Sample records for andreas fault system

  1. Mantle strength of the San Andreas fault system and the role of mantle-crust feedbacks

    NARCIS (Netherlands)

    Chatzaras, V.; Tikoff, B.; Newman, J.; Withers, A.C.; Drury, M.R.


    In lithospheric-scale strike-slip fault zones, upper crustal strength is well constrained from borehole observations and fault rock deformation experiments, but mantle strength is less well known. Using peridotite xenoliths, we show that the upper mantle below the San Andreas fault system (Californi

  2. Predictive Upper Cretaceous to Early Miocene Paleogeography of the San Andreas Fault System (United States)

    Burnham, K.


    Paleogeographic reconstruction of the region of the San Andreas fault was hampered for more than twenty years by the apparent incompatibility of authoritative lithologic correlations. These led to disparate estimates of dextral strike-slip offsets, notably 315 km between Pinnacles and Neenach Volcanics (Matthews, 1976), versus 563 km between Anchor Bay and Eagle Rest Peak (Ross et al., 1973). In addition, estimates of total dextral slip on the San Gregorio fault have ranged from 5 km to 185 km. Sixteen upper Cretaceous and Paleogene conglomerates of the California Coast Ranges, from Anchor Bay to Simi Valley, have been included in a multidisciplinary study. Detailed analysis, including microscopic petrography and microprobe geochemistry, verified Seiders and Cox's (1992) and Wentworth's (1996) correlation of the upper Cretaceous Strata of Anchor Bay with an unnamed conglomerate east of Half Moon Bay. Similar detailed study, with the addition of SHRIMP U/Pb zircon dating, verified that the Paleocene or Eocene Point Reyes Conglomerate at Point Reyes is a tectonically displaced segment of the Carmelo Formation of Point Lobos. These studies centered on identification of matching unique clast varieties, rather than on simply counting general clast types, and included analyses of matrices, fossils, paleocurrents, diagenesis, adjacent rocks, and stratigraphy. The work also led to three new correlations: the Point Reyes Conglomerate with granitic source rock at Point Lobos; a magnetic anomaly at Black Point with a magnetic anomaly near San Gregorio; and the Strata of Anchor Bay with previously established source rock, the potassium-poor Logan Gabbro (Ross et al., 1973) at a more recently recognized location (Brabb and Hanna, 1981; McLaughlin et al., 1996) just east of the San Gregorio fault, south of San Gregorio. From these correlations, an upper Cretaceous early Oligocene paleogeography of the San Andreas fault system was constructed that honors both the Anchor Bay

  3. Distributed Plate Boundary Deformation Across the San Andreas Fault System, Central California (United States)

    Dyson, M.; Titus, S. J.; Demets, C.; Tikoff, B.


    Plate boundaries are now recognized as broad zones of complex deformation as opposed to narrow zones with discrete offsets. When assessing how plate boundary deformation is accommodated, both spatially and temporally, it is therefore crucial to understand the relative contribution of the discrete and distributed components of deformation. The creeping segment of the San Andreas fault is an ideal location to study the distribution of plate boundary deformation for several reasons. First, the geometry of the fault system in central California is relatively simple. Plate motion is dominated by slip along the relatively linear strike-slip San Andreas fault, but also includes lesser slip along the adjacent and parallel Hosgri-San Gregorio and Rinconada faults, as well as within the borderlands between the three fault strands. Second, the aseismic character of the San Andreas fault in this region allows for the application of modern geodetic techniques to assess creep rates along the fault and across the region. Third, geologic structures within the borderlands are relatively well-preserved allowing comparison between modern and ancient rates and styles of deformation. Continuous GPS stations, alignment arrays surveys, and other geodetic methods demonstrate that approximately 5 mm/yr of distributed slip is accumulated (on top of the fault slip rate) across a 70-100 km wide region centered on the San Andreas fault. New campaign GPS data also suggest 2-5 mm/yr of deformation in the borderlands. These rates depend on the magnitude of the coseismic and postseismic corrections that must be made to our GPS time series to compensate for the 2003 San Simeon and 2004 Parkfield earthquakes, which rupture faults outside, but near the edges of our GPS network. The off-fault deformation pattern can be compared to the style of permanent deformation recorded in the geologic record. Fold and thrust belts in the borderlands are better developed in the Tertiary sedimentary rocks west of

  4. Mechanical insights into tectonic reorganization of the southern San Andreas fault system at ca. 1.1-1.5 Ma (United States)

    Fattaruso, L.; Cooke, M. L.; Dorsey, R. J.


    Reorganization of active fault systems may result from changes in relative plate motion and evolving fault geometries. Between ~1.5 and 1.1 Ma the southern San Andreas fault system underwent a major reorganization that included initiation of the San Jacinto fault zone, termination of slip on the extensional West Salton detachment fault, and reorganization of structures in the Mecca Hills northeast of the San Andreas fault during a local change from transtension to transpression conditions with no known change in Pacific-North America relative plate motion. The active trace of the southern San Andreas fault itself also evolved during this time, with shifts in activity from the Mission Creek to Mill Creek to the present-day active fault geometry of the San Bernardino, Garnet Hill, and Banning strands of the San Andreas fault. Although there is a rich geologic record of these changes, the mechanisms that controlled abandonment of active faults, initiation of new strands, and shifting loci of uplift are poorly understood. We use three-dimensional mechanical Boundary Element Method models to investigate this major tectonic reorganization at ~1.1-1.5 Ma. Previous mechanical modeling studies have examined the evolution of the southern San Andreas fault geometry in the San Gorgonio Pass using a series of snapshot models of the succession of active fault geometries. We use the same approach to explore the role of fault interaction and tectonic loading in abandonment of the West Salton detachment fault and initiation of the San Jacinto fault. The snapshots include: (1) regional transtension with an active West Salton detachment fault and active Mission Creek strand of the San Andreas fault; (2) cessation of local extension in combination with initiation of the San Jacinto fault in which we explore both north-to-south propagation and simultaneous growth; (3) shift of activity to the Mill Creek strand of the San Andreas fault; and (4) shift of activity to the present

  5. Deep crustal heterogeneity along and around the San Andreas fault system in central California and its relation to the segmentation (United States)

    Nishigami, Kin'ya


    The three-dimensional distribution of scatterers in the crust along and around the San Andreas fault system in central California is estimated using an inversion analysis of coda envelopes from local earthquakes. I analyzed 3801 wave traces from 157 events recorded at 140 stations of the Northern California Seismic Network. The resulting scatterer distribution shows a correlation with the San Gregorio, San Andreas, Hayward, and Calaveras faults. These faults seem to be almost vertical from the surface to ˜15 km depth. Some of the other scatterers are estimated to be at shallow depths, 0-5 km, below the Diablo Range, and these may be interpreted as being generated by topographic roughness. The depth distribution of scatterers shows relatively stronger scattering in the lower crust, at ˜15-25 km depth, especially between the San Andreas fault and the Hayward-Calaveras faults. This suggests a subhorizontal detachment structure connecting these two faults in the lower crust. Several clusters of scatterers are located along the San Andreas fault at intervals of ˜20-30 km from south of San Francisco to the intersection with the Calaveras fault. This part of the San Andreas fault appears to consist of partially locked segments, also ˜20-30 km long, which rupture during M6-7 events, and segment boundaries characterized by stronger scattering and stationary microseismicity. The segment boundaries delineated by the present analysis correspond with those estimated from the slip distribution of the great 1906 San Francisco earthquake, and from the fault geometry as reported by the Working Group on California Earthquake Probabilities [1990], although the segment boundaries along the San Andreas fault in and around the San Francisco Bay area are still uncertain.

  6. Recurrence of seismic migrations along the central California segment of the San Andreas fault system (United States)

    Wood, M.D.; Allen, S.S.


    VERIFICATIONS of tectonic concepts1 concerning seafloor spreading are emerging in a manner that has direct bearing on earthquake prediction. Although the gross pattern of worldwide seismicity contributed to the formulation of the plate tectonic hypothesis, it is the space-time characteristics of this seismicity that may contribute more toward understanding the kinematics and dynamics of the driving mechanism long speculated to originate in the mantle. If the lithosphere is composed of plates that move essentially as rigid bodies, then there should be seismic edge effects associated with this movement. It is these interplate effects, especially seismic migration patterns, that we discuss here. The unidirectional propagation at constant velocity (80 km yr-1 east to west) for earthquakes (M???7.2) on the Antblian fault for the period 1939 to 1956 (ref. 2) is one of the earliest observations of such a phenomenon. Similar studies3,4 of the Alaska Aleutian seismic zone and certain regions of the west coast of South America suggest unidirectional and recurring migrations of earthquakes (M???7.7) occur in these areas. Between these two regions along the great transform faults of the west coast of North America, there is some evidence 5 for unidirectional, constant velocity and recurrent migration of great earthquakes. The small population of earthquakes (M>7.2) in Savage's investigation5 indicates a large spatial gap along the San Andreas system in central California from 1830 to 1970. Previous work on the seismicity of this gap in central California indicates that the recurrence curves remain relatively constant, independent of large earthquakes, for periods up to a century6. Recurrence intervals for earthquakes along the San Andreas Fault have been calculated empirically by Wallace7 on the basis of geological evidence, surface measurements and assumptions restricted to the surficial seismic layer. Here we examine the evidence for recurrence of seismic migrations along

  7. Geophysical evidence for Quaternary deformation within the offshore San Andreas Fault System, Point Reyes Peninsula, California (United States)

    Stozek, B.


    Our previous work studying the rate and style of uplift of marine terraces on the Point Reyes Peninsula indicates the peninsula has been undergoing differential uplift due to interacting fault geometries in the offshore zone. To better understand offshore fault interactions, recently collected mini-sparker seismic reflection data acquired by the USGS and multi-beam bathymetric data acquired by California State University at Monterey Bay within the 3-mile (5 km) limit offshore of the Point Reyes Peninsula, are being used to reinterpret the tectono-stratigraphic framework of the San Andreas fault (SAF) system. Eight offshore Shell exploratory well logs that provide seismic velocity and paleontologic data are being used in conjunction with industry multichannel (deep-penetration) seismic reflection profiles to provide age control and extend the analyses beyond 3 mile limit of the high-resolution data. Isopach and structure maps of key stratigraphic intervals were generated to show how the stratigraphic units are influenced by fault interactions. These datasets allow for new interpretations of the offshore Neogene stratigraphy and the evolution of the Point Reyes fault, an offshore component of the SAF system. Observations of Quaternary sedimentary sequences in the high-resolution mini-sparker dataset provide evidence of localized areas of subsidence and uplift within the offshore SAF system. For example, the most recent angular unconformity above the Point Reyes fault deepens to the north where the fault bends from an east-west to a more northerly orientation. Stratigraphic horizons in the offshore zone are correlated with the same geologic units exposed on the Point Reyes Peninsula. Both unconformity-bounded sedimentary sequences mapped on reflection profiles in the offshore and marine terraces that have been uplifted on the peninsula are tied to sea-level fluctuations. Our new interpretation of the Point Reyes fault zone will be incorporated into a kinematic fault

  8. GPS Seismology and Earthquake Early Warning along the Southern San Andreas Fault System (United States)

    Bock, Y.; Jackson, M. E.


    We are in the process of upgrading CGPS stations in southern California to high-rate (1-10 Hz) real-time (latency Cerro Prieto faults, the region of highest strain rate in southern California and the narrowest part of the North America-Pacific plate boundary. South of the Big Bend, the zero velocity contour (the "boundary") between the North America and Pacific plates does not follow the SAF segment, but rather is located just east of the San Jacinto Fault (SJF) segment and then follows the Imperial and Cerro Prieto faults. The primary purpose of the real-time network is to serve as an early warning system for a large earthquake along the southern San Andreas Fault System by quickly measuring coseismic displacements, and also for GPS seismology to rapidly measure the associated dynamic displacements. The network, called the California Real Time Network (CRTN), also supplies data for real GPS surveys within the region and will provide rapid displacement waveforms to the SCEC data archive at Caltech in the event of a medium to large earthquake. Although the real-time data flow is currently at 1 Hz, the PBO stations have an internal buffer that records GPS data at a 10 Hz rate.

  9. Data-Derived Coulomb Stress Rate Uncertainties of the San Andreas Fault System (United States)

    Smith-Konter, B. R.; Solis, T.; Sandwell, D. T.


    Interseismic stress rates of the San Andreas Fault System (SAFS), derived from the present-day geodetic network spanning the North American-Pacific plate boundary, range from 0.5 - 7 MPa/100yrs and vary as a function of fault locking depth, slip rate, and fault geometry. Calculations of accumulated stress over several earthquake cycles, consistent with coseismic stress drops of ~3-7 MPa, also largely depend on the rupture history of a fault over the past few thousand years. However, uncertainties in paleoseismic slip history, combined with ongoing discrepancies in geologic/geodetic slip rates and variable locking depths throughout the earthquake cycle, can introduce uncertainties in stress rate and in present-day stress accumulation calculations. For example, a number of recent geodetic studies have challenged geologic slip rates along the SAFS, varying by as much as 25% of the total slip budget; geodetically determined locking depths, while within the bounds of seismicity, typically have uncertainties that range from 0.5 - 5 km; uncertainties in paleoseismic chronologies can span several decades, with slip uncertainties on the order of a few meters. Here we assess the importance of paleoseismic accuracy, variations in slip rates, and basic stress model components using a 3-D semi-analytic time-dependent deformation model of the SAFS. We perform a sensitivity analysis of Coulomb stress rate and present-day accumulated stress with respect to the six primary parameters of our model: slip rate, locking depth, mantle viscosity, elastic plate thickness, coefficient of friction, and slip history. In each case, we calculate a stress derivative with respect to a parameter over the estimated range of uncertainty, as well as any tradeoffs in parameters. Our results suggest that a 25% variation, or exchange, of slip rates between the primary SAFS and faults of the Eastern California Shear Zone (ECSZ) yields a respective decrease (SAFS) and increase (ECSZ) of stress rate by

  10. The stress shadow effect: a mechanical analysis of the evenly-spaced parallel strike-slip faults in the San Andreas fault system (United States)

    Zuza, A. V.; Yin, A.; Lin, J. C.


    Parallel evenly-spaced strike-slip faults are prominent in the southern San Andreas fault system, as well as other settings along plate boundaries (e.g., the Alpine fault) and within continental interiors (e.g., the North Anatolian, central Asian, and northern Tibetan faults). In southern California, the parallel San Jacinto, Elsinore, Rose Canyon, and San Clemente faults to the west of the San Andreas are regularly spaced at ~40 km. In the Eastern California Shear Zone, east of the San Andreas, faults are spaced at ~15 km. These characteristic spacings provide unique mechanical constraints on how the faults interact. Despite the common occurrence of parallel strike-slip faults, the fundamental questions of how and why these fault systems form remain unanswered. We address this issue by using the stress shadow concept of Lachenbruch (1961)—developed to explain extensional joints by using the stress-free condition on the crack surface—to present a mechanical analysis of the formation of parallel strike-slip faults that relates fault spacing and brittle-crust thickness to fault strength, crustal strength, and the crustal stress state. We discuss three independent models: (1) a fracture mechanics model, (2) an empirical stress-rise function model embedded in a plastic medium, and (3) an elastic-plate model. The assumptions and predictions of these models are quantitatively tested using scaled analogue sandbox experiments that show that strike-slip fault spacing is linearly related to the brittle-crust thickness. We derive constraints on the mechanical properties of the southern San Andreas strike-slip faults and fault-bounded crust (e.g., local fault strength and crustal/regional stress) given the observed fault spacing and brittle-crust thickness, which is obtained by defining the base of the seismogenic zone with high-resolution earthquake data. Our models allow direct comparison of the parallel faults in the southern San Andreas system with other similar strike

  11. A deep crustal fluid channel into the San Andreas Fault system near Parkfield, California (United States)

    Becken, M.; Ritter, O.; Park, S.K.; Bedrosian, P.A.; Weckmann, U.; Weber, M.


    Magnetotelluric (MT) data from 66 sites along a 45-km-long profile across the San Andreas Fault (SAF) were inverted to obtain the 2-D electrical resistivity structure of the crust near the San Andreas Fault Observatory at Depth (SAFOD). The most intriguing feature of the resistivity model is a steeply dipping upper crustal high-conductivity zone flanking the seismically defined SAF to the NE, that widens into the lower crust and appears to be connected to a broad conductivity anomaly in the upper mantle. Hypothesis tests of the inversion model suggest that upper and lower crustal and upper-mantle anomalies may be interconnected. We speculate that the high conductivities are caused by fluids and may represent a deep-rooted channel for crustal and/or mantle fluid ascent. Based on the chemical analysis of well waters, it was previously suggested that fluids can enter the brittle regime of the SAF system from the lower crust and mantle. At high pressures, these fluids can contribute to fault-weakening at seismogenic depths. These geochemical studies predicted the existence of a deep fluid source and a permeable pathway through the crust. Our resistivity model images a conductive pathway, which penetrates the entire crust, in agreement with the geochemical interpretation. However, the resistivity model also shows that the upper crustal branch of the high-conductivity zone is located NE of the seismically defined SAF, suggesting that the SAF does not itself act as a major fluid pathway. This interpretation is supported by both, the location of the upper crustal high-conductivity zone and recent studies within the SAFOD main hole, which indicate that pore pressures within the core of the SAF zone are not anomalously high, that mantle-derived fluids are minor constituents to the fault-zone fluid composition and that both the volume of mantle fluids and the fluid pressure increase to the NE of the SAF. We further infer from the MT model that the resistive Salinian block

  12. Predictive model of San Andreas fault system paleogeography, Late Cretaceous to early Miocene, derived from detailed multidisciplinary conglomerate correlations (United States)

    Burnham, Kathleen


    Paleogeographic reconstruction of the region of the San Andreas fault system in western California, USA, was hampered for more than two decades by the apparent incompatibility of authoritative lithologic correlations. These led to disparate estimates of dextral strike-slip offsets across the San Andreas fault, notably 315 km between Pinnacles and Neenach Volcanics, versus 563 km offset between Anchor Bay and Eagle Rest peak. Furthermore, one section of the San Andreas fault between Pinnacles and Point Reyes had been reported to have six pairs of features showing only ~ 30 km offset, while several younger features in that same area were reported consistent with ~ 315 km offset. Estimates of total dextral slip on the adjoining San Gregorio fault have ranged from 5 km to 185 km. Sixteen Upper Cretaceous and Paleogene conglomerates of the California Coast Ranges, from Anchor Bay to Simi Valley, were included in a multidisciplinary study centered on identification of matching unique clast varieties, rather than on simply counting general clast types. Detailed analysis verified the prior correlation of the Upper Cretaceous strata of Anchor Bay at Anchor Bay with a then-unnamed conglomerate at Highway 92 and Skyline Road (south of San Francisco); and verified that the Paleocene or Eocene Point Reyes Conglomerate at Point Reyes is a tectonically displaced segment of the Carmelo Formation of Point Lobos (near Monterey). The work also led to three new correlations: Point Reyes Conglomerate with granitic source rock at Point Lobos; a magnetic anomaly at Black Point (near Sea Ranch) with a magnetic anomaly near San Gregorio; and strata of Anchor Bay with previously established source rock, the potassium-poor Logan Gabbro of Eagle Rest peak, at a more recently recognized subsurface location just east of the San Gregorio fault, south of San Gregorio. From these correlations, a Late Cretaceous to early Oligocene paleogeography was constructed which was unique in utilizing modern

  13. Retardations in fault creep rates before local moderate earthquakes along the San Andreas fault system, central California (United States)

    Burford, R.O.


    Records of shallow aseismic slip (fault creep) obtained along parts of the San Andreas and Calaveras faults in central California demonstrate that significant changes in creep rates often have been associated with local moderate earthquakes. An immediate postearthquake increase followed by gradual, long-term decay back to a previous background rate is generally the most obvious earthquake effect on fault creep. This phenomenon, identified as aseismic afterslip, usually is characterized by above-average creep rates for several months to a few years. In several cases, minor step-like movements, called coseismic slip events, have occurred at or near the times of mainshocks. One extreme case of coseismic slip, recorded at Cienega Winery on the San Andreas fault 17.5 km southeast of San Juan Bautista, consisted of 11 mm of sudden displacement coincident with earthquakes of ML=5.3 and ML=5.2 that occurred 2.5 minutes apart on 9 April 1961. At least one of these shocks originated on the main fault beneath the winery. Creep activity subsequently stopped at the winery for 19 months, then gradually returned to a nearly steady rate slightly below the previous long-term average. The phenomena mentioned above can be explained in terms of simple models consisting of relatively weak material along shallow reaches of the fault responding to changes in load imposed by sudden slip within the underlying seismogenic zone. In addition to coseismic slip and afterslip phenomena, however, pre-earthquake retardations in creep rates also have been observed. Onsets of significant, persistent decreases in creep rates have occurred at several sites 12 months or more before the times of moderate earthquakes. A 44-month retardation before the 1979 ML=5.9 Coyote Lake earthquake on the Calaveras fault was recorded at the Shore Road creepmeter site 10 km northwest of Hollister. Creep retardation on the San Andreas fault near San Juan Bautista has been evident in records from one creepmeter site for

  14. Post-1906 stress recovery of the San Andreas fault system calculated from three-dimensional finite element analysis (United States)

    Parsons, T.


    The M = 7.8 1906 San Francisco earthquake cast a stress shadow across the San Andreas fault system, inhibiting other large earthquakes for at least 75 years. The duration of the stress shadow is a key question in San Francisco Bay area seismic hazard assessment. This study presents a three-dimensional (3-D) finite element simulation of post-1906 stress recovery. The model reproduces observed geologic slip rates on major strike-slip faults and produces surface velocity vectors comparable to geodetic measurements. Fault stressing rates calculated with the finite element model are evaluated against numbers calculated using deep dislocation slip. In the finite element model, tectonic stressing is distributed throughout the crust and upper mantle, whereas tectonic stressing calculated with dislocations is focused mostly on faults. In addition, the finite element model incorporates postseismic effects such as deep afterslip and viscoelastic relaxation in the upper mantle. More distributed stressing and postseismic effects in the finite element model lead to lower calculated tectonic stressing rates and longer stress shadow durations (17-74 years compared with 7-54 years). All models considered indicate that the 1906 stress shadow was completely erased by tectonic loading no later than 1980. However, the stress shadow still affects present-day earthquake probability. Use of stressing rate parameters calculated with the finite element model yields a 7-12% reduction in 30-year probability caused by the 1906 stress shadow as compared with calculations not incorporating interactions. The aggregate interaction-based probability on selected segments (not including the ruptured San Andreas fault) is 53-70% versus the noninteraction range of 65-77%.

  15. SAFOD Penetrates the San Andreas Fault

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    Mark D. Zoback


    Full Text Available SAFOD, the San Andreas Fault Observatory at Depth (Fig. 1, completed an important milestone in July 2005 by drilling through the San Andreas Fault at seismogenic depth. SAFOD is one of three major components of EarthScope, a U.S. National Science Foundation (NSF initiative being conducted in collaboration with the U.S. Geological Survey (USGS. The International Continental Scientific DrillingProgram (ICDP provides engineering and technical support for the project as well as online access to project data and information ( In 2002, the ICDP, the NSF, and the USGS provided funding for a pilot hole project at the SAFOD site. Twenty scientifi c papers summarizing the results of the pilot hole project as well as pre-SAFOD site characterization studies were published in Geophysical Research Letters (Vol.31, Nos. 12 and 15, 2004.

  16. Synthetic seismicity for the San Andreas fault

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    S. N. Ward


    Full Text Available Because historical catalogs generally span only a few repetition intervals of major earthquakes, they do not provide much constraint on how regularly earthquakes recur. In order to obtain better recurrence statistics and long-term probability estimates for events M ? 6 on the San Andreas fault, we apply a seismicity model to this fault. The model is based on the concept of fault segmentation and the physics of static dislocations which allow for stress transfer between segments. Constraints are provided by geological and seismological observations of segment lengths, characteristic magnitudes and long-term slip rates. Segment parameters slightly modified from the Working Group on California Earthquake Probabilities allow us to reproduce observed seismicity over four orders of magnitude. The model yields quite irregular earthquake recurrence patterns. Only the largest events (M ? 7.5 are quasi-periodic; small events cluster. Both the average recurrence time and the aperiodicity are also a function of position along the fault. The model results are consistent with paleoseismic data for the San Andreas fault as well as a global set of historical and paleoseismic recurrence data. Thus irregular earthquake recurrence resulting from segment interaction is consistent with a large range of observations.

  17. Geophysical investigation of the fault architecture of the San Andreas - Calaveras Fault junction in central California (United States)

    Watt, J. T.; Jachens, R. C.; Graymer, R. W.; Ponce, D. A.; Simpson, R. W.


    We use potential-field modeling, surface geologic mapping, and relocated seismicity (Waldhauser and Schaff, 2008) to investigate the three-dimensional structure of the San Andreas-Calaveras Fault junction to gain insight into regional tectonics, fault kinematics, and seismic hazards. South of the San Francisco Bay area, the San Andreas and Hayward-Calaveras-Paicines fault zones join to become a single San Andreas Fault. The Paicines fault is the southern-most extension of the Calaveras fault zone. At the surface, the San Andreas and Paicines faults are both creeping (Ryder and Burgmann, 2008), and parallel each other for about 65 km, separated by only 2-3 km. Approximately 175 km of slip has been transferred from the San Andreas onto the Calaveras-Hayward fault system in this area. The current geometry of this junction is not kinematically sustainable without deformation and/or slip on additional fault surfaces in the region (Burford and Savage, 1972). Dislocation modeling involving slip on detachment faults rather than on only strike-slip faults better predicts observations of geodetic displacements in the junction area, signifying the possible existence of active horizontal or dipping structures (Burgmann, 1997). Geophysical evidence suggests that the San Andreas and Paicines faults dip away from eachother within the fault junction, reflecting regional compression across the junction, and we identify multiple structures that may transfer slip through this complex structural zone. Geophysical modeling and relocated seismicity show the San Andreas fault dips steeply to the southwest within the join. Interpretation of relocated seismicity indicates multiple dipping and sub-horizontal faults. In particular, along the northern and southern portions of the junction, northeast-dipping alignments of hypocenters, if projected to the surface, correlate with the trace of the Paicines fault. In addition, we identify a laterally extensive magnetic body 1-8 km below the

  18. Mafic and ultramafic inclusions along the San Andreas Fault System: their geophysical character and effect on earthquake behavior, California, USA (United States)

    Ponce, D. A.; Langenheim, V. E.; Jachens, R. C.; Hildenbrand, T. G.


    Mafic and ultramafic rocks along the San Andreas Fault System (SAFS) influence earthquake processes where their geologic setting often provides information on the tectonic evolution of these large-scale strike-slip faults. In the northern part of the SAFS, along the Hayward Fault (HF), inversion of gravity and magnetic data indicate that seismicity avoids the interior of a large gabbro body and mechanical models may be able to explain how this massive mafic block influences the distribution of stress. Aftershocks of the M6.7 1989 Loma Prieta earthquake are also spatially related to the distribution of a gabbro body, clustering along the SAF and terminating at the NW end of the gabbro body where it abuts the fault surface. Based on geophysical modeling and a three-dimensional view of the subsurface geology and seismicity, aftershocks do not occur in the interior of the buried gabbro body. In the southern part of the SAFS, aftershocks and ruptures of the M7.1 1999 Hector Mine and M7.3 1992 Landers earthquakes avoid the interior of a Jurassic diorite that extends to depths of approximately 15 km and was probably an important influence on the rupture geometry of the these earthquakes. Seismicity prior to the Landers earthquake also tend to avoid the diorite, suggesting that it affects strain distribution. The San Jacinto Fault (SJF), a discontinuity within the Peninsular Ranges batholith (PRB), separates mafic, dense, and magnetic rocks of the western PRB from more felsic, less dense, and weakly magnetic rocks of the eastern PRB. The geophysical gradients do not cross the SJF zone, but instead bend to the northwest and coincide with the fault zone. Because emplacement of the PRB presumably welded across this older crustal boundary, the SJF zone probably developed along the favorably oriented margin of the dense, stronger western PRB. Two historical M6.7 earthquakes may have nucleated along the PRB discontinuity suggesting that the PRB may continue to affect how strain

  19. Deep-water turbidites as Holocene earthquake proxies: the Cascadia subduction zone and Northern San Andreas Fault systems

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    J. E. Johnson


    Full Text Available New stratigraphic evidence from the Cascadia margin demonstrates that 13 earthquakes ruptured the margin from Vancouver Island to at least the California border following the catastrophic eruption of Mount Mazama. These 13 events have occurred with an average repeat time of ?? 600 years since the first post-Mazama event ?? 7500 years ago. The youngest event ?? 300 years ago probably coincides with widespread evidence of coastal subsidence and tsunami inundation in buried marshes along the Cascadia coast. We can extend the Holocene record to at least 9850 years, during which 18 events correlate along the same region. The pattern of repeat times is consistent with the pattern observed at most (but not all localities onshore, strengthening the contention that both were produced by plate-wide earthquakes. We also observe that the sequence of Holocene events in Cascadia may contain a repeating pattern, a tantalizing look at what may be the long-term behavior of a major fault system. Over the last ?? 7500 years, the pattern appears to have repeated at least three times, with the most recent A.D. 1700 event being the third of three events following a long interval of 845 years between events T4 and T5. This long interval is one that is also recognized in many of the coastal records, and may serve as an anchor point between the offshore and onshore records. Similar stratigraphic records are found in two piston cores and one box core from Noyo Channel, adjacent to the Northern San Andreas Fault, which show a cyclic record of turbidite beds, with thirty- one turbidite beds above a Holocene/.Pleistocene faunal «datum». Thus far, we have determined ages for 20 events including the uppermost 5 events from these cores. The uppermost event returns a «modern» age, which we interpret is likely the 1906 San Andreas earthquake. The penultimate event returns an intercept age of A.D. 1664 (2 ?? range 1505- 1822. The third event and fourth event

  20. Using surface creep rate to infer fraction locked for sections of the San Andreas fault system in northern California from alignment array and GPS data (United States)

    Lienkaemper, James J.; McFarland, Forrest S.; Simpson, Robert W.; Caskey, S. John


    Surface creep rate, observed along five branches of the dextral San Andreas fault system in northern California, varies considerably from one section to the next, indicating that so too may the depth at which the faults are locked. We model locking on 29 fault sections using each section’s mean long‐term creep rate and the consensus values of fault width and geologic slip rate. Surface creep rate observations from 111 short‐range alignment and trilateration arrays and 48 near‐fault, Global Positioning System station pairs are used to estimate depth of creep, assuming an elastic half‐space model and adjusting depth of creep iteratively by trial and error to match the creep observations along fault sections. Fault sections are delineated either by geometric discontinuities between them or by distinctly different creeping behaviors. We remove transient rate changes associated with five large (M≥5.5) regional earthquakes. Estimates of fraction locked, the ratio of moment accumulation rate to loading rate, on each section of the fault system provide a uniform means to inform source parameters relevant to seismic‐hazard assessment. From its mean creep rates, we infer the main branch (the San Andreas fault) ranges from only 20%±10% locked on its central creeping section to 99%–100% on the north coast. From mean accumulation rates, we infer that four urban faults appear to have accumulated enough seismic moment to produce major earthquakes: the northern Calaveras (M 6.8), Hayward (M 6.8), Rodgers Creek (M 7.1), and Green Valley (M 7.1). The latter three faults are nearing or past their mean recurrence interval.

  1. Chemical controls on fault behavior: weakening of serpentinite sheared against quartz-bearing rocks and its significance for fault creep in the San Andreas system (United States)

    Moore, Diane E.; Lockner, David A.


    The serpentinized ultramafic rocks found in many plate-tectonic settings commonly are juxtaposed against crustal rocks along faults, and the chemical contrast between the rock types potentially could influence the mechanical behavior of such faults. To investigate this possibility, we conducted triaxial experiments under hydrothermal conditions (200-350°C), shearing serpentinite gouge between forcing blocks of granite or quartzite. In an ultramafic chemical environment, the coefficient of friction, µ, of lizardite and antigorite serpentinite is 0.5-0.6, and µ increases with increasing temperature over the tested range. However, when either lizardite or antigorite serpentinite is sheared against granite or quartzite, strength is reduced to µ ~ 0.3, with the greatest strength reductions at the highest temperatures (temperature weakening) and slowest shearing rates (velocity strengthening). The weakening is attributed to a solution-transfer process that is promoted by the enhanced solubility of serpentine in pore fluids whose chemistry has been modified by interaction with the quartzose wall rocks. The operation of this process will promote aseismic slip (creep) along serpentinite-bearing crustal faults at otherwise seismogenic depths. During short-term experiments serpentine minerals reprecipitate in low-stress areas, whereas in longer experiments new Mg-rich phyllosilicates crystallize in response to metasomatic exchanges across the serpentinite-crustal rock contact. Long-term shear of serpentinite against crustal rocks will cause the metasomatic mineral assemblages, which may include extremely weak minerals such as saponite or talc, to play an increasingly important role in the mechanical behavior of the fault. Our results may explain the distribution of creep on faults in the San Andreas system.

  2. Long-term rates and the depth extent of fault creep along the San Andreas Fault system in northern California from alinement arrays and GPS data (United States)

    Lienkaemper, J. J.; McFarland, F. S.; Simpson, R. W.; Caskey, J.


    The dextral San Andreas Fault system (SAFS) in northern California comprises five branches that exhibit considerable variation in the amount and spatial extent of aseismic release or creep. We estimate the depth extent of creep with a forward elastic model using the algorithms of Okada (1992) and boundary value dislocation solutions for creep rate and depth of creeping patches. For purposes of analysis we label branches, from west to east: A (San Gregorio), B (San Andreas), C (Calaveras-Hayward-Rodgers Creek-Maacama), D (Northern Calaveras-Green Valley-Bartlett Springs) and E (Greenville. Since the 1960s alinement arrays have provided one of the most accurate means to estimate the long-term creep rate and these rates have been reasonably well determined for much of the San Francisco Bay area (SFBA) southward. Over the past decade we have been installing alinement arrays along the more remote faults, especially northward of the SFBA, to monitor the extent of creep on branches C and D. We currently monitor about 80 such arrays throughout the northern SAFS. To analyze the depth extent of creep over the entire system, we model 30 fault sections on these five branches, delineated either by geometric discontinuities between them or by distinctly different creeping behaviors. We have removed any significant transient rate changes imposed by large regional earthquakes. We use crustal velocities determined for global-positioning station pairs of survey mode and continuous (SGPS, CGPS or mixed pairs) that are located near each fault to provide additional constraint on average creep rates. We estimate the mean depth of creep from the mean observed surface creep rate for each section and the rate uncertainty allows estimation of a depth uncertainty. Uncertainties are generally much higher where only five years or less of alinement array data are available, but in some cases the addition of CGPS or multiple SGPS station pairs has been essential for a more complete evaluation of

  3. Structure and mechanics of the San Andreas-San Gregorio fault junction, San Francisco, California (United States)

    Parsons, Tom; Bruns, Terry R.; Sliter, Ray


    The right-lateral San Gregorio and San Andreas faults meet west of the Golden Gate near San Francisco. Coincident seismic reflection and refraction profiling across the San Gregorio and San Andreas faults south of their junction shows the crust between them to have formed shallow extensional basins that are dissected by parallel strike-slip faults. We employ a regional finite element model to investigate the long-term consequences of the fault geometry. Over the course of 2-3 m.y. of slip on the San Andreas-San Gregorio fault system, elongated extensional basins are predicted to form between the two faults. An additional consequence of the fault geometry is that the San Andreas fault is expected to have migrated eastward relative to the San Gregorio fault. We thus propose a model of eastward stepping right-lateral fault formation to explain the observed multiple fault strands and depositional basins. The current manifestation of this process might be the observed transfer of slip from the San Andreas fault east to the Golden Gate fault.

  4. Isotopic evidence for the infiltration of mantle and metamorphic CO2-H2O fluids from below in faulted rocks from the San Andreas Fault System

    Energy Technology Data Exchange (ETDEWEB)

    Pili, E.; Kennedy, B.M.; Conrad, M.E.; Gratier, J.-P.


    To characterize the origin of the fluids involved in the San Andreas Fault (SAF) system, we carried out an isotope study of exhumed faulted rocks from deformation zones, vein fillings and their hosts and the fluid inclusions associated with these materials. Samples were collected from segments along the SAF system selected to provide a depth profile from upper to lower crust. In all, 75 samples from various structures and lithologies from 13 localities were analyzed for noble gas, carbon, and oxygen isotope compositions. Fluid inclusions exhibit helium isotope ratios ({sup 3}He/{sup 4}He) of 0.1-2.5 times the ratio in air, indicating that past fluids percolating through the SAF system contained mantle helium contributions of at least 35%, similar to what has been measured in present-day ground waters associated with the fault (Kennedy et al., 1997). Calcite is the predominant vein mineral and is a common accessory mineral in deformation zones. A systematic variation of C- and O-isotope compositions of carbonates from veins, deformation zones and their hosts suggests percolation by external fluids of similar compositions and origin with the amount of fluid infiltration increasing from host rocks to vein to deformation zones. The isotopic trend observed for carbonates in veins and deformation zones follows that shown by carbonates in host limestones, marbles, and other host rocks, increasing with increasing contribution of deep metamorphic crustal volatiles. At each crustal level, the composition of the infiltrating fluids is thus buffered by deeper metamorphic sources. A negative correlation between calcite {delta}{sup 13}C and fluid inclusion {sup 3}He/{sup 4}He is consistent with a mantle origin for a fraction of the infiltrating CO{sub 2}. Noble gas and stable isotope systematics show consistent evidence for the involvement of mantle-derived fluids combined with infiltration of deep metamorphic H{sub 2}O and CO{sub 2} in faulting, supporting the involvement of

  5. The San Andreas fault experiment. [gross tectonic plates relative velocity (United States)

    Smith, D. E.; Vonbun, F. O.


    A plan was developed during 1971 to determine gross tectonic plate motions along the San Andreas Fault System in California. Knowledge of the gross motion along the total fault system is an essential component in the construction of realistic deformation models of fault regions. Such mathematical models will be used in the future for studies which will eventually lead to prediction of major earthquakes. The main purpose of the experiment described is the determination of the relative velocity of the North American and the Pacific Plates. This motion being so extremely small, cannot be measured directly but can be deduced from distance measurements between points on opposite sites of the plate boundary taken over a number of years.

  6. New insights on stress rotations from a forward regional model of the San Andreas fault system near its Big Bend in southern California (United States)

    Fitzenz, D.D.; Miller, S.A.


    Understanding the stress field surrounding and driving active fault systems is an important component of mechanistic seismic hazard assessment. We develop and present results from a time-forward three-dimensional (3-D) model of the San Andreas fault system near its Big Bend in southern California. The model boundary conditions are assessed by comparing model and observed tectonic regimes. The model of earthquake generation along two fault segments is used to target measurable properties (e.g., stress orientations, heat flow) that may allow inferences on the stress state on the faults. It is a quasi-static model, where GPS-constrained tectonic loading drives faults modeled as mostly sealed viscoelastic bodies embedded in an elastic half-space subjected to compaction and shear creep. A transpressive tectonic regime develops southwest of the model bend as a result of the tectonic loading and migrates toward the bend because of fault slip. The strength of the model faults is assessed on the basis of stress orientations, stress drop, and overpressures, showing a departure in the behavior of 3-D finite faults compared to models of 1-D or homogeneous infinite faults. At a smaller scale, stress transfers from fault slip transiently induce significant perturbations in the local stress tensors (where the slip profile is very heterogeneous). These stress rotations disappear when subsequent model earthquakes smooth the slip profile. Maps of maximum absolute shear stress emphasize both that (1) future models should include a more continuous representation of the faults and (2) that hydrostatically pressured intact rock is very difficult to break when no material weakness is considered. Copyright 2004 by the American Geophysical Union.

  7. High Resolution Seismic Imaging of Fault Zones: Methods and Examples From The San Andreas Fault (United States)

    Catchings, R. D.; Rymer, M. J.; Goldman, M.; Prentice, C. S.; Sickler, R. R.; Criley, C.


    Seismic imaging of fault zones at shallow depths is challenging. Conventional seismic reflection methods do not work well in fault zones that consist of non-planar strata or that have large variations in velocity structure, two properties that occur in most fault zones. Understanding the structure and geometry of fault zones is important to elucidate the earthquake hazard associated with fault zones and the barrier effect that faults impose on subsurface fluid flow. In collaboration with the San Francisco Public Utilities Commission (SFPUC) at San Andreas Lake on the San Francisco peninsula, we acquired combined seismic P-wave and S-wave reflection, refraction, and guided-wave data to image the principal strand of the San Andreas Fault (SAF) that ruptured the surface during the 1906 San Francisco earthquake and additional fault strands east of the rupture. The locations and geometries of these fault strands are important because the SFPUC is seismically retrofitting the Hetch Hetchy water delivery system, which provides much of the water for the San Francisco Bay area, and the delivery system is close to the SAF at San Andreas Lake. Seismic reflection images did not image the SAF zone well due to the brecciated bedrock, a lack of layered stratigraphy, and widely varying velocities. Tomographic P-wave velocity images clearly delineate the fault zone as a low-velocity zone at about 10 m depth in more competent rock, but due to soil saturation above the rock, the P-waves do not clearly image the fault strands at shallower depths. S-wave velocity images, however, clearly show a diagnostic low-velocity zone at the mapped 1906 surface break. To image the fault zone at greater depths, we utilized guided waves, which exhibit high amplitude seismic energy within fault zones. The guided waves appear to image the fault zone at varying depths depending on the frequency of the seismic waves. At higher frequencies (~30 to 40 Hz), the guided waves show strong amplification at the

  8. A Case for Historic Joint Rupture of the San Andreas and San Jacinto Faults (United States)

    Lozos, J.


    The ~M7.5 southern California earthquake of 8 December 1812 ruptured the San Andreas Fault from Cajon Pass to at least as far north as Pallet Creek (Biasi et al., 2002). The 1812 rupture has also been identified in trenches at Burro Flats to the south (Yule and Howland, 2001). However, the lack of a record of 1812 at Plunge Creek, between Cajon Pass and Burro Flats (McGill et al., 2002), complicates the interpretation of this event as a straightforward San Andreas rupture. Paleoseismic records of a large early 19th century rupture on the northern San Jacinto Fault (Onderdonk et al., 2013; Kendrick and Fumal, 2005) allow for alternate interpretations of the 1812 earthquake. I use dynamic rupture modeling on the San Andreas-San Jacinto junction to determine which rupture behaviors produce slip patterns consistent with observations of the 1812 event. My models implement realistic fault geometry, a realistic velocity structure, and stress orientations based on seismicity literature. Under these simple assumptions, joint rupture of the two faults is the most common behavior. My modeling rules out a San Andreas-only rupture that is consistent with the data from the 1812 earthquake, and also shows that single fault events are unable to match the average slip per event for either fault. The choice of nucleation point affects the details of rupture directivity and slip distribution, but not the first order result that multi-fault rupture is the preferred behavior. While it cannot be definitively said that joint San Andreas-San Jacinto rupture occurred in 1812, these results are consistent with paleoseismic and historic data. This has implications for the possibility of future multi-fault rupture within the San Andreas system, as well as for interpretation of other paleoseismic events in regions of complex fault interactions.

  9. San Andreas-sized Strike-slip Fault on Europa (United States)


    subsequent tidal stress causes it to move lengthwise in one direction. Then tidal forces close the fault again, preventing the area from moving back to its original position. Daily tidal cycles produce a steady accumulation of lengthwise offset motions. Here on Earth, unlike Europa, large strike-slip faults like the San Andreas are set in motion by plate tectonic forces. North is to the top of the picture and the sun illuminates the surface from the top. The image, centered at 66 degrees south latitude and 195 degrees west longitude, covers an area approximately 300 by 203 kilometers(185 by 125 miles). The pictures were taken on September 26, 1998by Galileo's solid-state imaging system. This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL Background information and educational context for the images can be found at URL

  10. The Tectonics and the Strength of the San Andreas Fault (United States)

    Lavier, L. L.; Bennett, R.


    Contrary to what is inferred from laboratory experiments, the average shear stress supported by the San Andreas fault is likely much less than 100 MPa. Heat flow measurements, stress orientation and shear stress magnitude measurements mostly argue for a very weak fault with an average shear stress lower than 20 MPa or an apparent coefficient of friction less than 0.1. It has been proposed that most of this difference can be explained by heat dissipation by fluid circulation around the fault. However, some workers have shown that with reasonable parameters for fluid flow in and around the fault the strength of the fault remains very weak. We evaluate 2.5 D numerical models of the formation and evolution of the San Andreas Fault zone. We explore a wide range of possible bottom and side boundary conditions to understand their potential effects on the apparent strength of a strike slip-fault. In particular, we consider the effects of a small amount of localized basal traction on one side of the fault. We use the numerical models to simulate partitioning of deformation between thrust and strike-slip faulting constrained by geodetic measurement of fault perpendicular convergence. The strength of the model San Andreas fault is chosen to be consistent with a Mohr-Coulomb failure mechanism for a strong fault consistent with Byerlee's rule. Wrench dominated deformation is driven from the Pacific plate side of the San Andreas fault, and convergence is driven by localized basal traction on the North America side. The rheology assumed in the experiments allows for the spontaneous formation of faults with a Mohr-coulomb plastic formulation in the upper crust, as well as viscous flow in the lower crust. The numerical calculations are performed with an extended version of the numerical code PARAVOZ. We find that a combination of loading from the side and the bottom as well as decoupling between the upper crustal and lower crustal deformation can decrease the shear stresses on the

  11. Geomorphic evidence of active tectonics in the San Gorgonio Pass region of the San Andreas Fault system: an example of discovery-based research in undergraduate teaching (United States)

    Reinen, L. A.; Yule, J. D.


    Student-conducted research in courses during the first two undergraduate years can increase learning and improve student self-confidence in scientific study, and is recommended for engaging and retaining students in STEM fields (PCAST, 2012). At Pomona College, incorporating student research throughout the geology curriculum tripled the number of students conducting research prior to their senior year that culminated in a professional conference presentation (Reinen et al., 2006). Here we present an example of discovery-based research in Neotectonics, a second-tier course predominantly enrolling first-and second-year students; describe the steps involved in the four week project; and discuss early outcomes of student confidence, engagement and retention. In the San Gorgonio Pass region (SGPR) in southern California, the San Andreas fault undergoes a transition from predominantly strike-slip to a complex system of faults with significant dip-slip, resulting in diffuse deformation and raising the question of whether a large earthquake on the San Andreas could propagate through the region (Yule, 2009). In spring 2014, seven students in the Neotectonics course conducted original research investigating quantifiable geomorphic evidence of tectonic activity in the SGPR. Students addressed questions of [1] unequal uplift in the San Bernardino Mountains, [2] fault activity indicated by stream knick points, [3] the role of fault style on mountain front sinuosity, and [4] characteristic earthquake slip determined via fault scarp degradation models. Students developed and revised individual projects, collaborated with each other on methods, and presented results in a public forum. A final class day was spent reviewing the projects and planning future research directions. Pre- and post-course surveys show increases in students' self-confidence in the design, implementation, and presentation of original scientific inquiries. 5 of 6 eligible students participated in research the

  12. Overview of the Southern San Andreas Fault Model (United States)

    Weldon, Ray J.; Biasi, Glenn P.; Wills, Chris J.; Dawson, Timothy E.


    This appendix summarizes the data and methodology used to generate the source model for the southern San Andreas fault. It is organized into three sections, 1) a section by section review of the geological data in the format of past Working Groups, 2) an overview of the rupture model, and 3) a manuscript by Biasi and Weldon (in review Bulletin of the Seismological Society of America) that describes the correlation methodology that was used to help develop the ?geologic insight? model. The goal of the Biasi and Weldon methodology is to quantify the insight that went into developing all A faults; as such it is in concept consistent with all other A faults but applied in a more quantitative way. The most rapidly slipping fault and the only known source of M~8 earthquakes in southern California is the San Andreas fault. As such it plays a special role in the seismic hazard of California, and has received special attention in the current Working Group. The underlying philosophy of the current Working Group is to model the recurrence behavior of large, rapidly slipping faults like the San Andreas from observed data on the size, distribution and timing of past earthquakes with as few assumptions about underlying recurrence behavior as possible. In addition, we wish to carry the uncertainties in the data and the range of reasonable extrapolations from the data to the final model. To accomplish this for the Southern San Andreas fault we have developed an objective method to combine all of the observations of size, timing, and distribution of past earthquakes into a comprehensive set of earthquake scenarios that each represent a possible history of earthquakes for the past ~1400 years. The scenarios are then ranked according to their overall consistency with the data and then the frequencies of all of the ruptures permitted by the current Working Group?s segmentation model are calculated. We also present 30-yr conditional probabilities by segment and compare to previous

  13. FE modeling of present day tectonic stress along the San Andreas Fault zone


    Koirala, Matrika Prasad; Hauashi, Daigoro; 林, 大五郎


    F E modeling under plane stress condition is used to analyze the state of stress in and around the San Andreas Fault (SAF) System taking whole area of California. In this study we mainly focus on the state of stress at the general seismogenic depth of 12 km, imposing elastic rheology. The purpose of the present study is to simulate the regional stress field, displacement vectors and failures. Stress perturbation due to major fault, its geometry and major branches are analyzed. Depthwise varia...

  14. Fine-scale delineation of the location of and relative ground shaking within the San Andreas Fault zone at San Andreas Lake, San Mateo County, California (United States)

    Catchings, R.D.; Rymer, M.J.; Goldman, M.R.; Prentice, C.S.; Sickler, R.R.


    The San Francisco Public Utilities Commission is seismically retrofitting the water delivery system at San Andreas Lake, San Mateo County, California, where the reservoir intake system crosses the San Andreas Fault (SAF). The near-surface fault location and geometry are important considerations in the retrofit effort. Because the SAF trends through highly distorted Franciscan mélange and beneath much of the reservoir, the exact trace of the 1906 surface rupture is difficult to determine from surface mapping at San Andreas Lake. Based on surface mapping, it also is unclear if there are additional fault splays that extend northeast or southwest of the main surface rupture. To better understand the fault structure at San Andreas Lake, the U.S. Geological Survey acquired a series of seismic imaging profiles across the SAF at San Andreas Lake in 2008, 2009, and 2011, when the lake level was near historical lows and the surface traces of the SAF were exposed for the first time in decades. We used multiple seismic methods to locate the main 1906 rupture zone and fault splays within about 100 meters northeast of the main rupture zone. Our seismic observations are internally consistent, and our seismic indicators of faulting generally correlate with fault locations inferred from surface mapping. We also tested the accuracy of our seismic methods by comparing our seismically located faults with surface ruptures mapped by Schussler (1906) immediately after the April 18, 1906 San Francisco earthquake of approximate magnitude 7.9; our seismically determined fault locations were highly accurate. Near the reservoir intake facility at San Andreas Lake, our seismic data indicate the main 1906 surface rupture zone consists of at least three near-surface fault traces. Movement on multiple fault traces can have appreciable engineering significance because, unlike movement on a single strike-slip fault trace, differential movement on multiple fault traces may exert compressive and

  15. Zoogeography of the San Andreas Fault system: Great Pacific Fracture Zones correspond with spatially concordant phylogeographic boundaries in western North America. (United States)

    Gottscho, Andrew D


    The purpose of this article is to provide an ultimate tectonic explanation for several well-studied zoogeographic boundaries along the west coast of North America, specifically, along the boundary of the North American and Pacific plates (the San Andreas Fault system). By reviewing 177 references from the plate tectonics and zoogeography literature, I demonstrate that four Great Pacific Fracture Zones (GPFZs) in the Pacific plate correspond with distributional limits and spatially concordant phylogeographic breaks for a wide variety of marine and terrestrial animals, including invertebrates, fish, amphibians, reptiles, birds, and mammals. These boundaries are: (1) Cape Mendocino and the North Coast Divide, (2) Point Conception and the Transverse Ranges, (3) Punta Eugenia and the Vizcaíno Desert, and (4) Cabo Corrientes and the Sierra Transvolcanica. However, discussion of the GPFZs is mostly absent from the zoogeography and phylogeography literature likely due to a disconnect between biologists and geologists. I argue that the four zoogeographic boundaries reviewed here ultimately originated via the same geological process (triple junction evolution). Finally, I suggest how a comparative phylogeographic approach can be used to test the hypothesis presented here.

  16. The Eastern California Shear Zone as the northward extension of the southern San Andreas Fault (United States)

    Thatcher, Wayne R.; Savage, James C.; Simpson, Robert W.


    Cluster analysis offers an agnostic way to organize and explore features of the current GPS velocity field without reference to geologic information or physical models using information only contained in the velocity field itself. We have used cluster analysis of the Southern California Global Positioning System (GPS) velocity field to determine the partitioning of Pacific-North America relative motion onto major regional faults. Our results indicate the large-scale kinematics of the region is best described with two boundaries of high velocity gradient, one centered on the Coachella section of the San Andreas Fault and the Eastern California Shear Zone and the other defined by the San Jacinto Fault south of Cajon Pass and the San Andreas Fault farther north. The ~120 km long strand of the San Andreas between Cajon Pass and Coachella Valley (often termed the San Bernardino and San Gorgonio sections) is thus currently of secondary importance and carries lesser amounts of slip over most or all of its length. We show these first order results are present in maps of the smoothed GPS velocity field itself. They are also generally consistent with currently available, loosely bounded geologic and geodetic fault slip rate estimates that alone do not provide useful constraints on the large-scale partitioning we show here. Our analysis does not preclude the existence of smaller blocks and more block boundaries in Southern California. However, attempts to identify smaller blocks along and adjacent to the San Gorgonio section were not successful.

  17. The San Andreas Fault and a Strike-slip Fault on Europa (United States)


    be filled in mostly by sedimentary and erosional material deposited from above. Comparisons between faults on Europa and Earth may generate ideas useful in the study of terrestrial faulting. One theory is that fault motion on Europa is induced by the pull of variable daily tides generated by Jupiter's gravitational tug on Europa. The tidal tension opens the fault; subsequent tidal stress causes it to move lengthwise in one direction. Then the tidal forces close the fault up again. This prevents the area from moving back to its original position. If it moves forward with the next daily tidal cycle, the result is a steady accumulation of these lengthwise offset motions. Unlike Europa, here on Earth, large strike-slip faults such as the San Andreas are set in motion not by tidal pull, but by plate tectonic forces from the planet's mantle. North is to the top of the picture. The Earth picture (left) shows a LandSat Thematic Mapper image acquired in the infrared (1.55 to 1.75 micrometers) by LandSat5 on Friday, October 20th 1989 at 10:21 am. The original resolution was 28.5 meters per picture element. The Europa picture (right)is centered at 66 degrees south latitude and 195 degrees west longitude. The highest resolution frames, obtained at 40 meters per picture element with a spacecraft range of less than 4200 kilometers (2600 miles), are set in the context of lower resolution regional frames obtained at 200 meters per picture element and a range of 22,000 kilometers (13,600 miles). The images were taken on September 26, 1998 by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft. The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL Background information and educational context for the images can be found at URL HTTP://

  18. Deep permeability of the San Andreas Fault from San Andreas Fault Observatory at Depth (SAFOD) core samples (United States)

    Morrow, Carolyn A.; Lockner, David A.; Moore, Diane E.; Hickman, Stephen H.


    The San Andreas Fault Observatory at Depth (SAFOD) scientific borehole near Parkfield, California crosses two actively creeping shear zones at a depth of 2.7 km. Core samples retrieved from these active strands consist of a foliated, Mg-clay-rich gouge containing porphyroclasts of serpentinite and sedimentary rock. The adjacent damage zone and country rocks are comprised of variably deformed, fine-grained sandstones, siltstones, and mudstones. We conducted laboratory tests to measure the permeability of representative samples from each structural unit at effective confining pressures, Pe up to the maximum estimated in situ Pe of 120 MPa. Permeability values of intact samples adjacent to the creeping strands ranged from 10−18 to 10−21 m2 at Pe = 10 MPa and decreased with applied confining pressure to 10−20–10−22 m2 at 120 MPa. Values for intact foliated gouge samples (10−21–6 × 10−23 m2 over the same pressure range) were distinctly lower than those for the surrounding rocks due to their fine-grained, clay-rich character. Permeability of both intact and crushed-and-sieved foliated gouge measured during shearing at Pe ≥ 70 MPa ranged from 2 to 4 × 10−22 m2 in the direction perpendicular to shearing and was largely insensitive to shear displacement out to a maximum displacement of 10 mm. The weak, actively-deforming foliated gouge zones have ultra-low permeability, making the active strands of the San Andreas Fault effective barriers to cross-fault fluid flow. The low matrix permeability of the San Andreas Fault creeping zones and adjacent rock combined with observations of abundant fractures in the core over a range of scales suggests that fluid flow outside of the actively-deforming gouge zones is probably fracture dominated.

  19. Loading of the San Andreas fault by flood-induced rupture of faults beneath the Salton Sea (United States)

    Brothers, Daniel; Kilb, Debi; Luttrell, Karen; Driscoll, Neal W.; Kent, Graham


    The southern San Andreas fault has not experienced a large earthquake for approximately 300 years, yet the previous five earthquakes occurred at ~180-year intervals. Large strike-slip faults are often segmented by lateral stepover zones. Movement on smaller faults within a stepover zone could perturb the main fault segments and potentially trigger a large earthquake. The southern San Andreas fault terminates in an extensional stepover zone beneath the Salton Sea—a lake that has experienced periodic flooding and desiccation since the late Holocene. Here we reconstruct the magnitude and timing of fault activity beneath the Salton Sea over several earthquake cycles. We observe coincident timing between flooding events, stepover fault displacement and ruptures on the San Andreas fault. Using Coulomb stress models, we show that the combined effect of lake loading, stepover fault movement and increased pore pressure could increase stress on the southern San Andreas fault to levels sufficient to induce failure. We conclude that rupture of the stepover faults, caused by periodic flooding of the palaeo-Salton Sea and by tectonic forcing, had the potential to trigger earthquake rupture on the southern San Andreas fault. Extensional stepover zones are highly susceptible to rapid stress loading and thus the Salton Sea may be a nucleation point for large ruptures on the southern San Andreas fault.

  20. A Look Inside the San Andreas fault at Parkfield Through Vertical Seismic Profiling (United States)

    Chavarria, J.A.; Malin, P.; Catchings, R.D.; Shalev, E.


    The San Andreas Fault Observatory at Depth pilot hole is located on the southwestern side of the Parkfield San Andreas fault. This observatory includes a vertical seismic profiling (VSP) array. VSP seismograms from nearby micro-earthquakes contain signals between the P and S waves. These signals may be P and S waves scattered by the local geologic structure. The collected scattering points form planar surfaces that we interpret as the San Andreas fault and four other secondary faults. The scattering process includes conversions between P and S waves, the strengths of which suggest large contrasts in material properties, possibly indicating the presence of cracks or fluids.

  1. Vertical tectonic deformation associated with the San Andreas fault zone offshore of San Francisco, California (United States)

    Ryan, H. F.; Parsons, T.; Sliter, R. W.


    A new fault map of the shelf offshore of San Francisco, California shows that faulting occurs as a distributed shear zone that involves many fault strands with the principal displacement taken up by the San Andreas fault and the eastern strand of the San Gregorio fault zone. Structures associated with the offshore faulting show compressive deformation near where the San Andreas fault goes offshore, but deformation becomes extensional several km to the north off of the Golden Gate. Our new fault map serves as the basis for a 3-D finite element model that shows that the block between the San Andreas and San Gregorio fault zone is subsiding at a long-term rate of about 0.2-0.3 mm/yr, with the maximum subsidence occurring northwest of the Golden Gate in the area of a mapped transtensional basin. Although the long-term rates of vertical displacement primarily show subsidence, the model of coseismic deformation associated with the 1906 San Francisco earthquake indicates that uplift on the order of 10-15 cm occurred in the block northeast of the San Andreas fault. Since 1906, 5-6 cm of regional subsidence has occurred in that block. One implication of our model is that the transfer of slip from the San Andreas fault to a fault 5 km to the east, the Golden Gate fault, is not required for the area offshore of San Francisco to be in extension. This has implications for both the deposition of thick Pliocene-Pleistocene sediments (the Merced Formation) observed east of the San Andreas fault, and the age of the Peninsula segment of the San Andreas fault.

  2. Could lithospheric instability cause the San Andreas Fault to creep ? (United States)

    Le Pourhiet, L.; Saleeby, J.


    The Southern Sierra Nevada mountains range rapidly uplifted at ≈ 3.5 Ma simultaneously with a pulse of basaltic volcanism. Xenoliths recovered from volcanics indicate that the range lost a dense crustal root after the Miocene. The vertical motions and removal of the root have been linked to a fast seismic velocity anomaly that extends ≈ 200 km into the mantle but is offset to the west of the range. With visco-elasto-plastic thermo-mechanical numerical models, we have tested the influence of crustal strength on the kinematics of removal and on the amount of associated uplift. We find that delamination of the dense root is the most likely mechanism for gravitational instability to occur. In this class of models, the Great Valley deforms by elastic flexure in response to the load exerted by the delaminated root. We therefore explore the influence of the strength of the Great Valley on the wavelength of the flexure and complement 2D models by flexural 3D models. The study shows that for a Te=10 km, the flexural anomaly resulting from the drip pull outlines the limit between the area where the Quaternary sediments are found on-lapping or off-lapping the western flank of the Sierra. On the Western edge of the Sierra Nevada micro plate, the flexural anomaly crosses the San Andreas Fault. Where uplift is predicted Miocene strata are eroding, and where subsidence is predicted Quaternary sediments are at the surface. These geological limits also coincide with the limit of the creeping segment of the Fault. Geological evidence (especially fold kinematics) suggests that the extreme weakness of the San Andreas Fault in that area started during the Pliocene (~3 Ma). This timing also coincides with the rapid uplift of the Sierra Nevada. Simple coincidences or real mechanical link between these two anomalous behaviors? We will present and discuss how flexure could promote lithostatic fluid pressure in the depth range of 7 to 15 km along the creeping segment of the fault, and

  3. The San Andreas fault in the San Francisco Bay region, California: Structure and kinematics of a Young plate boundary (United States)

    Jachens, R.C.; Zoback, M.L.


    Recently acquired high-resolution aeromagnetic data delineate offset and/or truncated magnetic rock bodies of the Franciscan Complex that define the location and structure of, and total offset across, the San Andreas fault in the San Francisco Bay region. Two distinctive magnetic anomalies caused by ultramafic rocks and metabasalts east of, and truncated at, the San Andreas fault have clear counterparts west of the fault that indicate a total right-lateral offset of only 22 km on the Peninsula segment, the active strand that ruptured in 1906. The location of the Peninsula segment is well defined magnetically on the northern peninsula where it goes offshore, and can be traced along strike an additional ~6 km to the northwest. Just offshore from Lake Merced, the inferred fault trace steps right (northeast) 3 km onto a nearly parallel strand that can be traced magnetically northwest more than 20 km as the linear northeast edge of a magnetic block bounded by the San Andreas fault, the Pilarcitos fault, and the San Gregorio-Hosgri fault zone. This right-stepping strand, the Golden Gate segment, joins the eastern mapped trace of the San Andreas fault at Bolinas Lagoon and projects back onshore to the southeast near Lake Merced. Inversion of detailed gravity data on the San Francisco Peninsula reveals a 3 km wide basin situated between the two strands of the San Andreas fault, floored by Franciscan basement and filled with Plio-Quaternary sedimentary deposits of the Merced and Colma formations. The basin, ~1 km deep at the coast, narrows and becomes thinner to the southeast along the fault over a distance of ~12 km. The length, width, and location of the basin between the two strands are consistent with a pull-apart basin formed behind the right step in the right-lateral strike-slip San Andreas fault system and currently moving southeast with the North American plate. Slight nonparallelism of the two strands bounding the basin (implying a small component of convergence

  4. San Andreas Fault damage at SAFOD viewed with fault-guided waves (United States)

    Li, Yong-Gang; Malin, Peter E.


    Highly damaged rocks within the San Andreas fault zone at Parkfield form a low-velocity waveguide for seismic waves, giving rise to fault-guided waves. Prominent fault-guided waves have been observed at the San Andreas Fault Observatory at Depth (SAFOD) site, including a surface array across the fault zone and a borehole seismograph placed in the SAFOD well at a depth of ~2.7 km below ground. The resulting observations are modeled here using 3-D finite-difference methods. To fit the amplitude, frequency, and travel-time characteristics of the data, the models require a downward tapering, 30-40-m wide fault-core embedded in a 100-200-m wide jacket. Compared with the intact wall rocks, the core velocities are reduced by ~40% and jacket velocities by ~25%. Based on the depths of earthquakes generating guided waves, we estimate that the low-velocity waveguide along the fault at SAFOD extends at least to depths of ~7 km, more than twice the depth reported in pervious studies.

  5. Potential and limits of InSAR to characterize interseismic deformation independently of GPS data: Application to the southern San Andreas Fault system (United States)

    Chaussard, E.; Johnson, C. W.; Fattahi, H.; Bürgmann, R.


    The evaluation of long-wavelength deformation associated with interseismic strain accumulation traditionally relies on spatially sparse GPS measurements, or on high spatial-resolution InSAR velocity fields aligned to a GPS-based model. In this approach the InSAR contributes only short-wavelength deformation and the two data sets are dependent, thereby challenging the evaluation of the InSAR uncertainties and the justification of atmospheric corrections. Here we present an analysis using 7 years of Envisat InSAR data to characterize interseismic deformation along the southern San Andreas Fault (SAF) and the San Jacinto Fault (SJF) in southern California, where the SAF bifurcates onto the Mission Creek (MCF) and the Banning (BF) fault strands. We outline the processing steps for using InSAR alone to characterize both the short- and long-wavelength deformation, and evaluate the velocity field uncertainties with independent continuous GPS data. InSAR line-of-sight (LOS) and continuous GPS velocities agree within ˜1-2 mm/yr in the study area, suggesting that multiyear InSAR time series can be used to characterize interseismic deformation with a higher spatial resolution than GPS. We investigate with dislocation models the ability of this mean LOS velocity field to constrain fault slip rates and show that a single viewing geometry can help distinguish between different slip-rate scenarios on the SAF and SJF (˜35 km apart) but multiple viewing geometries are needed to differentiate slip on the MCF and BF (<12 km apart). Our results demonstrate that interseismic models of strain accumulation used for seismic hazards assessment would benefit from the consideration of InSAR mean velocity maps.

  6. Fault rocks from the SAFOD core samples : implications for weakening at shallow depths along the San Andreas Fault, California

    NARCIS (Netherlands)

    Holdsworth, R.E.; van Diggelen, E.W.E.; Spiers, C.J.; Bresser, J.H.P. de; Walker, R.J.; Bown, L.


    The drilling of a deep borehole across the actively creeping Parkfield segment of the San Andreas Fault Zone (SAFZ), California, and collection of core materials permit direct geological study of fault zone processes at 2–3 km depth. The three drill cores sample both host and fault rocks and pass th

  7. Abrupt along-strike change in tectonic style: San Andreas Fault zone, San Francisco Peninsula (United States)

    Zoback, Mary Lou; Jachens, Robert C.; Olson, Jean A.


    Seismicity and high-resolution aeromagnetic data are used to define an abrupt change from compressional to extensional tectonism within a 10- to 15-km-wide zone along the San Andreas fault on the San Francisco Peninsula and offshore from the Golden Gate. This 100-km-long section of the San Andreas fault includes the hypocenter of the Mw = 7.8 1906 San Francisco earthquake as well as the highest level of persistent microseismicity along that ˜470-km-long rupture. We define two distinct zones of deformation along this stretch of the fault using well-constrained relocations of all post-1969 earthquakes based a joint one-dimensional velocity/hypocenter inversion and a redetermination of focal mechanisms. The southern zone is characterized by thrust- and reverse-faulting focal mechanisms with NE trending P axes that indicate "fault-normal" compression in 7- to 10-km-wide zones of deformation on both sides of the San Andreas fault. A 1- to 2-km-wide vertical zone beneath the surface trace of the San Andreas is characterized by its almost complete lack of seismicity. The compressional deformation is consistent with the young, high topography of the Santa Cruz Mountains/Coast Ranges as the San Andreas fault makes a broad restraining left bend (˜10°) through the southernmost peninsula. A zone of seismic quiescence ˜15 km long separates this compressional zone to the south from a zone of combined normal-faulting and strike-slip-faulting focal mechanisms (including a ML = 5.3 earthquake in 1957) on the northernmost peninsula and offshore on the Golden Gate platform. Both linear pseudogravity gradients, calculated from the aeromagnetic data, and seismic reflection data indicate that the San Andreas fault makes an abrupt ˜3-km right step less than 5 km offshore in this northern zone. A similar right-stepping (dilatational) geometry is also observed for the subparallel San Gregorio fault offshore. Persistent seismicity and extensional tectonism occur within the San Andreas

  8. Flow and Chemistry Pulsations, Monterey: Implications for Stress Transient Modulations of Hydrologic and Geochemical Systems in the Greater San Andreas Fault Zone (United States)

    Brown, K. M.; Fueri, E.; Hilton, D. R.


    Submarine fluid venting at continental shelf and slope regions has been recognized over the past ten years as an important, yet under-studied process in marine science. Seeps are now known to be a general feature of the hydrogeology of many tectonically active continental margins. The eastern Pacific margin is characterized by a variety of tectonic settings (i.e. convergent and strike-slip) where active venting of fluids and gases has been documented. Reports include vents off Alaska, Costa Rica, Monterey Bay, Eel River basin, and Heceta Bay, OR. Indications of seismic tremor, linked to hydrologic transience in the offshore regions of subduction zones have recently been published elsewhere (see Brown et al, EPSL 2005). We now address here the varying nature of submarine fluid discharges in a San Andreas strike-slip setting. A key element of the proposed work is the combined multidisciplinary measurement of fluid flow, seep temperatures, and dissolved noble gases and chemistry of the Monterey seep sites at Extrovert Cliff. The seeps are situated close to several active strike-slip faults including the Monterey and San Gregorio fault zones. Initial results of 2 week deployments in 2004 of flow meters at Extravert Cliff indicated high flow rates and elevated seep temperatures that vary by as much as a factor of 2 on diurnal time scales with subtle changes over longer periods (>2 weeks). There are also indicative chemical signals of deeply sourced fluids that vary widely with time that show the following signals: 1) Elevated abundances of both mantle derived Helium (3He) as well as 4He and 40Ar of radiogenic crustal relevant trace element components; 2) Altered fluid chemistry (including, Ca Mg, Li and B); 3) The fluid temperature, flow rates, and gas chemistry, in particular, vary with time. We have both long-term and sub-diurnal variations in flow and temperature as well as the 3He/4He ratios, helium concentration, CO2 concentration and d13C values perhaps influenced

  9. The San Andreas Fault in the San Francisco Bay area, California: a geology fieldtrip guidebook to selected stops on public lands (United States)

    Stoffer, Philip W.


    This guidebook contains a series of geology fieldtrips with selected destinations along the San Andreas Fault in part of the region that experienced surface rupture during the Great San Francisco Earthquake of 1906. Introductory materials present general information about the San Andreas Fault System, landscape features, and ecological factors associated with faults in the South Bay, Santa Cruz Mountains, the San Francisco Peninsula, and the Point Reyes National Seashore regions. Trip stops include roadside areas and recommended hikes along regional faults and to nearby geologic and landscape features that provide opportunities to make casual observations about the geologic history and landscape evolution. Destinations include the sites along the San Andreas and Calaveras faults in the San Juan Bautista and Hollister region. Stops on public land along the San Andreas Fault in the Santa Cruz Mountains in Santa Clara and Santa Cruz counties include in the Loma Prieta summit area, Forest of Nicene Marks State Park, Lexington County Park, Sanborn County Park, Castle Rock State Park, and the Mid Peninsula Open Space Preserve. Destinations on the San Francisco Peninsula and along the coast in San Mateo County include the Crystal Springs Reservoir area, Mussel Rock Park, and parts of Golden Gate National Recreation Area, with additional stops associated with the San Gregorio Fault system at Montara State Beach, the James F. Fitzgerald Preserve, and at Half Moon Bay. Field trip destinations in the Point Reyes National Seashore and vicinity provide information about geology and character of the San Andreas Fault system north of San Francisco.

  10. Effects of Hayward fault interactions with the Rodgers Creek and San Andreas faults (United States)

    Parsons, T.; Geist, E.; Jachens, R.; Sliter, R.; Jaffe, B.


    Finite-element and crustal-structure models of the Hayward fault emphasize its position within a network of interacting faults, and indicate a number of expected influences from other faults. For example, a new structural cross section across San Pablo Bay in association with potential field maps allows us to map and model detailed interactions between the Hayward and Rodgers Creek faults. The two faults do not appear to connect at depth, and finite-element models indicate growing extensional stress in the stepover between the two faults. A model consequence of extensional stress in the stepover, combined with long-term interaction with the San Andreas fault, is normal-stress reduction (unclamping) of the north Hayward fault. If this occurs in the real Earth, then substantial reduction in frictional resistance on the north Hayward fault is expected, which might in turn be expected to influence the distribution of creep. Interaction effects on a shorter time scale are also evident. The 1906 San Francisco, and 1989 Loma Prieta earthquakes are calculated to have reduced stress on the Hayward fault at seismogenic depths. Models of the 1906 earthquake show complex interactions; coseismic static stress changes drop stress on the north Hayward fault while upper mantle viscoelastic relaxation slightly raises the stressing rate. Stress recovery is calculated to have occurred by ~1980, though earthquake probability is still affected by the delay induced by stress reduction. We conclude that the model Hayward fault is strongly influenced by its neighbors, and it is worth considering these effects when studying and attempting to understand the real fault.

  11. Subsurface geometry of the San Andreas-Calaveras fault junction: influence of the Coast Range Ophiolite (United States)

    Watt, J. T.; Ponce, D. A.; Graymer, R. W.; Jachens, R. C.; Simpson, R. W.


    Potential-field modeling, surface geologic mapping, and relocated seismicity are used to investigate the three-dimensional structure of the San Andreas-Calaveras fault junction to gain insight into regional tectonics, fault kinematics, and seismic hazard. South of the San Francisco Bay area, the San Andreas and Hayward-Calaveras fault zones join to become a single San Andreas Fault. The fault junction, as defined in this study, represents a three-dimensional volume of crust extending from San Juan Bautista in the north to Bitterwater Valley in the south, bounded by the San Andreas Fault on the southwest and the Calaveras fault zone on the northeast. South of Hollister, the Calaveras fault zone includes the Paicines, San Benito, and Pine Rock faults. Within the junction, the San Andreas and Calaveras faults are both creeping at the surface, and strike parallel to each other for about 50 km, separated by only 2 to 6 km, but never actually merge at the surface. Geophysical evidence suggests that the San Andreas and Calaveras faults dip away from each other within the northern portion of the fault junction, bounding a triangular wedge of crust. This wedge changes shape to the south as the dips of both the San Andreas and Calaveras faults vary along strike. The main trace of the San Andreas Fault is clearly visible in cross-sections of relocated seismicity as a vertical to steeply southwest-dipping structure between 5 and 10 km depth throughout the junction. The Calaveras fault dips steeply to the northeast in the northern part of the junction. Near the intersection with the Vallecitos syncline, the dip of the Calaveras fault, as identified in relocated seismicity, shallows to 60 degrees. Northeast of the Calaveras fault, we identify a laterally extensive magnetic body 1 to 8 km below the surface that we interpret as a folded 1 to 3 km-thick tabular body of Coast Range Ophiolite at the base of the Vallecitos syncline. Potential-field modeling and relocated seismicity

  12. Migrating tremors illuminate complex deformation beneath the seismogenic San Andreas fault (United States)

    Shelly, D.R.


    The San Andreas fault is one of the most extensively studied faults in the world, yet its physical character and deformation mode beneath the relatively shallow earthquake-generating portion remain largely unconstrained. Tectonic non-volcanic tremor, a recently discovered seismic signal probably generated by shear slip on the deep extension of some major faults, can provide new insight into the deep fate of such faults, including that of the San Andreas fault near Parkfield, California. Here I examine continuous seismic data from mid-2001 to 2008, identifying tremor and decomposing the signal into different families of activity based on the shape and timing of the waveforms at multiple stations. This approach allows differentiation between activities from nearby patches of the deep fault and begins to unveil rich and complex patterns of tremor occurrence. I find that tremor exhibits nearly continuous migration, with the most extensive episodes propagating more than 20 kilometres along fault strike at rates of 15-80 kilometres per hour. This suggests that the San Andreas fault remains a localized through-going structure, at least to the base of the crust, in this area. Tremor rates and recurrence behaviour changed markedly in the wake of the 2004 magnitude-6.0 Parkfield earthquake, but these changes were far from uniform within the tremor zone, probably reflecting heterogeneous fault properties and static and dynamic stresses decaying away from the rupture. The systematic recurrence of tremor demonstrated here suggests the potential to monitor detailed time-varying deformation on this portion of the deep San Andreas fault, deformation which unsteadily loads the shallower zone that last ruptured in the 1857 magnitude-7.9 Fort Tejon earthquake. ?? 2010 Macmillan Publishers Limited. All rights reserved.

  13. Scientific drilling into the San Andreas Fault Zone - an overview of SAFOD's first five years (United States)

    Zoback, Mark; Hickman, Stephen; Ellsworth, William; ,


    The San Andreas Fault Observatory at Depth (SAFOD) was drilled to study the physical and chemical processes controlling faulting and earthquake generation along an active, plate-bounding fault at depth. SAFOD is located near Parkfield, California and penetrates a section of the fault that is moving due to a combination of repeating microearthquakes and fault creep. Geophysical logs define the San Andreas Fault Zone to be relatively broad (~200 m), containing several discrete zones only 2–3 m wide that exhibit very low P- and S-wave velocities and low resistivity. Two of these zones have progressively deformed the cemented casing at measured depths of 3192 m and 3302 m. Cores from both deforming zones contain a pervasively sheared, cohesionless, foliated fault gouge that coincides with casing deformation and explains the observed extremely low seismic velocities and resistivity. These cores are being now extensively tested in laboratories around the world, and their composition, deformation mechanisms, physical properties, and rheological behavior are studied. Downhole measurements show that within 200 m (maximum) of the active fault trace, the direction of maximum horizontal stress remains at a high angle to the San Andreas Fault, consistent with other measurements. The results from the SAFOD Main Hole, together with the stress state determined in the Pilot Hole, are consistent with a strong crust/weak fault model of the San Andreas. Seismic instrumentation has been deployed to study physics of faulting—earthquake nucleation, propagation, and arrest—in order to test how laboratory-derived concepts scale up to earthquakes occurring in nature.

  14. Variability of fault slip behavior along the San Andreas Fault in the San Juan Bautista Region (United States)

    Taira, Taka'aki; Bürgmann, Roland; Nadeau, Robert M.; Dreger, Douglas S.


    An improved understanding of the time history of fault slip at depth is an essential step toward understanding the underlying mechanics of the faulting process. Using a waveform cross-correlation approach, we document spatially and temporally varying fault slip along the northernmost creeping section of the San Andreas Fault near San Juan Bautista (SJB), California, by systematically examining spatiotemporal behaviors of characteristically repeating earthquakes (CREs). The spatial distribution of pre-1998 SJB earthquake (1984-1998) fault slip rate inferred from the CREs reveals a ~15 km long low creep or partially locked section located near the 1998 Mw 5.1 SJB earthquake rupture. A finite-fault slip inversion reveals that the rupture of the 1998 SJB earthquake is characterized by the failure of a compact ~4 km2 asperity with a maximum slip of about 90 cm and corresponding peak stress drop of up to 50 MPa, whereas the mean stress drop is about 15 MPa. Following the 1998 earthquake, the CRE activity was significantly increased in a 5-10 km deep zone extending 2-7 km northwest of the main shock, which indicates triggering of substantial aseismic slip. The postseismic slip inferred from the CRE activity primarily propagated to the northwest and released a maximum slip of 9 cm. In this 5-10 km depth range, the estimated postseismic moment release is 8.6 × 1016 N m, which is equivalent to Mw 5.22. The aseismic slip distribution following the 1998 earthquake is not consistent with coseismic stress-driven afterslip but represents a triggered, long-lasting slow earthquake.

  15. Elevated time-dependent strengthening rates observed in San Andreas Fault drilling samples (United States)

    Ikari, Matt J.; Carpenter, Brett M.; Vogt, Christoph; Kopf, Achim J.


    The central San Andreas Fault in California is known as a creeping fault, however recent studies have shown that it may be accumulating a slip deficit and thus its seismogenic potential should be seriously considered. We conducted laboratory friction experiments measuring time-dependent frictional strengthening (healing) on fault zone and wall rock samples recovered during drilling at the San Andreas Fault Observatory at Depth (SAFOD), located near the southern edge of the creeping section and in the direct vicinity of three repeating microearthquake clusters. We find that for hold times of up to 3000 s, frictional healing follows a log-linear dependence on hold time and that the healing rate is very low for a sample of the actively shearing fault core, consistent with previous results. However, considering longer hold times up to ∼350,000 s, the healing rate accelerates such that the data for all samples are better described by a power law relation. In general, samples having a higher content of phyllosilicate minerals exhibit low log-linear healing rates, and the notably clay-rich fault zone sample also exhibits strong power-law healing when longer hold times are included. Our data suggest that weak faults, such as the creeping section of the San Andreas Fault, can accumulate interseismic shear stress more rapidly than expected from previous friction data. Using the power-law dependence of frictional healing on hold time, calculations of recurrence interval and stress drop based on our data accurately match observations of discrete creep events and repeating Mw = 2 earthquakes on the San Andreas Fault.

  16. San Andreas fault zone, California: M≥5.5 earthquake history (United States)

    Toppozada, Tousson R.; Branum, D.M.; Reichle, M.S.; Hallstrom, C.L.


    The San Andreas fault zone has been a very significant source of major California earthquakes. From 1812 to 1906 it generated four major earthquakes of M 7 or larger in two pairs on two major portions of the fault. A pair of major earthquakes occurred on the central to southern region, where the 1857 faulting overlapped the 1812 earthquake faulting. A pair of major earthquakes occurred on the northern region, where the 1906 faulting overlapped the 1838 earthquake faulting. Also, earthquakes of M 7 occurred in the San Francisco Bay area on the Hayward fault in 1868 and the Santa Cruz Mountains near Loma Prieta in 1989 and on the Imperial fault near the border with Mexico in 1940.

  17. Quaternary crustal deformation along a major branch of the San Andreas fault in central California (United States)

    Weber, G.E.; Lajoie, K.R.; Wehmiller, J. F.


    .8 km wide east of Point Ano Nuevo is downdropped as much as 20 m between two primary traces to form a graben presently filling with Holocene deposits. Where exposed in the sea cliff, these deposits are folded into a vertical attitude adjacent to the fault plane forming the south-west margin of the graben. Near Point Ano Nuevo sedimentary deposits and fault rubble beneath a secondary high-angle reverse fault record three and possibly six distinct offset events in the past 125 ka. The three primary fault traces offset in a right-lateral sense the shoreline angles of the two lowest terraces east of Point Ano Nuevo. The rates of displacement on the three traces are similar. The average rate of horizontal offset across the entire zone is between 0.63 and 1.30 cm/yr, based on an amino-acid age estimate of 125 ka for the first terrace, and a reasonable guess of 200-400 ka for the second terrace. Rates of this magnitude make up a significant part of the deficit between long-term relative plate motions (estimated by others to be about 6 cm/yr) and present displacement rates along other parts of the San Andreas fault system (about 3.2 cm/yr). Northwestward tilt and convergence of six marine terraces northeast of Ano Nuevo (southwest side of the fault zone) indicate continuous gentle warping associated with right-lateral displacement since early or middle Pleistocene time. Minimum local crustal shortening of this block parallel to the fault is 0.2% based on tilt of the highest terrace. Five major, evenly spaced terraces southeast of Ano Nuevo on the southwest flank of Mt. Ben Lomond (northeast side of the fault zone) rise to an elevation of 240 m, indicating relatively constant uplift (about 0.19 m/ka and southwestward tilt since Early or Middle Pleistocene time (Bradley and Griggs, 1976). ?? 1979.

  18. Habitat information in the region on the underwater San Andreas Fault - Topic: Exploring the Undersea San Andreas Fault: Revealing the Past, Present, and Future at the Centennial of the Great 1906 Earthquake (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — During this exploration, the first comprehensive high-resolution multi-beam sonar and seismic reflection survey of the Northern San Andreas Fault (NSAF) was...

  19. Precise tremor source locations and amplitude variations along the lower-crustal central San Andreas Fault (United States)

    Shelly, David R.; Hardebeck, Jeanne L.


    We precisely locate 88 tremor families along the central San Andreas Fault using a 3D velocity model and numerous P and S wave arrival times estimated from seismogram stacks of up to 400 events per tremor family. Maximum tremor amplitudes vary along the fault by at least a factor of 7, with by far the strongest sources along a 25 km section of the fault southeast of Parkfield. We also identify many weaker tremor families, which have largely escaped prior detection. Together, these sources extend 150 km along the fault, beneath creeping, transitional, and locked sections of the upper crustal fault. Depths are mostly between 18 and 28 km, in the lower crust. Epicenters are concentrated within 3 km of the surface trace, implying a nearly vertical fault. A prominent gap in detectible activity is located directly beneath the region of maximum slip in the 2004 magnitude 6.0 Parkfield earthquake.

  20. Low-altitude aerial color digital photographic survey of the San Andreas Fault (United States)

    Lynch, David K.; Hudnut, Kenneth W.; Dearborn, David S.P.


    Ever since 1858, when Gaspard-Félix Tournachon (pen name Félix Nadar) took the first aerial photograph (Professional Aerial Photographers Association 2009), the scientific value and popular appeal of such pictures have been widely recognized. Indeed, Nadar patented the idea of using aerial photographs in mapmaking and surveying. Since then, aerial imagery has flourished, eventually making the leap to space and to wavelengths outside the visible range. Yet until recently, the availability of such surveys has been limited to technical organizations with significant resources. Geolocation required extensive time and equipment, and distribution was costly and slow. While these situations still plague older surveys, modern digital photography and lidar systems acquire well-calibrated and easily shared imagery, although expensive, platform-specific software is sometimes still needed to manage and analyze the data. With current consumer-level electronics (cameras and computers) and broadband internet access, acquisition and distribution of large imaging data sets are now possible for virtually anyone. In this paper we demonstrate a simple, low-cost means of obtaining useful aerial imagery by reporting two new, high-resolution, low-cost, color digital photographic surveys of selected portions of the San Andreas fault in California. All pictures are in standard jpeg format. The first set of imagery covers a 92-km-long section of the fault in Kern and San Luis Obispo counties and includes the entire Carrizo Plain. The second covers the region from Lake of the Woods to Cajon Pass in Kern, Los Angeles, and San Bernardino counties (151 km) and includes Lone Pine Canyon soon after the ground was largely denuded by the Sheep Fire of October 2009. The first survey produced a total of 1,454 oblique digital photographs (4,288 x 2,848 pixels, average 6 Mb each) and the second produced 3,762 nadir images from an elevation of approximately 150 m above ground level (AGL) on the

  1. Paleomagnetic reorientation of San Andreas Fault Observatory at Depth (SAFOD) core (United States)

    Pares, J.M.; Schleicher, A.M.; van der Pluijm, B.A.; Hickman, S.


    We present a protocol for using paleomagnetic analysis to determine the absolute orientation of core recovered from the SAFOD borehole. Our approach is based on determining the direction of the primary remanent magnetization of a spot core recovered from the Great Valley Sequence during SAFOD Phase 2 and comparing its direction to the expected reference field direction for the Late Cretaceous in North America. Both thermal and alternating field demagnetization provide equally resolved magnetization, possibly residing in magnetite, that allow reorientation. Because compositionally similar siltstones and fine-grained sandstones were encountered in the San Andreas Fault Zone during Stage 2 rotary drilling, we expect that paleomagnetic reorientation will yield reliable core orientations for continuous core acquired from directly within and adjacent to the San Andreas Fault during SAFOD Phase 3, which will be key to interpretation of spatial properties of these rocks. Copyright 2008 by the American Geophysical Union.

  2. Hydrogeologic Architecture of the San Andreas Fault near the Logan Quarry (United States)

    Xue, L.; Brodsky, E. E.; Erskine, J.; Fulton, P. M.; Carter, R.


    Hydrogeologic properties of fault zones are critical to the faulting processes; however, they are not well understood and difficult to measure in situ. Recording the tidal response of water level is a useful method to measure the in-situ properties. We utilize an array of wells near the San Andreas Fault zone in the Logan Quarry to study the fault zone hydrogeologic architecture by measuring the water tidal response. The measured specific storage and permeability show that there is a localized zone near the fault with higher specific storage and larger permeability than the surrounding region. This change of properties might be related to the fault zone fracture distribution. Surprisingly, the change of the specific storage is the clearest signal. The inferred compliance contrast is consistent with prior estimates of elastic moduli change in the near-fault environment, but the hydrogeologic effects of the compliance change have never before been measured on a major active fault. The observed specific storage structure implies that the fault zone plays an important role in permeability enhancement by seismic shaking. In addition, the measured diffusivity is about 10-2 m2/s, which is comparable to the post-earthquake hydraulic diffusivity measured on the Wenchuan Earthquake Fault. This observed high diffusivity with little variability inside the fault zone might suggest the accumulated pore pressure during interseismic period distributes over a broad region.

  3. San Andreas fault geometry at Desert Hot Springs, California, and its effects on earthquake hazards and groundwater (United States)

    Catchings, R.D.; Rymer, M.J.; Goldman, M.R.; Gandhok, G.


    The Mission Creek and Banning faults are two of the principal strands of the San Andreas fault zone in the northern Coachella Valley of southern California. Structural characteristics of the faults affect both regional earthquake hazards and local groundwater resources. We use seismic, gravity, and geological data to characterize the San Andreas fault zone in the vicinity of Desert Hot Springs. Seismic images of the upper 500 m of the Mission Creek fault at Desert Hot Springs show multiple fault strands distributed over a 500 m wide zone, with concentrated faulting within a central 200 m wide area of the fault zone. High-velocity (up to 5000 m=sec) rocks on the northeast side of the fault are juxtaposed against a low-velocity (6.0) earthquakes in the area (in 1948 and 1986) occurred at or near the depths (~10 to 12 km) of the merged (San Andreas) fault. Large-magnitude earthquakes that nucleate at or below the merged fault will likely generate strong shaking from guided waves along both fault zones and from amplified seismic waves in the low-velocity basin between the two fault zones. The Mission Creek fault zone is a groundwater barrier with the top of the water table varying by 60 m in depth and the aquifer varying by about 50 m in thickness across a 200 m wide zone of concentrated faulting.

  4. LiDAR-derived measurements of slip in the most recent ground-rupturing earthquakes along elements of the San Andreas fault system (United States)

    Haddad, D. E.; Madden, C.; Salisbury, J. B.; Arrowsmith, R.; Weldon, R. J.


    Tectonically displaced geomorphic markers record the surface manifestation of earthquake-induced ground ruptures. Of particular interest to earthquake forecast models is the slip produced during the most recent ground-rupturing earthquake. High-resolution digital topography from light detection and ranging (LiDAR) is a powerful tool for measuring the most recent meter-scale slip along fault zones. We present surface slip measurements of recent ground-rupturing earthquakes along the Garlock, Owens Valley, Elsinore, and Blackwater-Calico fault zones. Fault scarp traces were mapped using LiDAR-derived digital elevation models (DEMs), local topographic gradient and relief maps, and aerial photography. An individual slip measurement was made for each offset feature by iteratively reconstructing the topography on either side of the fault and finding the best-matching vertically backslipped value. A goodness-of-fit approach was then used to calculate the best laterally backslipped displacement using a combination of vertical backslip, horizontal backslip, and topographic scaling. Along-strike, reach-averaged surface displacement distributions of the most recent earthquakes were then generated from the LiDAR-derived offsets and compared to published field-derived offset measurements. For the eastern section of the Garlock fault, our LiDAR-derived offsets compared well with those measured in the field and attained an R2 value of 0.88 with reach-averaged slip in the last event of 4.19 m ±0.69 m for the Searles Valley area (2.67 km reach), 4.65 m +0.76/-0.92 m for the Pilot Knob Valley area (24.68 km reach), and 3.45 m +0.82/-0.87 m for the Leach Lake and Avawatz Mountains areas (12.65 km reach), computed from a total of 129 offsets. Our results show that LiDAR-derived offset measurements compare well with field measurements in the comprehensive documentation of along-strike surface slip distributions of the most recent earthquake. Furthermore, our results demonstrate the

  5. Connecting Aseismic Slip and Microseismicity on the Central San Andreas Fault (United States)

    Johanson, I. A.; Bürgmann, R.


    High precision micro-earthquake relocations have revealed seismicity structures that may be an indicator of the fault's slip characteristics. Characteristically repeating micro-earthquakes and aligned streaks of micro-seismicity suggest that these structures are associated with areas of active aseismic fault slip. A general inverse correspondence between zones of abundant micro-seismicity and the coseismic slip area of large earthquakes also implies a relationship between creep and micro-earthquakes. We test this relationship using geodetic measurements of near-fault deformation. Modeling of such measurements allow for determination of locked and creeping sections of the fault. We focus on the central San Andreas fault near San Juan Bautista; a segment which experiences both aseismic and seismic fault slip and where there is a long history of geodetic measurements. Aseismic slip on the central San Andreas is time dependent and has varied in response to regional earthquakes and in the form of slow earthquakes. Dislocations in an elastic half space are used to evaluate a range of scenario fault slip models whose geometry is guided by the locations of micro-seismic streaks. The inversions for distributed sub-surface slip are constrained by range-change data from InSAR and GPS site velocities. The InSAR data (ERS1&2 track 299 frame 2861) spans from 1996-2000 and were processed using ROI_Pac with the SNAPHU unwrapper and combined in a patchwork stack to reduce atmospheric errors. Campaign and continuous GPS data were processed using GAMIT/GLOBK and form part of the regional BA¯VU¯ dataset. To minimize the effect on our analysis of transient slip induced by the 1989 Loma Prieta earthquake, we limit our dataset to GPS observations from 1994 to 2003. Preliminary results confirm that the presence of seismicity streaks and characteristically repeating micro-earthquakes are indicative of aseismic slip. However, the absence of such seismicity patterns does not necessarily

  6. Geodetic measurement of deformation east of the San Andreas fault in central California (United States)

    Sauber, Jeanne; Lisowski, Michael; Solomon, Sean C.

    Triangulation and trilateration data from two geodetic networks located between the San Andreas fault and the Great Valley have been used to calculate shear strain rates in the Diablo Range and to estimate the slip rate along the Calaveras and Paicines faults in central California. The shear strain rates, γ1 and γ2, were estimated independently from angle changes using Prescott's method and from the simultaneous reduction for station position and strain parameters using the DYNAP method with corrections to reduce the triangulation and trilateration data to a common reference surface. On the basis of Prescott's method, the average shear strain rate across the Diablo Range for the time period between 1962 and 1982 is 0.15±0.08 μrad/yr, with the orientation of the most compressive strain (β) at N16°E±14°. Utilizing corrections for the deflection of the vertical and the geoid reference ellipsoid separation computed on the basis of local gravity observations, γ = 0.19±0.09 μrad/yr and β = N16°E±13°. Although γ is not significantly greater than zero, at the 95% confidence level the orientation of β is similar to the direction of maximum compressive strain indicated by the orientation of major fold structures in the region (N25°E). We infer that the measured strain is due to compression across the folds of this area; the average shear straining corresponds to a relative shortening rate of 5.7±2.7 mm/yr. In contrast to the situation throughout most of the Coast Ranges where fold axes have orientations approximately parallel to the San Andreas fault, within the Diablo Range between Hollister and Coalinga the trends of the fold axes are different and are thought to be controlled by reactivation of older structures. From trilateration measurements made between 1972 and 1987 on lines that are within 10 km of the San Andreas fault, a slip rate of 10-12 mm/yr was calculated for the Calaveras-Paicines fault south of Hollister. The slip rate on the Paicines

  7. Identification of Necessary Conditions for Super-shear Wave Rupture Speeds: The San Andreas Fault (United States)

    Das, S.


    The 2001 Kunlun, Tibet earthquake taught us that the portion of a strike-slip fault most likely to propagate at super-shear speeds are the long straight portions. This is only a necessary (but not sufficient) condition. That is, once a fault accelerates to the maximum permissible speed, it can continue at this speed provided it is straight and there are no obstacles along the way, and provided the fault friction is low. For the Tibet earthquake, the 100 km region of highest rupture speed also had the highest slip rate, the highest slip and the highest stress drop (Robinson et al., JGR, 2006). Off-fault cracks due to the passage of the Mach cone exists in only that portion of the fault identified as travelling at super-shear speed and not in other places along the fault (Bhat et al., JGR, 2007). Re-examination of earlier reports of super-shear rupture speeds on the North Anatolian fault and the Denali fault show that such speeds did occur on the straight section of these faults. Of course all straight portions of faults will not reach super-shear speeds. So what can the Tibet earthquake teach us about the San Andreas fault? Both the 1906 and the 1857 have long, straight portions, the former having been identified by Song et al. (EOS, 2005) as having reached super-shear speeds to the north of San Francisco, the region of highest slip. If the repeat of the 1857 starts in the central valley, as it is believed to have done in 1857, it has the potential to propagate at super-shear speeds through the long, straight portion of the San Andread fault in the Carrizo Plain, the region believed to have had the largest displacement in 1857 based on paleoseismic studies. The resulting shock waves would strike the highly populated regions of Santa Barbara and the Los Angeles Basin (Das, Science, 2007).

  8. Tidal triggering of earthquakes suggests poroelastic behavior on the San Andreas Fault (United States)

    Delorey, Andrew A.; van der Elst, Nicholas J.; Johnson, Paul A.


    Tidal triggering of earthquakes is hypothesized to provide quantitative information regarding the fault's stress state, poroelastic properties, and may be significant for our understanding of seismic hazard. To date, studies of regional or global earthquake catalogs have had only modest successes in identifying tidal triggering. We posit that the smallest events that may provide additional evidence of triggering go unidentified and thus we developed a technique to improve the identification of very small magnitude events. We identify events applying a method known as inter-station seismic coherence where we prioritize detection and discrimination over characterization. Here we show tidal triggering of earthquakes on the San Andreas Fault. We find the complex interaction of semi-diurnal and fortnightly tidal periods exposes both stress threshold and critical state behavior. Our findings reveal earthquake nucleation processes and pore pressure conditions - properties of faults that are difficult to measure, yet extremely important for characterizing earthquake physics and seismic hazards.

  9. Holocene geologic slip rate for the Banning strand of the southern San Andreas Fault, southern California (United States)

    Gold, Peter O.; Behr, Whitney M.; Rood, Dylan; Sharp, Warren D.; Rockwell, Thomas; Kendrick, Katherine J.; Salin, Aaron


    Northwest directed slip from the southern San Andreas Fault is transferred to the Mission Creek, Banning, and Garnet Hill fault strands in the northwestern Coachella Valley. How slip is partitioned between these three faults is critical to southern California seismic hazard estimates but is poorly understood. In this paper, we report the first slip rate measured for the Banning fault strand. We constrain the depositional age of an alluvial fan offset 25 ± 5 m from its source by the Banning strand to between 5.1 ± 0.4 ka (95% confidence interval (CI)) and 6.4 + 3.7/−2.1 ka (95% CI) using U-series dating of pedogenic carbonate clast coatings and 10Be cosmogenic nuclide exposure dating of surface clasts. We calculate a Holocene geologic slip rate for the Banning strand of 3.9 + 2.3/−1.6 mm/yr (median, 95% CI) to 4.9 + 1.0/−0.9 mm/yr (median, 95% CI). This rate represents only 25–35% of the total slip accommodated by this section of the southern San Andreas Fault, suggesting a model in which slip is less concentrated on the Banning strand than previously thought. In rejecting the possibility that the Banning strand is the dominant structure, our results highlight an even greater need for slip rate and paleoseismic measurements along faults in the northwestern Coachella Valley in order to test the validity of current earthquake hazard models. In addition, our comparison of ages measured with U-series and 10Be exposure dating demonstrates the importance of using multiple geochronometers when estimating the depositional age of alluvial landforms.

  10. Deep rock damage in the San Andreas Fault revealed by P- and S-type fault-zone-guided waves (United States)

    Ellsworth, William L.; Malin, Peter E.


    Damage to fault-zone rocks during fault slip results in the formation of a channel of low seismic-wave velocities. Within such channels guided seismic waves, denoted by Fg, can propagate. Here we show with core samples, well logs and Fg-waves that such a channel is crossed by the SAFOD (San Andreas Fault Observatory at Depth) borehole at a depth of 2.7 km near Parkfield, California, USA. This laterally extensive channel extends downwards to at least half way through the seismogenic crust, more than about 7 km. The channel supports not only the previously recognized Love-type- (FL) and Rayleigh-type- (FR) guided waves, but also a new fault-guided wave, which we name FF. As recorded 2.7 km underground, FF is normally dispersed, ends in an Airy phase, and arrives between the P- and S-waves. Modelling shows that FF travels as a leaky mode within the core of the fault zone. Combined with the drill core samples, well logs and the two other types of guided waves, FF at SAFOD reveals a zone of profound, deep, rock damage. Originating from damage accumulated over the recent history of fault movement, we suggest it is maintained either by fracturing near the slip surface of earthquakes, such as the 1857 Fort Tejon M 7.9, or is an unexplained part of the fault-creep process known to be active at this site.

  11. Investigating the creeping section of the San Andreas Fault using ALOS PALSAR interferometry (United States)

    Agram, P. S.; Wortham, C.; Zebker, H. A.


    In recent years, time-series InSAR techniques have been used to study the temporal characteristics of various geophysical phenomena that produce surface deformation including earthquakes and magma migration in volcanoes. Conventional InSAR and time-series InSAR techniques have also been successfully used to study aseismic creep across faults in urban areas like the Northern Hayward Fault in California [1-3]. However, application of these methods to studying the time-dependent creep across the Central San Andreas Fault using C-band ERS and Envisat radar satellites has resulted in limited success. While these techniques estimate the average long-term far-field deformation rates reliably, creep measurement close to the fault (Exploration Agency (JAXA) in 2006, to study the temporal characteristics of creep across the Central San Andreas Fault. The longer wavelength at L-band improves observed correlation over the entire scene which significantly increased the ground area coverage of estimated deformation in each interferogram but at the cost of decreased sensitivity of interferometric phase to surface deformation. However, noise levels in our deformation estimates can be decreased by combining information from multiple SAR acquisitions using time-series InSAR techniques. We analyze 13 SAR acquisitions spanning the time-period from March 2007 to Dec 2009 using the Short Baseline Subset Analysis (SBAS) time-series InSAR technique [3]. We present detailed comparisons of estimated time-series of fault creep as a function of position along the fault including the locked section around Parkfield, CA. We also present comparisons between the InSAR time-series and GPS network observations in the Parkfield region. During these three years of observation, the average fault creep is estimated to be 35 mm/yr. References [1] Bürgmann,R., E. Fielding and, J. Sukhatme, Slip along the Hayward fault, California, estimated from space-based synthetic aperture radar interferometry

  12. A Bayesian exploration of the distribution of aseismic slip along the creeping section of the San Andreas Fault, California (United States)

    Jolivet, R.; Agram, P. S.; Simons, M.; Shen, Z.; Zhang, H.


    section. We discretize both fault planes into rectangular patches with sizes varying as a function of depth and compute the static displacement Green's functions in a continuous half space using Okada's solution and in a layered space. We use a massively parallel implementation of CATMIP, a bayesian solver optimized for GPUs, to determine the full posterior probability of each parameter, including slip rates on the shallow section of the SAF and CPF and slip rates on deep dislocations to account for the interseimic tectonic loading across the San Andreas fault system. Our results confirm the variable distribution of creep rates along strike and at depth. Maximum slip rate is inferred north of Parkfield, while it decays toward the north. We also highlight a close correlation between the location of micro- and moderate seismicity and patches of high slip rate.

  13. Fault Creep along the Southern San Andreas from Interferometric Synthetic Aperture Radar, Permanent Scatterers, and Stacking (United States)

    Lyons, Suzanne; Sandwell, David


    Interferometric synthetic aperture radar (InSAR) provides a practical means of mapping creep along major strike-slip faults. The small amplitude of the creep signal (less than 10 mm/yr), combined with its short wavelength, makes it difficult to extract from long time span interferograms, especially in agricultural or heavily vegetated areas. We utilize two approaches to extract the fault creep signal from 37 ERS SAR images along the southem San Andreas Fault. First, amplitude stacking is utilized to identify permanent scatterers, which are then used to weight the interferogram prior to spatial filtering. This weighting improves correlation and also provides a mask for poorly correlated areas. Second, the unwrapped phase is stacked to reduce tropospheric and other short-wavelength noise. This combined processing enables us to recover the near-field (approximately 200 m) slip signal across the fault due to shallow creep. Displacement maps fiom 60 interferograms reveal a diffuse secular strain buildup, punctuated by localized interseismic creep of 4-6 mm/yr line of sight (LOS, 12-18 mm/yr horizontal). With the exception of Durmid Hill, this entire segment of the southern San Andreas experienced right-lateral triggered slip of up to 10 cm during the 3.5-year period spanning the 1992 Landers earthquake. The deformation change following the 1999 Hector Mine earthquake was much smaller (4 cm) and broader than for the Landers event. Profiles across the fault during the interseismic phase show peak-to-trough amplitude ranging from 15 to 25 mm/yr (horizontal component) and the minimum misfit models show a range of creeping/locking depth values that fit the data.

  14. San Andreas Fault, California, M 5.5 or greater Earthquakes 1800-2000 (United States)

    Toppozada, T.; Branum, D.; Reichle, M.; Hallstrom, C.


    The San Andreas fault has been the most significant source of major California earthquakes since 1800. From 1812 to 1906 it generated four major earthquakes of M 7.2 or greater in two pairs on two major regions of the fault. A pair of major earthquakes occurred on the Central to Southern region, where the 1857 faulting overlapped the 1812 earthquake faulting. And a pair of major earthquakes occurred on the Northern region, where the 1906 faulting overlapped the 1838 earthquake faulting. The 1812 earthquake resulted from a rupture of up to about 200 km, from the region of Cajon Pass to as far as about 50 km west of Fort Tejon (Sieh and others, 1989). This rupture is the probable source of both the destructive 1812.12.8 "San Juan Capistrano" and the 1812.12.21 "Santa Barbara Channel" earthquakes. The 1838 earthquake's damage effects throughout the Bay area, from San Francisco to Santa Clara Valley and Monterey, were unequalled by any Bay area earthquake other than the 1906 event. The mainshock's effects, and numerous strong probable aftershocks in the San Juan Bautista vicinity in the following three years, suggest 1838 faulting from San Francisco to San Juan Bautista, and M about 7.4. The 630 km length of the San Andreas fault between San Francisco and Cajon Pass ruptured in the 1838 and 1857 earthquakes, except for about 75 km between Bitterwater and San Juan Bautista. The 1840-1841 probable aftershocks of the 1838 event occurred near San Juan Bautista, and the foreshocks and aftershocks of the 1857 event occurred near Bitterwater. In the Bitterwater area, strong earthquakes continued to occur until the 1885 earthquake of M 6.5. Near Parkfield, 40 to 70 km southeast of Bitterwater, M 5.5 or greater earthquakes have occurred from the 1870s to the 1960s. In the total Bitterwater to Parkfield zone bracketing the northern end of the 1857 rupture, the seismicity and moment release has decreased steadily since 1857, and has tended to migrate southeastward with time. The

  15. Scientific Drilling Into the San Andreas Fault Zone —An Overview of SAFOD’s First Five Years

    Directory of Open Access Journals (Sweden)

    Stephen Hickman


    Full Text Available The San Andreas Fault Observatory at Depth (SAFODwas drilled to study the physical and chemical processes controlling faulting and earthquake generation along an active, plate-bounding fault at depth. SAFOD is located near Parkfield, California and penetrates a section of the fault that is moving due to a combination of repeating microearthquakes and fault creep. Geophysical logs define the SanAndreas Fault Zone to be relatively broad (~200 m, containing several discrete zones only 2–3 m wide that exhibit very low P- and S-wave velocities and low resistivity. Two of these zones have progressively deformed the cemented casing at measured depths of 3192 m and 3302 m. Cores from both deforming zones contain a pervasively sheared, cohesionless, foliated fault gouge that coincides with casing deformation and explains the observed extremely low seismic velocities and resistivity. These cores are being now extensivelytested in laboratories around the world, and their composition, deformation mechanisms, physical properties, and rheological behavior are studied. Downhole measurements show that within 200 m (maximum of the active fault trace, the direction of maximum horizontal stress remains at a high angle to the San Andreas Fault, consistent with other measurements. The results from the SAFOD Main Hole, together with the stress state determined in the Pilot Hole, are consistent with a strong crust/weak fault model of the San Andreas. Seismic instrumentation has been deployed to study physics of faulting—earthquake nucleation, propagation, and arrest—in order to test how laboratory-derived concepts scale up to earthquakes occurring in nature.

  16. Constraining deformation at the lithosphere-asthenosphere boundary beneath the San Andreas fault with Sp phases (United States)

    Fischer, K. M.; Ford, H. A.; Lekic, V.


    The geometry of deformation in the deep mantle lithosphere beneath strike-slip plate boundaries has been enigmatic, with models ranging from localized shear zones that are deep extensions of individual crustal faults to broad zones of diffuse, distributed shear with widths of hundreds of kilometers. Using seismic phases that convert from shear to compressional motion (Sp) at the base of the lithosphere beneath California, we find evidence for strike-slip deformation in the deepest mantle lithosphere beneath the central San Andreas fault that occurs over a horizontal width of 50 km or less. This study is based on over 135,000 Sp receiver functions from 730 seismic stations, including the Northern and Southern California Seismic Networks and the NSF EarthScope Transportable and Flexible Arrays. Individual Sp receiver functions were calculated using an extended-time multi-taper method and were migrated and stacked according to their three-dimensional conversion point locations using a model for crust (Lowry and Pérez-Gussinyé, 2011) and mantle (Obrebski et al., 2010 and 2011) velocity structure beneath each station and a spline-function representation of the Sp Fresnel zone. Sp conversion points at lithosphere-asthenosphere boundary depths are very dense on both sides of the San Andreas fault, and we interpreted the Sp common conversion point stack only at those nodes with information from more than 300 receiver functions. To the east of the plate boundary, a strong coherent Sp phase, indicative of a decrease in shear-wave velocity with depth, is present in the depth range where tomographic studies image the transition from high velocity lithosphere to low velocity asthenosphere. This phase, interpreted as the seismological lithosphere-asthenosphere boundary, has systematically lower amplitudes on the western side of the plate boundary, indicating that the drop in shear velocity from lithosphere to asthenosphere is either smaller or is distributed over a larger

  17. Investigating the Creeping Segment of the San Andreas fault using Persistent Scatterer Interferometry (United States)

    Agram, P.; Ryder, I.; Rolandone, F.; Zebker, H.


    We analyze the temporal characteristics of the creeping section of the San Andreas fault in Central California, using persistent scatterer interferometry (PS-InSAR) time series methods. In PS-InSAR, we identify a network of pixels whose scattering properties vary little between multiple SAR acquisitions spanning a period of time and use phase measurements at these points as a function of time to derive deformations. Applying PS-InSAR to natural terrains where conventional interferograms tend to suffer decorrelation is difficult, yet several PS-InSAR methods have been proposed and have been shown to work reliably in urban environments. The Stanford Method for PS (StaMPS) was the first method developed to extend the scope of PS-InSAR to work effectively in vegetated regions. We applied a maximum likelihood approach to PS selection and find it to be effective in identifying PS points in vegetated areas of the San Francisco Bay Area and Imperial Valley in California, USA. A key advantage of both StaMPS and the maximum likelihood method are that they do not require an a priori temporal model for the deformation pattern. Here we present results from applying these methods to the creeping section of the San Andreas fault. This segment of the fault creeps at rates in excess of 20 mm per year. Geodetic measurements in this area from creepmeters, alignment arrays and GPS typically have poor spatial and/or temporal resolution. Conventional stacking of ERS interferograms covering this segment of the fault provides good surface deformation information in parts of this region, but is not viable in areas that are heavily decorrelated due to vegetation and topography. The PS methods generate time series of surface displacement, even in steep, vegetated areas, and readily reproduce the creep rate of about 26 mm/yr along the fault and the spatial distribution of deformation away from the fault. The results are consistent, but more detailed than, the observations from GPS networks

  18. Southern San Andreas Fault seismicity is consistent with the Gutenberg-Richter magnitude-frequency distribution (United States)

    Page, Morgan T.; Felzer, Karen


    The magnitudes of any collection of earthquakes nucleating in a region are generally observed to follow the Gutenberg-Richter (G-R) distribution. On some major faults, however, paleoseismic rates are higher than a G-R extrapolation from the modern rate of small earthquakes would predict. This, along with other observations, led to formulation of the characteristic earthquake hypothesis, which holds that the rate of small to moderate earthquakes is permanently low on large faults relative to the large-earthquake rate (Wesnousky et al., 1983; Schwartz and Coppersmith, 1984). We examine the rate difference between recent small to moderate earthquakes on the southern San Andreas fault (SSAF) and the paleoseismic record, hypothesizing that the discrepancy can be explained as a rate change in time rather than a deviation from G-R statistics. We find that with reasonable assumptions, the rate changes necessary to bring the small and large earthquake rates into alignment agree with the size of rate changes seen in epidemic-type aftershock sequence (ETAS) modeling, where aftershock triggering of large earthquakes drives strong fluctuations in the seismicity rates for earthquakes of all magnitudes. The necessary rate changes are also comparable to rate changes observed for other faults worldwide. These results are consistent with paleoseismic observations of temporally clustered bursts of large earthquakes on the SSAF and the absence of M greater than or equal to 7 earthquakes on the SSAF since 1857.

  19. Stress fields of the San Andreas and Queen Charlotte transform faults (United States)

    Kilty, Kevin T.


    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.

  20. Geometrical impact of the San Andreas Fault on stress and seismicity in California (United States)

    Li, Qingsong; Liu, Mian


    Most large earthquakes in northern and central California clustered along the main trace of the San Andreas Fault (SAF), the North American-Pacific plate boundary. However, in southern California earthquakes were rather scattered. Here we suggest that such along-strike variation of seismicity may largely reflect the geometrical impact of the SAF. Using a dynamic finite element model that includes the first-order geometric features of the SAF, we show that strain partitioning and crustal deformation in California are closely related to the geometry of the SAF. In particular, the Big Bend is shown to reduce slip rate on southern SAF and cause high shear stress and strain energy over a broad region in southern California, and a belt of high strain energy in the Eastern California Shear Zone.

  1. Detecting Significant Stress Drop Variations in Large Micro-Earthquake Datasets: A Comparison Between a Convergent Step-Over in the San Andreas Fault and the Ventura Thrust Fault System, Southern California (United States)

    Goebel, T. H. W.; Hauksson, E.; Plesch, A.; Shaw, J. H.


    A key parameter in engineering seismology and earthquake physics is seismic stress drop, which describes the relative amount of high-frequency energy radiation at the source. To identify regions with potentially significant stress drop variations, we perform a comparative analysis of source parameters in the greater San Gorgonio Pass (SGP) and Ventura basin (VB) in southern California. The identification of physical stress drop variations is complicated by large data scatter as a result of attenuation, limited recording bandwidth and imprecise modeling assumptions. In light of the inherently high uncertainties in single stress drop measurements, we follow the strategy of stacking large numbers of source spectra thereby enhancing the resolution of our method. We analyze more than 6000 high-quality waveforms between 2000 and 2014, and compute seismic moments, corner frequencies and stress drops. Significant variations in stress drop estimates exist within the SGP area. Moreover, the SGP also exhibits systematically higher stress drops than VB and shows more scatter. We demonstrate that the higher scatter in SGP is not a generic artifact of our method but an expression of differences in underlying source processes. Our results suggest that higher differential stresses, which can be deduced from larger focal depth and more thrust faulting, may only be of secondary importance for stress drop variations. Instead, the general degree of stress field heterogeneity and strain localization may influence stress drops more strongly, so that more localized faulting and homogeneous stress fields favor lower stress drops. In addition, higher loading rates, for example, across the VB potentially result in stress drop reduction whereas slow loading rates on local fault segments within the SGP region result in anomalously high stress drop estimates. Our results show that crustal and fault properties systematically influence earthquake stress drops of small and large events and should

  2. Examining the Evolution of the Peninsula Segment of the San Andreas Fault, Northern California, Using a 4-D Geologic Model (United States)

    Horsman, E.; Graymer, R. W.; McLaughlin, R. J.; Jachens, R. C.; Scheirer, D. S.


    Retrodeformation of a three-dimensional geologic model allows us to explore the tectonic evolution of the Peninsula segment of the San Andreas Fault and adjacent rock bodies in the San Francisco Bay area. By using geological constraints to quantitatively retrodeform specific surfaces (e.g. unfolding paleohorizontal horizons, removing fault slip), we evaluate the geometric evolution of rock bodies and faults in the study volume and effectively create a four-dimensional model of the geology. The three-dimensional map is divided into fault-bounded blocks and subdivided into lithologic units. Surface geologic mapping provides the foundation for the model. Structural analysis and well data allow extrapolation to a few kilometers depth. Geometries of active faults are inferred from double-difference relocated earthquake hypocenters. Gravity and magnetic data provide constraints on the geometries of low density Cenozoic deposits on denser basement, highly magnetic marker units, and adjacent faults. Existing seismic refraction profiles constrain the geometries of rock bodies with different seismic velocities. Together these datasets and others allow us to construct a model of first-order geologic features in the upper ~15 km of the crust. Major features in the model include the active San Andreas Fault surface; the Pilarcitos Fault, an abandoned strand of the San Andreas; an active NE-vergent fold and thrust belt located E of the San Andreas Fault; regional relief on the basement surface; and several Cenozoic syntectonic basins. Retrodeformation of these features requires constraints from all available datasets (structure, geochronology, paleontology, etc.). Construction of the three-dimensional model and retrodeformation scenarios are non-unique, but significant insights follow from restricting the range of possible geologic histories. For example, we use the model to investigate how the crust responded to migration of the principal slip surface from the Pilarcitos Fault

  3. Aseismic slip on the San Andreas Fault south of Loma Prieta (United States)

    Behr, J.; Bilham, R.; Bodin, P.; Burfoid, R. O.; Bürgmann, R.

    Two digital creepmeters installed within the San Andreas fault zone after the 18 Oct 1989 Loma Prieta main shock show less than 1 cm of post seismic right-lateral slip in the four months following the earthquake. At Mt. Madonna road a 23 mm coseismic fracture slipped a further 3 mm after heavy rain, and at Nyland Ranch near San Juan Bautista the fault slipped approximately 9 mm starting 42 days after the main shock. If the current trend at Nyland Ranch persists, more than 2 cm of post seismic slip will develop by 1991. At both sites minor left-lateral displacements occurred which are attributed to near-surface soil effects. The abutments of the railroad bridge across the Pajaro River at Chittenden, which were extended by the 1906 earthquake, were not extended during the Loma Prieta event although they have evidently moved apart by more than 7 cm since bridge reconstruction in 1940. This corresponds to 10 cm of right-lateral slip which could be related to M>5 events in mid-century or could be due to aseismic slip at a mean rate of 2.1 mm/a. The absence of significant surface slip within the fault zone in the decades before and the months following the Loma Prieta event suggests either that near-surface deformation is distributed over a wide zone or that a slip deficit remains. Several authors have proposed this region as a future location for M≈5 events.

  4. Mechanical Modeling of Near-Fault Deformation Within the Dragon's Back Pressure Ridge, San Andreas Fault, Carrizo Plain, California (United States)

    Hilley, G. E.; Arrowsmith, R.


    This contribution uses field observations and numerical modeling to understand how slip along the variably oriented fault surfaces in the upper few km of the San Andreas Fault (SAF) zone produces near-fault deformation observed within a 4.5-km-long Dragon's Back Pressure Ridge (DBPR) in the Carrizo Plain, central California. Geologic and geomorphic mapping of this feature indicates that the amplitude of monoclinal warping of Quaternary sediments increases from southeast to northwest along the southwestern third of the DBPR, and remains approximately constant throughout the remaining two thirds of the landform. When viewed with other structural observations and limited near-surface magnetotelluric imaging, these geologic observations are most compatible with a scenario in which shallow offset of the SAF to the northeast creates a structural knuckle that is anchored to the North American plate. Thus, deformation accrues as right-lateral strike-slip motion along the SAF moves this obstruction along the fault plane through the DBPR block. We have used the Gale numerical model to simulate deformation expected for geometries similar to those inferred within the vicinity of the DBPR. This is accomplished by relating stresses and strains in the upper crust according to a Drucker-Prager (plastic yielding) constitutive rule. Deformation in the model is driven by applying 35 mm/yr of right-lateral strike-slip motion to the model boundary; this displacement rate is likewise applied to the base of the model. The model geometry of the SAF at the beginning of the loading was fashioned to produce the discontinuity in the geometry of the fault plane that is inferred from field observations. The friction and cohesion of crust on each side of the fault were changed between models to determine the parameter values that preserve the structural discontinuity along the SAF as finite deformation accrued. The structural discontinuity over the ~4.5 km of model displacement is maintained in

  5. Cradle of the Earthquake: Exploring the Underwater San Andreas Fault on the R/V Pacific Storm and the SRV Derek M. Baylis between 20100910 and 20101003 (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Over one hundred years after the devastating Great 1906 Earthquake that nearly destroyed San Francisco, this expedition explored the Northern San Andreas Fault, the...

  6. Correlation of clayey gouge in a surface exposure of the San Andreas fault with gouge at depth from SAFOD: Implications for the role of serpentinite in fault mechanics (United States)

    Moore, Diane E.; Rymer, Michael J.


    Magnesium-rich clayey gouge similar to that comprising the two actively creeping strands of the San Andreas Fault in drill core from the San Andreas Fault Observatory at Depth (SAFOD) has been identified in a nearby outcrop of serpentinite within the fault zone at Nelson Creek. Each occurrence of the gouge consists of porphyroclasts of serpentinite and sedimentary rocks dispersed in a fine-grained, foliated matrix of Mg-rich smectitic clays. The clay minerals in all three gouges are interpreted to be the product of fluid-assisted, shear-enhanced reactions between quartzofeldspathic wall rocks and serpentinite that was tectonically entrained in the fault from a source in the Coast Range Ophiolite. We infer that the gouge at Nelson Creek connects to one or both of the gouge zones in the SAFOD core, and that similar gouge may occur at depths in between. The special significance of the outcrop is that it preserves the early stages of mineral reactions that are greatly advanced at depth, and it confirms the involvement of serpentinite and the Mg-rich phyllosilicate minerals that replace it in promoting creep along the central San Andreas Fault.

  7. A Study of Current Interseismic Deformation of San Andreas Fault, San Bernardino Mountain section, using Interferometric Synthetic Aperture Radar (United States)

    Nee, P.; Funning, G. J.


    The San Andreas fault (SAF) system accommodates a significant fraction of the relative movement between the Pacific and North American plates. In the past 250 years, no significant earthquake was recorded on the southernmost section of the SAF, and thus there exists a substantial ongoing earthquake hazard. Estimates of its slip deficit rate, made with various geologic and geodetic observations typically fall in the range 15-25 mm/yr, in the vicinity of the San Bernadino Mountains. Assuming the fault system slips at a constant rate of 20mm/yr, a slip deficit of 5 m would have accumulated since the last event, equivalent to a potential Mw 7.5 or larger earthquake. To understand how much strain is accumulating on the southern SAF system during the current interseismic period, we investigate the surface deformation using radar interferometry. We use the entire catalog of ERS and Envisat Synthetic Aperture Radar (SAR) data from a descending track well oriented for the SAF (track 399). 53 images from ERS spanning 1992 to late 2000, and 50 images from Envisat spanning 2003 to 2010 are used. We perform ratemap inversion (Biggs et al. 2007, GJI) to obtain an estimate of interseismic slip deficit rate, and Persistent Scatterer InSAR (PSI) analysis to investigate the tectonic and non-tectonic surface displacements across the region. The ratemap inversion algorithm involves simultaneous estimation of long wavelength orbital errors, construction of a ratemap by finding the best fitting rate of each pixel, and estimation of slip deficit rate using a half-space elastic dislocation model (Okada 1985, BSSA) calculated from a representative fault model. We constructed and tested different conceptual models based on the SCEC rectangular community fault model (CFM-R). We find that our ERS data are strongly affected by the postseismic deformation of the 1992 Mw 7.3 Landers Earthquake. We therefore estimate the slip rate using the Envisat dataset, which is much less affected by the

  8. On Offset Stream Measurements and Recent Coseismic Surface Rupture in the Carrizo Section of the San Andreas Fault (United States)

    Brooks, B. A.; Hudnut, K. W.; Akciz, S. O.; Delano, J.; Glennie, C. L.; Prentice, C. S.; DeLong, S.


    Recent studies using airborne laser swath mapping (ALSM) topographic data have provoked debate about whether the Mw 7.9 Fort Tejon 1857 earthquake produced ~5m or ~10m of surface strike-slip displacement in the Carrizo section of the south-central San Andreas fault. Resolution of this discrepancy is important not only for understanding the proposed role of the Carrizo section in controlling repeated south-central San Andreas rupture but also for understanding the general utility of stream offset measurements for earthquake process studies. To explore if higher-resolution topographic data of the offset features would help reconcile the different interpretations, we used a mobile laser scanning (MLS) backpack-mounted system to survey 11 ~5m offset streams given 'high' quality rankings by previous studies. In our surveys, point density was on the order of 1000s pts/m^2 in comparison to 1-4 pts/m^2 for the ALSM data, enabling us to faithfully make digital elevation models with grid spacing smaller than 10cm. We adapt a geometric method that relies on a small number of user-dependent decisions to produce an offset estimate from a set of geomorphic markers (thalweg, channel margins, channel shoulders) from upstream and downstream locations. We typically derive an ensemble of at least 10 offset measurements per stream channel and from these calculate a mean and standard deviation. We also explore using gradient changes in long profiles of the offset stream reaches to diagnose the possibility of a ~10m channel experiencing 2 ~5m slip events. Preliminary results suggest a tendency towards the higher value offset estimates, although this does not necessarily preclude the possibility of two or more events causing the cumulative offset.

  9. Seismic Attenuation in the Parkfield area of the San Andreas Fault (United States)

    Kelly, C. M.; Rietbrock, A.; Faulkner, D. R.


    Fault zone structure and rock properties at depth within the Parkfield area of San Andreas Fault are investigated through a seismic attenuation study. Attenuation is sensitive to the degree of fracturing, water saturation and other rock properties. The Parkfield area is of interest as it marks the boundary between the creeping area of the San Andreas Fault and an area which ruptured seismically in 1966 and again in 2004. It is also the area of the SAFOD drilling project. Previous studies of this area have suggested a complex picture of fault strands linking at depth and small bodies of high-velocity material (e.g. Li et al. 1997, Michael & Eberhart-Philips 1991). Various temporary and local seismic networks have been installed in the region and data from the PASO, PASO TRES and HRSN networks are used in this study. PASO data runs from 2001-2002 at sampling rate of 100sps. The PASO TRES data spans the time period 2004-2006 at 200sps. The HRSN network has been running since March 2001 to present with sampling at 250sps. Attenuation parameters (e.g. Q-values) are established using the spectral ratios technique. A window of 1.28 seconds around each event arrival is extracted together with a window of the same length within the noise directly preceding. Instrument corrected frequency spectra from both the event and the noise are smoothed in a logarithmically-scaled smoothing function. Only frequencies with a signal/noise ratio of 3 or above are used. The ratio between frequency spectra from event arrivals and synthetic frequency spectra of known seismic parameters is determined. A gridsearch method is used to fit the event corner frequency, searching within a range of corner frequencies implied from the reported event magnitude and assuming a stress drop of between 0.1 and 10MPa. A Brune source model is assumed (gamma=2, n=1) for the source spectra (Brune 1970). When the correct corner frequency is fitted, there should be a linear relationship between frequency and the

  10. Subsurface geometry of the San Andreas-Calaveras fault junction: influence of serpentinite and the Coast Range Ophiolite (United States)

    Watt, Janet Tilden; Ponce, David A.; Graymer, Russell W.; Jachens, Robert C.; Simpson, Robert W.


    While an enormous amount of research has been focused on trying to understand the geologic history and neotectonics of the San Andreas-Calaveras fault (SAF-CF) junction, fundamental questions concerning fault geometry and mechanisms for slip transfer through the junction remain. We use potential-field, geologic, geodetic, and seismicity data to investigate the 3-D geologic framework of the SAF-CF junction and identify potential slip-transferring structures within the junction. Geophysical evidence suggests that the San Andreas and Calaveras fault zones dip away from each other within the northern portion of the junction, bounding a triangular-shaped wedge of crust in cross section. This wedge changes shape to the south as fault geometries change and fault activity shifts between fault strands, particularly along the Calaveras fault zone (CFZ). Potential-field modeling and relocated seismicity suggest that the Paicines and San Benito strands of the CFZ dip 65° to 70° NE and form the southwest boundary of a folded 1 to 3 km thick tabular body of Coast Range Ophiolite (CRO) within the Vallecitos syncline. We identify and characterize two steeply dipping, seismically active cross structures within the junction that are associated with serpentinite in the subsurface. The architecture of the SAF-CF junction presented in this study may help explain fault-normal motions currently observed in geodetic data and help constrain the seismic hazard. The abundance of serpentinite and related CRO in the subsurface is a significant discovery that not only helps constrain the geometry of structures but may also help explain fault behavior and the tectonic evolution of the SAF-CF junction.

  11. High-resolution seismic velocities and shallow structure of the San Andreas fault zone at Middle Mountain, Parkfield, California (United States)

    Catchings, R.D.; Rymer, M.J.; Goldman, M.R.; Hole, J.A.; Huggins, R.; Lippus, C.


    A 5-km-long, high-resolution seismic imaging survey across the San Andreas fault (SAF) zone and the proposed San Andreas Fault Observatory at Depth (SAFOD) drill site near Parkfield, California, shows that velocities vary both laterally and vertically. Velocities range from 4.0 km/sec) probably correspond to granitic rock of the Salinian block, which is exposed a few kilometers southwest of the SAF. The depth to the top of probable granitic rock varies laterally along the seismic profile but is about 600 m below the surface at the proposed SAFOD site. We observe a prominent, lateral low-velocity zone (LVZ) beneath and southwest of the surface trace of the SAF. The LVZ is about 1.5 km wide at 300-m depth but tapers to about 600 m wide at 750-m depth. At the maximum depth of the velocity model (750 m), the LVZ is centered approximately 400 m southwest of the surface trace of the SAF. Similar velocities and velocity gradients are observed at comparable depths on both sides of the LVZ, suggesting that the LVZ is anomalous relative to rocks on either side of it. Velocities within the LVZ are lower than those of San Andreas fault gouge, and the LVZ is also anomalous with respect to gravity, magnetic, and resistivity measurements. Because of its proximity to the surface trace of the SAF, it is tempting to suggest that the LVZ represents a zone of fractured crystalline rocks at depth. However, the LVZ instead probably represents a tectonic sliver of sedimentary rock that now rests adjacent to or encompasses the SAF. Such a sliver of sedimentary rock implies fault strands on both sides and possibly within the sliver, suggesting a zone of fault strands at least 1.5 km wide at a depth of 300 m, tapering to about 600 m wide at 750-m depth. Fluids within the sedimentary sliver are probably responsible for observed low-resistivity values.

  12. Spectral Analysis of Localized Stress Variations, the Spatial Distribution of Faults, and the Scaling of Physical Properties near the San Andreas Fault (United States)

    Day-Lewis, A.; Zoback, M. D.; Hickman, S. H.


    Statistical characterization of stress-induced wellbore failures and rock property heterogeneity from well logs offers potential insight into the scaling properties and mechanisms of stress heterogeneity. Wellbore breakouts identified in acoustic wellbore image data obtained adjacent to the San Andreas Fault, from both the San Andreas Fault Observatory at Depth (SAFOD) and the Cajon Pass Scientific Borehole, reveal multi-scale rotations in the direction of maximum horizontal compressive stress (SHmax) as a function of depth. Similar breakout rotations are frequently observed in other deep wellbores and, in most cases, reflect small variations in the directions and/or magnitudes of the in situ principal stresses superimposed on a relatively uniform regional stress state. To determine possible physical causes for these rotations, we employ spectral and statistical methods to investigate the relationships between the breakout rotations observed in our study wells and stress drops associated with slip on faults in highly fractured crust adjacent to a major fault zone. We also address the possible role of rock property variability as a controlling mechanism, taking into account drilling and data acquisition artifacts. We find that physical property heterogeneity in the SAFOD Pilot Hole behaves as self-similar, flicker noise (i.e., 1/f) over wavelengths from one meter to one kilometer, a result that agrees with similar investigations at Cajon Pass and a variety of other locations throughout the world. The stress orientations in both wells, however, exhibit behavior between that of flicker noise and Brownian motion over wavelengths from one decimeter to several kilometers, which is similar to how earthquake frequency has been shown to scale with fault size. The fractal scaling of observed stress heterogeneity appears to be more closely related to the distribution of faults in the crust adjacent to the study wells than to heterogeneity of elastic or other in-situ physical

  13. Rupture directivity of micro-earthquakes along the San Andreas fault (United States)

    Wang, E.; Rubin, A. M.


    Theoretically, it is expected that earthquakes occurring on an interface separating materials with different elastic properties might have a preferential rupture propagation direction. To test for this, we searched for indications of directivity by examining spectral ratios of multiple pairs of nearby earthquakes at azimuthally distributed seismic stations. By taking the spectral ratios, this technique is capable of canceling path and station terms in seismic spectra. It differs from a typical empirical Green's Function approach in that it compares events with similar sizes as well as events with significant size differences. The spectral ratios are fitted with a simple forward model, in which a bidirectional earthquake source is composed of two point sources moving at constant velocities in opposite directions (assumed to be horizontal). Each bidirectional earthquake has four model parameters: the lengths of the two rupture halves running in opposite directions, and their propagation velocities. A priori information concerning the total rupture length of bidirectional events are computed from catalog magnitude using a moment-magnitude relation and a 3MPa stress drop on an equidimensional rupture. The a priori rupture velocity is peaked at 0.8Vs and constrained to be smaller than Vs. Since identical earthquakes would produce frequency-independent spectral ratios at all azimuths, determining the initiation points of earthquakes requires variability in event size and/or relative directivity. The relocated catalog of Rubin [2002] was used to define 78 clusters of repeating earthquakes along the central San Andreas fault. The spectral ratios of all combinations of earthquake pairs in each cluster were fitted with synthetic spectral ratios at stations with sufficient signal-to-noise ratio and coherence. The inversion results show that, as might have been expected, differences in rupture processes (duration and relative directivity) of the earthquakes within most

  14. 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

    Energy Technology Data Exchange (ETDEWEB)

    Castillo, D. A., [Department of Geology and Geophysics, University of Adelaide (Australia); Younker, L.W. [Lawrence Livermore National Lab., CA (United States)


    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.

  15. Structure of the 1906 near-surface rupture zone of the San Andreas Fault, San Francisco Peninsula segment, near Woodside, California (United States)

    Rosa, C.M.; Catchings, R.D.; Rymer, M.J.; Grove, Karen; Goldman, M.R.


    High-resolution seismic-reflection and refraction images of the 1906 surface rupture zone of the San Andreas Fault near Woodside, California reveal evidence for one or more additional near-surface (within about 3 meters [m] depth) fault strands within about 25 m of the 1906 surface rupture. The 1906 surface rupture above the groundwater table (vadose zone) has been observed in paleoseismic trenches that coincide with our seismic profile and is seismically characterized by a discrete zone of low P-wave velocities (Vp), low S-wave velocities (Vs), high Vp/Vs ratios, and high Poisson’s ratios. A second near-surface fault strand, located about 17 m to the southwest of the 1906 surface rupture, is inferred by similar seismic anomalies. Between these two near-surface fault strands and below 5 m depth, we observed a near-vertical fault strand characterized by a zone of high Vp, low Vs, high Vp/Vs ratios, and high Poisson’s ratios on refraction tomography images and near-vertical diffractions on seismic-reflection images. This prominent subsurface zone of seismic anomalies is laterally offset from the 1906 surface rupture by about 8 m and likely represents the active main (long-term) strand of the San Andreas Fault at 5 to 10 m depth. Geometries of the near-surface and subsurface (about 5 to 10 m depth) fault zone suggest that the 1906 surface rupture dips southwestward to join the main strand of the San Andreas Fault at about 5 to 10 m below the surface. The 1906 surface rupture forms a prominent groundwater barrier in the upper 3 to 5 m, but our interpreted secondary near-surface fault strand to the southwest forms a weaker barrier, suggesting that there has been less or less-recent near-surface slip on that strand. At about 6 m depth, the main strand of the San Andreas Fault consists of water-saturated blue clay (collected from a hand-augered borehole), which is similar to deeply weathered serpentinite observed within the main strand of the San Andreas Fault at

  16. Scientific drilling into the San Andreas fault and site characterization research: Planning and coordination efforts. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Zoback, M.D.


    The fundamental scientific issue addressed in this proposal, obtaining an improved understanding of the physical and chemical processes responsible for earthquakes along major fault zones, is clearly of global scientific interest. By sampling the San Andreas fault zone and making direct measurements of fault zone properties to 4.0 km at Parkfield they will be studying an active plate-boundary fault at a depth where aseismic creep and small earthquakes occur and where a number of the scientific questions associated with deeper fault zone drilling can begin to be addressed. Also, the technological challenges associated with drilling, coring, downhole measurements and borehole instrumentation that may eventually have to be faced in deeper drilling can first be addressed at moderate depth and temperature in the Parkfield hole. Throughout the planning process leading to the development of this proposal they have invited participation by scientists from around the world. As a result, the workshops and meetings they have held for this project have involved about 350 scientists and engineers from about a dozen countries.

  17. Discovery Along the San Andreas Fault: Relocating Photographs From the 1906 Earthquake in San Francisco and San Mateo Counties (United States)

    Grove, K.; Prentice, C.; Polly, J.; Yuen, C.; Wu, K.; Zhong, S.; Lopez, J.


    April of 2006 will mark the 100-year anniversary of the great 1906 San Francisco earthquake. This earthquake was important not only because of its human tragedy (thousands of dead or homeless people), but also because of its scientific significance. The 8.3 magnitude earthquake ruptured 430 km of the northern San Andreas fault (SAF) and lasted nearly one minute. Investigations after the earthquake led to discoveries that were the beginning of modern earthquake theories and measuring instruments. This was also one of the first large-scale natural disasters to be photographed. Our research group, which is part of the National Science Foundation funded SF-ROCKS program, acquired photographs that were taken shortly after the earthquake in downtown San Francisco and along the SAF in San Mateo County. The SAF photos are part of a Geographical Information System (GIS) database being published on a U.S. Geological Survey web site. The goal of our project was to improve estimates of photograph locations and to compare the landscape features that were visible after the earthquake with the landscape that we see today. We used the GIS database to find initial photo locations, and we then used a high-precision Global Positioning System (GPS) to measure the geographic coordinates of the locations once we matched our view to what we saw in a photo. Where possible, we used a digital camera to retake photos from the same position, to show the difference in the landscape 100 years later. The 1906 photos show fault zone features such as ground rupture, sag ponds, shutter ridges, and offset fences. Changes to the landscape since 1906 have included erosion and grading of the land, building of houses and other structures, and more tree cover compared to previous grassland vegetation. Our project is part of 1906 Earthquake Centennial activities; it is contributing to the photo archive that helps scientists and engineers who study earthquakes and their effects. It will also help the

  18. Depth-Dependent Low-Velocity Structure of the San Andreas Fault near the SAFOD Drilling Site at Parkfield from Fault-Zone Seismic Waves (United States)

    Alvarez, M.; Li, Y.; Vidale, J.; Cochran, E.


    Coordinated by the SAFOD PIs, we used 96 PASSCAL short-period three-component seismometers in linear arrays deployed across and along the San Andreas fault (SAF) near the town of Parkfield and the SAFOD drilling site in 2002 and 2003, respectively. The data recorded for near-surface explosions detonated in the experiments (Li and Vidale), PASO project (Thurber and Roecker) and refraction profiling (Hole), and local earthquakes show fault-zone trapped waves clearly for the source and receivers located close to the fault. The time duration of the dominant trapped energy after S-arrivals increases with the event-to-array distance and focal depth progressively. Using a finite-difference code, we first synthesize fault-zone trapped waves generated by explosions to determine the shallowest 1 or 2 km fault zone structure with the velocity constraints from seismic profiling of the shallow SAF at Parkfield [Catchings et al., 2002]. We then strip shallow effects to resolve deeper structure of the fault zone, and synthesize trapped waves from earthquakes at depths between 2.5 and 11 km to complete a model of the SAF with depth-variable structure in 3-D. We also use the P-first arrivals and polarity as additional information in modeling of velocities and location of the material interface with the structural constraints from seismic tomography at Parkfield [Thurber et al., 2004] to the bed-rock velocities. In grid-search modeling, we tested various values for fault zone depth, width, velocity, Q, and source location. The best-fit model parameters from this study show evidence of a damaged core zone on the main SAF, which likely extends to seismogenic depths. The zone is marked by a low-velocity waveguide ~150 m wide, in which Q is 10-50 and shear velocities are reduced by 30-45% from wall-rock velocities. We also find some seismic energy trapped partitioned in the branching faults that connect to the San Andreas main fault at a shallow depth near Parkfield.

  19. New constraints on the geometry and evolution of the Southern San Andreas Fault and Salton Pull-apart basin (United States)

    Sahakian, V. J.; Holmes, J. J.; Kell, A. M.; Harding, A. J.; Driscoll, N. W.; Kent, G.


    In the recent geologic past, the Salton pull-apart basin, northern Imperial Fault (IF) and Southern San Andreas Fault (SSAF) have been part of an evolving tectonic regime, subject to strain partitioning. This part of the North American/Pacific plate boundary has the potential for generating a large earthquake. Several lines of active-source seismic reflection and refraction data in the Salton Sea were analyzed to better understand the fault interactions and evolution in this region by investigating the SSAF geometry, stratigraphy, and velocity structure. These data, collected in conjunction with the Salton Seismic Imaging Project (SSIP) include two fault-perpendicular lines: one adjacent to the southern terminus of the SSAF (Line 7), and one just south of the terminus (Line 8). We present results from Multi Channel Seismic (MCS) data along Line 7, and refraction data along Lines 7 and 8. Velocity models along these lines were constructed from the refraction data. Included in the Line 7 model is an interface representing a strong reflector observed in the MCS data, which helps to constrain the raypaths and velocities in the model. Line 7 MCS data image stratigraphic layers thickening to and dipping down to the east towards the SSAF, indicative of a westward-dipping, oblique strike-slip fault. The refraction data along this line are consistent with a westward dipping SSAF and a down the west normal component. We present velocity models for Line 7 and 8, as well as resolution tests supporting the fault's geometry. The results from these two lines and a fault parallel line suggest that the SSAF is dipping to the west and is in transtension. We propose that the SSAF has migrated northward through time, partitioning its strain onto the IF. As the IF migrates northwards it forms the Salton pull-apart basin.

  20. Human-induced uplift of the Sierra Nevada Mountains and seismicity modulation on the San Andreas Fault (United States)

    Amos, Colin; Audet, Pascal; Hammond, William C.; Burgmann, Roland; Johanson, Ingrid A.; Blewitt, Geoffrey


    We investigate the cause of geodetically observed mountain uplift in the Sierra Nevada, western US. In the process, we reveal a possible human-induced mechanism that may be driving Sierra Nevada uplift, and may also be pushing the San Andreas Fault closer to failure. An initial study of the Sierra Nevada [Hammond et al., Geology, 40, 2012] exploited the complementary strengths of point positions from GPS and blanket coverage measurements from InSAR, to show that contemporary vertical motion of the Sierra Nevada is between 1 - 2 mm/yr relative to the comparatively stable Great Basin to the east. One possible interpretation of this is that the most modern episode of tectonic uplift is still active in the Sierra Nevada. However, we now discover that GPS stations surrounding the southern San Joaquin Valley in California show a pattern of uplift concentrated not only in the Sierra Nevada to the east, but more broadly along the basin margins, including the adjacent central Coast Range to the west. Peak vertical velocities reach values up to 1 - 3 mm/yr. This suggests the San Joaquin Valley plays a key role in the uplift of the Sierra Nevada to the east, with possible implications for the San Andreas Fault to the west. Anthropogenic groundwater depletion in the southern San Joaquin Valley has been massive and sustained, therefore hydrological loading variation might explain contemporary uplift. To test this, we apply a simple elastic model that uses a line load centered along the valley axis, a range of elastic parameters, and published estimates of the integrated rate of mass loss due to groundwater removal over the last decade. Predicted uplift centered along the valley axis matches well with patterns of GPS motion, with the upward vertical rates decaying away from the valley margins. Observed seasonal variability in the vertical GPS positions lends support for this model, showing peak uplift for stations surrounding the valley during the dry summer and fall months. On

  1. Seismic Documentation for Rock Damage and Heal on the San Andreas Fault Involved in the 2004 M6 Parkfield Earthquake (United States)

    Malin, P. M.; Li, Y.; Chen, P.; Cochran, E. M.; Vidale, J. E.


    After the M6 Parkfield earthquake that occurred on 28 September 2004, we deployed a dense seismic array at the same sites as used in our experiment in the fall of 2002. The measurements using moving-window cross- correlation of waveforms for the repeated explosions and microearthquakes recorded in 2002 and 2004 show a decrease in shear velocity of at least ~2.5% within a ~200-m-wide zone across the San Andreas main fault trace most likely owing to co-seismic damage of fault rocks caused by dynamic rupture in this M6 earthquake. The width of the damage zone characterized by larger velocity changes is consistent with the low-velocity waveguide model on the SAF near Parkfield derived from fault-zone trapped waves [Li et al., 2004]. The estimated ratio between the P and S wave traveltime changes is 0.57 within the rupture zone and ~0.65 in the surrounding rocks, indicating wetter cracks within the damaged fault zone, probably due to the ground water percolating into the cracks opened in the mainshock. The measurements of traveltime changes for repeated aftershocks in 21 clusters, with a total of ~130 events, located at different depths along the rupture in 2004 show that the maximum shear velocity increased by ~1.2% within the damage zone in 3.5 months starting a week after the mainshock, indicating that the fault heals in the post-seismic stage due to the closure of cracks in the damaged rock. The data recorded at a seismograph installed in the SAFOD mainhole passing the San Andreas fault zone at ~3-km depths for repeated aftershocks in December of 2004 and later show that seismic velocities within the damage zone were changed by ~0.3% in a month, but no changes were registered at seismographs installed in the vertical pilot borehole drilled ~1.8 km away from the main fault trace for the same repeated events. We find that the healing rate is logarithmically decreasing through time with greater healing rate in the earlier stage after the mainshock. The magnitude of

  2. Long-term slip rate of the southern San Andreas Fault, from 10Be-26Al surface exposure dating of an offset alluvial fan

    Energy Technology Data Exchange (ETDEWEB)

    der Woerd, J v; Klinger, Y; Sieh, K; Tapponnier, P; Ryerson, F; M?riaux, A


    We determine the long-term slip rate of the southern San Andreas Fault in the southeastern Indio Hills using {sup 10}Be and {sup 26}Al isotopes to date an offset alluvial fan surface. Field mapping complemented with topographic data, air photos and satellite images allow to precisely determine piercing points across the fault zone that are used to measure an offset of 565 {+-} 80 m. A total of twenty-six quartz-rich cobbles from three different fan surfaces were collected and dated. The tight cluster of nuclide concentrations from 19 samples out of 20 from the offset fan surface implies a simple exposure history, negligible prior exposure and erosion, and yield an age of 35.5 {+-} 2.5 ka. The long-term slip rate of the San Andreas Fault south of Biskra Palms is thus 15.9 {+-} 3.4 mm/yr. This rate is about 10 mm/yr slower than geological (0-14 ka) and short-term geodetic estimates for this part of the San Andreas Fault implying changes in slip rate or in faulting behavior. This result puts new constraints on the slip rate of the San Jacinto and on the Eastern California Shear Zone for the last 35 ka. Our study shows that more sites along the major faults of southern California need to be targeted to better constrain the slip-rates over different time scales.

  3. Trees as indicators of past movements on the San Andreas Fault (United States)

    Wallace, R.E.; LaMarche, Valmore C.


    Trees are sources of information about fault movements that have occurred before the earliest historical reports. This kind of evidence can be used to improve estimates of when earthquakes will recur on faults known to be seismically active and to identify active faults that have no record of movement during recent history.

  4. Along-strike variations in fault frictional properties along the San Andreas Fault near Cholame, California from joint earthquake and low-frequency earthquake relocations (United States)

    Harrington, Rebecca M.; Cochran, Elizabeth S.; Griffiths, Emily M.; Zeng, Xiangfang; Thurber, Clifford H.


    Recent observations of low‐frequency earthquakes (LFEs) and tectonic tremor along the Parkfield–Cholame segment of the San Andreas fault suggest slow‐slip earthquakes occur in a transition zone between the shallow fault, which accommodates slip by a combination of aseismic creep and earthquakes (fault, which accommodates slip by stable sliding (>35  km depth). However, the spatial relationship between shallow earthquakes and LFEs remains unclear. Here, we present precise relocations of 34 earthquakes and 34 LFEs recorded during a temporary deployment of 13 broadband seismic stations from May 2010 to July 2011. We use the temporary array waveform data, along with data from permanent seismic stations and a new high‐resolution 3D velocity model, to illuminate the fine‐scale details of the seismicity distribution near Cholame and the relation to the distribution of LFEs. The depth of the boundary between earthquakes and LFE hypocenters changes along strike and roughly follows the 350°C isotherm, suggesting frictional behavior may be, in part, thermally controlled. We observe no overlap in the depth of earthquakes and LFEs, with an ∼5  km separation between the deepest earthquakes and shallowest LFEs. In addition, clustering in the relocated seismicity near the 2004 Mw 6.0 Parkfield earthquake hypocenter and near the northern boundary of the 1857 Mw 7.8 Fort Tejon rupture may highlight areas of frictional heterogeneities on the fault where earthquakes tend to nucleate.

  5. Automatic identification of fault zone head waves and direct P waves and its application in the Parkfield section of the San Andreas Fault, California (United States)

    Li, Zefeng; Peng, Zhigang


    Fault zone head waves (FZHWs) are observed along major strike-slip faults and can provide high-resolution imaging of fault interface properties at seismogenic depth. In this paper, we present a new method to automatically detect FZHWs and pick direct P waves secondary arrivals (DWSAs). The algorithm identifies FZHWs by computing the amplitude ratios between the potential FZHWs and DSWAs. The polarities, polarizations and characteristic periods of FZHWs and DSWAs are then used to refine the picks or evaluate the pick quality. We apply the method to the Parkfield section of the San Andreas Fault where FZHWs have been identified before by manual picks. We compare results from automatically and manually picked arrivals and find general agreement between them. The obtained velocity contrast at Parkfield is generally 5-10 per cent near Middle Mountain while it decreases below 5 per cent near Gold Hill. We also find many FZHWs recorded by the stations within 1 km of the background seismicity (i.e. the Southwest Fracture Zone) that have not been reported before. These FZHWs could be generated within a relatively wide low velocity zone sandwiched between the fast Salinian block on the southwest side and the slow Franciscan Mélange on the northeast side. Station FROB on the southwest (fast) side also recorded a small portion of weak precursory signals before sharp P waves. However, the polarities of weak signals are consistent with the right-lateral strike-slip mechanisms, suggesting that they are unlikely genuine FZHW signals.

  6. TremorScope: A Tool to Image the Deep Workings of the San Andreas Fault near Cholame, CA (United States)

    Hellweg, M.; Burgmann, R.; Taira, T.; Nadeau, R. M.; Dreger, D. S.; Allen, R. M.


    Until recently, active fault zones were thought to deform via seismic slip during earthquakes in the upper, brittle portion of the crust, and by steady, aseismic shear below. However, since 2000, this view has been shaken by seismological observations of seismic tremor deep in the roots of active fault zones, including on the section of the San Andreas to the southeast of Parkfield, CA, deep (~20-30 km) beneath the nucleation zone of the great 1857 Fort Tejon earthquake. With funding from the Gordon and Betty Moore Foundation, we have improved the seismic network in the area above the tremor source by installing four new broadband/strong motion surface stations and four borehole sites with uphole accelerometers and downhole geophones, broadband and strong motion sensors. Data from all stations are telemetered in real-time. They are analysed as part of normal earthquake monitoring, and archived and distributed through the Northern California Earthquake Data Center (NCEDC). Data from the TremorScope project is improving earthquake monitoring in the region south of Parkfield, including allowing empirical Greens function finite fault analysis of moderate events in the area. Locations and characterization of tremor episodes are improved by the data recorded by TremorScope stations. For example, the rate of ambient tremor activity in the TremorScope area increased by a factor of ~8 within ~12 hours of the 2014 Napa M6.0 earthquake and remained elevated for ~ 100 days, exceeding the tremor rate increase following the 2004 Parkfield M6.0 quake despite the differences in epicentral distance (~300 km vs. ~15 km). No comparable increases in tremor rates have been observed between the Parkfield and Napa events. This suggests that the sensitivity to external stressing in the in the deep tremor zone of the TremorScope region may have increased since 2004. We also show how this network's strong motion instrumentation will provide unprecedented and exciting insights into the

  7. Along-strike variations in fault frictional properties along the San Andreas Fault near Cholame, California from joint earthquake and low-frequency earthquake relocations (United States)

    Harrington, R.M; Cochran, Elizabeth S.; Griffiths, E.M.; Zeng, X.; Thurber, C.


    Recent observations of low‐frequency earthquakes (LFEs) and tectonic tremor along the Parkfield–Cholame segment of the San Andreas fault suggest slow‐slip earthquakes occur in a transition zone between the shallow fault, which accommodates slip by a combination of aseismic creep and earthquakes (35  km depth). However, the spatial relationship between shallow earthquakes and LFEs remains unclear. Here, we present precise relocations of 34 earthquakes and 34 LFEs recorded during a temporary deployment of 13 broadband seismic stations from May 2010 to July 2011. We use the temporary array waveform data, along with data from permanent seismic stations and a new high‐resolution 3D velocity model, to illuminate the fine‐scale details of the seismicity distribution near Cholame and the relation to the distribution of LFEs. The depth of the boundary between earthquakes and LFE hypocenters changes along strike and roughly follows the 350°C isotherm, suggesting frictional behavior may be, in part, thermally controlled. We observe no overlap in the depth of earthquakes and LFEs, with an ∼5  km separation between the deepest earthquakes and shallowest LFEs. In addition, clustering in the relocated seismicity near the 2004 Mw 6.0 Parkfield earthquake hypocenter and near the northern boundary of the 1857 Mw 7.8 Fort Tejon rupture may highlight areas of frictional heterogeneities on the fault where earthquakes tend to nucleate.

  8. Hydrothermal frictional strengths of rock and mineral samples relevant to the creeping section of the San Andreas Fault (United States)

    Moore, Diane E.; Lockner, David A.; Hickman, Stephen H.


    We compare frictional strengths in the temperature range 25–250 °C of fault gouge from SAFOD (CDZ and SDZ) with quartzofeldspathic wall rocks typical of the central creeping section of the San Andreas Fault (Great Valley sequence and Franciscan Complex). The Great Valley and Franciscan samples have coefficients of friction, μ > 0.35 at all experimental conditions. Strength is unchanged between 25° and 150 °C, but μ increases at higher temperatures, exceeding 0.50 at 250 °C. Both samples are velocity strengthening at room temperature but show velocity-weakening behavior beginning at 150 °C and stick-slip motion at 250 °C. These rocks, therefore, have the potential for unstable seismic slip at depth. The CDZ gouge, with a high saponite content, is weak (μ = 0.09–0.17) and velocity strengthening in all experiments, and μ decreases at temperatures above 150 °C. Behavior of the SDZ is intermediate between the CDZ and wall rocks: μ < 0.2 and does not vary with temperature. Although saponite is probably not stable at depths greater than ∼3 km, substitution of the frictionally similar minerals talc and Mg-rich chlorite for saponite at higher temperatures could potentially extend the range of low strength and stable slip down to the base of the seismogenic zone.

  9. Paleoseismic investigations in the Santa Cruz mountains, California: Implications for recurrence of large-magnitude earthquakes on the San Andreas Fault (United States)

    Schwartz, D. P.; Pantosti, D.; Okumura, K.; Powers, T. J.; Hamilton, J. C.


    Trenching, microgeomorphic mapping, and tree ring analysis provide information on timing of paleoearthquakes and behavior of the San Andreas fault in the Santa Cruz mountains. At the Grizzly Flat site alluvial units dated at 1640-1659 A.D., 1679-1894 A.D., 1668-1893 A.D., and the present ground surface are displaced by a single event. This was the 1906 surface rupture. Combined trench dates and tree ring analysis suggest that the penultimate event occurred in the mid-1600 s, possibly in an interval as narrow as 1632-1659 A.D. There is no direct evidence in the trenches for the 1838 or 1865 earthquakes, which have been proposed as occurring on this part of the fault zone. In a minimum time of about 340 years only one large surface faulting event (1906) occurred at Grizzly Flat, in contrast to previous recurrence estimates of 95-110 years for the Santa Cruz mountains segment. Comparison with dates of the penultimate San Andreas earthquake at sites north of San Francisco suggests that the San Andreas fault between Point Arena and the Santa Cruz mountains may have failed either as a sequence of closely timed earthquakes on adjacent segments or as a single long rupture similar in length to the 1906 rupture around the mid-1600 s. The 1906 coseismic geodetic slip and the late Holocene geologic slip rate on the San Francisco peninsula and southward are about 50-70% and 70% of their values north of San Francisco, respectively. The slip gradient along the 1906 rupture section of the San Andreas reflects partitioning of plate boundary slip onto the San Gregorio, Sargent, and other faults south of the Golden Gate. If a mid-1600 s event ruptured the same section of the fault that failed in 1906, it supports the concept that long strike-slip faults can contain master rupture segments that repeat in both length and slip distribution. Recognition of a persistent slip rate gradient along the northern San Andreas fault and the concept of a master segment remove the requirement that

  10. Fault Tolerant Control Systems

    DEFF Research Database (Denmark)

    Bøgh, S.A.

    and isolation, remedial action decision, and reconfiguration. The integration of these modules in software were considered. The general methodology covered the analysis, design, and implementation of fault tolerant control systems on an overall level. Two detailed studies were presented, one on fault detection......, as for example a variable being zero, low or high. Examples were given that illustrate how such models can be established by simple means, and yet provide important information when combined into a complete system. A special achievement was a method to determine how control loops behave in case of faults......This thesis considered the development of fault tolerant control systems. The focus was on the category of automated processes that do not necessarily comprise a high number of identical sensors and actuators to maintain safe operation, but still have a potential for improving immunity to component...

  11. Three-Dimensional Investigation of a 5 m Deflected Swale along the San Andreas Fault in the Carrizo Plain

    KAUST Repository

    Akciz, S. O.


    Topographic maps produced from Light Detection and Ranging (LiDAR) data are useful for paleoseismic and neotectonic research because they provide submeter representation of faulting-related surface features. Offset measurements of geomorphic features, made in the field or on a remotely sensed imagery, commonly assume a straight or smooth (i.e., undeflected) pre-earthquake geometry. Here, we present results from investigation of an ∼20 cm deep and >5 m wide swale with a sharp bend along the San Andreas fault (SAF) at the Bidart fan site in the Carrizo Plain, California. From analysis of LiDAR topography images and field measurements, the swale was initially interpreted as a channel tectonically offset ∼4:7 m. Our observations from exposures in four backhoe excavations and 25 hand-dug trenchettes show that even though a sharp bend in the swale coincides with the trace of the A.D. 1857 fault rupture, the swale formed after the 1857 earthquake and was not tectonically offset. Subtle fractures observed within a surficial gravel unit overlying the 1857 rupture trace are similar to fractures previously documented at the Phelan fan and LY4 paleoseismic sites 3 and 35 km northwest of Bidart fan, respectively. Collectively, the fractures suggest that a post-1857 moderate-magnitude earthquake caused ground cracking in the Carrizo and Cholame stretches of the SAF. Our observations emphasize the importance of excavation at key locations to validate remote and ground-based measurements, and we advocate more geomorphic characterization for each site if excavation is not possible.

  12. The microstructural character and evolution of fault rocks from the SAFOD core and potential weakening mechanisms along the San Andreas Fault (Invited) (United States)

    Holdsworth, R. E.; van Diggelen, E.; Spiers, C.; de Bresser, J. H.; Smith, S. A.


    In the region of the SAFOD borehole, the San Andreas Fault (SAF) separates two very different geological terranes referred to here as the Salinian and Great Valley blocks (SB, GVB). The three sections of core preserve a diverse range of fault rocks and pass through the two currently active, highly localised slipping sections, the so-called ‘10480’ and ‘10830’ fault zones . These coincide with a broader region - perhaps as much as 100m wide - of high strain fault rocks formed at some time in the geological past, but now currently inactive. Both the slipping segments and older high strain zone(s) are developed in the GVB located NE of the terrane boundary. This is likely influenced by the phyllosilicate-rich protolith of the GVB and the large volume of trapped fluid known to exist NE and below the SAF in this region. Microstructurally, lower strain domains (most of Core 1 cutting the SB, significant parts of Core 3 cutting the GVB) preserve clear evidence for classic upper crustal cataclastic brittle faulting processes and associated fluid flow. The GVB in particular shows clear geological evidence for both fluid pressure and differential stress cycling (variable modes of hydrofacture associated with faults) during seismicity. There is also some evidence in all minor faults for the operation of limited amounts of solution-precipitation creep. High strain domains (much of Core 2 cutting the GVB, parts of Core 3 adjacent to the 10830 fault) are characterised by the development of foliated cataclasites and gouge largely due to the new growth of fine-grained phyllosilicate networks (predominantly smectite-bearing mixed layer clays, locally serpentinite, but not talc). The most deformed sections are characterised by the development of shear band fabrics and asymmetric folds. Reworking and reactivation is widespread manifested by: i) the preservation of one or more earlier generations of gouge preserved as clasts; and ii) by the development of later interconnected

  13. Locating non-volcanic tremor along the San Andreas Fault using a multiple array source imaging technique (United States)

    Ryberg, T.; Haberland, C.H.; Fuis, G.S.; Ellsworth, W.L.; Shelly, D.R.


    Non-volcanic tremor (NVT) has been observed at several subduction zones and at the San Andreas Fault (SAF). Tremor locations are commonly derived by cross-correlating envelope-transformed seismic traces in combination with source-scanning techniques. Recently, they have also been located by using relative relocations with master events, that is low-frequency earthquakes that are part of the tremor; locations are derived by conventional traveltime-based methods. Here we present a method to locate the sources of NVT using an imaging approach for multiple array data. The performance of the method is checked with synthetic tests and the relocation of earthquakes. We also applied the method to tremor occurring near Cholame, California. A set of small-aperture arrays (i.e. an array consisting of arrays) installed around Cholame provided the data set for this study. We observed several tremor episodes and located tremor sources in the vicinity of SAF. During individual tremor episodes, we observed a systematic change of source location, indicating rapid migration of the tremor source along SAF. ?? 2010 The Authors Geophysical Journal International ?? 2010 RAS.

  14. Fault detection and isolation in systems with parametric faults

    DEFF Research Database (Denmark)

    Stoustrup, Jakob; Niemann, Hans Henrik


    The problem of fault detection and isolation of parametric faults is considered in this paper. A fault detection problem based on parametric faults are associated with internal parameter variations in the dynamical system. A fault detection and isolation method for parametric faults is formulated...

  15. Geophysical Surveys of the San Andreas and Crystal Springs Reservoir System Including Seismic-Reflection Profiles and Swath Bathymetry, San Mateo County, California (United States)

    Finlayson, David P.; Triezenberg, Peter J.; Hart, Patrick E.


    This report describes geophysical data acquired by the U.S. Geological Survey (USGS) in San Andreas Reservoir and Upper and Lower Crystal Springs Reservoirs, San Mateo County, California, as part of an effort to refine knowledge of the location of traces of the San Andreas Fault within the reservoir system and to provide improved reservoir bathymetry for estimates of reservoir water volume. The surveys were conducted by the Western Coastal and Marine Geology (WCMG) Team of the USGS for the San Francisco Public Utilities Commission (SFPUC). The data were acquired in three separate surveys: (1) in June 2007, personnel from WCMG completed a three-day survey of San Andreas Reservoir, collecting approximately 50 km of high-resolution Chirp subbottom seismic-reflection data; (2) in November 2007, WCMG conducted a swath-bathymetry survey of San Andreas reservoir; and finally (3) in April 2008, WCMG conducted a swath-bathymetry survey of both the upper and lower Crystal Springs Reservoir system. Top of PageFor more information, contact David Finlayson.

  16. Gravity constraints on the geometry of the Big Bend of the San Andreas Fault in the southern Carrizo Plains and Pine Mountain egion (United States)

    Altintas, Ali Can

    The goal of this project is to combine gravity measurements with geologic observations to better understand the "Big Bend" of the San Andreas Fault (SAF) and its role in producing hydrocarbon-bearing structures in the southern Central Valley of California. The SAF is the main plate boundary structure between the Pacific and North American plates and accommodates ?35 mm/yr of dextral motion. The SAF can be divided into three main parts: the northern, central and southern segments. The boundary between the central and southern segments is the "Big Bend", which is characterized by an ≈30°, eastward bend. This fault curvature led to the creation of a series of roughly east-west thrust faults and the transverse mountain ranges. Four high-resolution gravity transects were conducted across locations on either side of the bend. A total of 166 new gravity measurements were collected. Previous studies suggest significantly inclined dip angle for the San Andreas Fault in the Big Bend area. Yet, our models indicate that the San Andreas Fault is near vertical in the Big Bend area. Also gravity cross-section models suggest that flower structures occur on either side of the bend. These structures are dominated by sedimentary rocks in the north and igneous rocks in the south. The two northern transects in the Carrizo plains have an ≈-70 mgal Bouguer anomaly. The SAF has a strike of ≈315° near these transects. The northern transects are characterized by multiple fault strands which cut marine and terrestrial Miocene sedimentary rocks as well as Quaternary alluvial valley deposits. These fault strands are characterized by ?6 mgal short wavelength variations in the Bouguer gravity anomaly, which correspond to low density fault gouge and fault splays that juxtapose rocks of varying densities. The southern transects cross part of the SAF with a strike of 285°, have a Bouguer anomaly of ≈-50 mgal and are characterized by a broad 15 mgal high. At this location the rocks on

  17. A reevaluation of the Pallett Creek earthquake chronology based on new AMS radiocarbon dates, San Andreas fault, California (United States)

    Scharer, K.M.; Biasi, G.P.; Weldon, R.J.


    The Pallett Creek paleoseismic record occupies a keystone position in most attempts to develop rupture histories for the southern San Andreas fault. Previous estimates of earthquake ages at Pallett Creek were determined by decay counting radiocarbon methods. That method requires large samples which can lead to unaccounted sources of uncertainty in radiocarbon ages because of the heterogeneous composition of organic layers. In contrast, accelerator mass spectrometry (AMS) radiocarbon dates may be obtained from small samples that have known carbon sources and also allow for a more complete sampling of the section. We present 65 new AMS radiocarbon dates that span nine ground-rupturing earthquakes at Pallett Creek. Overall, the AMS dates are similar to and reveal no dramatic bias in the conventional dates. For many layers, however, individual charcoal samples were younger than the conventional dates, leading to earthquake ages that are overall slightly younger than previously reported. New earthquake ages are determined by Bayesian refinement of the layer ages based on stratigraphic ordering and sedimentological constraints. The new chronology is more regular than previously published records in large part due to new samples constraining the age of event R. The closed interval from event C to 1857 has a mean recurrence of 135years (?? = 83.2 years) and a quasiperiodic coefficient of variation (COV) of 0.61. We show that the new dates and resultant earthquake chronology have a stronger effect on COV than the specific membership of this long series and dating precision improvements from sedimentation rates. Copyright 2011 by the American Geophysical Union.

  18. Orientation of three-component geophones in the San Andreas Fault observatory at depth Pilot Hole, Parkfield, California (United States)

    Oye, V.; Ellsworth, W.L.


    To identify and constrain the target zone for the planned SAFOD Main Hole through the San Andreas Fault (SAF) near Parkfield, California, a 32-level three-component (3C) geophone string was installed in the Pilot Hole (PH) to monitor and improve the locations of nearby earthquakes. The orientation of the 3C geophones is essential for this purpose, because ray directions from sources may be determined directly from the 3D particle motion for both P and S waves. Due to the complex local velocity structure, rays traced from explosions and earthquakes to the PH show strong ray bending. Observed azimuths are obtained from P-wave polarization analysis, and ray tracing provides theoretical estimates of the incoming wave field. The differences between the theoretical and the observed angles define the calibration azimuths. To investigate the process of orientation with respect to the assumed velocity model, we compare calibration azimuths derived from both a homogeneous and 3D velocity model. Uncertainties in the relative orientation between the geophone levels were also estimated for a cluster of 36 earthquakes that was not used in the orientation process. The comparison between the homogeneous and the 3D velocity model shows that there are only minor changes in these relative orientations. In contrast, the absolute orientations, with respect to global North, were significantly improved by application of the 3D model. The average data residual decreased from 13?? to 7??, supporting the importance of an accurate velocity model. We explain the remaining residuals by methodological uncertainties and noise and with errors in the velocity model.

  19. Active Fault Isolation in MIMO Systems

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Poulsen, Niels Kjølstad


    Active fault isolation of parametric faults in closed-loop MIMO system s are considered in this paper. The fault isolation consists of two steps. T he first step is group- wise fault isolation. Here, a group of faults is isolated from other pos sible faults in the system. The group-wise fault iso...

  20. Volatile fluxes through the Big Bend section of the San Andreas Fault, California: helium and carbon-dioxide systematics (United States)

    Kulongoski, Justin T.; Hilton, David R.; Barry, Peter H.; Esser, Bradley K.; Hillegonds, Darren; Belitz, Kenneth


    To investigate the source of volatiles and their relationship to the San Andreas Fault System (SAFS), 18 groundwater samples were collected from wells near the Big Bend section of the SAFS in southern California and analyzed for helium and carbon abundance and isotopes. Concentrations of 4He, corrected for air-bubble entrainment, vary from 4.15 to 62.7 (× 10− 8) cm3 STP g− 1 H2O. 3He/4He ratios vary from 0.09 to 3.52 RA (where RA = air 3He/4He), consistent with up to 44% mantle helium in samples. A subset of 10 samples was analyzed for the major volatile phase (CO2) — the hypothesized carrier phase of the helium in the mantle–crust system: CO2/3He ratios vary from 0.614 to 142 (× 1011), and δ13C (CO2) values vary from − 21.5 to − 11.9‰ (vs. PDB). 3He/4He ratios and CO2 concentrations are highest in the wells located in the Mil Potrero and Cuddy valleys adjacent to the SAFS. The elevated 3He/4He ratios are interpreted to be a consequence of a mantle volatile flux though the SAFS diluted by radiogenic He produced in the crust. Samples with the highest 3He/4He ratios also had the lowest CO2/3He ratios. The combined helium isotope, He–CO2 elemental relationships, and δ13C (CO2) values of the groundwater volatiles reveal a mixture of mantle and deep crustal (metamorphic) fluid origins. The flux of fluids into the seismogenic zone at high hydrostatic pressure may cause fault rupture, and transfer volatiles into the shallow crust. We calculate an upward fluid flow rate of 147 mm a− 1 along the SAFS, up to 37 times higher than previous estimates (Kennedy et al., 1997). However, using newly identified characteristics of the SAFS, we calculate a total flux of 3He along the SAFS of 7.4 × 103 cm3 STP a− 1 (0.33 mol 3He a− 1), and a CO2 flux of 1.5 × 1013 cm3STP a− 1 (6.6 × 108 mol a− 1), ~ 1% of previous estimates. Lower fluxes along the Big Bend section of the SAFS suggest that the flux of mantle volatiles alone is insufficient to cause the

  1. Seismic evidence for rock damage and healing on the San Andreas fault associated with the 2004 M 6.0 Parkfield earthquake (United States)

    Li, Y.-G.; Chen, P.; Cochran, E.S.; Vidale, J.E.; Burdette, T.


    We deployed a dense linear array of 45 seismometers across and along the San Andreas fault near Parkfield a week after the M 6.0 Parkfield earthquake on 28 September 2004 to record fault-zone seismic waves generated by aftershocks and explosions. Seismic stations and explosions were co-sited with our previous experiment conducted in 2002. The data from repeated shots detonated in the fall of 2002 and 3 months after the 2004 M 6.0 mainshock show ???1.0%-1.5% decreases in seismic-wave velocity within an ???200-m-wide zone along the fault strike and smaller changes (0.2%-0.5%) beyond this zone, most likely due to the coseismic damage of rocks during dynamic rupture in the 2004 M 6.0 earthquake. The width of the damage zone characterized by larger velocity changes is consistent with the low-velocity waveguide model on the San Andreas fault, near Parkfield, that we derived from fault-zone trapped waves (Li et al., 2004). The damage zone is not symmetric but extends farther on the southwest side of the main fault trace. Waveform cross-correlations for repeated aftershocks in 21 clusters, with a total of ???130 events, located at different depths and distances from the array site show ???0.7%-1.1% increases in S-wave velocity within the fault zone in 3 months starting a week after the earthquake. The velocity recovery indicates that the damaged rock has been healing and regaining the strength through rigidity recovery with time, most likely . due to the closure of cracks opened during the mainshock. We estimate that the net decrease in seismic velocities within the fault zone was at least ???2.5%, caused by the 2004 M 6.0 Parkfield earthquake. The healing rate was largest in the earlier stage of the postmainshock healing process. The magnitude of fault healing varies along the rupture zone, being slightly larger for the healing beneath Middle Mountain, correlating well with an area of large mapped slip. The fault healing is most prominent at depths above ???7 km.

  2. Estimating earthquake-rupture rates on a fault or fault system (United States)

    Field, E.H.; Page, M.T.


    Previous approaches used to determine the rates of different earthquakes on a fault have made assumptions regarding segmentation, have been difficult to document and reproduce, and have lacked the ability to satisfy all available data constraints. We present a relatively objective and reproducible inverse methodology for determining the rate of different ruptures on a fault or fault system. The data used in the inversion include slip rate, event rate, and other constraints such as an optional a priori magnitude-frequency distribution. We demonstrate our methodology by solving for the long-term rate of ruptures on the southern San Andreas fault. Our results imply that a Gutenberg-Richter distribution is consistent with the data available for this fault; however, more work is needed to test the robustness of this assertion. More importantly, the methodology is extensible to an entire fault system (thereby including multifault ruptures) and can be used to quantify the relative benefits of collecting additional paleoseismic data at different sites.

  3. Quaternary landscape development, alluvial fan chronology and erosion of the Mecca Hills at the southern end of the San Andreas Fault zone (United States)

    Gray, Harrison J.; Owen, Lewis; Dietsch, Craig; Beck, Richard A.; Caffee, Marc A.; Finkelman, Robert B.; Mahan, Shannon


    Quantitative geomorphic analysis combined with cosmogenic nuclide 10Be-based geochronology and denudation rates have been used to further the understanding of the Quaternary landscape development of the Mecca Hills, a zone of transpressional uplift along the southern end of the San Andreas Fault, in southern California. The similar timing of convergent uplifts along the San Andreas Fault with the initiation of the sub-parallel San Jacinto Fault suggest a possible link between the two tectonic events. The ages of alluvial fans and the rates of catchment-wide denudation have been integrated to assess the relative influence of climate and tectonic uplift on the development of catchments within the Mecca Hills. Ages for major geomorphic surfaces based on 10Be surface exposure dating of boulders and 10Be depth profiles define the timing of surface stabilization to 2.6 +5.6/–1.3 ka (Qyf1 surface), 67.2 ± 5.3 ka (Qvof2 surface), and 280 ± 24 ka (Qvof1 surface). Comparison of 10Be measurements from active channel deposits (Qac) and fluvial terraces (Qt) illustrate a complex history of erosion, sediment storage, and sediment transport in this environment. Beryllium-10 catchment-wide denudation rates range from 19.9 ± 3.2 to 149 ± 22.5 m/Ma and demonstrate strong correlations with mean catchment slope and with total active fault length normalized by catchment area. The lack of strong correlation with other geomorphic variables suggests that tectonic uplift and rock weakening have the greatest control. The currently measured topography and denudation rates across the Mecca Hills may be most consistent with a model of radial topographic growth in contrast to a model based on the rapid uplift and advection of crust.

  4. A New Estimate for Total Offset on the Southern San Andreas Fault: Implications for Cumulative Plate Boundary Shear in the Northern Gulf of California (United States)

    Darin, M. H.; Dorsey, R. J.


    Development of a consistent and balanced tectonic reconstruction for the late Cenozoic San Andreas fault (SAF) in southern California has been hindered for decades by incompatible estimates of total dextral offset based on different geologic cross-fault markers. The older estimate of 240-270 km is based on offset fluvial conglomerates of the middle Miocene Mint Canyon and Caliente Formations west of the SAF from their presumed source area in the northern Chocolate Mountains NE of the SAF (Ehlig et al., 1975; Ehlert, 2003). The second widely cited offset marker is a distinctive Triassic megaporphyritic monzogranite that has been offset 160 ± 10 km between Liebre Mountain west of the SAF and the San Bernadino Mountains (Matti and Morton, 1993). In this analysis we use existing paleocurrent data and late Miocene clockwise rotation in the eastern Transverse Ranges (ETR) to re-assess the orientation of the piercing line used in the 240 km-correlation, and present a palinspastic reconstruction that satisfies all existing geologic constraints. Our reconstruction of the Mint Canyon piercing line reduces the original estimate of 240-270 km to 195 ± 15 km of cumulative right-lateral slip on the southern SAF (sensu stricto), which is consistent with other published estimates of 185 ± 20 km based on correlative basement terranes in the Salton Trough region. Our estimate of ~195 km is consistent with the lower estimate of ~160 km on the Mojave segment because transform-parallel extension along the southwestern boundary of the ETR during transrotation produces ~25-40 km of displacement that does not affect offset markers of the Liebre/San Bernadino correlation located northwest of the ETR rotating domain. Reconciliation of these disparate estimates places an important new constraint on the total plate boundary shear that is likely accommodated in the adjacent northern Gulf of California. Global plate circuit models require ~650 km of cumulative Pacific-North America (PAC

  5. Fault tolerant control for uncertain systems with parametric faults

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Poulsen, Niels Kjølstad


    A fault tolerant control (FTC) architecture based on active fault diagnosis (AFD) and the YJBK (Youla, Jarb, Bongiorno and Kucera)parameterization is applied in this paper. Based on the FTC architecture, fault tolerant control of uncertain systems with slowly varying parametric faults...

  6. Andrea Cambini

    DEFF Research Database (Denmark)

    Lausten, Pia Schwarz


    Andrea Cambinis biografi (1445-1527) samt beskrivelse og analyse af værket 'Della origine de’ Turchi et imperio delli Ottomanni' (1529).......Andrea Cambinis biografi (1445-1527) samt beskrivelse og analyse af værket 'Della origine de’ Turchi et imperio delli Ottomanni' (1529)....

  7. Paleoseismic event dating and the conditional probability of large earthquakes on the southern San Andreas fault, California (United States)

    Biasi, G.P.; Weldon, R.J.; Fumal, T.E.; Seitz, G.G.


    We introduce a quantitative approach to paleoearthquake dating and apply it to paleoseismic data from the Wrightwood and Pallett Creek sites on the southern San Andreas fault. We illustrate how stratigraphic ordering, sedimentological, and historical data can be used quantitatively in the process of estimating earthquake ages. Calibrated radiocarbon age distributions are used directly from layer dating through recurrence intervals and recurrence probability estimation. The method does not eliminate subjective judgements in event dating, but it does provide a means of systematically and objectively approaching the dating process. Date distributions for the most recent 14 events at Wrightwood are based on sample and contextual evidence in Fumal et al. (2002) and site context and slip history in Weldon et al. (2002). Pallett Creek event and dating descriptions are from published sources. For the five most recent events at Wrightwood, our results are consistent with previously published estimates, with generally comparable or narrower uncertainties. For Pallett Creek, our earthquake date estimates generally overlap with previous results but typically have broader uncertainties. Some event date estimates are very sensitive to details of data interpretation. The historical earthquake in 1857 ruptured the ground at both sites but is not constrained by radiocarbon data. Radiocarbon ages, peat accumulation rates, and historical constraints at Pallett Creek for event X yield a date estimate in the earliest 1800s and preclude a date in the late 1600s. This event is almost certainly the historical 1812 earthquake, as previously concluded by Sieh et al. (1989). This earthquake also produced ground deformation at Wrightwood. All events at Pallett Creek, except for event T, about A.D. 1360, and possibly event I, about A.D. 960, have corresponding events at Wrightwood with some overlap in age ranges. Event T falls during a period of low sedimentation at Wrightwood when conditions

  8. Global Positioning System constraints on fault slip rates in southern California and northern Baja, Mexico (United States)

    Bennett, Richard A.; Rodi, William; Reilinger, Robert E.


    We use Global Positioning System (GPS) estimates of horizontal site velocity to constrain slip rates on faults comprising the Pacific-North America plate boundary in southern California and northern Mexico. We enlist a simple elastic block model to parameterize the distribution and sum of deformation within and across the plate boundary. We estimate a Pacific-North America relative plate motion rate of 49 ± 3 mm/yr (one standard deviation), consistent with NUVEL-1A estimates. We are able to resolve robust slip rate estimates for the southernmost San Andreas, San Jacinto, and Elsinore faults (26 ± 2, 9 ± 2, and 6 ± 2 mm/yr, respectively) and for the Imperial and Cerro Prieto faults (35 ± 2 and 42 ± 1 mm/yr, respectively), accounting for about 86% of the total plate motion. The remaining 14% appears to be accommodated to the west of these fault systems, probably via slip along the San Clemente fault and/or the San Miguel, Vallecitos, Rose Canyon, and Newport-Inglewood fault systems. These results are highly consistent with paleoseismic estimates for slip rates implying that off-fault strain accumulation within the deforming zone of the plate boundary is largely elastic. We estimate that the seismically quiescent, southernmost San Andreas fault has incurred about 8.2 m of slip deficit over the last few hundred years, presumably to be recovered during a future large earthquake.

  9. Characterization of a Strain Rate Transient Along the San Andreas and San Jacinto Faults Following the October 1999 Hector Mine Earthquake. (United States)

    Hernandez, D.; Holt, W. E.; Bennett, R. A.; Dimitrova, L.; Haines, A. J.


    We are continuing work on developing and refining a tool for recognizing strain rate transients as well as for quantifying the magnitude and style of their temporal and spatial variations. We determined time-averaged velocity values in 0.05 year epochs using time-varying velocity estimates for continuous GPS station data from the Southern California Integrated GPS Network (SCIGN) for the time period between October 1999 and February 2004 [Li et al., 2005]. A self-consistent model velocity gradient tensor field solution is determined for each epoch by fitting bi-cubic Bessel interpolation to the GPS velocity vectors and we determine model dilatation strain rates, shear strain rates, and the rotation rates. Departures of the time dependent model strain rate and velocity fields from a master solution, obtained from a time-averaged solution for the period 1999-2004, with imposed plate motion constraints and Quaternary fault data, are evaluated in order to best characterize the time dependent strain rate field. A particular problem in determining the transient strain rate fields is the level of smoothing or damping that is applied. Our current approach is to choose a damping that both maximizes the departure of the transient strain rate field from the long-term master solution and achieves a reduced chi-squared value between model and observed GPS velocities of around 1.0 for all time epochs. We observe several noteworthy time-dependent changes. First, in the Eastern California Shear Zone (ECSZ) region, immediately following the October 1999 Hector Mine earthquake, there occurs a significant spatial increase of relatively high shear strain rate, which encompasses a significant portion of the ECSZ. Second, also following the Hector Mine event, there is a strain rate corridor that extends through the Pinto Mt. fault connecting the ECSZ to the San Andreas fault segment in the Salton Trough region. As this signal slowly decays, shear strain rates on segments of the San

  10. Sierran affinity (?) metasedimentary rocks beneath the Coast Range Ophiolite of the Sierra Azul block east of the San Andreas fault, Santa Clara County, CA (United States)

    McLaughlin, R. J.; Dumitru, T. A.; Ernst, W. G.


    The Loma Prieta slate (LPS) is a 200 Ma are generally similar in the LPS and MFS, with minor age groupings at roughly 950-1450 and 1750-2100 Ma. As with the MFS, the LPS data suggest a major influence from sources in the Sierra Nevada arc, with minimal influences from sources in the Klamath Mountains and Nevada miogeocline. Available detrital zircon data require Cretaceous or younger maximum depositional ages for metaclastic terranes of the Franciscan Complex. The LPS detrital zircon data thus, are in reasonable agreement with the MFS data and permit interpretation of the LPS as displaced northward by the San Andreas and Hayward-Calaveras faults from the southwestern Great Valley margin.

  11. Fractal properties and simulation of micro-seismicity for seismic hazard analysis: a comparison of North Anatolian and San Andreas Fault Zones

    Directory of Open Access Journals (Sweden)

    Naside Ozer


    Full Text Available We analyzed statistical properties of earthquakes in western Anatolia as well as the North Anatolian Fault Zone (NAFZ in terms of spatio-temporal variations of fractal dimensions, p- and b-values. During statistically homogeneous periods characterized by closer fractal dimension values, we propose that occurrence of relatively larger shocks (M >= 5.0 is unlikely. Decreases in seismic activity in such intervals result in spatial b-value distributions that are primarily stable. Fractal dimensions decrease with time in proportion to increasing seismicity. Conversely, no spatiotemporal patterns were observed for p-value changes. In order to evaluate failure probabilities and simulate earthquake occurrence in the western NAFZ, we applied a modified version of the renormalization group method. Assuming an increase in small earthquakes is indicative of larger shocks, we apply the mentioned model to micro-seismic (M<= 3.0 activity, and test our results using San Andreas Fault Zone (SAFZ data. We propose that fractal dimension is a direct indicator of material heterogeneity and strength. Results from a model suggest simulated and observed earthquake occurrences are coherent, and may be used for seismic hazard estimation on creeping strike-slip fault zones.

  12. Evaluating the relationship between lateral slip and repeated fold deformation along a transtensive step-over on the San Andreas fault at the Frazier Mountain site (United States)

    Weldon, R. J.; Streig, A. R.; Frazier Mountain SoSAFE Trenching Team


    Transtensive step-overs known as sags are among the most ubiquitous features of strike slip faults. These structures create closed depressions that collect sediment, are often wet and thus preserve organic material that can be used to date the thick and rapidly accumulating section. It is clear from historical ruptures that these depressions grow incrementally with each earthquake. We are developing methods to carefully document and separate individual folding events, and to relate the amount of sagging or folding to the amount of horizontal slip creating the sag, with the goal of generating slip per event chronologies. This will be useful as sags are often the best sites for preserving evidence of earthquake timing, and determining slip at these sites will eliminate the ambiguity inherent in tying earthquake age data from micro-stratigraphic sites to nearby undated sites with good micro-geomorphic slip evidence. We apply this approach to the Frazier Mountain site on the Southern San Andreas fault where we integrate trenching, cone penetrometer testing (CPT), surveying, photomosaicing, B4 LiDAR data and GIS techniques to make a detailed 3D map of subsurface geology, fault traces and related folds across the site. These data are used to generate structure contour and isopach maps for key stratigraphic units in order to evaluate fold deformation of paleo-ground surfaces across a transtensional step-over on the San Andreas fault. Approximately 20 trenches show the main active trace of the San Andreas fault right stepping ~30 m over ~100 m along strike producing two small synclinal sags that dramatically thicken the stratigraphic section. The northwest sag is about 50 m long, 5 m wide, and the southwest sag measures 20 m long and about 8 m wide. The Frazier Mountain site has yielded good earthquake chronologies, and relationships between fold deformation and surface fault rupture for the last 6 earthquakes. We observe that the degree of sagging in the synclines varies

  13. Late Quaternary slip history of the Mill Creek strand of the San Andreas fault in San Gorgonio Pass, southern California: The role of a subsidiary left-lateral fault in strand switching (United States)

    Kendrick, Katherine J.; Matti, Jonathan; Mahan, Shannon


    The fault history of the Mill Creek strand of the San Andreas fault (SAF) in the San Gorgonio Pass region, along with the reconstructed geomorphology surrounding this fault strand, reveals the important role of the left-lateral Pinto Mountain fault in the regional fault strand switching. The Mill Creek strand has 7.1–8.7 km total slip. Following this displacement, the Pinto Mountain fault offset the Mill Creek strand 1–1.25 km, as SAF slip transferred to the San Bernardino, Banning, and Garnet Hill strands. An alluvial complex within the Mission Creek watershed can be linked to palinspastic reconstruction of drainage segments to constrain slip history of the Mill Creek strand. We investigated surface remnants through detailed geologic mapping, morphometric and stratigraphic analysis, geochronology, and pedogenic analysis. The degree of soil development constrains the duration of surface stability when correlated to other regional, independently dated pedons. This correlation indicates that the oldest surfaces are significantly older than 500 ka. Luminescence dates of 106 ka and 95 ka from (respectively) 5 and 4 m beneath a younger fan surface are consistent with age estimates based on soil-profile development. Offset of the Mill Creek strand by the Pinto Mountain fault suggests a short-term slip rate of ∼10–12.5 mm/yr for the Pinto Mountain fault, and a lower long-term slip rate. Uplift of the Yucaipa Ridge block during the period of Mill Creek strand activity is consistent with thermochronologic modeled uplift estimates.

  14. Row fault detection system (United States)

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


    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.

  15. Fault tolerant control for switched linear systems

    CERN Document Server

    Du, Dongsheng; Shi, Peng


    This book presents up-to-date research and novel methodologies on fault diagnosis and fault tolerant control for switched linear systems. It provides a unified yet neat framework of filtering, fault detection, fault diagnosis and fault tolerant control of switched systems. It can therefore serve as a useful textbook for senior and/or graduate students who are interested in knowing the state-of-the-art of filtering, fault detection, fault diagnosis and fault tolerant control areas, as well as recent advances in switched linear systems.  

  16. S-wave triggering of tremor beneath the Parkfield, California, section of the San Andreas fault by the 2011 Tohoku, Japan earthquake: observations and theory (United States)

    Hill, David P.; Peng, Zhigang; Shelly, David R.; Aiken, Chastity


    The dynamic stresses that are associated with the energetic seismic waves generated by the Mw 9.0 Tohoku earthquake off the northeast coast of Japan triggered bursts of tectonic tremor beneath the Parkfield section of the San Andreas fault (SAF) at an epicentral distance of ∼8200  km. The onset of tremor begins midway through the ∼100‐s‐period S‐wave arrival, with a minor burst coinciding with the SHSH arrival, as recorded on the nearby broadband seismic station PKD. A more pronounced burst coincides with the Love arrival, followed by a series of impulsive tremor bursts apparently modulated by the 20‐ to 30‐s‐period Rayleigh wave. The triggered tremor was located at depths between 20 and 30 km beneath the surface trace of the fault, with the burst coincident with the S wave centered beneath the fault 30 km northwest of Parkfield. Most of the subsequent activity, including the tremor coincident with the SHSH arrival, was concentrated beneath a stretch of the fault extending from 10 to 40 km southeast of Parkfield. The seismic waves from the Tohoku epicenter form a horizontal incidence angle of ∼14°, with respect to the local strike of the SAF. Computed peak dynamic Coulomb stresses on the fault at tremor depths are in the 0.7–10 kPa range. The apparent modulation of tremor bursts by the small, strike‐parallel Rayleigh‐wave stresses (∼0.7  kPa) is likely enabled by pore pressure variations driven by the Rayleigh‐wave dilatational stress. These results are consistent with the strike‐parallel dynamic stresses (δτs) associated with the S, SHSH, and surface‐wave phases triggering small increments of dextral slip on the fault with a low friction (μ∼0.2). The vertical dynamic stresses δτd do not trigger tremor with vertical or oblique slip under this simple Coulomb failure model.

  17. Timing of Landform Displacements along the Mojave Section of the San Andreas Fault: A Comparison of Field-based and Remote Reconstructions at Two Sites (United States)

    Barr, M. A.; Cowgill, E.


    Determining the Holocene slip rate of the Mojave section of the San Andreas Fault (MSAF) is key for assessing the earthquake hazard that this ~150-km-long section of fault poses to the Los Angeles metropolitan area, which is located ~45 km to the southwest. Possible temporal variations in slip rate along the MSAF are suggested by an apparent discrepancy between geologically and geodetically determined slip rates, with rates from geologic observations reported to be up to twice as fast as those reported from geodetic data. This apparent variability could be the result of changes in slip rate over time, which is known as secular variation in slip. To test the hypothesis that the MSAF exhibits variability in slip rate over time requires establishing not just a Holocene-average slip rate, but a Holocene slip history. Previous work along the MSAF using remote, virtual-reality based analysis of B4 LiDAR topographic data and pilot field observations identified ~60 potential slip-rate sites with landform offsets between 30 and 300 m, 10 of which are particularly promising. We are currently conducting detailed, field-based studies at two of these 10 sites (Oakdale and Shoemaker Canyon), with an emphasis on collecting age and offset data to determine both Holocene-average slip rates and constrain slip-history analysis. Initial offset estimates were made by remote analysis using 3D visualization software with 1-meter resolution LiDAR (Light Detection and Ranging) data. We plan to excavate exploratory, fault-parallel trenches both northwest and southeast of the fault to constrain the ages of offset landforms, correlate depositional events across the fault, and test the offset estimates that were determined remotely. Upon establishing the stratigraphic relationships of lithologic units within the trenches and correlating this stratigraphy across the fault, we plan to employ geochronologic techniques to quantify the age of depositional events. The nature of the deposits will

  18. Fault Detection for Nonlinear Systems

    DEFF Research Database (Denmark)

    Stoustrup, Jakob; Niemann, H.H.


    The paper describes a general method for designing fault detection and isolation (FDI) systems for nonlinear processes. For a rich class of nonlinear systems, a nonlinear FDI system can be designed using convex optimization procedures. The proposed method is a natural extension of methods based...

  19. Timing of large earthquakes during the past 500 years along the Santa Cruz Mountains segment of the San Andreas fault at Mill Canyon, near Watsonville, California (United States)

    Fumal, Thomas E.


    A paleoseismic investigation across the Santa Cruz Mountains section of the San Andreas fault at Mill Canyon indicates that four surface‐rupturing earthquakes have occurred there during the past ~500  years. At this site, right‐lateral fault slip has moved a low shutter ridge across the mouth of the canyon, ponding latest Holocene sediments. These alluvial deposits are deformed along a narrow zone of faulting. There is excellent evidence for a 1906 (M 7.8) and three earlier earthquakes consisting of well‐developed fissures, scarps, and colluvial wedges. Deformation resulting from the earlier earthquakes is comparable to that from 1906, suggesting they also were large‐magnitude events. The earthquake prior to 1906 occurred either about A.D. 1750 (1711–1770) or A.D. 1855 (1789–1904), depending on assumptions incorporated into two alternative OxCal models. If the later age range is correct, then the earthquake may have been a historical early‐to‐mid‐nineteenth‐century earthquake, possibly the A.D. 1838 earthquake. Both models are viable, and there is no way to select one over the other with the available data. Two earlier earthquakes occurred about A.D. 1690 (1660–1720) and A.D. 1522 (1454–1605). Using OxCal, recalculation of the age of the reported penultimate earthquake reported from the Grizzly Flat site, located about 10 km northwest of Mill Canyon, indicates it occurred about A.D. 1105–1545, earlier than any of the past three earthquakes, and possibly correlates to the fourth earthquake at Mill Canyon.

  20. Coefficient of Variation Estimates for the Plate Boundary Fault System of California (United States)

    Biasi, G. P.; Scharer, K. M.


    The number of high-quality paleoseismic records on major strike-slip faults of California has increased in recent years to the point that patterns in earthquake recurrence are emerging. The degree of predictability in time intervals between ground-rupturing earthquakes can be measured by the CoV (coefficient of variation). The CoV approximately normalizes for mean recurrence, and is thus useful to isolate the temporal variability of earthquake records. CoV estimates are themselves uncertain because input dates are actually probability distributions and because paleoseismic records are short and not necessarily representative samples from the underlying recurrence distribution. Radiocarbon dating uncertainty can be incorporated by sampling from event PDFs and compiling sample CoV estimates. Uncertainty due to the brevity of the site event record is larger, and neglect of it can lead to improbable estimates. Long records are now available on the San Andreas and San Jacinto faults in Southern California, and the San Andreas and Hayward faults in northern California. These faults accommodate most of the Pacific-North American relative plate motion in their respective regions. CoV estimates from sites with 8 or more events cluster around 0.63, but are as low as 0.4 for the southern Hayward fault. Sites with fewer events give similar estimates, though with lower resolution. The one prominent outlier, Burro Flats, with a CoV near 1.0, is in a region of severe fault complexity and rapid fault-normal compression. Quasi-periodic recurrence is emerging as a general property for these plate boundary faults. Some individual site records allow that, at low probabilities, recurrence could be random in time. When the ensemble is considered together, however, it is improbable that we would see the observed degree of agreement among boundary fault paleoseismic records; the more likely explanation is that quasi-periodic recurrence is a real property of the boundary fault system.

  1. Evidence for 115 kilometers of right slip on the san gregorio-hosgri fault trend. (United States)

    Graham, S A; Dickinson, W R


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

  2. Transient Faults in Computer Systems (United States)

    Masson, Gerald M.


    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.

  3. Architecting fault-tolerant software systems

    NARCIS (Netherlands)

    Sözer, Hasan


    The increasing size and complexity of software systems makes it hard to prevent or remove all possible faults. Faults that remain in the system can eventually lead to a system failure. Fault tolerance techniques are introduced for enabling systems to recover and continue operation when they are subj

  4. Large-scale right-slip displacement on the East San Francisco Bay Region fault system, California: Implications for location of late Miocene to Pliocene Pacific plate boundary (United States)

    McLaughlin, R.J.; Sliter, W.V.; Sorg, D.H.; Russell, P.C.; Sarna-Wojcicki, A. M.


    A belt of northwardly younging Neogene and Quaternary volcanic rocks and hydrothermal vein systems, together with a distinctive Cretaceous terrane of the Franciscan Complex (the Permanente terrane), exhibits about 160 to 170 km of cumulative dextral offset across faults of the East San Francisco Bay Region (ESFBR) fault system. The offset hydrothermal veins and volcanic rocks range in age from .01 Ma at the northwest end to about 17.6 Ma at the southeast end. In the fault block between the San Andreas and ESFBR fault systems, where volcanic rocks are scarce, hydrothermal vein system ages clearly indicate that the northward younging thermal overprint affected these rocks beginning about 18 Ma. The age progression of these volcanic rocks and hydrothermal vein systems is consistent with previously proposed models that relate northward propagation of the San Andreas transform to the opening of an asthenospheric window beneath the North American plate margin in the wake of subducting lithosphere. The similarity in the amount of offset of the Permanente terrane across the ESFBR fault system to that derived by restoring continuity in the northward younging age progression of volcanic rocks and hydrothermal veins suggests a model in which 80-110 km of offset are taken up 8 to 6 Ma on a fault aligned with the Bloomfield-Tolay-Franklin-Concord-Sunol-Calaveras faults. An additional 50-70 km of cumulative slip are taken up ??? 6 Ma by the Rogers Creek-Hayward and Concord-Franklin-Sunol-Calaveras faults. An alternative model in which the Permanente terrane is offset about 80 km by pre-Miocene faults does not adequately restore the distribution of 8-12 Ma volcanic rocks and hydrothermal veins to a single northwardly younging age trend. If 80-110 km of slip was taken up by the ESFBR fault system between 8 and 6 Ma, dextral slip rates were 40-55 mm/yr. Such high rates might occur if the ESFBR fault system rather than the San Andreas fault acted as the transform margin at this time

  5. Synthesis of Fault-Tolerant Embedded Systems

    DEFF Research Database (Denmark)

    Eles, Petru; Izosimov, Viacheslav; Pop, Paul


    This work addresses the issue of design optimization for fault- tolerant hard real-time systems. In particular, our focus is on the handling of transient faults using both checkpointing with rollback recovery and active replication. Fault tolerant schedules are generated based on a conditional pr...

  6. Active fault detection in MIMO systems

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Poulsen, Niels Kjølstad


    The focus in this paper is on active fault detection (AFD) for MIMO systems with parametric faults. The problem of design of auxiliary inputs with respect to detection of parametric faults is investigated. An analysis of the design of auxiliary inputs is given based on analytic transfer functions...

  7. Scientific Visualizations of Data Collected From EarthScope's Seismic Observatory (USArray) and San Andreas Fault Observatory at Depth (SAFOD) (United States)

    Kilb, D.; Im, T.; Quan, A.; Nayak, A.; Weiland, C.; Kent, G.


    Looking at data from perspectives other than map view, or standard cross sections, can help researchers with their science. Interactively exploring visualizations of multi-dimensional data allows scientists to assess the quality of their data, identify links between different data types, assist with project planning, refine their hypotheses and more easily convey research findings to a wide range of audiences. Working with EarthScope scientists we explore ways to use visualization techniques to help researchers explore their data and explain key concepts and theories. Examples of our visualizations include: (1) Movies of the temporal evolution of earthquakes, detected and recorded by USArray stations, juxtaposed with the progress of USArray station deployment. (2) Using the USArray station spacing as an irregular grid we create a 3D mesh depicting displacements generated by teleseismic waves. (3) An interactive 3D visualization of data pertaining to the SAFOD observatory (i.e., drill hole plans, side tracks, surface and borehole experiment locations, geologic cross-sections, seismicity and fault planes). (4) Exploration of the temporal evolution of the Rayleigh wave group velocity dispersion throughout the California region. (5) Interactive 3D visualizations of notable earthquakes that include, but are not limited to, the location of the mainshock epicenter and hypocenter, historical seismicity, USArray seismic station locations and station codes, geographic boundaries and topography of the region. We make these visualizations available for free download on the web within a day or two of the mainshock event so they can be used in classrooms, outreach venues and for media response. These visualizations can be accessed from the visual objects library at the Scripps Institution of Oceanography's Visualization Center ( They include 3D interactive visualizations, Quicktime movies and online tools and can be explored using

  8. Fault tolerant control design for hybrid systems

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Hao; Jiang, Bin [Nanjing University of Aeronautics and Astronautics, Nanjing (China); Cocquempot, Vincent [Universite des Sciences et Technologies de Lille, Villeneuve d' Ascq (France)


    This book intends to provide the readers a good understanding on how to achieve Fault Tolerant Control goal of Hybrid Systems. The book can be used as a reference for the academic research on Fault Tolerant Control and Hybrid Systems or used in Ph.D. study of control theory and engineering. The knowledge background for this monograph would be some undergraduate and graduate courses on Fault Diagnosis and Fault Tolerant Control theory, linear system theory, nonlinear system theory, Hybrid Systems theory and Discrete Event System theory. (orig.)

  9. Rock Properties and Internal Structure of the San Andreas Fault near ~ 3 km Depth in the SAFOD Borehole Based on Meso- to Micro-scale Analyses of Phase III whole rock core (United States)

    Bradbury, K.; Evans, J. P.


    We examine the relationships between rock properties and structure within ~ 41 m of PHASE III whole-rock core collected from ~ 3 km depth along the SAF in the San Andreas Fault Observatory at Depth (SAFOD) borehole, near Parkfield, CA. Direct mesoscale observations of the core are integrated with detailed petrography and microstructural analyses coupled with X-Ray Diffraction and X-Ray Fluorescence techniques to document variations in composition, alteration, and structures that may be related to deformation and/or fluid-rock interactions. Across the low velocity zone (LVZ) defined by borehole geophysical data, lithologies are comprised of a heterogeneous sequence of fine-grained sandstones, siltstones, mudstones, and shales with block-in-matrix textures and pervasively foliated fabrics. More competent clasts within the block-in-matrix materials exhibit pinch-and-swell shaped structures with crosscutting veins that do not extend into the surrounding phyllosilicate-rich matrix. Narrow fault strands at 3192 and 3302 m bound the LVZ and correspond to sites of active casing deformation (aseismic creep). Here, the rock consists of ~ 2 m thick serpentinite-bearing phyllosilicate gouge with a pervasive penetrative scaly clay fabric and phacoidal-shaped clasts. Bounding these two active slip surfaces are highly sheared and comminuted ultrafine-grained black fault rocks with abundant calcite veins parallel and oblique to the foliation trend. Localized shear surfaces bound multi-layered zones of medium to ultra-fine grained cataclasite in the near-fault environment and record multiple generations of brittle deformation processes. Deformation at high-strain rates is suggested by the presence of crack-seal veins in clasts within the block-in-matrix materials, the presence of porphyroclasts, and the development of S-C fabrics in the phyllosilicate-rich gouge. Across the fault(s) and related damage zones, foliated fabrics alternating with discrete fractures suggest a mixed

  10. From fault classification to fault tolerance for multi-agent systems

    CERN Document Server

    Potiron, Katia; Taillibert, Patrick


    Faults are a concern for Multi-Agent Systems (MAS) designers, especially if the MAS are built for industrial or military use because there must be some guarantee of dependability. Some fault classification exists for classical systems, and is used to define faults. When dependability is at stake, such fault classification may be used from the beginning of the system's conception to define fault classes and specify which types of faults are expected. Thus, one may want to use fault classification for MAS; however, From Fault Classification to Fault Tolerance for Multi-Agent Systems argues that

  11. Fuzzy fault diagnosis system of MCFC

    Institute of Scientific and Technical Information of China (English)

    Wang Zhenlei; Qian Feng; Cao Guangyi


    A kind of fault diagnosis system of molten carbonate fuel cell (MCFC) stack is proposed in this paper. It is composed of a fuzzy neural network (FNN) and a fault diagnosis element. FNN is able to deal with the information of the expert knowledge and the experiment data efficiently. It also has the ability to approximate any smooth system. FNN is used to identify the fault diagnosis model of MCFC stack. The fuzzy fault decision element can diagnose the state of the MCFC generating system, normal or fault, and can decide the type of the fault based on the outputs of FNN model and the MCFC system. Some simulation experiment results are demonstrated in this paper.

  12. Arc burst pattern analysis fault detection system (United States)

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


    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. Fault system polarity: A matter of chance? (United States)

    Schöpfer, Martin; Childs, Conrad; Manzocchi, Tom; Walsh, John; Nicol, Andy; Grasemann, Bernhard


    Many normal fault systems and, on a smaller scale, fracture boudinage exhibit asymmetry so that one fault dip direction dominates. The fraction of throw (or heave) accommodated by faults with the same dip direction in relation to the total fault system throw (or heave) is a quantitative measure of fault system asymmetry and termed 'polarity'. It is a common belief that the formation of domino and shear band boudinage with a monoclinic symmetry requires a component of layer parallel shearing, whereas torn boudins reflect coaxial flow. Moreover, domains of parallel faults are frequently used to infer the presence of a common décollement. Here we show, using Distinct Element Method (DEM) models in which rock is represented by an assemblage of bonded circular particles, that asymmetric fault systems can emerge under symmetric boundary conditions. The pre-requisite for the development of domains of parallel faults is however that the medium surrounding the brittle layer has a very low strength. We demonstrate that, if the 'competence' contrast between the brittle layer and the surrounding material ('jacket', or 'matrix') is high, the fault dip directions and hence fault system polarity can be explained using a random process. The results imply that domains of parallel faults are, for the conditions and properties used in our models, in fact a matter of chance. Our models suggest that domino and shear band boudinage can be an unreliable shear-sense indicator. Moreover, the presence of a décollement should not be inferred on the basis of a domain of parallel faults only.

  14. Explaining the current geodetic field with geological models: A case study of the Haiyuan fault system (United States)

    Daout, S.; Jolivet, R.; Lasserre, C.; Doin, M. P.; Barbot, S.; Peltzer, G.; Tapponnier, P.


    Oblique convergence across Tibet leads to slip partitioning with the co-existence of strike-slip, normal and thrust motion in major fault systems. While such complexity has been shown at the surface, the question is to understand how faults interact and accumulate strain at depth. Here, we process InSAR data across the central Haiyuan restraining bend, at the north-eastern boundary of the Tibetan plateau and show that the surface complexity can be explained by partitioning of a uniform deep-seated convergence rate. We construct a time series of ground deformation, from Envisat radar data spanning from 2001-2011 period, across a challenging area because of the high jump in topography between the desert environment and the plateau. To improve the signal-to-noise ratio, we used the latest Synthetic Aperture Radar interferometry methodology, such as Global Atmospheric Models (ERA Interim) and Digital Elevation Model errors corrections before unwrapping. We then developed a new Bayesian approach, jointly inverting our InSAR time series together with published GPS displacements. We explore fault system geometry at depth and associated slip rates and determine a uniform N86±7E° convergence rate of 8.45±1.4 mm/yr across the whole fault system with a variable partitioning west and east of a major extensional fault-jog. Our 2D model gives a quantitative understanding of how crustal deformation is accumulated by the various branches of this thrust/strike-slip fault system and demonstrate the importance of the geometry of the Haiyuan Fault, controlling the partitioning or the extrusion of the block motion. The approach we have developed would allow constraining the low strain accumulation along deep faults, like for example for the blind thrust faults or possible detachment in the San Andreas "big bend", which are often associated to a poorly understood seismic hazard.

  15. Software fault tolerance in computer operating systems (United States)

    Iyer, Ravishankar K.; Lee, Inhwan


    This chapter provides data and analysis of the dependability and fault tolerance for three operating systems: the Tandem/GUARDIAN fault-tolerant system, the VAX/VMS distributed system, and the IBM/MVS system. Based on measurements from these systems, basic software error characteristics are investigated. Fault tolerance in operating systems resulting from the use of process pairs and recovery routines is evaluated. Two levels of models are developed to analyze error and recovery processes inside an operating system and interactions among multiple instances of an operating system running in a distributed environment. The measurements show that the use of process pairs in Tandem systems, which was originally intended for tolerating hardware faults, allows the system to tolerate about 70% of defects in system software that result in processor failures. The loose coupling between processors which results in the backup execution (the processor state and the sequence of events occurring) being different from the original execution is a major reason for the measured software fault tolerance. The IBM/MVS system fault tolerance almost doubles when recovery routines are provided, in comparison to the case in which no recovery routines are available. However, even when recovery routines are provided, there is almost a 50% chance of system failure when critical system jobs are involved.

  16. Cell boundary fault detection system (United States)

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


    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.

  17. Fault isolability conditions for linear systems with additive faults

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Stoustrup, Jakob


    In this paper, we shall show that an unlimited number of additive single faults can be isolated under mild conditions if a general isolation scheme is applied. Multiple faults are also covered. The approach is algebraic and is based on a set representation of faults, where all faults within a set...

  18. Fault detection and fault-tolerant control for nonlinear systems

    CERN Document Server

    Li, Linlin


    Linlin Li addresses the analysis and design issues of observer-based FD and FTC for nonlinear systems. The author analyses the existence conditions for the nonlinear observer-based FD systems to gain a deeper insight into the construction of FD systems. Aided by the T-S fuzzy technique, she recommends different design schemes, among them the L_inf/L_2 type of FD systems. The derived FD and FTC approaches are verified by two benchmark processes. Contents Overview of FD and FTC Technology Configuration of Nonlinear Observer-Based FD Systems Design of L2 nonlinear Observer-Based FD Systems Design of Weighted Fuzzy Observer-Based FD Systems FTC Configurations for Nonlinear Systems< Application to Benchmark Processes Target Groups Researchers and students in the field of engineering with a focus on fault diagnosis and fault-tolerant control fields The Author Dr. Linlin Li completed her dissertation under the supervision of Prof. Steven X. Ding at the Faculty of Engineering, University of Duisburg-Essen, Germany...

  19. Energy-efficient fault-tolerant systems

    CERN Document Server

    Mathew, Jimson; Pradhan, Dhiraj K


    This book describes the state-of-the-art in energy efficient, fault-tolerant embedded systems. It covers the entire product lifecycle of electronic systems design, analysis and testing and includes discussion of both circuit and system-level approaches. Readers will be enabled to meet the conflicting design objectives of energy efficiency and fault-tolerance for reliability, given the up-to-date techniques presented.

  20. Extreme multi-millennial slip rate variations on the Garlock fault, California: Strain super-cycles, potentially time-variable fault strength, and implications for system-level earthquake occurrence (United States)

    Dolan, James F.; McAuliffe, Lee J.; Rhodes, Edward J.; McGill, Sally F.; Zinke, Robert


    Pronounced variations in fault slip rate revealed by new measurements along the Garlock fault have basic implications for understanding how faults store and release strain energy in large earthquakes. Specifically, dating of a series of 26.0+3.5/-2.5 m fault offsets with a newly developed infrared-stimulated luminescence method shows that the fault was slipping at >14.0+2.2/-1.8 mm /yr, approximately twice as fast as the long-term average rate, during a previously documented cluster of four earthquakes 0.5-2.0 ka. This elevated late Holocene rate must be balanced by periods of slow or no slip such as that during the ca. 3300-yr-long seismic lull preceding the cluster. Moreover, whereas a comparison of paleoseismic data and stress modeling results suggests that individual Garlock earthquakes may be triggered by periods of rapid San Andreas fault slip or very large-slip events, the ;on-off; behavior of the Garlock suggests a longer-term mechanism that may involve changes in the rate of elastic strain accumulation on the fault over millennial time scales. This inference is consistent with most models of the geodetic velocity field, which yield slip-deficit rates that are much slower than the average latest Pleistocene-early Holocene (post-8-13 ka) Garlock slip rate of 6.5 ± 1.5 mm /yr. These observations indicate the occurrence of millennia-long strain ;super-cycles; on the Garlock fault that may be associated with temporal changes in elastic strain accumulation rate, which may in turn be controlled by variations in relative strength of the various faults in the Garlock-San Andreas-Eastern California Shear Zone fault system and/or changes in relative plate motion rates.

  1. Faults and Diagnosis Systems in Power Converters

    DEFF Research Database (Denmark)

    Lee, Kyo-Beum; Choi, Uimin


    efforts have been put into making these systems better in terms of reliability in order to achieve high power source availability, reduce the cost of energy and also increase the reliability of overall systems. Among the components used in power converters, a power device and a capacitor fault occurs most......A power converter is needed in almost all kinds of renewable energy systems and drive systems. It is used both for controlling the renewable source and for interfacing with the load, which can be grid-connected or working in standalone mode. Further, it drives the motors efficiently. Increasing...... frequently. Therefore, it is important to monitor the power device and capacitor fault to increase the reliability of power electronics. In this chapter, the diagnosis methods for power device fault will be discussed by dividing into open- and short-circuit faults. Then, the condition monitoring methods...

  2. Robust Fault Diagnosis Design for Linear Multiagent Systems with Incipient Faults

    Directory of Open Access Journals (Sweden)

    Jingping Xia


    Full Text Available The design of a robust fault estimation observer is studied for linear multiagent systems subject to incipient faults. By considering the fact that incipient faults are in low-frequency domain, the fault estimation of such faults is proposed for discrete-time multiagent systems based on finite-frequency technique. Moreover, using the decomposition design, an equivalent conclusion is given. Simulation results of a numerical example are presented to demonstrate the effectiveness of the proposed techniques.

  3. Subtropical Storm Andrea (United States)


    The circling clouds of an intense low-pressure system sat off the southeast coast of the United States on May 8, 2007, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured this image. By the following morning, the storm developed enough to be classified as a subtropical storm, a storm that forms outside of the tropics, but has many of the characteristics--hurricane-force winds, driving rains, low pressure, and sometimes an eye--of a tropical storm. Although it arrived several weeks shy of the official start of the hurricane season (June 1), Subtropical Storm Andrea became the first named storm of the 2007 Atlantic hurricane season. The storm has the circular shape of a tropical cyclone in this image, but lacks the tight organization seen in more powerful storms. By May 9, the storm's winds reached 75 kilometers per hour (45 miles per hour), and the storm was not predicted to get any stronger, said the National Hurricane Center. Though Subtropical Storm Andrea was expected to remain offshore, its strong winds and high waves pummeled coastal states, prompting a tropical storm watch. The winds fueled wild fires (marked with red boxes) in Georgia and Florida. The wind-driven flames generated thick plumes of smoke that concentrated in a gray-brown mass over Tampa Bay, Florida. Unfortunately for Georgia and Florida, which are experiencing moderate to severe drought, Subtropical Storm Andrea was not predicted to bring significant rain to the region right away, according to reports on the Washington Post Website.

  4. H infinity Integrated Fault Estimation and Fault Tolerant Control of Discrete-time Piecewise Linear Systems

    DEFF Research Database (Denmark)

    Tabatabaeipour, Seyed Mojtaba; Bak, Thomas


    In this paper we consider the problem of fault estimation and accommodation for discrete time piecewise linear systems. A robust fault estimator is designed to estimate the fault such that the estimation error converges to zero and H∞ performance of the fault estimation is minimized. Then......, the estimate of fault is used to compensate for the effect of the fault. Hence, using the estimate of fault, a fault tolerant controller using a piecewise linear static output feedback is designed such that it stabilizes the system and provides an upper bound on the H∞ performance of the faulty system....... Sufficient conditions for the existence of robust fault estimator and fault tolerant controller are derived in terms of linear matrix inequalities. Upper bounds on the H∞ performance can be minimized by solving convex optimization problems with linear matrix inequality constraints. The efficiency...

  5. Guaranteed Cost Fault-Tolerant Control for Networked Control Systems with Sensor Faults


    Qixin Zhu; Kaihong Lu; Guangming Xie; Yonghong Zhu


    For the large scale and complicated structure of networked control systems, time-varying sensor faults could inevitably occur when the system works in a poor environment. Guaranteed cost fault-tolerant controller for the new networked control systems with time-varying sensor faults is designed in this paper. Based on time delay of the network transmission environment, the networked control systems with sensor faults are modeled as a discrete-time system with uncertain parameters. And the mode...

  6. Architecture of small-scale fault zones in the context of the Leinetalgraben Fault System (United States)

    Reyer, Dorothea; Philipp, Sonja L.


    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

  7. Active fault diagnosis in closed-loop uncertain systems

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik


    Fault diagnosis of parametric faults in closed-loop uncertain systems by using an auxiliary input vector is considered in this paper, i.e. active fault diagnosis (AFD). The active fault diagnosis is based directly on the socalled fault signature matrix, related to the YJBK (Youla, Jabr, Bongiorno...... and Kucera) parameterization. Conditions are given for exact detection and isolation of parametric faults in closed-loop uncertain systems....

  8. Regional Fault Systems of Qaidam Basin and Adjacent Orogenic Belts

    Institute of Scientific and Technical Information of China (English)


    The purpose of this paper is to analyze the regional fault systems of Qaidam basin and adjacent orogenic belts. Field investigation and seismic interpretation indicate that five regional fault systems occurred in the Qaidam and adjacent mountain belts, controlling the development and evolution of the Qaidam basin. These fault systems are: (1)north Qaidam-Qilian Mountain fault system; (2) south Qaidam-East Kunlun Mountain fault system; (3)Altun strike-slip fault system; (4)Elashan strike-slip fault system, and (5) Gansen-Xiaochaidan fault system. It is indicated that the fault systems controlled the orientation of the Qaidam basin, the formation and distribution of secondary faults within the basin,the migration of depocenters and the distribution of hydrocarbon accumulation belt.

  9. Fault Detection for Shipboard Monitoring and Decision Support Systems

    DEFF Research Database (Denmark)

    Lajic, Zoran; Nielsen, Ulrik Dam


    In this paper a basic idea of a fault-tolerant monitoring and decision support system will be explained. Fault detection is an important part of the fault-tolerant design for in-service monitoring and decision support systems for ships. In the paper, a virtual example of fault detection will be p...

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

    McLaughlin, Robert J.; Sarna-Wojcicki, Andrei M.; Wagner, David L.; Fleck, Robert J.; Langenheim, V.E.; Jachens, Robert C.; Clahan, Kevin; Allen, James R.


    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

  11. Mesoscopic Structural Observations of Cores from the Chelungpu Fault System, Taiwan Chelungpu-Fault Drilling Project Hole-A, Taiwan

    Directory of Open Access Journals (Sweden)

    Hiroki Sone


    Full Text Available Structural characteristics of fault rocks distributed within major fault zones provide basic information in understanding the physical aspects of faulting. Mesoscopic structural observations of the drilledcores from Taiwan Chelungpu-fault Drilling Project Hole-A are reported in this article to describe and reveal the distribution of fault rocks within the Chelungpu Fault System.

  12. The Morelia-Acambay Fault System (United States)

    Velázquez Bucio, M.; Soria-Caballero, D.; Garduño-Monroy, V.; Mennella, L.


    The Trans-Mexican Volcanic Belt (TMVB) is one of the most actives and representative zones of Mexico geologically speaking. Research carried out in this area gives stratigraphic, seismologic and historical evidence of its recent activity during the quaternary (Martinez and Nieto, 1990). Specifically the Morelia-Acambay faults system (MAFS) consist in a series of normal faults of dominant direction E - W, ENE - WSW y NE - SW which is cut in center west of the Trans-Mexican Volcanic Belt. This fault system appeared during the early Miocene although the north-south oriented structures are older and have been related to the activity of the tectonism inherited from the "Basin and Range" system, but that were reactivated by the east- west faults. It is believed that the activity of these faults has contributed to the creation and evolution of the longed lacustrine depressions such as: Chapala, Zacapu, Cuitzeo, Maravatio y Acambay also the location of monogenetic volcanoes that conformed the Michoacan-Guanajuato volcanic field (MGVF) and tend to align in the direction of the SFMA dominant effort. In a historical time different segments of the MAFS have been the epicenter of earthquakes from moderated to strong magnitude like the events of 1858 in Patzcuaro, Acambay in 1912, 1979 in Maravatio and 2007 in Morelia, among others. Several detailed analysis and semi-detailed analysis through a GIS platform based in the vectorial archives and thematic charts 1:50 000 scaled from the data base of the INEGI which has allowed to remark the influence of the MAFS segments about the morphology of the landscape and the identification of other structures related to the movement of the existent faults like fractures, alignments, collapses and others from the zone comprehended by the northwest of Morelia in Michoacán to the East of Acambay, Estado de México. Such analysis suggests that the fault segments possess a normal displacement plus a left component. In addition it can be

  13. A master system for power system fault phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Myung Ho; Jang, Sang Ho; Hong, Joon Hee; Min, Wan Ki; Yoo, Chang Hwan [Korea Electric Power Corp. (KEPCO), Taejon (Korea, Republic of). Research Center


    This report includes as follows - Real time digital simulator - Remote measuring, analyzing and reproducing system of power system fault data -Power system reduction method program using EMTP -Test system for protection device. (author). 22 refs., 38 figs.

  14. Guideliness for system modeling: fault tree [analysis

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yoon Hwan; Yang, Joon Eon; Kang, Dae Il; Hwang, Mee Jeong


    This document, the guidelines for system modeling related to Fault Tree Analysis(FTA), is intended to provide the guidelines with the analyzer to construct the fault trees in the level of the capability category II of ASME PRA standard. Especially, they are to provide the essential and basic guidelines and the related contents to be used in support of revising the Ulchin 3 and 4 PSA model for risk monitor within the capability category II of ASME PRA standard. Normally the main objective of system analysis is to assess the reliability of system modeled by Event Tree Analysis (ETA). A variety of analytical techniques can be used for the system analysis, however, FTA method is used in this procedures guide. FTA is the method used for representing the failure logic of plant systems deductively using AND, OR or NOT gates. The fault tree should reflect all possible failure modes that may contribute to the system unavailability. This should include contributions due to the mechanical failures of the components, Common Cause Failures (CCFs), human errors and outages for testing and maintenance. This document identifies and describes the definitions and the general procedures of FTA and the essential and basic guidelines for reving the fault trees. Accordingly, the guidelines for FTA will be capable to guide the FTA to the level of the capability category II of ASME PRA standard.

  15. Study on Knowledge -based Intelligent Fault Diagnosis of Hydraulic System

    Directory of Open Access Journals (Sweden)

    Xuexia Liu


    Full Text Available A general framework of hydraulic fault diagnosis system was studied. It consisted of equipment knowledge bases, real-time databases, fusion reasoning module, knowledge acquisition module and so on. A tree-structure model of fault knowledge was established. Fault nodes knowledge was encapsulated by object-oriented technique. Complete knowledge bases were made including fault bases and diagnosis bases. It could describe the fault positions, the structure of fault, cause-symptom relationships, diagnosis principles and other knowledge. Taking the fault of left and right lifting oil cylinder out of sync for example, the diagnostic results show that the methods were effective.

  16. Parity space-based fault diagnosis of CCBII braking system

    Institute of Scientific and Technical Information of China (English)

    黄志武; 杨迎泽; 王晶; 李赟


    Fault diagnosis is a key issue of the CCBII(computer controlled brake II) braking system, because the CCBII braking system is very complicated and nonlinear, which may exhibit isolated and multi-component coupled faults. A parity space-based method was proposed for fault diagnosis of CCBII braking systems. Firstly, the mathematical models were established according to three function modules of CCBII braking systems where the air fluid theory was utilized. Then, parity vector and threshold function were designed for each output of the system so as to identify more system faults. Fault character matrix was built based on the causal relationship between the output and the fault according to the system function and internal structure. Finally, fault detection and isolation can be realized by the comparison of the observed system output and the fault character matrix. Simulation results show that the proposed method is entirely feasible and effective.

  17. Guaranteed Cost Fault-Tolerant Control for Networked Control Systems with Sensor Faults

    Directory of Open Access Journals (Sweden)

    Qixin Zhu


    Full Text Available For the large scale and complicated structure of networked control systems, time-varying sensor faults could inevitably occur when the system works in a poor environment. Guaranteed cost fault-tolerant controller for the new networked control systems with time-varying sensor faults is designed in this paper. Based on time delay of the network transmission environment, the networked control systems with sensor faults are modeled as a discrete-time system with uncertain parameters. And the model of networked control systems is related to the boundary values of the sensor faults. Moreover, using Lyapunov stability theory and linear matrix inequalities (LMI approach, the guaranteed cost fault-tolerant controller is verified to render such networked control systems asymptotically stable. Finally, simulations are included to demonstrate the theoretical results.

  18. Study on Software Fault Injection Based on Onboard System

    Institute of Scientific and Technical Information of China (English)

    PENGJunjie; HONGBingrong; YUANChengjun; LIAiguo; WEIZhenhua; QIAOYongqiang


    Fault injection techniques are the effective methods to evaluate the dependability and validate the fault tolerance mechanisms of computer systems. Among the different fault injection techniques, software implemented fault injection technique is regarded as one of the most promising technique for evaluation of the dependability of computer systems. In this paper, combined the advantages of software fault injection and the particularity of onboard system, a new software fault injection model, which can be used to evaluate the dependability and validate the fault tolerance mechanisms of the onboard system, is put forward. To evaluate the dependability of on boardsystem effectively, the application algorithm on how to use the model is presented. The experimental results show that using the fault injection model and algorithm put forward in this paper, not only most of low-level faults such as processor register faults, memory faults and so on can be injected, but also some high-level faults such as code faults, branch faults etc. can be injected, which can be used to evaluate the dependability of the onboard systems.

  19. 3D Dynamic Rupture Simulation Across a Complex Fault System: the Mw7.0, 2010, Haiti Earthquake (United States)

    Douilly, R.; Aochi, H.; Calais, E.; Freed, A. M.


    Earthquakes ruptures sometimes take place on a secondary fault and surprisingly do not activate an adjacent major one. The 1989 Loma Prieta earthquake is a classic case where rupture occurred on a blind thrust while the adjacent San Andreas Fault was not triggered during the process. Similar to Loma Prieta, the Mw7.0, January 12 2010, Haiti earthquake also ruptured a secondary blind thrust, the Léogâne fault, adjacent to the main plate boundary, the Enriquillo Plantain Garden Fault, which did not rupture during this event. Aftershock relocalizations delineate the Léogâne rupture with two north dipping segments with slightly different dip, where the easternmost segment had mostly dip-slip motion and the westernmost one had mostly strike-slip motion. In addition, an offshore south dipping structure inferred from the aftershocks to the west of the rupture zone coincides with the offshore Trois Baies reverse fault, a region of increase in Coulomb stress increase. In this study, we investigate the rupture dynamics of the Haiti earthquake in a complex fault system of multiple segments identified by the aftershock relocations. We suppose a background stress regime that is consistent with the type of motion of each fault and with the regional tectonic regime. We initiate a nucleation on the east segment of the Léogâne fault by defining a circular region with a 2 km radius where shear stress is slightly greater than the yield stress. By varying friction on faults and background stress, we find a range of plausible scenarios. In the absence of near-field seismic records of the event, we score the different models against the static deformation field derived from GPS and InSAR at the surface. All the plausible simulations show that the rupture propagates from the eastern to the western segment along the Léogâne fault, but not on the Enriquillo fault nor on the Trois Baies fault. The best-fit simulation shows a significant increase of shear stresses on the Trois Baies


    Directory of Open Access Journals (Sweden)



    Full Text Available For the improvement of APR1400 Diverse Protection System (DPS design, the Advanced DPS (ADPS has recently been developed to enhance the fault tolerance capability of the system. Major fault masking features of the ADPS compared with the APR1400 DPS are the changes to the channel configuration and reactor trip actuation equipment. To minimize the fault occurrences within the ADPS, and to mitigate the consequences of common-cause failures (CCF within the safety I&C systems, several fault avoidance design features have been applied in the ADPS. The fault avoidance design features include the changes to the system software classification, communication methods, equipment platform, MMI equipment, etc. In addition, the fault detection, location, containment, and recovery processes have been incorporated in the ADPS design. Therefore, it is expected that the ADPS can provide an enhanced fault tolerance capability against the possible faults within the system and its input/output equipment, and the CCF of safety systems.

  1. Robust Fault Detection and Isolation for Stochastic Systems (United States)

    George, Jemin; Gregory, Irene M.


    This paper outlines the formulation of a robust fault detection and isolation scheme that can precisely detect and isolate simultaneous actuator and sensor faults for uncertain linear stochastic systems. The given robust fault detection scheme based on the discontinuous robust observer approach would be able to distinguish between model uncertainties and actuator failures and therefore eliminate the problem of false alarms. Since the proposed approach involves precise reconstruction of sensor faults, it can also be used for sensor fault identification and the reconstruction of true outputs from faulty sensor outputs. Simulation results presented here validate the effectiveness of the robust fault detection and isolation system.

  2. Data-based fault-tolerant control for affine nonlinear systems with actuator faults. (United States)

    Xie, Chun-Hua; Yang, Guang-Hong


    This paper investigates the fault-tolerant control (FTC) problem for unknown nonlinear systems with actuator faults including stuck, outage, bias and loss of effectiveness. The upper bounds of stuck faults, bias faults and loss of effectiveness faults are unknown. A new data-based FTC scheme is proposed. It consists of the online estimations of the bounds and a state-dependent function. The estimations are adjusted online to compensate automatically the actuator faults. The state-dependent function solved by using real system data helps to stabilize the system. Furthermore, all signals in the resulting closed-loop system are uniformly bounded and the states converge asymptotically to zero. Compared with the existing results, the proposed approach is data-based. Finally, two simulation examples are provided to show the effectiveness of the proposed approach.

  3. Physiochemical Evidence of Faulting Processes and Modeling of Fluid in Evolving Fault Systems in Southern California

    Energy Technology Data Exchange (ETDEWEB)

    Boles, James [Professor


    Our study targets recent (Plio-Pleistocene) faults and young (Tertiary) petroleum fields in southern California. Faults include the Refugio Fault in the Transverse Ranges, the Ellwood Fault in the Santa Barbara Channel, and most recently the Newport- Inglewood in the Los Angeles Basin. Subsurface core and tubing scale samples, outcrop samples, well logs, reservoir properties, pore pressures, fluid compositions, and published structural-seismic sections have been used to characterize the tectonic/diagenetic history of the faults. As part of the effort to understand the diagenetic processes within these fault zones, we have studied analogous processes of rapid carbonate precipitation (scaling) in petroleum reservoir tubing and manmade tunnels. From this, we have identified geochemical signatures in carbonate that characterize rapid CO2 degassing. These data provide constraints for finite element models that predict fluid pressures, multiphase flow patterns, rates and patterns of deformation, subsurface temperatures and heat flow, and geochemistry associated with large fault systems.

  4. Remote online machine fault diagnostic system (United States)

    Pan, Min-Chun; Li, Po-Ching


    The study aims at implementing a remote online machine fault diagnostic system built up in the architecture of both the BCB software-developing environment and Internet transmission communication. Variant signal-processing computation schemes for signal analysis and pattern recognition purposes are implemented in the BCB graphical user interface. Hence, machine fault diagnostic capability can be extended by using the socket application program interface as the TCP/IP protocol. In the study, the effectiveness of the developed remote diagnostic system is validated by monitoring a transmission-element test rig. A complete monitoring cycle includes data acquisition, signal processing, feature extraction, pattern recognition through the ANNs, and online video monitoring, is demonstrated.

  5. Fault isolatability conditions for linear systems

    DEFF Research Database (Denmark)

    Stoustrup, Jakob; Niemann, Henrik


    In this paper, we shall show that an unlimited number of additive single faults can be isolated under mild conditions if a general isolation scheme is applied. Multiple faults are also covered. The approach is algebraic and is based on a set representation of faults, where all faults within a set...... the faults have occurred. The last step is a fault isolation (FI) of the faults occurring in a specific fault set, i.e. equivalent with the standard FI step. A simple example demonstrates how to turn the algebraic necessary and sufficient conditions into explicit algorithms for designing filter banks, which...

  6. Estimation of Faults in DC Electrical Power System (United States)

    National Aeronautics and Space Administration — This paper demonstrates a novel optimizationbased approach to estimating fault states in a DC power system. The model includes faults changing the circuit topology...

  7. Fault Adaptive Control of Overactuated Systems Using Prognostic Estimation (United States)

    National Aeronautics and Space Administration — Most fault adaptive control research addresses the preservation of system stability or functionality in the presence of a specific failure (fault). This paper...

  8. An Immunology-inspired Fault Detection and Identification System

    Directory of Open Access Journals (Sweden)

    Liguo Weng


    Full Text Available This paper presents a fault detection and identification (FDI approach inspired by the immune system. The salient features of the immune system, such as adaptability, robustness, flexibility, archival memory and distributed cognition abilities, have been the valuable source of inspiration for fundamentally new methods for fault detection and identification. This research makes use of immunological concepts to develop a robust fault detection and identification mechanism, capable of detecting and classifying diverse system faults dynamically. Such an FDI mechanism also has the ability to learn and classify overlapping faults using distributed sensing. Moreover, its detection accuracy can be continuously improved during system operation. As tested by numerical simulations in which faults are represented by overlapping banana functions, the proposed algorithms are adaptive to new types of faults and overlapping faults.

  9. Fault-Tolerant Control for Networked Control Systems with Limited Information in Case of Actuator Fault


    Wang Yan-feng; Wang Pei-liang; Li Zu-xin; Chen Hui-ying


    This paper is concerned with the problem of designing a fault-tolerant controller for uncertain discrete-time networked control systems against actuator possible fault. The step difference between the running step k and the time stamp of the used plant state is modeled as a finite state Markov chain of which the transition probabilities matrix information is limited. By introducing actuator fault indicator matrix, the closed-loop system model is obtained by means of state augmentation techniq...

  10. Study of fault injection system based on software

    Institute of Scientific and Technical Information of China (English)


    A software fault injection system SFIS is designed, which consists of the target system plus a fault injector, fault library, workload, data collector, and data analyzer. A serial communication mechanism is adopted to simulate the factual work environment. Then a fault model is built for single particle event, which can be denoted as FM = (FL, FT). FL stands for fault location, and FT stands for fault type. The fault model supports three temporal faults: transient, intermittent, and permanent. During the experiments implemented by SFIS,the software interruption method is adopted to inject transient faults, and step trace method is adopted to inject permanent faults into the target system. The experiment results indicate that for the injected transient code segment faults, 2.8% of them do not affect the program output, 80.1% of them are detected by the built-in error detection in the system, and 17.1% of them are not detected by fault detection mechanism. The experiment results verify the validity of the fault injection method.

  11. Robust fault diagnosis for a class of nonlinear systems

    Institute of Scientific and Technical Information of China (English)

    Zhanshan WANG; Huaguang ZHANG


    Robust fault diagnosis based on adaptive observer is studied for a class of nonlinear systems up to output injection. Adaptive fault updating laws are designed to guarantee the stability of the diagnosis system. The upper bounds of the state estimation error and fault estimation error of the adaptive observer are given respectively and the effects of parameter in the adaptive updating laws on fault estimation accuracy are also discussed. Simulation example demonstrates the effectiveness of the proposed methods and the analysis results.

  12. Data-driven design of fault diagnosis and fault-tolerant control systems

    CERN Document Server

    Ding, Steven X


    Data-driven Design of Fault Diagnosis and Fault-tolerant Control Systems presents basic statistical process monitoring, fault diagnosis, and control methods, and introduces advanced data-driven schemes for the design of fault diagnosis and fault-tolerant control systems catering to the needs of dynamic industrial processes. With ever increasing demands for reliability, availability and safety in technical processes and assets, process monitoring and fault-tolerance have become important issues surrounding the design of automatic control systems. This text shows the reader how, thanks to the rapid development of information technology, key techniques of data-driven and statistical process monitoring and control can now become widely used in industrial practice to address these issues. To allow for self-contained study and facilitate implementation in real applications, important mathematical and control theoretical knowledge and tools are included in this book. Major schemes are presented in algorithm form and...

  13. Fault reactivation: The Picuris-Pecos fault system of north-central New Mexico (United States)

    McDonald, David Wilson

    The PPFS is a N-trending fault system extending over 80 km in the Sangre de Cristo Mountains of northern New Mexico. Precambrian basement rocks are offset 37 km in a right-lateral sense; however, this offset includes dextral strike-slip (Precambrian), mostly normal dip-slip (Pennsylvanian), mostly reverse dip-slip (Early Laramide), limited strike-slip (Late Laramide) and mostly normal dip-slip (Cenozoic). The PPFS is broken into at least 3 segments by the NE-trending Embudo fault and by several Laramide age NW-trending tear faults. These segments are (from N to S): the Taos, the Picuris, and the Pecos segments. On the east side of the Picuris segment in the Picuris Mountains, the Oligocene-Miocene age Miranda graben developed and represents a complex extension zone south of the Embudo fault. Regional analysis of remotely sensed data and geologic maps indicate that lineaments subparallel to the trace of the PPFS are longer and less frequent than lineaments that trend orthogonal to the PPFS. Significant cross cutting faults and subtle changes in fault trends in each segment are clear in the lineament data. Detailed mapping in the eastern Picuris Mountains showed that the favorably oriented Picuris segment was not reactivated in the Tertiary development of the Rio Grande rift. Segmentation of the PPFS and post-Laramide annealing of the Picuris segment are interpreted to have resulted in the development of the subparallel La Serna fault. The Picuris segment of the PPFS is offset by several E-ESE trending faults. These faults are Late Cenozoic in age and interpreted to be related to the uplift of the Picuris Mountains and the continuing sinistral motion on the Embudo fault. Differential subsidence within the Miranda graben caused the development of several synthetic and orthogonal faults between the bounding La Serna and Miranda faults. Analysis of over 10,000 outcrop scale brittle structures reveals a strong correlation between faults and fracture systems. The dominant

  14. The San Andreas Transform System and the Tectonics of California: An Alternative Approach (United States)

    Platt, J. P.; Kaus, B.; Becker, T. W.


    Pacific - North America displacement in California is distributed over a zone of intracontinental deformation 400 km wide, and incorporates large regions of transtensional and transpressional deformation. This pattern of deformation is not easily explicable in terms of brittle Coulomb failure, which should localize deformation on to a single fault. There is no consensus at present on what controls the width of this zone or the distribution of strain within it. We model the transform as a weak ductile shear zone, terminating at either end in an effectively stress-free boundary. The shear zone exerts a shear-stress boundary condition on the stronger but deformable continental lithosphere either side. Stress and strain-rate decrease away from the shear zone because of its limited length in relation to the scale of the plates. Force balance in a sheet of deformable material with free upper and lower surfaces requires lateral gradients in horizontal shear-strain rate to be balanced by longitudinal gradients in horizontal stretching rate. Analytical estimates and 3D numerical modeling demonstrate that these gradients will create zones of lithospheric thickening and thinning distributed anti-symmetrically about the shear zone. Lithospheric thickening in the Transverse Ranges and the Klamath Mountains, and thinning in the Eastern California shear zone and the San Francisco Bay area, correspond reasonably well to these predictions. This provides a test for the length- scales concept, and a powerful predictive tool for understanding the tectonics of California and other intracontinental transforms.

  15. Fault tolerant architecture for artificial olfactory system (United States)

    Lotfivand, Nasser; Nizar Hamidon, Mohd; Abdolzadeh, Vida


    In this paper, to cover and mask the faults that occur in the sensing unit of an artificial olfactory system, a novel architecture is offered. The proposed architecture is able to tolerate failures in the sensors of the array and the faults that occur are masked. The proposed architecture for extracting the correct results from the output of the sensors can provide the quality of service for generated data from the sensor array. The results of various evaluations and analysis proved that the proposed architecture has acceptable performance in comparison with the classic form of the sensor array in gas identification. According to the results, achieving a high odor discrimination based on the suggested architecture is possible.

  16. Distributed Fault-Tolerant Control of Networked Uncertain Euler-Lagrange Systems Under Actuator Faults. (United States)

    Chen, Gang; Song, Yongduan; Lewis, Frank L


    This paper investigates the distributed fault-tolerant control problem of networked Euler-Lagrange systems with actuator and communication link faults. An adaptive fault-tolerant cooperative control scheme is proposed to achieve the coordinated tracking control of networked uncertain Lagrange systems on a general directed communication topology, which contains a spanning tree with the root node being the active target system. The proposed algorithm is capable of compensating for the actuator bias fault, the partial loss of effectiveness actuation fault, the communication link fault, the model uncertainty, and the external disturbance simultaneously. The control scheme does not use any fault detection and isolation mechanism to detect, separate, and identify the actuator faults online, which largely reduces the online computation and expedites the responsiveness of the controller. To validate the effectiveness of the proposed method, a test-bed of multiple robot-arm cooperative control system is developed for real-time verification. Experiments on the networked robot-arms are conduced and the results confirm the benefits and the effectiveness of the proposed distributed fault-tolerant control algorithms.

  17. Robust Parametric Fault Estimation in a Hopper System

    DEFF Research Database (Denmark)

    Soltani, Mohsen; Izadi-Zamanabadi, Roozbeh; Wisniewski, Rafal;


    The ability of diagnosis of the possible faults is a necessity for satellite launch vehicles during their mission. In this paper, a structural analysis method is employed to divide the complex propulsion system into simpler subsystems for fault diagnosis filter design. A robust fault diagnosis me...

  18. Mesoscopic Structural Observations of Cores from the Chelungpu Fault System, Taiwan Chelungpu-Fault Drilling Project Hole-A, Taiwan

    Directory of Open Access Journals (Sweden)

    Hiroki Sone


    Full Text Available Structural characteristics of fault rocks distributed within major fault zones provide basic information in understanding the physical aspects of faulting. Mesoscopic structural observations of the drilled cores from Taiwan Chelungpu-fault Drilling Project Hole-A are reported in this article to describe and reveal the distribution of fault rocks within the Chelungpu Fault System. The Chelungpu Fault System in Hole-A was encountered at a depth of between 1050 - 1250 m where deformation structures increased. Three major fault zone structures were found at approximate depths of 1111, 1153, and 1221 m. The presence of wide fault rock regions were mostly concentrated in these 3 fault zones. The fault zone at 1111 m mainly consists of a nearly brecciated fracture zone and a clayey fault gouge zone of about 1.05 m in thickness. Fault rocks from the fault zone at 1153 m are characterized by the presence of sand grains in the matrix content, consisting of a 1.1-m thick fault breccia zone and a 0.35-m thick fault gouge zone. The fault zone at 1221 m consists of fault breccia and fault gouge of 1.15 m in total thickness. These are relatively harder and darker in color than the previous 2 fault zones. Each of the 3 fault zones contains a few layers of dark colored rocks of approximately 5 - 80 mm in thickness within the fault breccia and fault gouge zones. These dark colored rocks were found distinctively within the fault rocks. However, there relation to the process of faulting is not clearly understood and shall be discussed in detail with the aid of microscopic observations.

  19. Faults (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Through the study of faults and their effects, much can be learned about the size and recurrence intervals of earthquakes. Faults also teach us about crustal...

  20. Fault detection for discrete-time switched systems with sensor stuck faults and servo inputs. (United States)

    Zhong, Guang-Xin; Yang, Guang-Hong


    This paper addresses the fault detection problem of switched systems with servo inputs and sensor stuck faults. The attention is focused on designing a switching law and its associated fault detection filters (FDFs). The proposed switching law uses only the current states of FDFs, which guarantees the residuals are sensitive to the servo inputs with known frequency ranges in faulty cases and robust against them in fault-free case. Thus, the arbitrarily small sensor stuck faults, including outage faults can be detected in finite-frequency domain. The levels of sensitivity and robustness are measured in terms of the finite-frequency H- index and l2-gain. Finally, the switching law and FDFs are obtained by the solution of a convex optimization problem.

  1. Fault-tolerant Actuator System for Electrical Steering of Vehicles

    DEFF Research Database (Denmark)

    Sørensen, Jesper Sandberg; Blanke, Mogens


    Being critical to the safety of vehicles, the steering system is required to maintain the vehicles ability to steer until it is brought to halt, should a fault occur. With electrical steering becoming a cost-effective candidate for electrical powered vehicles, a fault-tolerant architecture...... is needed that meets this requirement. This paper studies the fault-tolerance properties of an electrical steering system. It presents a fault-tolerant architecture where a dedicated AC motor design used in conjunction with cheap voltage measurements can ensure detection of all relevant faults...... in the steering system. The paper shows how active control reconfiguration can accommodate all critical faults. The fault-tolerant abilities of the steering system are demonstrated on the hardware of a warehouse truck....

  2. San Francisco Bay Area Fault Observations Displayed in Google Earth (United States)

    Lackey, H.; Hernandez, M.; Nayak, P.; Zapata, I.; Schumaker, D.


    According to the United States Geological Survey (USGS), the San Francisco Bay Area has a 62% probability of experiencing a major earthquake in the next 30 years. The Hayward fault and the San Andreas fault are the two main faults in the Bay Area that are capable of producing earthquakes of magnitude 6.7 or larger - a size that could profoundly affect many of the 7 million people who live in the Bay Area. The Hayward fault has a 27% probability of producing a major earthquake in next 30 years, and the San Andreas fault has a 21% probability. Our research group, which is part of the SF-ROCKS high school outreach program, studied the Hayward and San Andreas faults. The goal of our project was to observe these faults at various locations, measure the effects of creep, and to present the data in Google Earth, a freeware tool for the public to easily view and interact with these and other seismic-hazard data. We examined the Hayward and San Andreas faults (as mapped by USGS scientists) in Google Earth to identify various sites where we could possibly find evidence of fault creep. We next visited these sites in the field where we mapped the location using a hand- held Global Positioning System, identified and photographed fault evidence, and measured offset features with a ruler or tape measure. Fault evidence included en echelon shears in pavement, warped buildings, and offset features such as sidewalks. Fault creep offset measurements range from 1.5 19 cm. We also identified possible evidence of fault creep along the San Andreas fault in South San Francisco where it had not been previously described. In Google Earth, we plotted our field sites, linked photographs showing evidence of faulting, and included detailed captions to explain the photographs. We will design a webpage containing the data in a Keyhole Markup Language (KML) file format for display in Google Earth. Any interested person needs only to download the free version of Google Earth software and visit our

  3. Mine-Hoist Active Fault Tolerant Control System and Strategy

    Institute of Scientific and Technical Information of China (English)

    WANG Zhi-jie; WANG Yao-cai; MENG Jiang; ZHAO Peng-cheng; CHANG Yan-wei


    Based on fault diagnosis and fault tolerant technologies, the mine-hoist active fault-tolerant control system (MAFCS) is presented with corresponding strategies,, which includes the fault diagnosis module (FDM), the dynamic library (DL) and the fault-tolerant control module (FCM). When a fault is judged from some sensor by FDM, FCM reconfigure the state of MAFCS by calling the parameters from all sub libraries in DL, in order to ensure the reliability and safety of mine hoist. The simulating result shows that, MAFCS is of certain intelligence, which can adopt the corresponding control strategies according to different fault modes, even when there are quite difference between the real data and the prior fault modes.

  4. Global strike-slip faults: Bounds from plate tectonics (United States)

    Gordon, R. G.; Argus, D. F.


    According to the tenets of plate tectonics, a transform fault is a strike-slip fault along which neither convergence nor divergence occurs. Analysis of global plate motion data indicates that the only true transform faults are the strike-slip faults that offset segments of mid-ocean ridges. Thus, many of Earth's major strike-slip fault systems are not true transform faults as they accommodate large components of oblique convergence or oblique divergence. This is particularly true for several important ocean-continent systems such as the San Andreas, the strike-slip systems bounding the northern and southern Caribbean plate, the Alpine fault system of New Zealand, the Anatolian fault system, and the Azores-Gibraltar-Alboran sea system. These strike-slip systems are commonly sites of large scale mountain building and basin formation. Here we examine the far-field constraints on the motions of the plates bounding several of these strike-slip systems using both conventional plate motion circuits and results from global positioning system and other space geodetic data. We pay particular attention to the San Andreas fault system in central and northern California, where the San Andreas system is part of the boundary between the Sierran microplate and the Pacific plate. Most of the fault system accommodates obliquely convergent motion, giving rise to the California Coast Range, but in the northern San Francisco Bay Area it is obliquely divergent, producing San Pablo Bay and a gap in the Coast Range that permits the Sierran watershed to drain to the Pacific through the Golden Gate.

  5. Novel Fault Diagnosis Scheme for HVDC System via ESO

    Institute of Scientific and Technical Information of China (English)

    YAN Bing-yong; TIAN Zuo-hua; SHI Song-jiao


    A novel fault detection and identification (FDI) scheme for HVDC (High Voltage Direct Current Transmission) system was presented. It was based on the unique active disturbance rejection concept, where the HVDC system faults were estimated using an extended states observer (ESO). Firstly, the mathematical model of HVDC system was constructed, where the system states and disturbance were treated as an extended state. An augment HVDC system was established by using the extended state in rectify side and converter side, respectively. Then, a fault diagnosis filter was established to diagnose the HVDC system faults via the ESO theory. The evolution of the extended state in the augment HVDC system can reflect the actual system faults and disturbances, which can be used for the fault diagnosis purpose. A novel feature of this approach is that it can simultaneously detect and identify the shape and magnitude of the HVDC faults and disturbance. Finally, different kinds of HVDC faults were simulated to illustrate the feasibility and effectiveness of the proposed ESO based FDI approach. Compared with the neural network based or support vector machine based FDI approach, the ESO based FDI scheme can reduce the fault detection time dramatically and track the actual system fault accurately. What's more important, it needs not do complex online calculations and the training of neural network so that it can be applied into practice.

  6. Teatrikunstnik Andrea Haamer: Olen alati unistanud Eestisse tagasi tulla / Andrea Haamer ; intervjueerinud Andreas Sepp, Anneli Sihvart

    Index Scriptorium Estoniae

    Haamer, Andrea


    Eesti juurtega lava- ja kostüümikunstnikust Andrea T. Haamerist, kes on Eestis kujundanud kolm balletti. 25. veebruaril avatavast neljandast Jõhvi balletifestivalist, kus avatakse Andrea Haameri näitus

  7. Method and system for environmentally adaptive fault tolerant computing (United States)

    Copenhaver, Jason L. (Inventor); Jeremy, Ramos (Inventor); Wolfe, Jeffrey M. (Inventor); Brenner, Dean (Inventor)


    A method and system for adapting fault tolerant computing. The method includes the steps of measuring an environmental condition representative of an environment. An on-board processing system's sensitivity to the measured environmental condition is measured. It is determined whether to reconfigure a fault tolerance of the on-board processing system based in part on the measured environmental condition. The fault tolerance of the on-board processing system may be reconfigured based in part on the measured environmental condition.

  8. Fault tolerant highly reliable inertial navigation system (United States)

    Jeerage, Mahesh; Boettcher, Kevin

    This paper describes a development of failure detection and isolation (FDI) strategies for highly reliable inertial navigation systems. FDI strategies are developed based on the generalized likelihood ratio test (GLRT). A relationship between detection threshold and false alarm rate is developed in terms of the sensor parameters. A new method for correct isolation of failed sensors is presented. Evaluation of FDI performance parameters, such as false alarm rate, wrong isolation probability, and correct isolation probability, are presented. Finally a fault recovery scheme capable of correcting false isolation of good sensors is presented.

  9. Bond graph model-based fault diagnosis of hybrid systems

    CERN Document Server

    Borutzky, Wolfgang


    This book presents a bond graph model-based approach to fault diagnosis in mechatronic systems appropriately represented by a hybrid model. The book begins by giving a survey of the fundamentals of fault diagnosis and failure prognosis, then recalls state-of-art developments referring to latest publications, and goes on to discuss various bond graph representations of hybrid system models, equations formulation for switched systems, and simulation of their dynamic behavior. The structured text: • focuses on bond graph model-based fault detection and isolation in hybrid systems; • addresses isolation of multiple parametric faults in hybrid systems; • considers system mode identification; • provides a number of elaborated case studies that consider fault scenarios for switched power electronic systems commonly used in a variety of applications; and • indicates that bond graph modelling can also be used for failure prognosis. In order to facilitate the understanding of fault diagnosis and the presented...

  10. Fault Diagnosis of Power Systems Using Intelligent Systems (United States)

    Momoh, James A.; Oliver, Walter E. , Jr.


    The power system operator's need for a reliable power delivery system calls for a real-time or near-real-time Al-based fault diagnosis tool. Such a tool will allow NASA ground controllers to re-establish a normal or near-normal degraded operating state of the EPS (a DC power system) for Space Station Alpha by isolating the faulted branches and loads of the system. And after isolation, re-energizing those branches and loads that have been found not to have any faults in them. A proposed solution involves using the Fault Diagnosis Intelligent System (FDIS) to perform near-real time fault diagnosis of Alpha's EPS by downloading power transient telemetry at fault-time from onboard data loggers. The FDIS uses an ANN clustering algorithm augmented with a wavelet transform feature extractor. This combination enables this system to perform pattern recognition of the power transient signatures to diagnose the fault type and its location down to the orbital replaceable unit. FDIS has been tested using a simulation of the LeRC Testbed Space Station Freedom configuration including the topology from the DDCU's to the electrical loads attached to the TPDU's. FDIS will work in conjunction with the Power Management Load Scheduler to determine what the state of the system was at the time of the fault condition. This information is used to activate the appropriate diagnostic section, and to refine if necessary the solution obtained. In the latter case, if the FDIS reports back that it is equally likely that the faulty device as 'start tracker #1' and 'time generation unit,' then based on a priori knowledge of the system's state, the refined solution would be 'star tracker #1' located in cabinet ITAS2. It is concluded from the present studies that artificial intelligence diagnostic abilities are improved with the addition of the wavelet transform, and that when such a system such as FDIS is coupled to the Power Management Load Scheduler, a faulty device can be located and isolated

  11. Simple model for fault-charged hydrothermal systems

    Energy Technology Data Exchange (ETDEWEB)

    Bodvarsson, G.S.; Miller, C.W.; Benson, S.M.


    A two-dimensional transient model of fault-charged hydrothermal systems has been developed. The model can be used to analyze temperature data from fault-charged hydrothermal systems, estimate the recharge rate from the fault, and determine how long the system has been under natural development. The model can also be used for theoretical studies of the development of fault-controlled hydrothermal systems. The model has been tentatively applied to the low-temperature hydrothermal system at Susanville, California. A resonable match was obtained with the observed temperature data, and a hot water recharge rate of 9 x 10{sup -6} m{sup 3}s/m was calculated.

  12. Fault detection filter design for stochastic time-delay systems with sensor faults (United States)

    Li, Xiao-Jian; Yang, Guang-Hong


    This article considers the fault detection (FD) problem for a class of Itô-type stochastic time-delay systems subject to external disturbances and sensor faults. The main objective is to design a fault detection filter (FDF) such that it has prescribed levels of disturbance attenuation and fault sensitivity. Sufficient conditions for guaranteeing these levels are formulated in terms of linear matrix inequalities (LMIs), and the corresponding fault detection filter design is cast into a convex optimisation problem which can be efficiently handled by using standard numerical algorithms. In order to reduce the conservatism of filter design with mixed objectives, multi-Lyapunov functions approach is used via Projection Lemma. In addition, it is shown that our results not only include some previous conditions characterising H ∞ performance and H - performance defined for linear time-invariant (LTI) systems as special cases but also improve these conditions. Finally, two examples are employed to illustrate the effectiveness of the proposed design scheme.

  13. Fault Diagnosis and Fault-tolerant Control of Modular Multi-level Converter High-voltage DC System: A Review

    DEFF Research Database (Denmark)

    Liu, Hui; Ma, Ke; Wang, Chao;


    Modular Multilevel Converter based High Voltage Direct Current (MMC-HVDC) configuration is a promising solution for the efficient grid integration and bulky power transmission over long distance. However, the large number of series connected identical modules in MMC may increase the probability...... strategies of MMC-HVDC systems for the most common faults happened in MMC-HVDC systems covering MMC faults, DC side faults as well as AC side faults. An important part of this paper is devoted to a discussion of the vulnerable spots as well as failure mechanism of the MMC-HVDC system covering switching...... device fault, DC line faults as well as AC grid faults. Special attention is given to the comparison of the corresponding fault diagnosis and fault-tolerant control approaches. Further, focus is dedicated to control/protection strategies and topologies with fault ride-though capability for MMC...

  14. Summarize of Electric Vehicle Electric System Fault and Fault-tolerant Technology

    Directory of Open Access Journals (Sweden)

    Zhang Liwei


    Full Text Available Electric vehicle drive system is a multi-variable function, running environment complexed and changeable system, so it’s failure form is complicated. In this paper, according to the fault happens in different position, establish vehicle fault table, analyze the consequences of failure may cause and the causes of failure. Combined with hardware limitations, and the maximum guarantee system performance requirements, passive software redundancy fault-tolerant strategy is put forward, give an example to analysis the pros and cons of this method.

  15. Fault evolution-test dependency modeling for mechanical systems

    Institute of Scientific and Technical Information of China (English)

    Xiao-dong TAN; Jian-lu LUO; Qing LI; Bing LU; Jing QIU


    Tracking the process of fault growth in mechanical systems using a range of tests is important to avoid catastrophic failures. So, it is necessary to study the design for testability (DFT). In this paper, to improve the testability performance of me-chanical systems for tracking fault growth, a fault evolution-test dependency model (FETDM) is proposed to implement DFT. A testability analysis method that considers fault trackability and predictability is developed to quantify the testability performance of mechanical systems. Results from experiments on a centrifugal pump show that the proposed FETDM and testability analysis method can provide guidance to engineers to improve the testability level of mechanical systems.

  16. Characterization of the faulted behavior of digital computers and fault tolerant systems (United States)

    Bavuso, Salvatore J.; Miner, Paul S.


    A development status evaluation is presented for efforts conducted at NASA-Langley since 1977, toward the characterization of the latent fault in digital fault-tolerant systems. Attention is given to the practical, high speed, generalized gate-level logic system simulator developed, as well as to the validation methodology used for the simulator, on the basis of faultable software and hardware simulations employing a prototype MIL-STD-1750A processor. After validation, latency tests will be performed.

  17. Progressive Fault Accommodation for Time-delay Systems with Parametric Faults

    Institute of Scientific and Technical Information of China (English)

    WU Jun-sheng; WENG Zheng-xin; TIAN Zuo-hua


    The fault accommodation problem for time-delay system is studied in this paper. The progressive accommodation strategy based on the Newton-Raphson scheme is proposed to solve this problem. This accommodation scheme can significantly reduces the loss of performance and risk associated with system instability which results from the time-delay needed by fault accommodation aigorithms to provide a solution. Simulation results are given to illustrate the efficiency of the provided method.

  18. Active Fault Diagnosis in Sampled-data Systems

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Poulsen, Niels Kjølstad


    The focus in this paper is on active fault diagnosis (AFD) in closed-loop sampleddata systems. Applying the same AFD architecture as for continuous-time systems does not directly result in the same set of closed-loop matrix transfer functions. For continuous-time systems, the LFT (linear fractional...... transformation) structure in the connection between the parametric faults and the matrix transfer function (also known as the fault signature matrix) applied for AFD is not directly preserved for sampled-data system. As a consequence of this, the AFD methods cannot directly be applied for sampled-data systems....... Two methods are considered in this paper to handle the fault signature matrix for sampled-data systems such that standard AFD methods can be applied. The first method is based on a discretization of the system such that the LFT structure is preserved resulting in the same LFT structure in the fault...

  19. Morphostructural study of the Belledonne faults system (French Alps). (United States)

    Billant, Jérémy; Bellier, Olivier; Hippolyte, Jean-Claude; Godard, Vincent; Manchuel, Kevin


    The NE trending Belledonne faults system, located in the Alps, is a potentially active faults system that extends from the Aiguilles Rouges and Mont Blanc massifs in the NE to the Vercors massif in the SW (subalpine massifs). It includes the Belledonne border fault (BBF), defined by an alignment of micro earthquakes (ML≤3.5) along the eastern part of the Grésivaudan valley (Thouvenot et al., 2003). Focal mechanisms and their respective depths tend to confirm a dextral strike-slip faulting at crustal scale. In the scope of the Sigma project (, EDF), this study aims at better constraining the geometry, kinematic and seismogenic potential of the constitutive faults of the Belledonne fault system, by using a multidisciplinary approach that includes tectonics, geomorphology and geophysics. Fault kinematic analysis along the BBF (Billant et al., 2015) and the Jasneuf fault allows the determination of a strike-slip tectonic regime characterised by an ENE trending σ1 stress axes, which is consistent with stress state deduced from the focal mechanisms. Although no morphological anomalies could be related to recent faulting along the BBF, new clues of potential Quaternary deformations were observed along the other faults of the system: -right lateral offset of morphologic markers (talwegs...) along the NE trending Arcalod fault located at the north-eastern terminations of the BBF; -left lateral offset of the valley formed by the Isère glacier along the NW trending Brion fault which is consistent with its left-lateral slip inferred from the focal mechanisms; -fault scarps and right lateral offsets of cliffs bordering a calcareous plateau and talwegs along the four fault segments of the NE trending Jasneuf fault located at the south-western termination of the BBF in the Vercors massif. Some offsets were measured using a new method that does not require the identification of piercing points and take advantage of the high resolution

  20. Fault-Tolerant Control for Networked Control Systems with Limited Information in Case of Actuator Fault

    Directory of Open Access Journals (Sweden)

    Wang Yan-feng


    Full Text Available This paper is concerned with the problem of designing a fault-tolerant controller for uncertain discrete-time networked control systems against actuator possible fault. The step difference between the running step k and the time stamp of the used plant state is modeled as a finite state Markov chain of which the transition probabilities matrix information is limited. By introducing actuator fault indicator matrix, the closed-loop system model is obtained by means of state augmentation technique. The sufficient conditions on the stochastic stability of the closed-loop system are given and the fault-tolerant controller is designed by solving a linear matrix inequality. A numerical example is presented to illustrate the effectiveness of the proposed method.

  1. The Andrea Levialdi Fellowship (United States)

    Fieschi, Roberto

    My first encounter with Cuba dates back to winter 1967-1968 at the Cultural Congress of La Havana, a very large international event to promote greater understanding of the reality of the Cuban Revolution. In fact the person invited was my friend and colleague Andrea Levialdi (Andrea already knew Cuba and loved it) who, unable to participate, allowed me to go in her place. So I landed at the airport of the "first free country in Latin America" with the delegation of the Italian Communist Party. In Havana I met other Italian physicists whom I already knew, among them Bruno Vitale and Daniele Amati. They, like me, were embarrassed by the generous hospitality of `Havana Libre,' especially in a country which was going through such difficulties. Despite our best efforts we did not succeed in receiving a more modest welcome.

  2. Model-based fault diagnosis in PEM fuel cell systems

    Energy Technology Data Exchange (ETDEWEB)

    Escobet, T.; de Lira, S.; Puig, V.; Quevedo, J. [Automatic Control Department (ESAII), Universitat Politecnica de Catalunya (UPC), Rambla Sant Nebridi 10, 08222 Terrassa (Spain); Feroldi, D.; Riera, J.; Serra, M. [Institut de Robotica i Informatica Industrial (IRI), Consejo Superior de Investigaciones Cientificas (CSIC), Universitat Politecnica de Catalunya (UPC) Parc Tecnologic de Barcelona, Edifici U, Carrer Llorens i Artigas, 4-6, Planta 2, 08028 Barcelona (Spain)


    In this work, a model-based fault diagnosis methodology for PEM fuel cell systems is presented. The methodology is based on computing residuals, indicators that are obtained comparing measured inputs and outputs with analytical relationships, which are obtained by system modelling. The innovation of this methodology is based on the characterization of the relative residual fault sensitivity. To illustrate the results, a non-linear fuel cell simulator proposed in the literature is used, with modifications, to include a set of fault scenarios proposed in this work. Finally, it is presented the diagnosis results corresponding to these fault scenarios. It is remarkable that with this methodology it is possible to diagnose and isolate all the faults in the proposed set in contrast with other well known methodologies which use the binary signature matrix of analytical residuals and faults. (author)

  3. Application of Ferrography to Fault Diagnosis of Hydraulic Systems

    Institute of Scientific and Technical Information of China (English)


    This paper deals with research on the successful use of ferrography as a wear measurement method for condition monitoring and fault diagnosis of hydraulic systems.The analysis program and progression is discussed, and a case study for condition monitoring and fault diagnosis of hydraulic systems by means of ferrography is also reviewed.

  4. Fault Tolerant Controllers for Sampled-data Systems

    DEFF Research Database (Denmark)

    Niemann, H.; Stoustrup, Jakob


    A general compensator architecture for fault tolerant control (FTC) for sampled-data systems is proposed. The architecture is based on the YJBK parameterization of all stabilizing controllers, and uses the dual YJBK parameterization to quantify the performance of the fault tolerant system. The FTC...

  5. Fault tolerant controllers for sampled-data systems

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Stoustrup, Jakob


    A general compensator architecture for fault tolerant control (FTC) for sampled-data systems is proposed. The architecture is based on the YJBK parameterization of all stabilizing controllers, and uses the dual YJBK parameterization to quantify the performance of the fault tolerant system. The FTC...

  6. A Complete Analytic Model for Fault Diagnosis of Power Systems

    Institute of Scientific and Technical Information of China (English)

    LIU Daobing; GU Xueping; LI Haipeng


    Interconnections of the modem bulk electric power systems, while contributing to the operating economy and reliability by means of mutual assistance between the subsystems, result in an increased complexity of fault diagnosis and a more serious consequence of misdiagnosis. The online fault diagnosis has become a more challenging problem for dispatchers to operate a power system securely,

  7. Fault Tolerance in Distributed Systems using Fused State Machines


    Balasubramanian, Bharath; Vijay K Garg


    Replication is a standard technique for fault tolerance in distributed systems modeled as deterministic finite state machines (DFSMs or machines). To correct f crash or f/2 Byzantine faults among n different machines, replication requires nf additional backup machines. We present a solution called fusion that requires just f additional backup machines. First, we build a framework for fault tolerance in DFSMs based on the notion of Hamming distances. We introduce the concept of an (f,m)-fusion...

  8. Non deterministic finite automata for power systems fault diagnostics

    Directory of Open Access Journals (Sweden)

    LINDEN, R.


    Full Text Available This paper introduces an application based on finite non-deterministic automata for power systems diagnosis. Automata for the simpler faults are presented and the proposed system is compared with an established expert system.

  9. Modeling and Fault Simulation of Propellant Filling System (United States)

    Jiang, Yunchun; Liu, Weidong; Hou, Xiaobo


    Propellant filling system is one of the key ground plants in launching site of rocket that use liquid propellant. There is an urgent demand for ensuring and improving its reliability and safety, and there is no doubt that Failure Mode Effect Analysis (FMEA) is a good approach to meet it. Driven by the request to get more fault information for FMEA, and because of the high expense of propellant filling, in this paper, the working process of the propellant filling system in fault condition was studied by simulating based on AMESim. Firstly, based on analyzing its structure and function, the filling system was modular decomposed, and the mathematic models of every module were given, based on which the whole filling system was modeled in AMESim. Secondly, a general method of fault injecting into dynamic system was proposed, and as an example, two typical faults - leakage and blockage - were injected into the model of filling system, based on which one can get two fault models in AMESim. After that, fault simulation was processed and the dynamic characteristics of several key parameters were analyzed under fault conditions. The results show that the model can simulate effectively the two faults, and can be used to provide guidance for the filling system maintain and amelioration.

  10. Satisfactory fault-tolerant controller design for uncertain systems subject to actuator faults

    Institute of Scientific and Technical Information of China (English)

    Zhang Dengfeng; Su Hongye; Wang Zhiquan


    Based on satisfactory control strategy, a new method for robust passive fault tolerant controller is proposed for a class of uncertain discrete-time systems subject to actuator faults. The state-feedback gain matrix is calculated by linear matrix inequality (LMI) technique. The designed controller guarantees that the closed-loop system meets the pre-specified consistent constraints on circular pole index and steady-state variance index simultaneously for normal case and possible actuator fault case. The consistency of the performance indices is discussed. Furthermore, with the mentioned indices constraints, a solution is obtained by convex optimal technique for the robust satisfactory fault-tolerant controller with optimal control-cost.

  11. Fault Severity Evaluation and Improvement Design for Mechanical Systems Using the Fault Injection Technique and Gini Concordance Measure

    Directory of Open Access Journals (Sweden)

    Jianing Wu


    Full Text Available A new fault injection and Gini concordance based method has been developed for fault severity analysis for multibody mechanical systems concerning their dynamic properties. The fault tree analysis (FTA is employed to roughly identify the faults needed to be considered. According to constitution of the mechanical system, the dynamic properties can be achieved by solving the equations that include many types of faults which are injected by using the fault injection technique. Then, the Gini concordance is used to measure the correspondence between the performance with faults and under normal operation thereby providing useful hints of severity ranking in subsystems for reliability design. One numerical example and a series of experiments are provided to illustrate the application of the new method. The results indicate that the proposed method can accurately model the faults and receive the correct information of fault severity. Some strategies are also proposed for reliability improvement of the spacecraft solar array.

  12. Regional Geologic Map of San Andreas and Related Faults in Carrizo Plain, Temblor, Caliente and La Panza Ranges and Vicinity, California; A Digital Database (United States)

    Dibblee, T. W.; Digital database compiled by Graham, S. E.; Mahony, T.M.; Blissenbach, J.L.; Mariant, J.J.; Wentworth, C.M.


    This Open-File Report is a digital geologic map database. The report serves to introduce and describe the digital data. There is no paper map included in the Open-File Report. The report includes PostScript and PDF plot files that can be used to plot images of the geologic map sheet and explanation sheet. This digital map database is prepared from a previously published map by Dibblee (1973). The geologic map database delineates map units that are identified by general age, lithology, and clast size following the stratigraphic nomenclature of the U.S. Geological Survey. For descriptions of the units, their stratigraphic relations, and sources of geologic mapping, consult the explanation sheet ( or of99-14_4d.pdf), or the original published paper map (Dibblee, 1973). The scale of the source map limits the spatial resolution (scale) of the database to 1:125,000 or smaller. For those interested in the geology of Carrizo Plain and vicinity who do not use an ARC/INFO compatible Geographic Information System (GIS), but would like to obtain a paper map and explanation, PDF and PostScript plot files containing map images of the data in the digital database, as well as PostScript and PDF plot files of the explanation sheet and explanatory text, have been included in the database package (please see the section 'Digital Plot Files', page 5). The PostScript plot files require a gzip utility to access them. For those without computer capability, we can provide users with the PostScript or PDF files on tape that can be taken to a vendor for plotting. Paper plots can also be ordered directly from the USGS (please see the section 'Obtaining Plots from USGS Open-File Services', page 5). The content and character of the database, methods of obtaining it, and processes of extracting the map database from the tar (tape archive) file are described herein. The map database itself, consisting of six ARC/INFO coverages, can be obtained over the Internet or by magnetic tape

  13. Sensor Fault Tolerant Generic Model Control for Nonlinear Systems

    Institute of Scientific and Technical Information of China (English)


    A modified Strong Tracking Filter (STF) is used to develop a new approach to sensor fault tolerant control. Generic Model Control (GMC) is used to control the nonlinear process while the process runs normally because of its robust control performance. If a fault occurs in the sensor, a sensor bias vector is then introduced to the output equation of the process model. The sensor bias vector is estimated on-line during every control period using the STF. The estimated sensor bias vector is used to develop a fault detection mechanism to supervise the sensors. When a sensor fault occurs, the conventional GMC is switched to a fault tolerant control scheme, which is, in essence, a state estimation and output prediction based GMC. The laboratory experimental results on a three-tank system demonstrate the effectiveness of the proposed Sensor Fault Tolerant Generic Model Control (SFTGMC) approach.

  14. Fault Diagnosis of Nonlinear Systems Using Structured Augmented State Models

    Institute of Scientific and Technical Information of China (English)

    Jochen Aβfalg; Frank Allg(o)wer


    This paper presents an internal model approach for modeling and diagnostic functionality design for nonlinear systems operating subject to single- and multiple-faults. We therefore provide the framework of structured augmented state models. Fault characteristics are considered to be generated by dynamical exosystems that are switched via equality constraints to overcome the augmented state observability limiting the number of diagnosable faults. Based on the proposed model, the fault diagnosis problem is specified as an optimal hybrid augmented state estimation problem. Sub-optimal solutions are motivated and exemplified for the fault diagnosis of the well-known three-tank benchmark. As the considered class of fault diagnosis problems is large, the suggested approach is not only of theoretical interest but also of high practical relevance.

  15. Optimal Robust Fault Detection for Linear Discrete Time Systems

    Directory of Open Access Journals (Sweden)

    Nike Liu


    Full Text Available This paper considers robust fault-detection problems for linear discrete time systems. It is shown that the optimal robust detection filters for several well-recognized robust fault-detection problems, such as ℋ−/ℋ∞, ℋ2/ℋ∞, and ℋ∞/ℋ∞ problems, are the same and can be obtained by solving a standard algebraic Riccati equation. Optimal filters are also derived for many other optimization criteria and it is shown that some well-studied and seeming-sensible optimization criteria for fault-detection filter design could lead to (optimal but useless fault-detection filters.

  16. Fast isolation of faults in transmission systems using current transients

    Energy Technology Data Exchange (ETDEWEB)

    Perera, N.; Rajapakse, A.D. [University of Manitoba, Department of Electrical and Computer Engineering, Engineering Building, 15 Gillson Street, Winnipeg, Manitoba (Canada)


    This paper presents a protection scheme that is capable of very fast isolation of faults in high voltage transmission systems. Proposed scheme comprises set of relays connected through a telecommunication network, located at different nodes of the system. Relays use wavelet coefficients of current signals to identify the fault directions relative to their location. Fault directions identified at different locations in the system can be combined to determine the faulted line (or busbar) and isolate it. A robust single ended traveling wave based fault distance estimation approach is proposed as a backup in case of communication failure. Investigations were carried out using time domain simulations in PSCAD/EMTDC for a high voltage transmission system. (author)

  17. A fault-tolerant software strategy for digital systems (United States)

    Hitt, E. F.; Webb, J. J.


    Techniques developed for producing fault-tolerant software are described. Tolerance is required because of the impossibility of defining fault-free software. Faults are caused by humans and can appear anywhere in the software life cycle. Tolerance is effected through error detection, damage assessment, recovery, and fault treatment, followed by return of the system to service. Multiversion software comprises two or more versions of the software yielding solutions which are examined by a decision algorithm. Errors can also be detected by extrapolation from previous results or by the acceptability of results. Violations of timing specifications can reveal errors, or the system can roll back to an error-free state when a defect is detected. The software, when used in flight control systems, must not impinge on time-critical responses. Efforts are still needed to reduce the costs of developing the fault-tolerant systems.

  18. Hybrid fault diagnosis of nonlinear systems using neural parameter estimators. (United States)

    Sobhani-Tehrani, E; Talebi, H A; Khorasani, K


    This paper presents a novel integrated hybrid approach for fault diagnosis (FD) of nonlinear systems taking advantage of both the system's mathematical model and the adaptive nonlinear approximation capability of computational intelligence techniques. Unlike most FD techniques, the proposed solution simultaneously accomplishes fault detection, isolation, and identification (FDII) within a unified diagnostic module. At the core of this solution is a bank of adaptive neural parameter estimators (NPEs) associated with a set of single-parameter fault models. The NPEs continuously estimate unknown fault parameters (FPs) that are indicators of faults in the system. Two NPE structures, series-parallel and parallel, are developed with their exclusive set of desirable attributes. The parallel scheme is extremely robust to measurement noise and possesses a simpler, yet more solid, fault isolation logic. In contrast, the series-parallel scheme displays short FD delays and is robust to closed-loop system transients due to changes in control commands. Finally, a fault tolerant observer (FTO) is designed to extend the capability of the two NPEs that originally assumes full state measurements for systems that have only partial state measurements. The proposed FTO is a neural state estimator that can estimate unmeasured states even in the presence of faults. The estimated and the measured states then comprise the inputs to the two proposed FDII schemes. Simulation results for FDII of reaction wheels of a three-axis stabilized satellite in the presence of disturbances and noise demonstrate the effectiveness of the proposed FDII solutions under partial state measurements.

  19. Fault-Tolerant Systems with Concurrent Error-Locating Capability

    Institute of Scientific and Technical Information of China (English)

    JIANG JianHui(江建慧); MIN YingHua(闵应骅); PENG ChengLian(彭澄廉)


    Fault-tolerant systems have found wide applications in military, industrial andcommercial areas. Most of these systems are constructed by multiple-modular redundancy or er-ror control coding techniques. They need some fault-tolerant specific components (such as voter,switcher, encoder, or decoder) to implement error-detecting or error-correcting functions. However,the problem of error detection, location or correction for fault-tolerance specific components them-selves has not been solved properly so far. Thus, the dependability of a whole fault-tolerant systemwill be greatly affected. This paper presents a theory of robust fault-masking digital circuits forcharacterizing fault-tolerant systems with the ability of concurrent error location and a new schemeof dual-modular redundant systems with partially robust fault-masking property. A basic robustfault-masking circuit is composed of a basic functional circuit and an error-locating corrector. Sucha circuit not only has the ability of concurrent error correction, but also has the ability of concurrenterror location. According to this circuit model, for a partially robust fault-masking dual-modularredundant system, two redundant modules based on alternating-complementary logic consist of thebasic functional circuit. An error-correction specific circuit named as alternating-complementarycorrector is used as the error-locating corrector. The performance (such as hardware complexity,time delay) of the scheme is analyzed.

  20. Reconfigurable Control of Input Affine Nonlinear Systems under Actuator Fault

    DEFF Research Database (Denmark)

    Tabatabaeipour, Mojtaba; Galeazzi, Roberto


    This paper proposes a fault tolerant control method for input-affine nonlinear systems using a nonlinear reconfiguration block (RB). The basic idea of the method is to insert the RB between the plant and the nominal controller such that fault tolerance is achieved without re-designing the nominal...

  1. All-to-all sequenced fault detection system (United States)

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


    An apparatus, program product and method enable nodal fault detection by sequencing communications between all system nodes. A master node may coordinate communications between two slave nodes before sequencing to and initiating communications between a new pair of slave nodes. The communications may be analyzed to determine the nodal fault.

  2. A Fault-tolerant Development Methodology for Industrial Control Systems

    DEFF Research Database (Denmark)

    Izadi-Zamanabadi, Roozbeh; Thybo, C.


    and logically sound manner. This paper presents the employe fault-tolerant development methodology and highlights steps, which have been essential for achieving complete and consistent monitoring capabilities. Fault diagnosis for a commercial refrigeration system is treated as a case-study....

  3. Comparing fault susceptibility of multiple ISAs and operating systems (United States)

    Chyłek, Sławomir


    This paper presents a research that aims to compare effects of faults on different configurations of computer systems. The study covers comparison of susceptibility to faults of x86, AMD64, ARM, PowerPC, MIPS architectures and Linux, FreeBSD, Minix operating systems. An emulation based software implemented fault injection technique was used to perform experiments. The problem of choosing an adequate number of tests in experiments is followed by report with collected results where multiple aspects of test runs were analyzed: providing correct computation result, availability of the system under test and error messages. The research allows to determine characteristics of susceptibility to faults of each platform and is a first step towards designing new fault tolerance solutions and assessing their effectiveness.

  4. Adaptive Observer-Based Fault Estimate for Nonlinear Systems

    Institute of Scientific and Technical Information of China (English)

    ZONG Qun; LIU Wenjing; LIU Li


    An approach for adaptive observer-based fault estimate for nonlinear system is proposed.H-infinity theory is applied to analyzing the design method and stable conditions of the adaptive observer,from which both system state and fault can be estimated.It is proved that the fault estimate error is related to the given H-infinity track performance indexes,as well as to the changing rate of the fault and the Lipschitz constant of the nonlinear item.The design steps of the adaptive observer are proposed.The simulation results show that the observer has good performance for fault estimate even when the system includes nonlinear terms,which confirms the effectiveness of the method.

  5. A new GPS velocity field for the Pacific Plate - Part 2: implications for fault slip rates in western California (United States)

    DeMets, C.; Márquez-Azúa, Bertha; Cabral-Cano, Enrique


    Lower and upper bounds for present deformation rates across faults in central California between the San Andreas Fault and Pacific coast are estimated from a new Global Positioning System (GPS) velocity field for central, western California in light of geodetic evidence presented in a companion paper for slow, but significant deformation within the Pacific Plate between young seafloor in the eastern Pacific and older seafloor elsewhere on the plate. Transects of the GPS velocity field across the San Andreas Fault between Parkfield and San Juan Buatista, where fault slip is dominated by creep and the velocity field thus reveals the off-fault deformation, show that GPS sites in westernmost California move approximately parallel to the fault at an average rate of 3.4 ± 0.4 mm yr-1 relative to the older interior of the Pacific Plate, but only 1.8 ± 0.6 mm yr-1 if the Pacific Plate frame of reference is corrected for deformation within the plate. Modelled interseismic elastic deformation from the weakly coupled creeping segment of the San Andreas Fault is an order-of-magnitude too small to explain the southeastward motions of coastal sites in western California. Similarly, models that maximize residual viscoelastic deformation from the 1857 Fort Tejon and 1906 San Francisco earthquakes mismatch both the rates and directions of GPS site motions in central California relative to the Pacific Plate. Neither thus explains the site motions southwest of the San Andreas fault, indicating that the site motions measure deformation across faults and folds outboard of the San Andreas Fault. The non-zero site velocities thus constitute strong evidence for active folding and faulting outboard from the creeping segment of the San Andreas Fault and suggest limits of 0-2 mm yr-1 for the Rinconada Fault slip rate and 1.8 ± 0.6 to 3.4 ± 0.4 mm yr-1 for the slip rates integrated across near-coastal faults such as the Hosgri, San Gregorio and San Simeon faults.

  6. Navigation System Fault Diagnosis for Underwater Vehicle

    DEFF Research Database (Denmark)

    Falkenberg, Thomas; Gregersen, Rene Tavs; Blanke, Mogens


    This paper demonstrates fault diagnosis on unmanned underwater vehicles (UUV) based on analysis of structure of the nonlinear dynamics. Residuals are generated using dierent approaches in structural analysis followed by statistical change detection. Hypothesis testing thresholds are made signal b...

  7. Andrea Levialdi in Memoriam (United States)

    Waisman, Dina

    Professor Andrea Levialdi was born in Bologna Italy in 1911, son of a very modest scientist who at the time was active in the socialist ranks. From an early age Levialdi felt the contradictions between the bourgeois environment surrounding him and his family's deep antifascism. He earned a doctorate in mathematics and physics at the University of Rome in 1937 with a dissertation on photoelasticity, methods and applications. Soon after, he was awarded a scholarship for specializing in optics at the Arcetri National Optics Institute (Florence).

  8. Robust fault detection for switched linear systems with state delays. (United States)

    Wang, Dong; Wang, Wei; Shi, Peng


    This correspondence deals with the problem of robust fault detection for discrete-time switched systems with state delays under an arbitrary switching signal. The fault detection filter is used as the residual generator, in which the filter parameters are dependent on the system mode. Attention is focused on designing the robust fault detection filter such that, for unknown inputs, control inputs, and model uncertainties, the estimation error between the residuals and faults is minimized. The problem of robust fault detection is converted into an H(infinity)-filtering problem. By a switched Lyapunov functional approach, a sufficient condition for the solvability of this problem is established in terms of linear matrix inequalities. A numerical example is provided to demonstrate the effectiveness of the proposed method.

  9. Fault tolerant system design for uninterruptible power supplies

    Directory of Open Access Journals (Sweden)

    B. Y. Volochiy


    Full Text Available The problem of design for reliability of a fault tolerant system for uninterruptible power supplies is considered. Configuration of a fault tolerant system determines the structure of an uninterruptible power supply: power supply built from modules of the same type, stand-by sliding reserve for them, twice total reserve of the power supply with two accumulator batteries, the controls and diagnostics means. The developed tool for automated analytical model of fault tolerant systems generation and illustration of its capabilities in determination of requirements for repair service and accumulator batteries are given.

  10. Newly-generated Daliangshan Fault Zone—Shortcutting on the central section of Xianshuihe-Xiaojiang fault system

    Institute of Scientific and Technical Information of China (English)

    IKEDA; Yasutaka; TOGO; Masayoshi; TAJIKARA; Masayoshi; ECHIGO; Tomoo; OKADA; Shinsuke


    The Daliangshan fault zone is the eastern branch in the central section of Xianshuihe-Xiaojiang fault system. It has been neglected for a long time, partly because of no destructive earthquake records along this fault zone. On the other hand, it is located on the remote and inaccessible plateau. So far it was excluded as part of the Xianshuihe-Xiaojiang fault system. Based on the interpretation of aerophotographs and field investigations, we document this fault zone in detail, and give an estimation of strike-slip rate about 3 mm/a in Late Quaternary together with age dating data. The results suggest that the Daliangshan fault zone is a newly-generated fault zone resulted from shortcutting in the central section of Xianshuihe-Xiaojiang fault system because of the clockwise rotation of the Southeastern Tibetan Crustal Block, which is bounded by the Xianshuihe-Xiaojiang fault system. Moreover, the shortcutting may make the Daliangshan fault zone replace the Anninghe and Zemuhe fault zones gradually, and finally, the later two fault zones will probably die out with the continuous clockwise rotation.

  11. Robust fault diagnosis for a class of nonlinear systems with time delay

    Institute of Scientific and Technical Information of China (English)


    Robust fault diagnosis problems based on adaptive observer technique are studied for a class of time delayed nonlinear system with external disturbance. Adaptive fault updating laws were designed to estimate the fault and to guarantee the stability of the diagnosis system. The effects of adjusting parameters in adaptive fault updating laws on the fault estimation accuracy were analyzed. For a designed fault diagnosis system, the super bounds of the state estimation error and fault estimation error of the adaptive observer were discussed, which further showed how the parameters in the adaptive fault updating laws influenced the fault estimation accuracy.Simulation example demonstrates the effectiveness of the proposed methods and the analysis results.

  12. Axo: Masking Delay Faults in Real-Time Control Systems


    Maaz, Mashood Mohiuddin; Saab, Wajeb; Bliudze, Simon; Le Boudec, Jean-Yves


    We consider real-time control systems that consist of a controller that computes and sends setpoints to be implemented in physical processes through process agents. We focus on systems that use commercial off-the-shelf hardware and software components. Setpoints of these systems have strict real-time constraints: Implementing a setpoint after its deadline, or not receiving setpoints within a deadline, can cause failure. In this paper, we address delay faults: faults that cause setpoints to vi...

  13. Robust Fault Diagnosis Algorithm for a Class of Nonlinear Systems

    Directory of Open Access Journals (Sweden)

    Hai-gang Xu


    Full Text Available A kind of robust fault diagnosis algorithm to Lipschitz nonlinear system is proposed. The novel disturbances constraint condition of the nonlinear system is derived by group algebra method, and the novel constraint condition can meet the system stability performance. Besides, the defined robust performance index of fault diagnosis observer guarantees the robust. Finally, the effectiveness of the algorithm proposed is proved in the simulations.

  14. PCA Fault Feature Extraction in Complex Electric Power Systems

    Directory of Open Access Journals (Sweden)

    ZHANG, J.


    Full Text Available Electric power system is one of the most complex artificial systems in the world. The complexity is determined by its characteristics about constitution, configuration, operation, organization, etc. The fault in electric power system cannot be completely avoided. When electric power system operates from normal state to failure or abnormal, its electric quantities (current, voltage and angles, etc. may change significantly. Our researches indicate that the variable with the biggest coefficient in principal component usually corresponds to the fault. Therefore, utilizing real-time measurements of phasor measurement unit, based on principal components analysis technology, we have extracted successfully the distinct features of fault component. Of course, because of the complexity of different types of faults in electric power system, there still exists enormous problems need a close and intensive study.

  15. Suppression of strike-slip fault systems (United States)

    Curren, I. S.


    In orogens elongated parallel to a great circle about the Euler pole for the two bounding plates, theory requires simple-shear deformation in the form of distributed deformation or velocity discontinuities across strike-slip faults. This type of deformation, however, does not develop at all plate boundaries requiring toroidal motion. Using the global plate boundary model, PB2002 [Bird, 2003], as the basis for identifying areas where expected simple-shear deformation is absent or underdeveloped, it was also possible to identify two potential causes for this behavior: (1) the presence of extensive fracturing at right angles to the shear plane and (2) regional cover of flood basalts or andesites with columnar joints. To test this hypothesis, a new plane-stress finite-strain model was developed to study the effects of such pre-existing structures on the development of simple shear in a clay cake. A homogenous kaolinite-water mixture was poured into a deforming parallelogram box and partially dried to allow for brittle and plastic deformation at and below the surface of the clay, respectively. This was floated on a dense fluid foundation, effectively removing basal friction, and driven by a motor in a sinistral direction from the sides of the box. Control experiments produced classic Riedel model fault assemblages and discrete, through-going primary deformation zones (PDZs); experiments with pre-existing structures developed the same, though subdued and distributed, fault assemblages but did not develop through-going PDZs. Although formation of strike-slip faults was underdeveloped at the surface in clay with pre-existing structures, offset within the clay cake (measured, with respect to a fixed point, by markers on the clay surface) as a fraction of total offset of the box was consistently larger than that of the control experiments. This suggests that while the extent of surface faulting was lessened in clay with pre-existing structures, slip was still occurring at

  16. FaultBuster: data driven fault detection and diagnosis for industrial systems

    DEFF Research Database (Denmark)

    Bergantino, Nicola; Caponetti, Fabio; Longhi, Sauro


    Efficient and reliable monitoring systems are mandatory to assure the required security standards in industrial complexes. This paper describes the recent developments of FaultBuster, a purely data-driven diagnostic system. It is designed so to be easily scalable to different monitor tasks....... Multivariate statistical models based on principal components are used to detect abnormal situations. Tailored to alarms, a probabilistic inference engine process the fault evidences to output the most probable diagnosis. Results from the DX 09 Diagnostic Challenge shown strong detection properties, while...

  17. Study on Missile Intelligent Fault Diagnosis System Based on Fuzzy NN Expert System

    Institute of Scientific and Technical Information of China (English)


    In order to study intelligent fault diagnosis methods based on fuzzy neural network (NN) expert systemand build up intelligent fault diagnosis for a type of mis-sile weapon system, the concrete implementation of a fuzzyNN fault diagnosis expert system is given in this paper. Based on thorough research of knowledge presentation, theintelligent fault diagnosis system is implemented with artificial intelligence for a large-scale missile weapon equipment.The method is an effective way to perform fuzzy fault diagnosis. Moreover, it provides a new way of the fault diagnosisfor large-scale missile weapon equipment.

  18. Subsurface structure and kinematics of the Calaveras-Hayward fault stepover from three-dimensional Vp and seismicity, San Francisco Bay region, California (United States)

    Manaker, David M.; Michael, Andrew J.; Burgmann, Roland


    The Calaveras and Hayward faults are major components of the San Andreas fault system in the San Francisco Bay region. Dextral slip is presumed to transfer from the Calaveras fault to the Hayward fault in the Mission Hills region, an area of uplift in the contractional stepover between the two faults. Here the estimated deep slip rates drop from 15 to 6 mm/yr on the Calaveras fault, and slip begins on the Hayward fault at an estimated 9 mm/yr. A lineament of microseismicity near the Mission fault links the seismicity on the Calaveras and Hayward faults and is presumed to be related directly to this slip transfer. However, geologic and seismologic evidence suggest that the Mission fault may not be the source of the seismicity and that the Mission fault is not playing a major role in the slip transfer.

  19. A Robust Fault Detection Approach for Nonlinear Systems

    Institute of Scientific and Technical Information of China (English)

    Min-Ze Chen; Qi Zhao; Dong-Hua Zhou


    In this paper, we study the robust fault detection problem of nonlinear systems. Based on the Lyapunov method,a robust fault detection approach for a general class of nonlinear systems is proposed. A nonlinear observer is first provided,and a sufficient condition is given to make the observer locally stable. Then, a practical algorithm is presented to facilitate the realization of the proposed observer for robust fault detection. Finally, a numerical example is provided to show the effectiveness of the proposed approach.

  20. Fault Location in Power Electrical Traction Line System

    Directory of Open Access Journals (Sweden)

    Yimin Zhou


    Full Text Available In this paper, methods of fault location are discussed in electrical traction single-end direct power supply network systems. Based on the distributed parameter model of the system, the position of the short-circuit fault can be located with the aid of the current and voltage value at the measurement end of the electrical traction line. Furthermore, the influence of the transient resistance, the position of the locomotive, locomotive load for fault location are also discussed. MATLAB simulation tool is used for the simulation experiments. Simulation results are proved the effectiveness of the proposed algorithms.

  1. An intelligent online fault diagnostic scheme for nonlinear systems

    Institute of Scientific and Technical Information of China (English)

    Hing Tung MOK; Che Wai CHAN; Zaiyue YANG


    An online fault diagnostic scheme for nonlinear systems based on neurofuzzy networks is proposed in this paper.The scheme involves two stages.In the first stage,the nonlinear system is approximated by a neurofuzzy network,which is trained offline from data obtained during the normal operation of the system.In the second stage,residual is generated online from this network and is modelled by another neurofuzzy network trained online.Fuzzy rules are extracted from this network,and are compared with those in the fault database obmined under different faulty operations,from which faults are diagnosed.The performance of the proposed intelligent fault scheme is illustrated using a two.tank water level control system under different faulty conditions.

  2. Fault Injection and Monitoring Capability for a Fault-Tolerant Distributed Computation System (United States)

    Torres-Pomales, Wilfredo; Yates, Amy M.; Malekpour, Mahyar R.


    The Configurable Fault-Injection and Monitoring System (CFIMS) is intended for the experimental characterization of effects caused by a variety of adverse conditions on a distributed computation system running flight control applications. A product of research collaboration between NASA Langley Research Center and Old Dominion University, the CFIMS is the main research tool for generating actual fault response data with which to develop and validate analytical performance models and design methodologies for the mitigation of fault effects in distributed flight control systems. Rather than a fixed design solution, the CFIMS is a flexible system that enables the systematic exploration of the problem space and can be adapted to meet the evolving needs of the research. The CFIMS has the capabilities of system-under-test (SUT) functional stimulus generation, fault injection and state monitoring, all of which are supported by a configuration capability for setting up the system as desired for a particular experiment. This report summarizes the work accomplished so far in the development of the CFIMS concept and documents the first design realization.

  3. Global positioning system reoccupation of early triangulation sites - Tectonic deformation of the Southern Coast Ranges (United States)

    Shen, Zheng-Kang; Jackson, David D.


    We study tectonic deformation in the Southern Coast Range, California. We use triangulation and astronomic azimuth data collected since 1875, trilateration since 1970, and global positioning system data collected from 1986 to 1987. Two modeling techniques have been used. An elastic block-fault model is applied to study the tectonic motion of the San Andreas Fault and the San Gregorio-Hosgri Fault. Station velocities are modeled to study regional deformations. Results show that the regional deformation is predominantly controlled by deep strike-slip motion along the San Andreas Fault, at a rate of 33 +/- 2 mm/yr. Deep slip along the San Gregorio-Hosgri Fault is about 0-4 mm/yr, assuming a locked suit to a depth of 20 km. Convergence normal to the San Andreas Fault in the Southern Coast Ranges is not greater than 0.02 microrad/yr.


    Institute of Scientific and Technical Information of China (English)


    Fault detection and diagnosis for pneumatic system of automatic production line are studied. An expert system using fuzzy-neural network and pneumatic circuit fault diagnosis instrument are designed. The mathematical model of various pneumatic faults and experimental device are built. In the end, some experiments are done, which shows that the expert system using fuzzy-neural network can diagnose fast and truly fault of pneumatic circuit.

  5. Fault detection in rotor bearing systems using time frequency techniques (United States)

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


    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.

  6. Adaptive Vibration Control System for MR Damper Faults

    Directory of Open Access Journals (Sweden)

    Juan C. Tudón-Martínez


    Full Text Available Several methods have been proposed to estimate the force of a semiactive damper, particularly of a magnetorheological damper because of its importance in automotive and civil engineering. Usually, all models have been proposed assuming experimental data in nominal operating conditions and some of them are estimated for control purposes. Because dampers are prone to fail, fault estimation is useful to design adaptive vibration controllers to accommodate the malfunction in the suspension system. This paper deals with the diagnosis and estimation of faults in an automotive magnetorheological damper. A robust LPV observer is proposed to estimate the lack of force caused by a damper leakage in a vehicle corner. Once the faulty damper is isolated in the vehicle and the fault is estimated, an Adaptive Vibration Control System is proposed to reduce the fault effect using compensation forces from the remaining healthy dampers. To fulfill the semiactive damper constraints in the fault adaptation, an LPV controller is designed for vehicle comfort and road holding. Simulation results show that the fault observer has good performance with robustness to noise and road disturbances and the proposed AVCS improves the comfort up to 24% with respect to a controlled suspension without fault tolerance features.

  7. All row, planar fault detection system (United States)

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


    An apparatus, program product and method for detecting nodal faults may simultaneously cause designated nodes of a cell to communicate with all nodes adjacent to each of the designated nodes. Furthermore, all nodes along the axes of the designated nodes are made to communicate with their adjacent nodes, and the communications are analyzed to determine if a node or connection is faulty.

  8. Multi-directional fault detection system (United States)

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


    An apparatus, program product and method checks for nodal faults in a group of nodes comprising a center node and all adjacent nodes. The center node concurrently communicates with the immediately adjacent nodes in three dimensions. The communications are analyzed to determine a presence of a faulty node or connection.

  9. Soft-Fault Detection Technologies Developed for Electrical Power Systems (United States)

    Button, Robert M.


    The NASA Glenn Research Center, partner universities, and defense contractors are working to develop intelligent power management and distribution (PMAD) technologies for future spacecraft and launch vehicles. The goals are to provide higher performance (efficiency, transient response, and stability), higher fault tolerance, and higher reliability through the application of digital control and communication technologies. It is also expected that these technologies will eventually reduce the design, development, manufacturing, and integration costs for large, electrical power systems for space vehicles. The main focus of this research has been to incorporate digital control, communications, and intelligent algorithms into power electronic devices such as direct-current to direct-current (dc-dc) converters and protective switchgear. These technologies, in turn, will enable revolutionary changes in the way electrical power systems are designed, developed, configured, and integrated in aerospace vehicles and satellites. Initial successes in integrating modern, digital controllers have proven that transient response performance can be improved using advanced nonlinear control algorithms. One technology being developed includes the detection of "soft faults," those not typically covered by current systems in use today. Soft faults include arcing faults, corona discharge faults, and undetected leakage currents. Using digital control and advanced signal analysis algorithms, we have shown that it is possible to reliably detect arcing faults in high-voltage dc power distribution systems (see the preceding photograph). Another research effort has shown that low-level leakage faults and cable degradation can be detected by analyzing power system parameters over time. This additional fault detection capability will result in higher reliability for long-lived power systems such as reusable launch vehicles and space exploration missions.

  10. Historical Seismicity of the Algeciras Fault System, Southwestern Colombia (United States)

    Chicangana, G.; Gomez-Capera, A.; Salcedo-Hurtado, E.


    The Algeciras Fault System (AFS) is located in the Eastern Cordillera south western Colombia. This fault system has been allocated at least four big earthquakes in the last 230 years. In this work we describe the macroseismic intensities of these earthquakes not only to its epicentral zone but also in others places as Bogotá metropolitan area far from AFS more of 200 km. The AFS is shaped by three thrust faults. From north to south these are Guayuriba Fault with with 160 km of lengh, the Algeciras Fault with 149 km of lengh, and the Garzon - Pitalito Fault with 128 km of lengh. The big earthquakes, whose macroseismic data are analyzed here, its that of the 1785 (M=6.8) event, for which the Guayuriba Fault was related; it caused heavy damage in Bogotá and Neiva. This fault also produced the 1917 (6.9Ms) earthquake which significantly affected to Bogotá and Villavicencio. The 1967 earthquake (7.2Mw) is related to the Algeciras Fault; this event was very destructive in rural villages of Huila Department and caused significant damage in Bogotá and Neiva. With the latter earthquake high vulnerability was evident in the Bogota metropolitan area front to a large event ocurred by this fault system. The 16 November 1827 (M=7.3) earthquake ocurred on the Garzon - Pitalito Fault and was felt throughout the whole Andean region of Colombia. This event produced high intensities both in Bogota like in Popayan, Neiva, Pasto and where today are located the cities of Armenia, Manizales and Pereira toward west of Colombia. These lattest cities were founded in the second half of nineteen century after happened this earthquake. From historical seismicity review, we can determine the scope of seismic hazard for this fault system which not only affects its area of influence but also the center and west of the country, a región inhabited by more than 65% of the population of Colombia.

  11. Fault Detection in Systems-A Fuzzy Approach

    Directory of Open Access Journals (Sweden)

    Ashok Kumar


    Full Text Available The task of fault detection is important when dealing with failures of crucial nature. After detection of faults in a system, it is advisable to suggest maintenance action before occurrenceof a failure. Fault detection may be done by observing various symptoms of the system during its operational stage. Sometimes, symptoms cannot be quantified easily but can be expressedin linguistic terms. Since linguistic terms are fuzzy quantifiers, these can be represented by fuzzy numbers. In this paper, two cases have been discussed, where a fault likely to affect a particular systemlsystems, is detected. In the first case, this is done by means of a compositional rule of inference. The second case is based on modified similarity measure. For both these  cases, linguistic terms have been expressed as trapezoidal fuzzy numbers

  12. A Diagnostic System for Speed-Varying Motor Rotary Faults

    Directory of Open Access Journals (Sweden)

    Chwan-Lu Tseng


    Full Text Available This study proposed an intelligent rotary fault diagnostic system for motors. A sensorless rotational speed detection method and an improved dynamic structural neural network are used. Moreover, to increase the convergence speed of training, a terminal attractor method and a hybrid discriminant analysis are also adopted. The proposed method can be employed to detect the rotary frequencies of motors with varying speeds and can enhance the discrimination of motor faults. To conduct the experiments, this study used wireless sensor nodes to transmit vibration data and employed MATLAB to write codes for functional modules, including the signal processing, sensorless rotational speed estimation, neural network, and stochastic process control chart. Additionally, Visual Basic software was used to create an integrated human-machine interface. The experimental results regarding the test of equipment faults indicated that the proposed novel diagnostic system can effectively estimate rotational speeds and provide superior ability of motor fault discrimination with fast training convergence.

  13. Robust filtering and fault detection of switched delay systems

    CERN Document Server

    Wang, Dong; Wang, Wei


    Switched delay systems appear in a wide field of applications including networked control systems, power systems, memristive systems. Though the large amount of ideas with respect to such systems have generated, until now, it still lacks a framework to focus on filter design and fault detection issues which are relevant to life safety and property loss. Beginning with the comprehensive coverage of the new developments in the analysis and control synthesis for switched delay systems, the monograph not only provides a systematic approach to designing the filter and detecting the fault of switched delay systems, but it also covers the model reduction issues. Specific topics covered include: (1) Arbitrary switching signal where delay-independent and delay-dependent conditions are presented by proposing a linearization technique. (2) Average dwell time where a weighted Lyapunov function is come up with dealing with filter design and fault detection issues beside taking model reduction problems. The monograph is in...

  14. Development of CIMS and FMS in Faults Diagnosis System

    Institute of Scientific and Technical Information of China (English)


    The research and practice of CIMS and FMS has brought about a great development to advanced manufacturing systems for decades. The experience of failure and success during the process of development is a revelation and reference for the design of a fault diagnosis system. This paper focuses on its function of directing to the design of a fault diagnosis system in terms of the flexibility of the system, the human's importance in the system, and the design of a distributed system. In view of the tendency of CIMS and FMS, the article also states the principle that the new fault diagnosis system should be improved by enhancing hardware in software, remote Internet service, and sustainable development.

  15. Fault tolerant hypercube computer system architecture (United States)

    Madan, Herb S. (Inventor); Chow, Edward (Inventor)


    A fault-tolerant multiprocessor computer system of the hypercube type comprising a hierarchy of computers of like kind which can be functionally substituted for one another as necessary is disclosed. Communication between the working nodes is via one communications network while communications between the working nodes and watch dog nodes and load balancing nodes higher in the structure is via another communications network separate from the first. A typical branch of the hierarchy reporting to a master node or host computer comprises, a plurality of first computing nodes; a first network of message conducting paths for interconnecting the first computing nodes as a hypercube. The first network provides a path for message transfer between the first computing nodes; a first watch dog node; and a second network of message connecting paths for connecting the first computing nodes to the first watch dog node independent from the first network, the second network provides an independent path for test message and reconfiguration affecting transfers between the first computing nodes and the first switch watch dog node. There is additionally, a plurality of second computing nodes; a third network of message conducting paths for interconnecting the second computing nodes as a hypercube. The third network provides a path for message transfer between the second computing nodes; a fourth network of message conducting paths for connecting the second computing nodes to the first watch dog node independent from the third network. The fourth network provides an independent path for test message and reconfiguration affecting transfers between the second computing nodes and the first watch dog node; and a first multiplexer disposed between the first watch dog node and the second and fourth networks for allowing the first watch dog node to selectively communicate with individual ones of the computing nodes through the second and fourth networks; as well as, a second watch dog node

  16. On the design of fault-tolerant robotic manipulator systems (United States)

    Tesar, Delbert


    Robotic systems are finding increasing use in space applications. Many of these devices are going to be operational on board the Space Station Freedom. Fault tolerance has been deemed necessary because of the criticality of the tasks and the inaccessibility of the systems to maintenance and repair. Design for fault tolerance in manipulator systems is an area within robotics that is without precedence in the literature. In this paper, we will attempt to lay down the foundations for such a technology. Design for fault tolerance demands new and special approaches to design, often at considerable variance from established design practices. These design aspects, together with reliability evaluation and modeling tools, are presented. Mechanical architectures that employ protective redundancies at many levels and have a modular architecture are then studied in detail. Once a mechanical architecture for fault tolerance has been derived, the chronological stages of operational fault tolerance are investigated. Failure detection, isolation, and estimation methods are surveyed, and such methods for robot sensors and actuators are derived. Failure recovery methods are also presented for each of the protective layers of redundancy. Failure recovery tactics often span all of the layers of a control hierarchy. Thus, a unified framework for decision-making and control, which orchestrates both the nominal redundancy management tasks and the failure management tasks, has been derived. The well-developed field of fault-tolerant computers is studied next, and some design principles relevant to the design of fault-tolerant robot controllers are abstracted. Conclusions are drawn, and a road map for the design of fault-tolerant manipulator systems is laid out with recommendations for a 10 DOF arm with dual actuators at each joint.

  17. GEMS: A Fault Tolerant Grid Job Management System


    Tadepalli, Sriram Satish


    The Grid environments are inherently unstable. Resources join and leave the environment without any prior notification. Application fault detection, checkpointing and restart is of foremost importance in the Grid environments. The need for fault tolerance is especially acute for large parallel applications since the failure rate grows with the number of processors and the duration of the computation. A Grid job management system hides the heterogeneity of the Grid and the complexity of the ...

  18. Fault diagnosis and fault-tolerant control strategies for non-linear systems analytical and soft computing approaches

    CERN Document Server

    Witczak, Marcin


      This book presents selected fault diagnosis and fault-tolerant control strategies for non-linear systems in a unified framework. In particular, starting from advanced state estimation strategies up to modern soft computing, the discrete-time description of the system is employed Part I of the book presents original research results regarding state estimation and neural networks for robust fault diagnosis. Part II is devoted to the presentation of integrated fault diagnosis and fault-tolerant systems. It starts with a general fault-tolerant control framework, which is then extended by introducing robustness with respect to various uncertainties. Finally, it is shown how to implement the proposed framework for fuzzy systems described by the well-known Takagi–Sugeno models. This research monograph is intended for researchers, engineers, and advanced postgraduate students in control and electrical engineering, computer science,as well as mechanical and chemical engineering.

  19. Interseismic interactions in geometrically complex fault systems: Implications for San Francisco Bay Area fault creep and tectonics (United States)

    Evans, E. L.; Meade, B. J.; Loveless, J. P.


    Fault systems at active plate boundaries accommodate the differential motion of tectonic plates through slip on anastomosing faults within the seismogenic upper crust. The partitioning of slip across fault systems can be inferred from models of space-based geodetic measurements to estimate both fault slip rates and interseismic fault creep. Covariance between slip rate estimates on sub-parallel faults may be significant but can be reduced with the addition of the fundamental constraint that total slip across a fault system must sum to the differential plate motion rate. The importance of ensuring such kinematic consistency becomes increasingly important in strike-slip fault systems such as in the San Francisco Bay Area, where slip is localized across 4-8 sub-parallel faults with San Francisco Bay Area constrained by both GPS and InSAR observations and find that this effect may lead to a substantial revision of interseismic creep estimates on the Hayward fault by as much as 6 mm/yr at depth.

  20. Study on fault locating technology for satellite power system

    Institute of Scientific and Technical Information of China (English)

    LONG Bing; JIANG Xing-wei; SONG Zheng-ji


    It is currently prevalent to locate faults for a satellite power system based on an expert system, not utilizing all the available information provided by tests. The casual network model for a satellite power system is presented. Considerations for failure probability of each component of the power system, the cost of applying each test, the influence of a precedent test result on the next test selection, and an optimal sequential testing algorithm for fault location is presented. This program is applied to locate the failure component of the power system of a satellite. The results show this program is very effective and it is very fast to generate an optimal diagnosis tree.

  1. InSAR observations of strain accumulation and fault creep along the Chaman Fault system, Pakistan and Afghanistan (United States)

    Fattahi, Heresh; Amelung, Falk


    We use 2004-2011 Envisat synthetic aperture radar imagery and InSAR time series methods to estimate the contemporary rates of strain accumulation in the Chaman Fault system in Pakistan and Afghanistan. At 29 N we find long-term slip rates of 16 ± 2.3 mm/yr for the Ghazaband Fault and of 8 ± 3.1 mm/yr for the Chaman Fault. This makes the Ghazaband Fault one of the most hazardous faults of the plate boundary zone. We further identify a 340 km long segment displaying aseismic surface creep along the Chaman Fault, with maximum surface creep rate of 8.1 ± 2 mm/yr. The observation that the Chaman Fault accommodates only 30% of the relative plate motion between India and Eurasia implies that the remainder is accommodated south and east of the Katawaz block microplate.

  2. Shallow to intermediate resistivity features of the Colfiorito Fault System inferred by DC and MT survey

    Directory of Open Access Journals (Sweden)

    A. Siniscalchi


    Full Text Available Over the last decade electromagnetic (EM measurements have provided new constraints on the upper-crustal structure of the major fault zones in the world, both when they act as conduit and as a barrier, due to strong sensitivity of resistivity to fluids circulation and mineralization. On the track of a high impact magnetotelluric (MT study performed across the San Andreas Fault, high resolution EM data were collected in the Colfiorito epicentral area along profiles crossing some main fault lineaments. Being the study focussed both on shallow that on intermediate resistivity distribution in the brittle upper-crust, a MT profile was integrated by several electrical resistivity tomographies (ERT. The latter were successful in locating faults even where the structures are buried by a wide covering of Quaternary deposits and in the recognition of different electrical signatures of the faults. MT resistivity model crossing Mt. Prefoglio normal fault clearly imaged the typical thrust structures of the area and a high conductive zone spatially related to the fault. Seismicity seems to be located outside such conductive area, whose behaviour suggests a fluidised and altered zone incapable of supporting significant stress internally.

  3. Online fault location on crossbonded AC cables in underground transmission systems

    DEFF Research Database (Denmark)

    F. Jensen, Christian; Bak, Claus Leth; Gudmundsdottir, Unnur Stella


    In this paper, a fault locator system specifically designed for crossbonded cables is described. Electromagnetic wave propagation theory for crossbonded cables with focus on fault location purposes is discussed. Based on this, the most optimal modal component and input signal to the fault locator...... system are identified. The fault locator system uses the Wavelet Transform both to create reliable triggers in the units and to estimate the fault location based on time domain signals obtained in the substations by two fault locator units. Field measurements of faults artificially created on a section...... to changes in the fault inception angle, fault resistance and fault location. It is shown that the fault location can be estimated very accurately using the proposed system and the system will be used to monitor Danish crossbonded transmission cables in the future....

  4. Fault Diagnosis and Fault-tolerant Control of Modular Multi-level Converter High-voltage DC System

    DEFF Research Database (Denmark)

    Liu, Hui; Ma, Ke; Wang, Chao


    Modular Multilevel Converter based High Voltage Direct Current (MMC-HVDC) configuration is a promising solution for the efficient grid integration and bulky power transmission over long distance. However, the large number of series connected identical modules in MMC may increase the probability...... strategies of MMC-HVDC systems for the most common faults happened in MMC-HVDC systems covering MMC faults, DC side faults as well as AC side faults. An important part of this paper is devoted to a discussion of the vulnerable spots as well as failure mechanism of the MMC-HVDC system covering switching...

  5. A fault detection and isolation filter for discrete linear systems. (United States)

    Giovanini, L; Dondo, R


    The problem of fault and/or abrupt disturbances detection and isolation for discrete linear systems is analyzed in this work. A strategy for detecting and isolating faults and/or abrupt disturbances is presented. The strategy is an extension of an already existing result in the continuous time domain to the discrete domain. The resulting detection algorithm is a Kalman filter with a special structure. The filter generates a residuals vector in such a way that each element of this vector is related with one fault or disturbance. Therefore the effects of the other faults, disturbances, and measurement noises in this element are minimized. The necessary stability and convergence conditions are briefly exposed. A numerical example is also presented.

  6. Fault tolerance control for proton exchange membrane fuel cell systems (United States)

    Wu, Xiaojuan; Zhou, Boyang


    Fault diagnosis and controller design are two important aspects to improve proton exchange membrane fuel cell (PEMFC) system durability. However, the two tasks are often separately performed. For example, many pressure and voltage controllers have been successfully built. However, these controllers are designed based on the normal operation of PEMFC. When PEMFC faces problems such as flooding or membrane drying, a controller with a specific design must be used. This paper proposes a unique scheme that simultaneously performs fault diagnosis and tolerance control for the PEMFC system. The proposed control strategy consists of a fault diagnosis, a reconfiguration mechanism and adjustable controllers. Using a back-propagation neural network, a model-based fault detection method is employed to detect the PEMFC current fault type (flooding, membrane drying or normal). According to the diagnosis results, the reconfiguration mechanism determines which backup controllers to be selected. Three nonlinear controllers based on feedback linearization approaches are respectively built to adjust the voltage and pressure difference in the case of normal, membrane drying and flooding conditions. The simulation results illustrate that the proposed fault tolerance control strategy can track the voltage and keep the pressure difference at desired levels in faulty conditions.

  7. Fault Tolerant Emergency Control to Preserve Power System Stability

    DEFF Research Database (Denmark)

    Pedersen, Andreas Søndergaard; Richter, Jan H.; Tabatabaeipour, Mojtaba;


    This paper introduces a method for fault-masking and system reconfiguration in power transmission systems. The paper demonstrates how faults are handled by reconfiguring remaining controls through utilisation of wide-area measurement in real time. It is shown how reconfiguration can be obtained...... using a virtual actuator concept, which covers Lure-type systems. The paper shows the steps needed to calculate a virtual actuator, which relies on the solution of a linear matrix inequality. The solution is shown to work with existing controls by adding a compensation signal. Simulation results...... of a benchmark system show ability of the reconfiguration to maintain stability...

  8. Systems and Methods for Determining Inertial Navigation System Faults (United States)

    Bharadwaj, Raj Mohan (Inventor); Bageshwar, Vibhor L. (Inventor); Kim, Kyusung (Inventor)


    An inertial navigation system (INS) includes a primary inertial navigation system (INS) unit configured to receive accelerometer measurements from an accelerometer and angular velocity measurements from a gyroscope. The primary INS unit is further configured to receive global navigation satellite system (GNSS) signals from a GNSS sensor and to determine a first set of kinematic state vectors based on the accelerometer measurements, the angular velocity measurements, and the GNSS signals. The INS further includes a secondary INS unit configured to receive the accelerometer measurements and the angular velocity measurements and to determine a second set of kinematic state vectors of the vehicle based on the accelerometer measurements and the angular velocity measurements. A health management system is configured to compare the first set of kinematic state vectors and the second set of kinematic state vectors to determine faults associated with the accelerometer or the gyroscope based on the comparison.

  9. Fault detection for nonlinear systems - A standard problem approach

    DEFF Research Database (Denmark)

    Stoustrup, Jakob; Niemann, Hans Henrik


    The paper describes a general method for designing (nonlinear) fault detection and isolation (FDI) systems for nonlinear processes. For a rich class of nonlinear systems, a nonlinear FDI system can be designed using convex optimization procedures. The proposed method is a natural extension...

  10. Inter Processor Communication for Fault Diagnosis in Multiprocessor Systems

    Directory of Open Access Journals (Sweden)

    C. D. Malleswar


    Full Text Available In the preseJlt paper a simple technique is proposed for fault diagnosis for multiprocessor and multiple system environments, wherein all microprocessors in the system are used in part to check the health of their neighbouring processors. It involves building simple fail-safe serial communication links between processors. Processors communicate with each other over these links and each processor is made to go through certain sequences of actions intended for diagnosis, under the observation of another processor .With limited overheads, fault detection can be done by this method. Also outlined are some of the popular techniques used for health check of processor-based systems.

  11. Diagnosis and Fault-Tolerant Control for Thruster-Assisted Position Mooring System

    DEFF Research Database (Denmark)

    Nguyen, Trong Dong; Blanke, Mogens; Sørensen, Asgeir


    Development of fault-tolerant control systems is crucial to maintain safe operation of o®shore installations. The objective of this paper is to develop a fault- tolerant control for thruster-assisted position mooring (PM) system with faults occurring in the mooring lines. Faults in line...

  12. Design of fault tolerant control system for steam generator using

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Myung Ki; Seo, Mi Ro [Korea Electric Power Research Institute, Taejon (Korea, Republic of)


    A controller and sensor fault tolerant system for a steam generator is designed with fuzzy logic. A structure of the proposed fault tolerant redundant system is composed of a supervisor and two fuzzy weighting modulators. A supervisor alternatively checks a controller and a sensor induced performances to identify which part, a controller or a sensor, is faulty. In order to analyze controller induced performance both an error and a change in error of the system output are chosen as fuzzy variables. The fuzzy logic for a sensor induced performance uses two variables : a deviation between two sensor outputs and its frequency. Fuzzy weighting modulator generates an output signal compensated for faulty input signal. Simulations show that the proposed fault tolerant control scheme for a steam generator regulates well water level by suppressing fault effect of either controllers or sensors. Therefore through duplicating sensors and controllers with the proposed fault tolerant scheme, both a reliability of a steam generator control and sensor system and that of a power plant increase even more. 2 refs., 9 figs., 1 tab. (Author)

  13. Fault-tolerant Control Systems-An Introductory Overview

    Institute of Scientific and Technical Information of China (English)

    Jin Jiang


    This paper presents an introductory overview on the development of fault-tolerant control systems. For this reason, the paper is written in a tutorial fashion to summarize some of the important results in this subject area deliberately without going into details in any of them. However, key references are provided from which interested readers can obtain more detailed information on a particular subject. It is necessary to mention that, throughout this paper, no efforts were made to provide an exhaustive coverage on the subject matter. In fact, it is far from it. The paper merely represents the view and experience of its author. It can very well be that some important issues or topics were left out unintentionally. If that is the case, the author sincerely apologizes in advance.After a brief account of fault-tolerant control systems, particularly on the original motivations, and the concept of redundancies, the paper reviews the development of fault-tolerant control systems with highlights to several important issues from a historical perspective. The general approaches to fault-tolerant control has been divided into passive, active, and hybrid approaches. The analysis techniques for active fault-tolerant control systems are also discussed. Practical applications of faulttolerant control are highlighted from a practical and industrial perspective. Finally, some critical issues in this area are discussed as open problems for future research/development in this emerging field.

  14. Fault Tolerance Middleware for a Multi-Core System (United States)

    Some, Raphael R.; Springer, Paul L.; Zima, Hans P.; James, Mark; Wagner, David A.


    Fault Tolerance Middleware (FTM) provides a framework to run on a dedicated core of a multi-core system and handles detection of single-event upsets (SEUs), and the responses to those SEUs, occurring in an application running on multiple cores of the processor. This software was written expressly for a multi-core system and can support different kinds of fault strategies, such as introspection, algorithm-based fault tolerance (ABFT), and triple modular redundancy (TMR). It focuses on providing fault tolerance for the application code, and represents the first step in a plan to eventually include fault tolerance in message passing and the FTM itself. In the multi-core system, the FTM resides on a single, dedicated core, separate from the cores used by the application. This is done in order to isolate the FTM from application faults and to allow it to swap out any application core for a substitute. The structure of the FTM consists of an interface to a fault tolerant strategy module, a responder module, a fault manager module, an error factory, and an error mapper that determines the severity of the error. In the present reference implementation, the only fault tolerant strategy implemented is introspection. The introspection code waits for an application node to send an error notification to it. It then uses the error factory to create an error object, and at this time, a severity level is assigned to the error. The introspection code uses its built-in knowledge base to generate a recommended response to the error. Responses might include ignoring the error, logging it, rolling back the application to a previously saved checkpoint, swapping in a new node to replace a bad one, or restarting the application. The original error and recommended response are passed to the top-level fault manager module, which invokes the response. The responder module also notifies the introspection module of the generated response. This provides additional information to the

  15. Node Grouping in System-Level Fault Diagnosis

    Institute of Scientific and Technical Information of China (English)

    ZHANG Dafang; XIE Gaogang; MIN Yinghua


    With the popularization of network applications and multiprocessor systems,dependability of systems has drawn considerable attention. This paper presents a new technique of node grouping for system-level fault diagnosis to simplify the complexity of large system diagnosis. The technique transforms a complicated system to a group network, where each group may consist of many nodes that are either fault-free or faulty. It is proven that the transformation leads to a unique group network to ease system diagnosis. Then it studies systematically one-step t-faults diagnosis problem based on node grouping by means of the concept of independent point sets and gives a simple sufficient and necessary condition. The paper presents a diagnosis procedure for t-diagnosable systems. Furthermore, an efficient probabilistic diagnosis algorithm for practical applications is proposed based on the belief that most of the nodes in a system are fault-free. The result of software simulation shows that the probabilistic diagnosis provides high probability of correct diagnosis and low diagnosis cost, and is suitable for systems of any kind of topology.

  16. A Survey on Fault Tolerant Multi Agent System

    Directory of Open Access Journals (Sweden)

    Yasir Arfat


    Full Text Available A multi-agent system (MAS is formed by a number of agents connected together to achieve the desired goals specified by the design. Usually in a multi agent system, agents work on behalf of a user to accomplish given goals. In MAS co-ordination, co-operation, negotiation and communication are important aspects to achieve fault tolerance in MAS. The multi-agent system is likely to fail in a distributed environment and as an outcome of such, the resources for MAS may not be available due to the failure of an agent, machine crashes, process failure, software failure, communication failure and/or hardware failure. Therefore, many researchers have proposed fault tolerance approaches to overcome the failure in MAS. So we have surveyed these approaches in this paper, whereby our contribution is threefold. Firstly, we have provided taxonomy of faults and techniques in MAS. Secondly, we have provided a qualitative comparison of existing fault tolerance approaches. Thirdly, we have provided an evaluation of existing fault tolerance techniques. Results show that most of the existing schemes are not very efficient, due to various reasons like high computation costs, costly replication and large communication overheads.

  17. Efficient Fault Tree Analysis of Complex Fault Tolerant Multiple-Phased Systems

    Institute of Scientific and Technical Information of China (English)

    MO Yuchang; LIU Hongwei; YANG Xiaozong


    Fault tolerant multiple phased systems (FTMPS), i.e., systems whose critical components are independently replicated and whose operational life can be partitioned in a set of disjoint periods, are called "phases". Because of their deployment in critical applications, their reliability analysis is a task of primary relevance to validate the designs. Fault tree analysis based on binary decision diagram (BDD) is one of the most commonly used techniques for FTMPS reliability analysis. To utilize the technique the fault tree structure of FTMPS needs to be converted into the corresponding BDD format. Our research work shows that the system BDD generation algorithms presented in the literature are too inefficient to be used for industrial complex FTPMS because of the problems, such as variable ordering and combination of large BDDs. This paper presents a more efficient approach consisting of a flatting pre-processing technique, a proved efficient ordering heuristic and a bottom-up generation algorithm. The approach tries to combine share-variable BDDs by complex combination operation firstly and then combine no-share-variable BDDs using simple combination operation, thus to alvoid the intensive computations caused by large BDD combination operations. An example FTMPS is analyzed to illustrate the advantages of our approach.

  18. Estimation of Parametric Fault in Closed-loop Systems

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Poulsen, Niels Kjølstad


    The aim of this paper is to present a method for estimation of parametric faults in closed-loop systems. The key technology applied in this paper is coprime factorization of both the dynamic system as well as the feedback controller. Using the Youla-Jabr-Bongiorno-Kucera (YJBK) parameterization, ...

  19. Rapid transient fault insertion in large digital systems

    NARCIS (Netherlands)

    Rohani, Alireza; Kerkhoff, Hans G.


    This paper presents a technique for rapidtransientfault injection, regarding the CPU time, to perform simulation-based fault-injection in complex System-on-Chip Systems (SoCs). The proposed approach can be applied to complex circuits, as it is not required to modify the top-level modules of a design

  20. How fault zones impact regional permeability and groundwater systems: insights from global database of fault zone studies. (United States)

    Scibek, J.; McKenzie, J. M.; Gleeson, T.


    Regional and continental scale groundwater flow models derive aquifer permeability distributions from datasets based on hydraulic tests and calibrated local and regional flow models, however, much of this data does not account for barrier/conduit effects of fault zones, local and regional geothermal flow cells, and other fault-controlled flow systems. In this study we researched and compiled fault zone permeability and conceptual permeability models in different geologic settings from published multidisciplinary literature (structural- and hydro-geology, engineering geology of tunnels and mines, and geothermal projects among others). The geospatial database focuses on data-rich regions such as North America, Europe, and Japan. Regionalization of the dominant conceptual models of fault zones was regionalized based on geological attributes and tested conceptually with simple numerical models, to help incorporate the effect of fault zones on regional to continental flow models. Results show that for large regional and continental scale flow modeling, the fault zone data can be generalized by geology to determine the relative importance of fault conduits vs fault barriers, which can be converted to effective anisotropy ratios for large scale flow, although local fault-controlled flow cells in rift zones require appropriate upscaling. The barrier/conduit properties of fault zones are present in all regions and rock types, and the barrier effect must be properly conceptualized in large scale flow models. The fault zone data from different geologic disciplines have different biases (e.g. outcrop studies, deep drillhole tests, tunnels, etc.) depending on scale of hydraulic tests. Finally, the calibrated recharge estimates for fault controlled flow systems may be lower than for unfaulted flow systems due to predominant barrier (regional anisotropy or permeability reduction), suggesting a "scaling effect" on recharge estimates.

  1. Active Fault Tolerant Control of Livestock Stable Ventilation System

    DEFF Research Database (Denmark)

    Gholami, Mehdi


    Modern stables and greenhouses are equipped with different components for providing a comfortable climate for animals and plant. A component malfunction may result in loss of production. Therefore, it is desirable to design a control system, which is stable, and is able to provide an acceptable......). In the FTC part of the thesis, first a passive fault tolerant controller (PFTC) based on state feed-back is proposed for discretetime PWA systems. only actuator faults are considered. By dissipativity theory and H1 analysis, the problem is cast as a set of linear matrix inequalities (LMIs). In the next...

  2. Fault Diagnosis in Dynamic Systems Using Fuzzy Interacting Observers

    Directory of Open Access Journals (Sweden)

    N. V. Kolesov


    Full Text Available A method of fault diagnosis in dynamic systems based on a fuzzy approach is proposed. The new method possesses two basic specific features which distinguish it from the other known fuzzy methods based on the application of fuzzy logic and a bank of state observers. First, this method uses a bank of interacting observers instead of traditional independent observers. The second specific feature of the proposed method is the assumption that there is no strict boundary between the serviceable and disabled technical states of the system, which makes it possible to specify a decision making rule for fault diagnosis.

  3. Design a Fault Tolerance for Real Time Distributed System


    Ban M. Khammas


    This paper designed a fault tolerance for soft real time distributed system (FTRTDS). This system is designed to be independently on specific mechanisms and facilities of the underlying real time distributed system. It is designed to be distributed on all the computers in the distributed system and controlled by a central unit.Besides gathering information about a target program spontaneously, it provides information about the target operating system and the target hardware in order to diagno...

  4. Influences of Resistor-Type Superconducting Fault Current Limiter on Power System Transient Stability with Asymmetrical Short-Circuit Faults

    Institute of Scientific and Technical Information of China (English)

    Xue-Ping Gu; Zhi-Long Yang


    The transient stability of a single machine to infinite-busbar power system with resistor- type superconducting fault current limiters (SFCL) is analyzed under asymmetrical short-circuit fault conditions. The SFCL is considered to introduce a resistance into the three-phase circuits when faults occur. Based on the power-angle curves for different short-circuit conditions of the single-line to ground, double-line to ground and line to line short-circuit faults, the influences of the SFCLs on transient stability are analyzed in detail. The time-domain simulation of transient stability is carried out to verify the analytical results.

  5. Managing systems faults on the commercial flight deck: Analysis of pilots' organization and prioritization of fault management information (United States)

    Rogers, William H.


    In rare instances, flight crews of commercial aircraft must manage complex systems faults in addition to all their normal flight tasks. Pilot errors in fault management have been attributed, at least in part, to an incomplete or inaccurate awareness of the fault situation. The current study is part of a program aimed at assuring that the types of information potentially available from an intelligent fault management aiding concept developed at NASA Langley called 'Faultfinde' (see Abbott, Schutte, Palmer, and Ricks, 1987) are an asset rather than a liability: additional information should improve pilot performance and aircraft safety, but it should not confuse, distract, overload, mislead, or generally exacerbate already difficult circumstances.

  6. Chaos Synchronization Based Novel Real-Time Intelligent Fault Diagnosis for Photovoltaic Systems

    Directory of Open Access Journals (Sweden)

    Chin-Tsung Hsieh


    Full Text Available The traditional solar photovoltaic fault diagnosis system needs two to three sets of sensing elements to capture fault signals as fault features and many fault diagnosis methods cannot be applied with real time. The fault diagnosis method proposed in this study needs only one set of sensing elements to intercept the fault features of the system, which can be real-time-diagnosed by creating the fault data of only one set of sensors. The aforesaid two points reduce the cost and fault diagnosis time. It can improve the construction of the huge database. This study used Matlab to simulate the faults in the solar photovoltaic system. The maximum power point tracker (MPPT is used to keep a stable power supply to the system when the system has faults. The characteristic signal of system fault voltage is captured and recorded, and the dynamic error of the fault voltage signal is extracted by chaos synchronization. Then, the extension engineering is used to implement the fault diagnosis. Finally, the overall fault diagnosis system only needs to capture the voltage signal of the solar photovoltaic system, and the fault type can be diagnosed instantly.

  7. [Andreas Vesalius and surgery]. (United States)

    Van Hee, R


    By publishing De Humani Corporis Fabrica Libri Septem in 1543, Andries van Wesel (1514-1564) gave surgical science an immense impulse. The revolutionary renovation in the knowledge of man's anatomical structure changed slowly and progressively into topographical and physiological understanding of surgical diseases. At the same time, this made better aimed and more secure operations possible. Apart from the importance of this anatomical publication, Andreas Vesalius also won his spurs as a surgeon. He taught surgery in Padua for many years. He was appointed court physician and surgeon at the Habsburg Court of Charles V and Philip II. He personally performed lots of operations known at the time as major ones. He not only quickly adopted the surgical innovations of his fellow-surgeon Ambroise Paré, but he even performed operations that had been forgotten during several centuries, among which thoracocentesis for pleural empyema. His clinical perspicacity in discovering the indication for some operations was staggering and was appreciated by all great monarchs of Europe in the 16th century. In his several consilia, numerous pieces of advice were given for the treatment of surgical patients. The surgical practice which Vesalius had in Brussels for many years, consequently became most successful. Many publications by Vesalius about surgery and blood-letting are well-known. His Chirurgia magna in septem Libros digesta still remains controversial; these books were published by Prospero Borgarruccio (1560) in 1568 by the Venetian editor Valgrisi. This book gives an excellent survey of surgical pathology as it was taught and treated in the 16th century. The scientific method that Vesalius used, not only in his anatomical studies but also in his surgical practice, deserves not only our full appraisal but should still be studied in our own time.


    Institute of Scientific and Technical Information of China (English)

    Han Yilun


    Fault diagnosis expert system for hydraulic support is studied.The system is achieved by Turbo-prolong Language, it summaries the experience of the domain expert and sets up a fault tree, knowledge base is developed by a productive rule.According to the feature of diagnosis, the system selects forward non-determination inferring and limited depth-first search strategy.It can accomplish expert diagnosis of more than 50 kinds faults in hydraulic support.

  9. Rapid Post-Miocene tectonic rotation associated with the San Gregorio Fault Zone in central California (United States)

    Holm, Eric J.; Horns, Daniel M.; Verosub, Kenneth L.


    Paleomagnetic measurements of samples from the Mio-Pliocene Purisima Formation demonstrate that the Pomponio tectonic block of central coastal California has rotated clockwise by approximately 35° to 55° within the last 2.5 million years. The most likely interpretation of this data is that the Pomponio block is broken into several small blocks which have rotated by various amounts. The data suggest that rotations contribute to vertical deformation and secondary faulting within the central San Andreas Fault System, and that they play an important role in the accommodation of shear along the fault system.

  10. Fault-diagnosis applications. Model-based condition monitoring. Acutators, drives, machinery, plants, sensors, and fault-tolerant systems

    Energy Technology Data Exchange (ETDEWEB)

    Isermann, Rolf [Technische Univ. Darmstadt (DE). Inst. fuer Automatisierungstechnik (IAT)


    Supervision, condition-monitoring, fault detection, fault diagnosis and fault management play an increasing role for technical processes and vehicles in order to improve reliability, availability, maintenance and lifetime. For safety-related processes fault-tolerant systems with redundancy are required in order to reach comprehensive system integrity. This book is a sequel of the book ''Fault-Diagnosis Systems'' published in 2006, where the basic methods were described. After a short introduction into fault-detection and fault-diagnosis methods the book shows how these methods can be applied for a selection of 20 real technical components and processes as examples, such as: Electrical drives (DC, AC) Electrical actuators Fluidic actuators (hydraulic, pneumatic) Centrifugal and reciprocating pumps Pipelines (leak detection) Industrial robots Machine tools (main and feed drive, drilling, milling, grinding) Heat exchangers Also realized fault-tolerant systems for electrical drives, actuators and sensors are presented. The book describes why and how the various signal-model-based and process-model-based methods were applied and which experimental results could be achieved. In several cases a combination of different methods was most successful. The book is dedicated to graduate students of electrical, mechanical, chemical engineering and computer science and for engineers. (orig.)

  11. Fault tolerance techniques for embedded telemetry system: case study (United States)

    Krosman, Kazimierz; Sosnowski, Janusz


    This paper presents software methods of improving fault tolerance in embedded systems. These methods have been adapted to a telemetry system dedicated to tracking vehicles for logistics purposes. The developed telemetry system allows us to monitor vehicle position and some technical parameters via GSM communication. It comprises the capability of remote software reconfiguration. To evaluate dependability of the system we use a fault injection technique based on simulating bit-flip errors within memory cells. For this purpose an original testbed has been developed. It provides not only the capability of disturbing internal state of the tested system (via JTAG interface) but also the possibility of controlling system input states and observing its behavior (in particular output signals) according to specified test scenarios. The whole test process is automatized. The paper presents a case study related to a commercial product but the described methodology and techniques can be extended for other embedded systems.

  12. Fault-tolerant clock synchronization validation methodology. [in computer systems (United States)

    Butler, Ricky W.; Palumbo, Daniel L.; Johnson, Sally C.


    A validation method for the synchronization subsystem of a fault-tolerant computer system is presented. The high reliability requirement of flight-crucial systems precludes the use of most traditional validation methods. The method presented utilizes formal design proof to uncover design and coding errors and experimentation to validate the assumptions of the design proof. The experimental method is described and illustrated by validating the clock synchronization system of the Software Implemented Fault Tolerance computer. The design proof of the algorithm includes a theorem that defines the maximum skew between any two nonfaulty clocks in the system in terms of specific system parameters. Most of these parameters are deterministic. One crucial parameter is the upper bound on the clock read error, which is stochastic. The probability that this upper bound is exceeded is calculated from data obtained by the measurement of system parameters. This probability is then included in a detailed reliability analysis of the system.

  13. Four-Dimensional Transform Fault Processes: Evolution of Step-Overs and Bends at Different Scales (United States)

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


    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

  14. Inferences drawn from two decades of alinement array measurements of creep on faults in the San Francisco Bay Region (United States)

    Galehouse, J.S.; Lienkaemper, J.J.


    We summarize over 20 years of monitoring surface creep on faults of the San Andreas system in the San Francisco Bay region using alinement arrays. The San Andreas fault is fully locked at five sites northwest from San Juan Bautista, the southern end of the 1906 earthquake rupture, that is, no creep (San Gregorio, Rodgers Creek, and West Napa faults show no creep. The measured creep rate on the Calaveras-Paicines fault from Hollister southward is either 6 or ??? 10 mm/yr, depending on whether the arrays cross all of the creeping traces. Northward of Hollister, the central Calaveras creep rate reaches 14 ?? 2 mm/yr but drops to ??? 2 mm/yr near Calaveras Reservoir, where slip transfers to the southern Hayward fault at a maximum creep rate of 9 mm/yr at its south end. However, the Hayward fault averages only 4.6 mm/yr over most of its length. The Northern Calaveras fault, now creeping at 3-4 mm/yr, steps right to the Concord fault, which has a similar rate, 2.5-3.5 mm/yr, which is slightly slower than the 4.4 mm/yr rate on its northward continuation, the Green Valley fault. The Maacama fault creeps at 4.4 mm/yr near Ukiah and 6.5 mm/yr in Willits. The central and southern segments of the Calaveras fault are predominantly creeping, whereas the Hayward, Northern Calaveras, and Maacama faults are partly locked and, along with the Rodgers Creek and San Andreas, have high potential for major earthquakes.

  15. Wiring systems and fault finding for installation electricians

    CERN Document Server

    Scaddan, Brian


    This book deals with an area of practice that many students and non-electricians find particularly challenging. It explains how to interpret circuit diagrams, wiring systems, and outlines the principles of testing before explaining how to apply this knowledge to fault finding in electrical circuits. A handy pocket guide for anybody that needs to be able to trace faults in circuits, whether in domestic, commercial or industrial settings, this book will be extremely useful to electricians, plumbers, heating engineers and intruder alarm installers.

  16. Vibration Signature Analysis of a Faulted Gear Transmission System (United States)

    Choy, F. K.; Huang, S.; Zakrajsek, J. J.; Handschuh, R. F.; Townsend, D. P.


    A comprehensive procedure in predicting faults in gear transmission systems under normal operating conditions is presented. Experimental data were obtained from a spiral bevel gear fatigue test rig at NASA/Lewis. Time-synchronous-averaged vibration data were recorded throughout the test as the fault progressed from a small single pit to severe pitting over several teeth, and finally tooth fracture. A numerical procedure based on the Wigner-Ville distribution was used to examine the time-averaged vibration data. Results from the Wigner-Ville procedure are compared to results from a variety of signal analysis techniques that include time-domain analysis methods and frequency analysis methods. Using photographs of the gear tooth at various stages of damage, the limitations and accuracy of the various techniques are compared and discussed. Conclusions are drawn from the comparison of the different approaches as well as the applicability of the Wigner-Ville method in predicting gear faults.

  17. Similarity measure application to fault detection of flight system

    Institute of Scientific and Technical Information of China (English)

    KIM J H; LEE S H; WANG Hong-mei


    Fault detection technique is introduced with similarity measure. The characteristics of conventional similarity measure based on fuzzy number are discussed. With the help of distance measure, similarity measure is constructed explicitly. The designed distance-based similarity measure is applicable to general fuzzy membership functions including non-convex fuzzy membership function, whereas fuzzy number-based similarity measure has limitation to calculate the similarity of general fuzzy membership functions. The applicability of the proposed similarity measure to general fuzzy membership structures is proven by identifying the definition. To decide fault detection of flight system, the experimental data (pitching moment coefficients and lift coefficients) are transformed into fuzzy membership functions. Distance-based similarity measure is applied to the obtained fuzzy membership functions, and similarity computation and analysis are obtained with the fault and normal operation coefficients.

  18. Spacing and strength of active continental strike-slip faults (United States)

    Zuza, Andrew V.; Yin, An; Lin, Jessica; Sun, Ming


    Parallel and evenly-spaced active strike-slip faults occur widely in nature across diverse tectonic settings. Despite their common existence, the fundamental question of what controls fault spacing remains unanswered. Here we present a mechanical model for the generation of parallel strike-slip faults that relates fault spacing to the following parameters: (1) brittle-crust thickness, (2) fault strength, (3) crustal strength, and (4) crustal stress state. Scaled analogue experiments using dry sand, dry crushed walnut shells, and viscous putty were employed to test the key assumptions of our quantitative model. The physical models demonstrate that fault spacing (S) is linearly proportional to brittle-layer thickness (h), both in experiments with only brittle materials and in two-layer trials involving dry sand overlying viscous putty. The S / h slope in the two-layer sand-putty experiments may be controlled by the (1) rheological/geometric properties of the viscous layer, (2) effects of distributed basal loading caused by the viscous shear of the putty layer, and/or (3) frictional interaction at the sand-putty interface (i.e., coupling between the viscous and brittle layers). We tentatively suggest that this third effect exerts the strongest control on fault spacing in the analogue experiments. By applying our quantitative model to crustal-scale strike-slip faults using fault spacing and the seismogenic-zone thickness obtained from high-resolution earthquake-location data, we estimate absolute fault friction of active strike-slip faults in Asia and along the San Andreas fault system in California. We show that the average friction coefficient of strike-slip faults in the India-Asia collisional orogen is lower than that of faults in the San Andreas fault system. Weaker faults explain why deformation penetrates >3500 km into Asia from the Himalaya and why the interior of Asia is prone to large (M > 7.0) devastating earthquakes along major intra-continental strike

  19. A Ship Propulsion System Model for Fault-tolerant Control

    DEFF Research Database (Denmark)

    Izadi-Zamanabadi, Roozbeh; Blanke, M.

    This report presents a propulsion system model for a low speed marine vehicle, which can be used as a test benchmark for Fault-Tolerant Control purposes. The benchmark serves the purpose of offering realistic and challenging problems relevant in both FDI and (autonomous) supervisory control area....

  20. Automated Fault Localization for Service-Oriented Software Systems

    NARCIS (Netherlands)

    Chen, C.


    In this thesis, we have focused on applying Spectrum-based Fault Localization (SFL) to diagnose Service-Oriented Systems at runtime. We reused a framework-based online monitoring technique to obtain the service transaction information. We devised a three-phased oracle and combined this with monitori

  1. Sequential fault diagnosis for mechatronics system using diagnostic hybrid bond graph and composite harmony search

    Directory of Open Access Journals (Sweden)

    Ming Yu


    Full Text Available This article proposes a sequential fault diagnosis method to handle asynchronous distinct faults using diagnostic hybrid bond graph and composite harmony search. The faults under consideration include fault mode, abrupt fault, and intermittent fault. The faults can occur in different time instances, which add to the difficulty of decision making for fault diagnosis. This is because the earlier occurred fault can exhibit fault symptom which masks the fault symptom of latter occurred fault. In order to solve this problem, a sequential identification algorithm is developed in which the identification task is reactivated based on two conditions. The first condition is that the latter occurred fault has at least one inconsistent coherence vector element which is consistent in coherence vector of the earlier occurred fault, and the second condition is that the existing fault coherence vector has the ability to hide other faults and the second-level residual exceeds the threshold. A new composite harmony search which is capable of handling continuous variables and binary variables simultaneously is proposed for identification purpose. Experiments on a mobile robot system are conducted to assess the proposed sequential fault diagnosis algorithm.

  2. A Fault-based Crustal Deformation Model for UCERF3 and Its Implication to Seismic Hazard Analysis (United States)

    Zeng, Y.; Shen, Z.


    We invert GPS data to determine slip rates on major California faults using a fault-based crustal deformation model with geological slip rate constraints. The model assumes buried elastic dislocations across the region using fault geometries defined by the Uniform California Earthquake Rupture Forecast version 3 (UCERF3) project with fault segments slipping beneath their locking depths. GPS observations across California and neighboring states were obtained from the UNAVCO western US GPS velocity model and edited by the SCEC UCERF3 geodetic deformation working group. The geologic slip rates and fault style constraints were compiled by the SCEC UCERF3 geologic deformation working group. Continuity constraints are imposed on slips among adjacent fault segments to regulate slip variability and to simulate block-like motion. Our least-squares inversion shows that slip rates along the northern San Andreas fault system agree well with the geologic estimates provided by UCERF3, and slip rates for the Calaveras-Hayward-Maacama fault branch and the Greenville-Great Valley fault branch are slightly higher than that of the UCERF3 geologic model. The total slip rates across transects of the three fault branches in Northern California amount to 39 mm/yr. Slip rates determined for the Garlock fault closely match geologic rates. Slip rates for the Coachella Valley and Brawley segment of the San Andreas are nearly twice that of the San Jacinto fault branch. For the off-coast faults along the San Gregorio, Hosgri, Catalina, and San Clemente faults, slip rates are near their geologic lower bounds. Comparing with the regional geologic slip rate estimates, the GPS based model shows a significant decrease of 6-14 mm/yr in slip rates along the San Andreas fault system from the central California creeping section through the Mojave to the San Bernardino Mountain segments, whereas the model indicates significant increase of 1-3 mm/yr in slip-rates for faults along the east California

  3. Sensor Fault Estimation Filter Design for Discrete-time Linear Time-varying Systems

    Institute of Scientific and Technical Information of China (English)

    WANG Zhen-Hua; RODRIGUES Mickael; THEILLIOL Didier; SHEN Yi


    This paper proposes a sensor fault diagnosis method for a class of discrete-time linear time-varying (LTV) systems. In this paper, the considered system is firstly formulated as a de-scriptor system representation by considering the sensor faults as auxiliary state variables. Based on the descriptor system model, a fault estimation filter which can simultaneously estimate the state and the sensor fault magnitudes is designed via a minimum-variance principle. Then, a fault diagnosis scheme is presented by using a bank of the proposed fault estimation filters. The novelty of this paper lies in developing a sensor fault diagnosis method for discrete LTV systems without any assumption on the dynamic of fault. Another advantage of the proposed method is its ability to detect, isolate and estimate sensor faults in the presence of process noise and measurement noise. Simulation results are given to illustrate the effectiveness of the proposed method.

  4. Andreas Struppleri intelligentsed rakendused / Andreas Struppler ; interv. Margit Aedla

    Index Scriptorium Estoniae

    Struppler, Andreas


    Disainer Andreas Struppler (sünd. 1964) enda ja oma meeskonna loodud e-mood'i sarja vannitoast, valgustusest vannitoas. Privaatala eraldamiseks ülejäänud vannitoast suunatakse värviline valgus keraamiliselt trükitud klaaspaneelile. E-sirm on ruumijagaja moodne tõlgendus

  5. Design and implementation of an expert system for remote fault diagnosis in ship lift

    Institute of Scientific and Technical Information of China (English)


    In this paper an expert system for remote fault diagnosis in the ship lift was developed by analysis of the fault tree and combination with VPN. The fault tree was constructed based on the operation condition of the ship lift. The diagnosis model was constructed by hierarchical classification of the fault tree structure, and the inference mechanism was given. Logical structure of the fault diagnosis in the ship lift was proposed. The implementation of the expert system for remote fault diagnosis in the ship lift was discussed, and the expert system developed was realized on the VPN virtual network. The system was applied to the Gaobaozhou ship lift project, and it ran successfully.

  6. Fault Diagnosis for Actuators in a Class of Nonlinear Systems Based on an Adaptive Fault Detection Observer

    Directory of Open Access Journals (Sweden)

    Runxia Guo


    Full Text Available The problem of actuators’ fault diagnosis is pursued for a class of nonlinear control systems that are affected by bounded measurement noise and external disturbances. A novel fault diagnosis algorithm has been proposed by combining the idea of adaptive control theory and the approach of fault detection observer. The asymptotical stability of the fault detection observer is guaranteed by setting the adaptive adjusting law of the unknown fault vector. A theoretically rigorous proof of asymptotical stability has been given. Under the condition that random measurement noise generated by the sensors of control systems and external disturbances exist simultaneously, the designed fault diagnosis algorithm is able to successfully give specific estimated values of state variables and failures rather than just giving a simple fault warning. Moreover, the proposed algorithm is very simple and concise and is easy to be applied to practical engineering. Numerical experiments are carried out to evaluate the performance of the fault diagnosis algorithm. Experimental results show that the proposed diagnostic strategy has a satisfactory estimation effect.

  7. Calculation of critical fault recovery time for nonlinear systems based on region of attraction analysis

    DEFF Research Database (Denmark)

    Tabatabaeipour, Mojtaba; Blanke, Mogens


    of a system. It must be guaranteed that the trajectory of a system subject to fault remains in the region of attraction (ROA) of the post-fault system during this time. This paper proposes a new algorithm to compute the critical fault recovery time for nonlinear systems with polynomial vector elds using sum...

  8. InSAR time-series constraints on inter-seismic strain accumulation and creep distribution along North Anatolian and Chaman Faults (United States)

    Havazli, E.; Fattahi, H.; Amelung, F.


    In many aspects, the San Andreas and the North Anatolian fault zones show many similarities. They are similarly right-lateral, strike-slip faults, at the same time, are transforms. However, they vary in the maximum amount of lateral displacement and show different topographic features. The maximum offset is nearly 300 km along the San Andreas Fault whereas it is approximately 85-90 km along the North Anatolian Fault. In recent years, interseismic crustal velocities and strains have been determined for North Anatolian Fault Zone through repeated measurements using the Global Positioning System and satellite radar interferometry. The Chaman Fault in Pakistan and Afghanistan is the only major fault along the western India-Eurasia plate boundary zone and probably accommodates the entire relative plate motion of 30-35 mm/yr. Recent GPS and InSAR studies on the Chaman fault yield slip rates of 18 × 1 mm/yr. The inconsistency in geologic, geodetic and seismic slip rates along the Chaman Fault need investigations to better understand the geodynamic responses of the Indo-Asia collision along its western boundary. We use InSAR time-series analysis using archived and new SAR imagery to constrain strain accumulation across the North Anatolian Fault and Chaman Faults. We expect a relative accuracy of InSAR measurements better than 1 mm/yr over 100 km, made possible by recent advances in flattening residual, orbital error and atmospheric correction strategies [Fattahi & Amelung, 2013]. After validation of the technique in Southern San Andreas Fault, using GPS observations, we apply the same InSAR time-series approach to constrain strain accumulation across the North Anatolian and Chaman Faults. We will use the InSAR data to establish the first-order fault properties of the Chaman and North Anatolian Faults (creep distribution, locking depth) using analytical two-dimensional elastic strain accumulation models along different transects across the faults. Our preliminary results

  9. Ship Propulsion System as a Benchmark for Fault-Tolerant Control


    Izadi-Zamanabadi, Roozbeh; Blanke, M.


    Fault-tolerant control combines fault detection and isolation techniques with supervisory control to achieve autonomous accommodation of faults before they develop into failures. While fault detection and isolation (FDI) methods have matured during the past decade the extension to fault-tolerant control is a fairly new area. The paper presents a ship propulsion system as a benchmark that should be useful as a platform for development of new ideas and comparison of methods. The benchmark has t...

  10. A Solid-State Fault Current Limiting Device for VSC-HVDC Systems (United States)

    Larruskain, D. Marene; Zamora, Inmaculada; Abarrategui, , Oihane; Iturregi, Araitz


    Faults in the DC circuit constitute one of the main limitations of voltage source converter VSC-HVDC systems, as the high fault currents can damage seriously the converters. In this article, a new design for a fault current limiter (FCL) is proposed, which is capable of limiting the fault current as well as interrupting it, isolating the DC grid. The operation of the proposed FCL is analysed and verified with the most usual faults that can occur in overhead lines.

  11. Methods for Fault Diagnosability Analysis of a Class of Affine Nonlinear Systems

    Directory of Open Access Journals (Sweden)

    Xiafu Peng


    Full Text Available The fault diagnosability analysis for a given model, before developing a diagnosis algorithm, can be used to answer questions like “can the fault fi be detected by observed states?” and “can it separate fault fi from fault fj by observed states?” If not, we should redesign the sensor placement. This paper deals with the problem of the evaluation of detectability and separability for the diagnosability analysis of affine nonlinear system. First, we used differential geometry theory to analyze the nonlinear system and proposed new detectability criterion and separability criterion. Second, the related matrix between the faults and outputs of the system and the fault separable matrix are designed for quantitative fault diagnosability calculation and fault separability calculation, respectively. Finally, we illustrate our approach to exemplify how to analyze diagnosability by a certain nonlinear system example, and the experiment results indicate the effectiveness of the fault evaluation methods.

  12. Clay Mineralogy, Authigenic Smectite Concentration, and Fault Weakening of the San Gregorio Fault; Moss Beach, California (United States)

    Mazzoni, S.; Moore, J.; Bish, D. L.


    The apparently weak nature of the San Andreas fault system poses a fundamental geophysical question. The San Gregorio fault at Moss Beach, CA is an active splay of the right-lateral San Andreas fault zone and has a total offset of about 150 km. At Moss Beach, the San Gregorio fault offsets Pliocene sedimentary rocks and consists of a clay-rich gouge zone, eastern sandstone block, and western mudstone block. In the presence of fluids, smectite clays can swell and become very weak to shearing. We studied a profile of samples across the fault zone and wall rocks to determine if there is a concentration of smectite in the gouge zone and propose a possible formation mechanism. Samples were analyzed using standard quantitative X-ray diffraction methods and software recently developed at Los Alamos National Lab. XRD results show a high smectite/illite (weak clay/strong clay) ratio in the gouge (S/I ratio=2-4), lower in the mudstone (S/I ratio=2), and very low in the sandstone (S/I ratio=1). The variability of smectite/illite ratio in the gouge zone may be evidence of preferential alteration where developed shear planes undergo progressive smectite enrichment. The amount of illite layers in illite/smectites is 5-30%, indicating little illitization; therefore, these fault rocks have not undergone significant diagenesis above 100 degrees C and illite present must be largely detrital. Bulk mineralogy shows significant anti-correlation of smectite with feldspar, especially in the gouge, suggesting authigenic smectite generation from feldspar. Under scanning-electron microscope inspection, smectites have fibrous, grain coating growth fabrics, also suggesting smectite authigenesis. If in situ production of smectite via chemical alteration is possible in active faults, it could have significant implications for self-generated weakening of faults above the smectite-to-illite transition (<150 degrees C, or 5-7km).

  13. Fuzzy Concurrent Object Oriented Expert System for Fault Diagnosis in 8085 Microprocessor Based System Board

    Directory of Open Access Journals (Sweden)

    Mr.D. V. Kodavade


    Full Text Available With the acceptance of artificial intelligence paradigm, a number of successful artificial intelligence systems were created. Fault diagnosis in microprocessor based boards needs lot of empirical knowledge and expertise and is a true artificial intelligence problem. Research on fault diagnosis in microprocessor based system boards using new fuzzy-object oriented approach is presented in this paper. There are many uncertain situations observed during fault diagnosis. These uncertain situations were handled using fuzzy mathematics properties. Fuzzy inference mechanism is demonstrated using one case study. Some typical faults in 8085 microprocessor board and diagnostic procedures used is presented in this paper.

  14. Pärnograafiline / Andreas Trossek

    Index Scriptorium Estoniae

    Trossek, Andreas, 1980-


    Priit Pärna näitus Kumu Kunstimuuseumis kuni 21. X. Kuraator Eha Komissarov. 11. V toimus Kumu auditooriumis Priit Pärna loomingule pühendatud rahvusvaheline seminar, peaesinejaks oli Edwin Carels Belgiast. Esitamisele tuli filmiprogramm Priit Pärna filmidest ning toimus ümarlaud, milles osalesid Andreas Trossek, Mari Laaniste ja Priit Pärn

  15. Doubly Fed Induction Generator Wind Turbine Systems Subject to Recurring Symmetrical Grid Faults

    DEFF Research Database (Denmark)

    Chen, Wenjie; Blaabjerg, Frede; Zhu, Nan


    grid faults is established. The analysis is based on the DFIG wind turbine system with the typical low-voltage ride-through strategy-with rotor-side crowbar. The stator natural flux produced by the voltage recovery after the first grid fault may be superposed on the stator natural flux produced......New grid codes demand the wind turbine systems to ride through recurring grid faults. In this paper, the performance of the doubly Ffed induction generator (DFIG) wind turbine system under recurring symmetrical grid faults is analyzed. The mathematical model of the DFIG under recurring symmetrical...... by the second grid fault, so that the transient rotor and stator current and torque fluctuations under the second grid fault may be influenced by the characteristic of the first grid fault, including the voltage dips level and the grid fault angle, as well as the duration between two faults. The mathematical...

  16. A Fault Diagnosis Method of Power Systems Based on Gray System Theory

    Directory of Open Access Journals (Sweden)

    Huang Darong


    Full Text Available To provide some decision-making suggestions for fault diagnosis in power systems, a new model for identifying fault component is constructed by using Gray theory. Firstly, the basic concepts of Gray theory are introduced and explained in detail. And then the recognition algorithm of the power supply interrupted districts and the assignment principle of fault state vectors are depicted according to the working principle of protective relays (PRs and circuit breakers (CBs. Secondly, based on the concept of the Gray correlation degree, the fault information explanation degree model is constructed and the judging method of malfunction and rejection for PRs and CBs is established. Meanwhile, to achieve the goal of the fault diagnosis, the fault diagnosis procedure that determined which components malfunction is designed for power systems. Finally, some simple experiments have already verified that the proposed method and model are effective and reasonable and the trend of further research is analyzed and summarized.

  17. Fault recovery for real-time, multi-tasking computer system (United States)

    Hess, Richard (Inventor); Kelly, Gerald B. (Inventor); Rogers, Randy (Inventor); Stange, Kent A. (Inventor)


    System and methods for providing a recoverable real time multi-tasking computer system are disclosed. In one embodiment, a system comprises a real time computing environment, wherein the real time computing environment is adapted to execute one or more applications and wherein each application is time and space partitioned. The system further comprises a fault detection system adapted to detect one or more faults affecting the real time computing environment and a fault recovery system, wherein upon the detection of a fault the fault recovery system is adapted to restore a backup set of state variables.

  18. The SCEC 3D Community Fault Model (CFM-v5): An updated and expanded fault set of oblique crustal deformation and complex fault interaction for southern California (United States)

    Nicholson, C.; Plesch, A.; Sorlien, C. C.; Shaw, J. H.; Hauksson, E.


    Southern California represents an ideal natural laboratory to investigate oblique deformation in 3D owing to its comprehensive datasets, complex tectonic history, evolving components of oblique slip, and continued crustal rotations about horizontal and vertical axes. As the SCEC Community Fault Model (CFM) aims to accurately reflect this 3D deformation, we present the results of an extensive update to the model by using primarily detailed fault trace, seismic reflection, relocated hypocenter and focal mechanism nodal plane data to generate improved, more realistic digital 3D fault surfaces. The results document a wide variety of oblique strain accommodation, including various aspects of strain partitioning and fault-related folding, sets of both high-angle and low-angle faults that mutually interact, significant non-planar, multi-stranded faults with variable dip along strike and with depth, and active mid-crustal detachments. In places, closely-spaced fault strands or fault systems can remain surprisingly subparallel to seismogenic depths, while in other areas, major strike-slip to oblique-slip faults can merge, such as the S-dipping Arroyo Parida-Mission Ridge and Santa Ynez faults with the N-dipping North Channel-Pitas Point-Red Mountain fault system, or diverge with depth. Examples of the latter include the steep-to-west-dipping Laguna Salada-Indiviso faults with the steep-to-east-dipping Sierra Cucapah faults, and the steep southern San Andreas fault with the adjacent NE-dipping Mecca Hills-Hidden Springs fault system. In addition, overprinting by steep predominantly strike-slip faulting can segment which parts of intersecting inherited low-angle faults are reactivated, or result in mutual cross-cutting relationships. The updated CFM 3D fault surfaces thus help characterize a more complex pattern of fault interactions at depth between various fault sets and linked fault systems, and a more complex fault geometry than typically inferred or expected from

  19. Advanced monitoring, fault diagnostics, and maintenance of cryogenic systems

    CERN Document Server

    Girone, Mario; Pezzetti, Marco

    In this Thesis, advanced methods and techniques of monitoring, fault diagnostics, and predictive maintenance for cryogenic processes and systems are described. In particular, in Chapter 1, mainstreams in research on measurement systems for cryogenic processes are reviewed with the aim of dening key current trends and possible future evolutions. Then, in Chapter 2, several innovative methods are proposed. A transducer based on a virtual ow meter is presented for monitoring helium distribution and consumption in cryogenic systems for particle accelerators [1]. Furthermore, a comprehensive metrological analysis of the proposed transducer for verifying the metrological performance and pointing out most critical uncertainty sources is described [2]. A model-based method for fault detection and early-stage isolation, able to work with few records of Frequency Response Function (FRF) on an unfaulty compressor, is then proposed [3]. To enrich the proposal, a distributed diagnostic procedure, based on a micro-genetic...

  20. The Trans-Rocky Mountain Fault System - A Fundamental Precambrian Strike-Slip System (United States)

    Sims, P.K.


    Recognition of a major Precambrian continental-scale, two-stage conjugate strike-slip fault system - here designated as the Trans-Rocky Mountain fault system - provides new insights into the architecture of the North American continent. The fault system consists chiefly of steep linear to curvilinear, en echelon, braided and branching ductile-brittle shears and faults, and local coeval en echelon folds of northwest strike, that cut indiscriminately across both Proterozoic and Archean cratonic elements. The fault system formed during late stages of two distinct tectonic episodes: Neoarchean and Paleoproterozoic orogenies at about 2.70 and 1.70 billion years (Ga). In the Archean Superior province, the fault system formed (about 2.70-2.65 Ga) during a late stage of the main deformation that involved oblique shortening (dextral transpression) across the region and progressed from crystal-plastic to ductile-brittle deformation. In Paleoproterozoic terranes, the fault system formed about 1.70 Ga, shortly following amalgamation of Paleoproterozoic and Archean terranes and the main Paleoproterozoic plastic-fabric-producing events in the protocontinent, chiefly during sinistral transpression. The postulated driving force for the fault system is subcontinental mantle deformation, the bottom-driven deformation of previous investigators. This model, based on seismic anisotropy, invokes mechanical coupling and subsequent shear between the lithosphere and the asthenosphere such that a major driving force for plate motion is deep-mantle flow.

  1. Fault tolerant aggregation for power system services

    DEFF Research Database (Denmark)

    Kosek, Anna Magdalena; Gehrke, Oliver; Kullmann, Daniel


    Exploiting the flexibility in distributed energy resources (DER) is seen as an important contribution to allow high penetrations of renewable generation in electrical power systems. However, the present control infrastructure in power systems is not well suited for the integration of a very large...... number of small units. A common approach is to aggregate a portfolio of such units together and expose them to the power system as a single large virtual unit. In order to realize the vision of a Smart Grid, concepts for flexible, resilient and reliable aggregation infrastructures are required...

  2. Automatic fault detection on BIPV systems without solar irradiation data

    CERN Document Server

    Leloux, Jonathan; Luna, Alberto; Desportes, Adrien


    BIPV systems are small PV generation units spread out over the territory, and whose characteristics are very diverse. This makes difficult a cost-effective procedure for monitoring, fault detection, performance analyses, operation and maintenance. As a result, many problems affecting BIPV systems go undetected. In order to carry out effective automatic fault detection procedures, we need a performance indicator that is reliable and that can be applied on many PV systems at a very low cost. The existing approaches for analyzing the performance of PV systems are often based on the Performance Ratio (PR), whose accuracy depends on good solar irradiation data, which in turn can be very difficult to obtain or cost-prohibitive for the BIPV owner. We present an alternative fault detection procedure based on a performance indicator that can be constructed on the sole basis of the energy production data measured at the BIPV systems. This procedure does not require the input of operating conditions data, such as solar ...

  3. Robust and Active Fault-tolerant Control for a Class of Nonlinear Uncertain Systems

    Institute of Scientific and Technical Information of China (English)

    You-Qing Wang; Dong-Hua Zhou; Li-Heng Liu


    A novel integrated design strategy for robust fault diagnosis and fault-tolerant control (FTC) of a class of nonlinear uncertain systems is proposed. The uncertainties considered in this paper are more general than those in other existing works, and faults are described in a new formulation. It is proven that the states of a closed-loop system converge asymptotically to zero even if there are uncertainties and faults in a system. Simulation results on a simple pendulum are presented for illustration.

  4. Probabilistic Fault Diagnosis in Electrical Power Systems (United States)

    National Aeronautics and Space Administration — Electrical power systems play a critical role in spacecraft and aircraft. This paper discusses our development of a diagnostic capability for an electrical power...

  5. Design and implementation of an expert system for remote fault diagnosis in ship lift

    Institute of Scientific and Technical Information of China (English)


    In this paper an expert system for remote fault diagnosis in the ship lift was developed by analysis of the fault tree and combination with VPN. The fault tree was constructed based on the operation condition of the ship lift. The diagnosis model was constructed by hierarchical classification of the fault tree structure, and the inference mechanism was given. Logical structure of the fault diagnosis in the ship lift was proposed. The implementation of the expert system for remote fault diagnosis in the ship...

  6. Fault Risk Assessment of Underwater Vehicle Steering System Based on Virtual Prototyping and Monte Carlo Simulation

    Directory of Open Access Journals (Sweden)

    He Deyu


    Full Text Available Assessing the risks of steering system faults in underwater vehicles is a human-machine-environment (HME systematic safety field that studies faults in the steering system itself, the driver’s human reliability (HR and various environmental conditions. This paper proposed a fault risk assessment method for an underwater vehicle steering system based on virtual prototyping and Monte Carlo simulation. A virtual steering system prototype was established and validated to rectify a lack of historic fault data. Fault injection and simulation were conducted to acquire fault simulation data. A Monte Carlo simulation was adopted that integrated randomness due to the human operator and environment. Randomness and uncertainty of the human, machine and environment were integrated in the method to obtain a probabilistic risk indicator. To verify the proposed method, a case of stuck rudder fault (SRF risk assessment was studied. This method may provide a novel solution for fault risk assessment of a vehicle or other general HME system.

  7. SIFT - Design and analysis of a fault-tolerant computer for aircraft control. [Software Implemented Fault Tolerant systems (United States)

    Wensley, J. H.; Lamport, L.; Goldberg, J.; Green, M. W.; Levitt, K. N.; Melliar-Smith, P. M.; Shostak, R. E.; Weinstock, C. B.


    SIFT (Software Implemented Fault Tolerance) is an ultrareliable computer for critical aircraft control applications that achieves fault tolerance by the replication of tasks among processing units. The main processing units are off-the-shelf minicomputers, with standard microcomputers serving as the interface to the I/O system. Fault isolation is achieved by using a specially designed redundant bus system to interconnect the processing units. Error detection and analysis and system reconfiguration are performed by software. Iterative tasks are redundantly executed, and the results of each iteration are voted upon before being used. Thus, any single failure in a processing unit or bus can be tolerated with triplication of tasks, and subsequent failures can be tolerated after reconfiguration. Independent execution by separate processors means that the processors need only be loosely synchronized, and a novel fault-tolerant synchronization method is described.

  8. Proposed hybrid superconducting fault current limiter for distribution systems

    Energy Technology Data Exchange (ETDEWEB)

    Elmitwally, A. [Elect. Eng. Dept., Mansoura University, Mansoura 35516 (Egypt)


    In this paper, a new hybrid fault current limiter is proposed for primary distribution systems. It incorporates a high temperature superconducting element in parallel with other two branches. The first is an inductive impedance to share the fault current with. The second branch is a gate-turn-off thyristor switch controlled to work in either of two modes. For the main mode, it controls the temperature of the superconducting element and protect it against damaging excessive heating. Instead, it keeps the device applicable without that superconducting element in the auxiliary operation mode. The design, control and operation of the device is addressed. Its performance in 11 kV distribution systems with DG is investigated. The factors affecting the device behavior for different scenarios are explored. (author)

  9. Design of a Fault Detection and Isolation System for Intelligent Vehicle Navigation System

    Directory of Open Access Journals (Sweden)

    Wei Huang


    Full Text Available This paper deals with the design of a fault detection and isolation (FDI system for an intelligent vehicle, a vehicle equipped with advanced driver assistance system (ADAS. The ADASs are outfitted with sensors for acquiring various information about the vehicle and its surroundings. Since these sensors are sensitive to faults, an efficient FDI system should be developed. The designed FDI system is comprised of three parts: a detection part, a decision part, and a fault management part. The detection part applies a generalized observer scheme (GOS. In the GOS, there is bank of extended Kalman filters (EKFs, each excited by all except one sensor measurement. The residual generated from the measurement update of each EKF is therefore sensitive to all sensor faults but one. This way, the fault sensitivity pattern of the residual makes it possible to detect a fault and locate the faulty sensor. The designed FDI system has been implemented and tested off-line with actual experiment data. Good results have been obtained with diagnosing individual sensor faults and outputting fault-free vehicle states.

  10. Industrial Cost-Benefit Assessment for Fault-tolerant Control Systems

    DEFF Research Database (Denmark)

    Thybo, C.; Blanke, M.


    Economic aspects are decisive for industrial acceptance of research concepts including the promising ideas in fault tolerant control. Fault tolerance is the ability of a system to detect, isolate and accommodate a fault, such that simple faults in a sub-system do not develop into failures...... at a system level. In a design phase for an industrial system, possibilities span from fail safe design where any single point failure is accommodated by hardware, over fault-tolerant design where selected faults are handled without extra hardware, to fault-ignorant design where no extra precaution is taken....... The objective of this paper is to help, in the early product development state, to find the economical most suitable scheme. A salient result is that with increased customer awareness of total cost of ownership, new products can benefit significantly from applying fault tolerant control principles....

  11. Robust observer-based fault estimation and accommodation of discrete-time piecewise linear systems

    DEFF Research Database (Denmark)

    Tabatabaeipour, Mojtaba; Bak, Thomas


    In this paper a new integrated observer-based fault estimation and accommodation strategy for discrete-time piecewise linear (PWL) systems subject to actuator faults is proposed. A robust estimator is designed to simultaneously estimate the state of the system and the actuator fault. Then, the es...

  12. Modeling and Measurement Constraints in Fault Diagnostics for HVAC Systems

    Energy Technology Data Exchange (ETDEWEB)

    Najafi, Massieh; Auslander, David M.; Bartlett, Peter L.; Haves, Philip; Sohn, Michael D.


    Many studies have shown that energy savings of five to fifteen percent are achievable in commercial buildings by detecting and correcting building faults, and optimizing building control systems. However, in spite of good progress in developing tools for determining HVAC diagnostics, methods to detect faults in HVAC systems are still generally undeveloped. Most approaches use numerical filtering or parameter estimation methods to compare data from energy meters and building sensors to predictions from mathematical or statistical models. They are effective when models are relatively accurate and data contain few errors. In this paper, we address the case where models are imperfect and data are variable, uncertain, and can contain error. We apply a Bayesian updating approach that is systematic in managing and accounting for most forms of model and data errors. The proposed method uses both knowledge of first principle modeling and empirical results to analyze the system performance within the boundaries defined by practical constraints. We demonstrate the approach by detecting faults in commercial building air handling units. We find that the limitations that exist in air handling unit diagnostics due to practical constraints can generally be effectively addressed through the proposed approach.

  13. Design of Fault Diagnosis Observer for HAGC System on Strip Rolling Mill

    Institute of Scientific and Technical Information of China (English)

    DONG Min; LIU Cai


    By building mathematical model for HAGC (hydraulic automation gauge control) system of strip rolling mill, treating faults as unknown inputs induced by model uncertainty, and analyzing fault direction, an unknown input fault diagnosis observer group was designed. Fault detection and isolation were realized through making observer residuals robust to specific faults but sensitive to other faults. Sufficient existence conditions and design of the observers were given in detail. Diagnosis observer parameters for servo valve, cylinder, roller and body rolling mill were obtained respectively. The effectiveness of this diagnosis method was proved by actual data simulations.

  14. Research on the Algorithm of Avionic Device Fault Diagnosis Based on Fuzzy Expert System

    Institute of Scientific and Technical Information of China (English)


    Based on the fuzzy expert system fault diagnosis theory, the knowledge base architecture and inference engine algorithm are put forward for avionic device fault diagnosis. The knowledge base is constructed by fault query network, of which the basic element is the test-diagnosis fault unit. Every underlying fault cause's membership degree is calculated using fuzzy product inference algorithm, and the fault answer best selection algorithm is developed, to which the deep knowledge is applied. Using some examples,the proposed algorithm is analyzed for its capability of synthesis diagnosis and its improvement compared to greater membership degree first principle.

  15. Iterative learning based fault diagnosis for discrete linear uncer tain systems

    Institute of Scientific and Technical Information of China (English)

    Wei Cao; Ming Sun


    In order to detect and estimate faults in discrete lin-ear time-varying uncertain systems, the discrete iterative learning strategy is applied in fault diagnosis, and a novel fault detection and estimation algorithm is proposed. And the threshold limited tech-nology is adopted in the proposed algorithm. Within the chosen optimal time region, residual signals are used in the proposed algo-rithm to correct the introduced virtual faults with iterative learning rules, making the virtual faults close to these occurred in practical systems. And the same method is repeated in the rest optimal time regions, thereby reaching the aim of fault diagnosis. The proposed algorithm not only completes fault detection and estimation for dis-crete linear time-varying uncertain systems, but also improves the reliability of fault detection and decreases the false alarm rate. The final simulation results verify the validity of the proposed algorithm.

  16. Reliable H∞ control of discrete-time systems against random intermittent faults (United States)

    Tao, Yuan; Shen, Dong; Fang, Mengqi; Wang, Youqing


    A passive fault-tolerant control strategy is proposed for systems subject to a novel kind of intermittent fault, which is described by a Bernoulli distributed random variable. Three cases of fault location are considered, namely, sensor fault, actuator fault, and both sensor and actuator faults. The dynamic feedback controllers are designed not only to stabilise the fault-free system, but also to guarantee an acceptable performance of the faulty system. The robust H∞ performance index is used to evaluate the effectiveness of the proposed control scheme. In terms of linear matrix inequality, the sufficient conditions of the existence of controllers are given. An illustrative example indicates the effectiveness of the proposed fault-tolerant control method.

  17. Sensor and Actuator Fault-Hiding Reconfigurable Control Design for a Four-Tank System Benchmark

    DEFF Research Database (Denmark)

    Hameed, Ibrahim; El-Madbouly, Esam I; Abdo, Mohamed I


    Fault detection and compensation plays a key role to fulfill high demands for performance and security in today's technological systems. In this paper, a fault-hiding (i.e., tolerant) control scheme that detects and compensates for actuator and sensor faults in a four-tank system benchmark...... Invariant (LTI) system where virtual sensors and virtual actuators are used to correct faulty performance through the use of a pre-fault performance. Simulation results showed that the developed approach can handle different types of faults and able to completely and instantly recover the original system...

  18. Delineation of fault systems on Langeland, Denmark based on AEM data and boreholes

    DEFF Research Database (Denmark)

    Andersen, Theis Raaschou; Westergaard, Joakim Hollenbo; Pytlich, Anders


    and geoelectrical surveys. The data serve as basis for constructing 3D hydrogeological and groundwater models from which site-specific protection zones are establish. At present time dense geophysical mapping covers approximately 45 % of Denmark. Based on a dense Airborne ElectroMagnetic (AEM) survey in combination...... modelling, Fault systems....... with boreholes, three fault systems in the northern part of the island of Langeland, Denmark are mapped. Two of the fault systems were unknown prior to the mapping campaign. The two unknown fault systems are interpreted as a normal fault and graben structures, respectively. The presence of the hanging-wall block...

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

    Betka, Paul; Klepeis, Keith; Mosher, Sharon


    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.

  20. Fault Isolation for Nonlinear Systems Using Flexible Support Vector Regression

    Directory of Open Access Journals (Sweden)

    Yufang Liu


    Full Text Available While support vector regression is widely used as both a function approximating tool and a residual generator for nonlinear system fault isolation, a drawback for this method is the freedom in selecting model parameters. Moreover, for samples with discordant distributing complexities, the selection of reasonable parameters is even impossible. To alleviate this problem we introduce the method of flexible support vector regression (F-SVR, which is especially suited for modelling complicated sample distributions, as it is free from parameters selection. Reasonable parameters for F-SVR are automatically generated given a sample distribution. Lastly, we apply this method in the analysis of the fault isolation of high frequency power supplies, where satisfactory results have been obtained.

  1. Fuzzy Timing Petri Net for Fault Diagnosis in Power System

    Directory of Open Access Journals (Sweden)

    Alireza Tavakholi Ghainani


    Full Text Available A model-based system for fault diagnosis in power system is presented in this paper. It is based on fuzzy timing Petri net (FTPN. The ordinary Petri net (PN tool is used to model the protective components, relays, and circuit breakers. In addition, fuzzy timing is associated with places (token/transition to handle the uncertain information of relays and circuits breakers. The received delay time information of relays and breakers is mapped to fuzzy timestamps, π(τ, as initial marking of the backward FTPN. The diagnosis process starts by marking the backward sub-FTPNs. The final marking is found by going through the firing sequence, σ, of each sub-FTPN and updating fuzzy timestamp in each state of σ. The final marking indicates the estimated fault section. This information is then in turn used in forward FTPN to evaluate the fault hypothesis. The FTPN will increase the speed of the inference engine because of the ability of Petri net to describe parallel processing, and the use of time-tag data will cause the inference procedure to be more accurate.

  2. Crystalline Bedrock Geology, Faulting, and Crustal Architecture in the Larse Region of the Transverse Ranges, Southern California (United States)

    Powell, R. E.


    Spanning the Transverse Ranges (TR) between the northern Los Angeles Basin and the western Mojave Desert (MD), the LARSE lines transect several distinct crystalline blocks: western Transverse Ranges (WTR), San Gabriel Mts-Soledad Basin (SGM), Sierra Pelona (SP), and Liebre Mtn. Juxtaposition of disparate blocks evolved during late Cenozoic (Cz) plate-margin reorganization of early Miocene and older paleogeologic and paleotectonic patterns. Crystalline basement rocks, ranging in age from Proterozoic to mid-Cz, constrain tectonic and near-surface crustal evolution of the region in various ways: (1) by their spatial distribution, (2) by basement-derived clast-types in Cz deposits, and (3) by the age and distribution of weathered zones developed on exhumed basement. Reassembly of paleogeologic patterns in the crystalline terrane of S California provides measurements of overall displacement on strike-slip faults of the San Andreas system. In the LARSE region, right-lateral displacements are demonstrable for the San Gabriel fault (SGF) in the SGM (22-23 km), the Vasquez Creek fault (5-15 km), and the SGF NW of the SGM (42-43 km). Displacement on the San Andreas fault NW of the TR (295 km) is partitioned onto the San Andreas-San Francisquito-Fenner-Clemens Well fault (100 km) and the SGF in the TR, and the post-5 Ma San Andreas fault in and south of the TR (ranging from 160 km along the MD-TR segment to 180 km along the Salton Trough segment). Left-lateral displacement has been demonstrated for the Santa Monica-Raymond fault (11-15 km), the Santa Ynez fault (0 km at its E end to as much as 37 km), and the Garlock fault (48-64 km along its central reach and perhaps as little as 12 km along its western reach). The Vasquez Creek and Santa Monica-Raymond faults are conjugate. Pre-Late Miocene extensional deformation is associated with exhumation of the Pelona Schist in SP and the Chocolate Mts and with ENE-trending left-separation faults in SGM. Reverse displacements are

  3. PV Systems Reliability Final Technical Report: Ground Fault Detection

    Energy Technology Data Exchange (ETDEWEB)

    Lavrova, Olga [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Flicker, Jack David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Johnson, Jay [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)


    We have examined ground faults in PhotoVoltaic (PV) arrays and the efficacy of fuse, current detection (RCD), current sense monitoring/relays (CSM), isolation/insulation (Riso) monitoring, and Ground Fault Detection and Isolation (GFID) using simulations based on a Simulation Program with Integrated Circuit Emphasis SPICE ground fault circuit model, experimental ground faults installed on real arrays, and theoretical equations.

  4. Fault Hydrogeology Characterization for a Civil Infrastructure Project (United States)

    Sholley, M. G.; Waterman, M. K.; Attanayake, P. M.


    Planning for the construction of an 18-ft diameter water conveyance tunnel in Southern California was made additionally complex due to the tunnel alignment crossing the San Andreas Fault and a tunnel portal within an area of elevated groundwater temperatures associated with branches/splays of the Arrowhead Spring fault system. This abstract describes the investigation techniques used to characterize the hydrogeology associated with these faults and the conceptual models developed to assist with hazard mitigation during construction. From an early phase of the project it was recognized that tunneling through the San Andreas Fault posed the risk of increased groundwater inflows and therefore potentially hazardous construction conditions. Characterization of the fault focused on estimating those parameters critical to the groundwater regime. In addition to geologic mapping, several boreholes were drilled and the cores logged to determine rock mass characteristics. Prior to installing monitoring wells in these boreholes, in-situ testing to determine hydraulic conductivity was conducted with a double packer system. Analysis of the packer test results demonstrated that factors found to have significant correspondence to hydraulic conductivity were depth of test and proximity to faults. The combination of rock mass characterization, hydraulic conductivity distribution, and water levels were then used to estimate groundwater inflows to the tunnel. The inflow estimates were developed to provide a measure for determining the need to prevent and control the inflows and in identifying likely delays in construction progress. Two semi-empirical methods were used to evaluate the probable magnitude of tunnel inflow. This combination of field techniques and analyses led to a preliminary understanding of the hydrogeological characteristics of the San Andreas Fault and the potential interaction between tunnel construction and the groundwater resource. A detailed understanding of the

  5. Fault Diagnosis Approach of Local Ventilation System in Coal Mines Based on Multidisciplinary Technology

    Institute of Scientific and Technical Information of China (English)

    GONG Xiao-yan; XUE He; TAO Xin-li; HU Ning


    In order to reduce the probability of fault occurrence of local ventilation system in coal mine and prevent gas from exceeding the standard limit, an approach incorporating the reliability analysis, rough set theory, genetic algorithm (GA), and intelligent decision support system (IDSS) was used to establish and develop a fault diagnosis system of local ventilation in coal mine. Fault tree model was established and its reliability analysis was performed. The algorithms and software of key fault symptom and fault diagnosis rule acquiring were also analyzed and developed. Finally, a prototype system was developed and demonstrated by a mine instance. The research results indicate that the proposed approach in this paper can accurately and quickly find the fault reason in a local ventilation system of coal mines and can reduce difficulty of the fault diagnosis of the local ventilation system, which is significant to decrease gas exploding accidents in coal mines.

  6. Field Guide for Testing Existing Photovoltaic Systems for Ground Faults and Installing Equipment to Mitigate Fire Hazards

    Energy Technology Data Exchange (ETDEWEB)

    Brooks, William [Brooks Engineering, Vacaville, CA (United States); Basso, Thomas [National Renewable Energy Lab. (NREL), Golden, CO (United States); Coddington, Michael [National Renewable Energy Lab. (NREL), Golden, CO (United States)


    Ground faults and arc faults are the two most common reasons for fires in photovoltaic (PV) arrays and methods exist that can mitigate the hazards. This report provides field procedures for testing PV arrays for ground faults, and for implementing high resolution ground fault and arc fault detectors in existing and new PV system designs.

  7. Offset of latest pleistocene shoreface reveals slip rate on the Hosgri strike-slip fault, offshore central California (United States)

    Johnson, Samuel Y.; Hartwell, Stephen R.; Dartnell, Peter


    The Hosgri fault is the southern part of the regional Hosgri–San Gregorio dextral strike‐slip fault system, which extends primarily in the offshore for about 400 km in central California. Between Morro Bay and San Simeon, high‐resolution multibeam bathymetry reveals that the eastern strand of the Hosgri fault is crossed by an ∼265  m wide slope interpreted as the shoreface of a latest Pleistocene sand spit. This sand spit crossed an embayment and connected a western fault‐bounded bedrock peninsula and an eastern bedrock highland, a paleogeography resembling modern coastal geomorphology along the San Andreas fault. Detailed analysis of the relict shoreface with slope profiles and slope maps indicates a lateral slip rate of 2.6±0.9  mm/yr, considered a minimum rate for the Hosgri given the presence of an active western strand. This slip rate indicates that the Hosgri system takes up the largest share of the strike‐slip fault budget and is the most active strike‐slip fault west of the San Andreas fault in central California. This result further demonstrates the value and potential of high‐resolution bathymetry in characterization of active offshore faults.

  8. Application of three fault growth criteria to the Puente Hills thrust system, Los Angeles, California, USA (United States)

    Olson, Erik L.; Cooke, Michele L.


    Three-dimensional mechanical models are used to evaluate the performance of different fault growth criteria in predicting successive growth of three échelon thrust faults similar to the segments of the Puente Hills thrust system of the Los Angeles basin, California. Four sequential Boundary Element Method models explore the growth of successive échelon faults within the system by simulating snapshots of deformation at different stages of development. These models use three criteria, (1) energy release rate, (2) strain energy density, and (3) Navier-Coulomb stress, to characterize the lateral growth of the fault system. We simulate the growth of an échelon thrust fault system to evaluate the suitability of each of these criteria for assessing fault growth. Each of these three factors predicts a portion of the incipient fault geometry (i.e. location or orientation); however, each provides different information. In each model, energy release rate along the westernmost (leading) tip of the Puente Hills thrust drops with growth of the next neighboring fault; this result supports the overall lateral development of successive échelon segments. Within each model, regions of high strain energy density and Navier-Coulomb stress envelope at least a portion of the next fault to develop, although the strain energy density has stronger correlation than Navier-Coulomb stress to the location of incipient faulting. In each model, one of the two predicted planes of maximum Navier-Coulomb stress ahead of the leading fault tip matches the strike but not the dip of the incipient fault plane recreating part of the fault orientation. The incipient fault dip is best predicted by the orientation of the strain energy density envelopes around the leading fault tip. Furthermore, the energy release rate and pattern of strain energy density can be used to characterize potential soft linkage (overlap) or hard linkage (connection) of échelon faults within the system.

  9. On-Line Broken-Bar Fault Diagnosis System of Induction Motor

    Institute of Scientific and Technical Information of China (English)

    ZHANG Rong; WANG Xiuhe


    Induction motor faults including mechanical and electrical faults are reviewed. The fault diagnosis methods are summarized. To analyze the influence of stator current, torque, speed and rotor current on faulted bars, a time-stepping transient finite element (FE) model of induction motor with bars faulted is created in this paper. With wavelet package analysis method and FFT method, the simulation result of finite element is analyzed. Based on the simulation analysis, the on-line fault diagnosis system of induction motor with bars faulted is developed. With the speed of broken bars motor changed from 1 478 r/min to 1 445 r/min, the FFT power spectra and the wavelet package decoupling factors are given. The comparison result shows that the on-line diagnosis system can detect broken-bar fault efficiently.

  10. Offset of Latest Pleistocene Shoreface Reveals Slip Rate on the Hosgri Strike-Slip Fault, Offshore Central California (United States)

    Johnson, S. Y.; Hartwell, S. R.; Dartnell, P.


    The Hosgri fault is the southern part of the regional Hosgri-San Gregorio dextral strike-slip fault system, which extends primarily in the offshore region for about 400 km in central California. Between Morro Bay and San Simeon, high-resolution multibeam bathymetry reveals that the eastern strand of the Hosgri fault is crossed by a ~265-m-wide slope interpreted as the shoreface of a relict sand spit that formed during a period of relatively slower sea-level rise (Younger Dryas stadial) in the latest Pleistocene. This sand spit crossed an embayment and connected a western fault-bounded bedrock peninsula and an eastern bedrock highland, a paleogeography similar to modern geomorphology along coastal segments of the San Andreas fault. Detailed analysis of the relict shoreface with slope profiles and slope maps indicates a lateral slip rate of 2.6 ± 0.9 mm/yr. Because the Hosgri fault locally includes an active western strand, and regionally converges with several other faults, this slip rate should be considered a minimum for the Hosgri fault in central California and should not be applied for the entire Hosgri-San Gregorio fault system. This slip rate indicates that the Hosgri system takes up the largest share of the strike-slip fault budget and is the most active strike-slip fault west of the San Andreas fault in central California. This result further demonstrates the value and potential of high-resolution bathymetry in earthquake-hazard characterization of active offshore faults.

  11. Wavelet Based Fault Detection, Classification in Transmission System with TCSC Controllers

    Directory of Open Access Journals (Sweden)



    Full Text Available This paper presents simulation results of the application of distance relays for the protection of transmission systems employing flexible alternating current transmission controllers such as Thyristor Controlled Series Capacitor (TCSC. The complete digital simulation of TCSC within a transmission system is performed in the MATLAB/Simulink environment using the Power System Block set (PSB. This paper presents an efficient method based on wavelet transforms both fault detection and classification which is almost independent of fault impedance, fault location and fault inception angle of transmission line fault currents with FACTS controllers.

  12. Towards fault-tolerant decision support systems for ship operator guidance

    DEFF Research Database (Denmark)

    Nielsen, Ulrik Dam; Lajic, Zoran; Jensen, Jørgen Juncher


    Fault detection and isolation are very important elements in the design of fault-tolerant decision support systems for ship operator guidance. This study outlines remedies that can be applied for fault diagnosis, when the ship responses are assumed to be linear in the wave excitation. A novel...

  13. Method for detecting an open-switch fault in a grid-connected NPC inverter system

    DEFF Research Database (Denmark)

    Choi, Ui-Min; Jeong, Hae-Gwang; Lee, Kyo-Beum;


    This paper proposes a fault-detection method for an open-switch fault in the switches of grid-connected neutral-point-clamped inverter systems. The proposed method can not only detect the fault condition but also identify the location of the faulty switch. In the proposed method, which is designed...

  14. Observer-based Fault Detection and Isolation for Nonlinear Systems

    DEFF Research Database (Denmark)

    Lootsma, T.F.

    . Then the geometric approach is applied to a nonlinear ship propulsion system benchmark. The calculations and application results are presented in detail to give an illustrative example. The obtained subsystems are considered for the design of nonlinear observers in order to obtain FDI. Additionally, an adaptive...... for the observers designed for the ship propulsion system. Furthermore, it stresses the importance of the time-variant character of the linearization along a trajectory. It leads to a different stability analysis than for linearization at one operation point. Finally, the preliminary concept of (actuator) fault...

  15. Automated Fault Diagnostics, Prognostics, and Recovery in Spacecraft Power Systems Project (United States)

    National Aeronautics and Space Administration — Fault detection and isolation (FDI) in spacecraft's electrical power system (EPS) has always received special attention. However, the power systems health management...

  16. Modeling the Fault Tolerant Capability of a Flight Control System: An Exercise in SCR Specification (United States)

    Alexander, Chris; Cortellessa, Vittorio; DelGobbo, Diego; Mili, Ali; Napolitano, Marcello


    In life-critical and mission-critical applications, it is important to make provisions for a wide range of contingencies, by providing means for fault tolerance. In this paper, we discuss the specification of a flight control system that is fault tolerant with respect to sensor faults. Redundancy is provided by analytical relations that hold between sensor readings; depending on the conditions, this redundancy can be used to detect, identify and accommodate sensor faults.

  17. Slip distribution, strain accumulation and aseismic slip on the Chaman Fault system (United States)

    Amelug, F.


    The Chaman fault system is a transcurrent fault system developed due to the oblique convergence of the India and Eurasia plates in the western boundary of the India plate. To evaluate the contemporary rates of strain accumulation along and across the Chaman Fault system, we use 2003-2011 Envisat SAR imagery and InSAR time-series methods to obtain a ground velocity field in radar line-of-sight (LOS) direction. We correct the InSAR data for different sources of systematic biases including the phase unwrapping errors, local oscillator drift, topographic residuals and stratified tropospheric delay and evaluate the uncertainty due to the residual delay using time-series of MODIS observations of precipitable water vapor. The InSAR velocity field and modeling demonstrates the distribution of deformation across the Chaman fault system. In the central Chaman fault system, the InSAR velocity shows clear strain localization on the Chaman and Ghazaband faults and modeling suggests a total slip rate of ~24 mm/yr distributed on the two faults with rates of 8 and 16 mm/yr, respectively corresponding to the 80% of the total ~3 cm/yr plate motion between India and Eurasia at these latitudes and consistent with the kinematic models which have predicted a slip rate of ~17-24 mm/yr for the Chaman Fault. In the northern Chaman fault system (north of 30.5N), ~6 mm/yr of the relative plate motion is accommodated across Chaman fault. North of 30.5 N where the topographic expression of the Ghazaband fault vanishes, its slip does not transfer to the Chaman fault but rather distributes among different faults in the Kirthar range and Sulaiman lobe. Observed surface creep on the southern Chaman fault between Nushki and north of City of Chaman, indicates that the fault is partially locked, consistent with the recorded MBalochistan and the populated areas such as the city of Quetta.

  18. ISHM-oriented adaptive fault diagnostics for avionics based on a distributed intelligent agent system (United States)

    Xu, Jiuping; Zhong, Zhengqiang; Xu, Lei


    In this paper, an integrated system health management-oriented adaptive fault diagnostics and model for avionics is proposed. With avionics becoming increasingly complicated, precise and comprehensive avionics fault diagnostics has become an extremely complicated task. For the proposed fault diagnostic system, specific approaches, such as the artificial immune system, the intelligent agents system and the Dempster-Shafer evidence theory, are used to conduct deep fault avionics diagnostics. Through this proposed fault diagnostic system, efficient and accurate diagnostics can be achieved. A numerical example is conducted to apply the proposed hybrid diagnostics to a set of radar transmitters on an avionics system and to illustrate that the proposed system and model have the ability to achieve efficient and accurate fault diagnostics. By analyzing the diagnostic system's feasibility and pragmatics, the advantages of this system are demonstrated.

  19. Fault Self-Diagnosis for Modular Robotic Systems Using M-Lattice Modules

    Directory of Open Access Journals (Sweden)

    Enguang Guan


    Full Text Available In the domain of modular robotic systems, self-configuration, self-diagnosis and self-repair are known to be highly challenging tasks. This paper presents a novel fault self-diagnosis strategy which consists of two parts: fault detection and fault message transmission. In fault detection, a bionic synchronization ‘healthy heartbeat’ method is used to guarantee the high efficiency of the exogenous detection strategy. For fault message transmission, the Dijkstra method is modified to be capable of guiding the passage of fault messages along the optimal path. In a modular robotic system, fault message transmission depends mainly on local communications between adjacent modules, so there is no need for global broadcast information. Computational simulations of one system form, M-Lattice, have demonstrated the practical effectiveness of the proposed strategy. The strategy should be applicable in modular robotic systems in general.

  20. Fault Estimation

    DEFF Research Database (Denmark)

    Stoustrup, Jakob; Niemann, H.


    This paper presents a range of optimization based approaches to fault diagnosis. A variety of fault diagnosis prob-lems are reformulated in the so-called standard problem setup introduced in the literature on robust control. Once the standard problem formulations are given, the fault diagnosis pr...... problems can be solved by standard optimization tech-niques. The proposed methods include: (1) fault diagnosis (fault estimation, (FE)) for systems with model uncertainties; (2) FE for systems with parametric faults, and (3) FE for a class of nonlinear systems.......This paper presents a range of optimization based approaches to fault diagnosis. A variety of fault diagnosis prob-lems are reformulated in the so-called standard problem setup introduced in the literature on robust control. Once the standard problem formulations are given, the fault diagnosis...

  1. Broadband Ground Motion Simulations for the Puente Hills Fault System (United States)

    Graves, R. W.


    Recent geologic studies have identified the seismic potential of the Puente Hills fault system. This system is comprised of multiple blind thrust segments, a portion of which ruptured in the Mw 5.9 Whittier-Narrows earthquake. Rupture of the entire system could generate a Mw 7.2 (or larger) earthquake. To assess the potential hazard posed by the fault system, we have simulated the response for several earthquake scenarios. These simulations are unprecedented in scope and scale. Broadband (0-10 Hz) ground motions are computed at 66,000 sites, covering most of the LA metropolitan region. Low frequency (f 1 Hz) motions are calculated using a stochastic approach. We consider scenarios ranging from Mw 6.7 to Mw 7.2, including both high and low stress drop events. Finite-fault rupture models for these scenarios are generated following a wavenumber filtering technique (K-2 model) that has been calibrated against recent earthquakes. In all scenarios, strong rupture directivity channels large amplitude pulses of motion directly into the Los Angeles basin, which then propagate southward as basin surface waves. Typically, the waveforms near downtown Los Angeles are dominated by a strong, concentrated pulse of motion. At Long Beach (across the LA basin from the rupture) the waveforms are dominated by late arriving longer period surface waves. The great density of sites used in the calculation allows the construction of detailed maps of various ground motion parameters (PGA, PGV, SA), as well as full animations of the propagating broadband wave field. Additionally, the broadband time histories are available for use in non-linear response analyses of built structures.

  2. Characteristics of earth faults in power systems with a compensated or an unearthed neutral

    Energy Technology Data Exchange (ETDEWEB)

    Haenninen, S.; Lehtonen, M. [VTT Energy, Espoo (Finland); Antila, E. [ABB Transmit Oy (Finland); Stroem, J. [Espoo Electricity Co (Finland); Ingman, S. [Vaasa Electricity Co (Finland)


    The most common fault type in the electrical distribution networks is the single phase to earth fault. For instance in the Nordic countries, about 80 % of all faults are of this type. To develop the protection and fault location systems, it is important to obtain real case data of disturbances and faults which occurred in the networks. Therefore, data of fault occurrences have been recorded and analyzed in the medium voltage distribution networks (20 kV) at two substations, of which one has an isolated and the other a compensated neutral. In the occurring disturbances, the traces of phase currents and neutral currents in the beginning of two feeder and the traces of phase voltages and neutral voltage from the voltage measuring bay were recorded. In addition to the measured data, other information of the fault occurrences was also collected (data of the line, cause and location of permanent faults and so on)

  3. Measurement and analysis of workload effects on fault latency in real-time systems (United States)

    Woodbury, Michael H.; Shin, Kang G.


    The authors demonstrate the need to address fault latency in highly reliable real-time control computer systems. It is noted that the effectiveness of all known recovery mechanisms is greatly reduced in the presence of multiple latent faults. The presence of multiple latent faults increases the possibility of multiple errors, which could result in coverage failure. The authors present experimental evidence indicating that the duration of fault latency is dependent on workload. A synthetic workload generator is used to vary the workload, and a hardware fault injector is applied to inject transient faults of varying durations. This method makes it possible to derive the distribution of fault latency duration. Experimental results obtained from the fault-tolerant multiprocessor at the NASA Airlab are presented and discussed.

  4. Active fault segments as potential earthquake sources: Inferences from integrated geophysical mapping of the Magadi fault system, southern Kenya Rift (United States)

    Kuria, Z. N.; Woldai, T.; van der Meer, F. D.; Barongo, J. O.


    uplifted, heavily fractured and deformed basin to the north (highly disturbed magnetic signatures) characteristic of on going active rifting; and a refined architecture of the asymmetry graben to the south with an intrarift horst, whose western graben is 4 km deep and eastern graben is much deeper (9 km), with a zone of significant break in magnetic signatures at that depth, interpreted as source of the hot springs south of Lake Magadi (a location confirmed near surface by ground magnetic and resistivity data sets). The magnetic sources to the north are shallow at 15 km depth compared to 22 km to the south. The loss of magnetism to the north is probably due to increased heat as a result of magmatic intrusion supporting active rifting model. Conclusively, the integrated approach employed in this research confirms that fault system delineated to the north is actively deforming under E-W normal extension and is a potential earthquake source probably related to magmatic intrusion, while the presence of fluids within the south fault zone reduce intensity of faulting activity and explains lack of earthquakes in a continental rift setting.

  5. A Fuzzy Mathematics Based Fault Auto-diagnosis System for Vacuum Resin Shot Dosing Equipment

    Institute of Scientific and Technical Information of China (English)


    On the basis of the analysis of faults and their causes of vacuum resin shot dosing equipment, the fuzzy model of fault diagnosis for the equipment is constructed, and the fuzzy relationship matrix, the symptom fuzzy vector, the fuzzy compound arithmetic operator, and the diagnosis principle of the model are determined. Then the fault auto-diagnosis system for the equipment is designed, and the functions for real-time monitoring its operation condition and for fault auto-diagnosis are realized. Finally, the experiments of fault auto-diagnosis are conducted in practical production and the veracity of the system is verified.

  6. Slip rate variability over the Holocene period in the middle Aterno fault system (Italy), retrieved from in situ 36Cl cosmogenic nuclide dating of exhumed fault-plane. (United States)

    Tesson, Jim; Benedetti, Lucilla; Pucci, Stefano; Villani, Fabio; Bourles, Didier; Keddadouche, Karim; Aumaitre, Georges


    Numerous numerical modeling studies have described and quantified non-stochastic spatio-temporal variations of earthquake occurrences within fault-networks, such as temporal clustered earthquakes or fault synchronization. However, very few long-enough paleoseismological and geological records are available to test those models against well-constrained dataset and thus account for such variability in the fault behavior. The prerequisites for improving our understanding of fault-rupture processes and thus our capacity to better assess seismic hazard are to acquire paleoseismological records that enable to derive both long-term slip-rate and short-term variability, on a large population of faults and/or within a fault system. These conditions met in Central Apennines, an extensional province where substantial paleoseismological dataset accurately described the Holocene seismic history of a dense network of normal faults. In this study we use 36Cl in situ cosmogenic nuclide to retrieve the seismic history of 3 faults belonging to the Middle Aterno fault system, from north to south: the Bazzano fault, the Roccapreturo fault and the Sulmona fault, a portion of which ruptured during the 2009 L'Aquila earthquake in Italy. We use a new modeling approach to determine the age and slip of past seismic events from the 36Cl concentration profiles. This model is based on an inverse approach and uses an optimization algorithm enabling all the parameter space (number of events, age and slip of events, pre-exposure) to be explored without a priori constraints (see Tesson et al. in session TS4.2/NH4.16/SM3.8). Using this new approach, we precisely determine the slip events occurrences over the Holocene period of those three faults. The results indicate that the three studied faults have ruptured between 4.5 and 5.5 ka, while the southernmost part of the system has also ruptured between at 1.5-3 ka (Sulmona fault and southern segment of Roccapreturo). Those results are in agreement

  7. Sensor Fault and Delay Tolerant Control for Networked Control Systems Subject to External Disturbances. (United States)

    Han, Shi-Yuan; Chen, Yue-Hui; Tang, Gong-You


    In this paper, the problem of sensor fault and delay tolerant control problem for a class of networked control systems under external disturbances is investigated. More precisely, the dynamic characteristics of the external disturbance and sensor fault are described as the output of exogenous systems first. The original sensor fault and delay tolerant control problem is reformulated as an equivalence problem with designed available system output and reformed performance index. The feedforward and feedback sensor fault tolerant controller (FFSFTC) can be obtained by utilizing the solutions of Riccati matrix equation and Stein matrix equation. Based on the designed fault diagnoser, the proposed FFSFTC is further reconstructed to compensate for the sensor fault and delayed measurement effects. Finally, numerical examples are provided to illustrate the effectiveness of our proposed FFSFTC with different cases with various types of sensor faults, measurement delays and external disturbances.

  8. Piecewise Sliding Mode Decoupling Fault Tolerant Control System

    Directory of Open Access Journals (Sweden)

    Rafi Youssef


    Full Text Available Problem statement: Proposed method in the present study could deal with fault tolerant control system by using the so called decentralized control theory with decoupling fashion sliding mode control, dealing with subsystems instead of whole system and to the knowledge of the author there is no known computational algorithm for decentralized case, Approach: In this study we present a decoupling strategy based on the selection of sliding surface, which should be in piecewise sliding surface partition to apply the PwLTool which have as purpose in our case to delimit regions where sliding mode occur, after that as Results: We get a simple linearized model selected in those regions which could depict the complex system, Conclusion: With the 3 water tank level system as example we implement this new design scenario and since we are interested in networked control system we believe that this kind of controller implementation will not be affected by network delays.

  9. Knowledge-based fault diagnosis system for refuse collection vehicle (United States)

    Tan, CheeFai; Juffrizal, K.; Khalil, S. N.; Nidzamuddin, M. Y.


    The refuse collection vehicle is manufactured by local vehicle body manufacturer. Currently; the company supplied six model of the waste compactor truck to the local authority as well as waste management company. The company is facing difficulty to acquire the knowledge from the expert when the expert is absence. To solve the problem, the knowledge from the expert can be stored in the expert system. The expert system is able to provide necessary support to the company when the expert is not available. The implementation of the process and tool is able to be standardize and more accurate. The knowledge that input to the expert system is based on design guidelines and experience from the expert. This project highlighted another application on knowledge-based system (KBS) approached in trouble shooting of the refuse collection vehicle production process. The main aim of the research is to develop a novel expert fault diagnosis system framework for the refuse collection vehicle.

  10. Knowledge-based fault diagnosis system for refuse collection vehicle

    Energy Technology Data Exchange (ETDEWEB)

    Tan, CheeFai; Juffrizal, K.; Khalil, S. N.; Nidzamuddin, M. Y. [Centre of Advanced Research on Energy, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, Durian Tunggal, Melaka (Malaysia)


    The refuse collection vehicle is manufactured by local vehicle body manufacturer. Currently; the company supplied six model of the waste compactor truck to the local authority as well as waste management company. The company is facing difficulty to acquire the knowledge from the expert when the expert is absence. To solve the problem, the knowledge from the expert can be stored in the expert system. The expert system is able to provide necessary support to the company when the expert is not available. The implementation of the process and tool is able to be standardize and more accurate. The knowledge that input to the expert system is based on design guidelines and experience from the expert. This project highlighted another application on knowledge-based system (KBS) approached in trouble shooting of the refuse collection vehicle production process. The main aim of the research is to develop a novel expert fault diagnosis system framework for the refuse collection vehicle.

  11. Fault detection and isolation of sensors in aeration control systems. (United States)

    Carlsson, Bengt; Zambrano, Jesús


    In this paper, we consider the problem of fault detection (FD) and isolation in the aeration system of an activated sludge process. For this study, the dissolved oxygen in each aerated zone is assumed to be controlled automatically. As the basis for an FD method we use the ratio of air flow rates into different zones. The method is evaluated in two scenarios: using the Benchmark Simulation Model no. 1 (BSM1) by Monte Carlo simulations and using data from a wastewater treatment plant. The FD method shows good results for a correct and early FD and isolation.

  12. Map and Data for Quaternary Faults and Fault Systems on the Island of Hawai`i (United States)

    Cannon, Eric C.; Burgmann, Roland; Crone, Anthony J.; Machette, Michael N.; Dart, Richard L.


    Introduction This report and digitally prepared, GIS-based map is one of a series of similar products covering individual states or regions of United States that show the locations, ages, and activity rates of major earthquake-related features such as faults and fault-related folds. It is part of a continuing the effort to compile a comprehensive Quaternary fault and fold map and database for the United States, which is supported by the U.S. Geological Survey's (USGS) Earthquake Hazards Program. Guidelines for the compilation of the Quaternary fault and fold maps for the United States were published by Haller and others (1993) at the onset of this project. This compilation of Quaternary surface faulting and folding in Hawai`i is one of several similar state and regional compilations that were planned for the United States. Reports published to date include West Texas (Collins and others, 1996), New Mexico (Machette and others, 1998), Arizona (Pearthree, 1998), Colorado (Widmann and others, 1998), Montana (Stickney and others, 2000), Idaho (Haller and others, 2005), and Washington (Lidke and others, 2003). Reports for other states such as California and Alaska are still in preparation. The primary intention of this compilation is to aid in seismic-hazard evaluations. The report contains detailed information on the location and style of faulting, the time of most recent movement, and assigns each feature to a slip-rate category (as a proxy for fault activity). It also contains the name and affiliation of the compiler, date of compilation, geographic and other paleoseismologic parameters, as well as an extensive set of references for each feature. The map (plate 1) shows faults, volcanic rift zones, and lineaments that show evidence of Quaternary surface movement related to faulting, including data on the time of most recent movement, sense of movement, slip rate, and continuity of surface expression. This compilation is presented as a digitally prepared map product

  13. Fault Prediction in Object Oriented System Using the Coupling and Cohesion of Classes

    Directory of Open Access Journals (Sweden)

    Mr. Amol S. Dange


    Full Text Available Building efficient systems is one of the main challenges for softwaredevelopers, who have been concerned with dependability-related issues asthey built and deployed. Lots of changes often needs including the nature offaults and failures and the complexity of systems. Sometimes acceptingminor errors always need efforts to eliminate faults that might cause them isin the core of dependability. To this end various fault tolerance mechanismshave been investigated by researchers and used in industry. Unfortunately,more often than not these solutions exclusively focus on the implementation,ignoring other development phases, most importantly the earlier ones. Thiscreates a dangerous gap between the requirement to build dependable (andfault prediction systems and the fact that it is not dealt with until theimplementation step.A current software engineering gives attention towards only normal behaviorwith assumption that all faults can be removed during development. In factevery phase SDLC needs to be focused with phase-specific fault detectionmeans.We mean to conclude that SDLC requires: Integration of fault detection starting from requirement andarchitecture. Making fault detection-related decisions at each phase by explicitmodeling of faults. Developing dedicated tools for fault detection modeling; providingdomain-specific application-level fault prediction mechanisms.Part I: Fault Prediction engineering: from requirements to codePart II: Languages and Tools for engineering fault prediction systems

  14. Single Ended Fault Location Estimation for EHV Transmission Systems

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qing-chao张庆超; LI Hui李晖; D. W. P. Thomas


    A novel numerical algorithm for fault location estimation of single-phase-to-earth fault on EHV transmission lines is presented in this paper. The method is based on one-terminal voltage and current data and is used in a procedure that provides the automatic determination of faulted types and phases, rather than requires engineer to specify them. The loop and nodal equations comparing the faulted phase to non-faulted phases of multi-parallel lines are introduced in the fault location estimation models, in which source impedance of remote end is not involved. Precise algorithms of locating fault are derived. The effect of load flow and fault resistance,on the location accuracy, are effectively eliminated. The algorithms are demonstrated by digital computer simulations.

  15. Strain localisation and population changes during fault system growth within the Inner Moray Firth, Northern North Sea (United States)

    Walsh, J. J.; Childs, C.; Imber, J.; Manzocchi, T.; Watterson, J.; Nell, P. A. R.


    The evolution of fault populations is established for an area within the Late Jurassic Inner Moray Firth sub-basin of the North Sea. Sedimentation rates outstripped fault displacement rates resulting in the blanketing of fault scarps and the preservation of fault displacement histories. Displacement backstripping is used to establish the growth history of the fault system. Fault system evolution is characterised by early generation of the main fault pattern and progressive localisation of strain onto larger faults. This localisation is accompanied by the death of smaller faults and an associated change in the active fault population from power-law to scale-bound. Fault length populations evolve from a power-law frequency distribution containing all faults, to a power-law distribution with a marked non-power-law tail containing the largest faults. This change in population character is synchronous with the development of a fully-connected fault system extending across the mapped area and the accommodation of displacements almost exclusively on the largest faults. Strain localisation onto fewer and better connected faults represents the most efficient means of accommodating fault-related deformation and is considered to be a fundamental characteristic of the spatio-temporal evolution of fault systems. Progressive strain localisation requires complementary changes in the characteristics of associated earthquake populations.

  16. Robust Fault Detection for a Class of Uncertain Nonlinear Systems Based on Multiobjective Optimization

    Directory of Open Access Journals (Sweden)

    Bingyong Yan


    Full Text Available A robust fault detection scheme for a class of nonlinear systems with uncertainty is proposed. The proposed approach utilizes robust control theory and parameter optimization algorithm to design the gain matrix of fault tracking approximator (FTA for fault detection. The gain matrix of FTA is designed to minimize the effects of system uncertainty on residual signals while maximizing the effects of system faults on residual signals. The design of the gain matrix of FTA takes into account the robustness of residual signals to system uncertainty and sensitivity of residual signals to system faults simultaneously, which leads to a multiobjective optimization problem. Then, the detectability of system faults is rigorously analyzed by investigating the threshold of residual signals. Finally, simulation results are provided to show the validity and applicability of the proposed approach.

  17. Sensor fault diagnosis of time-delay systems based on adaptive observer

    Institute of Scientific and Technical Information of China (English)

    YOU Fu-qiang; TIAN Zuo-hua; SHI Song-jiao


    Presents a novel approach for the sensor fault diagnosis of time-delay systems by using an adaptive observer technique. The sensor fault is modeled as an additive perturbation described by a time varying function. Systems without model uncertainty are initially considered, followed by a discussion of a general situation where the system is subjected to either model uncertainty or external disturbance. An adaptive diagnostic algorithm is developed to diagnose the fault, and a modified version is proposed for general system to improve robustness. The stability of fault diagnosis system is proved. Finally, a numerical example is given to illustrate the efficiency of the proposed method.

  18. A New Approach to Fault Diagnosis of Power Systems Using Fuzzy Reasoning Spiking Neural P Systems

    Directory of Open Access Journals (Sweden)

    Guojiang Xiong


    Full Text Available Fault diagnosis of power systems is an important task in power system operation. In this paper, fuzzy reasoning spiking neural P systems (FRSN P systems are implemented for fault diagnosis of power systems for the first time. As a graphical modeling tool, FRSN P systems are able to represent fuzzy knowledge and perform fuzzy reasoning well. When the cause-effect relationship between candidate faulted section and protective devices is represented by the FRSN P systems, the diagnostic conclusion can be drawn by means of a simple parallel matrix based reasoning algorithm. Three different power systems are used to demonstrate the feasibility and effectiveness of the proposed fault diagnosis approach. The simulations show that the developed FRSN P systems based diagnostic model has notable characteristics of easiness in implementation, rapidity in parallel reasoning, and capability in handling uncertainties. In addition, it is independent of the scale of power system and can be used as a reliable tool for fault diagnosis of power systems.

  19. Data-driven design of fault diagnosis systems nonlinear multimode processes

    CERN Document Server

    Haghani Abandan Sari, Adel


    In many industrial applications early detection and diagnosis of abnormal behavior of the plant is of great importance. During the last decades, the complexity of process plants has been drastically increased, which imposes great challenges in development of model-based monitoring approaches and it sometimes becomes unrealistic for modern large-scale processes. The main objective of Adel Haghani Abandan Sari is to study efficient fault diagnosis techniques for complex industrial systems using process historical data and considering the nonlinear behavior of the process. To this end, different methods are presented to solve the fault diagnosis problem based on the overall behavior of the process and its dynamics. Moreover, a novel technique is proposed for fault isolation and determination of the root-cause of the faults in the system, based on the fault impacts on the process measurements. Contents Process monitoring Fault diagnosis and fault-tolerant control Data-driven approaches and decision making Target...

  20. Robust On-Line Fault Diagnosis for Nonlinear Difference-Algebraic Systems Using Least Squares Estimate

    Institute of Scientific and Technical Information of China (English)


    A new robust on-line fault diagnosis method based on least squares estimate for nonlinear difference-algebraic systems (DAS) with uncertainties is proposed. Based on the known nominal model of the DAS, this method firstly constructs an auxiliary system consisting of a difference equation and an algebraic equation, then, based on the relationship between the state deviation and the faults in the difference equation and the relationship between the algebraic variable deviation and the faults in algebraic equation, it identifies the faults on-line through least squares estimate. This method can not only detect, isolate and identify faults for DAS, but also give the upper bound of the error of fault identification. The simulation results indicate that it can give satisfactory diagnostic results for both abrupt and incipient faults.

  1. Dr Andrea Granelli, Vice President, Telecom Italia

    CERN Multimedia

    Patrice Loïez


    Photo 06: Dr Andrea Granelli, Chief Executive Officer, Telecom Italia Lab (second from right) visiting the LHC superconducting magnet test hall with (from left to right) M. Cecchi , F. Gagliardi and G. Cavallari. Photo 15: Dr Andrea Granelli, Chief Executive Officer, Telecom Italia Lab (left) visiting the LHC superconducting magnet test hall with (from left to right) M. Cecchi and G. Cavallari.

  2. Tsunamigenic potential of Mediterranean fault systems and active subduction zones (United States)

    Petricca, Patrizio; Babeyko, Andrey


    Since the North East Atlantic and Mediterranean Tsunami Warning System (NEAMTWS) is under development by the European scientific community, it becomes necessary to define guidelines for the characterization of the numerous parameters must be taken into account in a fair assessment of the risk. Definition of possible tectonic sources and evaluation of their potential is one of the principal issues. In this study we systematically evaluate tsunamigenic potential of up-to-now known real fault systems and active subduction interfaces in the NEAMTWS region. The task is accomplished by means of numerical modeling of tsunami generation and propagation. We have simulated all possible uniform-slip ruptures populating fault and subduction interfaces with magnitudes ranging from 6.5 up to expected Mmax. A total of 15810 individual ruptures were processed. For each rupture, a tsunami propagation scenario was computed in linear shallow-water approximation on 1-arc minute bathymetric grid (Gebco_08) implying normal reflection boundary conditions. Maximum wave heights at coastal positions (totally - 23236 points of interest) were recorded for four hours of simulation and then classified according to currently adopted warning level thresholds. The resulting dataset allowed us to classify the sources in terms of their tsunamigenic potential as well as to estimate their minimum tsunamigenic magnitude. Our analysis shows that almost every source in the Mediterranean Sea is capable to produce local tsunami at the advisory level (i.e., wave height > 20 cm) starting from magnitude values of Mw=6.6. In respect to the watch level (wave height > 50 cm), the picture is less homogeneous: crustal sources in south-west Mediterranean as well as East-Hellenic arc need larger magnitudes (around Mw=7.0) to trigger watch levels even at the nearby coasts. In the context of the regional warning (i.e., source-to-coast distance > 100 km) faults also behave more heterogeneously in respect to the minimum

  3. Actuator Fault Detection for Sampled-Data Systems in H∞ Setting

    Institute of Scientific and Technical Information of China (English)

    YANG Xiao-jun; WENG Zheng-xin; TIAN Zuo-hua


    Actuator fault detection for sampled-data systems was investigated from the viewpoint of jump systems.With the aid of a prior frequency information on fault, such a problem is converted to an augmented H∞ filtering problem. A simple state-space approach is then proposed todeal with sampled-data actuator fault detection problem. Compared with the existed approaches, the proposed approach allows parameters of the sampled-data system being time-varying with consideration of measurement noise.

  4. Faults detection approach using PCA and SOM algorithm in PMSG-WT system

    Directory of Open Access Journals (Sweden)

    Mohamed Lamine FADDA


    Full Text Available In this paper, a new approach for faults detection in observable data system wind turbine - permanent magnet synchronous generator (WT-PMSG, the studying objective, illustrate the combination (SOM-PCA to build Multi-local-PCA models faults detection in system (WT-PMSG, the performance of the method suggested to faults detection in system data, finding good results in simulation experiment.

  5. Fault Rid Through Protection of DFIG Based Wind Generation System

    Directory of Open Access Journals (Sweden)

    S. Sajedi


    Full Text Available This study proposes a fault ride-through strategy for a Doubly Fed Induction Generator (DFIG to enhance network stability during grid disturbances. To enable efficient computation a reduced order DFIG model is developed that restricts the calculation to the fundamental frequency component. However, the model enhancement introduced in the paper allows the consideration of the alternating components of the rotor current as well which is necessary for triggering the crowbar operation. As protection against short circuit transients, the crowbar protection is employed in the simulation. An equivalent model is constructed. Simplifications are made so as to have a system composed of grid, transformer, line and generator represented by elementary circuit elements (R, L, C and voltage sources. Equivalent circuit models are simplified so that the fault models may be used for synchronous machine parameters. It is assumed that the mechanical system cannot respond during the short time of a three phase short circuit. Simulation results in MATLABSimulink software are presented for model verification purposes.

  6. Distributed Evaluation Functions for Fault Tolerant Multi-Rover Systems (United States)

    Agogino, Adrian; Turner, Kagan


    The ability to evolve fault tolerant control strategies for large collections of agents is critical to the successful application of evolutionary strategies to domains where failures are common. Furthermore, while evolutionary algorithms have been highly successful in discovering single-agent control strategies, extending such algorithms to multiagent domains has proven to be difficult. In this paper we present a method for shaping evaluation functions for agents that provide control strategies that both are tolerant to different types of failures and lead to coordinated behavior in a multi-agent setting. This method neither relies of a centralized strategy (susceptible to single point of failures) nor a distributed strategy where each agent uses a system wide evaluation function (severe credit assignment problem). In a multi-rover problem, we show that agents using our agent-specific evaluation perform up to 500% better than agents using the system evaluation. In addition we show that agents are still able to maintain a high level of performance when up to 60% of the agents fail due to actuator, communication or controller faults.

  7. Adaptive fault-tolerant control of linear systems with actuator saturation and L2-disturbances

    Institute of Scientific and Technical Information of China (English)

    Wei GUAN; Guanghong YANG


    This paper studies the problem of designing adaptive fault-tolerant H-infinity controllers for linear timeinvariant systems with actuator saturation. The disturbance tolerance ability of the closed-loop system is measured by an optimal index. The notion of an adaptive H-infinity performance index is proposed to describe the disturbance attenuation performances of closed-loop systems. New methods for designing indirect adaptive fault-tolerant controllers via state feedback are presented for actuator fault compensations. Based on the on-line estimation of eventual faults, the adaptive fault-tolerant controller parameters are updated automatically to compensate for the fault effects on systems. The designs are developed in the framework of the linear matrix inequality (LMI) approach, which can guarantee the disturbance tolerance ability and adaptive H-infinity performances of closed-loop systems in the cases of actuator saturation and actuator failures. An example is given to illustrate the efficiency of the design method.

  8. Location and Shallow Structure of the Frijoles Strand of the San Gregorio Fault Zone, Pescadero, California (United States)

    Fox-Lent, C.; Catchings, R. D.; Rymer, M. J.; Goldman, M. R.; Steedman, C. E.; Prentice, C. S.


    The San Gregorio fault is one of the principal faults of the San Andreas fault system in the San Francisco Bay area. Located west of the active trace of the San Andreas fault and near the coast, the San Gregorio fault zone consists of at least two northwest-southeast-trending strands, the Coastways and Frijoles faults. Little is known about the slip history on the San Gregorio, and information for the Frijoles fault is especially scarce, as it lies mostly offshore. To better understand the contribution of the San Gregorio fault zone to slip along the San Andreas fault system, we conducted a high-resolution, seismic imaging investigation of the Frijoles fault to locate near-surface, onshore, branches of the fault that may be suitable for paleoseismic trenching. Our seismic survey consisted of a 590-meter-long, east-west-trending, combined seismic reflection and refraction profile across Butano Creek Valley, in Pescadero, California. The profile included 107 shot points and 120 geophones spaced at 5-m increments. Seismic sources were generated by a Betsy Seisgun in 0.3-m-deep holes. Data were recorded on two Geometrics Strataview RX-60 seismographs at a sampling rate of 0.5 ms. Seismic p-wave velocities, determined by inverting first-arrival refractions using tomographic methods, ranged from 900 m/s in the shallow subsurface to 5000 m/s at 200 m depth, with higher velocities in the western half of the profile. Migrated seismic reflection images show clear, planar layering in the top 100-200 meters on the eastern and western ends of the seismic profile. However, to within the shallow subsurface, a 200-m-long zone near the center of the profile shows disturbed stratigraphic layers with several apparent fault strands approaching within a few meters of the surface. The near-surface locations of the imaged strands suggest that the Frijoles fault has been active in the recent past, although further paleoseismic study is needed to detail the slip history of the San Gregorio

  9. Research of Multi-Agent System based satellite fault diagnosis technology

    Institute of Scientific and Technical Information of China (English)

    范显峰; 姜兴渭; 黄文虎; 谷吉海


    Following the theory of Multi-Agent System (MAS) and using series-wound structure and shunt-wound structure of Agents, the performance of Agent was improved to satisfy the need of satellite fault diagno-sis, and a tridimensional MAS model of satellite fault diagnosis was thus established for the MAS based planardiagnosis system, which decentralizes the whole diagnosing task into subtasks to be performed by different func-tional Agents to make the complicated fault diagnosis very simple and the diagnosis system more intelligent.This method improved the reliability and accuracy of diagnosis and made the maintenance and upgrading of thesatellite fault diagnosis system very easy as well.

  10. Advanced information processing system: The Army fault tolerant architecture conceptual study. Volume 2: Army fault tolerant architecture design and analysis (United States)

    Harper, R. E.; Alger, L. S.; Babikyan, C. A.; Butler, B. P.; Friend, S. A.; Ganska, R. J.; Lala, J. H.; Masotto, T. K.; Meyer, A. J.; Morton, D. P.


    Described here is the Army Fault Tolerant Architecture (AFTA) hardware architecture and components and the operating system. The architectural and operational theory of the AFTA Fault Tolerant Data Bus is discussed. The test and maintenance strategy developed for use in fielded AFTA installations is presented. An approach to be used in reducing the probability of AFTA failure due to common mode faults is described. Analytical models for AFTA performance, reliability, availability, life cycle cost, weight, power, and volume are developed. An approach is presented for using VHSIC Hardware Description Language (VHDL) to describe and design AFTA's developmental hardware. A plan is described for verifying and validating key AFTA concepts during the Dem/Val phase. Analytical models and partial mission requirements are used to generate AFTA configurations for the TF/TA/NOE and Ground Vehicle missions.

  11. Self-organized criticality of power system faults and its application in adaptation to extreme climate

    Institute of Scientific and Technical Information of China (English)

    SU Sheng; LI YinHong; DUAN XianZhong


    This paper analyzes the statistics of faults in a transmission and distribution networks in central China, unveils long-term autocorrelation and power law distribution of power system faults, which indicates that power system fault has self-organized criticality (SOC) feature. The conclusion is consistent with the power systems data in 2008 with ice storm present. Since power systems cover large areas, climate is the key factor to its safety and stability. In-depth analysis shows that the SOC of atmosphere system contributes much to that of power system faults. Extreme climate will be more intense and frequent with global warming, it will have more and more impact upon power systems. The SOC feature of power system faults is utilized to develop approaches to facilitate power systems adaptation to climate varia-tion in an economical and efficient way.

  12. Fault Feature Analysis of a Cracked Gear Coupled Rotor System

    Directory of Open Access Journals (Sweden)

    Hui Ma


    Full Text Available Considering the misalignment of gear root circle and base circle and accurate transition curve, an improved mesh stiffness model for healthy gear is proposed, and it is validated by comparison with the finite element method. On the basis of the improved method, a mesh stiffness model for a cracked gear pair is built. Then a finite element model of a cracked gear coupled rotor system in a one-stage reduction gear box is established. The effects of crack depth, width, initial position, and crack propagation direction on gear mesh stiffness, fault features in time domain and frequency domain, and statistical indicators are investigated. Moreover, fault features are also validated by experiment. The results show that the improved mesh stiffness model is more accurate than the traditional mesh stiffness model. When the tooth root crack appears, distinct impulses are found in time domain vibration responses, and sidebands appear in frequency domain. Amplitudes of all the statistical indicators ascend gradually with the growth of crack depth and width, decrease with the increasing crack initial position angle, and firstly increase and then decrease with the growth of propagation direction angle.

  13. Fault-tolerance in Two-dimensional Topological Systems (United States)

    Anderson, Jonas T.

    This thesis is a collection of ideas with the general goal of building, at least in the abstract, a local fault-tolerant quantum computer. The connection between quantum information and topology has proven to be an active area of research in several fields. The introduction of the toric code by Alexei Kitaev demonstrated the usefulness of topology for quantum memory and quantum computation. Many quantum codes used for quantum memory are modeled by spin systems on a lattice, with operators that extract syndrome information placed on vertices or faces of the lattice. It is natural to wonder whether the useful codes in such systems can be classified. This thesis presents work that leverages ideas from topology and graph theory to explore the space of such codes. Homological stabilizer codes are introduced and it is shown that, under a set of reasonable assumptions, any qubit homological stabilizer code is equivalent to either a toric code or a color code. Additionally, the toric code and the color code correspond to distinct classes of graphs. Many systems have been proposed as candidate quantum computers. It is very desirable to design quantum computing architectures with two-dimensional layouts and low complexity in parity-checking circuitry. Kitaev's surface codes provided the first example of codes satisfying this property. They provided a new route to fault tolerance with more modest overheads and thresholds approaching 1%. The recently discovered color codes share many properties with the surface codes, such as the ability to perform syndrome extraction locally in two dimensions. Some families of color codes admit a transversal implementation of the entire Clifford group. This work investigates color codes on the 4.8.8 lattice known as triangular codes. I develop a fault-tolerant error-correction strategy for these codes in which repeated syndrome measurements on this lattice generate a three-dimensional space-time combinatorial structure. I then develop an

  14. Do faults stay cool under stress? (United States)

    Savage, H. M.; Polissar, P. J.; Sheppard, R. E.; Brodsky, E. E.; Rowe, C. D.


    Determining the absolute stress on faults during slip is one of the major goals of earthquake physics as this information is necessary for full mechanical modeling of the rupture process. One indicator of absolute stress is the total energy dissipated as heat through frictional resistance. The heat results in a temperature rise on the fault that is potentially measurable and interpretable as an indicator of the absolute stress. We present a new paleothermometer for fault zones that utilizes the thermal maturity of extractable organic material to determine the maximum frictional heating experienced by the fault. Because there are no retrograde reactions in these organic systems, maximum heating is preserved. We investigate four different faults: 1) the Punchbowl Fault, a strike-slip fault that is part of the ancient San Andreas system in southern California, 2) the Muddy Mountain Thrust, a continental thrust sheet in Nevada, 3) large shear zones of Sitkanik Island, AK, part of the proto-megathrust of the Kodiak Accretionary Complex and 4) the Pasagshak Point Megathrust, Kodiak Accretionary Complex, AK. According to a variety of organic thermal maturity indices, the thermal maturity of the rocks falls within the range of heating expected from the bounds on burial depth and time, indicating that the method is robust and in some cases improving our knowledge of burial depth. Only the Pasagshak Point Thrust, which is also pseudotachylyte-bearing, shows differential heating between the fault and off-fault samples. This implies that most of the faults did not get hotter than the surrounding rock during slip. Simple temperature models coupled to the kinetic reactions for organic maturity let us constrain certain aspects of the fault during slip such as fault friction, maximum slip in a single earthquake, the thickness of the active slipping zone and the effective normal stress. Because of the significant length of these faults, we find it unlikely that they never sustained

  15. A fault tolerant superheat control strategy for supermarket refrigeration systems

    DEFF Research Database (Denmark)

    Vinther, Kasper; Izadi-Zamanabadi, Roozbeh; Rasmussen, Henrik;


    in a plug & play fashion. The strategy is outlined by means of procedural steps as well as a flow chart that also illustrates the process of automatic tuning of the maximum slope-seeking controller. Test results are furthermore presented for a display case in a full scale CO2 supermarket refrigeration......In this paper, a fault tolerant control (FTC) strategy is proposed for evaporator superheat control in supermarket refrigeration systems. Conventional control uses a pressure and temperature sensor for this purpose, however, the pressure sensor can fail to function. A contingency control strategy......, based on a maximum slope-seeking control method and only a single temperature sensor, is developed to drive the evaporator outlet temperature to a level that gives a suitable superheat of the refrigerant. The FTC strategy requires no a priori system knowledge or additional hardware and functions...

  16. Software System for Finding the Incipient Faults in Power Transformers

    Directory of Open Access Journals (Sweden)

    Nikolina Petkova


    Full Text Available In this paper a new software system for finding of incipient faultsis presented.An experiment is made with real measurement of partial discharge(PD that appeared in power transformer. The software system usesacquisition data to define the real state of this transformer. One of the most important criteria for the power transformer’s state is the presence of partial discharges. The wave propagation caused by partial discharge depends on scheme of the winding and construction of the power equipment. In all cases, the PD source had a specific position so the wave measured from the PD –coupling device had a specific waveform. The waveform is different when PDcoupling device is put on a specific place. The waveform and the time of propagation are criteria for the localization of the source of incipient faults in the volume of power transformer.

  17. Fault Diagnosis of Nonlinear Systems Based on Hybrid PSOSA Optimization Algorithm

    Institute of Scientific and Technical Information of China (English)

    Ling-Lai Li; Dong-Hua Zhou; Ling Wang


    Fault diagnosis of nonlinear systems is of great importance in theory and practice, and the parameter estimation method is an effective strategy. Based on the framework of moving horizon estimation, fault parameters are identified by a proposed intelligent optimization algorithm called PSOSA, which could avoid premature convergence of standard particle swarm optimization (PSO) by introducing the probabilistic jumping property of simulated annealing (SA). Simulations on a three-tank system show the effectiveness of this optimization based fault diagnosis strategy.

  18. Analytical Model-based Fault Detection and Isolation in Control Systems

    DEFF Research Database (Denmark)

    Vukic, Z.; Ozbolt, H.; Blanke, M.


    The paper gives an introduction and an overview of the field of fault detection and isolation for control systems. The summary of analytical (quantitative model-based) methodds and their implementation are presented. The focus is given to mthe analytical model-based fault-detection and fault...... diagnosis methods, often viewed as the classical or deterministic ones. Emphasis is placed on the algorithms suitable for ship automation, unmanned underwater vehicles, and other systems of automatic control....

  19. Passive Fault Tolerant Control of Piecewise Affine Systems Based on H Infinity Synthesis

    DEFF Research Database (Denmark)

    Gholami, Mehdi; Cocquempot, vincent; Schiøler, Henrik


    In this paper we design a passive fault tolerant controller against actuator faults for discretetime piecewise affine (PWA) systems. By using dissipativity theory and H analysis, fault tolerant state feedback controller design is expressed as a set of Linear Matrix Inequalities (LMIs). In the cur......). In the current paper, the PWA system switches not only due to the state but also due to the control input. The method is applied on a large scale livestock ventilation model....

  20. Knowledge Processing Method of Fault Diagnosis Expert Systems for Letter Sorting Equipment

    Institute of Scientific and Technical Information of China (English)


    Based on the analysis of fault diagnosis knowledge of lettersorting machine, this paper proposes a processing method by which the fault diagnosis knowledge is divided into exact knowledge, inadequate knowledge and fuzzy knowledge. Then their presenting and implementing form in fault diagnosis expert system is discussed and studied. It is proved that the expert system has good feasibility in the field of the diagnosis of letter sorting machine.

  1. The Quaternary Silver Creek Fault Beneath the Santa Clara Valley, California (United States)

    Wentworth, Carl M.; Williams, Robert A.; Jachens, Robert C.; Graymer, Russell W.; Stephenson, William J.


    The northwest-trending Silver Creek Fault is a 40-km-long strike-slip fault in the eastern Santa Clara Valley, California, that has exhibited different behaviors within a changing San Andreas Fault system over the past 10-15 Ma. Quaternary alluvium several hundred meters thick that buries the northern half of the Silver Creek Fault, and that has been sampled by drilling and imaged in a detailed seismic reflection profile, provides a record of the Quaternary history of the fault. We assemble evidence from areal geology, stratigraphy, paleomagnetics, ground-water hydrology, potential-field geophysics, and reflection and earthquake seismology to determine the long history of the fault in order to evaluate its current behavior. The fault formed in the Miocene more than 100 km to the southeast, as the southwestern fault in a 5-km-wide right step to the Hayward Fault, within which the 40-km-long Evergreen pull-apart basin formed. Later, this basin was obliquely cut by the newly recognized Mt. Misery Fault to form a more direct connection to the Hayward Fault, although continued growth of the basin was sufficient to accommodate at least some late Pliocene alluvium. Large offset along the San Andreas-Calaveras-Mt Misery-Hayward Faults carried the basin northwestward almost to its present position when, about 2 Ma, the fault system was reorganized. This led to near abandonment of the faults bounding the pull-apart basin in favor of right slip extending the Calaveras Fault farther north before stepping west to the Hayward Fault, as it does today. Despite these changes, the Silver Creek Fault experienced a further 200 m of dip slip in the early Quaternary, from which we infer an associated 1.6 km or so of right slip, based on the ratio of the 40-km length of the strike-slip fault to a 5-km depth of the Evergreen Basin. This dip slip ends at a mid-Quaternary unconformity, above which the upper 300 m of alluvial cover exhibits a structural sag at the fault that we interpret as

  2. Minimum Error Entropy Filter for Fault Detection of Networked Control Systems


    Guolian Hou; Mifeng Ren; Lilong Du; Jianhua Zhang


    In this paper, fault detection of networked control systems with random delays, packet dropout and noises is studied. The filter is designed using a minimum error entropy criterion. The residual generated by the filter is then evaluated to detect faults in networked control systems. An illustrative networked control system is used to verify the effectiveness of the proposed approach.

  3. Minimum Error Entropy Filter for Fault Detection of Networked Control Systems

    Directory of Open Access Journals (Sweden)

    Guolian Hou


    Full Text Available In this paper, fault detection of networked control systems with random delays, packet dropout and noises is studied. The filter is designed using a minimum error entropy criterion. The residual generated by the filter is then evaluated to detect faults in networked control systems. An illustrative networked control system is used to verify the effectiveness of the proposed approach.

  4. Fault Detection, Isolation, and Accommodation for LTI Systems Based on GIMC Structure

    Directory of Open Access Journals (Sweden)

    D. U. Campos-Delgado


    Full Text Available In this contribution, an active fault-tolerant scheme that achieves fault detection, isolation, and accommodation is developed for LTI systems. Faults and perturbations are considered as additive signals that modify the state or output equations. The accommodation scheme is based on the generalized internal model control architecture recently proposed for fault-tolerant control. In order to improve the performance after a fault, the compensation is considered in two steps according with a fault detection and isolation algorithm. After a fault scenario is detected, a general fault compensator is activated. Finally, once the fault is isolated, a specific compensator is introduced. In this setup, multiple faults could be treated simultaneously since their effect is additive. Design strategies for a nominal condition and under model uncertainty are presented in the paper. In addition, performance indices are also introduced to evaluate the resulting fault-tolerant scheme for detection, isolation, and accommodation. Hard thresholds are suggested for detection and isolation purposes, meanwhile, adaptive ones are considered under model uncertainty to reduce the conservativeness. A complete simulation evaluation is carried out for a DC motor setup.

  5. Simultaneous-Fault Diagnosis of Gas Turbine Generator Systems Using a Pairwise-Coupled Probabilistic Classifier

    Directory of Open Access Journals (Sweden)

    Zhixin Yang


    Full Text Available A reliable fault diagnostic system for gas turbine generator system (GTGS, which is complicated and inherent with many types of component faults, is essential to avoid the interruption of electricity supply. However, the GTGS diagnosis faces challenges in terms of the existence of simultaneous-fault diagnosis and high cost in acquiring the exponentially increased simultaneous-fault vibration signals for constructing the diagnostic system. This research proposes a new diagnostic framework combining feature extraction, pairwise-coupled probabilistic classifier, and decision threshold optimization. The feature extraction module adopts wavelet packet transform and time-domain statistical features to extract vibration signal features. Kernel principal component analysis is then applied to further reduce the redundant features. The features of single faults in a simultaneous-fault pattern are extracted and then detected using a probabilistic classifier, namely, pairwise-coupled relevance vector machine, which is trained with single-fault patterns only. Therefore, the training dataset of simultaneous-fault patterns is unnecessary. To optimize the decision threshold, this research proposes to use grid search method which can ensure a global solution as compared with traditional computational intelligence techniques. Experimental results show that the proposed framework performs well for both single-fault and simultaneous-fault diagnosis and is superior to the frameworks without feature extraction and pairwise coupling.

  6. Accurate one-end fault location for overhead transmission lines in interconnected power systems

    Energy Technology Data Exchange (ETDEWEB)

    Eisa, Amir A.A.; Ramar, K. [Faculty of Engineering, Multimedia University, 63100 Cyberjaya (Malaysia)


    This paper presents a new one-end fault location method for overhead transmission lines embedded in a general n-bus interconnected power system. High accuracy in fault location is achieved by using both an accurate distributed parameters model for the faulted transmission line, and a two-bus Thevenin equivalent network model for the power system that accurately accounts for its interconnectivity. The method has been tested using transient fault data obtained from PSCAD/EMTDC simulations of an 11-bus interconnected power system. The results obtained indicate that the method is capable of estimating the fault distance with high accuracy for various fault conditions. They also indicate that method is sensitive to errors in the value of the local bus impedance, but is insensitive to errors in the value of the remote bus impedance. (author)

  7. An Ontology for Identifying Cyber Intrusion Induced Faults in Process Control Systems (United States)

    Hieb, Jeffrey; Graham, James; Guan, Jian

    This paper presents an ontological framework that permits formal representations of process control systems, including elements of the process being controlled and the control system itself. A fault diagnosis algorithm based on the ontological model is also presented. The algorithm can identify traditional process elements as well as control system elements (e.g., IP network and SCADA protocol) as fault sources. When these elements are identified as a likely fault source, the possibility exists that the process fault is induced by a cyber intrusion. A laboratory-scale distillation column is used to illustrate the model and the algorithm. Coupled with a well-defined statistical process model, this fault diagnosis approach provides cyber security enhanced fault diagnosis information to plant operators and can help identify that a cyber attack is underway before a major process failure is experienced.

  8. Fault Detection and Isolation for a Supermarket Refrigeration System - Part One

    DEFF Research Database (Denmark)

    Yang, Zhenyu; Rasmussen, Karsten B.; Kieu, Anh T.;


    Fault Detection and Isolation (FDI) using the Kalman Filter (KF) technique for a supermarket refrigeration system is explored. Four types of sensor fault scenarios, namely drift, offset, freeze and hard-over, are considered for two temperature sensors, and one type of parametric fault scenario, n....... The test results show that the EKF-based FDI method generally performances better and faster than the KF-based method does. However, both methods can not handle the isolation between sensor faults and parametric fault.......Fault Detection and Isolation (FDI) using the Kalman Filter (KF) technique for a supermarket refrigeration system is explored. Four types of sensor fault scenarios, namely drift, offset, freeze and hard-over, are considered for two temperature sensors, and one type of parametric fault scenario...... isolation purpose, a bank of KFs arranged by splitting measurements is constructed for sensor fault isolation, while the Multi-Model Adaptive Estimation (MMAE) method is employed to handle parametric fault isolation. All these approaches are extended and checked by using Extended KF technique afterwards...

  9. From tomographic images to fault heterogeneities

    Directory of Open Access Journals (Sweden)

    A. Amato


    Full Text Available Local Earthquake Tomography (LET is a useful tool for imaging lateral heterogeneities in the upper crust. The pattern of P- and S-wave velocity anomalies, in relation to the seismicity distribution along active fault zones. can shed light on the existence of discrete seismogenic patches. Recent tomographic studies in well monitored seismic areas have shown that the regions with large seismic moment release generally correspond to high velocity zones (HVZ's. In this paper, we discuss the relationship between the seismogenic behavior of faults and the velocity structure of fault zones as inferred from seismic tomography. First, we review some recent tomographic studies in active strike-slip faults. We show examples from different segments of the San Andreas fault system (Parkfield, Loma Prieta, where detailed studies have been carried out in recent years. We also show two applications of LET to thrust faults (Coalinga, Friuli. Then, we focus on the Irpinia normal fault zone (South-Central Italy, where a Ms = 6.9 earthquake occurred in 1980 and many thousands of attershock travel time data are available. We find that earthquake hypocenters concentrate in HVZ's, whereas low velocity zones (LVZ’ s appear to be relatively aseismic. The main HVZ's along which the mainshock rupture bas propagated may correspond to velocity weakening fault regions, whereas the LVZ's are probably related to weak materials undergoing stable slip (velocity strengthening. A correlation exists between this HVZ and the area with larger coseismic slip along the fault, according to both surface evidence (a fault scarp as high as 1 m and strong ground motion waveform modeling. Smaller wave-length, low-velocity anomalies detected along the fault may be the expression of velocity strengthening sections, where aseismic slip occurs. According to our results, the rupture at the nucleation depth (~ 10-12 km is continuous for the whole fault lenoth (~ 30 km, whereas at shallow depth

  10. Sensor scheduling strategies for fault isolation in networked control system. (United States)

    Sid, M A


    A framework for the joint design of sensor scheduling and fault isolation is proposed. First, the synthesis of fault isolation filter and the communication sequence that ensures the isolability of fault is given. The proposed filter can be viewed as a special structure of the traditional Kalman filter. Several sensor scheduling strategies are proposed in order to ensure the minimization of the noise effect on the generated residual. A numerical example illustrates the effectiveness of the proposed approach.

  11. Sensor Fault Masking of a Ship Propulsion System

    DEFF Research Database (Denmark)

    Wu, N. Eva; Thavamani, Shuda; Zhang, Youmin


    This paper presents the results of a study on fault-tolerant control of a ship propulsion benchmark (Izadi-Zamanabadi and Blanke, 999), which uses estimated or virtual measurements as feedback variables. The estimator operates on a self-adjustable design model so that its outputs can be made immune...... that are captured in the estimator's design model can be tolerated without the need for any recon¯guration actions. Simulations for the ship propulsion benchmark show that, with additional sensors added as described, satisfactory fault-tolerance is achieved under two additive sensor faults, an incipient fault...

  12. Sensor Fault Masking of a Ship Propulsion System

    DEFF Research Database (Denmark)

    Wu, N.E.; Thavamani, A.; Zhang, Y.


    This paper presents the results of a study on fault-tolerant control of a ship propulsion benchmark (Izadi-Zamanabadi and Blanke, 1999), which uses estimated or virtual measurements as feedback variables. The estimator operates on a selfadjustable design model so that its outputs can be made immune...... that are captured in the estimator's design model can be tolerated without the need for any reconfiguration actions. Simulations for the ship propulsion benchmark show that, with additional sensors added as described, satisfactory fault-tolerance is achieved under two additive sensor faults, an incipient fault...

  13. Sensor Fault Diagnosis for a Class of Time Delay Uncertain Nonlinear Systems Using Neural Network

    Institute of Scientific and Technical Information of China (English)

    Mou Chen; Chang-Sheng Jiang; Qing-Xian Wu


    In this paper, a sliding mode observer scheme of sensor fault diagnosis is proposed for a class of time delay nonlinear systems with input uncertainty based on neural network. The sensor fault and the system input uncertainty are assumed to be unknown but bounded. The radial basis function (RBF) neural network is used to approximate the sensor fault. Based on the output of the RBF neural network, the sliding mode observer is presented. Using the Lyapunov method, a criterion for stability is given in terms of matrix inequality. Finally, an example is given for illustrating the availability of the fault diagnosis based on the proposed sliding mode observer.

  14. Novel active fault-tolerant control scheme and its application to a double inverted pendulum system

    Institute of Scientific and Technical Information of China (English)


    On the basis of the gain-scheduled H∞ design strategy,a novel active fault-tolerant control scheme is proposed.Under the assumption that the effects of faults on the state-space matrices of systems can be of affine parameter dependence,a reconfigurable robust H∞ linear parameter varying controller is developed.The designed controller is a function of the fault effect factors that can be derived online by using a well-trained neural network.To demonstrate the effectiveness of the proposed method,a double inverted pendulum system,with a fault in the motor tachometer loop,is considered.

  15. Neural adaptive observer-based sensor and actuator fault detection in nonlinear systems: Application in UAV. (United States)

    Abbaspour, Alireza; Aboutalebi, Payam; Yen, Kang K; Sargolzaei, Arman


    A new online detection strategy is developed to detect faults in sensors and actuators of unmanned aerial vehicle (UAV) systems. In this design, the weighting parameters of the Neural Network (NN) are updated by using the Extended Kalman Filter (EKF). Online adaptation of these weighting parameters helps to detect abrupt, intermittent, and incipient faults accurately. We apply the proposed fault detection system to a nonlinear dynamic model of the WVU YF-22 unmanned aircraft for its evaluation. The simulation results show that the new method has better performance in comparison with conventional recurrent neural network-based fault detection strategies.

  16. Discrete wavelet transform-based fault diagnosis for driving system of pipeline detection robot arm

    Institute of Scientific and Technical Information of China (English)

    Deng Huiyu; Wang Xinli; Ma Peisun


    A real-time wavelet multi-resolution analysis (MRA)-based fault detection algorithm is proposed. The first stage detailed MRA signals extracted from the original signals were used as the criteria for fault detection. By measuring sharp variations in the detailed MRA signals, faults in the motor driving system of pipeline detection robot arm could be detected. The fault type was then identified by comparison of the three-phase MRA sharp variations. The effects of the faults were examined. The simulation results show that this algorithm is effective and robust, it is promising for fault detection in a robot's joint driving system. The method is simple, rapid and it can operate in real time.

  17. Design of H(infinity) robust fault detection filter for linear uncertain time-delay systems. (United States)

    Bai, Leishi; Tian, Zuohua; Shi, Songjiao


    In this paper, the robust fault detection filter design problem for linear time-delay systems with both unknown inputs and parameter uncertainties is studied. Using a multiobjective optimization technique, a new performance index is introduced, which takes into account the robustness of the fault detection filter against disturbances and sensitivity to faults simultaneously. The reference residual model is then designed based on this performance index to formulate the robust fault detection filter design problem as an H(infinity) model-matching problem. By applying robust H(infinity) optimization control technique, the existence condition of the robust fault detection filter for linear time-delay systems with both unknown inputs and parameter uncertainties is presented in terms of linear matrix inequality formulation, independently of time delay. In order to detect the fault, an adaptive threshold which depends on the inputs is finally determined. An illustrative design example is used to demonstrate the validity of the proposed approach.

  18. Investigating fault coupling: Creep and microseismicity on the Hayward fault (United States)

    Evans, E. L.; Loveless, J. P.; Meade, B. J.; Burgmann, R.


    We seek to quantify the relationship between interseismic slip activity and microseismicity along the Hayward fault in the eastern San Francisco Bay Area. During the interseismic regime the Hayward fault is known to exhibit variable degrees of locking both along strike and down-dip. Background microseismicity on and near the fault has been suggested to provide independent information about the rates of interseismic creep and the boundaries of creeping regions. In particular, repeating earthquakes within the fault zone have been suggested as a proxy for fault creep rates. To investigate this relationship, we invert GPS data for microplate rotations, fault slip rates, and fault coupling using a block model that spans western United States and includes the San Andreas, Hayward, Calaveras, Rogers Creek, and Green Valley faults in the greater Bay area. The tectonic context provided by the regional scale model ensures that the slip budget across Bay Area faults is consistent with large scale tectonic motions and kinematically connected to the central San Andreas fault. We image the spatial distribution of interseismic slip on a triangulated mesh of the Hayward fault and compare the distribution of interseismic fault coupling with the number of earthquakes and the moment rate of all on-fault seismicity. We quantitatively test the hypothesis that microseismicity might define the transitions between locked and creeping regions. The calculated correlations are tested against a null hypothesis that microseismicity is randomly distributed. We further extend this investigation to the step over region between the Hayward and Calaveras faults to illuminate the interactions between linking faults.

  19. A fault diagnosis system for PV power station based on global partitioned gradually approximation method (United States)

    Wang, S.; Zhang, X. N.; Gao, D. D.; Liu, H. X.; Ye, J.; Li, L. R.


    As the solar photovoltaic (PV) power is applied extensively, more attentions are paid to the maintenance and fault diagnosis of PV power plants. Based on analysis of the structure of PV power station, the global partitioned gradually approximation method is proposed as a fault diagnosis algorithm to determine and locate the fault of PV panels. The PV array is divided into 16x16 blocks and numbered. On the basis of modularly processing of the PV array, the current values of each block are analyzed. The mean current value of each block is used for calculating the fault weigh factor. The fault threshold is defined to determine the fault, and the shade is considered to reduce the probability of misjudgments. A fault diagnosis system is designed and implemented with LabVIEW. And it has some functions including the data realtime display, online check, statistics, real-time prediction and fault diagnosis. Through the data from PV plants, the algorithm is verified. The results show that the fault diagnosis results are accurate, and the system works well. The validity and the possibility of the system are verified by the results as well. The developed system will be benefit for the maintenance and management of large scale PV array.

  20. A discrete event systems approach to discriminating intermittent from permanent faults

    Directory of Open Access Journals (Sweden)

    Deng Guanqian


    Full Text Available Almost all work on model-based diagnosis (MBD potentially presumes faults are persistent and does not take intermittent faults (IFs into account. Therefore, it is common for diagnosis systems to misjudge IFs as permanent faults (PFs, which are the major cause of the problems of false alarms, cannot duplication and no fault found in aircraft avionics. To address this problem, a new fault model which includes PFs and IFs is presented based on discrete event systems (DESs. Thereafter, an approach is given to discriminate between PFs and IFs by diagnosing the current fault. In this paper, the regulations of (PFs and IFs fault evolution through fault and reset events along the traces of system are studied, and then label propagation function is modified to account for PFs and the dynamic behavior of IFs and diagnosability of PFs and IFs are defined. Finally, illustrative examples are presented to demonstrate the proposed approach, and the analysis results show the fault types can be discriminated within bounded delay if the system is diagnosable.

  1. Orion GN&C Fault Management System Verification: Scope And Methodology (United States)

    Brown, Denise; Weiler, David; Flanary, Ronald


    In order to ensure long-term ability to meet mission goals and to provide for the safety of the public, ground personnel, and any crew members, nearly all spacecraft include a fault management (FM) system. For a manned vehicle such as Orion, the safety of the crew is of paramount importance. The goal of the Orion Guidance, Navigation and Control (GN&C) fault management system is to detect, isolate, and respond to faults before they can result in harm to the human crew or loss of the spacecraft. Verification of fault management/fault protection capability is challenging due to the large number of possible faults in a complex spacecraft, the inherent unpredictability of faults, the complexity of interactions among the various spacecraft components, and the inability to easily quantify human reactions to failure scenarios. The Orion GN&C Fault Detection, Isolation, and Recovery (FDIR) team has developed a methodology for bounding the scope of FM system verification while ensuring sufficient coverage of the failure space and providing high confidence that the fault management system meets all safety requirements. The methodology utilizes a swarm search algorithm to identify failure cases that can result in catastrophic loss of the crew or the vehicle and rare event sequential Monte Carlo to verify safety and FDIR performance requirements.

  2. Award ER25750: Coordinated Infrastructure for Fault Tolerance Systems Indiana University Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Lumsdaine, Andrew


    The main purpose of the Coordinated Infrastructure for Fault Tolerance in Systems initiative has been to conduct research with a goal of providing end-to-end fault tolerance on a systemwide basis for applications and other system software. While fault tolerance has been an integral part of most high-performance computing (HPC) system software developed over the past decade, it has been treated mostly as a collection of isolated stovepipes. Visibility and response to faults has typically been limited to the particular hardware and software subsystems in which they are initially observed. Little fault information is shared across subsystems, allowing little flexibility or control on a system-wide basis, making it practically impossible to provide cohesive end-to-end fault tolerance in support of scientific applications. As an example, consider faults such as communication link failures that can be seen by a network library but are not directly visible to the job scheduler, or consider faults related to node failures that can be detected by system monitoring software but are not inherently visible to the resource manager. If information about such faults could be shared by the network libraries or monitoring software, then other system software, such as a resource manager or job scheduler, could ensure that failed nodes or failed network links were excluded from further job allocations and that further diagnosis could be performed. As a founding member and one of the lead developers of the Open MPI project, our efforts over the course of this project have been focused on making Open MPI more robust to failures by supporting various fault tolerance techniques, and using fault information exchange and coordination between MPI and the HPC system software stack from the application, numeric libraries, and programming language runtime to other common system components such as jobs schedulers, resource managers, and monitoring tools.

  3. Emergency control of unstable behavior of nonlinear systems induced by fault

    Directory of Open Access Journals (Sweden)

    Mark A. Pinsky


    -functions significantly simplifying analysis and control of fault phenomena. The design of an mergency controller is based on the technique for computing fault-induced jumps of the system states, which is described in the paper. An emergency controller instantaneously returning states of a sample nonlinear system to its stability basin is designed.

  4. A Fault Diagnosis Expert System for a Heavy Motor Used in a Rolling Mill

    Institute of Scientific and Technical Information of China (English)


    A fault diagnosis expert system for a heavy motor used in a rolling mill is established in this paper. The fault diagnosis knowledge base was built, and its knowledge was represented by production rules. The knowledge base includes daily inspection system, brief diagnosis system and precise diagnosis system. A pull-down menu was adopted for the management of the knowledge base. The system can run under the help of expert system development tools. Practical examples show that the expert system can diagnose faults rapidly and precisely.

  5. Fault diagnosis in neutral point indirectly grounded system based on information fusion

    Institute of Scientific and Technical Information of China (English)

    于飞; 鞠丽叶; 刘喜梅; 崔平远; 钟秋海


    In neutral point indirectly grounded systems, phase-to-ground fault is putting new demands on fault diagnosis technology. Information fusion is applied to detect the phase-to-ground fault, which integrates several sources of information, including line current, line voltage, zero sequence current and voltage, and quintic harmonic wave component. This method is testified through the simulation of Matlab. Simulation results show that the precision and reliability of the detection has been greatly increased.

  6. Simultaneous state and actuator fault estimation for satellite attitude control systems

    Institute of Scientific and Technical Information of China (English)

    Cheng Yao; Wang Rixin; Xu Minqiang; Li Yuqing


    In this paper, a new nonlinear augmented observer is proposed and applied to satellite attitude control systems. The observer can estimate system state and actuator fault simultaneously. It can enhance the performances of rapidly-varying faults estimation. Only original system matrices are adopted in the parameter design. The considered faults can be unbounded, and the proposed augmented observer can estimate a large class of faults. Systems without disturbances and the fault whose finite times derivatives are zero piecewise are initially considered, followed by a discussion of a general situation where the system is subject to disturbances and the finite times derivatives of the faults are not null but bounded. For the considered nonlinear system, convergence conditions of the observer are provided and the stability analysis is performed using Lyapunov direct method. Then a feasible algorithm is explored to compute the observer parameters using linear matrix inequalities (LMIs). Finally, the effectiveness of the proposed approach is illustrated by considering an example of a closed-loop satellite attitude control system. The simulation results show satisfactory perfor-mance in estimating states and actuator faults. It also shows that multiple faults can be estimated successfully.

  7. Design of a real-time fault diagnosis expert system for the EAST cryoplant

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Zhiwei, E-mail: [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui (China); Zhuang Ming, E-mail: [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui (China); Lu Xiaofei, E-mail: [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui (China); Hu Liangbing, E-mail: [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui (China); Xia Genhai, E-mail: [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui (China)


    Highlights: Black-Right-Pointing-Pointer An expert system of real-time fault diagnosis for EAST cryoplant is designed. Black-Right-Pointing-Pointer Knowledge base is built via fault tree analysis based on our fault experience. Black-Right-Pointing-Pointer It can make up the deficiency of safety monitoring in cryogenic DCS. Black-Right-Pointing-Pointer It can help operators to find the fault causes and give operation suggestion. Black-Right-Pointing-Pointer It plays a role of operators training in certain degree. - Abstract: The EAST cryoplant consists of a 2 kW/4 K helium refrigerator and a helium distribution system. It is a complex process system which involves many process variables and cryogenic equipments. Each potential fault or abnormal event may influence stability and safety of the cryogenic system, thereby disturbing the fusion experiment. The cryogenic control system can monitor the process data and detect process alarms, but it is difficult to effectively diagnose the fault causes and provide operation suggestions to operators when anomalies occur. Therefore, a real-time fault diagnosis expert system is essential for a safe and steady operation of EAST cryogenic system. After a brief description of the EAST cryoplant and its control system, the structure design of the cryogenic fault diagnosis expert system is proposed. Based on the empirical knowledge, the fault diagnosis model is built adopting fault tree analysis method which considers the uncertainty. The knowledge base and the inference machine are presented in detail. A cross-platform integrated development environment Qt Creator and MySQL database have been used to develop the system. The proposed expert system has a fine graphic user interface for monitoring and operation. Preliminary test was conducted and the results found to be satisfactory.

  8. Fault Detection and Isolation of Wind Energy Conversion Systems using Recurrent Neural Networks

    Directory of Open Access Journals (Sweden)

    N. Talebi


    Full Text Available Reliability of Wind Energy Conversion Systems (WECSs is greatly important regarding to extract the maximum amount of available wind energy. In order to accurately study WECSs during occurrence of faults and to explore the impact of faults on each component of WECSs, a detailed model is required in which mechanical and electrical parts of WECSs are properly involved. In addition, a Fault Detection and Isolation System (FDIS is required by which occurred faults can be diagnosed at the appropriate time in order to ensure safe system operation and avoid heavy economic losses. This can be performed by subsequent actions through fast and accurate detection and isolation of faults. In this paper, by utilizing a comprehensive dynamic model of the WECS, an FDIS is presented using dynamic recurrent neural networks. In industrial processes, dynamic neural networks are known as a good mathematical tool for fault detection. Simulation results show that the proposed FDIS detects faults of the generator's angular velocity sensor, pitch angle sensors and pitch actuators appropriately. The suggested FDIS is capable to detect and isolate the faults shortly while owing very low false alarms rate. The presented FDIS scheme can be used to identify faults in other parts of the WECS.

  9. Fault isolation filter for networked control system with event-triggered sampling scheme. (United States)

    Li, Shanbin; Sauter, Dominique; Xu, Bugong


    In this paper, the sensor data is transmitted only when the absolute value of difference between the current sensor value and the previously transmitted one is greater than the given threshold value. Based on this send-on-delta scheme which is one of the event-triggered sampling strategies, a modified fault isolation filter for a discrete-time networked control system with multiple faults is then implemented by a particular form of the Kalman filter. The proposed fault isolation filter improves the resource utilization with graceful fault estimation performance degradation. An illustrative example is given to show the efficiency of the proposed method.

  10. Fault Isolation Filter for Networked Control System with Event-Triggered Sampling Scheme

    Directory of Open Access Journals (Sweden)

    Bugong Xu


    Full Text Available In this paper, the sensor data is transmitted only when the absolute value of difference between the current sensor value and the previously transmitted one is greater than the given threshold value. Based on this send-on-delta scheme which is one of the event-triggered sampling strategies, a modified fault isolation filter for a discrete-time networked control system with multiple faults is then implemented by a particular form of the Kalman filter. The proposed fault isolation filter improves the resource utilization with graceful fault estimation performance degradation. An illustrative example is given to show the efficiency of the proposed method.

  11. A Grid Voltage Measurement Method for Wind Power Systems during Grid Fault Conditions

    Directory of Open Access Journals (Sweden)

    Cheol-Hee Yoo


    Full Text Available Grid codes in many countries require low-voltage ride-through (LVRT capability to maintain power system stability and reliability during grid fault conditions. To meet the LVRT requirement, wind power systems must stay connected to the grid and also supply reactive currents to the grid to support the recovery from fault voltages. This paper presents a new fault detection method and inverter control scheme to improve the LVRT capability for full-scale permanent magnet synchronous generator (PMSG wind power systems. Fast fault detection can help the wind power systems maintain the DC-link voltage in a safe region. The proposed fault detection method is based on on-line adaptive parameter estimation. The performance of the proposed method is verified in comparison to the conventional voltage measurement method defined in the IEC 61400-21 standard.

  12. Remote Fault Information Acquisition and Diagnosis System of the Combine Harvester Based on LabVIEW (United States)

    Chen, Jin; Wu, Pei; Xu, Kai

    Most combine harvesters have not be equipped with online fault diagnosis system. A fault information acquisition and diagnosis system of the Combine Harvester based on LabVIEW is designed, researched and developed. Using ARM development board, by collecting many sensors' signals, this system can achieve real-time measurement, collection, displaying and analysis of different parts of combine harvesters. It can also realize detection online of forward velocity, roller speed, engine temperature, etc. Meanwhile the system can judge the fault location. A new database function is added so that we can search the remedial measures to solve the faults and also we can add new faults to the database. So it is easy to take precautions against before the combine harvester breaking down then take measures to service the harvester.

  13. Analysis and optimization of fault-tolerant embedded systems with hardened processors

    DEFF Research Database (Denmark)

    Izosimov, Viacheslav; Polian, Ilia; Pop, Paul


    In this paper we propose an approach to the design optimization of fault-tolerant hard real-time embedded systems, which combines hardware and software fault tolerance techniques. We trade-off between selective hardening in hardware and process reexecution in software to provide the required levels...... of fault tolerance against transient faults with the lowest-possible system costs. We propose a system failure probability (SFP) analysis that connects the hardening level with the maximum number of reexecutions in software. We present design optimization heuristics, to select the fault......-tolerant architecture and decide process mapping such that the system cost is minimized, deadlines are satisfied, and the reliability requirements are fulfilled....

  14. Dynamic Reconstruction-Based Fuzzy Neural Network Method for Fault Detection in Chaotic System

    Institute of Scientific and Technical Information of China (English)

    YANG Hongying; YE Hao; WANG Guizeng


    This paper presents a method for detecting weak fault signals in chaotic systems based on the chaotic dynamics reconstruction technique and the fuzzy neural system (FNS). The Grassberger-Procaccia algorithm and least squares regression were used to calculate the correlation dimension for the model order estimate. Based on the model order, an appropriately structured FNS model was designed to predict system faults. Through reasonable analysis of predicted errors, the disturbed signal can be extracted efficiently and correctly from the chaotic background. Satisfactory results were obtained by using several kinds of simula-tive faults which were extracted from the practical chaotic fault systems. Experimental results demonstra tethat the proposed approach has good prediction accuracy and can deal with data having a -40 dB signal to noise ratio (SNR). The low SNR requirement makes the approach a powerful tool for early fault detection.

  15. A real-time fault diagnosis methodology of complex systems using object-oriented Bayesian networks (United States)

    Cai, Baoping; Liu, Hanlin; Xie, Min


    Bayesian network (BN) is a commonly used tool in probabilistic reasoning of uncertainty in industrial processes, but it requires modeling of large and complex systems, in situations such as fault diagnosis and reliability evaluation. Motivated by reduction of the overall complexities of BNs for fault diagnosis, and the reporting of faults that immediately occur, a real-time fault diagnosis methodology of complex systems with repetitive structures is proposed using object-oriented Bayesian networks (OOBNs). The modeling methodology consists of two main phases: an off-line OOBN construction phase and an on-line fault diagnosis phase. In the off-line phase, sensor historical data and expert knowledge are collected and processed to determine the faults and symptoms, and OOBN-based fault diagnosis models are developed subsequently. In the on-line phase, operator experience and sensor real-time data are placed in the OOBNs to perform the fault diagnosis. According to engineering experience, the judgment rules are defined to obtain the fault diagnosis results.

  16. Research into a distributed fault diagnosis system and its application (United States)

    Qian, Suxiang; Jiao, Weidong; Lou, Yongjian; Shen, Xiaomei


    CORBA (Common Object Request Broker Architecture) is a solution to distributed computing methods over heterogeneity systems, which establishes a communication protocol between distributed objects. It takes great emphasis on realizing the interoperation between distributed objects. However, only after developing some application approaches and some practical technology in monitoring and diagnosis, can the customers share the monitoring and diagnosis information, so that the purpose of realizing remote multi-expert cooperation diagnosis online can be achieved. This paper aims at building an open fault monitoring and diagnosis platform combining CORBA, Web and agent. Heterogeneity diagnosis object interoperate in independent thread through the CORBA (soft-bus), realizing sharing resource and multi-expert cooperation diagnosis online, solving the disadvantage such as lack of diagnosis knowledge, oneness of diagnosis technique and imperfectness of analysis function, so that more complicated and further diagnosis can be carried on. Take high-speed centrifugal air compressor set for example, we demonstrate a distributed diagnosis based on CORBA. It proves that we can find out more efficient approaches to settle the problems such as real-time monitoring and diagnosis on the net and the break-up of complicated tasks, inosculating CORBA, Web technique and agent frame model to carry on complemental research. In this system, Multi-diagnosis Intelligent Agent helps improve diagnosis efficiency. Besides, this system offers an open circumstances, which is easy for the diagnosis objects to upgrade and for new diagnosis server objects to join in.

  17. Sankt Andreas Kirke 1873-1998

    DEFF Research Database (Denmark)

    Olden-Jørgensen, Sebastian

    Den katolske Sankt Andreas Kirkes (Ordrup) historie med særlig vægt på bygningshistorien og det kulturelle liv omkring kirken, hvor både jesuitter, dominikanere og verdenspræster har virket.......Den katolske Sankt Andreas Kirkes (Ordrup) historie med særlig vægt på bygningshistorien og det kulturelle liv omkring kirken, hvor både jesuitter, dominikanere og verdenspræster har virket....

  18. Fault-Tolerant Control of the Road Wheel Subsystem in a Steer-By-Wire System

    Directory of Open Access Journals (Sweden)

    Bing Zheng


    Full Text Available This paper describes a fault-tolerant steer-by-wire road wheel control system. With dual motor and dual microcontroller architecture, this system has the capability to tolerate single-point failures without degrading the control system performance. The arbitration bus, mechanical arrangement of motors, and the developed control algorithm allow the system to reconfigure itself automatically in the event of a single-point fault, and assure a smooth reconfiguration process. Both simulation and experimental results illustrate the effectiveness of the proposed fault-tolerant control system.

  19. Geologic map of the Hayward fault zone, Contra Costa, Alameda, and Santa Clara counties, California: a digital database (United States)

    Graymer, R.W.; Jones, D.L.; Brabb, E.E.


    The Hayward is one of three major fault zones of the San Andreas system that have produced large historic earthquakes in the San Francisco Bay Area (the others being the San Andreas and Calaveras). Severe earthquakes were generated by this fault zone in 1836 and in 1868, and several large earthquakes have been recorded since 1868. The Hayward fault zone is considered to be the most probable source of a major earthquake in the San Francisco Bay Area, as much as 28% chance for a magnitude 7 earthquake before the year 2021 (Working Group on California Earthquake Probabilities, 1990). The Hayward fault zone, as described in this work, is a zone of highly deformed rocks, trending north 30 degrees west and ranging in width from about 2 to 10 kilometers. The historic earthquake generating activity has been concentrated in the western portion of the zone, but the zone as a whole reflects deformation derived from oblique right-lateral and compressive tectonic stress along a significant upper crustal discontinuity for the past 10 million or more years. The Hayward fault zone is bounded on the east by a series of faults that demarcate the beginning of one or more structural blocks containing rocks and structures unrelated to the Hayward fault zone. The eastern bounding faults are, from the south, the Calaveras, Stonybrook, Palomares, Miller Creek, and Moraga faults. These faults are not considered to be part of the Hayward fault zone, although they are shown on the map to demarcate its boundary. The western boundary of the zone is less clearly defined, because the alluvium of the San Francisco Bay and Santa Clara Valley basins obscures bedrock and structural relationships. Although several of the westernmost faults in the zone clearly project under or through the alluvium, the western boundary of the fault is generally considered to be the westernmost mapped fault, which corresponds more or less with the margin of thick unconsolidated surficial deposits. The Hayward fault

  20. Constraining the kinematics of metropolitan Los Angeles faults with a slip-partitioning model (United States)

    Daout, S.; Barbot, S.; Peltzer, G.; Doin, M.-P.; Liu, Z.; Jolivet, R.


    Due to the limited resolution at depth of geodetic and other geophysical data, the geometry and the loading rate of the ramp-décollement faults below the metropolitan Los Angeles are poorly understood. Here we complement these data by assuming conservation of motion across the Big Bend of the San Andreas Fault. Using a Bayesian approach, we constrain the geometry of the ramp-décollement system from the Mojave block to Los Angeles and propose a partitioning of the convergence with 25.5 ± 0.5 mm/yr and 3.1 ± 0.6 mm/yr of strike-slip motion along the San Andreas Fault and the Whittier Fault, with 2.7 ± 0.9 mm/yr and 2.5 ± 1.0 mm/yr of updip movement along the Sierra Madre and the Puente Hills thrusts. Incorporating conservation of motion in geodetic models of strain accumulation reduces the number of free parameters and constitutes a useful methodology to estimate the tectonic loading and seismic potential of buried fault networks.

  1. Fault-Tolerant Design and Testing of USB2.0 Peripheral Devices IP Core System

    Institute of Scientific and Technical Information of China (English)

    BAI Xiaoping; WEI Yuanfeng


    Universal serial bus 2.0 (USB2.0) is a kind of mainstream interface technology. The traditional USB developing is only to develop USB peripheral devices. For the USB2.0 peripheral devices IP core system that has wide application foreground, some interference inevitably exists in signal transmitting. Some fault-tolerant design and test methods must be adopted in order to correctly transmit and receive data. Combining with a project, this paper introduces in detail about measures, hardware implement, and test methods of fault-tolerant design about USB2.0 peripheral devices IP core system. Fault-tolerant design measures, noise reduction measures of signal processing, fault-tolerant methods about data encode and decode, package identification (ID) field fault-tolerant methods, and cyclic redundancy checks fault-tolerant methods are discussed. The paper also presents some hardware implement methods about fault-tolerant design of data decode and test methods about fault-tolerant design of USB2.0 IP core system. These methods can offer the reference for development of USB2.0 system in all kinds of electronics instrumentations.

  2. Decentralized Fault Tolerant Control for a Class of Interconnected Nonlinear Systems. (United States)

    Shao, Shuai; Yang, Hao; Jiang, Bin; Cheng, Shuyao


    This paper proposes a decentralized fault tolerant methodology for a class of interconnected nonlinear systems. The key novelty of our proposed method is that fault tolerant control can be achieved without necessarily exchanging the state information between the subsystems and the couplings' effect can be dealt with utilizing the cyclic-small-gain methodology. Simulation results demonstrate effectively the validity of our proposed approach.

  3. Mapping of Fault-Tolerant Applications with Transparency on Distributed Embedded Systems

    DEFF Research Database (Denmark)

    Izosimov, Viacheslav; Pop, Paul; Eles, Petru


    In this paper we present an approach for the mapping optimization of fault-tolerant embedded systems for safety-critical applications. Processes and messages are statically scheduled. Process re-execution is used for recovering from multiple transient faults. We call process recovery transparent...

  4. Surveillance system and method having an operating mode partitioned fault classification model (United States)

    Bickford, Randall L. (Inventor)


    A system and method which partitions a parameter estimation model, a fault detection model, and a fault classification model for a process surveillance scheme into two or more coordinated submodels together providing improved diagnostic decision making for at least one determined operating mode of an asset.

  5. Implementation of a Wind Farm Turbine Control System with Short-Term Grid Faults Management

    DEFF Research Database (Denmark)

    Marra, Francesco; Rasmussen, Tonny Wederberg; Garcia-Valle, Rodrigo


    with the implementation of a control strategy in order to stay connected under grid faults. The method aimed to ensure that a wind farm turbine remains connected and no electric power is delivered to the grid during the fault period. The overall system was modelled and simulated by using the software Matlab/Simulink....

  6. Active Fault Diagnosis for Hybrid Systems Based on Sensitivity Analysis and EKF

    DEFF Research Database (Denmark)

    Gholami, Mehdi; Schiøler, Henrik; Bak, Thomas


    An active fault diagnosis approach for different kinds of faults is proposed. The input of the approach is designed off-line based on sensitivity analysis such that the maximum sensitivity for each individual system parameter is obtained. Using maximum sensitivity, results in a better precision i...

  7. Synthesis of Fault-Tolerant Embedded Systems with Checkpointing and Replication

    DEFF Research Database (Denmark)

    Izosimov, Viacheslav; Pop, Paul; Eles, Petru;


    We present an approach to the synthesis of fault-tolerant hard real-time systems for safety-critical applications. We use checkpointing with rollback recovery and active replication for tolerating transient faults. Processes are statically scheduled and communications are performed using the time...

  8. Energy-Aware Synthesis of Fault-Tolerant Schedules for Real-Time Distributed Embedded Systems

    DEFF Research Database (Denmark)

    Poulsen, Kåre Harbo; Pop, Paul; Izosimov, Viacheslav


    This paper presents a design optimisation tool for distributed embedded real-time systems that 1) decides mapping, fault-tolerance policy and generates a fault-tolerant schedule, 2) is targeted for hard real-time, 3) has hard reliability goal, 4) generates static schedule for processes and messages...

  9. Adaptive sensor-fault tolerant control for a class of multivariable uncertain nonlinear systems. (United States)

    Khebbache, Hicham; Tadjine, Mohamed; Labiod, Salim; Boulkroune, Abdesselem


    This paper deals with the active fault tolerant control (AFTC) problem for a class of multiple-input multiple-output (MIMO) uncertain nonlinear systems subject to sensor faults and external disturbances. The proposed AFTC method can tolerate three additive (bias, drift and loss of accuracy) and one multiplicative (loss of effectiveness) sensor faults. By employing backstepping technique, a novel adaptive backstepping-based AFTC scheme is developed using the fact that sensor faults and system uncertainties (including external disturbances and unexpected nonlinear functions caused by sensor faults) can be on-line estimated and compensated via robust adaptive schemes. The stability analysis of the closed-loop system is rigorously proven using a Lyapunov approach. The effectiveness of the proposed controller is illustrated by two simulation examples.

  10. Study of Fault Diagnosis Method for Wind Turbine with Decision Classification Algorithms and Expert System

    Directory of Open Access Journals (Sweden)

    Feng Yongxin


    Full Text Available Study on the fault diagnosis method through the combination of decision classification algorithms and expert system. The method of extracting diagnosis rules with the CTree software was given, and a fault diagnosis system based on CLIPS was developed. In order to verify the feasibility of the method, at first the sample data was got through the simulations under fault of direct-drive wind turbine and gearbox, then the diagnosis rules was extracted with the CTree software, at last the fault diagnosis system proposed and the rules was used to extracted to diagnose the fault simulated. Test results showed that the misdiagnosis rate both within 5%, thus the feasibility of the method was verified.

  11. Fault Diagnosis for Electrical Distribution Systems using Structural Analysis

    DEFF Research Database (Denmark)

    Knüppel, Thyge; Blanke, Mogens; Østergaard, Jacob


    Fault-tolerance in electrical distribution relies on the ability to diagnose possible faults and determine which components or units cause a problem or are close to doing so. Faults include defects in instrumentation, power generation, transformation and transmission. The focus of this paper...... redundancies in large sets of equations only from the structure (topology) of the equations. A salient feature is automated generation of redundancy relations. The method is indeed feasible in electrical networks where circuit theory and network topology together formulate the constraints that define...

  12. Application of Joint Parameter Identification and State Estimation to a Fault-Tolerant Robot System

    DEFF Research Database (Denmark)

    Sun, Zhen; Yang, Zhenyu


    The joint parameter identification and state estimation technique is applied to develop a fault-tolerant space robot system. The potential faults in the considered system are abrupt parametric faults, which indicate that some system parameters will immediately deviate from their nominal values...... if a fault happens. The concerned system parameters consist of deterministic parts as well as those describing the stochastic features in the system. Due to the purpose for design of reconfigurable control, these deviated system parameters need to be identified as precisely and quickly as possible. Meanwhile......, it would further simplify the reconfigurable design task and possibly speed up the system recovery, if the system state information under the new operating circumstance can be available along with faulty parameter information. The joint parameter identification and state estimation using the combined...

  13. Actuator fault diagnosis of time-delay systems based on adaptive observer

    Institute of Scientific and Technical Information of China (English)


    A novel approach for the actuator fault diagnosis of time-delay systems is presented by using an adaptive observer technique. Systems without model uncertainty are initially considered, followed by a discussion of a general situation where the system is subjected to either model uncertainty or external disturbance. An adaptive diagnostic algorithm is developed to diagnose the fault, and a modified version is proposed for general system to improve robustness. The selection of the threshold for fault detection is also discussed. Finally, a numerical example is given to illustrate the efficiency of the proposed method.

  14. Four-dimensional transform fault processes: progressive evolution of step-overs and bends (United States)

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


    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

  15. Development Ground Fault Detecting System for D.C Voltage Line

    Energy Technology Data Exchange (ETDEWEB)

    Kim Taek Soo; Song Ung Il; Gwon, Young Dong; Lee Hyoung Kee [Korea Electric Power Research Institute, Taejon (Korea, Republic of)


    It is necessary to keep the security of reliability and to maximize the efficiency of maintenance by prompt detection of a D.C feeder ground fault point at the built ed or a building power plants. At present, the most of the power plants are set up the ground fault indicator lamp in the monitor room. If a ground fault occurs on DC voltage feeder, a current through the ground fault relay is adjusted and the lamps have brightened while the current flows the relay coil. In order to develop such a system, it is analyzed a D.C feeder ground circuit theoretically and studied a principles which can determine ground fault point or a polarity discrimination and a phase discrimination of the line. So, the developed system through this principles can compute a resistance ground fault current and a capacitive ground fault current. It shows that the system can defect a ground fault point or a bad insulated line by measuring a power plant D.C feeder insulation resistance at the un interruptible power status, and therefore the power plant could protect an unexpected service interruption . (author). 18 refs., figs.

  16. Study on Unified Chaotic System-Based Wind Turbine Blade Fault Diagnostic System (United States)

    Kuo, Ying-Che; Hsieh, Chin-Tsung; Yau, Her-Terng; Li, Yu-Chung

    At present, vibration signals are processed and analyzed mostly in the frequency domain. The spectrum clearly shows the signal structure and the specific characteristic frequency band is analyzed, but the number of calculations required is huge, resulting in delays. Therefore, this study uses the characteristics of a nonlinear system to load the complete vibration signal to the unified chaotic system, applying the dynamic error to analyze the wind turbine vibration signal, and adopting extenics theory for artificial intelligent fault diagnosis of the analysis signal. Hence, a fault diagnostor has been developed for wind turbine rotating blades. This study simulates three wind turbine blade states, namely stress rupture, screw loosening and blade loss, and validates the methods. The experimental results prove that the unified chaotic system used in this paper has a significant effect on vibration signal analysis. Thus, the operating conditions of wind turbines can be quickly known from this fault diagnostic system, and the maintenance schedule can be arranged before the faults worsen, making the management and implementation of wind turbines smoother, so as to reduce many unnecessary costs.

  17. Chaotic Extension Neural Network-Based Fault Diagnosis Method for Solar Photovoltaic Systems

    Directory of Open Access Journals (Sweden)

    Kuo-Nan Yu


    Full Text Available At present, the solar photovoltaic system is extensively used. However, once a fault occurs, it is inspected manually, which is not economical. In order to remedy the defect of unavailable fault diagnosis at any irradiance and temperature in the literature with chaos synchronization based intelligent fault diagnosis for photovoltaic systems proposed by Hsieh et al., this study proposed a chaotic extension fault diagnosis method combined with error back propagation neural network to overcome this problem. It used the nn toolbox of matlab 2010 for simulation and comparison, measured current irradiance and temperature, and used the maximum power point tracking (MPPT for chaotic extraction of eigenvalue. The range of extension field was determined by neural network. Finally, the voltage eigenvalue obtained from current temperature and irradiance was used for the fault diagnosis. Comparing the diagnostic rates with the results by Hsieh et al., this scheme can obtain better diagnostic rates when the irradiances or the temperatures are changed.

  18. Design of parametric fault detection systems:An H-infinity optimization approach

    Institute of Scientific and Technical Information of China (English)

    Maiying ZHONG; Chuanfeng MA; Steven X.DING


    Problems related to the design of observer-based parametric fault detection (PFD) systems are studied.The core of our study is to first describe the faults occurring in system actuators,sensors and components in the form of additive parameter deviations,then to transform the PFD problems into a similar additive fault setup,based on which an optimal observer-based optimization fault detection approach is proposed.A constructive solution optimal in the sense of minimizing a certain performance index is developed.The main results consist of defining parametric fault detectability,formulating a PFD optimization problem and its solution.A numerical example to demonstrate the effectiveness of the proposed approach is provided.

  19. Application of a Fault Detection and Isolation System on a Rotary Machine

    Directory of Open Access Journals (Sweden)

    Silvia M. Zanoli


    Full Text Available The paper illustrates the design and the implementation of a Fault Detection and Isolation (FDI system to a rotary machine like a multishaft centrifugal compressor. A model-free approach, that is, the Principal Component Analysis (PCA, has been employed to solve the fault detection issue. For the fault isolation purpose structured residuals have been adopted while an adaptive threshold has been designed in order to detect and to isolate the faults. To prove the goodness of the proposed FDI system, historical data of a nitrogen centrifugal compressor employed in a refinery plant are considered. Tests results show that detection and isolation of single as well as multiple faults are successfully achieved.

  20. Model-Based Fault Tolerant Control for Hybrid Dynamic Systems with Sensor Faults%一类带有传染器故障的混合系统的容错控制

    Institute of Scientific and Technical Information of China (English)

    杨浩; 冒泽慧; 姜斌


    A model-based fault tolerant control approach for hybrid linear dynamic systems is proposed in this paper. The proposed method, taking advantage of reliable control, can maintain the performance of the faulty system during the time delay of fault detection and diagnosis (FDD) and fault accommodation (FA), which can be regarded as the first line of defence against sensor faults.Simulation results of a three-tank system with sensor fault are given to show the efficiency of the method.

  1. Coulomb static stress interactions between simulated M>7 earthquakes and major faults in Southern California (United States)

    Rollins, J. C.; Ely, G. P.; Jordan, T. H.


    We calculate the Coulomb stress changes imparted to major Southern California faults by thirteen simulated worst-case-scenario earthquakes for the region, including the “Big Ten” scenarios (Ely et al, in progress). The source models for the earthquakes are variable-slip simulations from the SCEC CyberShake project (Graves et al, 2010). We find strong stress interactions between the San Andreas and subparallel right-lateral faults, thrust faults under the Los Angeles basin, and the left-lateral Garlock Fault. M>7 earthquakes rupturing sections of the southern San Andreas generally decrease Coulomb stress on the San Jacinto and Elsinore faults and impart localized stress increases and decreases to the Garlock, San Cayetano, Puente Hills and Sierra Madre faults. A M=7.55 quake rupturing the San Andreas between Lake Hughes and San Gorgonio Pass increases Coulomb stress on the eastern San Cayetano fault, consistent with Deng and Sykes (1996). M>7 earthquakes rupturing the San Jacinto, Elsinore, Newport-Inglewood and Palos Verdes faults decrease stress on parallel right-lateral faults. A M=7.35 quake on the San Cayetano Fault decreases stress on the Garlock and imparts localized stress increases and decreases to the San Andreas. A M=7.15 quake on the Puente Hills Fault increases stress on the San Andreas and San Jacinto faults, decreases stress on the Sierra Madre Fault and imparts localized stress increases and decreases to the Newport-Inglewood and Palos Verdes faults. A M=7.25 shock on the Sierra Madre Fault increases stress on the San Andreas and decreases stress on the Puente Hills Fault. These findings may be useful for hazard assessment, paleoseismology, and comparison with dynamic stress interactions featuring the same set of earthquakes.

  2. Research on Key Techniques of Condition Monitoring and Fault Diagnosing Systems of Machine Groups

    Institute of Scientific and Technical Information of China (English)

    WANG Yan-kai; LIAO Ming-fu; WANG Si-ji


    This paper describes the development of the condition monitoring and fault diagnosing system of a group of rotating machinery. The data management is performed by means of double redundant data bases stored simultaneously in both the analyzing server and monitoring client. In this way, high reliability of the storage of data is guaranteed. Condensation of trend data releases much space resource of the hard disk. Diagnosing strategies orientated to different typical faults of rotating machinery are developed and incorporated into the system. Experimental verification shows that the system is suitable and effective for condition monitoring and fault diagnosing for a rotating machine group.

  3. A Piecewise Affine Hybrid Systems Approach to Fault Tolerant Satellite Formation Control

    DEFF Research Database (Denmark)

    Grunnet, Jacob Deleuran; Larsen, Jesper Abildgaard; Bak, Thomas


    In this paper a procedure for modelling satellite formations   including failure dynamics as a piecewise-affine hybrid system is   shown. The formulation enables recently developed methods and tools   for control and analysis of piecewise-affine systems to be applied   leading to synthesis of fault...... tolerant controllers and analysis of   the system behaviour given possible faults.  The method is   illustrated using a simple example involving two satellites trying   to reach a specific formation despite of actuator faults occurring....


    Directory of Open Access Journals (Sweden)

    Yu. O. Kuzmin


    Full Text Available Recent deformation processes taking place in real time are analyzed on the basis of data on fault zones which were collected by long-term detailed geodetic survey studies with application of field methods and satellite monitoring.A new category of recent crustal movements is described and termed as parametrically induced tectonic strain in fault zones. It is shown that in the fault zones located in seismically active and aseismic regions, super intensive displacements of the crust (5 to 7 cm per year, i.e. (5 to 7·10–5 per year occur due to very small external impacts of natural or technogenic / industrial origin.The spatial discreteness of anomalous deformation processes is established along the strike of the regional Rechitsky fault in the Pripyat basin. It is concluded that recent anomalous activity of the fault zones needs to be taken into account in defining regional regularities of geodynamic processes on the basis of real-time measurements.The paper presents results of analyses of data collected by long-term (20 to 50 years geodetic surveys in highly seismically active regions of Kopetdag, Kamchatka and California. It is evidenced by instrumental geodetic measurements of recent vertical and horizontal displacements in fault zones that deformations are ‘paradoxically’ deviating from the inherited movements of the past geological periods.In terms of the recent geodynamics, the ‘paradoxes’ of high and low strain velocities are related to a reliable empirical fact of the presence of extremely high local velocities of deformations in the fault zones (about 10–5 per year and above, which take place at the background of slow regional deformations which velocities are lower by the order of 2 to 3. Very low average annual velocities of horizontal deformation are recorded in the seismic regions of Kopetdag and Kamchatka and in the San Andreas fault zone; they amount to only 3 to 5 amplitudes of the earth tidal deformations per year.A ‘fault

  5. Designing Fault-Injection Experiments for the Reliability of Embedded Systems (United States)

    White, Allan L.


    This paper considers the long-standing problem of conducting fault-injections experiments to establish the ultra-reliability of embedded systems. There have been extensive efforts in fault injection, and this paper offers a partial summary of the efforts, but these previous efforts have focused on realism and efficiency. Fault injections have been used to examine diagnostics and to test algorithms, but the literature does not contain any framework that says how to conduct fault-injection experiments to establish ultra-reliability. A solution to this problem integrates field-data, arguments-from-design, and fault-injection into a seamless whole. The solution in this paper is to derive a model reduction theorem for a class of semi-Markov models suitable for describing ultra-reliable embedded systems. The derivation shows that a tight upper bound on the probability of system failure can be obtained using only the means of system-recovery times, thus reducing the experimental effort to estimating a reasonable number of easily-observed parameters. The paper includes an example of a system subject to both permanent and transient faults. There is a discussion of integrating fault-injection with field-data and arguments-from-design.

  6. Real-time fault detection method based on belief rule base for aircraft navigation system

    Institute of Scientific and Technical Information of China (English)

    Zhao Xin; Wang Shicheng; Zhang Jinsheng; Fan Zhiliang; Min Haibo


    Real-time and accurate fault detection is essential to enhance the aircraft navigation system's reliability and safety.The existent detection methods based on analytical model draws back at simultaneously detecting gradual and sudden faults.On account of this reason,we propose an online detection solution based on non-analytical model.In this article,the navigation system fault detection model is established based on belief rule base (BRB),where the system measuring residual and its changing rate are used as the inputs of BRB model and the fault detection function as the output.To overcome the drawbacks of current parameter optimization algorithms for BRB and achieve online update,a parameter recursive estimation algorithm is presented for online BRB detection model based on expectation maximization (EM) algorithm.Furthermore,the proposed method is verified by navigation experiment.Experimental results show that the proposed method is able to effectively realize online parameter evaluation in navigation system fault detection model.The output of the detection model can track the fault state very well,and the faults can be diagnosed in real time and accurately.In addition,the detection ability,especially in the probability of false detection,is superior to offline optimization method,and thus the system reliability has great improvement.

  7. Fault Identification Algorithm Based on Zone-Division Wide Area Protection System

    Directory of Open Access Journals (Sweden)

    Xiaojun Liu


    Full Text Available As the power grid becomes more magnified and complicated, wide-area protection system in the practical engineering application is more and more restricted by the communication level. Based on the concept of limitedness of wide-area protection system, the grid with complex structure is divided orderly in this paper, and fault identification and protection action are executed in each divided zone to reduce the pressure of the communication system. In protection zone, a new wide-area protection algorithm based on positive sequence fault components directional comparison principle is proposed. The special associated intelligent electronic devices (IEDs zones which contain buses and transmission lines are created according to the installation location of the IEDs. When a fault occurs, with the help of the fault information collecting and sharing from associated zones with the fault discrimination principle defined in this paper, the IEDs can identify the fault location and remove the fault according to the predetermined action strategy. The algorithm will not be impacted by the load changes and transition resistance and also has good adaptability in open phase running power system. It can be used as a main protection, and it also can be taken into account for the back-up protection function. The results of cases study show that, the division method of the wide-area protection system and the proposed algorithm are effective.

  8. Multi-Agent System Fault Protection with Topology Identification in Microgrids

    Directory of Open Access Journals (Sweden)

    Stephanus Antonius Ananda


    Full Text Available Data acquisition and supervisory control are usually performed using client-server architecture and centralized control in conventional power systems. However, the message transmission and fault clearing are too slow for large-scale complex power systems. Microgrid systems have various types of distributed energy resources (DERs which are quite different in characteristics and capacities, thus, the client-server architecture and centralized control are inadequate to control and operate in microgrids. Based on MATLAB/Simulink (ver.R2012a simulation software and Java Agent Development Framework (JADE (JADE 4.1.1-revision 6532, this paper proposes a novel fault protection technology that used multi-agent system (MAS to perform fault detection, fault isolation and service restoration in microgrids. A new topology identification method using the YBus Matrix Algorithm is presented to successfully recognize the network configurations. The identification technology can respond to microgrid variations. Furthermore, the interactive communications among intelligent electronic devices (IEDs, circuit breakers (CBs, and agents are clarified during fault occurrence. The simulation results show that the proposed MAS-based microgrids can promptly isolate faults and protect the system against faults in real time.

  9. Steady Fault Cha