasian plate to the North-American plate. Unlike the prominent far reaching (> 100km) propagators just south of Iceland these propagators are short. They play an important role in the tectonic evolution of the ridge and our results suggest that the Mid-Atlantic Ridge in this area is very dynamic.

  11. A Pore Fluid Study in the Transform Fault System of Western Haiti: Investigating Geochemical Processes and Hydrologic Pathways of the Fluids

    NASA Astrophysics Data System (ADS)

    Battani, A.; Monnin, C.; Ruffine, L.; Ellouz, N.; Leroy, S. D.

    2014-12-01

    The area of Western Haiti is located between the Enriquillo-Plantain Garden Fault (EPGF) and Ciabao-Oriente Septentrional fault systems. It has been investigated during the Haiti-SIS cruise (November-December 2012) by heat flow measurements and coring. These two strike-slip fault systems accommodate the relative motion between the Caribbean and North American plates. An aftershock study of the MW= 7, 12 January 2010 earthquake indicated that this event originated along the EPGF fault, while the septentrional fault has not been ruptured for about a century. We focused coring operations on specific zones; faults, basin margins, ridge, deep basins delimated using structural/sedimentological surface data. The objective of the pore-fluid study was to determine both the pathways of the fluids and their origin in relation with the fault activity. A total of 14 Kullenberg cores were collected for fluid sampling and sedimentological analyses. Overall, 99 pore fluids were extracted, using Rhizon® samplers. Major and minor dissolved elements were analyzed. The resulting dataset allows us to identify several diagenetic processes occurring within the upper section of the sedimentary column. For the fault-crossing zones, the vertical chloride and sulphate profiles where the dissolved-element concentrations are close to that of normal seawater suggest seawater downward flow (infiltration). There the faults would then act as recharge zones for fluid circulation. On the opposite, for cores recovered in the basins, dissolved element profiles exhibit variable shapes with sulfate concentration decreasing with depth (indicating organic matter oxydation or anaerobic oxidation of methane) These results will be combined with those from the emerged segment of the EPGF (that can be observed on land in Haiti) in order to have a picture of the hydrologic regime of the fault system, its capacity to act as a recharge zone and conversely to supply deep-seated fluids to the surface (discharge

  12. Fault finder

    DOEpatents

    Bunch, Richard H.

    1986-01-01

    A fault finder for locating faults along a high voltage electrical transmission line. Real time monitoring of background noise and improved filtering of input signals is used to identify the occurrence of a fault. A fault is detected at both a master and remote unit spaced along the line. A master clock synchronizes operation of a similar clock at the remote unit. Both units include modulator and demodulator circuits for transmission of clock signals and data. All data is received at the master unit for processing to determine an accurate fault distance calculation.

  13. Source Functions and Path Effects from Earthquakes in the Farallon Transform Fault Region, Gulf of California, Mexico that Occurred on October 2013

    NASA Astrophysics Data System (ADS)

    Castro, Raúl R.; Stock, Joann M.; Hauksson, Egill; Clayton, Robert W.

    2016-07-01

    We determined source spectral functions, Q and site effects using regional records of body waves from the October 19, 2013 (M w = 6.6) earthquake and eight aftershocks located 90 km east of Loreto, Baja California Sur, Mexico. We also analyzed records from a foreshock with magnitude 3.3 that occurred 47 days before the mainshock. The epicenters of this sequence are located in the south-central region of the Gulf of California (GoC) near and on the Farallon transform fault. This is one of the most active regions of the GoC, where most of the large earthquakes have strike-slip mechanisms. Based on the distribution of the aftershocks, the rupture propagated northwest with a rupture length of approximately 27 km. We calculated 3-component P- and S-wave spectra from ten events recorded by eleven stations of the Broadband Seismological Network of the GoC (RESBAN). These stations are located around the GoC and provide good azimuthal coverage (the average station gap is 39°). The spectral records were corrected for site effects, which were estimated calculating average spectral ratios between horizontal and vertical components (HVSR method). The site-corrected spectra were then inverted to determine the source functions and to estimate the attenuation quality factor Q. The values of Q resulting from the spectral inversion can be approximated by the relations Q_{P} = 48.1 ± 1.1 f^{0.88 ± 0.04} and Q_{S} = 135.4 ± 1.1 f^{0.58 ± 0.03} and are consistent with previous estimates reported by Vidales-Basurto et al. (Bull Seism Soc Am 104:2027-2042, 2014) for the south-central GoC. The stress drop estimates, obtained using the ω2 model, are below 1.7 MPa, with the highest stress drops determined for the mainshock and the aftershocks located in the ridge zone. We used the values of Q obtained to recalculate source and site effects with a different spectral inversion scheme. We found that sites with low S-wave amplification also tend to have low P-wave amplification, except

  14. Negligible sulfur isotope fractionation during partial melting: Evidence from Garrett transform fault basalts, implications for the late-veneer and the hadean matte

    NASA Astrophysics Data System (ADS)

    Labidi, J.; Cartigny, P.

    2016-10-01

    We report the quadruple sulfur isotope compositions, sulfur contents and speciation major and trace elements (including copper and chlorine abundances) of eleven basalts collected in the Garrett transform fault. We combine these data to discuss the absence of S isotopic fractionation along both partial melting and low-pressure fractional crystallization. The variations of K2O/TiO2 and La/SmN-ratios (respectively between 0.017 and 0.067, and between 0.31 and 0.59) suggest a range of depletion in Garrett lavas that includes ultra depleted samples (K2O/TiO2 < 0.03). The remarkable level of incompatible element depletion is consistent with re-melting of a depleted source. Contrasting with incompatible element depletion, all samples display similar S and Cu abundance (at a given major-element composition) to mid-ocean ridge basalts (MORB). This indicates that Garrett Intra Transform Lavas (ITL) are sulfide saturated as MORB are. Copper content for Garrett parental melts (MgO >8%) are ∼80 ppm, indistinguishable from MORBs. This requires their mantle sources, variably depleted in incompatible element, to host residual sulfide buffering the Cu content of all erupted melts. We calculate a minimum S content for the source of ultra-depleted Garrett lavas of 100 ± 40ppmS, i.e. roughly a factor of 2 below the MORB mantle source. After exclusion of a single sample with Cl/K ratio >0.1 that likely experienced hydrothermal sulfide assimilation, Garrett ITLs display homogeneous δ34 S, Δ33 S and Δ36 S values with averages of - 0.68 ± 0.08 ‰, + 0.010 ± 0.005 ‰ and - 0.04 ± 0.04 ‰, respectively (all 1σ, n = 10). The δ34 S values display no relationship with either K2O/TiO2 variations or extent sulfide fractionation. From these observations, we derive a 34S/32S fractionation factor between exsolved sulfides and sulfide dissolved in silicate melts of 1.0000 ± 0.0003. The S isotopic fractionation during partial melting can thus be considered as negligible, and both

  15. DIFFERENTIAL FAULT SENSING CIRCUIT

    DOEpatents

    Roberts, J.H.

    1961-09-01

    A differential fault sensing circuit is designed for detecting arcing in high-voltage vacuum tubes arranged in parallel. A circuit is provided which senses differences in voltages appearing between corresponding elements likely to fault. Sensitivity of the circuit is adjusted to some level above which arcing will cause detectable differences in voltage. For particular corresponding elements, a group of pulse transformers are connected in parallel with diodes connected across the secondaries thereof so that only voltage excursions are transmitted to a thyratron which is biased to the sensitivity level mentioned.

  16. Late Pleistocene to Holocene river terrace deformation within the Little Salmon Fault Zone: insights to tectonic transition from Cascadia Subduction to San Andreas transform stress regimes, Van Duzen river, Northern California

    NASA Astrophysics Data System (ADS)

    Nicovich, S.; Hemphill-Haley, M. A.; Leroy, T. H.

    2014-12-01

    The southern Cascadia subduction zone (CSZ) of northwestern California exhibits northeast-directed contraction, transitioning to north-northwest directed translation within the broad San Andreas fault (SAF) transform margin to the south. The Little Salmon fault (LSF) is one of the southern-most, active thrust faults within the onshore fold and thrust belt of the CSZ, and lies proximal to the transition from compressional to dextral stress across the Mendocino Triple Junction. Thus, it is an ideal location to characterize strain associated with this complex region of transitional stress regimes. High precision topographic data (LiDAR) enabled detailed mapping of geomorphic features that would otherwise be obscured by dense vegetation of the area. A northwest trending lineament, sub-parallel and south of the main splay of the LSF is observed on LiDAR imagery. The lineament exhibits potential up-to-the-northeast offset and traverses several Van Duzen river terrace risers and treads that range from Pleistocene to potentially Holocene in age. A shallow, exploratory trench was hand-excavated across the lineament. The shallow, roughly 1.5 m-deep, 16 m-long trench exposed imbricated gravels that dip into the base of the trench in the upper end. Coring within the lower end of the trench mapped the southern extent of the gravels. The architecture of the unconsolidated, clast-supported gravel deposit displays a diffuse up-to-the-northeast step. More obvious offset may be expressed at lower depths and/or in mediums with more confining stress. The linear map expression of the lineament across relatively steep terrain suggests that the fault may be relatively steeply dipping. Conjugate deformation shear bands within Neogene bedrock nearby along the Van Duzen river provide additional information about the state of stress within this area of transition.

  17. Fault diagnosis

    NASA Technical Reports Server (NTRS)

    Abbott, Kathy

    1990-01-01

    The objective of the research in this area of fault management is to develop and implement a decision aiding concept for diagnosing faults, especially faults which are difficult for pilots to identify, and to develop methods for presenting the diagnosis information to the flight crew in a timely and comprehensible manner. The requirements for the diagnosis concept were identified by interviewing pilots, analyzing actual incident and accident cases, and examining psychology literature on how humans perform diagnosis. The diagnosis decision aiding concept developed based on those requirements takes abnormal sensor readings as input, as identified by a fault monitor. Based on these abnormal sensor readings, the diagnosis concept identifies the cause or source of the fault and all components affected by the fault. This concept was implemented for diagnosis of aircraft propulsion and hydraulic subsystems in a computer program called Draphys (Diagnostic Reasoning About Physical Systems). Draphys is unique in two important ways. First, it uses models of both functional and physical relationships in the subsystems. Using both models enables the diagnostic reasoning to identify the fault propagation as the faulted system continues to operate, and to diagnose physical damage. Draphys also reasons about behavior of the faulted system over time, to eliminate possibilities as more information becomes available, and to update the system status as more components are affected by the fault. The crew interface research is examining display issues associated with presenting diagnosis information to the flight crew. One study examined issues for presenting system status information. One lesson learned from that study was that pilots found fault situations to be more complex if they involved multiple subsystems. Another was pilots could identify the faulted systems more quickly if the system status was presented in pictorial or text format. Another study is currently under way to

  18. Fault mechanics

    SciTech Connect

    Segall, P. )

    1991-01-01

    Recent observational, experimental, and theoretical modeling studies of fault mechanics are discussed in a critical review of U.S. research from the period 1987-1990. Topics examined include interseismic strain accumulation, coseismic deformation, postseismic deformation, and the earthquake cycle; long-term deformation; fault friction and the instability mechanism; pore pressure and normal stress effects; instability models; strain measurements prior to earthquakes; stochastic modeling of earthquakes; and deep-focus earthquakes. Maps, graphs, and a comprehensive bibliography are provided. 220 refs.

  19. Fault models

    NASA Astrophysics Data System (ADS)

    Sayah, H. R.; Buehler, M. G.

    1985-06-01

    A major problem in the qualification of integrated circuit cells and in the development of adequate tests for the circuits is to lack of information on the nature and density of fault models. Some of this information is being obtained from the test structures. In particular, the Pinhole Array Capacitor is providing values for the resistance of gate oxide shorts, and the Addressable Inverter Matrix is providing values for parameter distributions such as noise margins. Another CMOS fault mode, that of the open-gated transistor, is examined and the state of the transistors assessed. Preliminary results are described for a number of open-gated structures such as transistors, inverters, and NAND gates. Resistor faults are applied to various CMOS gates and the time responses are noted. The critical value for the resistive short to upset the gate response was determined.

  20. Intermittent/transient faults in digital systems

    NASA Technical Reports Server (NTRS)

    Masson, G. M.; Glazer, R. E.

    1982-01-01

    Containment set techniques are applied to 8085 microprocessor controllers so as to transform a typical control system into a slightly modified version, shown to be crashproof: after the departure of the intermittent/transient fault, return to one proper control algorithm is assured, assuming no permanent faults occur.

  1. Contemporary fault mechanics in southern Alaska

    NASA Astrophysics Data System (ADS)

    Kalbas, James L.; Freed, Andrew M.; Ridgway, Kenneth D.

    Thin-shell finite-element models, constrained by a limited set of geologic slip rates, provide a tool for evaluating the organization of contemporary faulting in southeastern Alaska. The primary structural features considered in our analysis are the Denali, Duke River, Totschunda, Fairweather, Queen Charlotte, and Transition faults. The combination of fault configurations and rheological properties that best explains observed geologic slip rates predicts that the Fairweather and Totschunda faults are joined by an inferred southeast-trending strike-slip fault that crosses the St. Elias Mountains. From a regional perspective, this structure, which our models suggest slips at a rate of ˜8 mm/a, transfers shear from the Queen Charlotte fault in southeastern Alaska and British Columbia northward to the Denali fault in central Alaska. This result supports previous hypotheses that the Fairweather-Totschunda connecting fault constitutes a newly established northward extension of the Queen Charlotte-Fairweather transform system and helps accommodate right-lateral motion (˜49 mm/a) of the Pacific plate and Yakutat microplate relative to stable North America. Model results also imply that the Transition fault separating the Yakutat microplate from the Pacific plate is favorably oriented to accommodate significant thrusting (23 mm/a). Rapid dip-slip displacement on the Transition fault does not, however, draw shear off of the Queen Charlotte-Fairweather transform fault system. Our new modeling results suggest that the Totschunda fault, the proposed Fairweather-Totschunda connecting fault, and the Fairweather fault may represent the youngest stage of southwestward migration of the active strike-slip deformation front in the long-term evolution of this convergent margin.

  2. Spontaneous rupture on irregular faults

    NASA Astrophysics Data System (ADS)

    Liu, C.

    2014-12-01

    It is now know (e.g. Robinson et al., 2006) that when ruptures propagate around bends, the rupture velocity decrease. In the extreme case, a large bend in the fault can stop the rupture. We develop a 2-D finite difference method to simulate spontaneous dynamic rupture on irregular faults. This method is based on a second order leap-frog finite difference scheme on a uniform mesh of triangles. A relaxation method is used to generate an irregular fault geometry-conforming mesh from the uniform mesh. Through this numerical coordinate mapping, the elastic wave equations are transformed and solved in a curvilinear coordinate system. Extensive numerical experiments using the linear slip-weakening law will be shown to demonstrate the effect of fault geometry on rupture properties. A long term goal is to simulate the strong ground motion near the vicinity of bends, jogs, etc.

  3. Machine learning of fault characteristics from rocket engine simulation data

    NASA Technical Reports Server (NTRS)

    Ke, Min; Ali, Moonis

    1990-01-01

    Transformation of data into knowledge through conceptual induction has been the focus of our research described in this paper. We have developed a Machine Learning System (MLS) to analyze the rocket engine simulation data. MLS can provide to its users fault analysis, characteristics, and conceptual descriptions of faults, and the relationships of attributes and sensors. All the results are critically important in identifying faults.

  4. Seismic imaging of deep low-velocity zone beneath the Dead Sea basin and transform fault: Implications for strain localization and crustal rigidity

    USGS Publications Warehouse

    ten Brink, U.S.; Al-Zoubi, A. S.; Flores, C.H.; Rotstein, Y.; Qabbani, I.; Harder, S.H.; Keller, Gordon R.

    2006-01-01

    New seismic observations from the Dead Sea basin (DSB), a large pull-apart basin along the Dead Sea transform (DST) plate boundary, show a low velocity zone extending to a depth of 18 km under the basin. The lower crust and Moho are not perturbed. These observations are incompatible with the current view of mid-crustal strength at low temperatures and with support of the basin's negative load by a rigid elastic plate. Strain softening in the middle crust is invoked to explain the isostatic compensation and the rapid subsidence of the basin during the Pleistocene. Whether the deformation is influenced by the presence of fluids and by a long history of seismic activity on the DST, and what the exact softening mechanism is, remain open questions. The uplift surrounding the DST also appears to be an upper crustal phenomenon but its relationship to a mid-crustal strength minimum is less clear. The shear deformation associated with the transform plate boundary motion appears, on the other hand, to cut throughout the entire crust. Copyright 2006 by the American Geophysical Union.

  5. Kinematic framework of the Cocos-Pacific Plate Boundary from 13°N to the Orozco TRANSFORM FAULT: RESULTS FROM AN EXTENSIVE MAGNETIC AND SEAMARC II SURVEY

    NASA Astrophysics Data System (ADS)

    Madsen, John A.; Fornari, Daniel J.; Edwards, Margo H.; Gallo, David G.; Perfit, Michael R.

    1992-05-01

    During the summer of 1987, magnetic anomaly data were collected by surface ship as part of an extensive SeaMARC II investigation of the East Pacific Rise (EPR) from 13°N to the Orozco transform. The survey extended to either side of the rise axis onto seafloor at least 1.8 million years (m.y.) in age, enabling the recent evolution of the structural and kinematic framework of the plate boundary to be studied in detail. North of 13°50'N there has been a major perturbation in the evolution of the plate boundary. Swaths of lineaments that trend oblique to EPR-parallel topography form a north pointing, V-shaped discordant zone on the Pacific and Cocos plates that is broadly symmetric about the EPR axis. On the Pacific plate a zone of discordant morphology 130 km long and between 6 and 14 km wide with a structural grain that is highly oblique to the present-day spreading direction is observed on seafloor 0.9-1.8 m.y. in age. A similar but more subtle feature of the same age is also present on the Cocos plate. These zones of discordant lineaments can be correlated with changes in the magnetic lineation pattern. On the Pacific plate the disturbed zone lies between anomalies J and 2, creating greater than normal distance between the anomalies. On the Cocos plate the disturbed zone is characterized by a distinct, high-amplitude, northwestward trending magnetic anomaly. The observed structural grain and the changes in the magnetic anomaly patterns associated with the disturbed zones are very similar to those observed at propagating ridges. Based on the magnetic anomalies, a propagation rate of 10.8 cm/yr in a N10°W direction is estimated for the past 1.8 m.y. A detailed examination of the structures developed within the disturbed zone on the Pacifc plate indicates that the rift propagation in this area can best be explained by the model of Wilson (1990) which involves cyclic rift failure with inward curvature of both rift tips. Plate adjustment to the propagation event is

  6. New Geophysical Results About the Relationship Between the Reelfoot Rift and the Rifted Margin of Laurentia

    NASA Astrophysics Data System (ADS)

    Guo, L.; Keller, G. R.

    2010-12-01

    The Reelfoot rift beneath the northern Mississippi embayment is an intracratonic graben system, which formed Early Cambrian time as a result of continental breakup, and has been subsequently reactivated by compressional or tensional stresses related to plate tectonic interactions. It strikes northeastward into the continent, and is approximately perpendicular to the rifted margin of the Laurentia that is shaped by the southeast-striking Alabama-Oklahoma transform fault. The northern section of the rift near the town of New Madrid, Missouri, was the site of three great 1811-1812 earthquakes, and it remains the most seismically active area east of the Rocky Mountains. However, the southern end of the rift is obscure, and the relationship between the Reelfoot rift and the rifted margin of Laurentia remains disputed. We analyzed the gravity and magnetic database for the region using new data enhancement techniques to shed some light on this relationship. We analyzed a large area to assess the regional geological structure. Complete Bouguer gravity data and and total magnetic intensity (TMI) data were assembled and gridded on a regular grid with spacing of 2km, the TMI data were then reduced to the magnetic pole. Then the data were processed with standard techniques to attenuate the high-frequency noise, and we analyzed the regional and residual anomalies. Specially, we calculated the tilt-angle derivatives of the data. We then calculated the directional horizontal derivatives of the tilt-angle derivatives both along and perpendicular to the strike of the rift. The maps of these derivatives clearly delineate the boundaries of the edges of the Reelfoot rift, the leading edge of the Ouachita thrust belt and the margin of Laurentia. The results of the preliminary processing indicate that the southern end of the rift is near the leading edge of the Ouachita thrust belt, which produces a more curvilinear shape for the Laurentian margin than the very linear Alabama-Oklahoma

  7. Fault-Zone Maturity Defines Maximum Earthquake Magnitude: The case of the North Anatolian Fault Zone

    NASA Astrophysics Data System (ADS)

    Bohnhoff, Marco; Bulut, Fatih; Stierle, Eva; Martinez-Garzon, Patricia; Benzion, Yehuda

    2015-04-01

    Estimating the maximum likely magnitude of future earthquakes on transform faults near large metropolitan areas has fundamental consequences for the expected hazard. Here we show that the maximum earthquakes on different sections of the North Anatolian Fault Zone (NAFZ) scale with the duration of fault zone activity, cumulative offset and length of individual fault segments. The findings are based on a compiled catalogue of historical earthquakes in the region, using the extensive literary sources that exist due to the long civilization record. We find that the largest earthquakes (M~8) are exclusively observed along the well-developed part of the fault zone in the east. In contrast, the western part is still in a juvenile or transitional stage with historical earthquakes not exceeding M=7.4. This limits the current seismic hazard to NW Turkey and its largest regional population and economical center Istanbul. Our findings for the NAFZ are consistent with data from the two other major transform faults, the San Andreas fault in California and the Dead Sea Transform in the Middle East. The results indicate that maximum earthquake magnitudes generally scale with fault-zone evolution.

  8. Saturating time-delay transformer for overcurrent protection. [Patent application

    DOEpatents

    Praeg, W.F.

    1975-12-18

    Electrical loads connected to dc supplies are protected from damage by overcurrent in the case of a load fault by connecting in series with the load a saturating transformer that detects a load fault and limits the fault current to a safe level for a period long enough to correct the fault or else disconnect the power supply.

  9. Saturating time-delay transformer for overcurrent protection

    DOEpatents

    Praeg, Walter F.

    1977-01-01

    Electrical loads connected to d-c supplies are protected from damage by overcurrent in the case of a load fault by connecting in series with the load a saturating transformer that detects a load fault and limits the fault current to a safe level for a period long enough to correct the fault or else disconnect the power supply.

  10. Fault Location Based on Synchronized Measurements: A Comprehensive Survey

    PubMed Central

    Al-Mohammed, A. H.; Abido, M. A.

    2014-01-01

    This paper presents a comprehensive survey on transmission and distribution fault location algorithms that utilize synchronized measurements. Algorithms based on two-end synchronized measurements and fault location algorithms on three-terminal and multiterminal lines are reviewed. Series capacitors equipped with metal oxide varistors (MOVs), when set on a transmission line, create certain problems for line fault locators and, therefore, fault location on series-compensated lines is discussed. The paper reports the work carried out on adaptive fault location algorithms aiming at achieving better fault location accuracy. Work associated with fault location on power system networks, although limited, is also summarized. Additionally, the nonstandard high-frequency-related fault location techniques based on wavelet transform are discussed. Finally, the paper highlights the area for future research. PMID:24701191

  11. Fault location based on synchronized measurements: a comprehensive survey.

    PubMed

    Al-Mohammed, A H; Abido, M A

    2014-01-01

    This paper presents a comprehensive survey on transmission and distribution fault location algorithms that utilize synchronized measurements. Algorithms based on two-end synchronized measurements and fault location algorithms on three-terminal and multiterminal lines are reviewed. Series capacitors equipped with metal oxide varistors (MOVs), when set on a transmission line, create certain problems for line fault locators and, therefore, fault location on series-compensated lines is discussed. The paper reports the work carried out on adaptive fault location algorithms aiming at achieving better fault location accuracy. Work associated with fault location on power system networks, although limited, is also summarized. Additionally, the nonstandard high-frequency-related fault location techniques based on wavelet transform are discussed. Finally, the paper highlights the area for future research.

  12. Arc fault detection system

    DOEpatents

    Jha, K.N.

    1999-05-18

    An arc fault detection system for use on ungrounded or high-resistance-grounded power distribution systems is provided which can be retrofitted outside electrical switchboard circuits having limited space constraints. The system includes a differential current relay that senses a current differential between current flowing from secondary windings located in a current transformer coupled to a power supply side of a switchboard, and a total current induced in secondary windings coupled to a load side of the switchboard. When such a current differential is experienced, a current travels through a operating coil of the differential current relay, which in turn opens an upstream circuit breaker located between the switchboard and a power supply to remove the supply of power to the switchboard. 1 fig.

  13. Arc fault detection system

    DOEpatents

    Jha, Kamal N.

    1999-01-01

    An arc fault detection system for use on ungrounded or high-resistance-grounded power distribution systems is provided which can be retrofitted outside electrical switchboard circuits having limited space constraints. The system includes a differential current relay that senses a current differential between current flowing from secondary windings located in a current transformer coupled to a power supply side of a switchboard, and a total current induced in secondary windings coupled to a load side of the switchboard. When such a current differential is experienced, a current travels through a operating coil of the differential current relay, which in turn opens an upstream circuit breaker located between the switchboard and a power supply to remove the supply of power to the switchboard.

  14. Pseudocolor transformation of ERTS imagery

    NASA Technical Reports Server (NTRS)

    Lamar, J. V.; Merifield, P. M.

    1973-01-01

    One of the photographic techniques which shows great promise as an aid in interpreting ERTS imagery is pseudocolor transformation. It is a process where each shade of gray in an original black-and-white image is seen as a different color in the transformation. The well known ERTS-1 MSS image of the Monterey Bay-San Francisco area was transformed using a technique which requires only two intermediate separations. Possible faults were delineated on an overlay of the transformation before referring to geologic maps. The results were quite remarkable in that all large active or recently active faults shown on the latest geologic map of California were interpreted from the image for all, or much, of their length. Perhaps the most interesting result was the Reliz fault. The fault is shown as covered; however, a lineation corresponding to the position of the fault is visible on the image. The usefulness of ERTS image in identifying recently active faults is demonstrable. Although the faults are also visible in the unenhanced image, they are clearly accentuated and more easily mapped on the pseudocolor transformation.

  15. Phase Transformations and Earthquakes

    NASA Astrophysics Data System (ADS)

    Green, H. W.

    2011-12-01

    Phase transformations have been cited as responsible for, or at least involved in, "deep" earthquakes for many decades (although the concept of "deep" has varied). In 1945, PW Bridgman laid out in detail the string of events/conditions that would have to be achieved for a solid/solid transformation to lead to a faulting instability, although he expressed pessimism that the full set of requirements would be simultaneously achieved in nature. Raleigh and Paterson (1965) demonstrated faulting during dehydration of serpentine under stress and suggested dehydration embrittlement as the cause of intermediate depth earthquakes. Griggs and Baker (1969) produced a thermal runaway model of a shear zone under constant stress, culminating in melting, and proposed such a runaway as the origin of deep earthquakes. The discovery of Plate Tectonics in the late 1960s established the conditions (subduction) under which Bridgman's requirements for earthquake runaway in a polymorphic transformation could be possible in nature and Green and Burnley (1989) found that instability during the transformation of metastable olivine to spinel. Recent seismic correlation of intermediate-depth-earthquake hypocenters with predicted conditions of dehydration of antigorite serpentine and discovery of metastable olivine in 4 subduction zones, suggests strongly that dehydration embrittlement and transformation-induced faulting are the underlying mechanisms of intermediate and deep earthquakes, respectively. The results of recent high-speed friction experiments and analysis of natural fault zones suggest that it is likely that similar processes occur commonly during many shallow earthquakes after initiation by frictional failure.

  16. Phyllosilicates formation in faults rocks: Implications for dormant fault-sealing potential and fault strength in the upper crust

    NASA Astrophysics Data System (ADS)

    Cavailhes, Thibault; Soliva, Roger; Labaume, Pierre; Wibberley, Christopher; Sizun, Jean-Pierre; Gout, Claude; Charpentier, Delphine; Chauvet, Alain; Scalabrino, Bruno; Buatier, Martine

    2013-08-01

    content and related permeability of fault zones form primary controls on hydraulic and mechanical behavior of the brittle crust. Hence, understanding and predicting the localization of these ubiquitous minerals is a major issue for fundamental and applied geosciences. We describe normal fault zones cutting a foreland arkosic turbiditic formation suffering high-T diagenesis and formed under conditions (~200°C) typical of deeply buried reservoirs and common within the seismogenic interval. Microstructural analyses show a large proportion of phyllosilicates (up to 34%) in the fault rock, derived from near-complete feldspar alteration and disaggregation during deformation. This study shows that even faults with offsets (~20 cm) much lower than bed thickness can have such large feldspar-to-phyllosilicate transformation ratios, implying that the origin of the phyllosilicates is purely transformation related. These results imply that the potential sealing capacity and strength of faults could be predicted from the host rock feldspar content. Where sealing capacity and fault strength can be related to phyllosilicate content, these properties can then also be inferred from the predicted phyllosilicate content: this opens up new horizons concerning the hydraulic and the mechanical behavior of the upper crust.

  17. Compound fault diagnosis of gearboxes based on GFT component extraction

    NASA Astrophysics Data System (ADS)

    Ou, Lu; Yu, Dejie

    2016-11-01

    Compound fault diagnosis of gearboxes is of great importance to the long-term safe operation of rotating machines, and the key is to separate different fault components. In this paper, the path graph is introduced into the vibration signal analysis and the graph Fourier transform (GFT) of vibration signals are investigated from the graph spectrum domain. To better extract the fault components in gearboxes, a new adjacency weight matrix is defined and then the GFT of simulation signals of the gear and the bearing with localized faults are analyzed. Further, since the GFT graph spectrum of the gear fault component and the bearing fault component are mainly distributed in the low-order region and the high-order region, respectively, a novel method for the compound fault diagnosis of gearboxes based on GFT component extraction is proposed. In this method, the nonzero ratios, which are introduced to analyze the eigenvectors auxiliary, and the GFT of a gearbox vibration signal, are firstly calculated. Then, the order thresholds for reconstructed fault components are determined and the fault components are extracted. Finally, the Hilbert demodulation analyses are conducted. According to the envelope spectra of the fault components, the faults of the gear and the bearing can be diagnosed respectively. The performance of the proposed method is validated by the simulation data and the experiment signals from a gearbox with compound faults.

  18. Characterization of Appalachian faults

    SciTech Connect

    Hatcher, R.D. Jr.; Odom, A.L.; Engelder, T.; Dunn, D.E.; Wise, D.U.; Geiser, P.A.; Schamel, S.; Kish, S.A.

    1988-02-01

    This study presents a classification/characterization of Appalachian faults. Characterization factors include timing of movement relative to folding, metamorphism, and plutonism; tectonic position in the orogen; relations to existing anisotropies in the rock masses; involvement of particular rock units and their ages, as well as the standard Andersonian distinctions. Categories include faults with demonstrable Cenozoic activity, wildflysch-associated thrusts, foreland bedding-plane thrusts, premetamorphic to synmetamorphic thrusts in medium- to high-grade terranes, postmetamorphic thrusts in medium- to high-grade terranes, thrusts rooted in Precambrian basement, reverse faults, strike-slip faults, normal (block) faults, compound faults, structural lineaments, faults associated with local centers of disturbance, and geomorphic (nontectonic) faults.

  19. Formal Validation of Fault Management Design Solutions

    NASA Technical Reports Server (NTRS)

    Gibson, Corrina; Karban, Robert; Andolfato, Luigi; Day, John

    2013-01-01

    The work presented in this paper describes an approach used to develop SysML modeling patterns to express the behavior of fault protection, test the model's logic by performing fault injection simulations, and verify the fault protection system's logical design via model checking. A representative example, using a subset of the fault protection design for the Soil Moisture Active-Passive (SMAP) system, was modeled with SysML State Machines and JavaScript as Action Language. The SysML model captures interactions between relevant system components and system behavior abstractions (mode managers, error monitors, fault protection engine, and devices/switches). Development of a method to implement verifiable and lightweight executable fault protection models enables future missions to have access to larger fault test domains and verifiable design patterns. A tool-chain to transform the SysML model to jpf-Statechart compliant Java code and then verify the generated code via model checking was established. Conclusions and lessons learned from this work are also described, as well as potential avenues for further research and development.

  20. Fault zone hydrogeology

    NASA Astrophysics Data System (ADS)

    Bense, V. F.; Gleeson, T.; Loveless, S. E.; Bour, O.; Scibek, J.

    2013-12-01

    Deformation along faults in the shallow crust (< 1 km) introduces permeability heterogeneity and anisotropy, which has an important impact on processes such as regional groundwater flow, hydrocarbon migration, and hydrothermal fluid circulation. Fault zones have the capacity to be hydraulic conduits connecting shallow and deep geological environments, but simultaneously the fault cores of many faults often form effective barriers to flow. The direct evaluation of the impact of faults to fluid flow patterns remains a challenge and requires a multidisciplinary research effort of structural geologists and hydrogeologists. However, we find that these disciplines often use different methods with little interaction between them. In this review, we document the current multi-disciplinary understanding of fault zone hydrogeology. We discuss surface- and subsurface observations from diverse rock types from unlithified and lithified clastic sediments through to carbonate, crystalline, and volcanic rocks. For each rock type, we evaluate geological deformation mechanisms, hydrogeologic observations and conceptual models of fault zone hydrogeology. Outcrop observations indicate that fault zones commonly have a permeability structure suggesting they should act as complex conduit-barrier systems in which along-fault flow is encouraged and across-fault flow is impeded. Hydrogeological observations of fault zones reported in the literature show a broad qualitative agreement with outcrop-based conceptual models of fault zone hydrogeology. Nevertheless, the specific impact of a particular fault permeability structure on fault zone hydrogeology can only be assessed when the hydrogeological context of the fault zone is considered and not from outcrop observations alone. To gain a more integrated, comprehensive understanding of fault zone hydrogeology, we foresee numerous synergistic opportunities and challenges for the discipline of structural geology and hydrogeology to co-evolve and

  1. Fault recovery characteristics of the fault tolerant multi-processor

    NASA Technical Reports Server (NTRS)

    Padilla, Peter A.

    1990-01-01

    The fault handling performance of the fault tolerant multiprocessor (FTMP) was investigated. Fault handling errors detected during fault injection experiments were characterized. In these fault injection experiments, the FTMP disabled a working unit instead of the faulted unit once every 500 faults, on the average. System design weaknesses allow active faults to exercise a part of the fault management software that handles byzantine or lying faults. It is pointed out that these weak areas in the FTMP's design increase the probability that, for any hardware fault, a good LRU (line replaceable unit) is mistakenly disabled by the fault management software. It is concluded that fault injection can help detect and analyze the behavior of a system in the ultra-reliable regime. Although fault injection testing cannot be exhaustive, it has been demonstrated that it provides a unique capability to unmask problems and to characterize the behavior of a fault-tolerant system.

  2. Fault-Tree Compiler

    NASA Technical Reports Server (NTRS)

    Butler, Ricky W.; Boerschlein, David P.

    1993-01-01

    Fault-Tree Compiler (FTC) program, is software tool used to calculate probability of top event in fault tree. Gates of five different types allowed in fault tree: AND, OR, EXCLUSIVE OR, INVERT, and M OF N. High-level input language easy to understand and use. In addition, program supports hierarchical fault-tree definition feature, which simplifies tree-description process and reduces execution time. Set of programs created forming basis for reliability-analysis workstation: SURE, ASSIST, PAWS/STEM, and FTC fault-tree tool (LAR-14586). Written in PASCAL, ANSI-compliant C language, and FORTRAN 77. Other versions available upon request.

  3. Termination of major strike-slip faults against thrust faults in a syntaxis, as interpreted from landsat images

    SciTech Connect

    Iranpanah, A.

    1988-01-01

    The north to northeast-striking Minab fault (Zendan fault) in western Makran, Iran, is interpreted as an intracontinental transform structure that separates, along its length, the Zagros foldbelt from the Makran active trench-arc system. The 200-km long fault has a right-lateral strike-slip component and is terminated at its northern end by the north-northwest and northwest-striking Zagros main thrust. The Minab transform zone delimits the western margin of the Makran convergence zone where an oceanic part of the Afro-Arabian lithosphere is being subducted beneath the Lut and Afghan microplates. A northern extension of the Minab transform zone terminates at an internal convergence boundary within the Bandar Abbas-Minab syntaxis. The Minab transform fault consists of a zone of generally north-northwest-trending thombic conjugate strike-slip faults. The pattern of faulting for the Minab strike-slip fault zone, when traced over the entire area on the Landsat image, shows that areas with rhombic sets of conjugate strike-slip faults are separated by a few areas showing only extensional zones. This is compatible with the traditionally idealized reverse-S pattern for the strike-slip faults reported from the United States Basin and Range province. The mechanical explanation for the rhombic pattern of the fault system is consistent with the same pattern and motion as currently exists in the Makran accretionary belt. The origin of the Bandar Abbas-Minab syntaxis is believed to be related to convergence between the Afro-Arabian plate and the Lut and Afghan microplates. The convergence zone is a well-developed trench-arc gap. The western edge of this trench-arc system has been dragged to the north along the Minab dextral fault zone. This zone, which started developing in the Late Cretaceous-Paleocene, is directly responsible for the development of the Bandar Abbas-Minab syntaxis.

  4. Fault Analysis of Space Station DC Power Systems-Using Neural Network Adaptive Wavelets to Detect Faults

    NASA Technical Reports Server (NTRS)

    Momoh, James A.; Wang, Yanchun; Dolce, James L.

    1997-01-01

    This paper describes the application of neural network adaptive wavelets for fault diagnosis of space station power system. The method combines wavelet transform with neural network by incorporating daughter wavelets into weights. Therefore, the wavelet transform and neural network training procedure become one stage, which avoids the complex computation of wavelet parameters and makes the procedure more straightforward. The simulation results show that the proposed method is very efficient for the identification of fault locations.

  5. Trishear for curved faults

    NASA Astrophysics Data System (ADS)

    Brandenburg, J. P.

    2013-08-01

    Fault-propagation folds form an important trapping element in both onshore and offshore fold-thrust belts, and as such benefit from reliable interpretation. Building an accurate geologic interpretation of such structures requires palinspastic restorations, which are made more challenging by the interplay between folding and faulting. Trishear (Erslev, 1991; Allmendinger, 1998) is a useful tool to unravel this relationship kinematically, but is limited by a restriction to planar fault geometries, or at least planar fault segments. Here, new methods are presented for trishear along continuously curved reverse faults defining a flat-ramp transition. In these methods, rotation of the hanging wall above a curved fault is coupled to translation along a horizontal detachment. Including hanging wall rotation allows for investigation of structures with progressive backlimb rotation. Application of the new algorithms are shown for two fault-propagation fold structures: the Turner Valley Anticline in Southwestern Alberta, and the Alpha Structure in the Niger Delta.

  6. FTAPE: A fault injection tool to measure fault tolerance

    NASA Technical Reports Server (NTRS)

    Tsai, Timothy K.; Iyer, Ravishankar K.

    1994-01-01

    The paper introduces FTAPE (Fault Tolerance And Performance Evaluator), a tool that can be used to compare fault-tolerant computers. The tool combines system-wide fault injection with a controllable workload. A workload generator is used to create high stress conditions for the machine. Faults are injected based on this workload activity in order to ensure a high level of fault propagation. The errors/fault ratio and performance degradation are presented as measures of fault tolerance.

  7. FTAPE: A fault injection tool to measure fault tolerance

    NASA Technical Reports Server (NTRS)

    Tsai, Timothy K.; Iyer, Ravishankar K.

    1995-01-01

    The paper introduces FTAPE (Fault Tolerance And Performance Evaluator), a tool that can be used to compare fault-tolerant computers. The tool combines system-wide fault injection with a controllable workload. A workload generator is used to create high stress conditions for the machine. Faults are injected based on this workload activity in order to ensure a high level of fault propagation. The errors/fault ratio and performance degradation are presented as measures of fault tolerance.

  8. FTAPE: A fault injection tool to measure fault tolerance

    NASA Astrophysics Data System (ADS)

    Tsai, Timothy K.; Iyer, Ravishankar K.

    1994-07-01

    The paper introduces FTAPE (Fault Tolerance And Performance Evaluator), a tool that can be used to compare fault-tolerant computers. The tool combines system-wide fault injection with a controllable workload. A workload generator is used to create high stress conditions for the machine. Faults are injected based on this workload activity in order to ensure a high level of fault propagation. The errors/fault ratio and performance degradation are presented as measures of fault tolerance.

  9. Fault-Zone Maturity Defines Maximum Earthquake Magnitude

    NASA Astrophysics Data System (ADS)

    Bohnhoff, M.; Bulut, F.; Stierle, E.; Ben-Zion, Y.

    2014-12-01

    Estimating the maximum likely magnitude of future earthquakes on transform faults near large metropolitan areas has fundamental consequences for the expected hazard. Here we show that the maximum earthquakes on different sections of the North Anatolian Fault Zone (NAFZ) scale with the duration of fault zone activity, cumulative offset and length of individual fault segments. The findings are based on a compiled catalogue of historical earthquakes in the region, using the extensive literary sources that exist due to the long civilization record. We find that the largest earthquakes (M~8) are exclusively observed along the well-developed part of the fault zone in the east. In contrast, the western part is still in a juvenile or transitional stage with historical earthquakes not exceeding M=7.4. This limits the current seismic hazard to NW Turkey and its largest regional population and economical center Istanbul. Our findings for the NAFZ are consistent with data from the two other major transform faults, the San Andreas fault in California and the Dead Sea Transform in the Middle East. The results indicate that maximum earthquake magnitudes generally scale with fault-zone evolution.

  10. Isolability of faults in sensor fault diagnosis

    NASA Astrophysics Data System (ADS)

    Sharifi, Reza; Langari, Reza

    2011-10-01

    A major concern with fault detection and isolation (FDI) methods is their robustness with respect to noise and modeling uncertainties. With this in mind, several approaches have been proposed to minimize the vulnerability of FDI methods to these uncertainties. But, apart from the algorithm used, there is a theoretical limit on the minimum effect of noise on detectability and isolability. This limit has been quantified in this paper for the problem of sensor fault diagnosis based on direct redundancies. In this study, first a geometric approach to sensor fault detection is proposed. The sensor fault is isolated based on the direction of residuals found from a residual generator. This residual generator can be constructed from an input-output or a Principal Component Analysis (PCA) based model. The simplicity of this technique, compared to the existing methods of sensor fault diagnosis, allows for more rational formulation of the isolability concepts in linear systems. Using this residual generator and the assumption of Gaussian noise, the effect of noise on isolability is studied, and the minimum magnitude of isolable fault in each sensor is found based on the distribution of noise in the measurement system. Finally, some numerical examples are presented to clarify this approach.

  11. Hypogene and supergene alteration of the zeolite-bearing pyroclastic deposits at Tell Rimah, Jordan, and rift-related processes along the Dead-Sea-Transform Fault System during the Quaternary

    NASA Astrophysics Data System (ADS)

    Dill, H. G.; Techmer, A.; Botz, R.; Dohrmann, R.; Kaufhold, S.

    2012-09-01

    The boundary between the Arabian and African plates, is marked in the Middle East by one of the most prominent deep-seated lineamentary structures, called the Dead-Sea-Transform Fault System (DSTFS). Structural and mineralogical processes related to the DSTFS were correlated with equivalent processes leading to the alteration of pyroclastic deposits of alkali-olivine basaltic to nepheline basaltic composition which formed during a time span of less than 0.5 Ma. The large deposit of Tell Rimah, Jordan, is operated for the exploitation of zeolites, tuffs, and as pozzolana raw material. Four discrete stages of mineralizations have been distinguished from each other within these volcanic-hosted mineral deposits. (1) Hypogene syneruptive alteration of pyroclastic rocks produced siliceous gels ("allophane"), smectite, analcime, and phillipsite in vesicles when the groundwater level was low in the rift basin of the DSTFS. The lake-level lowstand caused the fluid system in the pyroclastic cone to become self-sufficient and it has been considered as a closed hydrothermal system. (2) Periods of tectonic and magmatic quiescence grinded the detrital sedimentation in the rift basin to a halt, while triggering a supergene alteration in the eruptive cones on the adjacent Arabian Plate. (3) Epigenetic alteration affected the pyroclastic rocks in the distal part of the DSTFS as a result of a rising water level. The water gradually filled the pore space of the permeable pyroclastic deposits almost to completeness and caused meniscus and blocky cements of calcite, phillipsite and chabazite to develop. In the rift basin, contemporaneously with the alteration of the pyroclastic rocks, freshwater limestones formed on calcareous bedrocks. Ba and Mn minerals in these freshwater limestones were supplied by subaquatic brines. Subsequently, a drastic lowering of the lake water level in the DSTFS converted the system of subaquatic freshwater limestones into subaerial tufa and travertine. As

  12. Rolling element bearing fault diagnosis via fault characteristic order (FCO) analysis

    NASA Astrophysics Data System (ADS)

    Wang, Tianyang; Liang, Ming; Li, Jianyong; Cheng, Weidong

    2014-03-01

    Order tracking based on time-frequency representation (TFR) is one of the most effective methods for gear fault detection under time-varying rotational speed without using a tachometer. However, for a rolling element bearing, the signal components related to rotational speed usually cannot be directly extracted from the TFR. As such, we propose a new method to solve this problem. This method consists of four main steps: (a) signal filtering via fast spectral kurtosis (SK) analysis - this together with the short time Fourier transform (STFT) leads to a TFR of the filtered signal with clear fault-revealing trend lines, (b) extraction of instantaneous fault characteristic frequency (IFCF) from the TFR using an amplitude-sum based spectral peak search algorithm, (c) signal resampling based on the extracted IFCF to convert the non-stationary time-domain signal into the stationary fault phase angle (FPA) domain signal, and (d) transform of the FPA domain signal into the domain of the fault characteristic order (FCO) and identification of fault type from the FCO spectrum. The effectiveness of the proposed method has been validated by both simulated and experimental bearing vibration signals.

  13. The implication of gouge mineralogy evolution on fault creep: an example from The North Anatolian Fault, Turkey

    NASA Astrophysics Data System (ADS)

    Kaduri, M.; Gratier, J. P.; Renard, F.; Cakir, Z.; Lasserre, C.

    2015-12-01

    Aseismic creep is found along several sections of major active faults at shallow depth, such as the North Anatolian Fault in Turkey, the San Andreas Fault in California (USA), the Longitudinal Valley Fault in Taiwan, the Haiyuan fault in China and the El Pilar Fault in Venezuela. Identifying the mechanisms controlling creep and their evolution with time and space represents a major challenge for predicting the mechanical evolution of active faults, the interplay between creep and earthquakes, and the link between short-term observations from geodesy and the geological setting. Hence, studying the evolution of initial rock into damaged rock, then into gouge, is one of the key question for understanding the origin of fault creep. In order to address this question we collected samples from a dozen well-preserved fault outcrops along creeping and locked sections of the North Anatolian Fault. We used various methods such as microscopic and geological observations, EPMA, XRD analysis, combined with image processing, to characterize their mineralogy and strain. We conclude that (1) there is a clear correlation between creep localization and gouge composition. The locked sections of the fault are mostly composed of massive limestone. The creeping sections comprises clay gouges with 40-80% low friction minerals such as smectite, saponite, kaolinite, that facilitates the creeping. (2) The fault gouge shows two main structures that evolve with displacement: anastomosing cleavage develop during the first stage of displacement; amplifying displacement leads to layering development oblique or sub-parallel to the fault. (3) We demonstrate that the fault gouge result from a progressive evolution of initial volcanic rocks including dissolution of soluble species that move at least partially toward the damage zones and alteration transformations by fluid flow that weaken the gouge and strengthen the damage zone.

  14. Metamorphism, argon depletion, heat flow and stress on the Alpine fault

    NASA Technical Reports Server (NTRS)

    Scholz, C. H.; Beavan, J.; Hanks, T. C.

    1978-01-01

    The Alpine fault of New Zealand is a major continental transform fault which was uplifted on its southeast side 4 to 11 km within the last 5 m.y. This uplift has exposed the Haast schists, which were metamorphosed from the adjacent Torlesse graywackes. The Haast schists increase in metamorphic grade from prehnite-pumpellyite facies 9-12 km from the fault through the chlorite and biotite zones of the greenschist facies to the garnet-oligoclase zone amphibolite facies within 4 km of the fault. These metamorphic zone boundaries are subparallel to the fault for 350 km along the strike. The K-Ar and Rb-Sr ages of the schists increase with distance from the fault: from 4 m.y. within 3 km of the fault to approximately 110 m.y. 20 km from the fault. Field relations show that the source of heat that produced the argon depletion aureole was the fault itself.

  15. Exploring fault rocks at the nanoscale

    NASA Astrophysics Data System (ADS)

    Viti, Cecilia

    2010-05-01

    decomposition and subsequent re-crystallization of K-feldspar. The examples above show that TEM can be a powerful tool to detect deformation-induced transformations within fault rocks, often taking place at a sub-micrometer scale. These transformations include mineral reaction, decomposition and re-crystallization processes, crystal defects, preferred orientation, formation of poorly-crystalline to amorphous materials, i.e., all those features that can play a fundamental role in the mechanical behaviour of a fault rock.

  16. How Faults Shape the Earth.

    ERIC Educational Resources Information Center

    Bykerk-Kauffman, Ann

    1992-01-01

    Presents fault activity with an emphasis on earthquakes and changes in continent shapes. Identifies three types of fault movement: normal, reverse, and strike faults. Discusses the seismic gap theory, plate tectonics, and the principle of superposition. Vignettes portray fault movement, and the locations of the San Andreas fault and epicenters of…

  17. Geodynamics of the Dead Sea Fault: Do active faulting and past earthquakes determine the seismic gaps?

    NASA Astrophysics Data System (ADS)

    Meghraoui, Mustapha

    2014-05-01

    The ~1000-km-long North-South trending Dead Sea transform fault (DSF) presents structural discontinuities and includes segments that experienced large earthquakes (Mw>7) in historical times. The Wadi Araba and Jordan Valley, the Lebanese restraining bend, the Missyaf and Ghab fault segments in Syria and the Ziyaret Fault segment in Turkey display geometrical complexities made of step overs, restraining and releasing bends that may constitute major obstacles to earthquake rupture propagation. Using active tectonics, GPS measurements and paleoseismology we investigate the kinematics and long-term/short term slip rates along the DSF. Tectonic geomorphology with paleoseismic trenching and archeoseismic investigations indicate repeated faulting events and left-lateral slip rate ranging from 4 mm/yr in the southern fault section to 6 mm/yr in the northern fault section. Except for the northernmost DSF section, these estimates of fault slip rate are consistent with GPS measurements that show 4 to 5 mm/yr deformation rate across the plate boundary. However, recent GPS results showing ~2.5 mm/yr velocity rate of the northern DSF appears to be quite different than the ~6 mm/yr paleoseismic slip rate. The kinematic modeling that combines GPS and seismotectonic results implies a complex geodynamic pattern where the DSF transforms the Cyprus arc subduction zone into transpressive tectonics on the East Anatolian fault. The timing of past earthquake ruptures shows the occurrence of seismic sequences and a southward migration of large earthquakes, with the existence of major seismic gaps along strike. In this paper, we discuss the role of the DSF in the regional geodynamics and its implication on the identification of seismic gaps.

  18. Fault tectonics and earthquake hazards in parts of southern California. [penninsular ranges, Garlock fault, Salton Trough area, and western Mojave Desert

    NASA Technical Reports Server (NTRS)

    Merifield, P. M. (Principal Investigator); Lamar, D. L.; Gazley, C., Jr.; Lamar, J. V.; Stratton, R. H.

    1976-01-01

    The author has identified the following significant results. Four previously unknown faults were discovered in basement terrane of the Peninsular Ranges. These have been named the San Ysidro Creek fault, Thing Valley fault, Canyon City fault, and Warren Canyon fault. In addition fault gouge and breccia were recognized along the San Diego River fault. Study of features on Skylab imagery and review of geologic and seismic data suggest that the risk of a damaging earthquake is greater along the northwestern portion of the Elsinore fault than along the southeastern portion. Physiographic indicators of active faulting along the Garlock fault identifiable in Skylab imagery include scarps, linear ridges, shutter ridges, faceted ridges, linear valleys, undrained depressions and offset drainage. The following previously unrecognized fault segments are postulated for the Salton Trough Area: (1) An extension of a previously known fault in the San Andreas fault set located southeast of the Salton Sea; (2) An extension of the active San Jacinto fault zone along a tonal change in cultivated fields across Mexicali Valley ( the tonal change may represent different soil conditions along opposite sides of a fault). For the Skylab and LANDSAT images studied, pseudocolor transformations offer no advantages over the original images in the recognition of faults in Skylab and LANDSAT images. Alluvial deposits of different ages, a marble unit and iron oxide gossans of the Mojave Mining District are more readily differentiated on images prepared from ratios of individual bands of the S-192 multispectral scanner data. The San Andreas fault was also made more distinct in the 8/2 and 9/2 band ratios by enhancement of vegetation differences on opposite sides of the fault. Preliminary analysis indicates a significant earth resources potential for the discrimination of soil and rock types, including mineral alteration zones. This application should be actively pursued.

  19. Fault detection in rotor bearing systems using time frequency techniques

    NASA Astrophysics Data System (ADS)

    Chandra, N. Harish; Sekhar, A. S.

    2016-05-01

    Faults such as misalignment, rotor cracks and rotor to stator rub can exist collectively in rotor bearing systems. It is an important task for rotor dynamic personnel to monitor and detect faults in rotating machinery. In this paper, the rotor startup vibrations are utilized to solve the fault identification problem using time frequency techniques. Numerical simulations are performed through finite element analysis of the rotor bearing system with individual and collective combinations of faults as mentioned above. Three signal processing tools namely Short Time Fourier Transform (STFT), Continuous Wavelet Transform (CWT) and Hilbert Huang Transform (HHT) are compared to evaluate their detection performance. The effect of addition of Signal to Noise ratio (SNR) on three time frequency techniques is presented. The comparative study is focused towards detecting the least possible level of the fault induced and the computational time consumed. The computation time consumed by HHT is very less when compared to CWT based diagnosis. However, for noisy data CWT is more preferred over HHT. To identify fault characteristics using wavelets a procedure to adjust resolution of the mother wavelet is presented in detail. Experiments are conducted to obtain the run-up data of a rotor bearing setup for diagnosis of shaft misalignment and rotor stator rubbing faults.

  20. Numerical modeling of transformer inrush currents

    NASA Astrophysics Data System (ADS)

    Cardelli, E.; Faba, A.

    2014-02-01

    This paper presents an application of a vector hysteresis model to the prediction of the inrush current due the arbitrary initial excitation of a transformer after a fault. The approach proposed seems promising in order to predict the transient overshoot in current and the optimal time to close the circuit after the fault.

  1. Apparent stress, fault maturity and seismic hazard for normal-fault earthquakes at subduction zones

    USGS Publications Warehouse

    Choy, G.L.; Kirby, S.H.

    2004-01-01

    The behavior of apparent stress for normal-fault earthquakes at subduction zones is derived by examining the apparent stress (?? a = ??Es/Mo, where E s is radiated energy and Mo is seismic moment) of all globally distributed shallow (depth, ?? 1 MPa) are also generally intraslab, but occur where the lithosphere has just begun subduction beneath the overriding plate. They usually occur in cold slabs near trenches where the direction of plate motion across the trench is oblique to the trench axis, or where there are local contortions or geometrical complexities of the plate boundary. Lower ??a (< 1 MPa) is associated with events occurring at the outer rise (OR) complex (between the OR and the trench axis), as well as with intracrustal events occurring just landward of the trench. The average apparent stress of intraslab-normal-fault earthquakes is considerably higher than the average apparent stress of interplate-thrust-fault earthquakes. In turn, the average ?? a of strike-slip earthquakes in intraoceanic environments is considerably higher than that of intraslab-normal-fault earthquakes. The variation of average ??a with focal mechanism and tectonic regime suggests that the level of ?? a is related to fault maturity. Lower stress drops are needed to rupture mature faults such as those found at plate interfaces that have been smoothed by large cumulative displacements (from hundreds to thousands of kilometres). In contrast, immature faults, such as those on which intraslab-normal-fault earthquakes generally occur, are found in cold and intact lithosphere in which total fault displacement has been much less (from hundreds of metres to a few kilometres). Also, faults on which high ??a oceanic strike-slip earthquakes occur are predominantly intraplate or at evolving ends of transforms. At subduction zones, earthquakes occurring on immature faults are likely to be more hazardous as they tend to generate higher amounts of radiated energy per unit of moment than

  2. Faulted Ancient Aqueduct and Successive Displacements along the Dead Sea Fault in Syria

    NASA Astrophysics Data System (ADS)

    Sbeinat, R.; Meghraoui, M.; Gomez, F.; van der Woerd, J.; Layyous, I.; Al-Ghazzi, R.; Barazangi, M.

    2003-04-01

    We conducted a combined study in archeoseismology with detailed descriptions and mapping with a total station of a faulted ancient aqueduct, and in paleoseismology with a 15-m-long and 3.5-m-deep trench near the aqueduct and across the fault. Micro-topographic surveys and trenching show that the fault offsets left-laterally an ancient aqueduct which is repeatedly fractured and younger than BC 410. Projecting the aqueduct walls into the north-south striking DSF displays a total left-lateral displacement of 13.6 ±0.2 m between the two blocks of the faulted aqueduct. Moreover, the northern warped wall shows a deflection (with cracks and brecciated travertines below) that amount 4.3 m and can be considered as a minimum for the first left-lateral displacement. The aqueduct also displays at least two kinds of building stones suggesting rebuilding episodes. Using radiocarbon dating of faulted young alluvial deposits we document the occurrence of three large earthquakes in the past 2200 years (between BC 150 - AD 750, between AD 700 - 1030 and between AD 990 - 1210). The most recent faulting event may correspond to the well-documented large earthquake of AD 1170 for which we estimate Mw = 7.3 - 7.5. Our study provides the timing of late Holocene earthquakes and constrains the 6.9 ± 1.2 mm/yr. slip rate of the Dead Sea transform fault in northwestern Syria (the Missyaf fault segment). Reports of large earthquakes and their associated damage in the Middle East are frequently reported during the Greek, Hebrew, Assyrian, Roman, Byzantine and Islamic times. The ˜830 years of seismic quiescence along the Missyaf fault segment implies that a large earthquake is overdue and may result in a major catastrophe to the population centres of Syria and Lebanon.

  3. Solar system fault detection

    NASA Astrophysics Data System (ADS)

    Farrington, R. B.; Pruett, J. C., Jr.

    1984-05-01

    A fault detecting apparatus and method are provided for use with an active solar system. The apparatus provides an indication as to whether one or more predetermined faults have occurred in the solar system. The apparatus includes a plurality of sensors, each sensor being used in determining whether a predetermined condition is present. The outputs of the sensors are combined in a pre-established manner in accordance with the kind of predetermined faults to be detected. Indicators communicate with the outputs generated by combing the sensor outputs to give the user of the solar system and the apparatus an indication as to whether a predetermined fault has occurred. Upon detection and indication of any predetermined fault, the user can take appropriate corrective action so that the overall reliability and efficiency of the active solar system are increased.

  4. Solar system fault detection

    DOEpatents

    Farrington, Robert B.; Pruett, Jr., James C.

    1986-01-01

    A fault detecting apparatus and method are provided for use with an active solar system. The apparatus provides an indication as to whether one or more predetermined faults have occurred in the solar system. The apparatus includes a plurality of sensors, each sensor being used in determining whether a predetermined condition is present. The outputs of the sensors are combined in a pre-established manner in accordance with the kind of predetermined faults to be detected. Indicators communicate with the outputs generated by combining the sensor outputs to give the user of the solar system and the apparatus an indication as to whether a predetermined fault has occurred. Upon detection and indication of any predetermined fault, the user can take appropriate corrective action so that the overall reliability and efficiency of the active solar system are increased.

  5. Solar system fault detection

    DOEpatents

    Farrington, R.B.; Pruett, J.C. Jr.

    1984-05-14

    A fault detecting apparatus and method are provided for use with an active solar system. The apparatus provides an indication as to whether one or more predetermined faults have occurred in the solar system. The apparatus includes a plurality of sensors, each sensor being used in determining whether a predetermined condition is present. The outputs of the sensors are combined in a pre-established manner in accordance with the kind of predetermined faults to be detected. Indicators communicate with the outputs generated by combining the sensor outputs to give the user of the solar system and the apparatus an indication as to whether a predetermined fault has occurred. Upon detection and indication of any predetermined fault, the user can take appropriate corrective action so that the overall reliability and efficiency of the active solar system are increased.

  6. Hydrothermal circulation in fault slots with topography

    NASA Astrophysics Data System (ADS)

    Titarenko, Sofya; McCaig, Andrew

    2014-05-01

    There are numerous cases where the circulation of hydrothermal fluid is likely to be confined within a permeable fault slot. Examples are (1) the Lost City Hydrothermal Field (LCHF) at 30 N in the Atlantic, which is likely to be controlled by large E-W faults related to the Atlantis transform fault and mass wasting on the southern wall of the Atlantis Massif, and (2) large normal faults bounding the Hess Deep rift in the East Pacific, which contain intense hydrothermal metamorphic assemblages in lower crustal gabbros formed at 200-350 ° C. This type of circulation could occur anywhere where steep faults cut the oceanic crust, including large near-axis normal faults, transform faults and faults at subduction bend zones, and could be the major way in which the upper mantle and lower crust are hydrated. It is therefore important to constrain the controls on temperature conditions of alteration and hence mineral assemblages. Previous 2-D modelling of the LCHF shows that seafloor topography and permeability structure combine together to localise the field near the highest point of the Atlantis Massif. Our new models are 3-D, based on a 10km cube with seafloor topography of ~ 2km affecting both the fault slot and impermeable wall rocks. We have used Comsol multiphysics in this modelling, with a constant basal heatflow corresponding to the near conductive thermal gradient measured in IODP Hole 1309D, 5km north of the LCHF, and a constant temperature seafloor boundary condition. The wall rocks of the slot have a permeability of 10-17 m2 while permeability in the slot is varied between 10-14 and 10-15 m2. Initial conditions are a conductive thermal structure corresponding to the basal heatflow at steady state. Generic models not based on any particular known topography quickly stabilise a hydrothermal system in the fault slot with a single upflow zone close to the model edge with highest topography. In models with a depth of circulation in the fault slot of about 6 km

  7. Subsidence history of the Alabama promontory in response to Late Paleozoic Appalachian-Ouachita thrusting

    SciTech Connect

    Whitting, B.M.; Thomas, W.A. . Dept. of Geological Sciences)

    1994-03-01

    The Alabama promontory of North American continental crust was framed during late Precambrian-Cambrian rifting by the northeast-striking Blue Ridge rift and the northwest-striking alabama-Oklahoma transform fault. A passive margin persisted along the western side of the promontory from Cambrian to Mississippian time, but the eastern side was affected by the Taconic and Acadian orogenies. Prior to initiation of Ouachita and Appalachian (Alleghanian) thrusting, the outline of the rifted margin of continental crust on the Alabama promontory remained intact; and the late paleozoic thrust belt conformed to the shape of the promontory, defining northwest-striking Ouachita thrust faults along the southwest side of the promontory, north-striking Appalachian (Georgia-Tennessee) thrust faults on the east, and northeast-striking Appalachian (Alabama) thrust faults across the corner of the promontory. Subsidence profiles perpendicular to each of the strike domains of the thrust belt have been constructed by calculating total subsidence from decompacted thickness of the synorogenic sedimentary deposits. The profile perpendicular to the Ouachita thrust belt shows increasing subsidence rates through time and toward the thrust front, indicating the classic signature of an orogenic foreland basin. The profile perpendicular to the Georgia-Tennessee Appalachian thrust belt similarly shows increasing subsidence rates through time and toward the orogenic hinterland. These quantitative results support the conclusion that Black Warrior basin subsidence is tectonically rather than sedimentologically driven, and the timing of subsidence events reported here has implications for regional tectonic models.

  8. Pseudotachylyte-bearing faults and shear zones along the Norumbega fault system in Maine

    NASA Astrophysics Data System (ADS)

    West, D. P.; Price, N. A.; Swanson, M.; Pollock, S. G.

    2012-12-01

    The Norumbega fault system represents the eroded roots of a >400 km long fault system that records a Middle Paleozoic through Mesozoic history of superimposed deformational processes. The Paleozoic history is dominated by right lateral shearing that evolved from a wide zone of regional scale dextral transpression to more highly focused and in many cases seismogenic slip along relatively narrow faults and shear zones. The Mesozoic history, largely deduced through geochronological studies, likely involved localized reactivation in association with the transition between Late Paleozoic dextral transpression and Early Mesozoic extension in the northern Appalachians. Pseudotachylyte, found in a variety of structural settings, has been identified on numerous fault strands along the southern 250 km of the fault system in Maine and provides an excellent opportunity to evaluate evolving seismogenic processes, at a variety of depths, along a regional scale fault system. The oldest pseudotachylyte (Late Devonian-Early Carboniferous) formed at frictional-to-viscous transitional depths during dextral deformation and is most commonly characterized by multiple generations of foliation-parallel frictional melt veins that were subsequently deformed through viscous shearing and transformed into thin ultramylonite layers. While this variety of pseudotachylyte has only been positively identified along three ~25 km long fault segments within the central portion of the Norumbega (e.g., Sandhill Corner), we speculate it may be more widespread in the fault system owing to difficulties in recognition in the field and a lack of detailed imaging and laboratory studies of mylonite-hosted pseudotachylyte-bearing rocks in the fault system. Younger (Permian-Early Triassic) undeformed pseudotachylyte-bearing faults have been found discontinuously along much of the Norumbega and presumably these occurrences reflect countless high velocity coseismic slip events at shallower depths. Spectacularly

  9. Fault Detection in Differential Algebraic Equations

    NASA Astrophysics Data System (ADS)

    Scott, Jason Roderick

    Fault detection and identification (FDI) is important in almost all real systems. Fault detection is the supervision of technical processes aimed at detecting undesired or unpermitted states (faults) and taking appropriate actions to avoid dangerous situations, or to ensure efficiency in a system. This dissertation develops and extends fault detection techniques for systems modeled by differential algebraic equations (DAEs). First, a passive, observer-based approach is developed and linear filters are constructed to identify faults by filtering residual information. The method presented here uses the least squares completion to compute an ordinary differential equation (ODE) that contains the solution of the DAE and applies the observer directly to this ODE. While observers have been applied to ODE models for the purpose of fault detection in the past, the use of observers on completions of DAEs is a new idea. Moreover, the resulting residuals are modified requiring additional analysis. Robustness with respect to disturbances is also addressed by a novel frequency filtering technique. Active detection, as opposed to passive detection where outputs are passively monitored, allows the injection of an auxiliary control signal to test the system. These algorithms compute an auxiliary input signal guaranteeing fault detection, assuming bounded noise. In the second part of this dissertation, a novel active detection approach for DAE models is developed by taking linear transformations of the DAEs and solving a bi-layer optimization problem. An efficient real-time detection algorithm is also provided, as is the extension to model uncertainty. The existence of a class of problems where the algorithm breaks down is revealed and an alternative algorithm that finds a nearly minimal auxiliary signal is presented. Finally, asynchronous signal design, that is, applying the test signal on a different interval than the observation window, is explored and discussed.

  10. Engine Fault Diagnosis using DTW, MFCC and FFT

    NASA Astrophysics Data System (ADS)

    Singh, Vrijendra; Meena, Narendra

    . In this paper we have used a combination of three algorithms: Dynamic time warping (DTW) and the coefficients of Mel frequency Cepstrum (MFC) and Fast Fourier Transformation (FFT) for classifying various engine faults. Dynamic time warping and MFCC (Mel Frequency Cepstral Coefficients), FFT are used usually for automatic speech recognition purposes. This paper introduces DTW algorithm and the coefficients extracted from Mel Frequency Cepstrum, FFT for automatic fault detection and identification (FDI) of internal combustion engines for the first time. The objective of the current work was to develop a new intelligent system that should be able to predict the possible fault in a running engine at different-different workshops. We are doing this first time. Basically we took different-different samples of Engine fault and applied these algorithms, extracted features from it and used Fuzzy Rule Base approach for fault Classification.

  11. Measuring fault tolerance with the FTAPE fault injection tool

    NASA Technical Reports Server (NTRS)

    Tsai, Timothy K.; Iyer, Ravishankar K.

    1995-01-01

    This paper describes FTAPE (Fault Tolerance And Performance Evaluator), a tool that can be used to compare fault-tolerant computers. The major parts of the tool include a system-wide fault-injector, a workload generator, and a workload activity measurement tool. The workload creates high stress conditions on the machine. Using stress-based injection, the fault injector is able to utilize knowledge of the workload activity to ensure a high level of fault propagation. The errors/fault ratio, performance degradation, and number of system crashes are presented as measures of fault tolerance.

  12. Measuring fault tolerance with the FTAPE fault injection tool

    NASA Astrophysics Data System (ADS)

    Tsai, Timothy K.; Iyer, Ravishankar K.

    1995-05-01

    This paper describes FTAPE (Fault Tolerance And Performance Evaluator), a tool that can be used to compare fault-tolerant computers. The major parts of the tool include a system-wide fault-injector, a workload generator, and a workload activity measurement tool. The workload creates high stress conditions on the machine. Using stress-based injection, the fault injector is able to utilize knowledge of the workload activity to ensure a high level of fault propagation. The errors/fault ratio, performance degradation, and number of system crashes are presented as measures of fault tolerance.

  13. Complex Rift-Parallel, Strike-Slip Faulting in Iceland: Kinematic Analysis of the Gljúfurá Fault Zone

    NASA Astrophysics Data System (ADS)

    Nanfito, A.; Karson, J. A.

    2009-12-01

    strike of the fault zone and cut across the deformation fabrics. Although no features could be correlated across the fault zone to constrain the lateral displacement, empirical gouge thickness/displacement scaling relationships suggest at least several kilometers of slip. Previous studies interpreted the Gljúfurá Fault Zone was one of a family of parallel, strike-slip “bookshelf” faults associated with a transform fault zone linking two now-extinct rifts. Unlike the well-known rift-parallel, strike-slip faults of the South Iceland Seismic Zone and the Tjornes Fracture Zone, the Gljúfurá Fault Zone appears to be an isolated structure with substantially larger displacement that is discordant with surrounding basement lineaments. Major strike-slip faults of this kind can provide important clues in the reconstruction of ridge-hot spot interactions in Iceland.

  14. OpenStudio - Fault Modeling

    SciTech Connect

    Frank, Stephen; Robertson, Joseph; Cheung, Howard; Horsey, Henry

    2014-09-19

    This software record documents the OpenStudio fault model development portion of the Fault Detection and Diagnostics LDRD project.The software provides a suite of OpenStudio measures (scripts) for modeling typical HVAC system faults in commercial buildings and also included supporting materials: example projects and OpenStudio measures for reporting fault costs and energy impacts.

  15. Soft Computing Application in Fault Detection of Induction Motor

    SciTech Connect

    Konar, P.; Puhan, P. S.; Chattopadhyay, P. Dr.

    2010-10-26

    The paper investigates the effectiveness of different patter classifier like Feed Forward Back Propagation (FFBPN), Radial Basis Function (RBF) and Support Vector Machine (SVM) for detection of bearing faults in Induction Motor. The steady state motor current with Park's Transformation has been used for discrimination of inner race and outer race bearing defects. The RBF neural network shows very encouraging results for multi-class classification problems and is hoped to set up a base for incipient fault detection of induction motor. SVM is also found to be a very good fault classifier which is highly competitive with RBF.

  16. Hayward Fault, California Interferogram

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This image of California's Hayward fault is an interferogram created using a pair of images taken by Synthetic Aperture Radar(SAR) combined to measure changes in the surface that may have occurred between the time the two images were taken.

    The images were collected by the European Space Agency's Remote Sensing satellites ERS-1 and ERS-2 in June 1992 and September 1997 over the central San Francisco Bay in California.

    The radar image data are shown as a gray-scale image, with the interferometric measurements that show the changes rendered in color. Only the urbanized area could be mapped with these data. The color changes from orange tones to blue tones across the Hayward fault (marked by a thin red line) show about 2-3centimeters (0.8-1.1 inches) of gradual displacement or movement of the southwest side of the fault. The block west of the fault moved horizontally toward the northwest during the 63 months between the acquisition of the two SAR images. This fault movement is called a seismic creep because the fault moved slowly without generating an earthquake.

    Scientists are using the SAR interferometry along with other data collected on the ground to monitor this fault motion in an attempt to estimate the probability of earthquake on the Hayward fault, which last had a major earthquake of magnitude 7 in 1868. This analysis indicates that the northern part of the Hayward fault is creeping all the way from the surface to a depth of 12 kilometers (7.5 miles). This suggests that the potential for a large earthquake on the northern Hayward fault might be less than previously thought. The blue area to the west (lower left) of the fault near the center of the image seemed to move upward relative to the yellow and orange areas nearby by about 2 centimeters (0.8 inches). The cause of this apparent motion is not yet confirmed, but the rise of groundwater levels during the time between the images may have caused the reversal of a small portion of the subsidence that

  17. Cable-fault locator

    NASA Technical Reports Server (NTRS)

    Cason, R. L.; Mcstay, J. J.; Heymann, A. P., Sr.

    1979-01-01

    Inexpensive system automatically indicates location of short-circuited section of power cable. Monitor does not require that cable be disconnected from its power source or that test signals be applied. Instead, ground-current sensors are installed in manholes or at other selected locations along cable run. When fault occurs, sensors transmit information about fault location to control center. Repair crew can be sent to location and cable can be returned to service with minimum of downtime.

  18. [X-ray diffraction and infrared spectrum analysis of fault gouge in Wenchuan seismic belt].

    PubMed

    Wang, Zheng-Yang; Cao, Jian-Jin; Luo, Song-Ying; Liao, Yi-Peng

    2014-05-01

    Wenchuan earthquake produced a series of co-seismic surface ruptures in Leigu and Zhaojiagou, and we collected samples of co-seismic fault gouge in the surface ruptures as well as the old gouge in the fault of Nanba. Testing The new and old fault gouge was tested with X-ray diffraction and infrared absorption spectra, and its characteristics such as mineral compositions, clay mineral contents and combinations were comprehensively analyzed. The results display obvious differences between the new and old fault gouge, showing that the old fault gouge is mainly composed of wall rock debris or milled powders, while the main components of new fault gouge are clay minerals. The assemblage of clay minerals composition shows that the environment of the fault activity was mainly warm and humid, and the clay minerals were mainly transformed by low temperature and low pressure dynamic metamorphism. And this also partly indicates that the latest way of the fault activity in this area may be a creeping. However the previous researches on the fault gouge of Wenchuan earthquake fault zone are mainly focused on its mechanical properties as well as its texture and structure, the research in this paper is to determine the physical and chemical environment of fault activity through the mineral compositions and clay mineral contents in the fault gouge characteristics, and this research has important scientific significance to the researches on the evolution of the fault environment and the activity mechanism of the earthquake. PMID:25095450

  19. [X-ray diffraction and infrared spectrum analysis of fault gouge in Wenchuan seismic belt].

    PubMed

    Wang, Zheng-Yang; Cao, Jian-Jin; Luo, Song-Ying; Liao, Yi-Peng

    2014-05-01

    Wenchuan earthquake produced a series of co-seismic surface ruptures in Leigu and Zhaojiagou, and we collected samples of co-seismic fault gouge in the surface ruptures as well as the old gouge in the fault of Nanba. Testing The new and old fault gouge was tested with X-ray diffraction and infrared absorption spectra, and its characteristics such as mineral compositions, clay mineral contents and combinations were comprehensively analyzed. The results display obvious differences between the new and old fault gouge, showing that the old fault gouge is mainly composed of wall rock debris or milled powders, while the main components of new fault gouge are clay minerals. The assemblage of clay minerals composition shows that the environment of the fault activity was mainly warm and humid, and the clay minerals were mainly transformed by low temperature and low pressure dynamic metamorphism. And this also partly indicates that the latest way of the fault activity in this area may be a creeping. However the previous researches on the fault gouge of Wenchuan earthquake fault zone are mainly focused on its mechanical properties as well as its texture and structure, the research in this paper is to determine the physical and chemical environment of fault activity through the mineral compositions and clay mineral contents in the fault gouge characteristics, and this research has important scientific significance to the researches on the evolution of the fault environment and the activity mechanism of the earthquake.

  20. Pen Branch Fault Program

    SciTech Connect

    Price, V.; Stieve, A.L.; Aadland, R.

    1990-09-28

    Evidence from subsurface mapping and seismic reflection surveys at Savannah River Site (SRS) suggests the presence of a fault which displaces Cretaceous through Tertiary (90--35 million years ago) sediments. This feature has been described and named the Pen Branch fault (PBF) in a recent Savannah River Laboratory (SRL) paper (DP-MS-88-219). Because the fault is located near operating nuclear facilities, public perception and federal regulations require a thorough investigation of the fault to determine whether any seismic hazard exists. A phased program with various elements has been established to investigate the PBF to address the Nuclear Regulatory Commission regulatory guidelines represented in 10 CFR 100 Appendix A. The objective of the PBF program is to fully characterize the nature of the PBF (ESS-SRL-89-395). This report briefly presents current understanding of the Pen Branch fault based on shallow drilling activities completed the fall of 1989 (PBF well series) and subsequent core analyses (SRL-ESS-90-145). The results are preliminary and ongoing: however, investigations indicate that the fault is not capable. In conjunction with the shallow drilling, other activities are planned or in progress. 7 refs., 8 figs., 1 tab.

  1. Nearly frictionless faulting by unclamping in long-term interaction models

    USGS Publications Warehouse

    Parsons, T.

    2002-01-01

    In defiance of direct rock-friction observations, some transform faults appear to slide with little resistance. In this paper finite element models are used to show how strain energy is minimized by interacting faults that can cause long-term reduction in fault-normal stresses (unclamping). A model fault contained within a sheared elastic medium concentrates stress at its end points with increasing slip. If accommodating structures free up the ends, then the fault responds by rotating, lengthening, and unclamping. This concept is illustrated by a comparison between simple strike-slip faulting and a mid-ocean-ridge model with the same total transform length; calculations show that the more complex system unclapms the transforms and operates at lower energy. In another example, the overlapping San Andreas fault system in the San Francisco Bay region is modeled; this system is complicated by junctions and stepovers. A finite element model indicates that the normal stress along parts of the faults could be reduced to hydrostatic levels after ???60-100 k.y. of system-wide slip. If this process occurs in the earth, then parts of major transform fault zones could appear nearly frictionless.

  2. Packaged Fault Model for Geometric Segmentation of Active Faults Into Earthquake Source Faults

    NASA Astrophysics Data System (ADS)

    Nakata, T.; Kumamoto, T.

    2004-12-01

    In Japan, the empirical formula proposed by Matsuda (1975) mainly based on the length of the historical surface fault ruptures and magnitude, is generally applied to estimate the size of future earthquakes from the extent of existing active faults for seismic hazard assessment. Therefore validity of the active fault length and defining individual segment boundaries where propagating ruptures terminate are essential and crucial to the reliability for the accurate assessments. It is, however, not likely for us to clearly identify the behavioral earthquake segments from observation of surface faulting during the historical period, because most of the active faults have longer recurrence intervals than 1000 years in Japan. Besides uncertainties of the datasets obtained mainly from fault trenching studies are quite large for fault grouping/segmentation. This is why new methods or criteria should be applied for active fault grouping/segmentation, and one of the candidates may be geometric criterion of active faults. Matsuda (1990) used _gfive kilometer_h as a critical distance for grouping and separation of neighboring active faults. On the other hand, Nakata and Goto (1998) proposed the geometric criteria such as (1) branching features of active fault traces and (2) characteristic pattern of vertical-slip distribution along the fault traces as tools to predict rupture length of future earthquakes. The branching during the fault rupture propagation is regarded as an effective energy dissipation process and could result in final rupture termination. With respect to the characteristic pattern of vertical-slip distribution, especially with strike-slip components, the up-thrown sides along the faults are, in general, located on the fault blocks in the direction of relative strike-slip. Applying these new geometric criteria to the high-resolution active fault distribution maps, the fault grouping/segmentation could be more practically conducted. We tested this model

  3. Upper crustal fault zones: Constraining structure and dynamics using electrical conductivity

    NASA Astrophysics Data System (ADS)

    Hoffmann-Rothe, A.; Ritter, O.; Janssen, C.

    2003-04-01

    Upper crustal fault zones, either fossil or active, are often connected with electrical conductivity anomalies. These anomalies depend on properties such as the porosity/permeability of the fault zone material, the fluid content or the state of healing/cementation of the fault-fracture mesh; properties that moreover control the ability of a fault to accumulate strain. Structural heterogeneities caused by the faulting process are therefore believed to either increase or decrease the electrical conductivity in the fault's vicinity. We show results of two combined magnetotelluric and structural studies of large scale strike-slip dominated fault zones. The trench-linked West Fault (WF) in Northern Chile shows a pronounced anomaly of high conductivity confined to the central region of the fault. The zone of high conductivity is approximately 400 m wide and 1.5 km deep. Structural mapping reveals that this conductivity enhancement is closely related to a mesh of faults and fractures ('damage zone') that most likely provides a pathway for fluids. In contrast to this, the Dead Sea Transform Fault (DST) in Jordan shows no obvious evidence of such a fault zone conductor as the DST is expressed as the boundary between two different domains of conductivity on either side of the fault. Correspondingly, a marked macroscopic fault-fracture mesh in the fault core region is not developed. Comparison of the results from the WF with published data from the San Andreas Fault suggests generally a positive correlation of fault activity with geometric extent and conductivity of the fault zone conductor. However, the Dead Sea Transform Fault apparently does not comply with this scheme although it is active. It is possible that intense localisation of deformation caused the formation of a very narrow fault gouge, which cannot be resolved with the MT experiments. This result could suggest that the existence or non-existence of high conductivity in the central parts of large scale strike

  4. Structure of a continental strike-slip fault from deep seismic reflection: Walls Boundary fault, northern British Caledonides

    NASA Astrophysics Data System (ADS)

    McBride, John H.

    1994-12-01

    Reprocessing of four offshore deep reflection profiles across the Walls Boundary strike-slip fault, postulated as the northward continuation of the Great Glen fault over the Shetland platform, provides useful constraints on the lithospheric structure of a major continental transform and some insight into the manner in which strike-slip faults deform. The reprocessing was aimed at delineating complex structure and reducing noise contamination and consisted of analyses of diffractions and amplitude variations and experimentation with seismic migration. The results demonstrate a highly variable crustal and uppermost mantle structure for the Walls Boundary fault along more than 150 km of its length. Six key observations can be made from this study. A vertical or steeply dipping structure is deduced for the fault in much of the crust and perhaps parts of the uppermost mantle; however, more diverse reflecting structures and interpreted for the lower crust, such as the Moho deflection and steeply dipping reflectors directly beneath the fault that may have been related to a localized component of transpression and resultant crustal thickening. The presence of diffractions at the level of the Moho discontinuity where the downward projection of the fault intersects it suggests points of structural 'roughness' that may be related to deformation of the Moho by late motion along the fault. Integrating the interpretation of the reflection data with previous geological studies implies that the age of the Moho deflection is post Early Cretaceous but that the dipping structure adjacent to and cut off by the fault is probably Caledonian (Silurian-Early Devonian). Although the disparate structure of the crust on opposite sides of the fault supports geologic interpretations of large-scale displacement, a major step in the Moho discontinuity directly beneath the Walls Boundary fault cannot be substantiated from the seismic data.

  5. Kinematic study at the junction of the East Anatolian fault and the Dead Sea fault from GPS measurements

    NASA Astrophysics Data System (ADS)

    Mahmoud, Yasser; Masson, Frederic; Meghraoui, Mustapha; Cakir, Ziyadin; Alchalbi, Abdulmutaleb; Yavasoglu, Hakan; Yönlü, Onder; Daoud, Mohamed; Ergintav, Semih; Inan, Sedat

    2013-07-01

    The Hatay Triple Junction (HTJ) is a tectonically complex area located at the intersection between the left-lateral East Anatolian fault (EAF), the Cyprus subduction arc and the left-lateral Dead Sea fault (DSF) which is a transform boundary between the Arabian and Sinai plates as they converge toward Eurasia. Previous GPS studies indicate a left-lateral strike-slip rate across the DSF varying from 5 mm/yr (along the southern part) to 2 mm/yr (along the northern part) (Alchalbi et al., 2010; Gomez et al., 2007; Le Béon et al., 2008; Mahmoud et al., 2005; Al-Tarazi et al., 2011). In contrast, the EAF has a roughly constant velocity along strike estimated at 9.7 + 0.9 mm/yr (Reilinger et al., 2006). The HTJ contains several well-identified active fault segments (DSF, EAF, Osmaniye fault, Karasu fault, Latakia fault, Jisr-al-shuggur fault, Idleb fault and Afrin fault) (Meghraoui et al., 2011), the fault-slip rates for which are poorly constrained. In order to constrain better the slip rate on faults, we established a network of 57 GPS sites in NW Syria and in SE Turkey. The first campaign was carried out in September 2009; a second took place in September and November 2010 and a third (only in Turkey) in September 2011. Although the velocity field vectors computed from the 2009, 2010 and 2011 measurements appear consistent with other local studies, the results are hampered by large uncertainties due to the short observation period. However, preliminary interpretations are consistent with decreasing velocity along the DSF from south to north reported previously.

  6. Changes in fault length distributions due to fault linkage

    NASA Astrophysics Data System (ADS)

    Xu, Shunshan; Nieto-Samaniego, A. F.; Alaniz-Álvarez, S. A.; Velasquillo-Martínez, L. G.; Grajales-Nishimura, J. M.; García-Hernández, J.; Murillo-Muñetón, G.

    2010-01-01

    Fault linkage plays an important role in the growth of faults. In this paper we analyze a published synthetic model to simulate fault linkage. The results of the simulation indicate that fault linkage is the cause of the shallower local slopes on the length-frequency plots. The shallower local slopes lead to two effects. First, the curves of log cumulative number against log length exhibit fluctuating shapes as reported in literature. Second, for a given fault population, the power-law exponents after linkage are negatively related to the linked length scales. Also, we present datasets of fault length measured from four structural maps at the Cantarell oilfield in the southern Gulf of Mexico (offshore Campeche). The results demonstrate that the fault length data, corrected by seismic resolution at the tip fault zone, also exhibit fluctuating curves of log cumulative frequency vs. log length. The steps (shallower slopes) on the curves imply the scale positions of fault linkage. We conclude that fault linkage is the main reason for the fluctuating shapes of log cumulative frequency vs. log length. On the other hand, our data show that the two-tip faults are better for linear analysis between maximum displacement ( D) and length ( L). Evidently, two-tip faults underwent fewer fault linkages and interactions.

  7. Principal fault zone width and permeability of the active Neodani fault, Nobi fault system, Southwest Japan

    NASA Astrophysics Data System (ADS)

    Tsutsumi, A.; Nishino, S.; Mizoguchi, K.; Hirose, T.; Uehara, S.; Sato, K.; Tanikawa, W.; Shimamoto, T.

    2004-02-01

    The internal structure and permeability of the Neodani fault, which was last activated at the time of the 1891 Nobi earthquake (M8.0), were examined through field survey and experiments. A new exposure of the fault at a road construction site reveals a highly localized feature of the past fault deformation within a narrow fault core zone. The fault of the area consists of three zone units towards the fault core: (a) protolith rocks; (b) 15 to 30 m of fault breccia, and (c) 200 mm green to black fault gouge. Within the fault breccia zone, cataclastic foliation oblique to the fault has developed in a fine-grained 2-m-wide zone adjacent to the fault. Foliation is defined by subparallel alignment of intact lozenge shaped clasts, or by elongated aggregates of fine-grained chert fragments. The mean angle of 20°, between the foliation and the fault plane suggests that the foliated breccia accommodated a shear strain of γ<5 assuming simple shear for the rotation of the cataclastic foliation. Previous trench surveys have revealed that the fault has undergone at least 70 m of fault displacement within the last 20,000 years in this locality. The observed fault geometry suggests that past fault displacements have been localized into the 200-mm-wide gouge zone. Gas permeability analysis of the gouges gives low values of the order of 10 -20 m 2. Water permeability as low as 10 -20 m 2 is therefore expected for the fault gouge zone, which is two orders of magnitude lower than the critical permeability suggested for a fault to cause thermal pressurization during a fault slip.

  8. Mechanical and lithological controls on the development of heterogeneous fault zones: an example from the southern Dead Sea Fault System, Israel

    NASA Astrophysics Data System (ADS)

    Evans, Siân; Holdsworth, Bob; Imber, Jonny; de Paola, Nicola; Marco, Shmuel; Weinberger, Rami

    2014-05-01

    The mechanical weakening processes involved in the development of major crustal fault systems have been widely documented, and it is recognised that clay-bearing fault rocks frequently have a significant influence on fault strength and slip behaviour in the upper crust. It is less well-understood how mechanical processes, such as cataclasis and the mechanical entrainment of fault rock materials along fault zones (e.g. "smearing"), interact with chemical processes, such as clay mineral transformations and phyllonitisation during fault rock development. These processes can combine to form fault zones that may be both lithologically and mechanically heterogeneous, and which may also evolve over time, changing the nature of observed heterogeneities. We present here data from exhumed sections of the southern Dead Sea Fault System, Israel, an active continental transform fault that has accumulated 105 km of sinistral displacement since the mid-Miocene. These faults are estimated to have been active at shallow depths (<5 km, but potentially significantly less. The so-called "fault cores" of these sections are highly heterogeneous and are comprised of material formed by a variety of processes: fault gouges formed by cataclasis; coarser-grained, variably crushed crystalline basement rocks; mechanically entrained highly mobile units, derived from shale in adjacent cover sequence wall rocks; and growth of authegenic mineral phases through alteration and pressure solution. Through operation of grain-size reduction and diffusive mass transfer processes, we see a bulk change from fault rocks dominated by relatively strong phases displaying no obvious fabric, such as feldspars and calcite, through to foliated phyllosilicate-rich (illite, chlorite, smectite) fault rocks which likely have much lower frictional strengths. Mechanically entrained shale that has not undergone significant brittle deformation can also efficiently introduce large volumes of relatively weak material into

  9. Wetland losses related to fault movement and hydrocarbon production, southeastern Texas coast

    USGS Publications Warehouse

    White, William A.; Morton, Robert A.

    1997-01-01

    Time series analyses of surface fault activity and nearby hydrocarbon production from the southeastern Texas coast show a high correlation among volume of produced fluids, timing of fault activation, rates of subsidence, and rates of wetland loss. Greater subsidence on the downthrown sides of faults contributes to more frequent flooding and generally wetter conditions, which are commonly reflected by changes in plant communities {e.g., Spartina patens to Spartina alterniflora) or progressive transformation of emergent vegetation to open water. Since the 1930s and 1950s, approximately 5,000 hectares of marsh habitat has been lost as a result of subsidence associated with faulting. Marsh- es have expanded locally along faults where hydrophytic vegetation has spread into former upland areas. Fault traces are linear to curvilinear and are visible because elevation differences across faults alter soil hydrology and vegetation. Fault lengths range from 1 to 13.4 km and average 3.8 km. Seventy-five percent of the faults visible on recent aerial photographs are not visible on photographs taken in the 1930's, indicating relatively recent fault movement. At least 80% of the surface faults correlate with extrapolated subsurface faults; the correlation increases to more than 90% when certain assumptions are made to compensate for mismatches in direction of displacement. Coastal wetlands loss in Texas associated with hydrocarbon extraction will likely increase where production in mature fields is prolonged without fiuid reinjection.

  10. Fault terminations, Seminoe Mountains, Wyoming

    SciTech Connect

    Dominic, J.B.; McConnell, D.A. . Dept. of Geology)

    1992-01-01

    Two basement-involved faults terminate in folds in the Seminoe Mountains. Mesoscopic and macroscopic structures in sedimentary rocks provide clues to the interrelationship of faults and folds in this region, and on the linkage between faulting and folding in general. The Hurt Creek fault trends 320[degree] and has maximum separation of 1.5 km measured at the basement/cover contact. Separation on the fault decreases upsection to zero within the Jurassic Sundance Formation. Unfaulted rock units form an anticline around the fault tip. The complementary syncline is angular with planar limbs and a narrow hinge zone. The syncline axial trace intersects the fault in the footwall at the basement/cover cut-off. Map patterns are interpreted to show thickening of Mesozoic units adjacent to the syncline hinge. In contrast, extensional structures are common in the faulted anticline within the Permian Goose Egg and Triassic Chugwater Formations. A hanging wall splay fault loses separation into the Goose Egg formation which is thinned by 50% at the fault tip. Mesoscopic normal faults are oriented 320--340[degree] and have an average inclination of 75[degree] SW. Megaboudins of Chugwater are present in the footwall of the Hurt Creek fault, immediately adjacent to the fault trace. The Black Canyon fault transported Precambrian-Pennsylvanian rocks over Pennsylvanian Tensleep sandstone. This fault is layer-parallel at the top of the Tensleep and loses separation along strike into an unfaulted syncline in the Goose Egg Formation. Shortening in the pre-Permian units is accommodated by slip on the basement-involved Black Canyon fault. Equivalent shortening in Permian-Cretaceous units occurs on a system of thin-skinned'' thrust faults.

  11. Fault displacement hazard for strike-slip faults

    USGS Publications Warehouse

    Petersen, M.D.; Dawson, T.E.; Chen, R.; Cao, T.; Wills, C.J.; Schwartz, D.P.; Frankel, A.D.

    2011-01-01

    In this paper we present a methodology, data, and regression equations for calculating the fault rupture hazard at sites near steeply dipping, strike-slip faults. We collected and digitized on-fault and off-fault displacement data for 9 global strikeslip earthquakes ranging from moment magnitude M 6.5 to M 7.6 and supplemented these with displacements from 13 global earthquakes compiled byWesnousky (2008), who considers events up to M 7.9. Displacements on the primary fault fall off at the rupture ends and are often measured in meters, while displacements on secondary (offfault) or distributed faults may measure a few centimeters up to more than a meter and decay with distance from the rupture. Probability of earthquake rupture is less than 15% for cells 200 m??200 m and is less than 2% for 25 m??25 m cells at distances greater than 200mfrom the primary-fault rupture. Therefore, the hazard for off-fault ruptures is much lower than the hazard near the fault. Our data indicate that rupture displacements up to 35cm can be triggered on adjacent faults at distances out to 10kmor more from the primary-fault rupture. An example calculation shows that, for an active fault which has repeated large earthquakes every few hundred years, fault rupture hazard analysis should be an important consideration in the design of structures or lifelines that are located near the principal fault, within about 150 m of well-mapped active faults with a simple trace and within 300 m of faults with poorly defined or complex traces.

  12. Computer hardware fault administration

    DOEpatents

    Archer, Charles J.; Megerian, Mark G.; Ratterman, Joseph D.; Smith, Brian E.

    2010-09-14

    Computer hardware fault administration carried out in a parallel computer, where the parallel computer includes a plurality of compute nodes. The compute nodes are coupled for data communications by at least two independent data communications networks, where each data communications network includes data communications links connected to the compute nodes. Typical embodiments carry out hardware fault administration by identifying a location of a defective link in the first data communications network of the parallel computer and routing communications data around the defective link through the second data communications network of the parallel computer.

  13. Fault tolerant linear actuator

    DOEpatents

    Tesar, Delbert

    2004-09-14

    In varying embodiments, the fault tolerant linear actuator of the present invention is a new and improved linear actuator with fault tolerance and positional control that may incorporate velocity summing, force summing, or a combination of the two. In one embodiment, the invention offers a velocity summing arrangement with a differential gear between two prime movers driving a cage, which then drives a linear spindle screw transmission. Other embodiments feature two prime movers driving separate linear spindle screw transmissions, one internal and one external, in a totally concentric and compact integrated module.

  14. Maximum earthquake magnitudes along different sections of the North Anatolian fault zone

    NASA Astrophysics Data System (ADS)

    Bohnhoff, Marco; Martínez-Garzón, Patricia; Bulut, Fatih; Stierle, Eva; Ben-Zion, Yehuda

    2016-04-01

    Constraining the maximum likely magnitude of future earthquakes on continental transform faults has fundamental consequences for the expected seismic hazard. Since the recurrence time for those earthquakes is typically longer than a century, such estimates rely primarily on well-documented historical earthquake catalogs, when available. Here we discuss the maximum observed earthquake magnitudes along different sections of the North Anatolian Fault Zone (NAFZ) in relation to the age of the fault activity, cumulative offset, slip rate and maximum length of coherent fault segments. The findings are based on a newly compiled catalog of historical earthquakes in the region, using the extensive literary sources that exist owing to the long civilization record. We find that the largest M7.8-8.0 earthquakes are exclusively observed along the older eastern part of the NAFZ that also has longer coherent fault segments. In contrast, the maximum observed events on the younger western part where the fault branches into two or more strands are smaller. No first-order relations between maximum magnitudes and fault offset or slip rates are found. The results suggest that the maximum expected earthquake magnitude in the densely populated Marmara-Istanbul region would probably not exceed M7.5. The findings are consistent with available knowledge for the San Andreas Fault and Dead Sea Transform, and can help in estimating hazard potential associated with different sections of large transform faults.

  15. Fault tree models for fault tolerant hypercube multiprocessors

    NASA Technical Reports Server (NTRS)

    Boyd, Mark A.; Tuazon, Jezus O.

    1991-01-01

    Three candidate fault tolerant hypercube architectures are modeled, their reliability analyses are compared, and the resulting implications of these methods of incorporating fault tolerance into hypercube multiprocessors are discussed. In the course of performing the reliability analyses, the use of HARP and fault trees in modeling sequence dependent system behaviors is demonstrated.

  16. Using the EMD method to determine fault criterion for medium-low pressure gas regulators

    NASA Astrophysics Data System (ADS)

    Hao, Xuejun; Liu, Qiang; Yang, Guobin; Du, Yi

    2015-11-01

    By extracting the outlet pressure data of gas regulators, this paper uses the EMD toolbox of the MATLAB software, which can perform data decomposition and the Hilbert-Huang Transform to find the rules with fault data. Eventually, the medium-low pressure gas regulator fault criterion can be established.

  17. Characteristics of On-fault and Off-fault displacement of various fault types based on numerical simulation

    NASA Astrophysics Data System (ADS)

    Inoue, N.; Kitada, N.; Takemura, K.

    2015-12-01

    There are two types of fault displacement related to the earthquake fault: on-fault displacement and off-fault displacement. Off-fault displacement should be evaluated in important facilities, such as Nuclear Installations. Probabilistic Fault Displacement Hazard Analysis (PFDHA) is developing on the basis of PSHA. PFDHA estimates on-fault and off-fault displacement. For estimation, PFDHA uses distance-displacement functions, which are constructed from field measurement data. However, observed displacement data are still sparse, especially off-fault displacement. In Nuclear Installations, estimation of off-fault displacement is more important than that of on-fault. We carried out numerical fault displacement simulations to assist in understanding distance-displacement relations of on-fault and off-fault according to fault types, normal, reverse and strike fault. We used Okada's dislocation method. The displacements were calculated based on the single fault model with several rakes of slip. On-fault displacements (along the fault profile) of each fault types show a similar trend. Off-fault displacements (cross profile to the fault) of vertical (reverse and normal) fault types show the rapid decreasing displacement on the foot wall side. In the presentation, we will show the displacement profile and also stress, strain and so on. The dislocation model can not express discontinuous displacements. In the future, we will apply various numerical simulations (Finite Element Method, Distinct Element Method) in order to evaluate off-fault displacements. We will also compare numerical simulation results with observed data.

  18. Robust fault detection of turbofan engines subject to adaptive controllers via a Total Measurable Fault Information Residual (ToMFIR) technique.

    PubMed

    Chen, Wen; Chowdhury, Fahmida N; Djuric, Ana; Yeh, Chih-Ping

    2014-09-01

    This paper provides a new design of robust fault detection for turbofan engines with adaptive controllers. The critical issue is that the adaptive controllers can depress the faulty effects such that the actual system outputs remain the pre-specified values, making it difficult to detect faults/failures. To solve this problem, a Total Measurable Fault Information Residual (ToMFIR) technique with the aid of system transformation is adopted to detect faults in turbofan engines with adaptive controllers. This design is a ToMFIR-redundancy-based robust fault detection. The ToMFIR is first introduced and existing results are also summarized. The Detailed design process of the ToMFIRs is presented and a turbofan engine model is simulated to verify the effectiveness of the proposed ToMFIR-based fault-detection strategy.

  19. The property of fault zone and fault activity of Shionohira Fault, Fukushima, Japan

    NASA Astrophysics Data System (ADS)

    Seshimo, K.; Aoki, K.; Tanaka, Y.; Niwa, M.; Kametaka, M.; Sakai, T.; Tanaka, Y.

    2015-12-01

    The April 11, 2011 Fukushima-ken Hamadori Earthquake (hereafter the 4.11 earthquake) formed co-seismic surface ruptures trending in the NNW-SSE direction in Iwaki City, Fukushima Prefecture, which were newly named as the Shionohira Fault by Ishiyama et al. (2011). This earthquake was characterized by a westward dipping normal slip faulting, with a maximum displacement of about 2 m (e.g., Kurosawa et al., 2012). To the south of the area, the same trending lineaments were recognized to exist even though no surface ruptures occurred by the earthquake. In an attempt to elucidate the differences of active and non-active segments of the fault, this report discusses the results of observation of fault outcrops along the Shionohira Fault as well as the Coulomb stress calculations. Only a few outcrops have basement rocks of both the hanging-wall and foot-wall of the fault plane. Three of these outcrops (Kyodo-gawa, Shionohira and Betto) were selected for investigation. In addition, a fault outcrop (Nameishi-minami) located about 300 m south of the southern tip of the surface ruptures was investigated. The authors carried out observations of outcrops, polished slabs and thin sections, and performed X-ray diffraction (XRD) to fault materials. As a result, the fault zones originating from schists were investigated at Kyodo-gawa and Betto. A thick fault gouge was cut by a fault plane of the 4.11 earthquake in each outcrop. The fault materials originating from schists were fault bounded with (possibly Neogene) weakly deformed sandstone at Shionohira. A thin fault gouge was found along the fault plane of 4.11 earthquake. A small-scale fault zone with thin fault gouge was observed in Nameishi-minami. According to XRD analysis, smectite was detected in the gouges from Kyodo-gawa, Shionohira and Betto, while not in the gouge from Nameishi-minami.

  20. Fault-Tolerant Flight Computer

    NASA Technical Reports Server (NTRS)

    Chau, Savio

    1996-01-01

    In design concept for adaptive, fault-tolerant flight computer, upon detection of fault in either processor, surviving processor assumes responsibility for both equipment systems. Possible because of cross-strapping between processors, memories, and input/output units. Concept also applicable to other computing systems required to tolerate faults and in which partial loss of processing speed or functionality acceptable price to pay for continued operation in event of faults.

  1. Towards Fault Resilient Global Arrays

    SciTech Connect

    Tipparaju, Vinod; Krishnan, Manoj Kumar; Palmer, Bruce J.; Petrini, Fabrizio; Nieplocha, Jaroslaw

    2007-09-03

    The focus of the current paper is adding fault resiliency to the Global Arrays. We extended the GA toolkit to provide a minimal level of capabilities to enable programmer to implement fault resiliency at the user level. Our fault-recovery approach is programmer assisted and based on frequent incremental checkpoints and rollback recovery. In addition, it relies of pool of spare nodes that are used to replace the failing node. We demonstrate usefulness of fault resilient Global Arrays in application context.

  2. Analysis of surface structures of major strike-slip faults

    NASA Astrophysics Data System (ADS)

    Hsieh, Shang Yu; Neubauer, Franz

    2013-04-01

    much larger by numerous cumulative earthquakes. Surface ruptures has certain length and width of 5 m to ~200 m, 3 to ~350 m in the Kunlun fault (Lin and Nishikawa, 2011) and 10 to ~450 m, 30 to ~300 m in Greendale fault (Quigley et al., 2012). Beside the scale difference, the statistical approach also applied in the parameters of these surface features, result shows in these four faults, there are specific correlations exist among lengths, width, height and convergence angle which is also the key point to explore the depth of these structures with analog experiments. A likely explanation for the differences between Altyn/San Andreas faults and Kunlun/Glendale fault is the transpressive nature of Altyn/San Andreas faults and the pure strike-slip/transform nature of Glendale/Kunlun faults implying a small convergence angle in the latter case.

  3. Tacting "To a Fault."

    ERIC Educational Resources Information Center

    Baer, Donald M.

    1991-01-01

    This paper argues that behavior analysis is not technological to a fault, but rather has a faulty technology by being incomplete. The paper examines reinforcers and punishers that result from the outcomes of either (1) striving for better experimental control, or (2) inventing theories to explain why current control is imperfect. (JDD)

  4. Row fault detection system

    SciTech Connect

    Archer, Charles Jens; Pinnow, Kurt Walter; Ratterman, Joseph D.; Smith, Brian Edward

    2008-10-14

    An apparatus, program product and method checks for nodal faults in a row of nodes by causing each node in the row to concurrently communicate with its adjacent neighbor nodes in the row. The communications are analyzed to determine a presence of a faulty node or connection.

  5. Fault-Mechanism Simulator

    ERIC Educational Resources Information Center

    Guyton, J. W.

    1972-01-01

    An inexpensive, simple mechanical model of a fault can be produced to simulate the effects leading to an earthquake. This model has been used successfully with students from elementary to college levels and can be demonstrated to classes as large as thirty students. (DF)

  6. Row fault detection system

    DOEpatents

    Archer, Charles Jens; Pinnow, Kurt Walter; Ratterman, Joseph D.; Smith, Brian Edward

    2010-02-23

    An apparatus and program product check for nodal faults in a row of nodes by causing each node in the row to concurrently communicate with its adjacent neighbor nodes in the row. The communications are analyzed to determine a presence of a faulty node or connection.

  7. Row fault detection system

    DOEpatents

    Archer, Charles Jens; Pinnow, Kurt Walter; Ratterman, Joseph D.; Smith, Brian Edward

    2012-02-07

    An apparatus, program product and method check for nodal faults in a row of nodes by causing each node in the row to concurrently communicate with its adjacent neighbor nodes in the row. The communications are analyzed to determine a presence of a faulty node or connection.

  8. Fault-Related Sanctuaries

    NASA Astrophysics Data System (ADS)

    Piccardi, L.

    2001-12-01

    Beyond the study of historical surface faulting events, this work investigates the possibility, in specific cases, of identifying pre-historical events whose memory survives in myths and legends. The myths of many famous sacred places of the ancient world contain relevant telluric references: "sacred" earthquakes, openings to the Underworld and/or chthonic dragons. Given the strong correspondence with local geological evidence, these myths may be considered as describing natural phenomena. It has been possible in this way to shed light on the geologic origin of famous myths (Piccardi, 1999, 2000 and 2001). Interdisciplinary researches reveal that the origin of several ancient sanctuaries may be linked in particular to peculiar geological phenomena observed on local active faults (like ground shaking and coseismic surface ruptures, gas and flames emissions, strong underground rumours). In many of these sanctuaries the sacred area is laid directly above the active fault. In a few cases, faulting has affected also the archaeological relics, right through the main temple (e.g. Delphi, Cnidus, Hierapolis of Phrygia). As such, the arrangement of the cult site and content of relative myths suggest that specific points along the trace of active faults have been noticed in the past and worshiped as special `sacred' places, most likely interpreted as Hades' Doors. The mythological stratification of most of these sanctuaries dates back to prehistory, and points to a common derivation from the cult of the Mother Goddess (the Lady of the Doors), which was largely widespread since at least 25000 BC. The cult itself was later reconverted into various different divinities, while the `sacred doors' of the Great Goddess and/or the dragons (offspring of Mother Earth and generally regarded as Keepers of the Doors) persisted in more recent mythologies. Piccardi L., 1999: The "Footprints" of the Archangel: Evidence of Early-Medieval Surface Faulting at Monte Sant'Angelo (Gargano, Italy

  9. Quantifying Anderson's fault types

    USGS Publications Warehouse

    Simpson, R.W.

    1997-01-01

    Anderson [1905] explained three basic types of faulting (normal, strike-slip, and reverse) in terms of the shape of the causative stress tensor and its orientation relative to the Earth's surface. Quantitative parameters can be defined which contain information about both shape and orientation [Ce??le??rier, 1995], thereby offering a way to distinguish fault-type domains on plots of regional stress fields and to quantify, for example, the degree of normal-faulting tendencies within strike-slip domains. This paper offers a geometrically motivated generalization of Angelier's [1979, 1984, 1990] shape parameters ?? and ?? to new quantities named A?? and A??. In their simple forms, A?? varies from 0 to 1 for normal, 1 to 2 for strike-slip, and 2 to 3 for reverse faulting, and A?? ranges from 0?? to 60??, 60?? to 120??, and 120?? to 180??, respectively. After scaling, A?? and A?? agree to within 2% (or 1??), a difference of little practical significance, although A?? has smoother analytical properties. A formulation distinguishing horizontal axes as well as the vertical axis is also possible, yielding an A?? ranging from -3 to +3 and A?? from -180?? to +180??. The geometrically motivated derivation in three-dimensional stress space presented here may aid intuition and offers a natural link with traditional ways of plotting yield and failure criteria. Examples are given, based on models of Bird [1996] and Bird and Kong [1994], of the use of Anderson fault parameters A?? and A?? for visualizing tectonic regimes defined by regional stress fields. Copyright 1997 by the American Geophysical Union.

  10. Earthquakes and fault creep on the northern San Andreas fault

    USGS Publications Warehouse

    Nason, R.

    1979-01-01

    At present there is an absence of both fault creep and small earthquakes on the northern San Andreas fault, which had a magnitude 8 earthquake with 5 m of slip in 1906. The fault has apparently been dormant after the 1906 earthquake. One possibility is that the fault is 'locked' in some way and only produces great earthquakes. An alternative possibility, presented here, is that the lack of current activity on the northern San Andreas fault is because of a lack of sufficient elastic strain after the 1906 earthquake. This is indicated by geodetic measurements at Fort Ross in 1874, 1906 (post-earthquake), and 1969, which show that the strain accumulation in 1969 (69 ?? 10-6 engineering strain) was only about one-third of the strain release (rebound) in the 1906 earthquake (200 ?? 10-6 engineering strain). The large difference in seismicity before and after 1906, with many strong local earthquakes from 1836 to 1906, but only a few strong earthquakes from 1906 to 1976, also indicates a difference of elastic strain. The geologic characteristics (serpentine, fault straightness) of most of the northern San Andreas fault are very similar to the characteristics of the fault south of Hollister, where fault creep is occurring. Thus, the current absence of fault creep on the northern fault segment is probably due to a lack of sufficient elastic strain at the present time. ?? 1979.

  11. Interactive Retro-Deformation of Terrain for Reconstructing 3D Fault Displacements.

    PubMed

    Westerteiger, R; Compton, T; Bernadin, T; Cowgill, E; Gwinner, K; Hamann, B; Gerndt, A; Hagen, H

    2012-12-01

    Planetary topography is the result of complex interactions between geological processes, of which faulting is a prominent component. Surface-rupturing earthquakes cut and move landforms which develop across active faults, producing characteristic surface displacements across the fault. Geometric models of faults and their associated surface displacements are commonly applied to reconstruct these offsets to enable interpretation of the observed topography. However, current 2D techniques are limited in their capability to convey both the three-dimensional kinematics of faulting and the incremental sequence of events required by a given reconstruction. Here we present a real-time system for interactive retro-deformation of faulted topography to enable reconstruction of fault displacement within a high-resolution (sub 1m/pixel) 3D terrain visualization. We employ geometry shaders on the GPU to intersect the surface mesh with fault-segments interactively specified by the user and transform the resulting surface blocks in realtime according to a kinematic model of fault motion. Our method facilitates a human-in-the-loop approach to reconstruction of fault displacements by providing instant visual feedback while exploring the parameter space. Thus, scientists can evaluate the validity of traditional point-to-point reconstructions by visually examining a smooth interpolation of the displacement in 3D. We show the efficacy of our approach by using it to reconstruct segments of the San Andreas fault, California as well as a graben structure in the Noctis Labyrinthus region on Mars.

  12. Interactive Retro-Deformation of Terrain for Reconstructing 3D Fault Displacements.

    PubMed

    Westerteiger, R; Compton, T; Bernadin, T; Cowgill, E; Gwinner, K; Hamann, B; Gerndt, A; Hagen, H

    2012-12-01

    Planetary topography is the result of complex interactions between geological processes, of which faulting is a prominent component. Surface-rupturing earthquakes cut and move landforms which develop across active faults, producing characteristic surface displacements across the fault. Geometric models of faults and their associated surface displacements are commonly applied to reconstruct these offsets to enable interpretation of the observed topography. However, current 2D techniques are limited in their capability to convey both the three-dimensional kinematics of faulting and the incremental sequence of events required by a given reconstruction. Here we present a real-time system for interactive retro-deformation of faulted topography to enable reconstruction of fault displacement within a high-resolution (sub 1m/pixel) 3D terrain visualization. We employ geometry shaders on the GPU to intersect the surface mesh with fault-segments interactively specified by the user and transform the resulting surface blocks in realtime according to a kinematic model of fault motion. Our method facilitates a human-in-the-loop approach to reconstruction of fault displacements by providing instant visual feedback while exploring the parameter space. Thus, scientists can evaluate the validity of traditional point-to-point reconstructions by visually examining a smooth interpolation of the displacement in 3D. We show the efficacy of our approach by using it to reconstruct segments of the San Andreas fault, California as well as a graben structure in the Noctis Labyrinthus region on Mars. PMID:26357128

  13. Chloroplast transformation.

    PubMed

    Lu, Xiao-Mei; Yin, Wei-Bo; Hu, Zan-Min

    2006-01-01

    In this chapter we briefly review the developmental history and current research status of chloroplast transformation and introduce the merits of chloroplast transformation as compared with the nuclear genome transformation. Furthermore, according to the chloroplast transformation achieved in oilseed rape (Brassica napus), we introduce the preparation of explants, transformation methods, system selection, identification methods of the transplastomic plants, and experimental results. The technical points, the bottleneck, and the further research directions of the chloroplast transformation are discussed in the notes.

  14. Fault diagnosis of rolling bearings based on multifractal detrended fluctuation analysis and Mahalanobis distance criterion

    NASA Astrophysics Data System (ADS)

    Lin, Jinshan; Chen, Qian

    2013-07-01

    Vibration data of faulty rolling bearings are usually nonstationary and nonlinear, and contain fairly weak fault features. As a result, feature extraction of rolling bearing fault data is always an intractable problem and has attracted considerable attention for a long time. This paper introduces multifractal detrended fluctuation analysis (MF-DFA) to analyze bearing vibration data and proposes a novel method for fault diagnosis of rolling bearings based on MF-DFA and Mahalanobis distance criterion (MDC). MF-DFA, an extension of monofractal DFA, is a powerful tool for uncovering the nonlinear dynamical characteristics buried in nonstationary time series and can capture minor changes of complex system conditions. To begin with, by MF-DFA, multifractality of bearing fault data was quantified with the generalized Hurst exponent, the scaling exponent and the multifractal spectrum. Consequently, controlled by essentially different dynamical mechanisms, the multifractality of four heterogeneous bearing fault data is significantly different; by contrast, controlled by slightly different dynamical mechanisms, the multifractality of homogeneous bearing fault data with different fault diameters is significantly or slightly different depending on different types of bearing faults. Therefore, the multifractal spectrum, as a set of parameters describing multifractality of time series, can be employed to characterize different types and severity of bearing faults. Subsequently, five characteristic parameters sensitive to changes of bearing fault conditions were extracted from the multifractal spectrum and utilized to construct fault features of bearing fault data. Moreover, Hilbert transform based envelope analysis, empirical mode decomposition (EMD) and wavelet transform (WT) were utilized to study the same bearing fault data. Also, the kurtosis and the peak levels of the EMD or the WT component corresponding to the bearing tones in the frequency domain were carefully checked

  15. An underwater ship fault detection method based on Sonar image processing

    NASA Astrophysics Data System (ADS)

    Hong, Shi; Fang-jian, Shan; Bo, Cong; Wei, Qiu

    2016-02-01

    For the research of underwater ship fault detection method in conditions of sailing on the ocean especially in poor visibility muddy sea, a fault detection method under the assist of sonar image processing was proposed. Firstly, did sonar image denoising using the algorithm of pulse coupled neural network (PCNN); secondly, edge feature extraction for the image after denoising was carried out by morphological wavelet transform; Finally, interested regions Using relevant tracking method were taken, namely fault area mapping. The simulation results presented here proved the feasibility and effectiveness of the sonar image processing in underwater fault detection system.

  16. Closure of the Africa-Eurasia-North America plate motion circuit and tectonics of the Gloria fault

    NASA Technical Reports Server (NTRS)

    Argus, Donald F.; Gordon, Richard G.; Demets, Charles; Stein, Seth

    1989-01-01

    The current motions of the African, Eurasian, and North American plates are examined. The problems addressed include whether there is resolvable motion of a Spitsbergen microplate, the direction of motion between the African and North American plates, whether the Gloria fault is an active transform fault, and the implications of plate circuit closures for rates of intraplate deformation. Marine geophysical data and magnetic profiles are used to construct a model which predicts about 4 mm/yr slip across the Azores-Gibraltar Ridge, and west-northwest convergence near Gibraltar. The analyzed data are consistent with a rigid plate model with the Gloria fault being a transform fault.

  17. Kinematics and Fault Interaction of the Marmara Segment of the North Anatolian Fault Zone from Fault-Plane Solutions Based on a Refined High Precision Hypocenter Catalogue

    NASA Astrophysics Data System (ADS)

    Wollin, C.; Bohnhoff, M.; Küpperkoch, L.

    2015-12-01

    The North Anatolian Fault Zone (NAFZ) is separating the Eurasian and Anatolian plates representing a right-lateral transform plate boundary accommodating 20-30 mm annual slip. During the last seismic cycle the NAFZ has produced a series of large earthquakes that started in 1939 in Eastern Anatolia and has propagated westward towards the Istanbul-Marmara region. Here an up to 150 km long segment below the Sea of Marmara remains the only NAFZ segment that was not activated since 1766 representing a seismic gap hosting the potential for a magnitude up to 7.5 earthquake.Here we present a hypocenter catalogue for the Marmara section of the NAFZ which is a challenge since the fault is located offshore permitting no long-term on- or near fault stations. Using the Akaike Information Criterion applied on a characteristic function derived from higher order statistics as well as autoregressive forward prediction to automatically pick P- and S-onset times, we consistently analyze extensive waveform data provided by permanent seismic broadband stations of a combined regional seismic network with unprecedented station distribution.The quality of automatically determined travel times is carefully examined by comparing them to manual reference picks which were determined with a scheme emphasizing highest possible consistency and precision. The high accuracy obtained for the travel times results in an improved hypocenter catalog with fewer but well-located events that allow to image the major fault branches of the NAFZ below the Sea of Marmara.The large network aperture with lacking stations immediately above the seismicity along the fault and insufficient azimuthal station density prevents inversion for focal mechanisms of most single events. Therefore we form spatial seismicity clusters and calculate composite fault plane solutions. Resolving fault-zone geometry and kinematics allow to identify the currently active fault branches and to determine the currently ongoing processes

  18. Fault intersections along the Hosgri Fault Zone, Central California

    NASA Astrophysics Data System (ADS)

    Watt, J. T.; Johnson, S. Y.; Langenheim, V. E.

    2011-12-01

    It is well-established that stresses concentrate at fault intersections or bends when subjected to tectonic loading, making focused studies of these areas particularly important for seismic hazard analysis. In addition, detailed fault models can be used to investigate how slip on one fault might transfer to another during an earthquake. We combine potential-field, high-resolution seismic-reflection, and multibeam bathymetry data with existing geologic and seismicity data to investigate the fault geometry and connectivity of the Hosgri, Los Osos, and Shoreline faults offshore of San Luis Obispo, California. The intersection of the Hosgri and Los Osos faults in Estero Bay is complex. The offshore extension of the Los Osos fault, as imaged with multibeam and high-resolution seismic data, is characterized by a west-northwest-trending zone (1-3 km wide) of near vertical faulting. Three distinct strands (northern, central, and southern) are visible on shallow seismic reflection profiles. The steep dip combined with dramatic changes in reflection character across mapped faults within this zone suggests horizontal offset of rock units and argues for predominantly strike-slip motion, however, the present orientation of the fault zone suggests oblique slip. As the Los Osos fault zone approaches the Hosgri fault, the northern and central strands become progressively more northwest-trending in line with the Hosgri fault. The northern strand runs subparallel to the Hosgri fault along the edge of a long-wavelength magnetic anomaly, intersecting the Hosgri fault southwest of Point Estero. Geophysical modeling suggests the northern strand dips 70° to the northeast, which is in agreement with earthquake focal mechanisms that parallel this strand. The central strand bends northward and intersects the Hosgri fault directly west of Morro Rock, corresponding to an area of compressional deformation visible in shallow seismic-reflection profiles. The southern strand of the Los Osos

  19. Abnormal fault-recovery characteristics of the fault-tolerant multiprocessor uncovered using a new fault-injection methodology

    NASA Technical Reports Server (NTRS)

    Padilla, Peter A.

    1991-01-01

    An investigation was made in AIRLAB of the fault handling performance of the Fault Tolerant MultiProcessor (FTMP). Fault handling errors detected during fault injection experiments were characterized. In these fault injection experiments, the FTMP disabled a working unit instead of the faulted unit once in every 500 faults, on the average. System design weaknesses allow active faults to exercise a part of the fault management software that handles Byzantine or lying faults. Byzantine faults behave such that the faulted unit points to a working unit as the source of errors. The design's problems involve: (1) the design and interface between the simplex error detection hardware and the error processing software, (2) the functional capabilities of the FTMP system bus, and (3) the communication requirements of a multiprocessor architecture. These weak areas in the FTMP's design increase the probability that, for any hardware fault, a good line replacement unit (LRU) is mistakenly disabled by the fault management software.

  20. Abnormal fault-recovery characteristics of the fault-tolerant multiprocessor uncovered using a new fault-injection methodology

    NASA Astrophysics Data System (ADS)

    Padilla, Peter A.

    1991-03-01

    An investigation was made in AIRLAB of the fault handling performance of the Fault Tolerant MultiProcessor (FTMP). Fault handling errors detected during fault injection experiments were characterized. In these fault injection experiments, the FTMP disabled a working unit instead of the faulted unit once in every 500 faults, on the average. System design weaknesses allow active faults to exercise a part of the fault management software that handles Byzantine or lying faults. Byzantine faults behave such that the faulted unit points to a working unit as the source of errors. The design's problems involve: (1) the design and interface between the simplex error detection hardware and the error processing software, (2) the functional capabilities of the FTMP system bus, and (3) the communication requirements of a multiprocessor architecture. These weak areas in the FTMP's design increase the probability that, for any hardware fault, a good line replacement unit (LRU) is mistakenly disabled by the fault management software.

  1. Status of superconducting power transformer development

    SciTech Connect

    Johnson, R.C.; McConnell, B.W.; Mehta, S.P.

    1996-03-01

    Development of the superconducting transformer is arguably the most difficult of the ac power applications of superconductivity - this is because of the need for very low ac losses, adequate fault and surge performance, and the rigors of the application environment. This paper briefly summarizes the history of superconducting transformer projects, reviews the key issues for superconducting transformers, and examines the status of HTS transformer development. Both 630-kVA, three-phase and 1-MVA single phase demonstration units are expected to operate in late 1996. Both efforts will further progress toward the development of economical and performance competitive superconducting transformers.

  2. Holocene faulting on the Mission fault, northwest Montana

    SciTech Connect

    Ostenaa, D.A.; Klinger, R.E.; Levish, D.R. )

    1993-04-01

    South of Flathead Lake, fault scarps on late Quaternary surfaces are nearly continuous for 45 km along the western flank of the Mission Range. On late Pleistocene alpine lateral moraines, scarp heights reach a maximum of 17 m. Scarp heights on post glacial Lake Missoula surfaces range from 2.6--7.2 m and maximum scarp angles range from 10[degree]--24[degree]. The stratigraphy exposed in seven trenches across the fault demonstrates that the post glacial Lake Missoula scarps resulted from at least two surface-faulting events. Larger scarp heights on late Pleistocene moraines suggests a possible third event. This yields an estimated recurrence of 4--8 kyr. Analyses of scarp profiles show that the age of the most surface faulting is middle Holocene, consistent with stratigraphic evidence found in the trenches. Rupture length and displacement imply earthquake magnitudes of 7 to 7.5. Previous studies have not identified geologic evidence of late Quaternary surface faulting in the Rocky Mountain Trench or on faults north of the Lewis and Clark line despite abundant historic seismicity in the Flathead Lake area. In addition to the Mission fault, reconnaissance studies have located late Quaternary fault scarps along portions of faults bordering Jocko and Thompson Valleys. These are the first documented late Pleistocene/Holocene faults north of the Lewis and Clark line in Montana and should greatly revise estimates of earthquake hazards in this region.

  3. Randomness fault detection system

    NASA Technical Reports Server (NTRS)

    Russell, B. Don (Inventor); Aucoin, B. Michael (Inventor); Benner, Carl L. (Inventor)

    1996-01-01

    A method and apparatus are provided for detecting a fault on a power line carrying a line parameter such as a load current. The apparatus monitors and analyzes the load current to obtain an energy value. The energy value is compared to a threshold value stored in a buffer. If the energy value is greater than the threshold value a counter is incremented. If the energy value is greater than a high value threshold or less than a low value threshold then a second counter is incremented. If the difference between two subsequent energy values is greater than a constant then a third counter is incremented. A fault signal is issued if the counter is greater than a counter limit value and either the second counter is greater than a second limit value or the third counter is greater than a third limit value.

  4. Managing Fault Management Development

    NASA Technical Reports Server (NTRS)

    McDougal, John M.

    2010-01-01

    As the complexity of space missions grows, development of Fault Management (FM) capabilities is an increasingly common driver for significant cost overruns late in the development cycle. FM issues and the resulting cost overruns are rarely caused by a lack of technology, but rather by a lack of planning and emphasis by project management. A recent NASA FM Workshop brought together FM practitioners from a broad spectrum of institutions, mission types, and functional roles to identify the drivers underlying FM overruns and recommend solutions. They identified a number of areas in which increased program and project management focus can be used to control FM development cost growth. These include up-front planning for FM as a distinct engineering discipline; managing different, conflicting, and changing institutional goals and risk postures; ensuring the necessary resources for a disciplined, coordinated approach to end-to-end fault management engineering; and monitoring FM coordination across all mission systems.

  5. Construction and selection of lifting-based multiwavelets for mechanical fault detection

    NASA Astrophysics Data System (ADS)

    Yuan, Jing; He, Zhengjia; Zi, Yanyang; Wei, Ying

    2013-11-01

    The essence of wavelet transforms is a similar measurement between the signal and the wavelet basis functions. Thus, the construction and selection of the proper wavelet basis functions similar to the fault feature and possessing good properties such as vanishing moments have vital importance to the effective fault diagnosis. In this paper, the construction of lifting-based adaptive multiwavelets with various vanishing moments and the selection rules for different mechanical fault detection are proposed. On the basis of the fixed cubic Hermite multiwavelets, lifting schemes are adopted to construct new changeable multiwavelets with diverse vanishing moments. Then, the defined local spectral entropy minimization rules are proposed to determine the optimum multiwavelets providing the proper vanishing moments, classified into the typical shaft faults, gear faults and rolling bearing faults. The proposed method is applied to incipient fault diagnosis of rolling bearing and gearbox fault diagnosis of rolling mill to verify its effectiveness and feasibility in comparison with different wavelet transforms and spectral kurtosis. The results show that the proposed method can act as a promising tool for mechanical fault detection.

  6. Fault tolerant control laws

    NASA Technical Reports Server (NTRS)

    Ly, U. L.; Ho, J. K.

    1986-01-01

    A systematic procedure for the synthesis of fault tolerant control laws to actuator failure has been presented. Two design methods were used to synthesize fault tolerant controllers: the conventional LQ design method and a direct feedback controller design method SANDY. The latter method is used primarily to streamline the full-state Q feedback design into a practical implementable output feedback controller structure. To achieve robustness to control actuator failure, the redundant surfaces are properly balanced according to their control effectiveness. A simple gain schedule based on the landing gear up/down logic involving only three gains was developed to handle three design flight conditions: Mach .25 and Mach .60 at 5000 ft and Mach .90 at 20,000 ft. The fault tolerant control law developed in this study provides good stability augmentation and performance for the relaxed static stability aircraft. The augmented aircraft responses are found to be invariant to the presence of a failure. Furthermore, single-loop stability margins of +6 dB in gain and +30 deg in phase were achieved along with -40 dB/decade rolloff at high frequency.

  7. Seismic Hazard and Fault Length

    NASA Astrophysics Data System (ADS)

    Black, N. M.; Jackson, D. D.; Mualchin, L.

    2005-12-01

    If mx is the largest earthquake magnitude that can occur on a fault, then what is mp, the largest magnitude that should be expected during the planned lifetime of a particular structure? Most approaches to these questions rely on an estimate of the Maximum Credible Earthquake, obtained by regression (e.g. Wells and Coppersmith, 1994) of fault length (or area) and magnitude. Our work differs in two ways. First, we modify the traditional approach to measuring fault length, to allow for hidden fault complexity and multi-fault rupture. Second, we use a magnitude-frequency relationship to calculate the largest magnitude expected to occur within a given time interval. Often fault length is poorly defined and multiple faults rupture together in a single event. Therefore, we need to expand the definition of a mapped fault length to obtain a more accurate estimate of the maximum magnitude. In previous work, we compared fault length vs. rupture length for post-1975 earthquakes in Southern California. In this study, we found that mapped fault length and rupture length are often unequal, and in several cases rupture broke beyond the previously mapped fault traces. To expand the geologic definition of fault length we outlined several guidelines: 1) if a fault truncates at young Quaternary alluvium, the fault line should be inferred underneath the younger sediments 2) faults striking within 45° of one another should be treated as a continuous fault line and 3) a step-over can link together faults at least 5 km apart. These definitions were applied to fault lines in Southern California. For example, many of the along-strike faults lines in the Mojave Desert are treated as a single fault trending from the Pinto Mountain to the Garlock fault. In addition, the Rose Canyon and Newport-Inglewood faults are treated as a single fault line. We used these more generous fault lengths, and the Wells and Coppersmith regression, to estimate the maximum magnitude (mx) for the major faults in

  8. Three-dimensional models of deformation near strike-slip faults

    USGS Publications Warehouse

    ten Brink, U.S.; Katzman, Rafael; Lin, J.

    1996-01-01

    overlapping en echelon faults, which can be misinterpreted to indicate a regional component of extension. Zones of subsidence or uplift can become wider than expected for transform plate boundaries when a minor component of oblique motion is added to a system of parallel strike-slip faults.

  9. Evaluation of feasibility of mapping seismically active faults in Alaska

    NASA Technical Reports Server (NTRS)

    Gedney, L. D.; Vanwormer, J. D. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. The sharp bend in the Alaska Range near 65 deg N, 150 deg W in now thought to enclose a corner of the northwesterly migrating north Pacific lithospheric plate. Subduction of the plate beneath the continent is believed, on the basis of hypocentral distribution, to occur along Cook Inlet and the eastern flanks of the Aleutian and Alaska Ranges as far northward as Mt. McKinley. The nature of tectonic deformation here, particularly in the area of the bend in the Alaska Range, is understandably complex. The Denali fault is thought to be a transform character in the vicinity of Mt. McKinley (i.e., it is thought to be the surface along which the oceanic plate separates from the continental plate). On the ERTS-1 imagery, however, it appears that there are a number of sub-parallel faults which branch off of the Denali fault in a southwesterly direction. Slippage along these would tend to squeeze material around the inside of the band rather than the plate being directly underthrust. All of these sub-parallel faults are seismically active. The right-lateral fault-plane solution obtained for this event is consistent with the concept of slippage around the bend on a set of sub-parallel faults in the manner postulated. The best images to show these features are 1066-20444 and 1266-20572.

  10. Simultaneous-Fault Diagnosis of Gearboxes Using Probabilistic Committee Machine

    PubMed Central

    Zhong, Jian-Hua; Wong, Pak Kin; Yang, Zhi-Xin

    2016-01-01

    This study combines signal de-noising, feature extraction, two pairwise-coupled relevance vector machines (PCRVMs) and particle swarm optimization (PSO) for parameter optimization to form an intelligent diagnostic framework for gearbox fault detection. Firstly, the noises of sensor signals are de-noised by using the wavelet threshold method to lower the noise level. Then, the Hilbert-Huang transform (HHT) and energy pattern calculation are applied to extract the fault features from de-noised signals. After that, an eleven-dimension vector, which consists of the energies of nine intrinsic mode functions (IMFs), maximum value of HHT marginal spectrum and its corresponding frequency component, is obtained to represent the features of each gearbox fault. The two PCRVMs serve as two different fault detection committee members, and they are trained by using vibration and sound signals, respectively. The individual diagnostic result from each committee member is then combined by applying a new probabilistic ensemble method, which can improve the overall diagnostic accuracy and increase the number of detectable faults as compared to individual classifiers acting alone. The effectiveness of the proposed framework is experimentally verified by using test cases. The experimental results show the proposed framework is superior to existing single classifiers in terms of diagnostic accuracies for both single- and simultaneous-faults in the gearbox. PMID:26848665

  11. Simultaneous-Fault Diagnosis of Gearboxes Using Probabilistic Committee Machine.

    PubMed

    Zhong, Jian-Hua; Wong, Pak Kin; Yang, Zhi-Xin

    2016-01-01

    This study combines signal de-noising, feature extraction, two pairwise-coupled relevance vector machines (PCRVMs) and particle swarm optimization (PSO) for parameter optimization to form an intelligent diagnostic framework for gearbox fault detection. Firstly, the noises of sensor signals are de-noised by using the wavelet threshold method to lower the noise level. Then, the Hilbert-Huang transform (HHT) and energy pattern calculation are applied to extract the fault features from de-noised signals. After that, an eleven-dimension vector, which consists of the energies of nine intrinsic mode functions (IMFs), maximum value of HHT marginal spectrum and its corresponding frequency component, is obtained to represent the features of each gearbox fault. The two PCRVMs serve as two different fault detection committee members, and they are trained by using vibration and sound signals, respectively. The individual diagnostic result from each committee member is then combined by applying a new probabilistic ensemble method, which can improve the overall diagnostic accuracy and increase the number of detectable faults as compared to individual classifiers acting alone. The effectiveness of the proposed framework is experimentally verified by using test cases. The experimental results show the proposed framework is superior to existing single classifiers in terms of diagnostic accuracies for both single- and simultaneous-faults in the gearbox. PMID:26848665

  12. Simultaneous-Fault Diagnosis of Gearboxes Using Probabilistic Committee Machine.

    PubMed

    Zhong, Jian-Hua; Wong, Pak Kin; Yang, Zhi-Xin

    2016-02-02

    This study combines signal de-noising, feature extraction, two pairwise-coupled relevance vector machines (PCRVMs) and particle swarm optimization (PSO) for parameter optimization to form an intelligent diagnostic framework for gearbox fault detection. Firstly, the noises of sensor signals are de-noised by using the wavelet threshold method to lower the noise level. Then, the Hilbert-Huang transform (HHT) and energy pattern calculation are applied to extract the fault features from de-noised signals. After that, an eleven-dimension vector, which consists of the energies of nine intrinsic mode functions (IMFs), maximum value of HHT marginal spectrum and its corresponding frequency component, is obtained to represent the features of each gearbox fault. The two PCRVMs serve as two different fault detection committee members, and they are trained by using vibration and sound signals, respectively. The individual diagnostic result from each committee member is then combined by applying a new probabilistic ensemble method, which can improve the overall diagnostic accuracy and increase the number of detectable faults as compared to individual classifiers acting alone. The effectiveness of the proposed framework is experimentally verified by using test cases. The experimental results show the proposed framework is superior to existing single classifiers in terms of diagnostic accuracies for both single- and simultaneous-faults in the gearbox.

  13. Fault management for data systems

    NASA Technical Reports Server (NTRS)

    Boyd, Mark A.; Iverson, David L.; Patterson-Hine, F. Ann

    1993-01-01

    Issues related to automating the process of fault management (fault diagnosis and response) for data management systems are considered. Substantial benefits are to be gained by successful automation of this process, particularly for large, complex systems. The use of graph-based models to develop a computer assisted fault management system is advocated. The general problem is described and the motivation behind choosing graph-based models over other approaches for developing fault diagnosis computer programs is outlined. Some existing work in the area of graph-based fault diagnosis is reviewed, and a new fault management method which was developed from existing methods is offered. Our method is applied to an automatic telescope system intended as a prototype for future lunar telescope programs. Finally, an application of our method to general data management systems is described.

  14. Relative tectonic activity assessment along the East Anatolian strike-slip fault, Eastern Turkey

    NASA Astrophysics Data System (ADS)

    Khalifa, Abdelrahman

    2016-04-01

    The East Anatolian transform fault is a morphologically distinct and seismically active left-lateral strike-slip fault that extends for ~ 500 km from Karlıova to the Maraş defining the boundary between the Anatolian Block and Syrian Foreland. Deformed landforms along the East Anatolian fault provide important insights into the nature of landscape development within an intra-continental strike-slip fault system. Geomorphic analysis of the East Anatolian fault using geomorphic indices including mountain front sinuosity, stream length-gradient index, drainage density, hypsometric integral, and the valley-width to valley height ratio helped differentiate the faulting into segments of differing degrees of the tectonic and geomorphic activity. Watershed maps for the East Anatolian fault showing the relative relief, incision, and maturity of basins along the fault zone help define segments of the higher seismic risk and help evaluate the regional seismic hazard. The results of the geomorphic indices show a high degree of activity, reveal each segment along the fault is active and represent a higher seismic hazard along the entire fault.

  15. Fault tolerant massively parallel processing architecture

    SciTech Connect

    Balasubramanian, V.; Banerjee, P.

    1987-08-01

    This paper presents two massively parallel processing architectures suitable for solving a wide variety of algorithms of divide-and-conquer type for problems such as the discrete Fourier transform, production systems, design automation, and others. The first architecture, called the Chain-structured Butterfly ARchitecture (CBAR), consists of a two-dimensional array of N-L . (log/sub 2/(L)+1) processing elements (PE) organized as L levels of log/sub 2/(L)+1 stages, and which has the butterfly connection between PEs in consecutive stages with straight-through feedback between PEs in the last and first stages. This connection system has the desirable property of allowing thousands of PEs to be connected with O(N) connection cost, O(log/sub 2/(N/log/sub 2/N)) communication paths, and a small number (=4) of I/O ports per PE. However, this architecture is not fault tolerant. The authors, therefore, propose a second architecture, called the REconfigurable Chain-structured Butterfly ARchitecture (RECBAR), which is a modified version of the CBAR. The RECBAR possesses all the desirable features of the CBAR, with the number of I/O ports per PE increased to six, and uses O(log/sub 2/N)/N) overhead in PEs and approximately 50% overhead in links to achieve single-level fault tolerance. Reliability improvements of the RECBAR over the CBAR are studied. This paper also presents a distributed diagnostic and structuring algorithm for the RECBAR that enables the architecture to detect faults and structure itself accordingly within 2 . log/sub 2/(L)+1 time steps, thus making it a truly fault tolerant architecture.

  16. Fault-tolerant multiprocessor computer

    SciTech Connect

    Smith, T.B. III; Lala, J.H.; Goldberg, J.; Kautz, W.H.; Melliar-Smith, P.M.; Green, M.W.; Levitt, K.N.; Schwartz, R.L.; Weinstock, C.B.; Palumbo, D.L.

    1986-01-01

    The development and evaluation of fault-tolerant computer architectures and software-implemented fault tolerance (SIFT) for use in advanced NASA vehicles and potentially in flight-control systms are described in a collection of previously published reports prepared for NASA. Topics addressed include the principles of fault-tolerant multiprocessor (FTMP) operation; processor and slave regional designs; FTMP executive, facilities, aceptance-test/diagnostic, applications, and support software; FTM reliability and availability models; SIFT hardware design; and SIFT validation and verification.

  17. Fault-tolerant processing system

    NASA Technical Reports Server (NTRS)

    Palumbo, Daniel L. (Inventor)

    1996-01-01

    A fault-tolerant, fiber optic interconnect, or backplane, which serves as a via for data transfer between modules. Fault tolerance algorithms are embedded in the backplane by dividing the backplane into a read bus and a write bus and placing a redundancy management unit (RMU) between the read bus and the write bus so that all data transmitted by the write bus is subjected to the fault tolerance algorithms before the data is passed for distribution to the read bus. The RMU provides both backplane control and fault tolerance.

  18. SEISMOLOGY: Watching the Hayward Fault.

    PubMed

    Simpson, R W

    2000-08-18

    The Hayward fault, located on the east side of the San Francisco Bay, represents a natural laboratory for seismologists, because it does not sleep silently between major earthquakes. In his Perspective, Simpson discusses the study by Bürgmann et al., who have used powerful new techniques to study the fault. The results indicate that major earthquakes cannot originate in the northern part of the fault. However, surface-rupturing earthquakes have occurred in the area, suggesting that they originated to the north or south of the segment studied by Bürgmann et al. Fundamental questions remain regarding the mechanism by which plate tectonic stresses are transferred to the Hayward fault.

  19. Fault interaction near Hollister, California

    NASA Astrophysics Data System (ADS)

    Mavko, Gerald M.

    1982-09-01

    A numerical model is used to study fault stress and slip near Hollister, California. The geometrically complex system of interacting faults, including the San Andreas, Calaveras, Sargent, and Busch faults, is approximated with a two-dimensional distribution of short planar fault segments in an elastic medium. The steady stress and slip rate are simulated by specifying frictional strength and stepping the remote stress ahead in time. The resulting computed fault stress is roughly proportional to the observed spatial density of small earthquakes, suggesting that the distinction between segments characterized by earthquakes and those with aseismic creep results, in part, from geometry. A nosteady simulation is made by introducing, in addition, stress drops for individual moderate earthquakes. A close fit of observed creep with calculated slip on the Calaveras and San Andreas faults suggests that many changes in creep rate (averaged over several months) are caused by local moderate earthquakes. In particular, a 3-year creep lag preceding the August 6, 1979, Coyote Lake earthquake on the Calaveras fault seems to have been a direct result of the November 28, 1974, Thanksgiving Day earthquake on the Busch fault. Computed lags in slip rate preceding some other moderate earthquakes in the area are also due to earlier earthquakes. Although the response of the upper 1 km of the fault zone may cause some individual creep events and introduce delays in others, the long-term rate appears to reflect deep slip.

  20. Fault interaction near Hollister, California

    SciTech Connect

    Mavko, G.M.

    1982-09-10

    A numerical model is used to study fault stress slip near Hollister, California. The geometrically complex system of interacting faults, including the San Andreas, Calaveras, Sargent, and Busch faults, is approximated with a two-dimensional distribution of short planar fault segments in an elastic medium. The steady stress and slip rate are simulated by specifying frictional strength and stepping the remote stress ahead in time. The resulting computed fault stress is roughly proportional to the observed spatial density of small earthquakes, suggesting that the distinction between segments characterized by earthquakes and those with aseismic creep results, in part, from geometry. A nonsteady simulation is made by introducing, in addition, stress drops for individual moderate earthquakes. A close fit of observed creep with calculated slip on the Calaveras and San Andreas faults suggests that many changes in creep rate (averaged over several months) are caused by local moderate earthquakes. In particular, a 3-year creep lag preceding the August 6, 1979, Coyote Lake earthquake on the Calaveras fault seems to have been a direct result of the November 28, 1974, Thanksgiving Day earthquake on the Busch fault. Computed lags in slip rate preceding some other moderate earthquakes in the area are also due to earlier earthquakes. Although the response of the upper 1 km of the fault zone may cause some individual creep events and introduce delays in others, the long-term rate appears to reflect deep slip.

  1. Fault-Tree Compiler Program

    NASA Technical Reports Server (NTRS)

    Butler, Ricky W.; Martensen, Anna L.

    1992-01-01

    FTC, Fault-Tree Compiler program, is reliability-analysis software tool used to calculate probability of top event of fault tree. Five different types of gates allowed in fault tree: AND, OR, EXCLUSIVE OR, INVERT, and M OF N. High-level input language of FTC easy to understand and use. Program supports hierarchical fault-tree-definition feature simplifying process of description of tree and reduces execution time. Solution technique implemented in FORTRAN, and user interface in Pascal. Written to run on DEC VAX computer operating under VMS operating system.

  2. Final Technical Report: PV Fault Detection Tool.

    SciTech Connect

    King, Bruce Hardison; Jones, Christian Birk

    2015-12-01

    The PV Fault Detection Tool project plans to demonstrate that the FDT can (a) detect catastrophic and degradation faults and (b) identify the type of fault. This will be accomplished by collecting fault signatures using different instruments and integrating this information to establish a logical controller for detecting, diagnosing and classifying each fault.

  3. 20 CFR 404.507 - Fault.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Officer § 404.507 Fault. Fault as used in without fault (see § 404.506 and 42 CFR 405.355) applies only to the individual. Although the Administration may have been at fault in making the overpayment, that... 20 Employees' Benefits 2 2011-04-01 2011-04-01 false Fault. 404.507 Section 404.507...

  4. 20 CFR 404.507 - Fault.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Officer § 404.507 Fault. Fault as used in without fault (see § 404.506 and 42 CFR 405.355) applies only to the individual. Although the Administration may have been at fault in making the overpayment, that... 20 Employees' Benefits 2 2013-04-01 2013-04-01 false Fault. 404.507 Section 404.507...

  5. 20 CFR 404.507 - Fault.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Officer § 404.507 Fault. Fault as used in without fault (see § 404.506 and 42 CFR 405.355) applies only to the individual. Although the Administration may have been at fault in making the overpayment, that... 20 Employees' Benefits 2 2012-04-01 2012-04-01 false Fault. 404.507 Section 404.507...

  6. 20 CFR 404.507 - Fault.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Officer § 404.507 Fault. Fault as used in without fault (see § 404.506 and 42 CFR 405.355) applies only to the individual. Although the Administration may have been at fault in making the overpayment, that... 20 Employees' Benefits 2 2014-04-01 2014-04-01 false Fault. 404.507 Section 404.507...

  7. 20 CFR 404.507 - Fault.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Officer § 404.507 Fault. Fault as used in without fault (see § 404.506 and 42 CFR 405.355) applies only to the individual. Although the Administration may have been at fault in making the overpayment, that... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false Fault. 404.507 Section 404.507...

  8. Cross-Cutting Faults

    NASA Technical Reports Server (NTRS)

    2005-01-01

    16 May 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows cross-cutting fault scarps among graben features in northern Tempe Terra. Graben form in regions where the crust of the planet has been extended; such features are common in the regions surrounding the vast 'Tharsis Bulge' on Mars.

    Location near: 43.7oN, 90.2oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Summer

  9. Fault current limiter

    DOEpatents

    Darmann, Francis Anthony

    2013-10-08

    A fault current limiter (FCL) includes a series of high permeability posts for collectively define a core for the FCL. A DC coil, for the purposes of saturating a portion of the high permeability posts, surrounds the complete structure outside of an enclosure in the form of a vessel. The vessel contains a dielectric insulation medium. AC coils, for transporting AC current, are wound on insulating formers and electrically interconnected to each other in a manner such that the senses of the magnetic field produced by each AC coil in the corresponding high permeability core are opposing. There are insulation barriers between phases to improve dielectric withstand properties of the dielectric medium.

  10. Geomorphic mapping of the southern Maacama fault based on LiDAR data

    NASA Astrophysics Data System (ADS)

    Hoeft, J. S.; Sowers, J. M.; Kelsey, H. M.; Prentice, C. S.; Frankel, K. L.

    2008-12-01

    The Maacama fault is an active strike slip fault, and a potentially significant seismic source, within the San Andreas transform system. The fault is located east of and parallel to the San Andreas fault in Sonoma and Mendocino counties, California and is divided into a northern and southern section based on a NW to NNW change in strike. The southern segment comprises 54 km of the fault's 144 km total length and is primarily located in an upland area traversing mountainous terrain. Strain is thought to transfer northward from the East Bay fault zone along the Rodgers Creek fault and, through a right step, to the Maacama fault. LiDAR data collected in a 1-km-wide swath along the southern Maacama fault, as part of the GeoEarthscope project, were used to produce a bare-earth digital elevation model, from which hillshade, topographic contour, slope, and curvature maps with 0.5- to 1-m-resolution were derived. Mapping was primarily conducted digitally in a GIS environment, and interpretation of LiDAR data was supplemented with aerial photograph interpretation and field inspection. Primary, Holocene-age fault-related geomorphic features, consisting of scarps and dextrally offset drainages, define the southern Maacama. These features are sparsely distributed and comprise less than 20% of the fault length. The fault scarps define a sequence of left-stepping, en echelon fault segments with an average segment length of 230 m. By contrast, the northern Maacama fault is better defined geomorphically. The poor expression of the southern Maacama is likely due to the presence of active hillslope processes and low levels of seismicity. Seismicity along the southern segment is lower than that of the northern segment. The Coast Range uplands, primarily composed of Franciscan Complex, is characterized by numerous landslides and experiences annual precipitation of 75 to 180 cm. There is approximately 30 km of overlap between the northern end of the Rodgers Creek fault and the southern

  11. AGSM Functional Fault Models for Fault Isolation Project

    NASA Technical Reports Server (NTRS)

    Harp, Janicce Leshay

    2014-01-01

    This project implements functional fault models to automate the isolation of failures during ground systems operations. FFMs will also be used to recommend sensor placement to improve fault isolation capabilities. The project enables the delivery of system health advisories to ground system operators.

  12. Central Asia Active Fault Database

    NASA Astrophysics Data System (ADS)

    Mohadjer, Solmaz; Ehlers, Todd A.; Kakar, Najibullah

    2014-05-01

    The ongoing collision of the Indian subcontinent with Asia controls active tectonics and seismicity in Central Asia. This motion is accommodated by faults that have historically caused devastating earthquakes and continue to pose serious threats to the population at risk. Despite international and regional efforts to assess seismic hazards in Central Asia, little attention has been given to development of a comprehensive database for active faults in the region. To address this issue and to better understand the distribution and level of seismic hazard in Central Asia, we are developing a publically available database for active faults of Central Asia (including but not limited to Afghanistan, Tajikistan, Kyrgyzstan, northern Pakistan and western China) using ArcGIS. The database is designed to allow users to store, map and query important fault parameters such as fault location, displacement history, rate of movement, and other data relevant to seismic hazard studies including fault trench locations, geochronology constraints, and seismic studies. Data sources integrated into the database include previously published maps and scientific investigations as well as strain rate measurements and historic and recent seismicity. In addition, high resolution Quickbird, Spot, and Aster imagery are used for selected features to locate and measure offset of landforms associated with Quaternary faulting. These features are individually digitized and linked to attribute tables that provide a description for each feature. Preliminary observations include inconsistent and sometimes inaccurate information for faults documented in different studies. For example, the Darvaz-Karakul fault which roughly defines the western margin of the Pamir, has been mapped with differences in location of up to 12 kilometers. The sense of motion for this fault ranges from unknown to thrust and strike-slip in three different studies despite documented left-lateral displacements of Holocene and late

  13. Talc friction in the temperature range 25°–400 °C: relevance for fault-zone weakening

    USGS Publications Warehouse

    Moore, Diane E.; Lockner, David A.

    2008-01-01

    Talc has a temperature–pressure range of stability that extends from surficial to eclogite-facies conditions, making it of potential significance in a variety of faulting environments. Talc has been identified in exhumed subduction zone thrusts, in fault gouge collected from oceanic transform and detachment faults associated with rift systems, and recently in serpentinite from the central creeping section of the San Andreas fault. Typically, talc crystallized in the active fault zones as a result of the reaction of ultramafic rocks with silica-saturated hydrothermal fluids. This mode of formation of talc is a prime example of a fault-zone weakening process. Because of its velocity-strengthening behavior, talc may play a role in stabilizing slip at depth in subduction zones and in the creeping faults of central and northern California that are associated with ophiolitic rocks.

  14. Colorado Regional Faults

    SciTech Connect

    Hussein, Khalid

    2012-02-01

    Citation Information: Originator: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Originator: Colorado Geological Survey (CGS) Publication Date: 2012 Title: Regional Faults Edition: First Publication Information: Publication Place: Earth Science & Observation Center, Cooperative Institute for Research in Environmental Science, University of Colorado, Boulder Publisher: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Description: This layer contains the regional faults of Colorado Spatial Domain: Extent: Top: 4543192.100000 m Left: 144385.020000 m Right: 754585.020000 m Bottom: 4094592.100000 m Contact Information: Contact Organization: Earth Science &Observation Center (ESOC), CIRES, University of Colorado at Boulder Contact Person: Khalid Hussein Address: CIRES, Ekeley Building Earth Science & Observation Center (ESOC) 216 UCB City: Boulder State: CO Postal Code: 80309-0216 Country: USA Contact Telephone: 303-492-6782 Spatial Reference Information: Coordinate System: Universal Transverse Mercator (UTM) WGS’1984 Zone 13N False Easting: 500000.00000000 False Northing: 0.00000000 Central Meridian: -105.00000000 Scale Factor: 0.99960000 Latitude of Origin: 0.00000000 Linear Unit: Meter Datum: World Geodetic System 1984 (WGS ’984) Prime Meridian: Greenwich Angular Unit: Degree Digital Form: Format Name: Shape file

  15. SFT: Scalable Fault Tolerance

    SciTech Connect

    Petrini, Fabrizio; Nieplocha, Jarek; Tipparaju, Vinod

    2006-04-15

    In this paper we will present a new technology that we are currently developing within the SFT: Scalable Fault Tolerance FastOS project which seeks to implement fault tolerance at the operating system level. Major design goals include dynamic reallocation of resources to allow continuing execution in the presence of hardware failures, very high scalability, high efficiency (low overhead), and transparency—requiring no changes to user applications. Our technology is based on a global coordination mechanism, that enforces transparent recovery lines in the system, and TICK, a lightweight, incremental checkpointing software architecture implemented as a Linux kernel module. TICK is completely user-transparent and does not require any changes to user code or system libraries; it is highly responsive: an interrupt, such as a timer interrupt, can trigger a checkpoint in as little as 2.5μs; and it supports incremental and full checkpoints with minimal overhead—less than 6% with full checkpointing to disk performed as frequently as once per minute.

  16. Fault Management Design Strategies

    NASA Technical Reports Server (NTRS)

    Day, John C.; Johnson, Stephen B.

    2014-01-01

    Development of dependable systems relies on the ability of the system to determine and respond to off-nominal system behavior. Specification and development of these fault management capabilities must be done in a structured and principled manner to improve our understanding of these systems, and to make significant gains in dependability (safety, reliability and availability). Prior work has described a fundamental taxonomy and theory of System Health Management (SHM), and of its operational subset, Fault Management (FM). This conceptual foundation provides a basis to develop framework to design and implement FM design strategies that protect mission objectives and account for system design limitations. Selection of an SHM strategy has implications for the functions required to perform the strategy, and it places constraints on the set of possible design solutions. The framework developed in this paper provides a rigorous and principled approach to classifying SHM strategies, as well as methods for determination and implementation of SHM strategies. An illustrative example is used to describe the application of the framework and the resulting benefits to system and FM design and dependability.

  17. Compound faults detection of rotating machinery using improved adaptive redundant lifting multiwavelet

    NASA Astrophysics Data System (ADS)

    Chen, Jinglong; Zi, Yanyang; He, Zhengjia; Yuan, Jing

    2013-07-01

    Due to the character of diversity and complexity, the compound faults detection of rotating machinery under non-stationary operation turns into a challenging task. Multiwavelet with two or more base functions and many excellent properties provides a possibility to detect and extract all the features of compound faults at one time. However, the fixed basis functions independent of the vibration signal may decrease the accuracy of fault detection. Moreover, the decomposition result of discrete multiwavelet transform does not possess time invariance, which is harmful to extract the feature of periodical impulses. To overcome these deficiencies, based on the Hermite splines interpolation, taking the minimum envelope spectrum entropy as the optimization objective, adaptive redundant lifting multiwavelet is developed. Additionally, in order to eliminate error propagation of decomposition results, adaptive redundant lifting multiwavelet is improved by adding the normalization factors. As an effective method, Hilbert transform demodulation analysis is used to extract the fault feature from the high frequency modulation signal. The proposed method incorporating improved adaptive redundant lifting multiwavelet (IARLM) with Hilbert transform demodulation analysis is applied to compound faults detection for the simulation experiment, rolling element bearing test bench and traveling unit of electric locomotive. Compared with some other fault detection methods, the results show the superior effectiveness and reliability on the compound faults detection.

  18. Adiabatic Quantum Programming: Minor Embedding With Hard Faults

    SciTech Connect

    Klymko, Christine F; Sullivan, Blair D; Humble, Travis S

    2013-01-01

    Adiabatic quantum programming defines the time-dependent mapping of a quantum algorithm into the hardware or logical fabric. An essential programming step is the embedding of problem-specific information into the logical fabric to define the quantum computational transformation. We present algorithms for embedding arbitrary instances of the adiabatic quantum optimization algorithm into a square lattice of specialized unit cells. Our methods are shown to be extensible in fabric growth, linear in time, and quadratic in logical footprint. In addition, we provide methods for accommodating hard faults in the logical fabric without invoking approximations to the original problem. These hard fault-tolerant embedding algorithms are expected to prove useful for benchmarking the adiabatic quantum optimization algorithm on existing quantum logical hardware. We illustrate this versatility through numerical studies of embeddabilty versus hard fault rates in square lattices of complete bipartite unit cells.

  19. Accelerometer having integral fault null

    NASA Technical Reports Server (NTRS)

    Bozeman, Richard J., Jr. (Inventor)

    1995-01-01

    An improved accelerometer is introduced. It comprises a transducer responsive to vibration in machinery which produces an electrical signal related to the magnitude and frequency of the vibration; and a decoding circuit responsive to the transducer signal which produces a first fault signal to produce a second fault signal in which ground shift effects are nullified.

  20. Paleoseismic and Geomorphic Evidence for Quaternary Fault Slip on the Central Range Fault, South American-Caribbean Plate Boundary, Trinidad

    NASA Astrophysics Data System (ADS)

    Prentice, C. S.; Weber, J.; Crosby, C. J.

    2001-12-01

    The island of Trinidad is located along the transform plate boundary between the South American and Caribbean plates. GPS measurements show that relative motion along this boundary is nearly E-W right-lateral shear (Weber et al., 2001). Analysis and comparison of historic triangulation and GPS data suggest that a significant fraction (14+/-3 mm/yr) of the total plate-boundary motion (about 20 mm/yr) is being accommodated across the Central Range Fault in central Trinidad. Our new paleoseismic studies demonstrate that Quaternary surface rupture has occurred on this previously unrecognized, historically aseismic, active fault. Geomorphic evidence of Quaternary faulting along the Central Range Fault includes linear drainages, aligned topographic saddles and troughs, offset ridges, right-laterally deflected streams, and linear scarps. We mapped these features using 1:20,000 scale aerial photographs and field reconnaissance along a 25-km-long section between Pointe-a-Pierre on the west coast and Navet Dam. Geomorphic features near Manzanilla Bay on the east coast suggest that the Central Range Fault continues across the island as a Quaternary feature for another 25 km to the northeast. Marine geophysical surveys suggest this fault continues offshore to the west (Warm Springs fault), and steps to the north across the Gulf of Paria pull-apart basin to the El Pilar Fault. The extent of the fault offshore to the east is unknown. We exposed a 6-m-wide shear zone within Pliocene(?) material in a trench cut into a fluvial terrace, south of Samlalsingh Road near Bonne Aventure. The overlying Quaternary fluvial gravel is faulted and folded across the shear zone, and Quaternary fluvial deposits are faulted against the shear zone on the north side. A second excavation across a prominent scarp near Tabaquite, 12 km northeast of Samlalsingh Road, exposed a colluvial wedge and overlying unfaulted sediments. We interpret the colluvial wedge to represent deposits shed off the scarp in

  1. Slip deficit and location of seismic gaps along the Dead Sea Fault

    NASA Astrophysics Data System (ADS)

    Meghraoui, Mustapha; Toussaint, Renaud; Ferry, Matthieu; Nguema-Edzang, Parfait

    2015-04-01

    The Dead Sea Fault (DSF), a ~ 1000-km-long North-South trending transform fault presents structural discontinuities and includes segments that experienced large earthquakes (Mw>7) in historical times. The Wadi Araba and Jordan Valley, the Lebanese restraining bend, the Missyaf and Ghab fault segments in Syria and the Ziyaret Fault segment in Turkey display geometrical complexities made of step overs, restraining and releasing bends that may constitute major obstacles to earthquake rupture propagation. Using active tectonics, GPS measurements and paleoseismology we investigate the kinematics and long-term/short-term slip rates along the Dead Sea fault. Tectonic geomorphology with paleoseismic trenching and archeoseismic investigations indicate repeated faulting events and left-lateral slip rate ranging from 4 mm/yr in the southern fault section to 6 mm/yr in the northern fault section. Except for the northernmost DSF section, these long-term estimates of fault slip rate are consistent with GPS measurements that show 4 to 5 mm/yr deformation rate across the plate boundary. Indeed, recent GPS results showing 3 +-0.5 mm/yr velocity rate of the northern DSF appear to be in contradiction with the ~6 mm/yr paleoseismic slip rate. The kinematic modeling that combines GPS and seismotectonic results implies a complex geodynamic pattern with the DSF transforms the Cyprus arc subduction zone into transpressive tectonics on the East Anatolian fault. The timing of past earthquake ruptures shows the occurrence of seismic sequences and a southward migration of large earthquakes, with the existence of major seismic gaps along strike. In this contribution, we present the calculated seismic slip deficit along the fault segments and discuss the identification of seismic gaps and the implication for the seismic hazard assessment.

  2. How do normal faults grow?

    NASA Astrophysics Data System (ADS)

    Jackson, Christopher; Bell, Rebecca; Rotevatn, Atle; Tvedt, Anette

    2016-04-01

    Normal faulting accommodates stretching of the Earth's crust, and it is arguably the most fundamental tectonic process leading to continent rupture and oceanic crust emplacement. Furthermore, the incremental and finite geometries associated with normal faulting dictate landscape evolution, sediment dispersal and hydrocarbon systems development in rifts. Displacement-length scaling relationships compiled from global datasets suggest normal faults grow via a sympathetic increase in these two parameters (the 'isolated fault model'). This model has dominated the structural geology literature for >20 years and underpins the structural and tectono-stratigraphic models developed for active rifts. However, relatively recent analysis of high-quality 3D seismic reflection data suggests faults may grow by rapid establishment of their near-final length prior to significant displacement accumulation (the 'coherent fault model'). The isolated and coherent fault models make very different predictions regarding the tectono-stratigraphic evolution of rift basin, thus assessing their applicability is important. To-date, however, very few studies have explicitly set out to critically test the coherent fault model thus, it may be argued, it has yet to be widely accepted in the structural geology community. Displacement backstripping is a simple graphical technique typically used to determine how faults lengthen and accumulate displacement; this technique should therefore allow us to test the competing fault models. However, in this talk we use several subsurface case studies to show that the most commonly used backstripping methods (the 'original' and 'modified' methods) are, however, of limited value, because application of one over the other requires an a priori assumption of the model most applicable to any given fault; we argue this is illogical given that the style of growth is exactly what the analysis is attempting to determine. We then revisit our case studies and demonstrate

  3. Multifractal entropy based adaptive multiwavelet construction and its application for mechanical compound-fault diagnosis

    NASA Astrophysics Data System (ADS)

    He, Shuilong; Chen, Jinglong; Zhou, Zitong; Zi, Yanyang; Wang, Yanxue; Wang, Xiaodong

    2016-08-01

    Compound-fault diagnosis of mechanical equipment is still challenging at present because of its complexity, multiplicity and non-stationarity. In this work, an adaptive redundant multiwavelet packet (ARMP) method is proposed for the compound-fault diagnosis. Multiwavelet transform has two or more base functions and many excellent properties, making it suitable for detecting all the features of compound-fault simultaneously. However, on the other hand, the fixed basis function used in multiwavelet transform may decrease the accuracy of fault extraction; what's more, the multi-resolution analysis of multiwavelet transform in low frequency band may also leave out the useful features. Thus, the minimum sum of normalized multifractal entropy is adopted as the optimization criteria for the proposed ARMP method, while the relative energy ratio of the characteristic frequency is utilized as an effective way in automatically selecting the sensitive frequency bands. Then, The ARMP technique combined with Hilbert transform demodulation analysis is then applied to detect the compound-fault of bevel gearbox and planetary gearbox. The results verify that the proposed method can effectively identify and detect the compound-fault of mechanical equipment.

  4. Characterizing Recent Slip on the Kuikui Fault, a Link Between the Green Valley and Bartlett Springs Fault Zones, Wilson Valley, Northern California.

    NASA Astrophysics Data System (ADS)

    Lienkaemper, J. J.; DeLong, S. B.; McPherson, R. C.; Mielke, J.; Avdievitch, N.; Pickering, A.; Lloyd, C.

    2014-12-01

    The Green Valley and Bartlett Springs faults (GVF-BSF) together form the third largest branch of the dextral San Andreas transform fault system in northern California. Wilson Valley lies at the center of a tectonic pull-apart basin formed in the 2.5-km stepover between the Hunting Creek fault (northernmost section of the GVF) and the Highway-20 section of the BSF. A major regional drainage, Cache Creek flows through this depression and has been offset ~6 km right-laterally by the GVF-BSF during the Quaternary. We recently discovered the Kuikui fault, a dextral-oblique slip fault within the stepover, using high-resolution imagery from LiDAR acquired by USGS in 2011 along major northern California fault zones (ARRA11_USGS, DOI: 10.5069/G9H70CRD, http://dx.doi.org/10.5069/G9H70CRD). The Kuikui fault is ~2-3 km in length and forms steep, well-preserved scarps up to ~2.5 m high. It has only subtle expression of dextral slip, so its ratio of dip slip to strike slip is uncertain. Any evidence of large paleoearthquakes in the Wilson Valley stepover might indicate rupture of either the GVF or the BSF or both together, and timing information could be used to correlate events with other paleoseismic sites on the fault system. Additionally, fault creep has been documented on both the Highway 20 and Hunting Creek fault sections, so that any fault offset on the Kuikui fault might also include some aseismic slip. Because wilderness regulations required manual excavation, several participants from USGS, HSU, other colleagues and volunteers together dug an 8-m long by ≤1 m deep trench by hand to expose faulting in thin layers of alluvium deposited across the Kuikui fault. The youngest, and currently active soil layer is vertically offset by a minimum of 7 cm on a single fault strand. A much broader fault zone suggests larger movement has occurred. This exposure did not allow us to discriminate whether slip occurred as creep or by dynamic rupture. Future additional exposures may

  5. Differential Fault Analysis of Rabbit

    NASA Astrophysics Data System (ADS)

    Kircanski, Aleksandar; Youssef, Amr M.

    Rabbit is a high speed scalable stream cipher with 128-bit key and a 64-bit initialization vector. It has passed all three stages of the ECRYPT stream cipher project and is a member of eSTREAM software portfolio. In this paper, we present a practical fault analysis attack on Rabbit. The fault model in which we analyze the cipher is the one in which the attacker is assumed to be able to fault a random bit of the internal state of the cipher but cannot control the exact location of injected faults. Our attack requires around 128 - 256 faults, precomputed table of size 241.6 bytes and recovers the complete internal state of Rabbit in about 238 steps.

  6. Frictional Heterogeneities Along Carbonate Faults

    NASA Astrophysics Data System (ADS)

    Collettini, C.; Carpenter, B. M.; Scuderi, M.; Tesei, T.

    2014-12-01

    The understanding of fault-slip behaviour in carbonates has an important societal impact as a) a significant number of earthquakes nucleate within or propagate through these rocks, and b) half of the known petroleum reserves occur within carbonate reservoirs, which likely contain faults that experience fluid pressure fluctuations. Field studies on carbonate-bearing faults that are exhumed analogues of currently active structures of the seismogenic crust, show that fault rock types are systematically controlled by the lithology of the faulted protolith: localization associated with cataclasis, thermal decomposition and plastic deformation commonly affect fault rocks in massive limestone, whereas distributed deformation, pressure-solution and frictional sliding along phyllosilicates are observed in marly rocks. In addition, hydraulic fractures, indicating cyclic fluid pressure build-ups during the fault activity, are widespread. Standard double direct friction experiments on fault rocks from massive limestones show high friction, velocity neutral/weakening behaviour and significant re-strengthening during hold periods, on the contrary, phyllosilicate-rich shear zones are characterized by low friction, significant velocity strengthening behavior and no healing. We are currently running friction experiments on large rock samples (20x20 cm) in order to reproduce and characterize the interaction of fault rock frictional heterogeneities observed in the field. In addition we have been performing experiments at near lithostatic fluid pressure in the double direct shear configuration within a pressure vessel to test the Rate and State friction stability under these conditions. Our combination of structural observations and mechanical data have been revealing the processes and structures that are at the base of the broad spectrum of fault slip behaviors recently documented by high-resolution geodetic and seismological data.

  7. The Lawanopo Fault, central Sulawesi, East Indonesia

    NASA Astrophysics Data System (ADS)

    Natawidjaja, Danny Hilman; Daryono, Mudrik R.

    2015-04-01

    The dominant tectonic-force factor in the Sulawesi Island is the westward Bangga-Sula microplate tectonic intrusion, driven by the 12 mm/year westward motion of the Pacific Plate relative to Eurasia. This tectonic intrusion are accommodated by a series of major left-lateral strike-slip fault zones including Sorong Fault, Sula-Sorong Fault, Matano Fault, Palukoro Fault, and Lawanopo Fault zones. The Lawanopo fault has been considered as an active left-lateral strike-slip fault. The natural exposures of the Lawanopo Fault are clear, marked by the breaks and liniemants of topography along the fault line, and also it serves as a tectonic boundary between the different rock assemblages. Inpections of IFSAR 5m-grid DEM and field checks show that the fault traces are visible by lineaments of topographical slope breaks, linear ridges and stream valleys, ridge neckings, and they are also associated with hydrothermal deposits and hot springs. These are characteristics of young fault, so their morphological expressions can be seen still. However, fault scarps and other morpho-tectonic features appear to have been diffused by erosions and young sediment depositions. No fresh fault scarps, stream deflections or offsets, or any influences of fault movements on recent landscapes are observed associated with fault traces. Hence, the faults do not show any evidence of recent activity. This is consistent with lack of seismicity on the fault.

  8. Faulting and Serpentinisation of Peridotites in the Leka Ophiolite

    NASA Astrophysics Data System (ADS)

    Dunkel, Kristina G.; Drivdal, Kerstin; Austrheim, Håkon; Andersen, Torgeir B.; Jamtveit, Bjørn

    2014-05-01

    The ocean floor is strongly affected by seismic activity along mid ocean ridges and transform faults, where the upper mantle may undergo extensive alteration and serpentinisation. While the spatial link between faulting and serpentinisation is generally accepted, the causal connection between these two processes is not well understood. The cumulate section of the Leka Ophiolite, north-central Norway, is transected by kilometre long sets of parallel faults and shear zones with a dextral shear. The discrete faults have spacings from centimetres to decimetres and displacements in the same range. They alternate with breccia zones and metre thick shear zones with displacements up to 30 m. The extent of the faulted areas and the consistent dextral displacements indicate a regional deformation process, possibly related to a transform. The observation of progressive peridotite alteration in the Leka Ophiolite gives new insights into the interplay between serpentinisation and deformation. In the least altered peridotite, propagating fractures produce a texture reminiscent of cleaved olivine. Serpentinisation initiates along the cleavage planes. In more deformed samples, the centres of the discrete faults contain relatively large coherent olivine fragments alternating with trails of small spinel grains parallel to the fault. Most of the spinel is ferrichromite or magnetite, but some contain cores of primary chromite. Towards the margins of the faults, the amount of (fibrous) serpentine and fracturing of olivine increases significantly. The fault margins appear dark in hand specimens, which is due to finely dispersed magnetite grains in olivine and serpentine. The surrounding damage zones contain moderately serpentinised olivine grains exhibiting different deformation indicators such as undulous extinction, deformation lamellae and subgrain boundaries. In the breccia zones, where peridotite clasts are enclosed by deformation zones with the same buildup as the faults, this

  9. Anisotropy of Resisitiviy Distributions and Fault Rock Microstructures in Fault Zones -Two Case Studies of Hatagawa and Atotsugawa Fault, Japan-

    NASA Astrophysics Data System (ADS)

    Omura, K.

    2015-12-01

    Structure and physical characteristics in a fault zone are not homogeneous. The inhomogeneity should be related to earthquake generation mechanism. However, main features of the inhomogeneity in fault zones are not yet sufficiently understood. It is considered to be effective to compare geophysical data of geophysical survey and/or downhole logging with physical properties, microstructures and mineral compositions of fault rocks in the fault zone. In this presentation, results of the comparisons are introduced in the case of two fault zones; Hatagawa and Atotsugawa fault, in north-east and central Japan, respectively, and factors affecting the inhomogeneity of fault structure are suggested.Anisotropic resistivity measurements in laboratory were compared with microscopic observations of fault rocks recovered from outcrops of Hatagawa fault. In the case of Atotsugawa fault, the anisotropic resistivity profiles by physical survey across the fault zones were compared with microscopic observations and mineral composition analysis of fault rocks provided by drilling into the fault zone. As a result, the anisotropic resistivity profiles are strongly related to foliation structure of fault rocks. It is suggested that fault slip at the earthquake and shear deformation during the earthquake recurrence time develope foliation fabrics of fault rocks, and that the resistivity profile becomes anisotropic progressively in the fault zone.

  10. Fault Tolerant State Machines

    NASA Technical Reports Server (NTRS)

    Burke, Gary R.; Taft, Stephanie

    2004-01-01

    State machines are commonly used to control sequential logic in FPGAs and ASKS. An errant state machine can cause considerable damage to the device it is controlling. For example in space applications, the FPGA might be controlling Pyros, which when fired at the wrong time will cause a mission failure. Even a well designed state machine can be subject to random errors us a result of SEUs from the radiation environment in space. There are various ways to encode the states of a state machine, and the type of encoding makes a large difference in the susceptibility of the state machine to radiation. In this paper we compare 4 methods of state machine encoding and find which method gives the best fault tolerance, as well as determining the resources needed for each method.

  11. Faulted Sedimentary Rocks

    NASA Technical Reports Server (NTRS)

    2004-01-01

    27 June 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some of the layered, sedimentary rock outcrops that occur in a crater located at 8oN, 7oW, in western Arabia Terra. Dark layers and dark sand have enhanced the contrast of this scene. In the upper half of the image, one can see numerous lines that off-set the layers. These lines are faults along which the rocks have broken and moved. The regularity of layer thickness and erosional expression are taken as evidence that the crater in which these rocks occur might once have been a lake. The image covers an area about 1.9 km (1.2 mi) wide. Sunlight illuminates the scene from the lower left.

  12. Comparison of Cenozoic Faulting at the Savannah River Site to Fault Characteristics of the Atlantic Coast Fault Province: Implications for Fault Capability

    SciTech Connect

    Cumbest, R.J.

    2000-11-14

    This study compares the faulting observed on the Savannah River Site and vicinity with the faults of the Atlantic Coastal Fault Province and concludes that both sets of faults exhibit the same general characteristics and are closely associated. Based on the strength of this association it is concluded that the faults observed on the Savannah River Site and vicinity are in fact part of the Atlantic Coastal Fault Province. Inclusion in this group means that the historical precedent established by decades of previous studies on the seismic hazard potential for the Atlantic Coastal Fault Province is relevant to faulting at the Savannah River Site. That is, since these faults are genetically related the conclusion of ''not capable'' reached in past evaluations applies.In addition, this study establishes a set of criteria by which individual faults may be evaluated in order to assess their inclusion in the Atlantic Coast Fault Province and the related association of the ''not capable'' conclusion.

  13. Improving Multiple Fault Diagnosability using Possible Conflicts

    NASA Technical Reports Server (NTRS)

    Daigle, Matthew J.; Bregon, Anibal; Biswas, Gautam; Koutsoukos, Xenofon; Pulido, Belarmino

    2012-01-01

    Multiple fault diagnosis is a difficult problem for dynamic systems. Due to fault masking, compensation, and relative time of fault occurrence, multiple faults can manifest in many different ways as observable fault signature sequences. This decreases diagnosability of multiple faults, and therefore leads to a loss in effectiveness of the fault isolation step. We develop a qualitative, event-based, multiple fault isolation framework, and derive several notions of multiple fault diagnosability. We show that using Possible Conflicts, a model decomposition technique that decouples faults from residuals, we can significantly improve the diagnosability of multiple faults compared to an approach using a single global model. We demonstrate these concepts and provide results using a multi-tank system as a case study.

  14. Subaru FATS (fault tracking system)

    NASA Astrophysics Data System (ADS)

    Winegar, Tom W.; Noumaru, Junichi

    2000-07-01

    The Subaru Telescope requires a fault tracking system to record the problems and questions that staff experience during their work, and the solutions provided by technical experts to these problems and questions. The system records each fault and routes it to a pre-selected 'solution-provider' for each type of fault. The solution provider analyzes the fault and writes a solution that is routed back to the fault reporter and recorded in a 'knowledge-base' for future reference. The specifications of our fault tracking system were unique. (1) Dual language capacity -- Our staff speak both English and Japanese. Our contractors speak Japanese. (2) Heterogeneous computers -- Our computer workstations are a mixture of SPARCstations, Macintosh and Windows computers. (3) Integration with prime contractors -- Mitsubishi and Fujitsu are primary contractors in the construction of the telescope. In many cases, our 'experts' are our contractors. (4) Operator scheduling -- Our operators spend 50% of their work-month operating the telescope, the other 50% is spent working day shift at the base facility in Hilo, or day shift at the summit. We plan for 8 operators, with a frequent rotation. We need to keep all operators informed on the current status of all faults, no matter the operator's location.

  15. Weak Fault Feature Extraction of Rolling Bearings Based on an Improved Kurtogram

    PubMed Central

    Chen, Xianglong; Feng, Fuzhou; Zhang, Bingzhi

    2016-01-01

    Kurtograms have been verified to be an efficient tool in bearing fault detection and diagnosis because of their superiority in extracting transient features. However, the short-time Fourier Transform is insufficient in time-frequency analysis and kurtosis is deficient in detecting cyclic transients. Those factors weaken the performance of the original kurtogram in extracting weak fault features. Correlated Kurtosis (CK) is then designed, as a more effective solution, in detecting cyclic transients. Redundant Second Generation Wavelet Packet Transform (RSGWPT) is deemed to be effective in capturing more detailed local time-frequency description of the signal, and restricting the frequency aliasing components of the analysis results. The authors in this manuscript, combining the CK with the RSGWPT, propose an improved kurtogram to extract weak fault features from bearing vibration signals. The analysis of simulation signals and real application cases demonstrate that the proposed method is relatively more accurate and effective in extracting weak fault features. PMID:27649171

  16. A Feature Extraction Method for Fault Classification of Rolling Bearing based on PCA

    NASA Astrophysics Data System (ADS)

    Wang, Fengtao; Sun, Jian; Yan, Dawen; Zhang, Shenghua; Cui, Liming; Xu, Yong

    2015-07-01

    This paper discusses the fault feature selection using principal component analysis (PCA) for bearing faults classification. Multiple features selected from the time-frequency domain parameters of vibration signals are analyzed. First, calculate the time domain statistical features, such as root mean square and kurtosis; meanwhile, by Fourier transformation and Hilbert transformation, the frequency statistical features are extracted from the frequency spectrum. Then the PCA is used to reduce the dimension of feature vectors drawn from raw vibration signals, which can improve real time performance and accuracy of the fault diagnosis. Finally, a fuzzy C-means (FCM) model is established to implement the diagnosis of rolling bearing faults. Practical rolling bearing experiment data is used to verify the effectiveness of the proposed method.

  17. Weak Fault Feature Extraction of Rolling Bearings Based on an Improved Kurtogram.

    PubMed

    Chen, Xianglong; Feng, Fuzhou; Zhang, Bingzhi

    2016-01-01

    Kurtograms have been verified to be an efficient tool in bearing fault detection and diagnosis because of their superiority in extracting transient features. However, the short-time Fourier Transform is insufficient in time-frequency analysis and kurtosis is deficient in detecting cyclic transients. Those factors weaken the performance of the original kurtogram in extracting weak fault features. Correlated Kurtosis (CK) is then designed, as a more effective solution, in detecting cyclic transients. Redundant Second Generation Wavelet Packet Transform (RSGWPT) is deemed to be effective in capturing more detailed local time-frequency description of the signal, and restricting the frequency aliasing components of the analysis results. The authors in this manuscript, combining the CK with the RSGWPT, propose an improved kurtogram to extract weak fault features from bearing vibration signals. The analysis of simulation signals and real application cases demonstrate that the proposed method is relatively more accurate and effective in extracting weak fault features. PMID:27649171

  18. Weak Fault Feature Extraction of Rolling Bearings Based on an Improved Kurtogram.

    PubMed

    Chen, Xianglong; Feng, Fuzhou; Zhang, Bingzhi

    2016-09-13

    Kurtograms have been verified to be an efficient tool in bearing fault detection and diagnosis because of their superiority in extracting transient features. However, the short-time Fourier Transform is insufficient in time-frequency analysis and kurtosis is deficient in detecting cyclic transients. Those factors weaken the performance of the original kurtogram in extracting weak fault features. Correlated Kurtosis (CK) is then designed, as a more effective solution, in detecting cyclic transients. Redundant Second Generation Wavelet Packet Transform (RSGWPT) is deemed to be effective in capturing more detailed local time-frequency description of the signal, and restricting the frequency aliasing components of the analysis results. The authors in this manuscript, combining the CK with the RSGWPT, propose an improved kurtogram to extract weak fault features from bearing vibration signals. The analysis of simulation signals and real application cases demonstrate that the proposed method is relatively more accurate and effective in extracting weak fault features.

  19. Finding faults with the data

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    Rudolph Giuliani and Hillary Rodham Clinton are crisscrossing upstate New York looking for votes in the U.S. Senate race. Also cutting back and forth across upstate New York are hundreds of faults of a kind characterized by very sporadic seismic activity according to Robert Jacobi, professor of geology at the University of Buffalo (UB), who conducted research with fellow UB geology professor John Fountain."We have proof that upstate New York is crisscrossed by faults," Jacobi said. "In the past, the Appalachian Plateau—which stretches from Albany to Buffalo—was considered a pretty boring place structurally without many faults or folds of any significance."

  20. Enhanced detection of rolling element bearing fault based on stochastic resonance

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaofei; Hu, Niaoqing; Cheng, Zhe; Hu, Lei

    2012-11-01

    Early bearing faults can generate a series of weak impacts. All the influence factors in measurement may degrade the vibration signal. Currently, bearing fault enhanced detection method based on stochastic resonance(SR) is implemented by expensive computation and demands high sampling rate, which requires high quality software and hardware for fault diagnosis. In order to extract bearing characteristic frequencies component, SR normalized scale transform procedures are presented and a circuit module is designed based on parameter-tuning bistable SR. In the simulation test, discrete and analog sinusoidal signals under heavy noise are enhanced by SR normalized scale transform and circuit module respectively. Two bearing fault enhanced detection strategies are proposed. One is realized by pure computation with normalized scale transform for sampled vibration signal, and the other is carried out by designed SR hardware with circuit module for analog vibration signal directly. The first strategy is flexible for discrete signal processing, and the second strategy demands much lower sampling frequency and less computational cost. The application results of the two strategies on bearing inner race fault detection of a test rig show that the local signal to noise ratio of the characteristic components obtained by the proposed methods are enhanced by about 50% compared with the band pass envelope analysis for the bearing with weaker fault. In addition, helicopter transmission bearing fault detection validates the effectiveness of the enhanced detection strategy with hardware. The combination of SR normalized scale transform and circuit module can meet the need of different application fields or conditions, thus providing a practical scheme for enhanced detection of bearing fault.

  1. The Guayape fault system, Honduras, Central America

    NASA Astrophysics Data System (ADS)

    Finch, R. C.; Ritchie, A. W.

    The Guayape fault system (GFS) is the longest continuous structural feature in Honduras and a major tectonic element within the Chortis block of the Caribbean Plate. Nevertheless, it has been largely ignored in most tectonic studies of this region, apparently due to lack of detailed information concerning the location, extent, and nature of the system. This paper attempts to fill this gap. The GFS is defined as a complex band of faults, from 2 to 25 km in width, which trends N30°-35°E for 290 km from the Honduras-Nicaragua border near El Paraíso to the Caribbean coast near the mouth of the Río Sico. A probable offshore continuation can be seen in seismic reflection profiles. Field mapping and aerial photograph interpretation indicate that the GFS proper terminates in a series of splay and cross faults in the Jamastrán Valley-El Paraíso area and does not make an en echelon transfer to connect with the Choluteca lineament to the southwest. The most obvious manifestation of the GFS is the fault-controlled alignment of major segments of the Guayambre, Guayape, Tinto, Paulaya, and Sico Rivers. The great length and rectilinearity of the GFS indicate that it is a strike-slip fault, which is confirmed by abundant horizontal and sub-horizontal slickensides, vertical drag-folds, shutterridges, and extensional basins generated by strike-slip displacement. Subsidiary dip-slip faults, expected in a major transcurrent fault system, are common, especially where extensional basins have developed. Stream offsets of about 50 km, some mesoscopic slip indicators, the regional distribution of a shaly member of the Honduras Group, and regional tectonic considerations suggest sinistral displacement on the GFS. On the other hand, three, possibly four, modern topographic depressions along the GFS are dextral strike-slip extensional basins, and dextral mesoscopic slip indicators outnumber sinistral indicators. A two-stage slip history is thereby inferred, with a sinistral-slip phase

  2. Fault-free performance validation of fault-tolerant multiprocessors

    NASA Technical Reports Server (NTRS)

    Czeck, Edward W.; Feather, Frank E.; Grizzaffi, Ann Marie; Segall, Zary Z.; Siewiorek, Daniel P.

    1987-01-01

    A validation methodology for testing the performance of fault-tolerant computer systems was developed and applied to the Fault-Tolerant Multiprocessor (FTMP) at NASA-Langley's AIRLAB facility. This methodology was claimed to be general enough to apply to any ultrareliable computer system. The goal of this research was to extend the validation methodology and to demonstrate the robustness of the validation methodology by its more extensive application to NASA's Fault-Tolerant Multiprocessor System (FTMP) and to the Software Implemented Fault-Tolerance (SIFT) Computer System. Furthermore, the performance of these two multiprocessors was compared by conducting similar experiments. An analysis of the results shows high level language instruction execution times for both SIFT and FTMP were consistent and predictable, with SIFT having greater throughput. At the operating system level, FTMP consumes 60% of the throughput for its real-time dispatcher and 5% on fault-handling tasks. In contrast, SIFT consumes 16% of its throughput for the dispatcher, but consumes 66% in fault-handling software overhead.

  3. Contrasting frictional behaviour of fault gouges containing Mg-rich phyllosilicates

    NASA Astrophysics Data System (ADS)

    Sanchez Roa, C.; Faulkner, D.; Jimenez Millan, J.; Nieto, F.

    2015-12-01

    The clay mineralogy of fault gouges has important implications on frictional properties and stability of fault planes. We studied the specific case of the Galera fault zone where fault gouges containing Mg-rich phyllosilicates appear as hydrothermal deposits related to high salinity fluids enriched in Mg2+. These deposits are dominated by sepiolite and palygorskite, both fibrous clay minerals with similar composition to Mg-smectite. The frictional strengths of sepiolite and palygorskite have not yet been determined, however, as they are part of the clay mineral group, it has been assumed that their frictional behaviour would be in line with platy clay minerals. We performed frictional sliding experiments on powdered pure standards and fault rocks in order to establish the frictional behaviour of sepiolite and palygorskite using a triaxial deformation apparatus with a servo-controlled axial loading system and fluid pressure pump. Friction coefficients for palygorskite and sepiolite as monomineralic samples were found to be 0.65 to 0.7 for dry experiments, and 0.45 to 0.5 for water-saturated experiments. Although these fibrous minerals are part of the phyllosilicates group, they show higher friction coefficients and their mechanical behaviour is less stable than platy clay minerals. This difference is a consequence of their stronger structural framework and the discontinuity of water layers. Our results present a contrast in mechanical behaviour between Mg-rich fibrous and platy clay minerals in fault gouges, where smectite is known to considerably reduce friction coefficients and to increase the stability of the fault plane leading to creeping processes. Transformations between saponite and sepiolite have been previously observed and could modify the deformation regime of a fault zone. Constraining the stability conditions and possible mineral reactions or transformations in fault gouges could help us understand the general role of clay minerals in fault stability.

  4. Ductilizing Bulk Metallic Glass Composite by Tailoring Stacking Fault Energy

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Zhou, D. Q.; Song, W. L.; Wang, H.; Zhang, Z. Y.; Ma, D.; Wang, X. L.; Lu, Z. P.

    2012-12-01

    Martensitic transformation was successfully introduced to bulk metallic glasses as the reinforcement micromechanism. In this Letter, it was found that the twinning property of the reinforcing crystals can be dramatically improved by reducing the stacking fault energy through microalloying, which effectively alters the electron charge density redistribution on the slipping plane. The enhanced twinning propensity promotes the martensitic transformation of the reinforcing austenite and, consequently, improves plastic stability and the macroscopic tensile ductility. In addition, a general rule to identify effective microalloying elements based on their electronegativity and atomic size was proposed.

  5. Expert System Detects Power-Distribution Faults

    NASA Technical Reports Server (NTRS)

    Walters, Jerry L.; Quinn, Todd M.

    1994-01-01

    Autonomous Power Expert (APEX) computer program is prototype expert-system program detecting faults in electrical-power-distribution system. Assists human operators in diagnosing faults and deciding what adjustments or repairs needed for immediate recovery from faults or for maintenance to correct initially nonthreatening conditions that could develop into faults. Written in Lisp.

  6. 20 CFR 410.561b - Fault.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 2 2011-04-01 2011-04-01 false Fault. 410.561b Section 410.561b Employees' Benefits SOCIAL SECURITY ADMINISTRATION FEDERAL COAL MINE HEALTH AND SAFETY ACT OF 1969, TITLE IV-BLACK LUNG BENEFITS (1969- ) Payment of Benefits § 410.561b Fault. Fault as used in without fault (see §...

  7. 20 CFR 410.561b - Fault.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false Fault. 410.561b Section 410.561b Employees' Benefits SOCIAL SECURITY ADMINISTRATION FEDERAL COAL MINE HEALTH AND SAFETY ACT OF 1969, TITLE IV-BLACK LUNG BENEFITS (1969- ) Payment of Benefits § 410.561b Fault. Fault as used in without fault (see §...

  8. 22 CFR 17.3 - Fault.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 22 Foreign Relations 1 2011-04-01 2011-04-01 false Fault. 17.3 Section 17.3 Foreign Relations...) § 17.3 Fault. A recipient of an overpayment is without fault if he or she performed no act of... agency may have been at fault in initiating an overpayment will not necessarily relieve the...

  9. 22 CFR 17.3 - Fault.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 22 Foreign Relations 1 2014-04-01 2014-04-01 false Fault. 17.3 Section 17.3 Foreign Relations...) § 17.3 Fault. A recipient of an overpayment is without fault if he or she performed no act of... agency may have been at fault in initiating an overpayment will not necessarily relieve the...

  10. 22 CFR 17.3 - Fault.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Fault. 17.3 Section 17.3 Foreign Relations...) § 17.3 Fault. A recipient of an overpayment is without fault if he or she performed no act of... agency may have been at fault in initiating an overpayment will not necessarily relieve the...

  11. 22 CFR 17.3 - Fault.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 22 Foreign Relations 1 2012-04-01 2012-04-01 false Fault. 17.3 Section 17.3 Foreign Relations...) § 17.3 Fault. A recipient of an overpayment is without fault if he or she performed no act of... agency may have been at fault in initiating an overpayment will not necessarily relieve the...

  12. 22 CFR 17.3 - Fault.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 22 Foreign Relations 1 2013-04-01 2013-04-01 false Fault. 17.3 Section 17.3 Foreign Relations...) § 17.3 Fault. A recipient of an overpayment is without fault if he or she performed no act of... agency may have been at fault in initiating an overpayment will not necessarily relieve the...

  13. The fault-tree compiler

    NASA Technical Reports Server (NTRS)

    Martensen, Anna L.; Butler, Ricky W.

    1987-01-01

    The Fault Tree Compiler Program is a new reliability tool used to predict the top event probability for a fault tree. Five different gate types are allowed in the fault tree: AND, OR, EXCLUSIVE OR, INVERT, and M OF N gates. The high level input language is easy to understand and use when describing the system tree. In addition, the use of the hierarchical fault tree capability can simplify the tree description and decrease program execution time. The current solution technique provides an answer precise (within the limits of double precision floating point arithmetic) to the five digits in the answer. The user may vary one failure rate or failure probability over a range of values and plot the results for sensitivity analyses. The solution technique is implemented in FORTRAN; the remaining program code is implemented in Pascal. The program is written to run on a Digital Corporation VAX with the VMS operation system.

  14. Cell boundary fault detection system

    DOEpatents

    Archer, Charles Jens; Pinnow, Kurt Walter; Ratterman, Joseph D.; Smith, Brian Edward

    2009-05-05

    A method determines a nodal fault along the boundary, or face, of a computing cell. Nodes on adjacent cell boundaries communicate with each other, and the communications are analyzed to determine if a node or connection is faulty.

  15. Reading Transformation

    ERIC Educational Resources Information Center

    Reeves, Melinda

    2006-01-01

    The parents of students who attend Decatur High School thought that there was little hope of their kids going on to college. After a year or so in Decatur's reading program, their sons and daughters were both transformed and college bound. In this article, the author describes how Decatur was able to successfully transform their students. Seven…

  16. Transformational Events

    ERIC Educational Resources Information Center

    Denning, Peter J.; Hiles, John E.

    2006-01-01

    Transformational Events is a new pedagogic pattern that explains how innovations (and other transformations) happened. The pattern is three temporal stages: an interval of increasingly unsatisfactory ad hoc solutions to a persistent problem (the "mess"), an offer of an invention or of a new way of thinking, and a period of widespread adoption and…

  17. Afterslip, tremor, and the Denali fault earthquake

    USGS Publications Warehouse

    Gomberg, Joan; Prejean, Stephanie; Ruppert, Natalia

    2012-01-01

    We tested the hypothesis that afterslip should be accompanied by tremor using observations of seismic and aseismic deformation surrounding the 2002 M 7.9 Denali fault, Alaska, earthquake (DFE). Afterslip happens more frequently than spontaneous slow slip and has been observed in a wider range of tectonic environments, and thus the existence or absence of tremor accompanying afterslip may provide new clues about tremor generation. We also searched for precursory tremor, as a proxy for posited accelerating slip leading to rupture. Our search yielded no tremor during the five days prior to the DFE or in several intervals in the three months after. This negative result and an array of other observations all may be explained by rupture penetrating below the presumed locked zone into the frictional transition zone. While not unique, such an explanation corroborates previous models of megathrust and transform earthquake ruptures that extend well into the transition zone.

  18. Fault Tree Analysis: A Bibliography

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Fault tree analysis is a top-down approach to the identification of process hazards. It is as one of the best methods for systematically identifying an graphically displaying the many ways some things can go wrong. This bibliography references 266 documents in the NASA STI Database that contain the major concepts. fault tree analysis, risk an probability theory, in the basic index or major subject terms. An abstract is included with most citations, followed by the applicable subject terms.

  19. Hardware Fault Simulator for Microprocessors

    NASA Technical Reports Server (NTRS)

    Hess, L. M.; Timoc, C. C.

    1983-01-01

    Breadboarded circuit is faster and more thorough than software simulator. Elementary fault simulator for AND gate uses three gates and shaft register to simulate stuck-at-one or stuck-at-zero conditions at inputs and output. Experimental results showed hardware fault simulator for microprocessor gave faster results than software simulator, by two orders of magnitude, with one test being applied every 4 microseconds.

  20. Fault-tolerant rotary actuator

    DOEpatents

    Tesar, Delbert

    2006-10-17

    A fault-tolerant actuator module, in a single containment shell, containing two actuator subsystems that are either asymmetrically or symmetrically laid out is provided. Fault tolerance in the actuators of the present invention is achieved by the employment of dual sets of equal resources. Dual resources are integrated into single modules, with each having the external appearance and functionality of a single set of resources.

  1. Normal fault earthquakes or graviquakes.

    PubMed

    Doglioni, C; Carminati, E; Petricca, P; Riguzzi, F

    2015-07-14

    Earthquakes are dissipation of energy throughout elastic waves. Canonically is the elastic energy accumulated during the interseismic period. However, in crustal extensional settings, gravity is the main energy source for hangingwall fault collapsing. Gravitational potential is about 100 times larger than the observed magnitude, far more than enough to explain the earthquake. Therefore, normal faults have a different mechanism of energy accumulation and dissipation (graviquakes) with respect to other tectonic settings (strike-slip and contractional), where elastic energy allows motion even against gravity. The bigger the involved volume, the larger is their magnitude. The steeper the normal fault, the larger is the vertical displacement and the larger is the seismic energy released. Normal faults activate preferentially at about 60° but they can be shallower in low friction rocks. In low static friction rocks, the fault may partly creep dissipating gravitational energy without releasing great amount of seismic energy. The maximum volume involved by graviquakes is smaller than the other tectonic settings, being the activated fault at most about three times the hypocentre depth, explaining their higher b-value and the lower magnitude of the largest recorded events. Having different phenomenology, graviquakes show peculiar precursors.

  2. Normal fault earthquakes or graviquakes.

    PubMed

    Doglioni, C; Carminati, E; Petricca, P; Riguzzi, F

    2015-01-01

    Earthquakes are dissipation of energy throughout elastic waves. Canonically is the elastic energy accumulated during the interseismic period. However, in crustal extensional settings, gravity is the main energy source for hangingwall fault collapsing. Gravitational potential is about 100 times larger than the observed magnitude, far more than enough to explain the earthquake. Therefore, normal faults have a different mechanism of energy accumulation and dissipation (graviquakes) with respect to other tectonic settings (strike-slip and contractional), where elastic energy allows motion even against gravity. The bigger the involved volume, the larger is their magnitude. The steeper the normal fault, the larger is the vertical displacement and the larger is the seismic energy released. Normal faults activate preferentially at about 60° but they can be shallower in low friction rocks. In low static friction rocks, the fault may partly creep dissipating gravitational energy without releasing great amount of seismic energy. The maximum volume involved by graviquakes is smaller than the other tectonic settings, being the activated fault at most about three times the hypocentre depth, explaining their higher b-value and the lower magnitude of the largest recorded events. Having different phenomenology, graviquakes show peculiar precursors. PMID:26169163

  3. Software Fault Tolerance: A Tutorial

    NASA Technical Reports Server (NTRS)

    Torres-Pomales, Wilfredo

    2000-01-01

    Because of our present inability to produce error-free software, software fault tolerance is and will continue to be an important consideration in software systems. The root cause of software design errors is the complexity of the systems. Compounding the problems in building correct software is the difficulty in assessing the correctness of software for highly complex systems. After a brief overview of the software development processes, we note how hard-to-detect design faults are likely to be introduced during development and how software faults tend to be state-dependent and activated by particular input sequences. Although component reliability is an important quality measure for system level analysis, software reliability is hard to characterize and the use of post-verification reliability estimates remains a controversial issue. For some applications software safety is more important than reliability, and fault tolerance techniques used in those applications are aimed at preventing catastrophes. Single version software fault tolerance techniques discussed include system structuring and closure, atomic actions, inline fault detection, exception handling, and others. Multiversion techniques are based on the assumption that software built differently should fail differently and thus, if one of the redundant versions fails, it is expected that at least one of the other versions will provide an acceptable output. Recovery blocks, N-version programming, and other multiversion techniques are reviewed.

  4. Normal fault earthquakes or graviquakes

    PubMed Central

    Doglioni, C.; Carminati, E.; Petricca, P.; Riguzzi, F.

    2015-01-01

    Earthquakes are dissipation of energy throughout elastic waves. Canonically is the elastic energy accumulated during the interseismic period. However, in crustal extensional settings, gravity is the main energy source for hangingwall fault collapsing. Gravitational potential is about 100 times larger than the observed magnitude, far more than enough to explain the earthquake. Therefore, normal faults have a different mechanism of energy accumulation and dissipation (graviquakes) with respect to other tectonic settings (strike-slip and contractional), where elastic energy allows motion even against gravity. The bigger the involved volume, the larger is their magnitude. The steeper the normal fault, the larger is the vertical displacement and the larger is the seismic energy released. Normal faults activate preferentially at about 60° but they can be shallower in low friction rocks. In low static friction rocks, the fault may partly creep dissipating gravitational energy without releasing great amount of seismic energy. The maximum volume involved by graviquakes is smaller than the other tectonic settings, being the activated fault at most about three times the hypocentre depth, explaining their higher b-value and the lower magnitude of the largest recorded events. Having different phenomenology, graviquakes show peculiar precursors. PMID:26169163

  5. Passive fault current limiting device

    DOEpatents

    Evans, D.J.; Cha, Y.S.

    1999-04-06

    A passive current limiting device and isolator is particularly adapted for use at high power levels for limiting excessive currents in a circuit in a fault condition such as an electrical short. The current limiting device comprises a magnetic core wound with two magnetically opposed, parallel connected coils of copper, a high temperature superconductor or other electrically conducting material, and a fault element connected in series with one of the coils. Under normal operating conditions, the magnetic flux density produced by the two coils cancel each other. Under a fault condition, the fault element is triggered to cause an imbalance in the magnetic flux density between the two coils which results in an increase in the impedance in the coils. While the fault element may be a separate current limiter, switch, fuse, bimetal strip or the like, it preferably is a superconductor current limiter conducting one-half of the current load compared to the same limiter wired to carry the total current of the circuit. The major voltage during a fault condition is in the coils wound on the common core in a preferred embodiment. 6 figs.

  6. Passive fault current limiting device

    DOEpatents

    Evans, Daniel J.; Cha, Yung S.

    1999-01-01

    A passive current limiting device and isolator is particularly adapted for use at high power levels for limiting excessive currents in a circuit in a fault condition such as an electrical short. The current limiting device comprises a magnetic core wound with two magnetically opposed, parallel connected coils of copper, a high temperature superconductor or other electrically conducting material, and a fault element connected in series with one of the coils. Under normal operating conditions, the magnetic flux density produced by the two coils cancel each other. Under a fault condition, the fault element is triggered to cause an imbalance in the magnetic flux density between the two coils which results in an increase in the impedance in the coils. While the fault element may be a separate current limiter, switch, fuse, bimetal strip or the like, it preferably is a superconductor current limiter conducting one-half of the current load compared to the same limiter wired to carry the total current of the circuit. The major voltage during a fault condition is in the coils wound on the common core in a preferred embodiment.

  7. Recent geodynamics of dangerous faults

    NASA Astrophysics Data System (ADS)

    Kuzmin, Yu. O.

    2016-09-01

    The analysis of the existing information concerning the present-day deformation activity of the fault zones in seismically active and aseismic regions suggests that the notions of an active fault and a dangerous fault should be distinguished. It is shown that a fault which is active for an expert in geotectonics will not be considered dangerous by an expert in geotechnical monitoring of buildings. The definition is given according to which a dangerous fault is understood as a zone of linear destruction which accommodates the contemporary short-period (a few months and years) pulsed and/or alternating motions with strain rates above 5 × 10-5 per annum and earthquakes with M ≥ 5. A technique is developed for identifying the dangerous faults based on monitoring the recent ground surface displacements in accordance with a special protocol which ensures an increased degree of detail in time and space. Based on the idea of the probable accumulation of dangerous strains during the operating cycle of the objects, the criteria for assessing their geodynamical risks are formulated.

  8. Aeromagnetic anomalies over faulted strata

    USGS Publications Warehouse

    Grauch, V.J.S.; Hudson, Mark R.

    2011-01-01

    High-resolution aeromagnetic surveys are now an industry standard and they commonly detect anomalies that are attributed to faults within sedimentary basins. However, detailed studies identifying geologic sources of magnetic anomalies in sedimentary environments are rare in the literature. Opportunities to study these sources have come from well-exposed sedimentary basins of the Rio Grande rift in New Mexico and Colorado. High-resolution aeromagnetic data from these areas reveal numerous, curvilinear, low-amplitude (2–15 nT at 100-m terrain clearance) anomalies that consistently correspond to intrasedimentary normal faults (Figure 1). Detailed geophysical and rock-property studies provide evidence for the magnetic sources at several exposures of these faults in the central Rio Grande rift (summarized in Grauch and Hudson, 2007, and Hudson et al., 2008). A key result is that the aeromagnetic anomalies arise from the juxtaposition of magnetically differing strata at the faults as opposed to chemical processes acting at the fault zone. The studies also provide (1) guidelines for understanding and estimating the geophysical parameters controlling aeromagnetic anomalies at faulted strata (Grauch and Hudson), and (2) observations on key geologic factors that are favorable for developing similar sedimentary sources of aeromagnetic anomalies elsewhere (Hudson et al.).

  9. Splay fault surface rupture triggered by the 2010 Chile earthquake

    NASA Astrophysics Data System (ADS)

    Melnick, D.; Moreno, M.; Motagh, M.; Cisternas, M.

    2010-12-01

    and a northward tilt revealed by ALOS InSAR data, biomarkers, campaign GPS, and leveling of a benchmark. This pattern of tilting mimics that of emerged late Holocene beach ridges, and is rather associated to motion along the Arauco Bay fault. Both systems may have been triggered by the megathrust event. Alternatively, it could arise at the sharp edge of a patch of high megathrust slip. Prominent rush of fluids from the rupture started during the Maule earthquake and continued for weeks. A small lake adjacent to the rupture, dry during summer droughts, became filled by the offspring. The flat morphology leads to small drainage basins with barely sufficient water to supply inhabitants during dry summer months suggesting that fluids rose through the fault from deeper levels in the crust. The SMFS is associated to the position of a paleo backstop structure, which limited an older deformable domain from the stable continental framework. The SMFS branches upward near the updip limit of the seismogenic zone, where fluids are expelled from mineral transformations. The Maule earthquake may have released trapped fluids at depth, which migrated through the splay fault reducing its friction and facilitating fault slip and surface rupture.

  10. Newport-Inglewood-Carlsbad-Coronado Bank Fault System Nearshore Southern California: Testing models for Quaternary deformation

    NASA Astrophysics Data System (ADS)

    Bennett, J. T.; Sorlien, C. C.; Cormier, M.; Bauer, R. L.

    2011-12-01

    The San Andreas fault system is distributed across hundreds of kilometers in southern California. This transform system includes offshore faults along the shelf, slope and basin- comprising part of the Inner California Continental Borderland. Previously, offshore faults have been interpreted as being discontinuous and striking parallel to the coast between Long Beach and San Diego. Our recent work, based on several thousand kilometers of deep-penetration industry multi-channel seismic reflection data (MCS) as well as high resolution U.S. Geological Survey MCS, indicates that many of the offshore faults are more geometrically continuous than previously reported. Stratigraphic interpretations of MCS profiles included the ca. 1.8 Ma Top Lower Pico, which was correlated from wells located offshore Long Beach (Sorlien et. al. 2010). Based on this age constraint, four younger (Late) Quaternary unconformities are interpreted through the slope and basin. The right-lateral Newport-Inglewood fault continues offshore near Newport Beach. We map a single fault for 25 kilometers that continues to the southeast along the base of the slope. There, the Newport-Inglewood fault splits into the San Mateo-Carlsbad fault, which is mapped for 55 kilometers along the base of the slope to a sharp bend. This bend is the northern end of a right step-over of 10 kilometers to the Descanso fault and about 17 km to the Coronado Bank fault. We map these faults for 50 kilometers as they continue over the Mexican border. Both the San Mateo - Carlsbad with the Newport-Inglewood fault and the Coronado Bank with the Descanso fault are paired faults that form flower structures (positive and negative, respectively) in cross section. Preliminary kinematic models indicate ~1km of right-lateral slip since ~1.8 Ma at the north end of the step-over. We are modeling the slip on the southern segment to test our hypothesis for a kinematically continuous right-lateral fault system. We are correlating four

  11. Transform continental margins - part 1: Concepts and models

    NASA Astrophysics Data System (ADS)

    Basile, Christophe

    2015-10-01

    This paper reviews the geodynamic concepts and models related to transform continental margins, and their implications on the structure of these margins. Simple kinematic models of transform faulting associated with continental rifting and oceanic accretion allow to define three successive stages of evolution, including intra-continental transform faulting, active transform margin, and passive transform margin. Each part of the transform margin experiences these three stages, but the evolution is diachronous along the margin. Both the duration of each stage and the cumulated strike-slip deformation increase from one extremity of the margin (inner corner) to the other (outer corner). Initiation of transform faulting is related to the obliquity between the trend of the lithospheric deformed zone and the relative displacement of the lithospheric plates involved in divergence. In this oblique setting, alternating transform and divergent plate boundaries correspond to spatial partitioning of the deformation. Both obliquity and the timing of partitioning influence the shape of transform margins. Oblique margin can be defined when oblique rifting is followed by oblique oceanic accretion. In this case, no transform margin should exist in the prolongation of the oceanic fracture zones. Vertical displacements along transform margins were mainly studied to explain the formation of marginal ridges. Numerous models were proposed, one of the most used is being based on thermal exchanges between the oceanic and the continental lithospheres across the transform fault. But this model is compatible neither with numerical computation including flexural behavior of the lithosphere nor with timing of vertical displacements and the lack of heating related to the passing of the oceanic accretion axis as recorded by the Côte d'Ivoire-Ghana marginal ridge. Enhanced models are still needed. They should better take into account the erosion on the continental slope, and the level of coupling

  12. Nonlinear Network Dynamics on Earthquake Fault Systems

    SciTech Connect

    Rundle, Paul B.; Rundle, John B.; Tiampo, Kristy F.; Sa Martins, Jorge S.; McGinnis, Seth; Klein, W.

    2001-10-01

    Earthquake faults occur in interacting networks having emergent space-time modes of behavior not displayed by isolated faults. Using simulations of the major faults in southern California, we find that the physics depends on the elastic interactions among the faults defined by network topology, as well as on the nonlinear physics of stress dissipation arising from friction on the faults. Our results have broad applications to other leaky threshold systems such as integrate-and-fire neural networks.

  13. Tutorial: Advanced fault tree applications using HARP

    NASA Technical Reports Server (NTRS)

    Dugan, Joanne Bechta; Bavuso, Salvatore J.; Boyd, Mark A.

    1993-01-01

    Reliability analysis of fault tolerant computer systems for critical applications is complicated by several factors. These modeling difficulties are discussed and dynamic fault tree modeling techniques for handling them are described and demonstrated. Several advanced fault tolerant computer systems are described, and fault tree models for their analysis are presented. HARP (Hybrid Automated Reliability Predictor) is a software package developed at Duke University and NASA Langley Research Center that is capable of solving the fault tree models presented.

  14. Mantle phase changes and deep-earthquake faulting in subducting lithosphere.

    PubMed

    Kirby, S H; Durham, W B; Stern, L A

    1991-04-12

    Inclined zones of earthquakes are the primary expression of lithosphere subduction. A distinct deep population of subduction-zone earthquakes occurs at depths of 350 to 690 kilometers. At those depths ordinary brittle fracture and frictional sliding, the faulting processes of shallow earthquakes, are not expected. A fresh understanding of these deep earthquakes comes from developments in several areas of experimental and theoretical geophysics, including the discovery and characterization of transformational faulting, a shear instability connected with localized phase transformations under nonhydrostatic stress. These developments support the hypothesis that deep earthquakes represent transformational faulting in a wedge of olivine-rich peridotite that is likely to persist metastably in coldest plate interiors to depths as great as 690 km. Predictions based on this deep structure of mantle phase changes are consistent with the global depth distribution of deep earthquakes, the maximum depths of earthquakes in individual subductions zones, and key source characteristics of deep events. PMID:17769266

  15. Mantle phase changes and deep-earthquake faulting in subducting lithosphere

    USGS Publications Warehouse

    Kirby, S.H.; Durham, W.B.; Stern, L.A.

    1991-01-01

    Inclined zones of earthquakes are the primary expression of lithosphere subduction. A distinct deep population of subduction-zone earthquakes occurs at depths of 350 to 690 kilometers. At those depths ordinary brittle fracture and frictional sliding, the faulting processes of shallow earthquakes, are not expected. A fresh understanding of these deep earthquakes comes from developments in several areas of experimental and theoretical geophysics, including the discovery and characterization of transformational faulting, a shear instability connected with localized phase transformations under nonhydrostatic stress. These developments support the hypothesis that deep earthquakes represent transformational faulting in a wedge of olivine-rich peridotite that is likely to persist metastably in coldest plate interiors to depths as great as 690 km. Predictions based on this deep structure of mantle phase changes are consistent with the global depth distribution of deep earthquakes, the maximum depths of earthquakes in individual subductions zones, and key source characteristics of deep events.

  16. Mantle phase changes and deep-earthquake faulting in subducting lithosphere.

    PubMed

    Kirby, S H; Durham, W B; Stern, L A

    1991-04-12

    Inclined zones of earthquakes are the primary expression of lithosphere subduction. A distinct deep population of subduction-zone earthquakes occurs at depths of 350 to 690 kilometers. At those depths ordinary brittle fracture and frictional sliding, the faulting processes of shallow earthquakes, are not expected. A fresh understanding of these deep earthquakes comes from developments in several areas of experimental and theoretical geophysics, including the discovery and characterization of transformational faulting, a shear instability connected with localized phase transformations under nonhydrostatic stress. These developments support the hypothesis that deep earthquakes represent transformational faulting in a wedge of olivine-rich peridotite that is likely to persist metastably in coldest plate interiors to depths as great as 690 km. Predictions based on this deep structure of mantle phase changes are consistent with the global depth distribution of deep earthquakes, the maximum depths of earthquakes in individual subductions zones, and key source characteristics of deep events.

  17. Effects induced by an earthquake on its fault plane:a boundary element study

    NASA Astrophysics Data System (ADS)

    Bonafede, Maurizio; Neri, Andrea

    2000-04-01

    Mechanical effects left by a model earthquake on its fault plane, in the post-seismic phase, are investigated employing the `displacement discontinuity method'. Simple crack models, characterized by the release of a constant, unidirectional shear traction are investigated first. Both slip components-parallel and normal to the traction direction-are found to be non-vanishing and to depend on fault depth, dip, aspect ratio and fault plane geometry. The rake of the slip vector is similarly found to depend on depth and dip. The fault plane is found to suffer some small rotation and bending, which may be responsible for the indentation of a transform tectonic margin, particularly if cumulative effects are considered. Very significant normal stress components are left over the shallow portion of the fault surface after an earthquake: these are tensile for thrust faults, compressive for normal faults and are typically comparable in size to the stress drop. These normal stresses can easily be computed for more realistic seismic source models, in which a variable slip is assigned; normal stresses are induced in these cases too, and positive shear stresses may even be induced on the fault plane in regions of high slip gradient. Several observations can be explained from the present model: low-dip thrust faults and high-dip normal faults are found to be facilitated, according to the Coulomb failure criterion, in repetitive earthquake cycles; the shape of dip-slip faults near the surface is predicted to be upward-concave; and the shallower aftershock activity generally found in the hanging block of a thrust event can be explained by `unclamping' mechanisms.

  18. GPS measurements of near-field deformation along the southern Dead Sea Fault System

    NASA Astrophysics Data System (ADS)

    Al Tarazi, Eid; Abu Rajab, Jafar; Gomez, Francisco; Cochran, William; Jaafar, Rani; Ferry, Matthieu

    2011-12-01

    Analysis of short-term deformation along the southern part of Dead Sea Fault (DSF) provides a systematic view of kinematics this part of the continental transform. The southern DSF consists of two principal segments: the Wadi Araba and Jordan Valley faults. In addition to other regional continuous GPS data, this study uses new data from 25 survey sites and 4 continuous GPS stations in Jordan for improved near-field observations. Resulting velocities are reported with 1-σ uncertainties ranging from 0.4-1.0 mm/yr. Application of elastic dislocation models yields estimates of slip rates for Wadi Araba and Jordan Valley faults are 4.9 ± 0.4 mm/yr and 4.7 ± 0.4 mm/yr, respectively. Modeling also suggests different depths of effective fault locking with 15 ± 5 km and 8 ± 5 km for the Wadi Araba and Jordan Valley faults, respectively. These slip rates are generally consistent with the upper end of the range of slip rates estimated from late Quaternary geology. Spatial variations in effective fault locking generally correspond with a heterogeneous mantle lithosphere. A similar observation can be observed along the southern San Andreas Fault, and this may reflect the influence of heterogeneity in the uppermost mantle on crustal faulting processes.

  19. Along-Fault Deformation Partitioning of NW Haiti:Implication on Fluid Transfer

    NASA Astrophysics Data System (ADS)

    Ellouz, N.; Hamon, Y.; Deschamps, R.; Schmitz, J.; Battani, A.; Leroy, S. D.; Monplaisir, R.; Ruffine, L.

    2014-12-01

    The area of Western Haiti located in between two major fault systems, the Enriquillo-Plantain Garden Fault (EPGF) and Ciabao-Oriente Septentrional fault system has been surveyed during the 2012 and 2013 Haiti-SIS cruises. From seismic interpretation and mapping the two bordering transform faults systems, EPGF (to the South) and Oriente-Septentrional (to the North), we document the deformation partitioning and the fault segmentation at different scales. A common tectonic evolution has been registered in S. Eastern Cuba and Western Hispaniola (Haiti area), up to early Miocene times. From the effective Hispaniola-Cuba separation at Oligocene/Miocene transition times, left lateral strike-slip motion was registered along large crustal faults cross-cutting different domains versus time. Rooted on these crustal/lithospheric discontinuties tectonic stress is also released on secondary fault systems where both deep and basin, even meteoric fluids may migrate. Sedimentation processes and sequence deposition have been also analyzed both offshore and onshore in the same area showing the strong tectonic-sedimentation processes interaction. A tentative calendar of this deformation, coupled with Present-Day evaluation of the draining areas along Septentrional fault, Transhaitian Ranges and Gonave Bay will be presented on regional seismic profiles and cross-sections.

  20. Data mining based full ceramic bearing fault diagnostic system using AE sensors.

    PubMed

    He, David; Li, Ruoyu; Zhu, Junda; Zade, Mikhail

    2011-12-01

    Full ceramic bearings are considered the first step toward full ceramic, oil-free engines in the future. No research on full ceramic bearing fault diagnostics using acoustic emission (AE) sensors has been reported. Unlike their steel counterparts, signal processing methods to extract effective AE fault characteristic features and fault diagnostic systems for full ceramic bearings have not been developed. In this paper, a data mining based full ceramic bearing diagnostic system using AE based condition indicators (CIs) is presented. The system utilizes a new signal processing method based on Hilbert Huang transform to extract AE fault features for the computation of CIs. These CIs are used to build a data mining based fault classifier using a k-nearest neighbor algorithm. Seeded fault tests on full ceramic bearing outer race, inner race, balls, and cage are conducted on a bearing diagnostic test rig and AE burst data are collected. The effectiveness of the developed fault diagnostic system is validated using real full ceramic bearing seeded fault test data.

  1. Fault Management Guiding Principles

    NASA Technical Reports Server (NTRS)

    Newhouse, Marilyn E.; Friberg, Kenneth H.; Fesq, Lorraine; Barley, Bryan

    2011-01-01

    Regardless of the mission type: deep space or low Earth orbit, robotic or human spaceflight, Fault Management (FM) is a critical aspect of NASA space missions. As the complexity of space missions grows, the complexity of supporting FM systems increase in turn. Data on recent NASA missions show that development of FM capabilities is a common driver for significant cost overruns late in the project development cycle. Efforts to understand the drivers behind these cost overruns, spearheaded by NASA's Science Mission Directorate (SMD), indicate that they are primarily caused by the growing complexity of FM systems and the lack of maturity of FM as an engineering discipline. NASA can and does develop FM systems that effectively protect mission functionality and assets. The cost growth results from a lack of FM planning and emphasis by project management, as well the maturity of FM as an engineering discipline, which lags behind the maturity of other engineering disciplines. As a step towards controlling the cost growth associated with FM development, SMD has commissioned a multi-institution team to develop a practitioner's handbook representing best practices for the end-to-end processes involved in engineering FM systems. While currently concentrating primarily on FM for science missions, the expectation is that this handbook will grow into a NASA-wide handbook, serving as a companion to the NASA Systems Engineering Handbook. This paper presents a snapshot of the principles that have been identified to guide FM development from cradle to grave. The principles range from considerations for integrating FM into the project and SE organizational structure, the relationship between FM designs and mission risk, and the use of the various tools of FM (e.g., redundancy) to meet the FM goal of protecting mission functionality and assets.

  2. Fault Analysis in Solar Photovoltaic Arrays

    NASA Astrophysics Data System (ADS)

    Zhao, Ye

    Fault analysis in solar photovoltaic (PV) arrays is a fundamental task to increase reliability, efficiency and safety in PV systems. Conventional fault protection methods usually add fuses or circuit breakers in series with PV components. But these protection devices are only able to clear faults and isolate faulty circuits if they carry a large fault current. However, this research shows that faults in PV arrays may not be cleared by fuses under some fault scenarios, due to the current-limiting nature and non-linear output characteristics of PV arrays. First, this thesis introduces new simulation and analytic models that are suitable for fault analysis in PV arrays. Based on the simulation environment, this thesis studies a variety of typical faults in PV arrays, such as ground faults, line-line faults, and mismatch faults. The effect of a maximum power point tracker on fault current is discussed and shown to, at times, prevent the fault current protection devices to trip. A small-scale experimental PV benchmark system has been developed in Northeastern University to further validate the simulation conclusions. Additionally, this thesis examines two types of unique faults found in a PV array that have not been studied in the literature. One is a fault that occurs under low irradiance condition. The other is a fault evolution in a PV array during night-to-day transition. Our simulation and experimental results show that overcurrent protection devices are unable to clear the fault under "low irradiance" and "night-to-day transition". However, the overcurrent protection devices may work properly when the same PV fault occurs in daylight. As a result, a fault under "low irradiance" and "night-to-day transition" might be hidden in the PV array and become a potential hazard for system efficiency and reliability.

  3. Evolution of the Rodgers Creek–Maacama right-lateral fault system and associated basins east of the northward-migrating Mendocino Triple Junction, northern California

    USGS Publications Warehouse

    McLaughlin, Robert J.; Sarna-Wojcicki, Andrei M.; Wagner, David L.; Fleck, Robert J.; Langenheim, V.E.; Jachens, Robert C.; Clahan, Kevin; Allen, James R.

    2012-01-01

    The Rodgers Creek–Maacama fault system in the northern California Coast Ranges (United States) takes up substantial right-lateral motion within the wide transform boundary between the Pacific and North American plates, over a slab window that has opened northward beneath the Coast Ranges. The fault system evolved in several right steps and splays preceded and accompanied by extension, volcanism, and strike-slip basin development. Fault and basin geometries have changed with time, in places with younger basins and faults overprinting older structures. Along-strike and successional changes in fault and basin geometry at the southern end of the fault system probably are adjustments to frequent fault zone reorganizations in response to Mendocino Triple Junction migration and northward transit of a major releasing bend in the northern San Andreas fault. The earliest Rodgers Creek fault zone displacement is interpreted to have occurred ca. 7 Ma along extensional basin-forming faults that splayed northwest from a west-northwest proto-Hayward fault zone, opening a transtensional basin west of Santa Rosa. After ca. 5 Ma, the early transtensional basin was compressed and extensional faults were reactivated as thrusts that uplifted the northeast side of the basin. After ca. 2.78 Ma, the Rodgers Creek fault zone again splayed from the earlier extensional and thrust faults to steeper dipping faults with more north-northwest orientations. In conjunction with the changes in orientation and slip mode, the Rodgers Creek fault zone dextral slip rate increased from ∼2–4 mm/yr 7–3 Ma, to 5–8 mm/yr after 3 Ma. The Maacama fault zone is shown from several data sets to have initiated ca. 3.2 Ma and has slipped right-laterally at ∼5–8 mm/yr since its initiation. The initial Maacama fault zone splayed northeastward from the south end of the Rodgers Creek fault zone, accompanied by the opening of several strike-slip basins, some of which were later uplifted and compressed

  4. Organelle transformation.

    PubMed

    Bhattacharya, Anjanabha; Kumar, Anish; Desai, Nirali; Parikh, Seema

    2012-01-01

    The source of genetic information in a plant cell is contained in nucleus, plastids, and mitochondria. Organelle transformation is getting a lot of attention nowadays because of its superior performance over the conventional and most commonly used nuclear transformation for obtaining transgenic lines. Absence of gene silencing, strong predictable transgene expression, and its application in molecular pharming, both in pharmaceutical and nutraceuticals, are some of many advantages. Other important benefits of utilizing this technology include the absence of transgene flow, as organelles are maternally inherited. This may increase the acceptability of organelle transformation technology in the development of transgenic crops in a wider scale all over the globe. As the need for crop productivity and therapeutic compounds increases, organelle transformation may be able to bridge the gap, thereby having a definite promise for the future.

  5. Triple transformation

    NASA Astrophysics Data System (ADS)

    Khan, Farrukh I.; Schinn, Dustin S.

    2013-08-01

    A new business plan that enables policy transformation and resource mobilization at the national and international level, while improving access to resources, will allow the Green Climate Fund to integrate development goals and action on climate change.

  6. Organelle transformation.

    PubMed

    Bhattacharya, Anjanabha; Kumar, Anish; Desai, Nirali; Parikh, Seema

    2012-01-01

    The source of genetic information in a plant cell is contained in nucleus, plastids, and mitochondria. Organelle transformation is getting a lot of attention nowadays because of its superior performance over the conventional and most commonly used nuclear transformation for obtaining transgenic lines. Absence of gene silencing, strong predictable transgene expression, and its application in molecular pharming, both in pharmaceutical and nutraceuticals, are some of many advantages. Other important benefits of utilizing this technology include the absence of transgene flow, as organelles are maternally inherited. This may increase the acceptability of organelle transformation technology in the development of transgenic crops in a wider scale all over the globe. As the need for crop productivity and therapeutic compounds increases, organelle transformation may be able to bridge the gap, thereby having a definite promise for the future. PMID:22610643

  7. River Captures and Erosional Disequilibrium Along Strike-slip Faults

    NASA Astrophysics Data System (ADS)

    Brocard, G. Y.; Fayon, A. K.; Perg, L. A.; Paola, C.; Teyssier, C.; Whitney, D. L.; Mota, M.; Moran-Ical, S.

    2005-12-01

    River captures are internal instabilities of erosion systems and are inherently promoted by strike-slip faulting. A capture event can generate a wave of incision that propagates from the capture site upstream and/or downstream, resulting in an increased bulk erosion rate around the capture site. Thus, under steady boundary conditions, drainage diversions trigger pulses of erosion, sediment production, rock exhumation and isostatic rebound. Therefore, a significant part of the erosion in oblique tectonics can be achieved in a state of significant departure from short-term dynamic equilibrium. The frequency, intensity, and duration of these events set the timescale over which their integrated effects can be regarded as the expression of a long-term dynamic equilibrium. We are investigating the effects of a large river capture on the oblique collision between the North American and Caribbean plates in Guatemala. Several thousands of kilometers of strike-slip displacement have been accommodated along this boundary during the Tertiary. The deformation is now concentrated mostly along the E-W Motagua strike-slip fault. Oblique tectonics is discernable within a 50 km wide topographic belt, north of this fault (Sierra de las Minas - Sierra de Chuacus range). On the northern flank of this range, deformation includes 130 km offset across the Polochic strike-slip fault, documented by both geological structures and drainage patterns. Numerous elbows and dry valleys show the progressive transformation of the initial transverse (S-N) drainage crossing the fault into a transverse-parallel (E-W) system that developed during increasing displacement along the fault. The drainage reorganization operates by river lengthening, captures, and avulsions. One of the latest capture sites is surrounded by a large (110x30 km) zone of deeply (1500 m) dissected landscape that coincides with the captured catchment. This zone sharply contrasts with the surrounding areas where large fragments of a

  8. Software reliability through fault-avoidance and fault-tolerance

    NASA Technical Reports Server (NTRS)

    Vouk, Mladen A.; Mcallister, David F.

    1991-01-01

    Twenty independently developed but functionally equivalent software versions were used to investigate and compare empirically some properties of N-version programming, Recovery Block, and Consensus Recovery Block, using the majority and consensus voting algorithms. This was also compared with another hybrid fault-tolerant scheme called Acceptance Voting, using dynamic versions of consensus and majority voting. Consensus voting provides adaptation of the voting strategy to varying component reliability, failure correlation, and output space characteristics. Since failure correlation among versions effectively reduces the cardinality of the space in which the voter make decisions, consensus voting is usually preferable to simple majority voting in any fault-tolerant system. When versions have considerably different reliabilities, the version with the best reliability will perform better than any of the fault-tolerant techniques.

  9. Three-dimensional Allan fault plane analysis

    SciTech Connect

    Hoffman, K.S.; Taylor, D.R.; Schnell, R.T.

    1994-12-31

    Allan fault-plane analysis is a useful tool for determining hydrocarbon migration paths and the location of possible traps. While initially developed for Gulf coast deltaic and interdeltaic environments, fault-plane analysis has been successfully applied in many other geologic settings. Where the geology involves several intersecting faults and greater complexity, many two-dimensional displays are required in the investigation and it becomes increasingly difficult to accurately visualize both fault relationships and migration routes. Three-dimensional geospatial fault and structure modeling using computer techniques, however, facilitates both visualization and understanding and extends fault-plane analysis into much more complex situations. When a model is viewed in three dimensions, the strata on both sides of a fault can be seen simultaneously while the true structural character of one or more fault surfaces is preserved. Three-dimensional analysis improves the speed and accuracy of the fault plane methodology.

  10. Fault Diagnosis for Rotating Machinery: A Method based on Image Processing

    PubMed Central

    Lu, Chen; Wang, Yang; Ragulskis, Minvydas; Cheng, Yujie

    2016-01-01

    Rotating machinery is one of the most typical types of mechanical equipment and plays a significant role in industrial applications. Condition monitoring and fault diagnosis of rotating machinery has gained wide attention for its significance in preventing catastrophic accident and guaranteeing sufficient maintenance. With the development of science and technology, fault diagnosis methods based on multi-disciplines are becoming the focus in the field of fault diagnosis of rotating machinery. This paper presents a multi-discipline method based on image-processing for fault diagnosis of rotating machinery. Different from traditional analysis method in one-dimensional space, this study employs computing method in the field of image processing to realize automatic feature extraction and fault diagnosis in a two-dimensional space. The proposed method mainly includes the following steps. First, the vibration signal is transformed into a bi-spectrum contour map utilizing bi-spectrum technology, which provides a basis for the following image-based feature extraction. Then, an emerging approach in the field of image processing for feature extraction, speeded-up robust features, is employed to automatically exact fault features from the transformed bi-spectrum contour map and finally form a high-dimensional feature vector. To reduce the dimensionality of the feature vector, thus highlighting main fault features and reducing subsequent computing resources, t-Distributed Stochastic Neighbor Embedding is adopt to reduce the dimensionality of the feature vector. At last, probabilistic neural network is introduced for fault identification. Two typical rotating machinery, axial piston hydraulic pump and self-priming centrifugal pumps, are selected to demonstrate the effectiveness of the proposed method. Results show that the proposed method based on image-processing achieves a high accuracy, thus providing a highly effective means to fault diagnosis for rotating machinery. PMID

  11. Temporal and spatial late Quaternary slip rate variability on the southern San Jacinto fault, California

    NASA Astrophysics Data System (ADS)

    Le, K.; Oskin, M.; Rockwell, T.; Owen, L.

    2008-12-01

    The history of the San Jacinto fault in accommodating Pacific-North America plate motion illustrates how deformation is partitioned in time and space across transform fault systems. We present new slip rate results from alluvial fans displaced by two parallel strands of the southern San Jacinto fault zone: the Clark and Coyote Creek faults. Alluvial fans were mapped in the field with 'B4' LiDAR imagery and dated using cosmogenic 10Be. We find that slip rates 1) varied synchronously by a factor of two over the past ~35 kyr and 2) change significantly along strike as slip is transferred southwestward from the Clark fault to the Coyote Creek fault. 35 ka to present average dextral slip rates for the Clark fault are 5.4 ± 2.2 mm/yr at the Rockhouse Canyon and 1.5 ± 0.4 mm/yr farther southeast, near the southern Santa Rosa Mountains. Over the same time period, the slip rate for the Coyote Creek fault is 2.9 ± 1.0 mm/yr. This yields a combined average slip-rate of 8.3 ± 2.2 mm/yr for the San Jacinto fault zone over the past ~35 kyr. Mid-Holocene to present rates are significantly faster along both fault strands. Displaced ~3-4 ka alluvial fans show that the Clark fault slips at a rate of 7.3 ± 1.8 mm/yr at Rockhouse Canyon and 3.9 ± 1.4 mm/yr at the southern Santa Rosa Mountians. Along the Coyote Creek fault the slip rate is 8.6 ± 2.9 mm/yr over the past ~3 ka. The combined Holocene rate of 15.9 ± 4.7 mm/yr is consistent with geodetic slip-rate estimates of 15 to 21 mm/yr for the San Jacinto fault zone. The apparently synchronous variation of slip-rate along both strands of the San Jacinto fault suggests that the rate of loading across the fault zone has varied significantly over the past ~35 kyr.

  12. Quaternary faults of west Texas

    SciTech Connect

    Collins, E.W.; Raney, J.A. . Bureau of Economic Geology)

    1993-04-01

    North- and northwest-striking intermontane basins and associated normal faults in West Texas and adjacent Chihuahua, Mexico, formed in response to Basin and Range tectonism that began about 24 Ma ago. Data on the precise ages of faulted and unfaulted Quaternary deposits are sparse. However, age estimates made on the basis of field stratigraphic relationships and the degree of calcic soil development have helped determine that many of the faults that bound the basin margins ruptured since the middle Pleistocene and that some faults probably ruptured during the Holocene. Average recurrence intervals between surface ruptures since the middle Pleistocene appear to be relatively long, about 10,000 to 100,000 yr. Maximum throw during single rupture events have been between 1 and 3 m. Historic seismicity in West Texas is low compared to seismicity in many parts of the Basin and Range province. The largest historic earthquake, the 1931 Valentine earthquake in Ryan Flat/Lobo Valley, had a magnitude of 6.4 and no reported surface rupture. The most active Quaternary faults occur within the 120-km-long Hueco Bolson, the 70-km-long Red Light Bolson, and the > 200-km-long Salt Basins/Wild Horse Flat/Lobo Valley/Ryan Flat.

  13. Reconsidering Fault Slip Scaling

    NASA Astrophysics Data System (ADS)

    Gomberg, J. S.; Wech, A.; Creager, K. C.; Obara, K.; Agnew, D. C.

    2015-12-01

    The scaling of fault slip events given by the relationship between the scalar moment M0, and duration T, potentially provides key constraints on the underlying physics controlling slip. Many studies have suggested that measurements of M0 and T are related as M0=KfT3 for 'fast' slip events (earthquakes) and M0=KsT for 'slow' slip events, in which Kf and Ks are proportionality constants, although some studies have inferred intermediate relations. Here 'slow' and 'fast' refer to slip front propagation velocities, either so slow that seismic radiation is too small or long period to be measurable or fast enough that dynamic processes may be important for the slip process and measurable seismic waves radiate. Numerous models have been proposed to explain the differing M0-T scaling relations. We show that a single, simple dislocation model of slip events within a bounded slip zone may explain nearly all M0-T observations. Rather than different scaling for fast and slow populations, we suggest that within each population the scaling changes from M0 proportional to T3 to T when the slipping area reaches the slip zone boundaries and transitions from unbounded, 2-dimensional to bounded, 1-dimensional growth. This transition has not been apparent previously for slow events because data have sampled only the bounded regime and may be obscured for earthquakes when observations from multiple tectonic regions are combined. We have attempted to sample the expected transition between bounded and unbounded regimes for the slow slip population, measuring tremor cluster parameters from catalogs for Japan and Cascadia and using them as proxies for small slow slip event characteristics. For fast events we employed published earthquake slip models. Observations corroborate our hypothesis, but highlight observational difficulties. We find that M0-T observations for both slow and fast slip events, spanning 12 orders of magnitude in M0, are consistent with a single model based on dislocation

  14. Where's the Hayward Fault? A Green Guide to the Fault

    USGS Publications Warehouse

    Stoffer, Philip W.

    2008-01-01

    This report describes self-guided field trips to one of North America?s most dangerous earthquake faults?the Hayward Fault. Locations were chosen because of their easy access using mass transit and/or their significance relating to the natural and cultural history of the East Bay landscape. This field-trip guidebook was compiled to help commemorate the 140th anniversary of an estimated M 7.0 earthquake that occurred on the Hayward Fault at approximately 7:50 AM, October 21st, 1868. Although many reports and on-line resources have been compiled about the science and engineering associated with earthquakes on the Hayward Fault, this report has been prepared to serve as an outdoor guide to the fault for the interested public and for educators. The first chapter is a general overview of the geologic setting of the fault. This is followed by ten chapters of field trips to selected areas along the fault, or in the vicinity, where landscape, geologic, and man-made features that have relevance to understanding the nature of the fault and its earthquake history can be found. A glossary is provided to define and illustrate scientific term used throughout this guide. A ?green? theme helps conserve resources and promotes use of public transportation, where possible. Although access to all locations described in this guide is possible by car, alternative suggestions are provided. To help conserve paper, this guidebook is available on-line only; however, select pages or chapters (field trips) within this guide can be printed separately to take along on an excursion. The discussions in this paper highlight transportation alternatives to visit selected field trip locations. In some cases, combinations, such as a ride on BART and a bus, can be used instead of automobile transportation. For other locales, bicycles can be an alternative means of transportation. Transportation descriptions on selected pages are intended to help guide fieldtrip planners or participants choose trip

  15. Maximum spectral demands in the near-fault region

    USGS Publications Warehouse

    Huang, Yin-Nan; Whittaker, Andrew S.; Luco, Nicolas

    2008-01-01

    The Next Generation Attenuation (NGA) relationships for shallow crustal earthquakes in the western United States predict a rotated geometric mean of horizontal spectral demand, termed GMRotI50, and not maximum spectral demand. Differences between strike-normal, strike-parallel, geometric-mean, and maximum spectral demands in the near-fault region are investigated using 147 pairs of records selected from the NGA strong motion database. The selected records are for earthquakes with moment magnitude greater than 6.5 and for closest site-to-fault distance less than 15 km. Ratios of maximum spectral demand to NGA-predicted GMRotI50 for each pair of ground motions are presented. The ratio shows a clear dependence on period and the Somerville directivity parameters. Maximum demands can substantially exceed NGA-predicted GMRotI50 demands in the near-fault region, which has significant implications for seismic design, seismic performance assessment, and the next-generation seismic design maps. Strike-normal spectral demands are a significantly unconservative surrogate for maximum spectral demands for closest distance greater than 3 to 5 km. Scale factors that transform NGA-predicted GMRotI50 to a maximum spectral demand in the near-fault region are proposed.

  16. Maximum spectral demands in the near-fault region

    USGS Publications Warehouse

    Huang, Y.-N.; Whittaker, A.S.; Luco, N.

    2008-01-01

    The Next Generation Attenuation (NGA) relationships for shallow crustal earthquakes in the western United States predict a rotated geometric mean of horizontal spectral demand, termed GMRotI50, and not maximum spectral demand. Differences between strike-normal, strike-parallel, geometric-mean, and maximum spectral demands in the near-fault region are investigated using 147 pairs of records selected from the NGA strong motion database. The selected records are for earthquakes with moment magnitude greater than 6.5 and for closest site-to-fault distance less than 15 km. Ratios of maximum spectral demand to NGA-predicted GMRotI50 for each pair of ground motions are presented. The ratio shows a clear dependence on period and the Somerville directivity parameters. Maximum demands can substantially exceed NGA-predicted GMRotI50 demands in the near-fault region, which has significant implications for seismic design, seismic performance assessment, and the next-generation seismic design maps. Strike-normal spectral demands are a significantly unconservative surrogate for maximum spectral demands for closest distance greater than 3 to 5 km. Scale factors that transform NGA-predicted GMRotI50 to a maximum spectral demand in the near-fault region are proposed. ?? 2008, Earthquake Engineering Research Institute.

  17. Petri net modeling of fault analysis for probabilistic risk assessment

    NASA Astrophysics Data System (ADS)

    Lee, Andrew

    Fault trees and event trees have been widely accepted as the modeling strategy to perform Probabilistic Risk Assessment (PRA). However, there are several limitations associated with fault tree/event tree modeling. These include 1. It only considers binary events; 2. It assumes independence among basic events; and 3. It does not consider timing sequence of basic events. This thesis investigates Petri net modeling as a potential alternative for PRA modeling. Petri nets have mainly been used as a simulation tool for queuing and network systems. However, it has been suggested that they could also model failure scenarios, and thus could be a potential modeling strategy for PRA. In this thesis, the transformations required to model logic gates in a fault tree by Petri nets are explored. The gap between fault tree analysis and Petri net analysis is bridged through gate equivalency analysis. Methods for qualitative and quantitative analysis for Petri nets are presented. Techniques are developed and implemented to revise and tailor traditional Petri net modeling for system failure analysis. The airlock system and the maintenance cooling system of a CANada Deuterium Uranium (CANDU) reactor are used as case studies to demonstrate Petri nets ability to model system failure and provide a structured approach for qualitative and quantitative analysis. The minimal cutsets and the probability of the airlock system failing to maintain the pressure boundary are obtained. Furthermore, the case study is extended to non-coherent system analysis due to system maintenance.

  18. Model Transformation for a System of Systems Dependability Safety Case

    NASA Technical Reports Server (NTRS)

    Murphy, Judy; Driskell, Stephen B.

    2010-01-01

    Software plays an increasingly larger role in all aspects of NASA's science missions. This has been extended to the identification, management and control of faults which affect safety-critical functions and by default, the overall success of the mission. Traditionally, the analysis of fault identification, management and control are hardware based. Due to the increasing complexity of system, there has been a corresponding increase in the complexity in fault management software. The NASA Independent Validation & Verification (IV&V) program is creating processes and procedures to identify, and incorporate safety-critical software requirements along with corresponding software faults so that potential hazards may be mitigated. This Specific to Generic ... A Case for Reuse paper describes the phases of a dependability and safety study which identifies a new, process to create a foundation for reusable assets. These assets support the identification and management of specific software faults and, their transformation from specific to generic software faults. This approach also has applications to other systems outside of the NASA environment. This paper addresses how a mission specific dependability and safety case is being transformed to a generic dependability and safety case which can be reused for any type of space mission with an emphasis on software fault conditions.

  19. Fault diagnosis based on continuous simulation models

    NASA Technical Reports Server (NTRS)

    Feyock, Stefan

    1987-01-01

    The results are described of an investigation of techniques for using continuous simulation models as basis for reasoning about physical systems, with emphasis on the diagnosis of system faults. It is assumed that a continuous simulation model of the properly operating system is available. Malfunctions are diagnosed by posing the question: how can we make the model behave like that. The adjustments that must be made to the model to produce the observed behavior usually provide definitive clues to the nature of the malfunction. A novel application of Dijkstra's weakest precondition predicate transformer is used to derive the preconditions for producing the required model behavior. To minimize the size of the search space, an envisionment generator based on interval mathematics was developed. In addition to its intended application, the ability to generate qualitative state spaces automatically from quantitative simulations proved to be a fruitful avenue of investigation in its own right. Implementations of the Dijkstra transform and the envisionment generator are reproduced in the Appendix.

  20. Transient Faults in Computer Systems

    NASA Technical Reports Server (NTRS)

    Masson, Gerald M.

    1993-01-01

    A powerful technique particularly appropriate for the detection of errors caused by transient faults in computer systems was developed. The technique can be implemented in either software or hardware; the research conducted thus far primarily considered software implementations. The error detection technique developed has the distinct advantage of having provably complete coverage of all errors caused by transient faults that affect the output produced by the execution of a program. In other words, the technique does not have to be tuned to a particular error model to enhance error coverage. Also, the correctness of the technique can be formally verified. The technique uses time and software redundancy. The foundation for an effective, low-overhead, software-based certification trail approach to real-time error detection resulting from transient fault phenomena was developed.

  1. Instantaneous fault frequencies estimation in roller bearings via wavelet structures

    NASA Astrophysics Data System (ADS)

    Rodopoulos, Konstantinos I.; Antoniadis, Ioannis A.

    2016-11-01

    The main target of the current paper is the effective application of the method proposed in "Antoniadis et al. (2014) [17], in roller bearings under variable speed. For this reason, roller bearing model with slip and real data coming from a test rig has been used. The method extracts useful information from a complicated signal where the overlap among the harmonics can raise up to 30%. According to the proposed method, a set of wavelet transforms of the signal is first obtained, using a structure of Complex Shifted Morlet Wavelets. The center frequencies and the bandwidths of the individual wavelets, as well as the number of wavelets used, are associated with the characteristic fault frequency and its harmonic components. In this way, a set of complex signals result in the time domain, equal to the number of the wavelets used. Then, the instantaneous frequencies of the signals are estimated by applying an appropriate subspace algorithm (as for e.g. ESPRIT), to the entire set of the resulting complex wavelet transforms, exploiting the corresponding subspace rotational invariance property of this set of complex signals. The iterative procedure brings up accurate results from complicated signals, separating the fault associated signal components. Also, the spectrograms of the processed signals confirm the ability to match excited areas with specific faults.

  2. Interplay between magmatic accretion, spreading asymmetry and detachment faulting at a segment end: Crustal structure south of the Ascension Fracture Zone

    NASA Astrophysics Data System (ADS)

    Bialas, Jörg; Dannowski, Anke; Reston, Timothy J.

    2015-12-01

    A wide-angle seismic section across the Mid-Atlantic Ridge just south of the Ascension transform system reveals laterally varying crustal thickness, and to the east a strongly distorted Moho that appears to result from slip along a large-offset normal fault, termed an oceanic detachment fault. Gravity modelling supports the inferred crustal structure. We investigate the interplay between magmatism, detachment faulting and the changing asymmetry of crustal accretion, and consider several possible scenarios. The one that appears most likely is remarkably simple: an episode of detachment faulting which accommodates all plate divergence and results in the westward migration of the ridge axis, is interspersed with dominantly magmatic and moderately asymmetric (most on the western side) spreading which moves the spreading axis back towards the east. Following the runaway weakening of a normal fault and its development into an oceanic detachment fault, magma both intrudes the footwall to the fault, producing a layer of gabbro (subsequently partially exhumed).

  3. InSAR measurements around active faults: creeping Philippine Fault and un-creeping Alpine Fault

    NASA Astrophysics Data System (ADS)

    Fukushima, Y.

    2013-12-01

    Recently, interferometric synthetic aperture radar (InSAR) time-series analyses have been frequently applied to measure the time-series of small and quasi-steady displacements in wide areas. Large efforts in the methodological developments have been made to pursue higher temporal and spatial resolutions by using frequently acquired SAR images and detecting more pixels that exhibit phase stability. While such a high resolution is indispensable for tracking displacements of man-made and other small-scale structures, it is not necessarily needed and can be unnecessarily computer-intensive for measuring the crustal deformation associated with active faults and volcanic activities. I apply a simple and efficient method to measure the deformation around the Alpine Fault in the South Island of New Zealand, and the Philippine Fault in the Leyte Island. I use a small-baseline subset (SBAS) analysis approach (Berardino, et al., 2002). Generally, the more we average the pixel values, the more coherent the signals are. Considering that, for the deformation around active faults, the spatial resolution can be as coarse as a few hundred meters, we can severely 'multi-look' the interferograms. The two applied cases in this study benefited from this approach; I could obtain the mean velocity maps on practically the entire area without discarding decorrelated areas. The signals could have been only partially obtained by standard persistent scatterer or single-look small-baseline approaches that are much more computer-intensive. In order to further increase the signal detection capability, it is sometimes effective to introduce a processing algorithm adapted to the signal of interest. In an InSAR time-series processing, one usually needs to set the reference point because interferograms are all relative measurements. It is difficult, however, to fix the reference point when one aims to measure long-wavelength deformation signals that span the whole analysis area. This problem can be

  4. Update: San Andreas Fault experiment

    NASA Technical Reports Server (NTRS)

    Christodoulidis, D. C.; Smith, D. E.

    1984-01-01

    Satellite laser ranging techniques are used to monitor the broad motion of the tectonic plates comprising the San Andreas Fault System. The San Andreas Fault Experiment, (SAFE), has progressed through the upgrades made to laser system hardware and an improvement in the modeling capabilities of the spaceborne laser targets. Of special note is the launch of the Laser Geodynamic Satellite, LAGEOS spacecraft, NASA's only completely dedicated laser satellite in 1976. The results of plate motion projected into this 896 km measured line over the past eleven years are summarized and intercompared.

  5. High-Resolution LiDAR Topography of the Plate-Boundary Faults in Northern California

    NASA Astrophysics Data System (ADS)

    Prentice, C. S.; Phillips, D. A.; Furlong, K. P.; Brown, A.; Crosby, C. J.; Bevis, M.; Shrestha, R.; Sartori, M.; Brocher, T. M.; Brown, J.

    2007-12-01

    GeoEarthScope acquired more than 1500 square km of airborne LiDAR data in northern California, providing high-resolution topographic data of most of the major strike-slip faults in the region. The coverage includes the San Andreas Fault from its northern end near Shelter Cove to near Parkfield, as well as the Rodgers Creek, Maacama, Calaveras, Green Valley, Paicines, and San Gregorio Faults. The Hayward fault was added with funding provided by the US Geological Survey, the City of Berkeley, and the San Francisco Public Utilities Commission. Data coverage is typically one kilometer in width, centered on the fault. In areas of particular fault complexity the swath width was increased to two kilometers, and in selected areas swath width is as wide as five kilometers. A five-km-wide swath was flown perpendicular to the plate boundary immediately south of Cape Mendocino to capture previously unidentified faults and to understand off-fault deformation associated with the transition zone between the transform margin and the Cascadia subduction zone. The data were collected in conjunction with an intensive GPS campaign designed to improve absolute data accuracy and provide quality control. Data processing to classify the LiDAR point data by return type allows users to filter out vegetation and produce high-resolution DEMs of the ground surface beneath forested regions, revealing geomorphic features along and adjacent to the faults. These data will allow more accurate mapping of fault traces in regions where the vegetation canopy has hampered this effort in the past. In addition, the data provide the opportunity to locate potential sites for detailed paleoseismic studies aimed at providing slip rates and event chronologies. The GeoEarthScope LiDAR data will be made available via an interactive data distribution and processing workflow currently under development.

  6. Application of an improved kurtogram method for fault diagnosis of rolling element bearings

    NASA Astrophysics Data System (ADS)

    Lei, Yaguo; Lin, Jing; He, Zhengjia; Zi, Yanyang

    2011-07-01

    Kurtogram, due to the superiority of detecting and characterizing transients in a signal, has been proved to be a very powerful and practical tool in machinery fault diagnosis. Kurtogram, based on the short time Fourier transform (STFT) or FIR filters, however, limits the accuracy improvement of kurtogram in extracting transient characteristics from a noisy signal and identifying machinery fault. Therefore, more precise filters need to be developed and incorporated into the kurtogram method to overcome its shortcomings and to further enhance its accuracy in discovering characteristics and detecting faults. The filter based on wavelet packet transform (WPT) can filter out noise and precisely match the fault characteristics of noisy signals. By introducing WPT into kurtogram, this paper proposes an improved kurtogram method adopting WPT as the filter of kurtogram to overcome the shortcomings of the original kurtogram. The vibration signals collected from rolling element bearings are used to demonstrate the improved performance of the proposed method compared with the original kurtogram. The results verify the effectiveness of the method in extracting fault characteristics and diagnosing faults of rolling element bearings.

  7. Maximum Magnitude in Relation to Mapped Fault Length and Fault Rupture

    NASA Astrophysics Data System (ADS)

    Black, N.; Jackson, D.; Rockwell, T.

    2004-12-01

    Earthquake hazard zones are highlighted using known fault locations and an estimate of the fault's maximum magnitude earthquake. Magnitude limits are commonly determined from fault geometry, which is dependent on fault length. Over the past 30 years it has become apparent that fault length is often poorly constrained and that a single event can rupture across several individual fault segments. In this study fault geometries are analyzed before and after several moderate to large magnitude earthquakes to determine how well fault length can accurately assess seismic hazard. Estimates of future earthquake magnitudes are often inferred from prior determinations of fault length, but use magnitude regressions based on rupture length. However, rupture length is not always limited to the previously estimated fault length or contained on a single fault. Therefore, the maximum magnitude for a fault may be underestimated, unless the geometry and segmentation of faulting is completely understood. This study examines whether rupture/fault length can be used to accurately predict the maximum magnitude for a given fault. We examine earthquakes greater than 6.0 that occurred after 1970 in Southern California. Geologic maps, fault evaluation reports, and aerial photos that existed prior to these earthquakes are used to obtain the pre-earthquake fault lengths. Pre-earthquake fault lengths are compared with rupture lengths to determine: 1) if fault lengths are the same before and after the ruptures and 2) to constrain the geology and geometry of ruptures that propagated beyond the originally recognized endpoints of a mapped fault. The ruptures examined in this study typically follow one of the following models. The ruptures are either: 1) contained within the dimensions of the original fault trace, 2) break through one or both end points of the originally mapped fault trace, or 3) break through multiple faults, connecting segments into one large fault line. No rupture simply broke a

  8. Structure of the San Andreas Fault at SAFOD (Invited)

    NASA Astrophysics Data System (ADS)

    Chester, J. S.; Chester, F. M.; Sills, D. W.; Heron, B.; Almeida, R. V.; Guillemette, R. N.

    2010-12-01

    The San Andreas Fault Observatory at Depth (SAFOD) provides a unique opportunity to characterize the deformation of sedimentary and crystalline rocks subjected to variable loading rates and chemically reactive fluids at seismogenic depths along an active continental transform fault. The spot core captured relatively undeformed host rock, highly fractured and sheared rock from within the fault zone, and gouge from two prominent zones of aseismic creep, the Southwestern Deforming Zone (SDZ), and the Central Deforming Zone (CDZ). Distinct structural units sampled from west to east, include: (i) deformed crystalline rock west of the active zone, (ii) a fault-bordering damage zone composed of two distinct, highly fractured and cemented arkosic sandstones, (iii) a fault core associated with the SDZ composed of foliated cataclasites, gouge, and variably sheared siltstones and shales, (iv) deformed siltstones and shales within the central portion of the low velocity zone, and (v) the gouge associated with the CDZ. We have characterized the structure and syndeformation-alteration reactions of these units through detailed mapping at the mesoscopic and microscopic scales, XCT imaging, scanning electron microscopy, and elemental mapping. The San Andreas Fault zone at SAFOD is a broad zone of damage containing multiple fault-cores that juxtapose distinct structural-petrologc units. Multiple episodes of fracture, chemically-assisted comminution, neomineralization, and fault healing through cementation are evident. The SDZ and CDZ are composed of distinct 1-3 m-thick layers of incohesive, foliated fault gouge containing survior clasts up to 4 cm in diameter. Deformation of the gouge is relatively homogeneous at mesoscopic scale, occurring by slip along penetrative anastomosing polished shears that often occur at the boundaries of the survivor clasts. We suggest that 1) the extremely low frictional strength of the gouge reflects slip in shears containing a significant fraction of

  9. Transformational leadership.

    PubMed

    Taccetta-Chapnick, M

    1996-01-01

    Rapid changes in the health care system have caused competition among institutions, as organizations are restructured to increase client satisfaction, resulting in the need for a new style of leadership. The transformational leader communicates the mission and vision of the organization and empowers others to effectively resolve conflicts that may arise with change. The health care team that can cope with changes and conflicts views restructuring as a positive transaction and approaches client satisfaction with energy and motivation. Institutions with transformational leadership are the ones that will survive the transition.

  10. Earthquake cycle on the Ballenas Fault, Central Gulf of California, MX

    NASA Astrophysics Data System (ADS)

    Malservisi, R.; Plattner, C.; Hackl, M.; Gonzalez-Garcia, J. J.; Suarez Vidal, F.; Amelung, F.; Dixon, T. H.

    2009-12-01

    South of the San Andreas Fault system, ~90% of the North America/Pacific plate motion is accommodate along the Gulf of California. Here the plate boundary deformation is partitioned in deep basins, often resulting in formation of new oceanic crust, connected by long transform faults. In the central part of the Gulf, one of these transform fault, the Ballenas fault, is localized in the Canales de Ballenas, a ~30 km wide channel between Isla Angel de la Garda and mainland Baja California. The presence of land on both the sides of this marine transform fault give the unique opportunity to perform geodetic study across its trace. On August 3rd 2009, a series of seismic strike slip events (including a M6.9) happened along this segment of plate boundary allowing a combined study of co- and inter- seismic deformation. Here we present the results from 5 years of EGPS along two transects perpendicular to the plate motion direction at 29 and 28 degrees North. These surveys include at least 3 occupations before the seismic event and at least 1 occupation after the earthquake. The analysis of the inter-seismic data shows that ~46 mm/yr is accommodated within the Canales de Ballenas. Co-seismic data are being collected at the time of the deadline for this abstract and will be presented at the meeting in combination with InSar signal.

  11. Distributed fault tolerance in optimal interpolative nets.

    PubMed

    Simon, D

    2001-01-01

    The recursive training algorithm for the optimal interpolative (OI) classification network is extended to include distributed fault tolerance. The conventional OI Net learning algorithm leads to network weights that are nonoptimally distributed (in the sense of fault tolerance). Fault tolerance is becoming an increasingly important factor in hardware implementations of neural networks. But fault tolerance is often taken for granted in neural networks rather than being explicitly accounted for in the architecture or learning algorithm. In addition, when fault tolerance is considered, it is often accounted for using an unrealistic fault model (e.g., neurons that are stuck on or off rather than small weight perturbations). Realistic fault tolerance can be achieved through a smooth distribution of weights, resulting in low weight salience and distributed computation. Results of trained OI Nets on the Iris classification problem show that fault tolerance can be increased with the algorithm presented in this paper.

  12. An experimental study of memory fault latency

    NASA Technical Reports Server (NTRS)

    Chillarege, Ram; Iyer, Ravi K.

    1989-01-01

    The difficulty with the measurement of fault latency is due to the lack of observability of the fault occurrence and error generation instants in a production environment. The authors describe an experiment, using data from a VAX 11/780 under real workload, to study fault latency in the memory subsystem accurately. Fault latency distributions are generated for stuck-at-zero (s-a-0) and stuck-at-one (s-a-1) permanent fault models. The results show that the mean fault latency of an s-a-0 fault is nearly five times that of the s-a-1 fault. An analysis of variance is performed to quantify the relative influence of different workload measures on the evaluated latency.

  13. The fault-tolerant multiprocessor computer

    SciTech Connect

    Smith, T.B. III; Lala, J.H.; Goldberg, J.; Kautz, W.H.; Melliar-Smith, P.M.; Green, M.W.; Levitt, K.N.; Schwartz, R.L.; Weinstock, C.B.; Palumbo, D.; Butler, R.W.

    1986-01-01

    This book presents studies of two fault-tolerant computer systems designed to meet the extreme reliability requirements for safety- critical functions in advanced NASA vehicles , plus a study of potential architectures for future flight control fault-tolerant systems, which might succeed the current generation of computers. While it is understood that these studies were done for NASA, they also have practical commercial applicability. The fault-tolerant multiprocessor (FTMP) architecture is a high reliability computer concept. The basic organization of the FTMP is that of a general purpose homogeneous multiprocessor. Three processors operate on a shared system (memory and l/O) bus. Replication and tight synchronization of all elements and hardware voting are employed to detect and correct any single fault. Reconfiguration is then employed to ''repair'' a fault. Multiple faults may be tolerated as a sequence of single faults with repair between fault occurrences.

  14. Parametric Modeling and Fault Tolerant Control

    NASA Technical Reports Server (NTRS)

    Wu, N. Eva; Ju, Jianhong

    2000-01-01

    Fault tolerant control is considered for a nonlinear aircraft model expressed as a linear parameter-varying system. By proper parameterization of foreseeable faults, the linear parameter-varying system can include fault effects as additional varying parameters. A recently developed technique in fault effect parameter estimation allows us to assume that estimates of the fault effect parameters are available on-line. Reconfigurability is calculated for this model with respect to the loss of control effectiveness to assess the potentiality of the model to tolerate such losses prior to control design. The control design is carried out by applying a polytopic method to the aircraft model. An error bound on fault effect parameter estimation is provided, within which the Lyapunov stability of the closed-loop system is robust. Our simulation results show that as long as the fault parameter estimates are sufficiently accurate, the polytopic controller can provide satisfactory fault-tolerance.

  15. Hidden Markov models for fault detection in dynamic systems

    NASA Technical Reports Server (NTRS)

    Smyth, Padhraic J. (Inventor)

    1995-01-01

    The invention is a system failure monitoring method and apparatus which learns the symptom-fault mapping directly from training data. The invention first estimates the state of the system at discrete intervals in time. A feature vector x of dimension k is estimated from sets of successive windows of sensor data. A pattern recognition component then models the instantaneous estimate of the posterior class probability given the features, p(w(sub i) (vertical bar)/x), 1 less than or equal to i isless than or equal to m. Finally, a hidden Markov model is used to take advantage of temporal context and estimate class probabilities conditioned on recent past history. In this hierarchical pattern of information flow, the time series data is transformed and mapped into a categorical representation (the fault classes) and integrated over time to enable robust decision-making.

  16. Hidden Markov models for fault detection in dynamic systems

    NASA Technical Reports Server (NTRS)

    Smyth, Padhraic J. (Inventor)

    1993-01-01

    The invention is a system failure monitoring method and apparatus which learns the symptom-fault mapping directly from training data. The invention first estimates the state of the system at discrete intervals in time. A feature vector x of dimension k is estimated from sets of successive windows of sensor data. A pattern recognition component then models the instantaneous estimate of the posterior class probability given the features, p(w(sub i) perpendicular to x), 1 less than or equal to i is less than or equal to m. Finally, a hidden Markov model is used to take advantage of temporal context and estimate class probabilities conditioned on recent past history. In this hierarchical pattern of information flow, the time series data is transformed and mapped into a categorical representation (the fault classes) and integrated over time to enable robust decision-making.

  17. Teager energy operator for multi-modulation extraction and its application for gearbox fault detection

    NASA Astrophysics Data System (ADS)

    Soltani Bozchalooi, I.; Liang, Ming

    2010-07-01

    This paper presents a parameter-free and broadband approach to detecting gear faults based on vibration signals. The technique is implemented using the Teager energy operator (TEO). It is shown that this operator can extract amplitude, phase and frequency modulations that are associated with various gear faults. Spectral analysis of the TEO-transformed signal provides the necessary information for fault detection. To improve the effectiveness of the proposed technique, we also devised a wavelet de-noising step based on online threshold estimation. In the de-noising step, the threshold estimation is performed through a frequency domain median absolute deviation (FMAD) scheme. The proposed fault detection technique is tested on simulated as well as experimental data acquired from a single-stage bevel gearbox and a two-stage parallel gearbox. US patent pending (serial number: 12/631,528).

  18. Fleet-Wide Prognostic and Health Management Suite: Asset Fault Signature Database

    SciTech Connect

    Vivek Agarwal; Nancy J. Lybeck; Randall Bickford; Richard Rusaw

    2015-06-01

    Proactive online monitoring in the nuclear industry is being explored using the Electric Power Research Institute’s Fleet-Wide Prognostic and Health Management (FW-PHM) Suite software. The FW-PHM Suite is a set of web-based diagnostic and prognostic tools and databases that serves as an integrated health monitoring architecture. The FW-PHM Suite has four main modules: (1) Diagnostic Advisor, (2) Asset Fault Signature (AFS) Database, (3) Remaining Useful Life Advisor, and (4) Remaining Useful Life Database. The paper focuses on the AFS Database of the FW-PHM Suite, which is used to catalog asset fault signatures. A fault signature is a structured representation of the information that an expert would use to first detect and then verify the occurrence of a specific type of fault. The fault signatures developed to assess the health status of generator step-up transformers are described in the paper. The developed fault signatures capture this knowledge and implement it in a standardized approach, thereby streamlining the diagnostic and prognostic process. This will support the automation of proactive online monitoring techniques in nuclear power plants to diagnose incipient faults, perform proactive maintenance, and estimate the remaining useful life of assets.

  19. An Integrated Approach for Aircraft Engine Performance Estimation and Fault Diagnostics

    NASA Technical Reports Server (NTRS)

    imon, Donald L.; Armstrong, Jeffrey B.

    2012-01-01

    A Kalman filter-based approach for integrated on-line aircraft engine performance estimation and gas path fault diagnostics is presented. This technique is specifically designed for underdetermined estimation problems where there are more unknown system parameters representing deterioration and faults than available sensor measurements. A previously developed methodology is applied to optimally design a Kalman filter to estimate a vector of tuning parameters, appropriately sized to enable estimation. The estimated tuning parameters can then be transformed into a larger vector of health parameters representing system performance deterioration and fault effects. The results of this study show that basing fault isolation decisions solely on the estimated health parameter vector does not provide ideal results. Furthermore, expanding the number of the health parameters to address additional gas path faults causes a decrease in the estimation accuracy of those health parameters representative of turbomachinery performance deterioration. However, improved fault isolation performance is demonstrated through direct analysis of the estimated tuning parameters produced by the Kalman filter. This was found to provide equivalent or superior accuracy compared to the conventional fault isolation approach based on the analysis of sensed engine outputs, while simplifying online implementation requirements. Results from the application of these techniques to an aircraft engine simulation are presented and discussed.

  20. Transformation Time

    ERIC Educational Resources Information Center

    Berry, John N., III

    2007-01-01

    The program for the march by librarians on America's capital for the American Library Association (ALA) conference is predictably loaded with lobbying, legislation, and DC tours. It also abounds with professional opportunity and reflects the impact of Leslie Burger, one of the most activist ALA presidents in recent history. Her "Transformation"…

  1. Transformation & Metamorphosis

    ERIC Educational Resources Information Center

    Lott, Debra

    2009-01-01

    The sculptures of Canadian artist Brian Jungen are a great inspiration for a lesson on creating new forms. Jungen transforms found objects into unique creations without fully concealing their original form or purpose. Frank Stella's sculpture series, including "K.132,2007" made of stainless steel and spray paint, is another great example of…

  2. Transforming Schools.

    ERIC Educational Resources Information Center

    Cookson, Peter W., Jr., Ed.; Schneider, Barbara, Ed.

    The authors in this book address the issues that relate to the crisis in American education and review some of the proposed solutions. To transform education, schools must be examined as social systems that are interrelated with families, communities, and the world of work. Following the introduction, section 1, "Conditions for Educational…

  3. Study of fault slip modes

    NASA Astrophysics Data System (ADS)

    Adushkin, V. V.; Kocharyan, G. G.; Novikov, V. A.

    2016-09-01

    We present the data of the laboratory experiments on studying the regularities of gradual transition from the stick-slip behavior to aseismic creeping on the interblock boundary. The experiments show that small variations in the material composition in the principal slip zones of the faults may cause a significant change in the fraction of seismic energy radiated during the dynamic unloading of the adjacent segment of the rock mass. The experiments simulate interblock sliding regimes with the values of the scaled kinetic energy differing by a few orders of magnitude and relatively small distinctions in the strength of the contacts and in the amplitude of the released shear stresses. The results of the experiments show that the slip mode and the fraction of the deformation energy that goes into the seismic radiation are determined by the ratio of two parameters—the stiffness of the fault and the stiffness of the enclosing rock mass. An important implication of the study for solving the engineering tasks is that for bringing a stressed segment of a fault or a crack into a slip mode with low-intensity radiation of seismic energy, the anthropogenic impact should be aimed at diminishing the stiffness of the fault zone rather than at releasing the excessive stresses.

  4. MOS integrated circuit fault modeling

    NASA Technical Reports Server (NTRS)

    Sievers, M.

    1985-01-01

    Three digital simulation techniques for MOS integrated circuit faults were examined. These techniques embody a hierarchy of complexity bracketing the range of simulation levels. The digital approaches are: transistor-level, connector-switch-attenuator level, and gate level. The advantages and disadvantages are discussed. Failure characteristics are also described.

  5. Tsunamis and splay fault dynamics

    USGS Publications Warehouse

    Wendt, J.; Oglesby, D.D.; Geist, E.L.

    2009-01-01

    The geometry of a fault system can have significant effects on tsunami generation, but most tsunami models to date have not investigated the dynamic processes that determine which path rupture will take in a complex fault system. To gain insight into this problem, we use the 3D finite element method to model the dynamics of a plate boundary/splay fault system. We use the resulting ground deformation as a time-dependent boundary condition for a 2D shallow-water hydrodynamic tsunami calculation. We find that if me stress distribution is homogeneous, rupture remains on the plate boundary thrust. When a barrier is introduced along the strike of the plate boundary thrust, rupture propagates to the splay faults, and produces a significantly larger tsunami man in the homogeneous case. The results have implications for the dynamics of megathrust earthquakes, and also suggest mat dynamic earthquake modeling may be a useful tool in tsunami researcn. Copyright 2009 by the American Geophysical Union.

  6. Cell boundary fault detection system

    DOEpatents

    Archer, Charles Jens; Pinnow, Kurt Walter; Ratterman, Joseph D.; Smith, Brian Edward

    2011-04-19

    An apparatus and program product determine a nodal fault along the boundary, or face, of a computing cell. Nodes on adjacent cell boundaries communicate with each other, and the communications are analyzed to determine if a node or connection is faulty.

  7. The Effect of Authigenic Phyllosilicate Growth on the Mechanical Behaviour of Upper Crustal Faults

    NASA Astrophysics Data System (ADS)

    Evans, S.; Holdsworth, R.; Imber, J.; Marco, S.; Weinberger, R.; De Paola, N.

    2014-12-01

    Deformation at shallow crustal depths is dominated by brittle processes, but it is increasingly recognised that diffusive mass transfer (DMT) processes and "ductile" folding also play a significant role in fault zone development. We present data from exhumed sections (<5 km depth) of the southern Dead Sea Fault System, Israel, an active continental transform fault that has accumulated 105 km of sinistral displacement since the Miocene. The faults juxtapose various wall rock lithologies (crystalline basement, carbonate and clastic cover), but the studied sections all have phyllosilicate-rich fault cores. Damage zones show a range of deformation mechanisms including pulverisation, pressure-solution and cataclasis. Our results show that fault cores comprise three distinct types of fault gouge (alongside coarser-grained cataclasite): cataclastic gouge that is mineralogically similar to wall rock compositions; authigenic gouge that is dominated by Mg-rich smectite not present in adjacent formations; and mechanically entrained, folded shale gouge that is almost identical in mineralogy to a local shale protolith. Microstructural observations suggest authigenic gouge is the result of DMT processes, following an earlier phase of gouge formation through microfracturing and cataclasis. The low abundance of carbonate within fault cores suggests its dissolution is a contributing factor in authigenic smectite precipitation. Such mineralogical transformations may lead to significant changes in the frictional properties of fault zones, from materials of relatively high frictional strength (quartz, feldspars, dolomite, where μ = 0.6 - 0.85) to those with much lower frictional strengths, such as smectite (where μ can be as low as 0.15). We demonstrate how the physical properties of faults may evolve over time when conditions allow precipitation of weak-phases in addition to brittle deformation, which may facilitate ingress of fluid into fault cores and enhance phyllosilicate

  8. Fault-related clay authigenesis along the Moab Fault: Implications for calculations of fault rock composition and mechanical and hydrologic fault zone properties

    USGS Publications Warehouse

    Solum, J.G.; Davatzes, N.C.; Lockner, D.A.

    2010-01-01

    The presence of clays in fault rocks influences both the mechanical and hydrologic properties of clay-bearing faults, and therefore it is critical to understand the origin of clays in fault rocks and their distributions is of great importance for defining fundamental properties of faults in the shallow crust. Field mapping shows that layers of clay gouge and shale smear are common along the Moab Fault, from exposures with throws ranging from 10 to ???1000 m. Elemental analyses of four locations along the Moab Fault show that fault rocks are enriched in clays at R191 and Bartlett Wash, but that this clay enrichment occurred at different times and was associated with different fluids. Fault rocks at Corral and Courthouse Canyons show little difference in elemental composition from adjacent protolith, suggesting that formation of fault rocks at those locations is governed by mechanical processes. Friction tests show that these authigenic clays result in fault zone weakening, and potentially influence the style of failure along the fault (seismogenic vs. aseismic) and potentially influence the amount of fluid loss associated with coseismic dilation. Scanning electron microscopy shows that authigenesis promotes that continuity of slip surfaces, thereby enhancing seal capacity. The occurrence of the authigenesis, and its influence on the sealing properties of faults, highlights the importance of determining the processes that control this phenomenon. ?? 2010 Elsevier Ltd.

  9. Fault-related clay authigenesis along the Moab Fault: Implications for calculations of fault rock composition and mechanical and hydrologic fault zone properties

    NASA Astrophysics Data System (ADS)

    Solum, John G.; Davatzes, Nicholas C.; Lockner, David A.

    2010-12-01

    The presence of clays in fault rocks influences both the mechanical and hydrologic properties of clay-bearing faults, and therefore it is critical to understand the origin of clays in fault rocks and their distributions is of great importance for defining fundamental properties of faults in the shallow crust. Field mapping shows that layers of clay gouge and shale smear are common along the Moab Fault, from exposures with throws ranging from 10 to ˜1000 m. Elemental analyses of four locations along the Moab Fault show that fault rocks are enriched in clays at R191 and Bartlett Wash, but that this clay enrichment occurred at different times and was associated with different fluids. Fault rocks at Corral and Courthouse Canyons show little difference in elemental composition from adjacent protolith, suggesting that formation of fault rocks at those locations is governed by mechanical processes. Friction tests show that these authigenic clays result in fault zone weakening, and potentially influence the style of failure along the fault (seismogenic vs. aseismic) and potentially influence the amount of fluid loss associated with coseismic dilation. Scanning electron microscopy shows that authigenesis promotes that continuity of slip surfaces, thereby enhancing seal capacity. The occurrence of the authigenesis, and its influence on the sealing properties of faults, highlights the importance of determining the processes that control this phenomenon.

  10. 5 CFR 831.1402 - Fault.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 5 Administrative Personnel 2 2010-01-01 2010-01-01 false Fault. 831.1402 Section 831.1402...) RETIREMENT Standards for Waiver of Overpayments § 831.1402 Fault. A recipient of an overpayment is without fault if he/she performed no act of commission or omission which resulted in the overpayment. The...

  11. 5 CFR 845.302 - Fault.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 5 Administrative Personnel 2 2014-01-01 2014-01-01 false Fault. 845.302 Section 845.302... EMPLOYEES RETIREMENT SYSTEM-DEBT COLLECTION Standards for Waiver of Overpayments § 845.302 Fault. A recipient of an overpayment is without fault if he or she performed no act of commission or omission...

  12. 5 CFR 845.302 - Fault.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 5 Administrative Personnel 2 2010-01-01 2010-01-01 false Fault. 845.302 Section 845.302... EMPLOYEES RETIREMENT SYSTEM-DEBT COLLECTION Standards for Waiver of Overpayments § 845.302 Fault. A recipient of an overpayment is without fault if he or she performed no act of commission or omission...

  13. 5 CFR 845.302 - Fault.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 5 Administrative Personnel 2 2012-01-01 2012-01-01 false Fault. 845.302 Section 845.302... EMPLOYEES RETIREMENT SYSTEM-DEBT COLLECTION Standards for Waiver of Overpayments § 845.302 Fault. A recipient of an overpayment is without fault if he or she performed no act of commission or omission...

  14. 40 CFR 258.13 - Fault areas.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Fault areas. 258.13 Section 258.13... SOLID WASTE LANDFILLS Location Restrictions § 258.13 Fault areas. (a) New MSWLF units and lateral expansions shall not be located within 200 feet (60 meters) of a fault that has had displacement in...

  15. 5 CFR 831.1402 - Fault.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 5 Administrative Personnel 2 2012-01-01 2012-01-01 false Fault. 831.1402 Section 831.1402...) RETIREMENT Standards for Waiver of Overpayments § 831.1402 Fault. A recipient of an overpayment is without fault if he/she performed no act of commission or omission which resulted in the overpayment. The...

  16. 5 CFR 845.302 - Fault.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 5 Administrative Personnel 2 2013-01-01 2013-01-01 false Fault. 845.302 Section 845.302... EMPLOYEES RETIREMENT SYSTEM-DEBT COLLECTION Standards for Waiver of Overpayments § 845.302 Fault. A recipient of an overpayment is without fault if he or she performed no act of commission or omission...

  17. 5 CFR 845.302 - Fault.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 5 Administrative Personnel 2 2011-01-01 2011-01-01 false Fault. 845.302 Section 845.302... EMPLOYEES RETIREMENT SYSTEM-DEBT COLLECTION Standards for Waiver of Overpayments § 845.302 Fault. A recipient of an overpayment is without fault if he or she performed no act of commission or omission...

  18. 5 CFR 831.1402 - Fault.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 5 Administrative Personnel 2 2013-01-01 2013-01-01 false Fault. 831.1402 Section 831.1402...) RETIREMENT Standards for Waiver of Overpayments § 831.1402 Fault. A recipient of an overpayment is without fault if he/she performed no act of commission or omission which resulted in the overpayment. The...

  19. High temperature superconducting fault current limiter

    DOEpatents

    Hull, John R.

    1997-01-01

    A fault current limiter (10) for an electrical circuit (14). The fault current limiter (10) includes a high temperature superconductor (12) in the electrical circuit (14). The high temperature superconductor (12) is cooled below its critical temperature to maintain the superconducting electrical properties during operation as the fault current limiter (10).

  20. 20 CFR 255.11 - Fault.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 20 Employees' Benefits 1 2013-04-01 2012-04-01 true Fault. 255.11 Section 255.11 Employees... § 255.11 Fault. (a) Before recovery of an overpayment may be waived, it must be determined that the overpaid individual was without fault in causing the overpayment. If recovery is sought from other than...

  1. High temperature superconducting fault current limiter

    DOEpatents

    Hull, J.R.

    1997-02-04

    A fault current limiter for an electrical circuit is disclosed. The fault current limiter includes a high temperature superconductor in the electrical circuit. The high temperature superconductor is cooled below its critical temperature to maintain the superconducting electrical properties during operation as the fault current limiter. 15 figs.

  2. 40 CFR 258.13 - Fault areas.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Fault areas. 258.13 Section 258.13... SOLID WASTE LANDFILLS Location Restrictions § 258.13 Fault areas. (a) New MSWLF units and lateral expansions shall not be located within 200 feet (60 meters) of a fault that has had displacement in...

  3. 5 CFR 831.1402 - Fault.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 5 Administrative Personnel 2 2014-01-01 2014-01-01 false Fault. 831.1402 Section 831.1402...) RETIREMENT Standards for Waiver of Overpayments § 831.1402 Fault. A recipient of an overpayment is without fault if he/she performed no act of commission or omission which resulted in the overpayment. The...

  4. 40 CFR 258.13 - Fault areas.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Fault areas. 258.13 Section 258.13... SOLID WASTE LANDFILLS Location Restrictions § 258.13 Fault areas. (a) New MSWLF units and lateral expansions shall not be located within 200 feet (60 meters) of a fault that has had displacement in...

  5. 40 CFR 258.13 - Fault areas.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 26 2012-07-01 2011-07-01 true Fault areas. 258.13 Section 258.13... SOLID WASTE LANDFILLS Location Restrictions § 258.13 Fault areas. (a) New MSWLF units and lateral expansions shall not be located within 200 feet (60 meters) of a fault that has had displacement in...

  6. 20 CFR 255.11 - Fault.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 1 2012-04-01 2012-04-01 false Fault. 255.11 Section 255.11 Employees... § 255.11 Fault. (a) Before recovery of an overpayment may be waived, it must be determined that the overpaid individual was without fault in causing the overpayment. If recovery is sought from other than...

  7. 5 CFR 831.1402 - Fault.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 5 Administrative Personnel 2 2011-01-01 2011-01-01 false Fault. 831.1402 Section 831.1402...) RETIREMENT Standards for Waiver of Overpayments § 831.1402 Fault. A recipient of an overpayment is without fault if he/she performed no act of commission or omission which resulted in the overpayment. The...

  8. 20 CFR 255.11 - Fault.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 1 2014-04-01 2012-04-01 true Fault. 255.11 Section 255.11 Employees... § 255.11 Fault. (a) Before recovery of an overpayment may be waived, it must be determined that the overpaid individual was without fault in causing the overpayment. If recovery is sought from other than...

  9. Architecture of small-scale fault zones in the context of the Leinetalgraben Fault System

    NASA Astrophysics Data System (ADS)

    Reyer, Dorothea; Philipp, Sonja L.

    2010-05-01

    Understanding fault zone properties in different geological settings is important to better assess the development and propagation of faults. In addition this allows better evaluation and permeability estimates of potential fault-related geothermal reservoirs. The Leinetalgraben fault system provides an outcrop analogue for many fault zones in the subsurface of the North German Basin. The Leinetalgraben is a N-S-trending graben structure, initiated in the Jurassic, in the south of Lower Saxony and as such part of the North German Basin. The fault system was reactivated and inverted during Alpine compression in the Tertiary. This complex geological situation was further affected by halotectonics. Therefore we can find different types of fault zones, that is normal, reverse, strike-slip an oblique-slip faults, surrounding the major Leinetalgraben boundary faults. Here we present first results of structural geological field studies on the geometry and architecture of fault zones in the Leinetalgraben Fault System in outcrop-scale. We measured the orientations and displacements of 17 m-scale fault zones in limestone (Muschelkalk) outcrops, the thicknesses of their fault cores and damage zones, as well as the fracture densities and geometric parameters of the fracture systems therein. We also analysed the effects of rock heterogeneities, particularly stiffness variations between layers (mechanical layering) on the propagation of natural fractures and fault zones. The analysed fault zones predominantly show similar orientations as the major fault zones they surround. Other faults are conjugate or perpendicular to the major fault zones. The direction of predominant joint strike corresponds to the orientation of the fault zones in the majority of cases. The mechanical layering of the limestone and marlstone stratification obviously has great effects on fracture propagation. Already thin layers (mm- to cm-scale) of low stiffness - here marl - seem to suffice to change the

  10. Fault-crossing P delays, epicentral biasing, and fault behavior in Central California

    USGS Publications Warehouse

    Marks, S.M.; Bufe, C.G.

    1979-01-01

    The P delays across the San Andreas fault zone in central California have been determined from travel-time differences at station pairs spanning the fault, using off-fault local earthquake or quarry blast sources. Systematic delays as large as 0.4 sec have been observed for paths crossing the fault at depths of 5-10 km. These delays can account for the apparent deviation of epicenters from the mapped fault trace. The largest delays occur along the San Andreas fault between San Juan Bautista and Bear Valley and Between Bitterwater Valley and Parkfield. Spatial variations in fault behavior correlate with the magnitude of the fault-crossing P delay. The delay decreases to the northwest of San Juan Bautista across the "locked" section of the San Andreas fault and also decreases to the southeast approaching Parkfield. Where the delay is large, seismicity is relatively high and the fault is creeping. ?? 1979.

  11. Improved CICA algorithm used for single channel compound fault diagnosis of rolling bearings

    NASA Astrophysics Data System (ADS)

    Chen, Guohua; Qie, Longfei; Zhang, Aijun; Han, Jin

    2016-01-01

    A Compound fault signal usually contains multiple characteristic signals and strong confusion noise, which makes it difficult to separate week fault signals from them through conventional ways, such as FFT-based envelope detection, wavelet transform or empirical mode decomposition individually. In order to realize single channel compound fault diagnosis of bearings and improve the diagnosis accuracy, an improved CICA algorithm named constrained independent component analysis based on the energy method (E-CICA) is proposed. With the approach, the single channel vibration signal is firstly decomposed into several wavelet coefficients by discrete wavelet transform(DWT) method for the purpose of obtaining multichannel signals. Then the envelope signals of the reconstructed wavelet coefficients are selected as the input of E-CICA algorithm, which fulfills the requirements that the number of sensors is greater than or equal to that of the source signals and makes it more suitable to be processed by CICA strategy. The frequency energy ratio(ER) of each wavelet reconstructed signal to the total energy of the given synchronous signal is calculated, and then the synchronous signal with maximum ER value is set as the reference signal accordingly. By this way, the reference signal contains a priori knowledge of fault source signal and the influence on fault signal extraction accuracy which is caused by the initial phase angle and the duty ratio of the reference signal in the traditional CICA algorithm is avoided. Experimental results show that E-CICA algorithm can effectively separate out the outer-race defect and the rollers defect from the single channel compound fault and fulfill the needs of compound fault diagnosis of rolling bearings, and the running time is 0.12% of that of the traditional CICA algorithm and the extraction accuracy is 1.4 times of that of CICA as well. The proposed research provides a new method to separate single channel compound fault signals.

  12. Fault Diagnosis in HVAC Chillers

    NASA Technical Reports Server (NTRS)

    Choi, Kihoon; Namuru, Setu M.; Azam, Mohammad S.; Luo, Jianhui; Pattipati, Krishna R.; Patterson-Hine, Ann

    2005-01-01

    Modern buildings are being equipped with increasingly sophisticated power and control systems with substantial capabilities for monitoring and controlling the amenities. Operational problems associated with heating, ventilation, and air-conditioning (HVAC) systems plague many commercial buildings, often the result of degraded equipment, failed sensors, improper installation, poor maintenance, and improperly implemented controls. Most existing HVAC fault-diagnostic schemes are based on analytical models and knowledge bases. These schemes are adequate for generic systems. However, real-world systems significantly differ from the generic ones and necessitate modifications of the models and/or customization of the standard knowledge bases, which can be labor intensive. Data-driven techniques for fault detection and isolation (FDI) have a close relationship with pattern recognition, wherein one seeks to categorize the input-output data into normal or faulty classes. Owing to the simplicity and adaptability, customization of a data-driven FDI approach does not require in-depth knowledge of the HVAC system. It enables the building system operators to improve energy efficiency and maintain the desired comfort level at a reduced cost. In this article, we consider a data-driven approach for FDI of chillers in HVAC systems. To diagnose the faults of interest in the chiller, we employ multiway dynamic principal component analysis (MPCA), multiway partial least squares (MPLS), and support vector machines (SVMs). The simulation of a chiller under various fault conditions is conducted using a standard chiller simulator from the American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE). We validated our FDI scheme using experimental data obtained from different types of chiller faults.

  13. Fault tolerant control of spacecraft

    NASA Astrophysics Data System (ADS)

    Godard

    Autonomous multiple spacecraft formation flying space missions demand the development of reliable control systems to ensure rapid, accurate, and effective response to various attitude and formation reconfiguration commands. Keeping in mind the complexities involved in the technology development to enable spacecraft formation flying, this thesis presents the development and validation of a fault tolerant control algorithm that augments the AOCS on-board a spacecraft to ensure that these challenging formation flying missions will fly successfully. Taking inspiration from the existing theory of nonlinear control, a fault-tolerant control system for the RyePicoSat missions is designed to cope with actuator faults whilst maintaining the desirable degree of overall stability and performance. Autonomous fault tolerant adaptive control scheme for spacecraft equipped with redundant actuators and robust control of spacecraft in underactuated configuration, represent the two central themes of this thesis. The developed algorithms are validated using a hardware-in-the-loop simulation. A reaction wheel testbed is used to validate the proposed fault tolerant attitude control scheme. A spacecraft formation flying experimental testbed is used to verify the performance of the proposed robust control scheme for underactuated spacecraft configurations. The proposed underactuated formation flying concept leads to more than 60% savings in fuel consumption when compared to a fully actuated spacecraft formation configuration. We also developed a novel attitude control methodology that requires only a single thruster to stabilize three axis attitude and angular velocity components of a spacecraft. Numerical simulations and hardware-in-the-loop experimental results along with rigorous analytical stability analysis shows that the proposed methodology will greatly enhance the reliability of the spacecraft, while allowing for potentially significant overall mission cost reduction.

  14. Fault-Tolerant Heat Exchanger

    NASA Technical Reports Server (NTRS)

    Izenson, Michael G.; Crowley, Christopher J.

    2005-01-01

    A compact, lightweight heat exchanger has been designed to be fault-tolerant in the sense that a single-point leak would not cause mixing of heat-transfer fluids. This particular heat exchanger is intended to be part of the temperature-regulation system for habitable modules of the International Space Station and to function with water and ammonia as the heat-transfer fluids. The basic fault-tolerant design is adaptable to other heat-transfer fluids and heat exchangers for applications in which mixing of heat-transfer fluids would pose toxic, explosive, or other hazards: Examples could include fuel/air heat exchangers for thermal management on aircraft, process heat exchangers in the cryogenic industry, and heat exchangers used in chemical processing. The reason this heat exchanger can tolerate a single-point leak is that the heat-transfer fluids are everywhere separated by a vented volume and at least two seals. The combination of fault tolerance, compactness, and light weight is implemented in a unique heat-exchanger core configuration: Each fluid passage is entirely surrounded by a vented region bridged by solid structures through which heat is conducted between the fluids. Precise, proprietary fabrication techniques make it possible to manufacture the vented regions and heat-conducting structures with very small dimensions to obtain a very large coefficient of heat transfer between the two fluids. A large heat-transfer coefficient favors compact design by making it possible to use a relatively small core for a given heat-transfer rate. Calculations and experiments have shown that in most respects, the fault-tolerant heat exchanger can be expected to equal or exceed the performance of the non-fault-tolerant heat exchanger that it is intended to supplant (see table). The only significant disadvantages are a slight weight penalty and a small decrease in the mass-specific heat transfer.

  15. Recurrent late Quaternary surface faulting along the southern Mohawk Valley fault zone, NE California

    SciTech Connect

    Sawyer, T.L.; Hemphill-Haley, M.A. ); Page, W.D. )

    1993-04-01

    The Mohawk Valley fault zone comprises NW- to NNW-striking, normal and strike-slip( ) faults that form the western edge of the Plumas province, a diffuse transitional zone between the Basin and Range and the northern Sierra Nevada. The authors detailed evaluation of the southern part of the fault zone reveals evidence for recurrent late Pleistocene to possibly Holocene, moderate to large surface-faulting events. The southern Mohawk fault zone is a complex, 6-km-wide zone of faults and related features that extends from near the crest of the Sierra Nevada to the middle of southern Sierra Valley. The fault zone has two distinct and generally parallel subzones, 3 km apart, that are delineated by markedly different geomorphic characteristics and apparently different styles of faulting. Paleoseismic activity of the western subzone was evaluated in two trenches: one across a fault antithetic to the main range-bounding fault, and the other across a splay fault delineated by a 3.7-m-high scarp in alluvium. Stratigraphic relations, soil development, and radiocarbon dates indicate that at least four mid- to late-Pleistocene surface-faulting events, having single-event displacements in excess of 1.6 to 2.6 m, occurred along the splay fault prior to 12 ka. The antithetic fault has evidence of three late Pleistocene events that may correspond to event documented on the splay fault, and a Holocene event that is inferred from youthful scarplets and small closed depressions.

  16. Novel neural networks-based fault tolerant control scheme with fault alarm.

    PubMed

    Shen, Qikun; Jiang, Bin; Shi, Peng; Lim, Cheng-Chew

    2014-11-01

    In this paper, the problem of adaptive active fault-tolerant control for a class of nonlinear systems with unknown actuator fault is investigated. The actuator fault is assumed to have no traditional affine appearance of the system state variables and control input. The useful property of the basis function of the radial basis function neural network (NN), which will be used in the design of the fault tolerant controller, is explored. Based on the analysis of the design of normal and passive fault tolerant controllers, by using the implicit function theorem, a novel NN-based active fault-tolerant control scheme with fault alarm is proposed. Comparing with results in the literature, the fault-tolerant control scheme can minimize the time delay between fault occurrence and accommodation that is called the time delay due to fault diagnosis, and reduce the adverse effect on system performance. In addition, the FTC scheme has the advantages of a passive fault-tolerant control scheme as well as the traditional active fault-tolerant control scheme's properties. Furthermore, the fault-tolerant control scheme requires no additional fault detection and isolation model which is necessary in the traditional active fault-tolerant control scheme. Finally, simulation results are presented to demonstrate the efficiency of the developed techniques.

  17. The Depth of Detachment Faulting at Mid-Ocean Ridges : Evidence From Zircon Geo- and Thermochronometry

    NASA Astrophysics Data System (ADS)

    Grimes, C. B.; John, B. E.; Cheadle, M. J.; Reiners, P. W.; Wooden, J. L.

    2008-12-01

    Pb/U and (U-Th)/He zircon ages determined from evolved samples of gabbroic crust exposed in the footwalls of large-offset, low-angle normal faults near the Atlantis and Fifteen-Twenty Transforms on the Mid-Atlantic Ridge (MAR; ODP Holes 1275D and 1270D, IODP Hole U1309D), provide new constraints on the depth of detachment faulting at mid-ocean ridges. Ti-in-zircon crystallization temperatures, taken with the closure temperature of the (U-Th)/He system in zircon bracket the acquisition temperature of magnetic remanence; collectively these three chronometers define a cooling history for footwall gabbro sections over the temperature range of ~900°-220° C. Time-averaged cooling rates over 900°- 220° C from all holes investigated range from 1025(+645, -330)° C/m.y. to 2110(+1600, -720)° C/m.y. Assuming the gabbroic footwall was denuded along a single, continuous fault system, the time interval defined by the difference in Pb/U and (U-Th)/He ages for zircon from rocks beneath the fault can be used to estimate the distance between the 900° and 200° C isotherms along the fault system, and therefore the length-scale of the fault system while it was active, if the fault slip rate is known. As these large-offset faults serve as the plate boundary, the fault slip rate is equivalent to the plate-spreading rate during formation of the footwall. During formation of the Atlantis Massif core complex (30° N, MAR), accretion was asymmetric, with spreading partitioned on the North American plate at a rate approaching the full spreading rate of 24 mm/yr. This rate, along with a cooling time interval of 0.42±0.09 Ma implies that a single, continuous fault system would have had a length of 10±2.3 km between the 900° and 200° C isotherms while active. Lengths of fault systems determined at ODP Holes 1275D and 1270D are 9.5±3.2 km and 5.0±2.9 km, respectively, assuming a fault slip rate equivalent to 65% of the full plate spreading rate (consistent with asymmetric accretion

  18. A High shear stress segment along the San Andreas Fault: Inferences based on near-field stress direction and stress magnitude observations in the Carrizo Plain Area

    SciTech Connect

    Castillo, D. A.,; Younker, L.W.

    1997-01-30

    Nearly 200 new in-situ determinations of stress directions and stress magnitudes near the Carrizo plain segment of the San Andreas fault indicate a marked change in stress state occurring within 20 km of this principal transform plate boundary. A natural consequence of this stress transition is that if the observed near-field ``fault-oblique`` stress directions are representative of the fault stress state, the Mohr-Coulomb shear stresses resolved on San Andreas sub-parallel planes are substantially greater than previously inferred based on fault-normal compression. Although the directional stress data and near-hydrostatic pore pressures, which exist within 15 km of the fault, support a high shear stress environment near the fault, appealing to elevated pore pressures in the fault zone (Byerlee-Rice Model) merely enhances the likelihood of shear failure. These near-field stress observations raise important questions regarding what previous stress observations have actually been measuring. The ``fault-normal`` stress direction measured out to 70 km from the fault can be interpreted as representing a comparable depth average shear strength of the principal plate boundary. Stress measurements closer to the fault reflect a shallower depth-average representation of the fault zone shear strength. If this is true, only stress observations at fault distances comparable to the seismogenic depth will be representative of the fault zone shear strength. This is consistent with results from dislocation monitoring where there is pronounced shear stress accumulation out to 20 km of the fault as a result of aseismic slip within the lower crust loading the upper locked section. Beyond about 20 km, the shear stress resolved on San Andreas fault-parallel planes becomes negligible. 65 refs., 15 figs.

  19. Multiple Fault Isolation in Redundant Systems

    NASA Technical Reports Server (NTRS)

    Pattipati, Krishna R.; Patterson-Hine, Ann; Iverson, David

    1997-01-01

    Fault diagnosis in large-scale systems that are products of modern technology present formidable challenges to manufacturers and users. This is due to large number of failure sources in such systems and the need to quickly isolate and rectify failures with minimal down time. In addition, for fault-tolerant systems and systems with infrequent opportunity for maintenance (e.g., Hubble telescope, space station), the assumption of at most a single fault in the system is unrealistic. In this project, we have developed novel block and sequential diagnostic strategies to isolate multiple faults in the shortest possible time without making the unrealistic single fault assumption.

  20. Multiple Fault Isolation in Redundant Systems

    NASA Technical Reports Server (NTRS)

    Pattipati, Krishna R.

    1997-01-01

    Fault diagnosis in large-scale systems that are products of modem technology present formidable challenges to manufacturers and users. This is due to large number of failure sources in such systems and the need to quickly isolate and rectify failures with minimal down time. In addition, for fault-tolerant systems and systems with infrequent opportunity for maintenance (e.g., Hubble telescope, space station), the assumption of at most a single fault in the system is unrealistic. In this project, we have developed novel block and sequential diagnostic strategies to isolate multiple faults in the shortest possible time without making the unrealistic single fault assumption.

  1. Deformation associated with continental normal faults

    NASA Astrophysics Data System (ADS)

    Resor, Phillip G.

    Deformation associated with normal fault earthquakes and geologic structures provide insights into the seismic cycle as it unfolds over time scales from seconds to millions of years. Improved understanding of normal faulting will lead to more accurate seismic hazard assessments and prediction of associated structures. High-precision aftershock locations for the 1995 Kozani-Grevena earthquake (Mw 6.5), Greece image a segmented master fault and antithetic faults. This three-dimensional fault geometry is typical of normal fault systems mapped from outcrop or interpreted from reflection seismic data and illustrates the importance of incorporating three-dimensional fault geometry in mechanical models. Subsurface fault slip associated with the Kozani-Grevena and 1999 Hector Mine (Mw 7.1) earthquakes is modeled using a new method for slip inversion on three-dimensional fault surfaces. Incorporation of three-dimensional fault geometry improves the fit to the geodetic data while honoring aftershock distributions and surface ruptures. GPS Surveying of deformed bedding surfaces associated with normal faulting in the western Grand Canyon reveals patterns of deformation that are similar to those observed by interferometric satellite radar interferometry (InSAR) for the Kozani Grevena earthquake with a prominent down-warp in the hanging wall and a lesser up-warp in the footwall. However, deformation associated with the Kozani-Grevena earthquake extends ˜20 km from the fault surface trace, while the folds in the western Grand Canyon only extend 500 m into the footwall and 1500 m into the hanging wall. A comparison of mechanical and kinematic models illustrates advantages of mechanical models in exploring normal faulting processes including incorporation of both deformation and causative forces, and the opportunity to incorporate more complex fault geometry and constitutive properties. Elastic models with antithetic or synthetic faults or joints in association with a master

  2. Managing Space System Faults: Coalescing NASA's Views

    NASA Technical Reports Server (NTRS)

    Muirhead, Brian; Fesq, Lorraine

    2012-01-01

    Managing faults and their resultant failures is a fundamental and critical part of developing and operating aerospace systems. Yet, recent studies have shown that the engineering "discipline" required to manage faults is not widely recognized nor evenly practiced within the NASA community. Attempts to simply name this discipline in recent years has been fraught with controversy among members of the Integrated Systems Health Management (ISHM), Fault Management (FM), Fault Protection (FP), Hazard Analysis (HA), and Aborts communities. Approaches to managing space system faults typically are unique to each organization, with little commonality in the architectures, processes and practices across the industry.

  3. RF transformer

    DOEpatents

    Smith, James L.; Helenberg, Harold W.; Kilsdonk, Dennis J.

    1979-01-01

    There is provided an improved RF transformer having a single-turn secondary of cylindrical shape and a coiled encapsulated primary contained within the secondary. The coil is tapered so that the narrowest separation between the primary and the secondary is at one end of the coil. The encapsulated primary is removable from the secondary so that a variety of different capacity primaries can be utilized with one secondary.

  4. Case for very low coupling stress on the Cascadia Ssubduction Fault

    NASA Astrophysics Data System (ADS)

    Wang, Kelin; Mulder, Taimi; Rogers, Garry C.; Hyndman, Roy D.

    1995-07-01

    A fundamental problem in plate tectonics is the shear strength of major plate boundary faults. This translates to the question whether the generally observed small earthquake stress drops of 3-10 MPa on major faults release most of the accumulated stress or only a small fraction of it. There is strong evidence that the San Andreas fault, a major transform plate boundary, is weak (<20 MPa shear resistance). It is not yet clear whether subduction thrust faults are also weak. We present two types of evidence from the northern Cascadia subduction zone that indicate very low coupling shear stress on that plate interface and hence very low strength of the subduction thrust fault, comparable to that estimated for the San Andreas fault. First, the well-defined surface heat flow and heat generation allow negligible frictional heating on the plate interface. The average shear stress on the fault must thus be very low over a time scale of a few million years. Second, focal mechanism solutions for small crustal earthquakes in the southern Vancouver Island area indicate that the horizontal stress in the direction of plate convergence has a similar magnitude to the vertical stress. This inferred stress state requires the present tectonic stress coupled across the subduction thrust fault to be very low. One explanation for the weakness of the fault is the presence of near-lithostatic pore fluid pressure in the region of the fault zone for which there is independent evidence. The conclusion of a weak subduction thrust fault does not conflict with geodetic observations of contemporary surface deformation which indicate that the fault is currently locked, accumulating strain energy toward a future great earthquake. The surface deformation responds to the small (<20 MPa) temporal changes of the stress field associated with the subduction earthquake cycle. This transient stress is superimposed on the larger background regional stress field in which the maximum compression is parallel

  5. Frictional constraints on crustal faulting

    USGS Publications Warehouse

    Boatwright, J.; Cocco, M.

    1996-01-01

    We consider how variations in fault frictional properties affect the phenomenology of earthquake faulting. In particular, we propose that lateral variations in fault friction produce the marked heterogeneity of slip observed in large earthquakes. We model these variations using a rate- and state-dependent friction law, where we differentiate velocity-weakening behavior into two fields: the strong seismic field is very velocity weakening and the weak seismic field is slightly velocity weakening. Similarly, we differentiate velocity-strengthening behavior into two fields: the compliant field is slightly velocity strengthening and the viscous field is very velocity strengthening. The strong seismic field comprises the seismic slip concentrations, or asperities. The two "intermediate" fields, weak seismic and compliant, have frictional velocity dependences that are close to velocity neutral: these fields modulate both the tectonic loading and the dynamic rupture process. During the interseismic period, the weak seismic and compliant regions slip aseismically, while the strong seismic regions remain locked, evolving into stress concentrations that fail only in main shocks. The weak seismic areas exhibit most of the interseismic activity and aftershocks but can also creep seismically. This "mixed" frictional behavior can be obtained from a sufficiently heterogenous distribution of the critical slip distance. The model also provides a mechanism for rupture arrest: dynamic rupture fronts decelerate as they penetrate into unloaded complaint or weak seismic areas, producing broad areas of accelerated afterslip. Aftershocks occur on both the weak seismic and compliant areas around a fault, but most of the stress is diffused through aseismic slip. Rapid afterslip on these peripheral areas can also produce aftershocks within the main shock rupture area by reloading weak fault areas that slipped in the main shock and then healed. We test this frictional model by comparing the

  6. Silica Lubrication in Faults (Invited)

    NASA Astrophysics Data System (ADS)

    Rowe, C. D.; Rempe, M.; Lamothe, K.; Kirkpatrick, J. D.; White, J. C.; Mitchell, T. M.; Andrews, M.; Di Toro, G.

    2013-12-01

    Silica-rich rocks are common in the crust, so silica lubrication may be important for causing fault weakening during earthquakes if the phenomenon occurs in nature. In laboratory friction experiments on chert, dramatic shear weakening has been attributed to amorphization and attraction of water from atmospheric humidity to form a 'silica gel'. Few observations of the slip surfaces have been reported, and the details of weakening mechanism(s) remain enigmatic. Therefore, no criteria exist on which to make comparisons of experimental materials to natural faults. We performed a series of friction experiments, characterized the materials formed on the sliding surface, and compared these to a geological fault in the same rock type. Experiments were performed in the presence of room humidity at 2.5 MPa normal stress with 3 and 30 m total displacement for a variety of slip rates (10-4 - 10-1 m/s). The friction coefficient (μ) reduced from >0.6 to ~0.2 at 10-1 m/s, but only fell to ~0.4 at 10-2 - 10-4 m/s. The slip surfaces and wear material were observed using laser confocal Raman microscopy, electron microprobe, X-ray diffraction, and transmission electron microscopy. Experiments at 10-1 m/s formed wear material consisting of ≤1 μm powder that is aggregated into irregular 5-20 μm clumps. Some material disaggregated during analysis with electron beams and lasers, suggesting hydrous and unstable components. Compressed powder forms smooth pavements on the surface in which grains are not visible (if present, they are <100 nm). Powder contains amorphous material and as yet unidentified crystalline and non-crystalline forms of silica (not quartz), while the worn chert surface underneath shows Raman spectra consistent with a mixture of quartz and amorphous material. If silica amorphization facilitates shear weakening in natural faults, similar wear materials should be formed, and we may be able to identify them through microstructural studies. However, the sub

  7. Model-Based Fault Tolerant Control

    NASA Technical Reports Server (NTRS)

    Kumar, Aditya; Viassolo, Daniel

    2008-01-01

    The Model Based Fault Tolerant Control (MBFTC) task was conducted under the NASA Aviation Safety and Security Program. The goal of MBFTC is to develop and demonstrate real-time strategies to diagnose and accommodate anomalous aircraft engine events such as sensor faults, actuator faults, or turbine gas-path component damage that can lead to in-flight shutdowns, aborted take offs, asymmetric thrust/loss of thrust control, or engine surge/stall events. A suite of model-based fault detection algorithms were developed and evaluated. Based on the performance and maturity of the developed algorithms two approaches were selected for further analysis: (i) multiple-hypothesis testing, and (ii) neural networks; both used residuals from an Extended Kalman Filter to detect the occurrence of the selected faults. A simple fusion algorithm was implemented to combine the results from each algorithm to obtain an overall estimate of the identified fault type and magnitude. The identification of the fault type and magnitude enabled the use of an online fault accommodation strategy to correct for the adverse impact of these faults on engine operability thereby enabling continued engine operation in the presence of these faults. The performance of the fault detection and accommodation algorithm was extensively tested in a simulation environment.

  8. Tool for Viewing Faults Under Terrain

    NASA Technical Reports Server (NTRS)

    Siegel, Herbert, L.; Li, P. Peggy

    2005-01-01

    Multi Surface Light Table (MSLT) is an interactive software tool that was developed in support of the QuakeSim project, which has created an earthquake- fault database and a set of earthquake- simulation software tools. MSLT visualizes the three-dimensional geometries of faults embedded below the terrain and animates time-varying simulations of stress and slip. The fault segments, represented as rectangular surfaces at dip angles, are organized into collections, that is, faults. An interface built into MSLT queries and retrieves fault definitions from the QuakeSim fault database. MSLT also reads time-varying output from one of the QuakeSim simulation tools, called "Virtual California." Stress intensity is represented by variations in color. Slips are represented by directional indicators on the fault segments. The magnitudes of the slips are represented by the duration of the directional indicators in time. The interactive controls in MSLT provide a virtual track-ball, pan and zoom, translucency adjustment, simulation playback, and simulation movie capture. In addition, geographical information on the fault segments and faults is displayed on text windows. Because of the extensive viewing controls, faults can be seen in relation to one another, and to the terrain. These relations can be realized in simulations. Correlated slips in parallel faults are visible in the playback of Virtual California simulations.

  9. A Quaternary fault database for central Asia

    NASA Astrophysics Data System (ADS)

    Mohadjer, Solmaz; Ehlers, Todd Alan; Bendick, Rebecca; Stübner, Konstanze; Strube, Timo

    2016-02-01

    Earthquakes represent the highest risk in terms of potential loss of lives and economic damage for central Asian countries. Knowledge of fault location and behavior is essential in calculating and mapping seismic hazard. Previous efforts in compiling fault information for central Asia have generated a large amount of data that are published in limited-access journals with no digital maps publicly available, or are limited in their description of important fault parameters such as slip rates. This study builds on previous work by improving access to fault information through a web-based interactive map and an online database with search capabilities that allow users to organize data by different fields. The data presented in this compilation include fault location, its geographic, seismic, and structural characteristics, short descriptions, narrative comments, and references to peer-reviewed publications. The interactive map displays 1196 fault traces and 34 000 earthquake locations on a shaded-relief map. The online database contains attributes for 123 faults mentioned in the literature, with Quaternary and geodetic slip rates reported for 38 and 26 faults respectively, and earthquake history reported for 39 faults. All data are accessible for viewing and download via http://www.geo.uni-tuebingen.de/faults/. This work has implications for seismic hazard studies in central Asia as it summarizes important fault parameters, and can reduce earthquake risk by enhancing public access to information. It also allows scientists and hazard assessment teams to identify structures and regions where data gaps exist and future investigations are needed.

  10. Experiments in fault tolerant software reliability

    NASA Technical Reports Server (NTRS)

    Mcallister, David F.; Vouk, Mladen A.

    1989-01-01

    Twenty functionally equivalent programs were built and tested in a multiversion software experiment. Following unit testing, all programs were subjected to an extensive system test. In the process sixty-one distinct faults were identified among the versions. Less than 12 percent of the faults exhibited varying degrees of positive correlation. The common-cause (or similar) faults spanned as many as 14 components. However, a majority of these faults were trivial, and easily detected by proper unit and/or system testing. Only two of the seven similar faults were difficult faults, and both were caused by specification ambiguities. One of these faults exhibited variable identical-and-wrong response span, i.e. response span which varied with the testing conditions and input data. Techniques that could have been used to avoid the faults are discussed. For example, it was determined that back-to-back testing of 2-tuples could have been used to eliminate about 90 percent of the faults. In addition, four of the seven similar faults could have been detected by using back-to-back testing of 5-tuples. It is believed that most, if not all, similar faults could have been avoided had the specifications been written using more formal notation, the unit testing phase was subject to more stringent standards and controls, and better tools for measuring the quality and adequacy of the test data (e.g. coverage) were used.

  11. [Early warning for various internal faults of GIS based on ultraviolet spectroscopy].

    PubMed

    Zhao, Yu; Wang, Xian-pei; Hu, Hong-hong; Dai, Dang-dang; Long, Jia-chuan; Tian, Meng; Zhu, Guo-wei; Huang, Yun-guang

    2015-02-01

    As the basis of accurate diagnosis, fault early-warning of gas insulation switchgear (GIS) focuses on the time-effectiveness and the applicability. It would be significant to research the method of unified early-warning for partial discharge (PD) and overheated faults in GIS. In the present paper, SO2 is proposed as the common and typical by-product. The unified monitoring could be achieved through ultraviolet spectroscopy (UV) detection of SO2. The derivative method and Savitzky-Golay filtering are employed for baseline correction and smoothing. The wavelength range of 290-310 nm is selected for quantitative detection of SO2. Through UV method, the spectral interference of SF6 and other complex by-products, e.g., SOF2 and SOF2, can be avoided and the features of trace SO2 in GIS can be extracted. The detection system is featured by compacted structure, low maintenance and satisfactory suitability in filed surveillance. By conducting SF6 decomposition experiments, including two types of PD faults and the overheated faults between 200-400 degrees C, the feasibility of proposed UV method has been verified. Fourier transform infrared spectroscopy and gas chromatography methods can be used for subsequent fault diagnosis. The different decomposition features in two kinds of faults are confirmed and the diagnosis strategy has been briefly analyzed. The main by-products under PD are SOF2 and SO2F2. The generated SO2 is significantly less than SOF2. More carbonous by-products will be generated when PD involves epoxy. By contrast, when the material of heater is stainless steel, SF6 decomposes at about 300 "C and the main by-products in overheated faults are SO2 and SO2F2. When heated over 350 degrees C, SO2 is generated much faster. SOz content stably increases when the GIS fault lasts. The faults types could be preliminarily identified based on the generation features of SO2.

  12. Arc burst pattern analysis fault detection system

    NASA Technical Reports Server (NTRS)

    Russell, B. Don (Inventor); Aucoin, B. Michael (Inventor); Benner, Carl L. (Inventor)

    1997-01-01

    A method and apparatus are provided for detecting an arcing fault on a power line carrying a load current. Parameters indicative of power flow and possible fault events on the line, such as voltage and load current, are monitored and analyzed for an arc burst pattern exhibited by arcing faults in a power system. These arcing faults are detected by identifying bursts of each half-cycle of the fundamental current. Bursts occurring at or near a voltage peak indicate arcing on that phase. Once a faulted phase line is identified, a comparison of the current and voltage reveals whether the fault is located in a downstream direction of power flow toward customers, or upstream toward a generation station. If the fault is located downstream, the line is de-energized, and if located upstream, the line may remain energized to prevent unnecessary power outages.

  13. Multiple sensor fault diagnosis for dynamic processes.

    PubMed

    Li, Cheng-Chih; Jeng, Jyh-Cheng

    2010-10-01

    Modern industrial plants are usually large scaled and contain a great amount of sensors. Sensor fault diagnosis is crucial and necessary to process safety and optimal operation. This paper proposes a systematic approach to detect, isolate and identify multiple sensor faults for multivariate dynamic systems. The current work first defines deviation vectors for sensor observations, and further defines and derives the basic sensor fault matrix (BSFM), consisting of the normalized basic fault vectors, by several different methods. By projecting a process deviation vector to the space spanned by BSFM, this research uses a vector with the resulted weights on each direction for multiple sensor fault diagnosis. This study also proposes a novel monitoring index and derives corresponding sensor fault detectability. The study also utilizes that vector to isolate and identify multiple sensor faults, and discusses the isolatability and identifiability. Simulation examples and comparison with two conventional PCA-based contribution plots are presented to demonstrate the effectiveness of the proposed methodology.

  14. A “mesh” of crossing faults: Fault networks of southern California

    NASA Astrophysics Data System (ADS)

    Janecke, S. U.

    2009-12-01

    Detailed geologic mapping of active fault systems in the western Salton Trough and northern Peninsular Ranges of southern California make it possible to expand the inventory of mapped and known faults by compiling and updating existing geologic maps, and analyzing high resolution imagery, LIDAR, InSAR, relocated hypocenters and other geophysical datasets. A fault map is being compiled on Google Earth and will ultimately discriminate between a range of different fault expressions: from well-mapped faults to subtle lineaments and geomorphic anomalies. The fault map shows deformation patterns in both crystalline and basinal deposits and reveals a complex fault mesh with many curious and unexpected relationships. Key findings are: 1) Many fault systems have mutually interpenetrating geometries, are grossly coeval, and allow faults to cross one another. A typical relationship reveals a dextral fault zone that appears to be continuous at the regional scale. In detail, however, there are no continuous NW-striking dextral fault traces and instead the master dextral fault is offset in a left-lateral sense by numerous crossing faults. Left-lateral faults also show small offsets where they interact with right lateral faults. Both fault sets show evidence of Quaternary activity. Examples occur along the Clark, Coyote Creek, Earthquake Valley and Torres Martinez fault zones. 2) Fault zones cross in other ways. There are locations where active faults continue across or beneath significant structural barriers. Major fault zones like the Clark fault of the San Jacinto fault system appears to end at NE-striking sinistral fault zones (like the Extra and Pumpkin faults) that clearly cross from the SW to the NE side of the projection of the dextral traces. Despite these blocking structures, there is good evidence for continuation of the dextral faults on the opposite sides of the crossing fault array. In some instances there is clear evidence (in deep microseismic alignments of

  15. Tracing the Geomorphic Signature of Lateral Faulting

    NASA Astrophysics Data System (ADS)

    Duvall, A. R.; Tucker, G. E.

    2012-12-01

    Active strike-slip faults are among the most dangerous geologic features on Earth. Unfortunately, it is challenging to estimate their slip rates, seismic hazard, and evolution over a range of timescales. An under-exploited tool in strike-slip fault characterization is quantitative analysis of the geomorphic response to lateral fault motion to extract tectonic information directly from the landscape. Past geomorphic work of this kind has focused almost exclusively on vertical motion, despite the ubiquity of horizontal motion in crustal deformation and mountain building. We seek to address this problem by investigating the landscape response to strike-slip faulting in two ways: 1) examining the geomorphology of the Marlborough Fault System (MFS), a suite of parallel strike-slip faults within the actively deforming South Island of New Zealand, and 2) conducting controlled experiments in strike-slip landscape evolution using the CHILD landscape evolution model. The MFS offers an excellent natural experiment site because fault initiation ages and cumulative displacements decrease from north to south, whereas slip rates increase over four fold across a region underlain by a single bedrock unit (Torlesse Greywacke). Comparison of planform and longitudinal profiles of rivers draining the MFS reveals strong disequilibrium within tributaries that drain to active fault strands, and suggests that river capture related to fault activity may be a regular process in strike-slip fault zones. Simple model experiments support this view. Model calculations that include horizontal motion as well as vertical uplift demonstrate river lengthening and shortening due to stream capture in response to shutter ridges sliding in front of stream outlets. These results suggest that systematic variability in fluvial knickpoint location, drainage area, and incision rates along different faults or fault segments may be expected in catchments upstream of strike-slip faults and could act as useful

  16. Perspective View, San Andreas Fault

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The prominent linear feature straight down the center of this perspective view is California's famous San Andreas Fault. The image, created with data from NASA's Shuttle Radar Topography Mission (SRTM), will be used by geologists studying fault dynamics and landforms resulting from active tectonics. This segment of the fault lies west of the city of Palmdale, Calif., about 100 kilometers (about 60 miles) northwest of Los Angeles. The fault is the active tectonic boundary between the North American plate on the right, and the Pacific plate on the left. Relative to each other, the Pacific plate is moving away from the viewer and the North American plate is moving toward the viewer along what geologists call a right lateral strike-slip fault. Two large mountain ranges are visible, the San Gabriel Mountains on the left and the Tehachapi Mountains in the upper right. Another fault, the Garlock Fault lies at the base of the Tehachapis; the San Andreas and the Garlock Faults meet in the center distance near the town of Gorman. In the distance, over the Tehachapi Mountains is California's Central Valley. Along the foothills in the right hand part of the image is the Antelope Valley, including the Antelope Valley California Poppy Reserve. The data used to create this image were acquired by SRTM aboard the Space Shuttle Endeavour, launched on February 11, 2000.

    This type of display adds the important dimension of elevation to the study of land use and environmental processes as observed in satellite images. The perspective view was created by draping a Landsat satellite image over an SRTM elevation model. Topography is exaggerated 1.5 times vertically. The Landsat image was provided by the United States Geological Survey's Earth Resources Observations Systems (EROS) Data Center, Sioux Falls, South Dakota.

    SRTM uses the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space

  17. Fuzzy logic for fault diagnosis

    NASA Astrophysics Data System (ADS)

    Comly, James B.; Bonissone, Piero P.; Dausch, Mark E.

    1991-02-01

    Advanced real-time digital controls for complex plants or processes will use a model (an " Observer" ) which predicts the values for sensor readings expected from the actual plant these vote as alternate " sensors" if the real ones fail. We are exploring further use of the Observer for real-time embedded diagnostics based on high speed fuzzy logic chips just becoming available. We have established a Fuzzy Inferencing Test Bed for fuzzy logic applications. It uses a set of development tools which allow applications to be built and tested against simulated systems and then ported directly to a high speed fuzzy logic chip. With the Fuzzy Inferencing Test we investigate very high speed fuzzy logic to: isolate faults using static information and early fault information that evolves rapidly in time validate and smooth readings from redundant sensors and smoothly select alternate control modes in intelligent controllers. This paper reports our experience with fuzzy logic in these kinds of applications.

  18. Fault trees and imperfect coverage

    NASA Technical Reports Server (NTRS)

    Dugan, Joanne B.

    1989-01-01

    A new algorithm is presented for solving the fault tree. The algorithm includes the dynamic behavior of the fault/error handling model but obviates the need for the Markov chain solution. As the state space is expanded in a breadth-first search (the same is done in the conversion to a Markov chain), the state's contribution to each future state is calculated exactly. A dynamic state truncation technique is also presented; it produces bounds on the unreliability of the system by considering only part of the state space. Since the model is solved as the state space is generated, the process can be stopped as soon as the desired accuracy is reached.

  19. Fault Injection Techniques and Tools

    NASA Technical Reports Server (NTRS)

    Hsueh, Mei-Chen; Tsai, Timothy K.; Iyer, Ravishankar K.

    1997-01-01

    Dependability evaluation involves the study of failures and errors. The destructive nature of a crash and long error latency make it difficult to identify the causes of failures in the operational environment. It is particularly hard to recreate a failure scenario for a large, complex system. To identify and understand potential failures, we use an experiment-based approach for studying the dependability of a system. Such an approach is applied not only during the conception and design phases, but also during the prototype and operational phases. To take an experiment-based approach, we must first understand a system's architecture, structure, and behavior. Specifically, we need to know its tolerance for faults and failures, including its built-in detection and recovery mechanisms, and we need specific instruments and tools to inject faults, create failures or errors, and monitor their effects.

  20. Heat flow, strong near-fault seismic waves, and near-fault tectonics on the central San Andreas Fault

    NASA Astrophysics Data System (ADS)

    Sleep, Norman H.

    2016-05-01

    The main San Andreas Fault strikes subparallel to compressional folds and thrust faults. Its fault-normal traction is on average a factor of γ=1+2μthr>(√(1+μthr2)+μthr>), where μthr is the coefficient of friction for thrust faults, times the effective lithostatic pressure. A useful upper limit for μthr of 0.6 (where γ is 3.12) is obtained from the lack of heat flow anomalies by considering off-fault convergence at a rate of 1 mm/yr for 10 km across strike. If the fault-normal traction is in fact this high, the well-known heat flow constraint of average stresses of 10-20 MPa during strike slip on the main fault becomes more severe. Only a few percent of the total slip during earthquakes can occur at the peak stress before dynamic mechanisms weaken the fault. The spatial dimension of the high-stress rupture-tip zone is ˜10 m for γ = 3.12 and, for comparison, ˜100 m for γ = 1. High dynamic stresses during shaking occur within these distances of the fault plane. In terms of scalars, fine-scale tectonic stresses cannot exceed the difference between failure stress and dynamic stress. Plate-scale slip causes stresses to build up near geometrical irregularities of the fault plane. Strong dynamic stresses near the rupture tip facilitate anelastic deformation with the net effects of relaxing the local deviatoric tectonic stress and accommodating deformation around the irregularities. There also is a mild tendency for near-fault material to extrude upward. Slip on minor thrust faults causes the normal traction on the main fault to be spatially variable.

  1. The susitna glacier thrust fault: Characteristics of surface ruptures on the fault that initiated the 2002 denali fault earthquake

    USGS Publications Warehouse

    Crone, A.J.; Personius, S.F.; Craw, P.A.; Haeussler, P.J.; Staft, L.A.

    2004-01-01

    The 3 November 2002 Mw 7.9 Denali fault earthquake sequence initiated on the newly discovered Susitna Glacier thrust fault and caused 48 km of surface rupture. Rupture of the Susitna Glacier fault generated scarps on ice of the Susitna and West Fork glaciers and on tundra and surficial deposits along the southern front of the central Alaska Range. Based on detailed mapping, 27 topographic profiles, and field observations, we document the characteristics and slip distribution of the 2002 ruptures and describe evidence of pre-2002 ruptures on the fault. The 2002 surface faulting produced structures that range from simple folds on a single trace to complex thrust-fault ruptures and pressure ridges on multiple, sinuous strands. The deformation zone is locally more than 1 km wide. We measured a maximum vertical displacement of 5.4 m on the south-directed main thrust. North-directed backthrusts have more than 4 m of surface offset. We measured a well-constrained near-surface fault dip of about 19?? at one site, which is considerably less than seismologically determined values of 35??-48??. Surface-rupture data yield an estimated magnitude of Mw 7.3 for the fault, which is similar to the seismological value of Mw 7.2. Comparison of field and seismological data suggest that the Susitna Glacier fault is part of a large positive flower structure associated with northwest-directed transpressive deformation on the Denali fault. Prehistoric scarps are evidence of previous rupture of the Sustina Glacier fault, but additional work is needed to determine if past failures of the Susitna Glacier fault have consistently induced rupture of the Denali fault.

  2. New insights on Southern Coyote Creek Fault and Superstition Hills Fault

    NASA Astrophysics Data System (ADS)

    van Zandt, A. J.; Mellors, R. J.; Rockwell, T. K.; Burgess, M. K.; O'Hare, M.

    2007-12-01

    Recent field work has confirmed an extension of the southern Coyote Creek (CCF) branch of the San Jacinto fault in the western Salton trough. The fault marks the western edge of an area of subsidence caused by groundwater extraction, and field measurements suggest that recent strike-slip motion has occurred on this fault as well. We attempt to determine whether this fault connects at depth with the Superstition Hills fault (SHF) to the southeast by modeling observed surface deformation between the two faults measured by InSAR. Stacked ERS (descending) InSAR data from 1992 to 2000 is initially modeled using a finite fault in an elastic half-space. Observed deformation along the SHF and Elmore Ranch fault is modeled assuming shallow (< 5 km) creep. We test various models to explain surface deformation between the two faults.

  3. Inverter Ground Fault Overvoltage Testing

    SciTech Connect

    Hoke, Andy; Nelson, Austin; Chakraborty, Sudipta; Chebahtah, Justin; Wang, Trudie; McCarty, Michael

    2015-08-12

    This report describes testing conducted at NREL to determine the duration and magnitude of transient overvoltages created by several commercial PV inverters during ground fault conditions. For this work, a test plan developed by the Forum on Inverter Grid Integration Issues (FIGII) has been implemented in a custom test setup at NREL. Load rejection overvoltage test results were reported previously in a separate technical report.

  4. New mapping and structural constraints on the Queen Charlotte-Fairweather Fault system, southeast Alaska

    NASA Astrophysics Data System (ADS)

    Levoir, M. A.; Roland, E. C.; Gulick, S. P.; Haeussler, P. J.; Christeson, G. L.; Van Avendonk, H. J.

    2013-12-01

    The dextral Queen Charlotte-Fairweather Fault lies along the western margin of Canada and southeastern Alaska, a transform plate boundary accommodating motion between the North American and Pacific Plates. The Fairweather Fault is the northern extension of the Queen Charlotte Fault and has numerous and complex splays, including the Chichagof-Baranof Fault, the Peril Strait Fault, the Chatham Strait Fault, and the Icy Point-Lituya Bay Fault. Except for a few small areas, these fault systems have not been mapped in detail. We present updated geometries and fault maps of the entirety of the strike-slip system using seismic reflection and bathymetric data, including a 2004 seismic reflection survey (EW0408), 2005 United Nations Commission on Law of the Sea multibeam bathymetry, and legacy data from the U.S. Geological Survey (USGS) and the National Geophysical Data Center. This work is highly relevant for earthquake hazard research and mitigation in southeast Alaska. Several large (> Mw 7.0) earthquakes have occurred along this margin in the last century, impacting communities of southeastern Alaska and western Canada. Two large, recent events include 1) a Mw 7.7 earthquake that took place on 28 October 2012 near the Haida Gwaii Islands offshore of western Canada, and 2) a Mw 7.5 event which occurred on 05 January 2013, 330 km to the northwest and offshore of Craig, Alaska. Interestingly, the Haida Gwaii earthquake ruptured as a thrust event and the Craig earthquake ruptured with a near-vertical dextral strike-slip mechanism. Since a change in Pacific Plate motion around 4 million years ago, the southern Queen Charlotte Fault system has been obliquely converging at a rate of 20 mm/year, with the boundary accommodating about 80 km of perpendicular motion over that time. This convergence explains the Haida Gwaii thrust earthquake, but leaves questions about the along-strike fault structure. Two opposing end-member theories suggest convergence is accommodated by either: 1

  5. DC superconducting fault current limiter

    NASA Astrophysics Data System (ADS)

    Tixador, P.; Villard, C.; Cointe, Y.

    2006-03-01

    There is a lack of satisfying solutions for fault currents using conventional technologies, especially in DC networks, where a superconducting fault current limiter could play a very important part. DC networks bring a lot of advantages when compared to traditional AC ones, in particular within the context of the liberalization of the electric market. Under normal operation in a DC network, the losses in the superconducting element are nearly zero and only a small, i.e. a low cost, refrigeration system is then required. The absence of zero crossing of a DC fault current favourably accelerates the normal zone propagation. The very high current slope at the time of the short circuit in a DC grid is another favourable parameter. The material used for the experiments is YBCO deposited on Al2O3 as well as YBCO coated conductors. The DC limitation experiments are compared to AC ones at different frequencies (50-2000 Hz). Careful attention is paid to the quench homogenization, which is one of the key issues for an SC FCL. The University of Geneva has proposed constrictions. We have investigated an operating temperature higher than 77 K. As for YBCO bulk, an operation closer to the critical temperature brings a highly improved homogeneity in the electric field development. The material can then absorb large energies without degradation. We present tests at various temperatures. These promising results are to be confirmed over long lengths.

  6. Watching Faults Grow in Sand

    NASA Astrophysics Data System (ADS)

    Cooke, M. L.

    2015-12-01

    Accretionary sandbox experiments provide a rich environment for investigating the processes of fault development. These experiments engage students because 1) they enable direct observation of fault growth, which is impossible in the crust (type 1 physical model), 2) they are not only representational but can also be manipulated (type 2 physical model), 3) they can be used to test hypotheses (type 3 physical model) and 4) they resemble experiments performed by structural geology researchers around the world. The structural geology courses at UMass Amherst utilize a series of accretionary sandboxes experiments where students first watch a video of an experiment and then perform a group experiment. The experiments motivate discussions of what conditions they would change and what outcomes they would expect from these changes; hypothesis development. These discussions inevitably lead to calculations of the scaling relationships between model and crustal fault growth and provide insight into the crustal processes represented within the dry sand. Sketching of the experiments has been shown to be a very effective assessment method as the students reveal which features they are analyzing. Another approach used at UMass is to set up a forensic experiment. The experiment is set up with spatially varying basal friction before the meeting and students must figure out what the basal conditions are through the experiment. This experiment leads to discussions of equilibrium and force balance within the accretionary wedge. Displacement fields can be captured throughout the experiment using inexpensive digital image correlation techniques to foster quantitative analysis of the experiments.

  7. CONTROL AND FAULT DETECTOR CIRCUIT

    DOEpatents

    Winningstad, C.N.

    1958-04-01

    A power control and fault detectcr circuit for a radiofrequency system is described. The operation of the circuit controls the power output of a radio- frequency power supply to automatically start the flow of energizing power to the radio-frequency power supply and to gradually increase the power to a predetermined level which is below the point where destruction occurs upon the happening of a fault. If the radio-frequency power supply output fails to increase during such period, the control does not further increase the power. On the other hand, if the output of the radio-frequency power supply properly increases, then the control continues to increase the power to a maximum value. After the maximumn value of radio-frequency output has been achieved. the control is responsive to a ''fault,'' such as a short circuit in the radio-frequency system being driven, so that the flow of power is interrupted for an interval before the cycle is repeated.

  8. Hamlet's Transformation.

    NASA Astrophysics Data System (ADS)

    Usher, P. D.

    1997-12-01

    William Shakespeare's Hamlet has much evidence to suggest that the Bard was aware of the cosmological models of his time, specifically the geocentric bounded Ptolemaic and Tychonic models, and the infinite Diggesian. Moreover, Shakespeare describes how the Ptolemaic model is to be transformed to the Diggesian. Hamlet's "transformation" is the reason that Claudius, who personifies the Ptolemaic model, summons Rosencrantz and Guildenstern, who personify the Tychonic. Pantometria, written by Leonard Digges and his son Thomas in 1571, contains the first technical use of the word "transformation." At age thirty, Thomas Digges went on to propose his Perfit Description, as alluded to in Act Five where Hamlet's age is given as thirty. In Act Five as well, the words "bore" and "arms" refer to Thomas' vocation as muster-master and his scientific interest in ballistics. England's leading astronomer was also the father of the poet whose encomium introduced the First Folio of 1623. His oldest child Dudley became a member of the Virginia Company and facilitated the writing of The Tempest. Taken as a whole, such manifold connections to Thomas Digges support Hotson's contention that Shakespeare knew the Digges family. Rosencrantz and Guildenstern in Hamlet bear Danish names because they personify the Danish model, while the king's name is latinized like that of Claudius Ptolemaeus. The reason Shakespeare anglicized "Amleth" to "Hamlet" was because he saw a parallel between Book Three of Saxo Grammaticus and the eventual triumph of the Diggesian model. But Shakespeare eschewed Book Four, creating this particular ending from an infinity of other possibilities because it "suited his purpose," viz. to celebrate the concept of a boundless universe of stars like the Sun.

  9. TRANSFORMER APPARATUS

    DOEpatents

    Wolfgang, F.; Nicol, J.

    1962-11-01

    Transformer apparatus is designed for measuring the amount of a paramagnetic substance dissolved or suspended in a diamagnetic liquid. The apparatus consists of a cluster of tubes, some of which are closed and have sealed within the diamagnetic substance without any of the paramagnetic material. The remaining tubes are open to flow of the mix- ture. Primary and secondary conductors are wrapped around the tubes in such a way as to cancel noise components and also to produce a differential signal on the secondaries based upon variations of the content of the paramagnetic material. (AEC)

  10. Influence of fault trend, fault bends, and fault convergence on shallow structure, geomorphology, and hazards, Hosgri strike-slip fault, offshore central California

    NASA Astrophysics Data System (ADS)

    Johnson, S. Y.; Watt, J. T.; Hartwell, S. R.

    2012-12-01

    We mapped a ~94-km-long portion of the right-lateral Hosgri Fault Zone from Point Sal to Piedras Blancas in offshore central California using high-resolution seismic reflection profiles, marine magnetic data, and multibeam bathymetry. The database includes 121 seismic profiles across the fault zone and is perhaps the most comprehensive reported survey of the shallow structure of an active strike-slip fault. These data document the location, length, and near-surface continuity of multiple fault strands, highlight fault-zone heterogeneity, and demonstrate the importance of fault trend, fault bends, and fault convergences in the development of shallow structure and tectonic geomorphology. The Hosgri Fault Zone is continuous through the study area passing through a broad arc in which fault trend changes from about 338° to 328° from south to north. The southern ~40 km of the fault zone in this area is more extensional, resulting in accommodation space that is filled by deltaic sediments of the Santa Maria River. The central ~24 km of the fault zone is characterized by oblique convergence of the Hosgri Fault Zone with the more northwest-trending Los Osos and Shoreline Faults. Convergence between these faults has resulted in the formation of local restraining and releasing fault bends, transpressive uplifts, and transtensional basins of varying size and morphology. We present a hypothesis that links development of a paired fault bend to indenting and bulging of the Hosgri Fault by a strong crustal block translated to the northwest along the Shoreline Fault. Two diverging Hosgri Fault strands bounding a central uplifted block characterize the northern ~30 km of the Hosgri Fault in this area. The eastern Hosgri strand passes through releasing and restraining bends; the releasing bend is the primary control on development of an elongate, asymmetric, "Lazy Z" sedimentary basin. The western strand of the Hosgri Fault Zone passes through a significant restraining bend and

  11. Fault tolerant operation of switched reluctance machine

    NASA Astrophysics Data System (ADS)

    Wang, Wei

    The energy crisis and environmental challenges have driven industry towards more energy efficient solutions. With nearly 60% of electricity consumed by various electric machines in industry sector, advancement in the efficiency of the electric drive system is of vital importance. Adjustable speed drive system (ASDS) provides excellent speed regulation and dynamic performance as well as dramatically improved system efficiency compared with conventional motors without electronics drives. Industry has witnessed tremendous grow in ASDS applications not only as a driving force but also as an electric auxiliary system for replacing bulky and low efficiency auxiliary hydraulic and mechanical systems. With the vast penetration of ASDS, its fault tolerant operation capability is more widely recognized as an important feature of drive performance especially for aerospace, automotive applications and other industrial drive applications demanding high reliability. The Switched Reluctance Machine (SRM), a low cost, highly reliable electric machine with fault tolerant operation capability, has drawn substantial attention in the past three decades. Nevertheless, SRM is not free of fault. Certain faults such as converter faults, sensor faults, winding shorts, eccentricity and position sensor faults are commonly shared among all ASDS. In this dissertation, a thorough understanding of various faults and their influence on transient and steady state performance of SRM is developed via simulation and experimental study, providing necessary knowledge for fault detection and post fault management. Lumped parameter models are established for fast real time simulation and drive control. Based on the behavior of the faults, a fault detection scheme is developed for the purpose of fast and reliable fault diagnosis. In order to improve the SRM power and torque capacity under faults, the maximum torque per ampere excitation are conceptualized and validated through theoretical analysis and

  12. Composite transform-convergent plate boundaries: description and discussion

    USGS Publications Warehouse

    Ryan, H.F.; Coleman, P.J.

    1992-01-01

    The leading edge of the overriding plate at an obliquely convergent boundary is commonly sliced by a system of strike-slip faults. This fault system is often structurally complex, and may show correspondingly uneven strain effects, with great vertical and translational shifts of the component blocks of the fault system. The stress pattern and strain effects vary along the length of the system and change through time. These margins are considered to be composite transform-convergent (CTC) plate boundaries. Examples are given of structures formed along three CTC boundaries: the Aleutian Ridge, the Solomon Islands, and the Philippines. The dynamism of the fault system along a CTC boundary can enhance vertical tectonism and basin formation. This concept provides a framework for the evaluation of petroleum resources related to basin formation, and mineral exploration related to igneous activity associated with transtensional processes. ?? 1992.

  13. Stacking faults in austempered ductile iron

    SciTech Connect

    Hermida, J.D.

    1996-06-01

    During last decade, Austempered Ductile Iron (ADI) has been successfully used as an acceptable replacement material for steel in many applications, due to the relatively high strength and reasonable ductility obtained. These properties are the result of the special microstructure exhibited by this material at the end of the upper bainite reaction: ferrite platelets surrounded by high carbon stabilized austenite. However, at the beginning of the austempering treatment, the existence of interdendritic low carbon austenite is revealed by its transformation to martensite when cooling the sample or during subsequent deformation. The completion of the upper bainite reaction is of decisive importance to mechanical properties because the remaining martensite reduces ductility. It was observed that the rate of the upper bainite reaction is governed by the carbon content difference between the low and high carbon austenites. The carbon content is obtained by the lattice parameter measurement, because there exists a known expression that relates both magnitudes. Several works have used X-ray diffraction to measure the lattice parameter and phase concentrations as a function of austempering time. In these works, the lattice parameters were obtained directly from the {l_brace}220{r_brace} and {l_brace}311{r_brace} peaks position. The purpose of this work is to show more precise lattice parameters measurement and, very closely related to this, the existence of stacking faults in austenite, even at times within the processing window.

  14. Multi-scale autocorrelation via morphological wavelet slices for rolling element bearing fault diagnosis

    NASA Astrophysics Data System (ADS)

    Li, Chuan; Liang, Ming; Zhang, Yi; Hou, Shumin

    2012-08-01

    Fault features of rolling element bearings can be reflected by geometrical structures of the bearing vibration signals. These symptoms, however, often spread over various morphological scales without a known pattern. For this reason, we propose a multi-scale autocorrelation via morphological wavelet slices (MAMWS) approach to detect bearing fault signatures. The vibration measurement of a bearing is decomposed using morphological stationary wavelet with different resolutions of structuring elements. The extracted temporal components are then transformed to form a frequency-domain view of morphological slices by the Fourier transform. Although this three-dimensional representation is more intuitive in terms of fault diagnosis, the existence of the noise may reduce its readability. Hence the autocorrelation function is exploited to produce a multi-scale autocorrelation spectrogram from which the maximal autocorrelation values of all frequencies are aggregated into an ichnographical spectral representation. Accordingly the fault signature is highlighted for easy diagnosis of bearing faults. The effectiveness of the proposed approach has been demonstrated by both the simulation and experimental signal analyses.

  15. Novel Gauss-Hermite integration based Bayesian inference on optimal wavelet parameters for bearing fault diagnosis

    NASA Astrophysics Data System (ADS)

    Wang, Dong; Tsui, Kwok-Leung; Zhou, Qiang

    2016-05-01

    Rolling element bearings are commonly used in machines to provide support for rotating shafts. Bearing failures may cause unexpected machine breakdowns and increase economic cost. To prevent machine breakdowns and reduce unnecessary economic loss, bearing faults should be detected as early as possible. Because wavelet transform can be used to highlight impulses caused by localized bearing faults, wavelet transform has been widely investigated and proven to be one of the most effective and efficient methods for bearing fault diagnosis. In this paper, a new Gauss-Hermite integration based Bayesian inference method is proposed to estimate the posterior distribution of wavelet parameters. The innovations of this paper are illustrated as follows. Firstly, a non-linear state space model of wavelet parameters is constructed to describe the relationship between wavelet parameters and hypothetical measurements. Secondly, the joint posterior probability density function of wavelet parameters and hypothetical measurements is assumed to follow a joint Gaussian distribution so as to generate Gaussian perturbations for the state space model. Thirdly, Gauss-Hermite integration is introduced to analytically predict and update moments of the joint Gaussian distribution, from which optimal wavelet parameters are derived. At last, an optimal wavelet filtering is conducted to extract bearing fault features and thus identify localized bearing faults. Two instances are investigated to illustrate how the proposed method works. Two comparisons with the fast kurtogram are used to demonstrate that the proposed method can achieve better visual inspection performances than the fast kurtogram.

  16. A Log-Scaling Fault Tolerant Agreement Algorithm for a Fault Tolerant MPI

    SciTech Connect

    Hursey, Joshua J; Naughton, III, Thomas J; Vallee, Geoffroy R; Graham, Richard L

    2011-01-01

    The lack of fault tolerance is becoming a limiting factor for application scalability in HPC systems. The MPI does not provide standardized fault tolerance interfaces and semantics. The MPI Forum's Fault Tolerance Working Group is proposing a collective fault tolerant agreement algorithm for the next MPI standard. Such algorithms play a central role in many fault tolerant applications. This paper combines a log-scaling two-phase commit agreement algorithm with a reduction operation to provide the necessary functionality for the new collective without any additional messages. Error handling mechanisms are described that preserve the fault tolerance properties while maintaining overall scalability.

  17. A Quaternary Fault Database for Central Asia

    NASA Astrophysics Data System (ADS)

    Mohadjer, S.; Ehlers, T. A.; Bendick, R.; Stübner, K.; Strube, T.

    2015-09-01

    Earthquakes represent the highest risk in terms of potential loss of lives and economic damage for Central Asian countries. Knowledge of fault location and behavior is essential in calculating and mapping seismic hazard. Previous efforts in compiling fault information for Central Asia have generated a large amount of data that are published in limited-access journals with no digital maps publicly available, or are limited in their description of important fault parameters such as slip rates. This study builds on previous work by improving access to fault information through a web-based interactive map and an online database with search capabilities that allow users to organize data by different fields. The data presented in this compilation include fault location, its geographic, seismic and structural characteristics, short descriptions, narrative comments and references to peer-reviewed publications. The interactive map displays 1196 fault segments and 34 000 earthquake locations on a shaded-relief map. The online database contains attributes for 122 faults mentioned in the literature, with Quaternary and geodetic slip rates reported for 38 and 26 faults respectively, and earthquake history reported for 39 faults. This work has implications for seismic hazard studies in Central Asia as it summarizes important fault parameters, and can reduce earthquake risk by enhancing public access to information. It also allows scientists and hazard assessment teams to identify structures and regions where data gaps exist and future investigations are needed.

  18. Learning and diagnosing faults using neural networks

    NASA Technical Reports Server (NTRS)

    Whitehead, Bruce A.; Kiech, Earl L.; Ali, Moonis

    1990-01-01

    Neural networks have been employed for learning fault behavior from rocket engine simulator parameters and for diagnosing faults on the basis of the learned behavior. Two problems in applying neural networks to learning and diagnosing faults are (1) the complexity of the sensor data to fault mapping to be modeled by the neural network, which implies difficult and lengthy training procedures; and (2) the lack of sufficient training data to adequately represent the very large number of different types of faults which might occur. Methods are derived and tested in an architecture which addresses these two problems. First, the sensor data to fault mapping is decomposed into three simpler mappings which perform sensor data compression, hypothesis generation, and sensor fusion. Efficient training is performed for each mapping separately. Secondly, the neural network which performs sensor fusion is structured to detect new unknown faults for which training examples were not presented during training. These methods were tested on a task of fault diagnosis by employing rocket engine simulator data. Results indicate that the decomposed neural network architecture can be trained efficiently, can identify faults for which it has been trained, and can detect the occurrence of faults for which it has not been trained.

  19. A stochastic fault model. 2. Time-dependent case.

    USGS Publications Warehouse

    Andrews, D.J.

    1981-01-01

    A random model of fault motion in an earthquake is formulated by assuming that the slip velocity is a random function of position and time truncated at zero, so that it does not have negative values. This random function is chosen to be self-affine; that is, on change of length scale, the function is multiplied by a scale factor but is otherwise unchanged statistically. A snapshot of slip velocity at a given time resembles a cluster of islands with rough topography; the final slip function is a smoother island or cluster of islands. In the Fourier transform domain, shear traction on the fault equals the slip velocity times an impedance function. The fact that this impedance function has a pole at zero frequency implies that traction and slip velocity cannot have the same spectral dependence in space and time. To describe stress fluctuations of the order of 100 bars when smoothed over a length of kilometers and of the order of kilobars at the grain size, shear traction must have a one-dimensional power spectrum is space proportional to the reciprocal wave number. Then the one-dimensional power spectrum for the slip velocity is proportional to the reciprocal wave number squared and for slip to its cube. If slip velocity has the same power law spectrum in time as in space, then the spectrum of ground acceleration with be flat (white noise) both on the fault and in the far field.-Author

  20. DEM simulation of growth normal fault slip

    NASA Astrophysics Data System (ADS)

    Chu, Sheng-Shin; Lin, Ming-Lang; Nien, Wie-Tung; Chan, Pei-Chen

    2014-05-01

    Slip of the fault can cause deformation of shallower soil layers and lead to the destruction of infrastructures. Shanchiao fault on the west side of the Taipei basin is categorized. The activities of Shanchiao fault will cause the quaternary sediments underneath the Taipei basin to become deformed. This will cause damage to structures, traffic construction, and utility lines within the area. It is determined from data of geological drilling and dating, Shanchiao fault has growth fault. In experiment, a sand box model was built with non-cohesive sand soil to simulate the existence of growth fault in Shanchiao Fault and forecast the effect on scope of shear band development and ground differential deformation. The results of the experiment showed that when a normal fault containing growth fault, at the offset of base rock the shear band will develop upward along with the weak side of shear band of the original topped soil layer, and this shear band will develop to surface much faster than that of single top layer. The offset ratio (basement slip / lower top soil thickness) required is only about 1/3 of that of single cover soil layer. In this research, it is tried to conduct numerical simulation of sand box experiment with a Discrete Element Method program, PFC2D, to simulate the upper covering sand layer shear band development pace and scope of normal growth fault slip. Results of simulation indicated, it is very close to the outcome of sand box experiment. It can be extended to application in water pipeline project design around fault zone in the future. Keywords: Taipei Basin, Shanchiao fault, growth fault, PFC2D

  1. Perspective View, San Andreas Fault

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The prominent linear feature straight down the center of this perspective view is the San Andreas Fault in an image created with data from NASA's shuttle Radar Topography Mission (SRTM), which will be used by geologists studying fault dynamics and landforms resulting from active tectonics. This segment of the fault lies west of the city of Palmdale, California, about 100 kilometers (about 60 miles) northwest of Los Angeles. The fault is the active tectonic boundary between the North American plate on the right, and the Pacific plate on the left. Relative to each other, the Pacific plate is moving away from the viewer and the North American plate is moving toward the viewer along what geologists call a right lateral strike-slip fault. This area is at the junction of two large mountain ranges, the San Gabriel Mountains on the left and the Tehachapi Mountains on the right. Quail Lake Reservoir sits in the topographic depression created by past movement along the fault. Interstate 5 is the prominent linear feature starting at the left edge of the image and continuing into the fault zone, passing eventually over Tejon Pass into the Central Valley, visible at the upper left.

    This type of display adds the important dimension of elevation to the study of land use and environmental processes as observed in satellite images. The perspective view was created by draping a Landsat satellite image over an SRTM elevation model. Topography is exaggerated 1.5 times vertically. The Landsat image was provided by the United States Geological Survey's Earth Resources Observations Systems (EROS) Data Center, Sioux Falls, South Dakota.

    Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11,2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994

  2. Kinematics of the oblique faults in the east central Gulf of Suez Rift, Wadi Araba, Sinai Peninsula, Egypt

    NASA Astrophysics Data System (ADS)

    Abdeen, Mamdouh; Abdelmaksoud, Ashraf

    2014-05-01

    The Oligo-Miocene Gulf of Suez rift is characterized by four fault trends; a rift-parallel trend, two trends oblique to the rift trend and a cross trend. The rift-parallel trend strikes 310o to 340o and is referred to as the Clysmic trend. The two trends, which are oblique to the Clysmic trend, strike 350o to 030o and 280o to 310o; the first has been referred to as the north-oblique (N-oblique), and the second as the northwest-oblique (NW-oblique). The cross trend includes faults nearly orthogonal to the Clysmic trend i.e. they strike between 050o and 075o. Image interpretation and detailed field mapping and structural studies at a scale of 1: 20,000 of the Wadi Araba area in southwest Sinai Peninsula indicate e Clysmic faults are mostly normal showing major dip-slip movements. The oblique faults were found to be younger than the Clysmic faults and that the N-oblique faults are characterized by major sinistral strike-slip movement, while the NW-oblique faults are characterized by major dextral strike-slip movement. Cross cutting relationship, geometry and palaeostress analysis indicate that the oblique faults are conjugate Riedel shears originated due to NE to NNE extension related to the Aqaba-Levant transform that has been active since the Middle Miocene.

  3. A Compound fault diagnosis for rolling bearings method based on blind source separation and ensemble empirical mode decomposition.

    PubMed

    Wang, Huaqing; Li, Ruitong; Tang, Gang; Yuan, Hongfang; Zhao, Qingliang; Cao, Xi

    2014-01-01

    A Compound fault signal usually contains multiple characteristic signals and strong confusion noise, which makes it difficult to separate week fault si