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Sample records for cathedral rapids fault

  1. Paleoseismic study of the Cathedral Rapids fault in the northern Alaska Range near Tok, Alaska

    NASA Astrophysics Data System (ADS)

    Koehler, R. D.; Farrell, R.; Carver, G. A.

    2010-12-01

    The Cathedral Rapids fault extends ~40 km between the Tok and Robertson River valleys and is the easternmost fault in a series of active south-dipping imbricate thrust faults which bound the northern flank of the Alaska Range. Collectively, these faults accommodate a component of convergence transferred north of the Denali fault and related to the westward (counterclockwise) rotation of the Wrangell Block driven by relative Pacific/North American plate motion along the eastern Aleutian subduction zone and Fairweather fault system. To the west, the system has been defined as the Northern Foothills Fold and Thrust Belt (NFFTB), a 50-km-wide zone of east-west trending thrust faults that displace Quaternary deposits and have accommodated ~3 mm/yr of shortening since latest Pliocene time (Bemis, 2004). Over the last several years, the eastward extension of the NFFTB between Delta Junction and the Canadian border has been studied by the Alaska Division of Geological & Geophysical Surveys to better characterize faults that may affect engineering design of the proposed Alaska-Canada natural gas pipeline and other infrastructure. We summarize herein reconnaissance field observations along the western part of the Cathedral Rapids fault. The western part of the Cathedral Rapids fault extends 21 km from Sheep Creek to Moon Lake and is characterized by three roughly parallel sinuous traces that offset glacial deposits of the Illinoian to early Wisconsinan Delta glaciations and the late Wisconsinan Donnelly glaciation, as well as, Holocene alluvial deposits. The northern trace of the fault is characterized by an oversteepened, beveled, ~2.5-m-high scarp that obliquely cuts a Holocene alluvial fan and projects into the rangefront. Previous paleoseismic studies along the eastern part of the Cathedral Rapids fault and Dot “T” Johnson fault indicate multiple latest Pleistocene and Holocene earthquakes associated with anticlinal folding and thrust faulting (Carver et al., 2010). Combined with this previous work, our paleoseismic assessment of the western Cathedral Rapids fault, including trenching in fall 2010, may contribute to increasing the understanding of the style and timing of deformation for faults bounding the northern flank of the Alaska Range. These data may also provide insight into the eastern extent of the NFFTB and its role in accommodating regional shortening.

  2. Denali Fault: Black Rapids Glacier

    View eastward along Black Rapids Glacier. The Denali fault follows the trace of the glacier. These very large rockslides went a mile across the glacier on the right side. Investigations of the headwall of the middle landslide indicate a volume at least as large as that which fell, has dropped a mete...

  3. Cathedral Spires in Fog

    In this image, Cathedral Spires can be seen shrouded in fog from Tunnel View in Yosemite National Park. From left to right, the peaks are known as Lower Cathedral Rock, Middle Cathedral Rock, and Higher Cathedral Rock. They are composed of granite and are part of the Sierra Nevada batholith. Like th...

  4. The Cathedral as Text.

    ERIC Educational Resources Information Center

    Calkins, Robert G.

    1995-01-01

    Characterizes the medieval cathedral as an architectural encyclopedia, expressing the humanistic concerns, beliefs, and aspirations of the period in which it was built. Explains the theological, political, and social significance of the cathedral's architectural characteristics from the floor plan to the spires. Discusses the process and problems…

  5. Earthquake Resistant Cathedral in Chile

    A cathedral in the central square of Chillán, Chile replaces the ancient cathedral that collapsed during the strong earthquake of 1939. This modern structure was constructed with earthquake resistance as the primary consideration. The only damage caused by the M 8.8 earthquake on Feb. 27, 2010 was b...

  6. An earthquake mechanism based on rapid sealing of faults

    USGS Publications Warehouse

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

    1992-01-01

    RECENT seismological, heat flow and stress measurements in active fault zones such as the San Andreas have led to the suggestion1,2 that such zones can be relatively weak. One explanation for this may be the presence of overpressured fluids along the fault3-5, which would reduce the shear stress required for sliding by partially 'floating' the rock. Although several mechanisms have been proposed for overpressurizing fault fluids3,4,6,7, we recall that 'pressure seals' are known to form in both sedimentary8 and igneous9 rocks by the redistribution of materials in solution; the formation of such a seal along the boundaries of a fault will prevent the communication of fluids between the porous, deforming fault zone and the surrounding country rock. Compaction of fault gouge, under hydrostatic loading and/or during shear, elevates pore pressure in the sealed fault and allows sliding at low shear stress. We report the results of laboratory sliding experiments on granite, which demonstrate that the sliding resistance of faults can be significantly decreased by sealing and compaction. The weakening that results from shear-induced compaction can be rapid, and may provide an instability mechanism for earthquakes.

  7. Half Dome from Cathedral Spires

    In this image, Half Dome may be seen from the base of Cathedral Spires. Half Dome is a granite dome, rising about 4,737 ft (1,444 m) above the surrounding valley. It is part of the Sierra Nevada batholith and is one of Yosemite National Park's most famous features....

  8. An Exploratory Study of Cathedral Music Libraries.

    ERIC Educational Resources Information Center

    McGuire, Mark J.

    A survey was mailed to the 185 U.S. Roman Catholic cathedrals to determine the nature and extent of cathedral music libraries. In addition to baseline demographic information, survey questions focused on the following topics: (1) music library staffing and management; (2) methods of cataloging and classification; (3) the use and creation of…

  9. Cathedral house & crocker fence, Taylor Street east and north ...

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

    Cathedral house & crocker fence, Taylor Street east and north elevations, perspective view from the northeast - Grace Cathedral, George William Gibbs Memorial Hall, 1051 Taylor Street, San Francisco, San Francisco County, CA

  10. Fault structures in rapidly quenched Ni-Mo binary alloys

    NASA Technical Reports Server (NTRS)

    Jayaraman, N.; Tewari, S. N.

    1986-01-01

    Fault structures in two Ni-Mo alloy ribbons (Ni-28 at. pct Mo and Ni-35 at. pct Mo) cast by a free jet chill block melt spinning process were studied. Thin foils for TEM studies were made by electrochemical thinning using an alcohol/butyl cellosolve/perchloric acid mixture in a twin jet electropolishing device. The samples displayed typical grains containing linear faulted regions on the wheelside of the two alloy ribbons. However, an anomalous diffraction behavior was observed upon continuous tilting of the sample: the network of diffraction spots from a single grain appeared to expand or contract and rotate. This anomalous diffraction behavior was explained by assuming extended spike formation at reciprocal lattice points, resulting in a network of continuous rel rods. The validity of the model was confirmed by observations of a cross section of the reciprocal lattice parallel to the rel rods.

  11. Rapid Assessment of Earthquakes with Radar and Optical Geodetic Imaging and Finite Fault Models (Invited)

    NASA Astrophysics Data System (ADS)

    Fielding, E. J.; Sladen, A.; Simons, M.; Rosen, P. A.; Yun, S.; Li, Z.; Avouac, J.; Leprince, S.

    2010-12-01

    Earthquake responders need to know where the earthquake has caused damage and what is the likely intensity of damage. The earliest information comes from global and regional seismic networks, which provide the magnitude and locations of the main earthquake hypocenter and moment tensor centroid and also the locations of aftershocks. Location accuracy depends on the availability of seismic data close to the earthquake source. Finite fault models of the earthquake slip can be derived from analysis of seismic waveforms alone, but the results can have large errors in the location of the fault ruptures and spatial distribution of slip, which are critical for estimating the distribution of shaking and damage. Geodetic measurements of ground displacements with GPS, LiDAR, or radar and optical imagery provide key spatial constraints on the location of the fault ruptures and distribution of slip. Here we describe the analysis of interferometric synthetic aperture radar (InSAR) and sub-pixel correlation (or pixel offset tracking) of radar and optical imagery to measure ground coseismic displacements for recent large earthquakes, and lessons learned for rapid assessment of future events. These geodetic imaging techniques have been applied to the 2010 Leogane, Haiti; 2010 Maule, Chile; 2010 Baja California, Mexico; 2008 Wenchuan, China; 2007 Tocopilla, Chile; 2007 Pisco, Peru; 2005 Kashmir; and 2003 Bam, Iran earthquakes, using data from ESA Envisat ASAR, JAXA ALOS PALSAR, NASA Terra ASTER and CNES SPOT5 satellite instruments and the NASA/JPL UAVSAR airborne system. For these events, the geodetic data provided unique information on the location of the fault or faults that ruptured and the distribution of slip that was not available from the seismic data and allowed the creation of accurate finite fault source models. In many of these cases, the fault ruptures were on previously unknown faults or faults not believed to be at high risk of earthquakes, so the area and degree of damage was a surprise. The satellite or airborne imagery was not available in the first days after these earthquakes, and hand-crafted analysis added more time after data delivery, so source assessment products were not useful for the initial rescue operations, but they were useful for guiding field mapping and early recovery planning. Future rapid assessment of earthquakes could be speeded by automated analysis and more prompt data accessibility to provide products in time to benefit rescue operations.

  12. DISTANT VIEW OF ST. FRANCIS DE SALES CATHEDRAL, LOOKING NORTH ...

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

    DISTANT VIEW OF ST. FRANCIS DE SALES CATHEDRAL, LOOKING NORTH ALONG MARTIN LUTHER KING JR. WAY FROM 14TH STREET - St. Francis de Sales Church, 2100 Martin Luther King, Jr. Way, Oakland, Alameda County, CA

  13. Rapid and simultaneous estimation of fault slip and heterogeneous lithospheric viscosity from post-seismic deformation

    NASA Astrophysics Data System (ADS)

    Hines, T. T.; Hetland, E. A.

    2016-01-01

    Post-seismic deformation is commonly attributed to viscoelastic relaxation and/or afterslip, although discerning between the two driving mechanisms can be difficult. A major complication in modeling post-seismic deformation is that forward models can be computationally expensive, making it difficult to adequately search model space to find the optimal fault slip distribution and lithospheric viscosity structure that can explain observable post-seismic deformation. We propose an inverse method which uses coseismic and early post-seismic deformation to rapidly and simultaneously estimate a fault slip history and an arbitrarily discretized viscosity structure of the lithosphere. Our method is based on an approximation which is applicable to the early post-seismic period and expresses surface deformation resulting from viscoelastic relaxation as a linearized function with respect to lithospheric fluidity. We demonstrate this approximation using two-dimensional earthquake models. We validate the approximation and our inverse method using two three-dimensional synthetic tests. The success of our synthetic tests suggests that our method is capable of distinguishing the mechanisms driving early post-seismic deformation and recovering an effective viscosity structure of the lithosphere.

  14. Similar Fracture Patterns in Human Nose and Gothic Cathedral.

    PubMed

    Lee, Shu Jin; Tse, Kwong Ming; Lee, Heow Pueh

    2015-10-01

    This study proposes that the bony anatomy of the human nose and masonry structure of the Gothic cathedral are geometrically similar, and have common fracture patterns. We also aim to correlate the fracture patterns observed in patients' midface structures with those seen in the Gothic cathedral using computational approach. CT scans of 33 patients with facial fractures were examined and compared with computer simulations of both the Gothic cathedral and human nose. Three similar patterns were found: (1) Cracks of the nasal arch with crumpling of the vertical buttresses akin to the damage seen during minor earthquakes; (2) lateral deviation of the central nasal arch and collapse of the vertical buttresses akin to those due to lateral forces from wind and in major earthquakes; and (3) Central arch collapse seen as a result of collapse under excessive dead weight. Interestingly, the finding of occult nasal and septal fractures in the mandible fractures with absence of direct nasal trauma highlights the possibility of transmission of forces from the foundation to the arch leading to structural failure. It was also found that the structural buttresses of the Gothic cathedral delineate the vertical buttresses in the human midface structure. These morphologic similarities between the human nose and Gothic cathedral will serve as a basis to study the biomechanics of nasal fractures. Identification of structural buttresses in a skeletal structure has important implications for reconstruction as reestablishment of structural continuity restores normal anatomy and architectural stability of the human midface structure. PMID:26579871

  15. Rapid kinematic finite-fault inversion for an Mw 7+ scenario earthquake in the Marmara Sea: an uncertainty study

    NASA Astrophysics Data System (ADS)

    Diao, Faqi; Wang, Rongjiang; Aochi, Hideo; Walter, Thomas R.; Zhang, Yong; Zheng, Yong; Xiong, Xiong

    2016-02-01

    During the 20th century, a series of devastating earthquakes occurred along the North Anatolian Fault. These generally propagated westwards, such that the main fault segment beneath the Marmara Sea appears as a seismic gap. For the nearby megacity Istanbul, rapid seismic hazard assessment is currently of great importance. A key issue is how a strong earthquake in the Marmara Sea can be characterized reliably and rapidly using the seismic network currently operating in this region. In order to investigate this issue, several scenario earthquakes on the main Marmara fault are simulated through dynamic modelling based on a 3-D structure model. The synthetic datasets are then used to reconstruct the source processes of the causal events with a recently developed iterative deconvolution and stacking method based on simplified 1-D Earth structure models. The results indicate that, by using certain a priori information about the fault geometry and focal mechanism, the tempo-spatial slip patterns of the input scenarios can be well resolved. If reasonable uncertainties are considered for the a priori information, the key source parameters, such as moment magnitude, fault size and slip centroid, can still be estimated reliably, while the detailed tempo-spatial rupture pattern may reveal significant variations. To reduce the effect induced by employing the inaccurate event location and focal mechanism, a new approach for absolute source imaging is proposed and tested. We also investigate the performance of the new source imaging tool for near real-time source inversion under the current network configuration in the Marmara Sea region. The results obtained are meaningful particularly for developing the rapid earthquake response system for the megacity Istanbul.

  16. A rapid estimation of tsunami run-up based on finite fault models

    NASA Astrophysics Data System (ADS)

    Campos, J.; Fuentes, M. A.; Hayes, G. P.; Barrientos, S. E.; Riquelme, S.

    2014-12-01

    Many efforts have been made to estimate the maximum run-up height of tsunamis associated with large earthquakes. This is a difficult task, because of the time it takes to construct a tsunami model using real time data from the source. It is possible to construct a database of potential seismic sources and their corresponding tsunami a priori. However, such models are generally based on uniform slip distributions and thus oversimplify our knowledge of the earthquake source. Instead, we can use finite fault models of earthquakes to give a more accurate prediction of the tsunami run-up. Here we show how to accurately predict tsunami run-up from any seismic source model using an analytic solution found by Fuentes et al, 2013 that was especially calculated for zones with a very well defined strike, i.e, Chile, Japan, Alaska, etc. The main idea of this work is to produce a tool for emergency response, trading off accuracy for quickness. Our solutions for three large earthquakes are promising. Here we compute models of the run-up for the 2010 Mw 8.8 Maule Earthquake, the 2011 Mw 9.0 Tohoku Earthquake, and the recent 2014 Mw 8.2 Iquique Earthquake. Our maximum rup-up predictions are consistent with measurements made inland after each event, with a peak of 15 to 20 m for Maule, 40 m for Tohoku, and 2,1 m for the Iquique earthquake. Considering recent advances made in the analysis of real time GPS data and the ability to rapidly resolve the finiteness of a large earthquake close to existing GPS networks, it will be possible in the near future to perform these calculations within the first five minutes after the occurrence of any such event. Such calculations will thus provide more accurate run-up information than is otherwise available from existing uniform-slip seismic source databases.

  17. A teleseismic study of the 2002 Denali fault, Alaska, earthquake and implications for rapid strong-motion estimation

    USGS Publications Warehouse

    Ji, C.; Helmberger, D.V.; Wald, D.J.

    2004-01-01

    Slip histories for the 2002 M7.9 Denali fault, Alaska, earthquake are derived rapidly from global teleseismic waveform data. In phases, three models improve matching waveform data and recovery of rupture details. In the first model (Phase I), analogous to an automated solution, a simple fault plane is fixed based on the preliminary Harvard Centroid Moment Tensor mechanism and the epicenter provided by the Preliminary Determination of Epicenters. This model is then updated (Phase II) by implementing a more realistic fault geometry inferred from Digital Elevation Model topography and further (Phase III) by using the calibrated P-wave and SH-wave arrival times derived from modeling of the nearby 2002 M6.7 Nenana Mountain earthquake. These models are used to predict the peak ground velocity and the shaking intensity field in the fault vicinity. The procedure to estimate local strong motion could be automated and used for global real-time earthquake shaking and damage assessment. ?? 2004, Earthquake Engineering Research Institute.

  18. Finite-fault source inversion using teleseismic P waves: Simple parameterization and rapid analysis

    USGS Publications Warehouse

    Mendoza, C.; Hartzell, S.

    2013-01-01

    We examine the ability of teleseismic P waves to provide a timely image of the rupture history for large earthquakes using a simple, 2D finite‐fault source parameterization. We analyze the broadband displacement waveforms recorded for the 2010 Mw∼7 Darfield (New Zealand) and El Mayor‐Cucapah (Baja California) earthquakes using a single planar fault with a fixed rake. Both of these earthquakes were observed to have complicated fault geometries following detailed source studies conducted by other investigators using various data types. Our kinematic, finite‐fault analysis of the events yields rupture models that similarly identify the principal areas of large coseismic slip along the fault. The results also indicate that the amount of stabilization required to spatially smooth the slip across the fault and minimize the seismic moment is related to the amplitudes of the observed P waveforms and can be estimated from the absolute values of the elements of the coefficient matrix. This empirical relationship persists for earthquakes of different magnitudes and is consistent with the stabilization constraint obtained from the L‐curve in Tikhonov regularization. We use the relation to estimate the smoothing parameters for the 2011 Mw 7.1 East Turkey, 2012 Mw 8.6 Northern Sumatra, and 2011 Mw 9.0 Tohoku, Japan, earthquakes and invert the teleseismic P waves in a single step to recover timely, preliminary slip models that identify the principal source features observed in finite‐fault solutions obtained by the U.S. Geological Survey National Earthquake Information Center (USGS/NEIC) from the analysis of body‐ and surface‐wave data. These results indicate that smoothing constraints can be estimated a priori to derive a preliminary, first‐order image of the coseismic slip using teleseismic records.

  19. Materials Physics of Faults in Rapid Shear and Consequences for Earthquake Dynamics (Louis Néel Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Rice, J. R.

    2012-04-01

    Field observations of maturely slipped faults show that despite a generally broad zone of damage by cracking and granulation, large shear deformation, and therefore heat generation, in individual earthquakes takes place with extreme localization to a zone of order 1 mm or less width within a finely granulated fault core. Relevant fault weakening processes during large crustal events are therefore likely to be thermally influenced, although a constraint to be met, from scarcity of pseudotachylite, is that melting within fault zones seems relatively rare, at least in the up per crust. Further, given the porosit y of damage zones, it seems reasonable to assume in-situ water presence. The lecture reviews current understanding of the materials physics underlying rapid shear of such fault zones, addressing questions like: Why is there severe localization? What are the dynamic relations between shear stress sustained by the fault and its slip history? How do those relations, taken to provide the boundary conditions on a rupturing interface between elastic regions of the earth, control key features of the dynamics of earthquakes? Primary dynamic weakening mechanisms, expected active in at least the early phases of nearly all crustal events, are flash heating at highly stressed frictional micro-contacts and thermal pressurization of native fault-zone pore fluid, the latter with a net effect that depends on interactions with dilatancy. Other weakening processes may also become active at large enough T rise, still prior to bulk melting, including endothermic decomposition reactions releasing a CO2 or H2O fluid phase under conditions that the fluid and solid products would, at the same p and T , occupy more volume than the parent rock, so that the pore fluid is forced to undergo severe pressure increase. The endothermic nature of the reactions buffers against melting because frictional work is absorbed into enthalpy increase of the reactants. There may also be a contribution to the weakening linked to the typically nanoscale range of the solid product phases. The results, applied to modeling of spontaneous slip ruptures, show how faults can be statically strong yet dynamically weak, and operate under low overall driving stress, in a manner that generates negligible heat and meets major seismic constraints on slip, stress drop, and self-healing rupture mode. They also shed light on how fault segments that normally shear stably, so as to not nucleate earthquakes, can nevertheless take part in major events when a high-slip rupture impinges from a bordering segment. The studies reviewed have been done collaboratively with, or draw on the separate insights of, N. Brantut, M. Cocco, E. Dunham, D. Garagash, D. Goldsby, N. Lapusta, H. Noda, J. Platt, A. Rempel, J. Rudnicki, P. Segall, T. Shimamoto, J. Sulem, T. Tullis and I. Vardoulakis.

  20. The Sagrada Familia Cathedral where Gaudi envisaged his bell music

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Shigeru; Narita, Takafumi

    2001-05-01

    The Sagrada Familia Cathedral in Barcelona, Spain was constructed in 1882. According to Antoni Gaudi, who worked over its grand plan, the Cathedral was supposed to be a huge musical instrument as a whole in the event of completion. As as result, the music of bells was expected to echo through the air of Barcelona from the belfries. However, Gaudi's true intention cannot be exactly known because the materials prepared by him were destroyed by war fire. If his idea of the Sagrada Familia as an architechtural music instrument is true, an acoustical balance should be considered between the roles of the Cathedral: bell music from the belfries and quiet service in the chapel. Basic structure of the Sagrada Familia seems to be an ensemble of twin towers. Following such speculation, we made a simplified acrylic 1/25-scale model of the lower structure of a twin tower located at the left side of the Birth Gate. The higher structure of this twin tower corresponds to the pinnacle where the bells should be arranged. The lower structure (about 43 m in actual height) has five passages connecting two towers. One of two towers includes five or six tandem columns whose ends are both squeezed to about 1.5 m in diameter. These columns seem to function as a kind of muffler. The location and shape of the roof over the nave is indefinite and tentatively supposed at the top of the lower structure. Based on our scale model, acoustical characteristics of the lower twin-tower structure as a muffler and acoustical differences between the exterior field and nave field will be reported and discussed.

  1. "Friends" of Anglican Cathedrals: Norms and Values. Befriending, Friending or Misnomer?

    ERIC Educational Resources Information Center

    Muskett, Judith A.

    2013-01-01

    Loyal supporters of Anglican cathedrals first subscribed to "Friends" associations in the late 1920s. Yet, in 1937, a journalist in "The Times" portrayed cathedrals as a "queer thing to be a friend of." Drawing on theories of friendship from a range of disciplines, and surveys of what has been proclaimed in the public…

  2. Rapid fault model estimation based on RTK-GPS and its application to near-field tsunami forecasting

    NASA Astrophysics Data System (ADS)

    Kobayashi, T.; Ohta, Y.; Miura, S.; Tsushima, H.; Hino, R.; Takasu, T.; Fujimoto, H.

    2011-12-01

    The 2011 off the Pacific coast of Tohoku Earthquake (Mw 9.0) generated a huge tsunami that inflicted enormous damage on the Pacific side of Tohoku region. Three minutes after the earthquake, the Japan Meteorological Agency issued a tsunami warning based on the seismic data. The estimated maximum tsunami heights (up to 6 m), however, were clearly smaller than the observed one (more than 10 m) because of underestimation of the earthquake magnitude. The magnitude can be derived within a short period following the earthquake, which can saturate for such great earthquakes. This example clearly shows necessity of accurate tsunami early warning system and importance of the rapid determination of reliable earthquake sizes. Blewitt et al. [GRL, 2006] already pointed out that a true earthquake size and its tsunamigenic potential could be determined using GPS data. The permanent displacement directly tells us the true earthquake size information. It is the great advantage of the GPS compared with the seismometer even though the signal-to-noise ratio is lower than it. Based on these backgrounds, we newly developed an algorithm to detect/estimate static ground displacement due to earthquake faulting from real time kinematic GPS (RTK-GPS) time series for quasi real-time determination of seismic fault model. We use the method using comparison between short-term and long-term average, which is generally used for automatic detection of seismic waves. Before its practical application, we assessed the noise property of the RTK-GPS time series with various conditions such as baseline lengths, GPS satellites ephemerides, etc., with analysis software "RTKLIB 2.4.0" [http://www.rtklib.com] to show that the ultra-rapid ephemerides distributed by the international GNSS Service result in enough precision for the crustal deformation monitoring with long baselines up to 1,000 km. We applied the algorithm to the GPS data obtained in the Tohoku Earthquake to assess its ability of event detection and performance of fault model estimation. The maximum baseline length is about 900 km. Detection and calculation of the coseismic displacements finished at all sites within about 4.5 min from origin time. Estimation of parameters of a rectangular fault with a uniform slip was also carried out every 20 sec to give the final earthquake magnitude reaching Mw 8.7, which is close to actual one (9.0). Once the fault model is estimated, tsunami waveforms can be synthesized within 1 min by using pre-computed tsunami Green's functions for initial displacement of elementary sea-surface sources [Tsushima et al., Ocean Science Meeting, 2010]. The calculated waveforms show good agreement with the observed tsunami both in arrival times and wave heights at coastal tide gauge stations in near field. In the Tohoku earthquake, tsunami height calculation based on seismic fault model was capable within 6 min from the origin time. These tsunami predictions can be provided 20 min before the actual tsunami attack in this case. The time in advance can save people in the coastal area by providing enough time for evacuation.

  3. Rapid, decimeter-resolution fault zone topography mapped with Structure from Motion

    NASA Astrophysics Data System (ADS)

    Johnson, K. L.; Nissen, E.; Saripalli, S.; Arrowsmith, R.; McGarey, P.; Scharer, K. M.; Williams, P. L.

    2013-12-01

    Recent advances in the generation of high-resolution topography have revolutionized our ability to detect subtle geomorphic features related to ground-rupturing earthquakes. Currently, the most popular topographic mapping methods are airborne Light Detection And Ranging (LiDAR) and terrestrial laser scanning (TLS). Though powerful, these laser scanning methods have some inherent drawbacks: airborne LiDAR is expensive and can be logistically complicated, while TLS is time consuming even for small field sites and suffers from patchy coverage due to its restricted field-of-view. An alternative mapping technique, called Structure from Motion (SfM), builds upon traditional photogrammetry to reproduce the topography and texture of a scene from photographs taken at varying viewpoints. The improved availability of cheap, unmanned aerial vehicles (UAVs) as camera platforms further expedites data collection by covering large areas efficiently with optimal camera angles. Here, we introduce a simple and affordable UAV- or balloon-based SfM mapping system which can produce dense point clouds and sub-decimeter resolution digital elevation models (DEMs) registered to geospatial coordinates using either the photograph's GPS tags or a few ground control points across the scene. The system is ideally suited for studying ruptures of prehistoric, historic, and modern earthquakes in areas of sparse or low-lying vegetation. We use two sites from southern California faults to illustrate. The first is the ~0.1 km2 Washington Street site, located on the Banning strand of the San Andreas fault near Thousand Palms. A high-resolution DEM with ~700 point/m2 was produced from 230 photos collected on a balloon platform flying at 50 m above the ground. The second site is the Galway Lake Road site, which spans a ~1 km strip of the 1992 Mw 7.3 Landers earthquake on the Emerson Fault. The 100 point/m2 DEM was produced from 267 photos taken with a balloon platform at a height of 60 m above the ground. We compare our SfM results to existing airborne LiDAR or TLS datasets. Each SfM survey required less than 2 hours for setup and data collection, an allotment much lower than that required for TLS data collection, given the size of the sites. Processing time is somewhat slower, but depends on the quality of the DEM desired and is almost fully automated. The SfM point cloud densities we present are comparable to TLS but exceed the density of most airborne LiDAR and the orthophotos (texture maps) from the SfM are valuable complements to the DEMs. The SfM topography illuminates features along the faults that can be used to measure offsets from past ruptures, offering the potential to enhance regional seismic hazard analyses.

  4. The role of dyking and fault control in the rapid onset of eruption at Chaitén Volcano, Chile

    USGS Publications Warehouse

    Wicks, C.; De La, Llera, J. C.; Lara, L.E.; Lowenstern, J.

    2011-01-01

    Rhyolite is the most viscous of liquid magmas, so it was surprising that on 2 May 2008 at Chaitén Volcano, located in Chile’s southern Andean volcanic zone, rhyolitic magma migrated from more than 5 km depth in less than 4 hours and erupted explosively with only two days of detected precursory seismic activity. The last major rhyolite eruption before that at Chaitén was the largest volcanic eruption in the twentieth century, at Novarupta volcano, Alaska, in 1912. Because of the historically rare and explosive nature of rhyolite eruptions and because of the surprisingly short warning before the eruption of the Chaitén volcano, any information about the workings of the magmatic system at Chaitén, and rhyolitic systems in general, is important from both the scientific and hazard perspectives. Here we present surface deformation data related to the Chaitén eruption based on radar interferometry observations from the Japan Aerospace Exploration Agency (JAXA) DAICHI (ALOS) satellite. The data on this explosive rhyolite eruption indicate that the rapid ascent of rhyolite occurred through dyking and that melt segregation and magma storage were controlled by existing faults.

  5. The role of dyking and fault control in the rapid onset of eruption at Chaitén volcano, Chile.

    PubMed

    Wicks, Charles; de la Llera, Juan Carlos; Lara, Luis E; Lowenstern, Jacob

    2011-10-20

    Rhyolite is the most viscous of liquid magmas, so it was surprising that on 2 May 2008 at Chaitén Volcano, located in Chile's southern Andean volcanic zone, rhyolitic magma migrated from more than 5 km depth in less than 4 hours (ref. 1) and erupted explosively with only two days of detected precursory seismic activity. The last major rhyolite eruption before that at Chaitén was the largest volcanic eruption in the twentieth century, at Novarupta volcano, Alaska, in 1912. Because of the historically rare and explosive nature of rhyolite eruptions and because of the surprisingly short warning before the eruption of the Chaitén volcano, any information about the workings of the magmatic system at Chaitén, and rhyolitic systems in general, is important from both the scientific and hazard perspectives. Here we present surface deformation data related to the Chaitén eruption based on radar interferometry observations from the Japan Aerospace Exploration Agency (JAXA) DAICHI (ALOS) satellite. The data on this explosive rhyolite eruption indicate that the rapid ascent of rhyolite occurred through dyking and that melt segregation and magma storage were controlled by existing faults. PMID:22012396

  6. Nanometer quartz grains and rapid cooling melt in fault gouge during earthquake process - observed from the WFSD-1 drilling core sample

    NASA Astrophysics Data System (ADS)

    Wang, H.; Li, H.; Janssen, C.; Wirth, R.

    2014-12-01

    Drilling into active faults is an effective way to get data and materials at depth that help to understand the material properties, physical mechanisms and healing processes of the faults. The Wenchuan earthquake fault scientific drilling project (WFSD) was conducted immediately after the 2008 Wenchuan earthquake (Mw 7.9). The first borehole of the project (WFSD-1) penetrates the Yingxiu-Beichuan fault with a final depth of 1201.15 m and meet the principal slip zone (PSZ) of Wenchuan earthquake at depth of 589.2 m. About 183.3 m-thick fault rocks are recognized in the WFSD-1 drilling core from 575.7 to 759 m-depth, which was confirmed as the Yingxiu-Beichuan fault zone with a real thickness of about 100 m due to the borehole inclination of 11°. In this research we got samples from WFSD-1 drilling core at the depth of 732.4-732.8 m, in which black gouge, gray gouge, fine-grained fault breccia and coarse-grained fault breccia layers can be distinguished clearly. Slickensides were developed in the surface of the black gouge layer. The protolith of this segment is sandstone. Based on detailed microstructural analysis using electron optical microscope, scanning electron microscope (SEM) and transmission electron microscope (TEM). An about 1 mm-thick amorphous material layer containing small quartz grains was observed. Circles with different densities were observed in the amorphous material indicate a melt-origin. Cracks are developed in the amorphous material, which are suggested to be caused by general volume reduction as a result of rapid cooling contraction. TEM-EDX analysis of the amorphous material indicates mainly feldspar composition, implying the melting temperature was >1230℃, while quartz grains did not melt indicating a temperature <1700℃. Nano-scale quartz grains were observed in a very small layer showing a different structure at the edge of the amorphous layer, indicating that nano quartz grains were formed by the comminution during earthquake, which is very important in earthquake energy budgets calculation. These microstructural analysis results reveal that the amorphous layer may formed by rapid cooling of the frictional melt material caused by high-velocity slip during a large earthquake, and fluid flow may played an important role in the rapid cooling process.

  7. Clastic dikes of Heart Mountain fault breccia, northwestern Wyoming, and their significance

    USGS Publications Warehouse

    Pierce, W.G.

    1979-01-01

    Structural features in northwestern Wyoming indicate that the Heart Mountain fault movement was an extremely rapid, cataclysmic event that created a large volume of carbonate fault breccia derived entirely from the lower part of the upper plate. After fault movement had ceased, much of the carbonate fault breccia, here called calcibreccia, lay loose on the resulting surface of tectonic denudation. Before this unconsolidated calcibreccia could be removed by erosion, it was buried beneath a cover of Tertiary volcanic rocks: the Wapiti Formation, composed of volcanic breccia, poorly sorted volcanic breccia mudflows, and lava flows, and clearly shown in many places by inter lensing and intermixing of the calcibreccia with basal volcanic rocks. As the weight of volcanic overburden increased, the unstable water-saturated calcibreccia became mobile and semifluid and was injected upward as dikes into the overlying volcanic rocks and to a lesser extent into rocks of the upper plate. In some places the lowermost part of the volcanic overburden appears to have flowed with the calcibreccia to form dike like bodies of mixed volcanic rock and calcibreccia. One calcibreccia dike even contains carbonized wood, presumably incorporated into unconsolidated calcibreccia on the surface of tectonic denudation and covered by volcanic rocks before moving upward with the dike. Angular xenoliths of Precambrian rocks, enclosed in another calcibreccia dike and in an adjoining dikelike mass of volcanic rock as well, are believed to have been torn from the walls of a vent and incorporated into the basal part of the Wapiti Formation overlying the clastic carbonate rock on the fault surface. Subsequently, some of these xenoliths were incorporated into the calcibreccia during the process of dike intrusion. Throughout the Heart Mountain fault area, the basal part of the upper-plate blocks or masses are brecciated, irrespective of the size of the blocks, more intensely at the base and in places extending upward for several tens of meters. North of Republic Mountain a small 25-m-high upper-plate mass, brecciated to some degree throughout, apparently moved some distance along the Heart Mountain fault as brecciated rock. Calcibreccia dikes intrude upward from the underlying 2 m of fault breccia into the lower part of the mass and also from its top into the overlying volcanic rocks; an earthquake-related mechanism most likely accounts for the observed features of this deformed body. Calcibreccia dikes are more common within the bedding-plane phase of the Heart Mountain fault but also occur in its transgressive and former land-surface phases. Evidence that the Wapiti Formation almost immediately buried loose, unconsolidated fault breccia that was the source of the dike rock strongly suggests a rapid volcanic deposition over the area in which clastic dikes occur, which is at least 75 km long. Clastic dikes were injected into both the upper-plate and the volcanic rocks at about the same time, after movement on the Heart Mouuntain fault had ceased, and therefore do not indicate a fluid-flotation mechanism for the Heart Mountain fault. The difference between contacts of the clastic dikes with both indurated and unconsolidated country rock is useful in field mapping at localities where it is difficult to distinguish between volcanic rocks of the Cathedral Cliffs and Lamar River Formations, and the Wapiti Formation. Thus, calcibreccia dikes in the Cathedral Cliffs and Lamar River Formations show a sharp contact because the country rock solidified prior to fault movement, whereas calcibreccia dikes in the Wapiti Formation in many instances show a transitional or semifluid contact because the country rock was still unconsolidated or semifluid at the time of dike injection.

  8. Evidence for rapid displacement on Himalayan normal faults and the importance of tectonic denudation in the evolution of mountain ranges

    NASA Astrophysics Data System (ADS)

    Hodges, Kip; Bowring, Samuel; Davidek, Kathleen; Hawkins, David; Krol, Michael

    1998-06-01

    East-striking, low-angle normal faults of the South Tibetan detachment system have played an important role in exposing the high-grade metamorphic core of the Himalayan orogen. In the Mount Everest region of southern Tibet, granites both pre- and postdate an important fault of the system, the Qomolangma detachment. New U-Pb and 40Ar/39Ar geochronologic data for these rocks constrain the age of brittle faulting to between 16.67 ± 0.04 and 16.37 ± 0.40 Ma, significantly expanding the known age range for extension in the central Himalaya (widely regarded as ca. 20 22 Ma). More importantly, they indicate an average displacement rate of ≥47 mm/yr and a consequent tectonic unroofing rate of ≥8.2 mm/yr. Such unroofing is faster than all but the highest estimates of combined physical and chemical erosion rates in mountainous regions, suggesting that large-displacement normal faulting can be an extremely efficient agent of mass redistribution in orogenic systems.

  9. The Grammar School at the Cathedral of the Canary Islands (1563-1851)

    ERIC Educational Resources Information Center

    Vera-Cazorla, Maria Jesus

    2013-01-01

    From 1563 until the death of the last teacher in 1851, there was a prebendary in the Cathedral of the Canary Islands in charge of the education of children. In fact, it could be said that this prebendary was the only continuous secondary school teacher there was in the Canary Islands until the beginning of the nineteenth century when the High…

  10. An App for the Cathedral in Freiberg--An Interdisciplinary Project Seminar

    ERIC Educational Resources Information Center

    Kröber, Cindy; Münster, Sander

    2014-01-01

    This project seminar aims at creating and evaluating a manual for interdisciplinary projects as part of a learning process. Working together, pedagogies and students from different disciplines assess tools and recommendations for successful collaborations while developing an app for the cathedral in Freiberg. As part of the project the students…

  11. Constable's "Salisbury Cathedral" in English Class: A Case Study Argument for Blended Curriculum.

    ERIC Educational Resources Information Center

    Traubitz, Nancy

    1995-01-01

    Contends that, although the Eurocentric focus in art and literature currently may be out of favor, the lack of a cultural background may hurt students' scores on standardized tests. Describes a teaching plan based on artist John Constable's painting, "Salisbury Cathedral from the Bishop's Garden." (CFR)

  12. The effect of air pollution on the stone decay of the Cologne Cathedral

    NASA Astrophysics Data System (ADS)

    Graue, B.; Siegesmund, S.; Licha, T.; Simon, K.; Oyhantcabal, P.; Middendorf, B.

    2012-04-01

    Different building stones of the Cologne Cathedral show a large variation of weathering phenomena. The Drachenfels trachyte, which was the construction material for the medieval part of the cathedral, shows significant surface deterioration, back-weathering coexisting with flaking, crumbling or the massive formation of gypsum crusts. Wolff (1992) first mentioned the negative interferences between the Schlaitdorfer sandstone and the Londorfer basalt lava or the Drachenfels trachyte and the Krensheimer muschelkalk. Crust formation on limestone, sandstone, and volcanic rock from the Cologne Cathedral as well as from the Xanten and Altenberg Cathedral are investigated. These three buildings are located in different areas and exposed to varying industrial, urban, and rural environmental situations. The material investigated range from dark grey to black framboidal crusts. This 3 to 10 mm thick cauliflower-like form of gypsum crust incorporates particles from the pollution fluxes. It covers the stone surface and mainly occurs at sites protected from wind and direct rain. Secondly, thin laminar black crusts trace the stone surface and may cover complete sections of the building's structure not necessarily preferring protected sites. This kind of crust seems to have very strong bonds between the thin black crust and the stone surface. Major and trace element distribution show an enrichment of sulfur, indicating the presence of gypsum, lead and other typical pollutants (arsenic, antimony, bismuth, tin etc.), which generally can be linked to traffic and industry. This indicates that even though the SO2 emission has decreased due to i.e. stronger regulations of waste incineration plants and the ban of leaded petrol, the pollutants are still present in the crusts on the building stones. From systematic SEM observations it becomes evident that the total amount of pollution is less pronounced in the Altenberg and Xanten Cathedrals as compared with the Cologne Cathedral. The formation of gypsum occurs at lower amounts in Altenberg, which correlates well with the measured SO2 content. On the other hand, the increasing H2O content in the trachyte and the crusts correlates well with an increasing phyllosilicate formation. Through the combination of different analytical techniques it was possible to clearly distinguish samples from the industrial or rural environment. If the data is compared to actual pollutant emissions, the analyzed samples imply present but also past pollution fluxes. Thus, the soiled zones of the built environment can function as environmental indicators.

  13. Listener perception of and acoustic differences between girl and boy choristers in an English cathedral choir

    NASA Astrophysics Data System (ADS)

    Howard, David; Welch, Graham

    2005-09-01

    For centuries, boy choristers have been singing the top (treble) line in English cathedrals. Girl choristers were first admitted in 1991, and there is a long-running debate as to whether they can carry out this role appropriately. This paper will detail the results from two listening experiments designed to establish whether or not listeners can tell the difference between girl and boy choristers singing the top line in cathedral music. In the first experiment, 189 listeners took part and on average they were able to tell the difference 60% of the time; this was statistically significant over chance. The results suggested that repertoire played a significant part in this ability, and the second experiment was carried out in which the boys and girls sang the same repertoire. Nearly 170 listeners have completed this experiment and, on average, they are making guesses (correct 52% of the time). The paper will discuss the acoustic differences between the stimuli with respect to the singing of boy and girl choristers, while placing the discussion in the context of the English cathedral tradition.

  14. Integration of constrained electrical and seismic tomographies to study the landslide affecting the cathedral of Agrigento

    NASA Astrophysics Data System (ADS)

    Capizzi, P.; Martorana, R.

    2014-08-01

    The Cathedral of Saint Gerland, located on the top of the hill of Agrigento, is an important historical church, which dates back to the Arab-Norman period (XI century). Unfortunately throughout its history the Cathedral and the adjacent famous Archaeological Park of the ‘Valley of the Temples’ have been affected by landslides. In this area the interleaving of calcarenites, silt, sand and clay is complicated by the presence of dislocated rock blocks and cavities and by a system of fractures partly filled with clay or water. Integrated geophysical surveys were carried out on the north side of the hill, on which the Cathedral of Agrigento is founded, to define lithological structures involved in the failure process. Because of the landslide, the cathedral has been affected by fractures, which resulted in the overall instability of the structure. Along each of four footpaths a combination of 2D electrical resistivity tomographies (ERT) and 2D seismic refraction tomographies (SRT) was performed. Moreover, along two of these footpaths microtremor (HVSR) and surface wave soundings (MASW) were carried out to reconstruct 2D sections of shear waves velocity. Furthermore a 3D electrical resistivity tomography was carried out in a limited area characterized by gentle slopes. After a preliminary phase, in which the data were processed independently, a subsequent inversion of seismic and electrical data was constrained with stratigraphic information obtained from geognostic continuous core boreholes located along the geophysical lines. This process allowed us to significantly increase the robustness of the geophysical models. The acquired data were interpolated to construct 3D geophysical models of the electrical resistivity and of the P-wave velocity. The interpolation algorithm took into account the average direction and immersion of geological strata. Results led to a better understanding of the complexity of the subsoil in the investigated area. The use of integrated geophysical techniques allowed us to understand the sliding processes that affect the slope delimiting the possible rock volume affected by the sliding. These results should be useful to define the works to consolidate the landslides affecting the slope on which the Cathedral is founded and the hill inside the Archaeological Park.

  15. The South Fork detachment fault, Park County, Wyoming: discussion and reply ( USA).

    USGS Publications Warehouse

    Pierce, W.G.

    1986-01-01

    Blackstone (1985) published an interpretation of South form detachment fault and related features. His interpretation of the area between Castle and Hardpan transverse faults is identical to mine of 1941. Subsequent detailed mapping has shown that the structure between the transverse faults is more complicated than originally envisioned and resurrected by Blackstone. The present paper describes and discusses geologic features that are the basis for my interpretations; also discussed are differences between my interpretations and those of Blackstone. Most data are shown on the geologic map of the Wapiti Quadrangle (Pierce and Nelson, 1969). Blackstone's 'allochthonous' masses are part of the South Form fault. Occurrences of Sundance Formation, which he interpreted as the upper plate of his 'North Fork fault', are related to Heart Mountain fault. Volcaniclastic rocks south of Jim Mountain mapped as Aycross Formation by Torres and Gingerich may be Cathedral Cliffs Formation, emplaced by movement of the Heart Mountain fault. - Author

  16. The transmission of masticatory forces and nasal septum: structural comparison of the human skull and Gothic cathedral.

    PubMed

    Hilloowala, Rumy; Kanth, Hrishi

    2007-07-01

    This study extrapolates the transmission of masticatory forces to the cranium based on the architectural principles of Gothic cathedrals. The most significant finding of the study, obtained by analysis of coronal CT scans, is the role of the hard palate, and especially the vomer and the perpendicular plate of the ethmoid in masticatory force transmission. The study also confirms, experimentally, the paths of masticatory forces, cited in literature but based purely on morphological observations. Human skulls and Gothic cathedrals have similar morphological and functional characteristics. The load exerted by the roof of the cathedral is transmitted to the ground by piers and buttresses. These structures also resist the shearing forces exerted by high winds. Similarly, the mid-facial bones of the skull transmit the vertical as well as the lateral masticatory forces from the maxillary dentition to the skull base. The nonload bearing walls and stained glass windows of the cathedral correspond to the translucent wall of the maxilla. The passageway between the aisle and the nave of the cathedral is equivalent to the meatal openings in the lateral wall of the nasal cavity. PMID:17696032

  17. Observation on the recent examination of bones from St David's Cathedral.

    PubMed

    Nokes, L D; Evans, W; Knight, B H; Dent, C

    2000-01-01

    Bones discovered in 1866 walled up in St David's Cathedral, West Wales were thought possibly to be those of St David and his companion St Justinian, both of whom died in the late 6th or early 7th century. Examination and radio carbon dating of the bones suggested that these were not from St David nor St Justinian. Some of the bones could be the remains of St Caradoc, a 12th century hermit. It is likely, however, that the bones are remains of clergy who, for reasons not yet understood, were re-interred into the wall. PMID:10689864

  18. Faulted Barn

    This barn is faulted through the middle; the moletrack is seen in the foreground with the viewer standing on the fault. From the air one can see metal roof panels of the barn that rotated as the barn was faulted....

  19. Polyphase exhumation in the western Qinling Mountains, China: Rapid Early Cretaceous cooling along a lithospheric-scale tear fault and pulsed Cenozoic uplift

    PubMed Central

    Heberer, Bianca; Anzenbacher, Thomas; Neubauer, Franz; Genser, Johann; Dong, Yunpeng; Dunkl, István

    2014-01-01

    The western sector of the Qinling–Dabie orogenic belt plays a key role in both Late Jurassic to Early Cretaceous “Yanshanian” intracontinental tectonics and Cenozoic lateral escape triggered by India–Asia collision. The Taibai granite in the northern Qinling Mountains is located at the westernmost tip of a Yanshanian granite belt. It consists of multiple intrusions, constrained by new Late Jurassic and Early Cretaceous U–Pb zircon ages (156 ± 3 Ma and 124 ± 1 Ma). Applying various geochronometers (40Ar/39Ar on hornblende, biotite and K-feldspar, apatite fission-track, apatite [U–Th–Sm]/He) along a vertical profile of the Taibai Mountain refines the cooling and exhumation history. The new age constraints record the prolonged pre-Cenozoic intracontinental deformation as well as the cooling history mostly related to India–Asia collision. We detected rapid cooling for the Taibai granite from ca. 800 to 100 °C during Early Cretaceous (ca. 123 to 100 Ma) followed by a period of slow cooling from ca. 100 Ma to ca. 25 Ma, and pulsed exhumation of the low-relief Cretaceous peneplain during Cenozoic times. We interpret the Early Cretaceous rapid cooling and exhumation as a result from activity along the southern sinistral lithospheric scale tear fault of the recently postulated intracontinental subduction of the Archean/Palaeoproterozoic North China Block beneath the Alashan Block. A Late Oligocene to Early Miocene cooling phase might be triggered either by the lateral motion during India–Asia collision and/or the Pacific subduction zone. Late Miocene intensified cooling is ascribed to uplift of the Tibetan Plateau. PMID:27065503

  20. 3D modeling of the Strasbourg's Cathedral basements for interdisciplinary research and virtual visits

    NASA Astrophysics Data System (ADS)

    Landes, T.; Kuhnle, G.; Bruna, R.

    2015-08-01

    On the occasion of the millennium celebration of Strasbourg Cathedral, a transdisciplinary research group composed of archaeologists, surveyors, architects, art historians and a stonemason revised the 1966-1972 excavations under the St. Lawrence's Chapel of the Cathedral having remains of Roman and medieval masonry. The 3D modeling of the Chapel has been realized based on the combination of conventional surveying techniques for the network creation, laser scanning for the model creation and photogrammetric techniques for the texturing of a few parts. According to the requirements and the end-user of the model, the level of detail and level of accuracy have been adapted and assessed for every floor. The basement has been acquired and modeled with more details and a higher accuracy than the other parts. Thanks to this modeling work, archaeologists can confront their assumptions to those of other disciplines by simulating constructions of other worship edifices on the massive stones composing the basement. The virtual reconstructions provided evidence in support of these assumptions and served for communication via virtual visits.

  1. Crowning the Cathedral of Florence: Brunelleschi Builds His Dome. A Unit of Study for Grades 7-10.

    ERIC Educational Resources Information Center

    Symcox, Linda

    This unit focuses on a dramatic moment in the Renaissance from about 1420 when Filippo Brunelleschi single handedly created, defined, and engineered a new architecture by building the great dome of the cathedral of Santa Maria del Fiore in Florence. The dome became the symbol of Florence's grandeur during the Renaissance, and a model for great…

  2. The Cathedral and the Bazaar of E-Repository Development: Encouraging Community Engagement with Moving Pictures and Sound

    ERIC Educational Resources Information Center

    Wong, Denis; Shephard, Kerry L.; Phillips, Peter

    2008-01-01

    This paper offers an insight into the development, use and governance of e-repositories for learning and teaching, illustrated by Eric Raymond's bazaar and cathedral analogies and by a comparison of collection strategies that focus on content coverage or on the needs of users. It addresses in particular the processes that encourage and achieve…

  3. Fault finder

    DOEpatents

    Bunch, Richard H.

    1986-01-01

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

  4. Spectrometric investigation of the weathering process affecting historical glasses of León Cathedral, Spain

    NASA Astrophysics Data System (ADS)

    Castro, M. A.; Pereira, F. J.; Aller, A. J.; Littlejohn, D.

    2014-12-01

    Atmospheric pollution plays important roles in the weathering of the historical buildings and glass windows. Samples of white powdered weathering products, recovered during restoration of the stained-glass windows of León Cathedral in Spain, were characterised using a combination of scanning electron microscopy (SEM) with energy dispersive-X ray spectrometry (ED-XRS), Fourier transform-infrared (FT-IR) spectroscopy and Raman spectrometry. The presence of sulphates, and to a lesser extent carbonates, in the white powdered product is clear indication of the participation of atmospheric acidifying gases, particularly SOx, in the weathering process. It is interesting to note that there was no indication of the participation of NOx gases. There was, however, evidence that the putty and mortar used to seal/join the glasses were major sources of the weathering products. In this way, this study suggests sealants more resistant to oxidation, such as silicone- and zirconia-based materials, should be considered for repairing glass windows in historic buildings to avoid exacerbating degradation.

  5. Solar-energy-system performance evaluation, Cathedral Square, Burlington, Vermont, July-December 1981

    SciTech Connect

    Welch, K.M.

    1981-01-01

    The Cathedral Square solar site is a 10-story multiunit apartment building in Vermont. Its active solar energy system is designed to supply 51% of the hot water load, and consists of 1798 square feet of flat plate collectors, 2699-gallon water tank in an enclosed mechanical room on the roof, and two auxiliary natural gas boilers to supply hot water to immersed heat exchanger in an auxiliary storage tank. The measured solar fraction was only 28%, not 51%, which, it is concluded, is an unreasonable expectation. Other performance data include the solar savings ratio, conventional fuel savings, system performance factor, and solar system coefficient of performance. Monthly performance data are given for the solar system overall, and for the collector, storage, and hot water subsystems. Also included are insolation data, typical storage fluid temperatures, domestic hot water consumption, and solar heat exchangers inlet/outlet temperatures, and typical domestic hot water subsystem temperatures. In addition, the system operating sequence and solar energy utilization are given. Appended are a system description, performance evaluation techniques, long-term weather data. (LEW)

  6. Ancient descriptions of movement disorders: Cathedral el Burgo de Osma (Soria, Spain).

    PubMed

    Garcia Ruiz, Pedro J; Ruiz Ezquerro, Juan J; Garcia Torres, Araceli; Fanjul, Samira

    2006-06-01

    El Burgo de Osma (Soria, Spain) offers one of the best preserved medieval structures in Spain. The interior of the building conserves abundant samples of Romanesque art, and the tomb in polychromatic stone of the founder, San Pedro de Osma. We have classified those pieces of art that could represent descriptions of movement disorders. In the main façade of the Cathedral, several statues representing prophets can be seen one of them is clearly different to the rest. This statue represents a man with abnormal cervical posture characterized by right rotation, head tilt and elevation of right shoulder. The tomb includes several statues representing fragments of the life of San Pedro de Osma. Some of these figures show movement disorders. First, a woman with a baby in her arms who has marked head tilt to the left. Second a peasant without hands, perhaps amputated, this man has a head tilt to the right. We suggest that in the latter case ergotism can explain both manifestations: peripheral vascular disease leading to amputation, and cervical dystonia.Finally, a statue of polychromatic wood represents a priest with stooped posture, half open mouth, staring expression and a very notorious anterocollis. The author probably depicted a man with parkinsonism. PMID:16511653

  7. Monitoring of the Heat and Moisture Transport through Walls of St. Martin Cathedral Tower in Bratislava

    NASA Astrophysics Data System (ADS)

    Kubičár, Ľudovít; Hudec, Ján; Fidríková, Danica; Štofanik, Vladimír; Dieška, Peter; Vretenár, Viliam

    2014-05-01

    Historic monuments are subject to degradation due to exposition to surrounding meteorological conditions and groundwater. Construction of buildings consists of the plaster and material components that have porous structure. Processes like heat transport, moisture diffusion, moisturizing and drying; freezing and thawing can be found in such structures depending on environmental conditions. Monitoring of the temperature - moisture regime gives a picture on the processes running in the structure. Long term monitoring of the tower of St. Martin Cathedral in Bratislava have been performed under window sill of the belfry in exterior in south orientation. Principle of the hot-ball method is used for monitoring of the temperature and thermal conductivity. The thermal conductivity of the porous system depends on the pore content. Moisture sensors are constructed from the parent material in a form of cylinder. Sensors are calibrated for dry and water saturated stage prior installation in the walls. Monitoring has been carried out in plaster and in the masonry in a distance about 10 cm from the wall surface, where sensors are installed. Information on temperature, moisture and thermal conductivity can be gained from measured signal. Use of two sensors allows estimation on heat and moisture transport through the wall. Monitoring has been performed in the period from April 2013 up to July 2013. Monitored data are correlated to the meteorological data. Details of various effects will be discussed.

  8. Fault diagnosis

    NASA Technical Reports Server (NTRS)

    Abbott, Kathy

    1990-01-01

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

  9. Fault mechanics

    SciTech Connect

    Segall, P. )

    1991-01-01

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

  10. Linking groundwater pollution to the decay of 15th-century sculptures in Burgos Cathedral (northern Spain).

    PubMed

    Gázquez, Fernando; Rull, Fernando; Medina, Jesús; Sanz-Arranz, Aurelio; Sanz, Carlos

    2015-10-01

    Precipitation of salts-mainly hydrated Mg-Na sulfates-in building materials is rated as one of the most severe threats to the preservation of our architectural and cultural heritage. Nevertheless, the origin of this pathology is still unknown in many cases. Proper identification of the cause of damage is crucial for correct planning of future restoration actions. The goal of this study is to identify the source of the degradation compounds that are affecting the 15th-century limestone sculptures that decorate the retro-choir of Burgos Cathedral (northern Spain). To this end, detailed characterization of minerals by in situ (Raman spectroscopy) and laboratory techniques (XRD, Raman and FTIR) was followed by major elements (ICP and IC) and isotopic analysis (δ(34)S and δ(15)N) of both the mineral phases precipitated on the retro-choir and the dissolved salts in groundwater in the vicinity of the cathedral. The results reveal unequivocal connection between the damage observed and capillary rise of salts-bearing water from the subsoil. The multianalytical methodology used is widely applicable to identify the origin of common affections suffered by historical buildings and masterpieces. PMID:26018286

  11. Rule-based fault diagnosis of hall sensors and fault-tolerant control of PMSM

    NASA Astrophysics Data System (ADS)

    Song, Ziyou; Li, Jianqiu; Ouyang, Minggao; Gu, Jing; Feng, Xuning; Lu, Dongbin

    2013-07-01

    Hall sensor is widely used for estimating rotor phase of permanent magnet synchronous motor(PMSM). And rotor position is an essential parameter of PMSM control algorithm, hence it is very dangerous if Hall senor faults occur. But there is scarcely any research focusing on fault diagnosis and fault-tolerant control of Hall sensor used in PMSM. From this standpoint, the Hall sensor faults which may occur during the PMSM operating are theoretically analyzed. According to the analysis results, the fault diagnosis algorithm of Hall sensor, which is based on three rules, is proposed to classify the fault phenomena accurately. The rotor phase estimation algorithms, based on one or two Hall sensor(s), are initialized to engender the fault-tolerant control algorithm. The fault diagnosis algorithm can detect 60 Hall fault phenomena in total as well as all detections can be fulfilled in 1/138 rotor rotation period. The fault-tolerant control algorithm can achieve a smooth torque production which means the same control effect as normal control mode (with three Hall sensors). Finally, the PMSM bench test verifies the accuracy and rapidity of fault diagnosis and fault-tolerant control strategies. The fault diagnosis algorithm can detect all Hall sensor faults promptly and fault-tolerant control algorithm allows the PMSM to face failure conditions of one or two Hall sensor(s). In addition, the transitions between health-control and fault-tolerant control conditions are smooth without any additional noise and harshness. Proposed algorithms can deal with the Hall sensor faults of PMSM in real applications, and can be provided to realize the fault diagnosis and fault-tolerant control of PMSM.

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

    SciTech Connect

    Boles, James

    2013-05-24

    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.

  13. Seismicity and fault geometry of the San Andreas fault around Parkfield, California and their implications

    NASA Astrophysics Data System (ADS)

    Kim, Woohan; Hong, Tae-Kyung; Lee, Junhyung; Taira, Taka'aki

    2016-05-01

    Fault geometry is a consequence of tectonic evolution, and it provides important information on potential seismic hazards. We investigated fault geometry and its properties in Parkfield, California on the basis of local seismicity and seismic velocity residuals refined by an adaptive-velocity hypocentral-parameter inversion method. The station correction terms from the hypocentral-parameter inversion present characteristic seismic velocity changes around the fault, suggesting low seismic velocities in the region east of the fault and high seismic velocities in the region to the west. Large seismic velocity anomalies are observed at shallow depths along the whole fault zone. At depths of 3-8 km, seismic velocity anomalies are small in the central fault zone, but are large in the northern and southern fault zones. At depths > 8 km, low seismic velocities are observed in the northern fault zone. High seismicity is observed in the Southwest Fracture Zone, which has developed beside the creeping segment of the San Andreas fault. The vertical distribution of seismicity suggests that the fault has spiral geometry, dipping NE in the northern region, nearly vertical in the central region, and SW in the southern region. The rapid twisting of the fault plane occurs in a short distance of approximately 50 km. The seismic velocity anomalies and fault geometry suggest location-dependent piecewise faulting, which may cause the periodic M6 events in the Parkfield region.

  14. Fault interactions and growth in an outcrop-scale system

    NASA Astrophysics Data System (ADS)

    Nicol, Andy; Walsh, John; Childs, Conrad; Manzocchi, Tom; Schoepfer, Martin

    2015-04-01

    Fault geometries and strike-slip displacements in a moderately dipping (~50°) multi-layer sequence have been analysed to constrain the evolution of an outcrop-scale fault system in coastal New Zealand. Displacements and geometries of small faults (lengths 1-200 m and maximum displacements 0.007-3 m) were sampled from a horizontal shore platform up to 120 m wide and 1.5 km long with near 100% exposure. Displacement profiles have variable shapes that mainly reflect fault interactions, with individual faults being both hard- and soft-linked. Variable displacement profiles produce an average profile for all faults that is near-triangular, with displacement gradients (and displacement-length ratios) increasing by an order of magnitude from smallest to largest faults. Within fault zones these gradients are accompanied by secondary faults, which are typically of greatest density close to fault intersections, in relay zones and at fault tips. Horsetail and synthetic splays confined to the regions around fault tips are incompatible with gradual fault propagation for the duration of growth. Instead, fault displacements and tip geometries are consistent with growth initially dominated by fault propagation followed by displacement accumulation and approximately stationary fault tips. Retardation of propagation is thought to arise due to fault interactions and associated reduction of tip stresses, with the early change from propagation- to displacement-dominated growth stages produced by fault-system saturation (i.e., all faults are interacting). Initial rapid fault propagation succeeded by displacement-dominated growth accounts for different fault types over a range of scales suggesting that this fault growth model has wide application.

  15. Potential fields of the Hollister fault zone

    SciTech Connect

    Fletcher, C.D.; Lawrence, D.P. . Dept. of Geology)

    1992-01-01

    The Hollister fault zone outcrops in southeastern Virginia and in northeastern North Carolina and is an important constituent of the eastern Piedmont fault system. The Hollister fault zone is a steeply westward dipping, north-south trending D[sub 3] ductile mylonite zone that has an average width of less than 1/2 km. It is a dextral strike-slip fault and represents the boundary between the Spring Hope and Roanoke Rapids terranes. Some Alleghanian fault motion has been recorded in foliated parts of the Butterwood Creek granite (Rb-87/Sr-86 whole-rock age date of 292 [+-] 30 Ma). The fault cuts the western side of the Butterwood Creek pluton, skirts the west side of the Rocky Mount pluton, passes south through the city of Wilson, and continues to Goldsboro, N.C.. The southern limit of exposure is near Rocky Mount, south of which the fault is obscured by Coastal Plain sediments. Only magnetic and gravity data can be used to suggest a possible continuation for the unexposed segment of the fault zone. Detailed gravity data and magnetic data profiles were collected in the northern and central parts of Halifax county and in the southern part of Wilson county. Gravity data collected along trend of the fault reveal a steep gravity gradient across the mylonite zone and minor anomalies associated with faulted slices of varying densities. Aeromagnetic maps show truncation of anomalies by the fault or presence of magnetic highs along the fault zone. Ground magnetic profiles exhibit clusters of magnetic highs within the mylonite zone. The profiles were modeled to reveal fault geometry and to investigate the geophysical characteristics of adjacent terranes. Integrating gravity and magnetic data established geophysical signatures of the mylonite zone that may be used to trace the fault through obscured areas.

  16. Early weakening processes inside thrust fault

    NASA Astrophysics Data System (ADS)

    Lacroix, B.; Tesei, T.; Oliot, E.; Lahfid, A.; Collettini, C.

    2015-07-01

    Observations from deep boreholes at several locations worldwide, laboratory measurements of frictional strength on quartzo-feldspathic materials, and earthquake focal mechanisms indicate that crustal faults are strong (apparent friction μ ≥ 0.6). However, friction experiments on phyllosilicate-rich rocks and some geophysical data have demonstrated that some major faults are considerably weaker. This weakness is commonly considered to be characteristic of mature faults in which rocks are altered by prolonged deformation and fluid-rock interaction (i.e., San Andreas, Zuccale, and Nankai Faults). In contrast, in this study we document fault weakening occurring along a marly shear zone in its infancy (<30 m displacement). Geochemical mass balance calculation and microstructural data show that a massive calcite departure (up to 50 vol %) from the fault rocks facilitated the concentration and reorganization of weak phyllosilicate minerals along the shear surfaces. Friction experiments carried out on intact foliated samples of host marls and fault rocks demonstrated that this structural reorganization lead to a significant fault weakening and that the incipient structure has strength and slip behavior comparable to that of the major weak faults previously documented. These results indicate that some faults, especially those nucleating in lithologies rich of both clays and high-solubility minerals (such as calcite), might experience rapid mineralogical and structural alteration and become weak even in the early stages of their activity.

  17. Fault slip distribution and fault roughness

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

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

  18. Fault damage zones

    NASA Astrophysics Data System (ADS)

    Kim, Young-Seog; Peacock, David C. P.; Sanderson, David J.

    2004-03-01

    Damage zones show very similar geometries across a wide range of scales and fault types, including strike-slip, normal and thrust faults. We use a geometric classification of damage zones into tip-, wall-, and linking-damage zones, based on their location around faults. These classes can be sub-divided in terms of fault and fracture patterns within the damage zone. A variety of damage zone structures can occur at mode II tips of strike-slip faults, including wing cracks, horsetail fractures, antithetic faults, and synthetic branch faults. Wall damage zones result from the propagation of mode II and mode III fault tips through a rock, or from damage associated with the increase in slip on a fault. Wall damage zone structures include extension fractures, antithetic faults, synthetic faults, and rotated blocks with associated triangular openings. The damage formed at the mode III tips of strike-slip faults (e.g. observed in cliff sections) are classified as wall damage zones, because the damage zone structures are distributed along a fault trace in map view. Mixed-mode tips are likely to show characteristics of both mode II and mode III tips. Linking damage zones are developed at steps between two sub-parallel faults, and the structures developed depend on whether the step is extensional or contractional. Extension fractures and pull-aparts typically develop in extensional steps, whilst solution seams, antithetic faults and synthetic faults commonly develop in contractional steps. Rotated blocks, isolated lenses or strike-slip duplexes may occur in both extensional and contractional steps. Damage zone geometries and structures are strongly controlled by the location around a fault, the slip mode at a fault tip, and by the evolutionary stage of the fault. Although other factors control the nature of damage zones (e.g. lithology, rheology and stress system), the three-dimensional fault geometry and slip mode at each tip must be considered to gain an understanding of damage zones around faults.

  19. Fault zone fabric and fault weakness.

    PubMed

    Collettini, Cristiano; Niemeijer, Andr; Viti, Cecilia; Marone, Chris

    2009-12-17

    Geological and geophysical evidence suggests that some crustal faults are weak compared to laboratory measurements of frictional strength. Explanations for fault weakness include the presence of weak minerals, high fluid pressures within the fault core and dynamic processes such as normal stress reduction, acoustic fluidization or extreme weakening at high slip velocity. Dynamic weakening mechanisms can explain some observations; however, creep and aseismic slip are thought to occur on weak faults, and quasi-static weakening mechanisms are required to initiate frictional slip on mis-oriented faults, at high angles to the tectonic stress field. Moreover, the maintenance of high fluid pressures requires specialized conditions and weak mineral phases are not present in sufficient abundance to satisfy weak fault models, so weak faults remain largely unexplained. Here we provide laboratory evidence for a brittle, frictional weakening mechanism based on common fault zone fabrics. We report on the frictional strength of intact fault rocks sheared in their in situ geometry. Samples with well-developed foliation are extremely weak compared to their powdered equivalents. Micro- and nano-structural studies show that frictional sliding occurs along very fine-grained foliations composed of phyllosilicates (talc and smectite). When the same rocks are powdered, frictional strength is high, consistent with cataclastic processes. Our data show that fault weakness can occur in cases where weak mineral phases constitute only a small percentage of the total fault rock and that low friction results from slip on a network of weak phyllosilicate-rich surfaces that define the rock fabric. The widespread documentation of foliated fault rocks along mature faults in different tectonic settings and from many different protoliths suggests that this mechanism could be a viable explanation for fault weakening in the brittle crust. PMID:20016599

  20. Faulting in southwest Indiana

    SciTech Connect

    Ault, C.H.; Sullivan, D.M.

    1982-10-01

    Faults of the Wabash Valley Fault System, faults in Perry and Spencer Counties, Indiana, and the Mt. Carmel Fault are of the normal type and high angle and occur as single fault planes or as well-defined compound faults as much as 50 miles long with displacements ranging from a few feet to more than 400 feet. The Wabash faults and those in Perry and Spencer Counties were formally mapped, described, and named for the first time. Although supporting deep-drilling data are sparse, the Wabash and Mt. Carmel faults are probably present at depth, where they may form major structural alignments in basement rocks. No past studies have associated earthquake centers with any of the faults. The Wabash and Perry and Spencer County faults are post-Pennsylvanian and pre-Pleistocene in age. Early movement on the Mt. Carmel Fault is post-Valmeyeran, possibly Chesterian in age. The Wabash faulting is probably related to the regional tectonics that produced the New Madrid disturbance, but it is not a direct continuation of New Madrid faulting across the Rough Creek Fault Zone. The Mt. Carmel Fault may be associated with the hinge line of the eastern shelf of the Illinois Basin.

  1. Loading of the San Andreas fault by flood-induced rupture of faults beneath the Salton Sea

    USGS Publications Warehouse

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

    2011-01-01

    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.

  2. Monitoring of the temperature - moisture regime of critical parts in the tower of the St. Martin Cathedral in Bratislava.

    NASA Astrophysics Data System (ADS)

    Kubicar, L.; Fidríková, D.; Štofanik, V.; Vretenár, V.

    2012-04-01

    Historic monuments are subject to degradation due to exposition to surrounding meteorological conditions and groundwater. Degradation is most often manifested by deterioration of plaster, walls structure and building elements like stones. A significant attention measures are undertaken to prevent degradation of the cultural heritage throughout the world. Our contribution is to monitor the objects for recognition of the critical state when it is necessary to make adjustments to avoid destruction. Buildings consisting from the listed elements belong to porous materials. Moisture diffusion, condensation, etc. attack structure stability of the buildings. Then the moisture diffusion and effects like drying, freezing / thawing belong to the control mechanisms of the degradation. In addition to laboratory experiments concerning the mentioned effects, we simultaneously studied processes by monitoring of the cultural monuments. During monitoring we have identified diffusion of moisture associated with cycle day / night and cycle moisture /drying caused by meteorological precipitation. Long term monitoring is performed in the tower of St. Martin Cathedral in Bratislava under the window sill of the belfry in exterior at three orientations, the north, south and the west. Monitoring is carried out in plaster and in masonry about 10 cm from the wall surface. The thermal conductivity sensors are used for monitoring that operate on the principle of the hot ball method. Then thermal conductivity of porous material is a function of pore content. The sensor has shape of a ball in diameter up to 2 mm in which a heat source as well as a thermometer is integrated into one component. A small heat output is delivered into the surrounding material. The temperature response of the sensor gives information on the thermal conductivity. For use in the preservation of cultural heritage a number of measuring devices have been developed for automatic registration of temperature and moisture in masonry and plaster of monuments.

  3. Scaffoldings Used During The Renovation Of The Metropolitan Cathedral Of St. John The Baptist And St. John The Evangelist In Lublin

    NASA Astrophysics Data System (ADS)

    Pieńko, Michał; Robak, Aleksander; Błazik-Borowa, Ewa

    2015-12-01

    This article describes three cases of scaffolding use as a structure for carrying out a renovation work at the Cathedral in Lublin. In order to achieve optimum access to the object, one used modular scaffolding. This type of scaffold is able to expand in any direction. In addition to the typical use, the scaffold was used as temporary roofing which allowed conducting the work during the winter. Monuments require a detailed approach to the problem of scaffolding. Despite the short period of use we should pay particular attention to the possibility of anchoring scaffoldings. Performing static calculation allows minimizing the number of anchors and used elements.

  4. Fault Mapping in Haiti

    USGS geologist Carol Prentice surveying features that have been displaced by young movements on the Enriquillo fault in southwest Haiti.  The January 2010 Haiti earthquake was associated with the Enriquillo fault....

  5. Quantitative fault seal prediction

    SciTech Connect

    Yielding, G.; Freeman, B.; Needham, D.T.

    1997-06-01

    Fault seal can arise from reservoir/nonreservoir juxtaposition or by development of fault rock having high entry pressure. The methodology for evaluating these possibilities uses detailed seismic mapping and well analysis. A first-order seal analysis involves identifying reservoir juxtaposition areas over the fault surface by using the mapped horizons and a refined reservoir stratigraphy defined by isochores at the fault surface. The second-order phase of the analysis assesses whether the sand/sand contacts are likely to support a pressure difference. We define two types of lithology-dependent attributes: gouge ratio and smear factor. Gouge ratio is an estimate of the proportion of fine-grained material entrained into the fault gouge from the wall rocks. Smear factor methods (including clay smear potential and shale smear factor) estimate the profile thickness of a shale drawn along the fault zone during faulting. All of these parameters vary over the fault surface, implying that faults cannot simply be designated sealing or nonsealing. An important step in using these parameters is to calibrate them in areas where across-fault pressure differences are explicitly known from wells on both sides of a fault. Our calibration for a number of data sets shows remarkably consistent results, despite their diverse settings (e.g., Brent province, Niger Delta, Columbus basin). For example, a shale gouge ratio of about 20% (volume of shale in the slipped interval) is a typical threshold between minimal across-fault pressure difference and significant seal.

  6. The San Andreas Fault

    USGS Publications Warehouse

    Schulz, Sandra S.; Wallace, Robert E.

    1993-01-01

    The presence of the San Andreas fault was brought dramatically to world attention on April 18, 1906, when sudden displacement along the fault produced the great San Francisco earthquake and fire. This earthquake, however, was but one of many that have resulted from episodic displacement along the fault throughout its life of about 15-20 million years.

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

    NASA Technical Reports Server (NTRS)

    Padilla, Peter A.

    1990-01-01

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

  8. Depiction of facial nerve paresis in the gallery of portraits carved in stone by George Matthew the Dalmatian on the Sibenik Cathedral dating from the 15th century.

    PubMed

    Skrobonja, Ante; Culina, Tatjana

    2011-06-01

    The introductory segment of this paper briefly describes George Matthew the Dalmatian, the architect who, between 1441 and 1473, oversaw the construction of the Cathedral of St. James in Sibenik, a city on the Croatian side of the Adriatic coast. Of the most impressive details included in this monumental construction and sculptural flamboyant gothic production infused with distinctive Dalmatian spirit is a frieze of 71 stone and three lion portraits encircling the outer apse wall. From the intriguing amalgamation of portraits of anonymous people this master came across in his surrounding, the fiftieth head in the row has been selected for this occasion. On the face of a younger man the authors have recognized and described pathognomonic right-sided facial nerve paresis. The question posed here is whether this is coincidental or it represents the master's courage, given that instead of famous people in the cathedral he situated not only ordinary people but also those "labelled" and traditionally marginalized, thus, in the most beautiful manner, foreshadowing the forthcoming spirit of Humanism and Renaissance in Croatian and European art. PMID:21755741

  9. Fault tolerant control of spacecraft

    NASA Astrophysics Data System (ADS)

    Godard

    Autonomous multiple spacecraft formation flying space missions demand the development of reliable control systems to ensure rapid, accurate, and effective response to various attitude and formation reconfiguration commands. Keeping in mind the complexities involved in the technology development to enable spacecraft formation flying, this thesis presents the development and validation of a fault tolerant control algorithm that augments the AOCS on-board a spacecraft to ensure that these challenging formation flying missions will fly successfully. Taking inspiration from the existing theory of nonlinear control, a fault-tolerant control system for the RyePicoSat missions is designed to cope with actuator faults whilst maintaining the desirable degree of overall stability and performance. Autonomous fault tolerant adaptive control scheme for spacecraft equipped with redundant actuators and robust control of spacecraft in underactuated configuration, represent the two central themes of this thesis. The developed algorithms are validated using a hardware-in-the-loop simulation. A reaction wheel testbed is used to validate the proposed fault tolerant attitude control scheme. A spacecraft formation flying experimental testbed is used to verify the performance of the proposed robust control scheme for underactuated spacecraft configurations. The proposed underactuated formation flying concept leads to more than 60% savings in fuel consumption when compared to a fully actuated spacecraft formation configuration. We also developed a novel attitude control methodology that requires only a single thruster to stabilize three axis attitude and angular velocity components of a spacecraft. Numerical simulations and hardware-in-the-loop experimental results along with rigorous analytical stability analysis shows that the proposed methodology will greatly enhance the reliability of the spacecraft, while allowing for potentially significant overall mission cost reduction.

  10. Earthquake fault superhighways

    NASA Astrophysics Data System (ADS)

    Robinson, D. P.; Das, S.; Searle, M. P.

    2010-10-01

    Motivated by the observation that the rare earthquakes which propagated for significant distances at supershear speeds occurred on very long straight segments of faults, we examine every known major active strike-slip fault system on land worldwide and identify those with long (> 100 km) straight portions capable not only of sustained supershear rupture speeds but having the potential to reach compressional wave speeds over significant distances, and call them "fault superhighways". The criteria used for identifying these are discussed. These superhighways include portions of the 1000 km long Red River fault in China and Vietnam passing through Hanoi, the 1050 km long San Andreas fault in California passing close to Los Angeles, Santa Barbara and San Francisco, the 1100 km long Chaman fault system in Pakistan north of Karachi, the 700 km long Sagaing fault connecting the first and second cities of Burma, Rangoon and Mandalay, the 1600 km Great Sumatra fault, and the 1000 km Dead Sea fault. Of the 11 faults so classified, nine are in Asia and two in North America, with seven located near areas of very dense populations. Based on the current population distribution within 50 km of each fault superhighway, we find that more than 60 million people today have increased seismic hazards due to them.

  11. Robust Fault Detection

    NASA Technical Reports Server (NTRS)

    Guo, Ten-Huei (Technical Monitor); Collins, Emmanuel G.; Song, Tinglun; Curry, Tramone; Selekwa, Majura

    2003-01-01

    This research used mixed structured singular value theory to develop new estimator (or observer) based approaches to fault detection for dynamic systems. The initial developments were based on minimizing the H-infinity, I-1 and H2 system norms. The resultant fault detection algorithms were each shown to be successful, but the fault detection algorithm based on the I-1 norm was best able to detect abrupt faults. This latter technique was further improved by using fuzzy logic for the fault evaluation. Based on an anomaly observed in this research and apparently ignored in the literature, current research focuses on the determination of a fault using a norm of the change in the residual (the difference between the output of the system and observer) and not simply a norm of the residual itself. This research may lead to a fundamental contribution to research in fault detection and isolation.

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

    NASA Technical Reports Server (NTRS)

    Tsai, Timothy K.; Iyer, Ravishankar K.

    1995-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Tsai, Timothy K.; Iyer, Ravishankar K.

    1994-01-01

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

  14. The initiation of brittle faults in crystalline rock

    NASA Astrophysics Data System (ADS)

    Crider, Juliet G.

    2015-08-01

    Faults in the upper crust initiate from pre-existing (inherited) or precursory (early-formed) structures and typically grow by the mechanical interaction and linkage of these structures. In crystalline rock, rock architecture, composition, cooling, and exhumation influence the initiation of faults, with contrasting styles observed in plutonic rocks, extrusive igneous rocks, and foliated metamorphic rocks. Brittle fault growth in granitic rock is commonly controlled by the architecture of inherited joints or preexisting dikes. In basalt, abundant joints control the surface expression of faulting, and enhanced compliance due to abundant joints leads to folding and deformation asymmetry in the fault zone. Highly reactive mafic minerals likely become rapidly evolving fault rocks. In foliated metamorphic rocks, fault initiation style is strongly influenced by strength anisotropy relative to the principal stress directions, with fracturing favored when the foliation is aligned with the directions of principal stress. The continuity of micas within the foliation also influences the micromechanics of fault initiation. Brittle kink bands are an example of a strain-hardening precursory structure unique to foliated rock. Each of these fault initiation processes produces different initial fault geometry and spatial heterogeneity that influence such properties as fault permeability and seismogenesis.

  15. Isolability of faults in sensor fault diagnosis

    NASA Astrophysics Data System (ADS)

    Sharifi, Reza; Langari, Reza

    2011-10-01

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

  16. How Faults Shape the Earth.

    ERIC Educational Resources Information Center

    Bykerk-Kauffman, Ann

    1992-01-01

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

  17. How Faults Shape the Earth.

    ERIC Educational Resources Information Center

    Bykerk-Kauffman, Ann

    1992-01-01

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

  18. Frictional constraints on crustal faulting

    USGS Publications Warehouse

    Boatwright, J.; Cocco, M.

    1996-01-01

    We consider how variations in fault frictional properties affect the phenomenology of earthquake faulting. In particular, we propose that lateral variations in fault friction produce the marked heterogeneity of slip observed in large earthquakes. We model these variations using a rate- and state-dependent friction law, where we differentiate velocity-weakening behavior into two fields: the strong seismic field is very velocity weakening and the weak seismic field is slightly velocity weakening. Similarly, we differentiate velocity-strengthening behavior into two fields: the compliant field is slightly velocity strengthening and the viscous field is very velocity strengthening. The strong seismic field comprises the seismic slip concentrations, or asperities. The two "intermediate" fields, weak seismic and compliant, have frictional velocity dependences that are close to velocity neutral: these fields modulate both the tectonic loading and the dynamic rupture process. During the interseismic period, the weak seismic and compliant regions slip aseismically, while the strong seismic regions remain locked, evolving into stress concentrations that fail only in main shocks. The weak seismic areas exhibit most of the interseismic activity and aftershocks but can also creep seismically. This "mixed" frictional behavior can be obtained from a sufficiently heterogenous distribution of the critical slip distance. The model also provides a mechanism for rupture arrest: dynamic rupture fronts decelerate as they penetrate into unloaded complaint or weak seismic areas, producing broad areas of accelerated afterslip. Aftershocks occur on both the weak seismic and compliant areas around a fault, but most of the stress is diffused through aseismic slip. Rapid afterslip on these peripheral areas can also produce aftershocks within the main shock rupture area by reloading weak fault areas that slipped in the main shock and then healed. We test this frictional model by comparing the seismicity and the coseismic slip for the 1966 Parkfield, 1979 Coyote Lake, and 1984 Morgan Hill earthquakes. The interevent seismicity and aftershocks appear to occur on fault areas outside the regions of significant slip: these regions are interpreted as either weak seismic or compliant, depending on whether or not they manifest interevent seismicity.

  19. Using Shale Gouge Ratio to Evaluate Offshore Fault Sealing in Eastern Andaman Sea of Burma

    NASA Astrophysics Data System (ADS)

    Ou, Chenghua; Li, Chaochun; He, Jian

    Rapid and accurate fault sealing evaluation is indispensible for high-efficient exploration and exploitation of offshore complex fault block oilfields. Firstly, necessary conditions for fault sealing evaluation of offshore complex fault block oilfields have been put forward. Then, shale gouge ratio method that are suitable for sealing quantitative evaluation have been screened out. Afterwards, the technical procedure has been formulated by integrating static and dynamic data. Finally, case study of the multi-order faults around well A1 in a complex fault block oilfield in eastern Andaman sea of Burma fully demonstrates the practicability, reliability and flexibility of the methods.

  20. Fault detection and fault tolerance in robotics

    NASA Technical Reports Server (NTRS)

    Visinsky, Monica; Walker, Ian D.; Cavallaro, Joseph R.

    1992-01-01

    Robots are used in inaccessible or hazardous environments in order to alleviate some of the time, cost and risk involved in preparing men to endure these conditions. In order to perform their expected tasks, the robots are often quite complex, thus increasing their potential for failures. If men must be sent into these environments to repair each component failure in the robot, the advantages of using the robot are quickly lost. Fault tolerant robots are needed which can effectively cope with failures and continue their tasks until repairs can be realistically scheduled. Before fault tolerant capabilities can be created, methods of detecting and pinpointing failures must be perfected. This paper develops a basic fault tree analysis of a robot in order to obtain a better understanding of where failures can occur and how they contribute to other failures in the robot. The resulting failure flow chart can also be used to analyze the resiliency of the robot in the presence of specific faults. By simulating robot failures and fault detection schemes, the problems involved in detecting failures for robots are explored in more depth.

  1. Relationship Between Mapped Fault Stepovers and Earthquake Fault Planes at Depth

    NASA Astrophysics Data System (ADS)

    Zoback, M.

    2003-12-01

    The San Andreas fault system in the San Francisco Bay area is complex, consisting of several sub-parallel strands with numerous stepovers and bends. Source characterization of future likely earthquakes in the Bay Area requires understanding of the role these fault stepovers and bends play in fault segmentation. Absent aftershocks or microseismicity, it is difficult to determine the subsurface fault geometry. To better understand the role of geometric complexity in controlling earthquake ruptures, I have examined data from several recent major strike-slip earthquakes. The 1995 Mw6.9 Kobe earthquake originated within a 5-km right (dilatational) step in a right-lateral fault and produced a bilateral rupture. Wald (J. Phys. Earth, 1996) showed that the hypocenter occurred at the intersection of the two well-constrained, offset fault planes that were steeply dipping toward each other. A 3-km right step in the San Andreas offshore from the Golden Gate inferred from seismic and potential field data consistently produces normal faulting microearthquakes. The 1906 earthquake with its bilateral rupture is thought to have originated along the offshore segment of the San Andreas fault near the Golden Gate; by analogy with the Kobe earthquake, we have suggested that the 1906 also nucleated within a stepover region. Modeling dynamic rupture propagation constrained by near-fault ground motion records for the 1999 Izmit M7.4 earthquake, led Aochi and Madariaga (BSSA, 2003) to conclude that this rupture was rapid and continuous on a smooth fault structure with a bend of only a few degrees beneath a 5-km right (dilatational) stepover mapped at the surface in the vicinity of Sapanca lake. Similarly, aftershocks and surface faulting of the1995 Mw7.2 Landers earthquake suggest continuous rupture across a 5-km dilatational jog, utilizing an oblique fault connecting the 2 offset fault segments; whereas, the rupture across a second, 2-km dilatational jog appears more diffuse, with no continuous through-going structure (Felzer and Beroza, GRL, 1999). Relocated East Bay microseismicity using the double-difference technique indicates a continuous zone consisting of straight, near-vertical fault planes connecting the Calaveras and Hayward faults across a 5-6 km left (restraining) step (Waldhauser and Ellsworth, JGR, 2002; Ponce et al., EOS, 2003; Simpson et al., EOS, 2003). These near-vertical planes are well-defined below 5 km depth, in contrast to a complex pattern of surface fault traces with no through-going, connecting structure. The data suggest that, for at least some fault stopovers, the earthquake rupture surface at depth may be far simpler and more continuous than surface fault traces suggest and that fault stepovers and bends mapped at the surface do not necessarily represent segment boundaries or major energy barriers to rupture at depth. These observations raise intriguing questions about how, absent microseismisty, to determine if a fault stepover may have a simple connection at depth and what parameters, e.g. step size, total displacement, rock type, relative fault strength, etc. might control the depth variation in structural style

  2. Fault detection and diagnosis of photovoltaic systems

    NASA Astrophysics Data System (ADS)

    Wu, Xing

    The rapid growth of the solar industry over the past several years has expanded the significance of photovoltaic (PV) systems. One of the primary aims of research in building-integrated PV systems is to improve the performance of the system's efficiency, availability, and reliability. Although much work has been done on technological design to increase a photovoltaic module's efficiency, there is little research so far on fault diagnosis for PV systems. Faults in a PV system, if not detected, may not only reduce power generation, but also threaten the availability and reliability, effectively the "security" of the whole system. In this paper, first a circuit-based simulation baseline model of a PV system with maximum power point tracking (MPPT) is developed using MATLAB software. MATLAB is one of the most popular tools for integrating computation, visualization and programming in an easy-to-use modeling environment. Second, data collection of a PV system at variable surface temperatures and insolation levels under normal operation is acquired. The developed simulation model of PV system is then calibrated and improved by comparing modeled I-V and P-V characteristics with measured I--V and P--V characteristics to make sure the simulated curves are close to those measured values from the experiments. Finally, based on the circuit-based simulation model, a PV model of various types of faults will be developed by changing conditions or inputs in the MATLAB model, and the I--V and P--V characteristic curves, and the time-dependent voltage and current characteristics of the fault modalities will be characterized for each type of fault. These will be developed as benchmark I-V or P-V, or prototype transient curves. If a fault occurs in a PV system, polling and comparing actual measured I--V and P--V characteristic curves with both normal operational curves and these baseline fault curves will aid in fault diagnosis.

  3. The influence of indoor microclimate on thermal comfort and conservation of artworks: the case study of the cathedral of Matera (South Italy)

    NASA Astrophysics Data System (ADS)

    Cardinale, Tiziana; Rospi, Gianluca; Cardinale, Nicola; Paterino, Lucia; Persia, Ivan

    2014-05-01

    The Matera Cathedral was built in Apulian-Romanesque style in the thirteenth century on the highest spur of the "Civita" that divides "Sassi" district in two parts. The constructive material is the calcareous stone of the Vaglia, extracted from quarries in the area of Matera. The interior is Baroque and presents several artworks, including: mortars covered with a golden patina, a wooden ceiling, painted canvas and painting frescoes, three minor altars and a major altar of precious white marble, a nativity scene made of local painted limestone. The research had to evaluate the indoor microclimate during and after the restoration works, that also concern the installation of floor heating system to heat the indoor environments. Specifically, we have analyzed the thermal comfort and the effect that the artwork and construction materials inside the Cathedral of Matera have undergone. This evaluation was carried out in two different phases: in the first one we have investigated the state of the art (history of the site, constructive typology and artworks); in the second one we have done a systematic diagnosis and an instrumental one. The analysis were carried out in a qualitative and quantitative way and have allowed us to test indoor microclimatic parameters (air temperature, relative humidity and indoor air velocity), surface temperatures of the envelope and also Fanger's comfort indices (PMV and PPD) according to the UNI EN ISO 7730. The thermal mapping of the wall surface and of the artworks, carried out through thermal imaging camera, and the instrumental measurement campaigns were made both before restoration and after installation of the heating system; in addition measurements were taken with system on and off. The analysis thus made possible to verify that the thermo-hygrometric parameters found, as a result of the recovery operations, meet the limits indicated by the regulations and international studies. In this way, we can affirm that the indoor environment of the Cathedral of Matera is suitable both from the point of view of indoor comfort (both during the summer and the winter season) and of microclimatic parameters that are in the intervals prescribed by the regulations on the conservation of artworks of art (Ministerial Decree of 10/05/2001 dictated by the Ministry for heritage and cultural activities). Moreover the energy performance of the building-plant system was evaluated according to the Italian Norm UNI TS 11300. In particular the summer comfort is guaranteed by the huge thermal inertia of the structure that reduces the internal temperature fluctuation. Instead, the winter comfort is guaranteed by the floor heating system, which through the use of evolving fluid at low temperatures, also ensures higher efficiency and significant energy savings, as well as the protection and conservation of the artistic heritage present in the Cathedral.

  4. The Maradi fault zone: 3-D imagery of a classic wrench fault in Oman

    SciTech Connect

    Neuhaus, D. )

    1993-09-01

    The Maradi fault zone extends for almost 350 km in a north-northwest-south-southeast direction from the Oman Mountain foothills into the Arabian Sea, thereby dissecting two prolific hydrocarbon provinces, the Ghaba and Fahud salt basins. During its major Late Cretaceous period of movement, the Maradi fault zone acted as a left-lateral wrench fault. An early exploration campaign based on two-dimensional seismic targeted at fractured Cretaceous carbonates had mixed success and resulted in the discovery of one producing oil field. The structural complexity, rapidly varying carbonate facies, and uncertain fracture distribution prevented further drilling activity. In 1990 a three-dimensional (3-D) seismic survey covering some 500 km[sup 2] was acquired over the transpressional northern part of the Maradi fault zone. The good data quality and the focusing power of 3-D has enabled stunning insight into the complex structural style of a [open quotes]textbook[close quotes] wrench fault, even at deeper levels and below reverse faults hitherto unexplored. Subtle thickness changes within the carbonate reservoir and the unconformably overlying shale seal provided the tool for the identification of possible shoals and depocenters. Horizon attribute maps revealed in detail the various structural components of the wrench assemblage and highlighted areas of increased small-scale faulting/fracturing. The results of four recent exploration wells will be demonstrated and their impact on the interpretation discussed.

  5. Hydrogeological properties of fault zones in a karstified carbonate aquifer (Northern Calcareous Alps, Austria)

    NASA Astrophysics Data System (ADS)

    Bauer, H.; Schröckenfuchs, T. C.; Decker, K.

    2016-03-01

    This study presents a comparative, field-based hydrogeological characterization of exhumed, inactive fault zones in low-porosity Triassic dolostones and limestones of the Hochschwab massif, a carbonate unit of high economic importance supplying 60 % of the drinking water of Austria's capital, Vienna. Cataclastic rocks and sheared, strongly cemented breccias form low-permeability (<1 mD) domains along faults. Fractured rocks with fracture densities varying by a factor of 10 and fracture porosities varying by a factor of 3, and dilation breccias with average porosities >3 % and permeabilities >1,000 mD form high-permeability domains. With respect to fault-zone architecture and rock content, which is demonstrated to be different for dolostone and limestone, four types of faults are presented. Faults with single-stranded minor fault cores, faults with single-stranded permeable fault cores, and faults with multiple-stranded fault cores are seen as conduits. Faults with single-stranded impermeable fault cores are seen as conduit-barrier systems. Karstic carbonate dissolution occurs along fault cores in limestones and, to a lesser degree, dolostones and creates superposed high-permeability conduits. On a regional scale, faults of a particular deformation event have to be viewed as forming a network of flow conduits directing recharge more or less rapidly towards the water table and the springs. Sections of impermeable fault cores only very locally have the potential to create barriers.

  6. Denali Fault: Gillette Pass

    View north of Denali fault trace at Gillette Pass. this view shows that the surface rupture reoccupies the previous fault scarp. Also the right-lateral offset of these stream gullies has developed since deglaciation in the last 10,000 years or so....

  7. Denali Fault: Gillette Pass

    View northward of mountain near Gillette Pass showing sackung features. Here the mountaintop moved downward like a keystone, producing an uphill-facing scarp. The main Denali fault trace is on the far side of the mountain and a small splay fault is out of view below the photo....

  8. Denali Fault: Alaska Pipeline

    View south along the Trans Alaska Pipeline in the zone where it was engineered for the Denali fault. The fault trace passes beneath the pipeline between the 2nd and 3rd slider supports at the far end of the zone. A large arc in the pipe can be seen in the pipe on the right, due to shortening of the ...

  9. Denali Fault: Susitna Glacier

    Helicopters and satellite phones were integral to the geologic field response. Here, Peter Haeussler is calling a seismologist to pass along the discovery of the Susitna Glacier thrust fault. View is to the north up the Susitna Glacier. The Denali fault trace lies in the background where the two lan...

  10. Solar system fault detection

    DOEpatents

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

    1984-05-14

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

  11. Solar system fault detection

    DOEpatents

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

    1986-01-01

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

  12. High and Low Temperature Oceanic Detachment Faults

    NASA Astrophysics Data System (ADS)

    Titarenko, Sofya; McCaig, Andrew

    2013-04-01

    One of the most important discoveries in Plate Tectonics in the last ten years is a "detachment mode" of seafloor spreading. Up to 50% of the Atlantic seafloor has formed by a combination of magmatism and slip on long-lived, convex-up detachment faults, forming oceanic core complexes (OCC). Two end-member types of OCC can be defined: The Atlantis Bank on the Southwest Indian Ridge is a high temperature OCC sampled by ODP Hole 735b. Deformation was dominated by crystal-plastic flow both above and below the solidus at 800-950 °C, over a period of around 200 ka. In contrast, the Atlantis Massif at 30 °N in the Atlantic, sampled by IODP Hole 1309D, is a low temperature OCC in which crystal plastic deformation of gabbro is very rare and greenschist facies deformation was localised onto talc-tremolite-chlorite schists in serpentinite, and breccia zones in gabbro and diabase. The upper 100m of Hole 1309D contains about 43% diabase intruded into hydrated fault breccias. This detachment fault zone can be interpreted as a dyke-gabbro transition, which was originally (before flexural unroofing) a lateral boundary between active hydrothermal circulation in the fault zone and hangingwall, and intrusion of gabbroic magma in the footwall. Thus a major difference between high and low temperature detachment faults may be cooling of the latter by active hydrothermal circulation. 2-D thermal modelling suggests that if a detachment fault is formed in a magmatically robust segment of a slow spreading ridge, high temperature mylonites can be formed for 1-2 ka provided there is no significant hydrothermal cooling of the fault zone. In contrast, if the fault zone is held at temperatures of 400 °C by fluid circulation, cooling of the upper 1 km of the fault footwall occurs far too rapidly for extensive mylonites to form. Our models are consistent with published cooling rate data from geospeedometry and isotopic closure temperatures. The control on this process is likely a combination of geometry and timing of deformation; if the fault zone forms within a large semi-molten gabbro body it will be isolated from hydrothermal fluid, whereas if a series of small melt bodies collect in the footwall of a permeable detachment fault, they will cool rapidly. A corollary of our model is that at slow spreading ridges the depth of melt lenses and hence the dyke gabbro transition is determined not by spreading rate (as has been suggested at fast spreading ridges) but by the effective depth of high permeability and hence hydrothermal circulation. In actively faulting environments permeability can exist to greater depths, and magma can only easily rise above these depths as dykes or volcanics. The type of detachment fault formed may depend on whether detachment faults nucleate in a robust magmatic system where they can root into a melt zone, or if magma collects in the footwall of an active fault.

  13. Friction experiments on Alpine Fault DFDP core samples: Implications for slip style on plate boundary faults

    NASA Astrophysics Data System (ADS)

    Ikari, M.; Trütner, S.; Toy, V. G.; Carpenter, B. M.; Kopf, A.

    2014-12-01

    The Alpine Fault is a major plate-boundary fault zone that poses a significant seismic hazard in southern New Zealand, with the next major earthquake expected to be imminent. Core samples from the Alpine Fault were recovered from two Deep Fault Drilling Project pilot boreholes that penetrated the principal slip zone (PSZ). We show here that at room temperature and low effective stress (30 MPa), materials from within and very near the PSZ are weaker than the surrounding cataclasites (μ = 0.45), exhibit velocity-strengthening friction, and also tend to restrengthen (heal) rapidly. Under conditions appropriate for several kilometers depth on the Alpine Fault (100 MPa, 160 °C, fluid-saturated), a cataclasite/gouge sample located very near to the PSZ exhibits μ = 0.67, which is high compared to measurements performed at lower pressures and temperatures for the Alpine Fault and other major fault zones sampled by scientific drilling. Every major lithological unit tested under elevated P-T conditions exhibits both positive and negative values of friction velocity-dependence suggesting that they are all capable of earthquake nucleation. Using representative values of the friction velocity-dependent parameter a-b, the critical slip distance Dc, and previously documented elastic properties of the wall rock, estimated critical nucleation patch lengths may be as low as ~3 m. This small value is consistent with a seismic moment Mo = ~4x1010 or a Mw = ~1, which suggests that events of this size or larger are expected to occur as normal earthquakes and that slow or transient slip events are unlikely in the approximate depth range of 3-7 km. In conjunction with previous geodetic and seismologic observations, our results indicate that the Alpine Fault has a high potential for frictional instability throughout the brittle crust, in contrast with other major fault zones on which the uppermost portion is relatively stable.

  14. Simulation and analysis of machinery fault signals

    NASA Astrophysics Data System (ADS)

    White, M. F.

    1984-03-01

    Machinery condition monitoring is rapidly finding applications in all branches of industry. In particular, vibration monitoring is playing an increasingly important role as a tool for assisting with predictive and preventive maintenance and for improving operation efficiency of plant. Condition monitoring systems are used for the detection of incipient failure and the diagnosis of the nature of faults in operating machinery. However, for these systems to be reliable an improved understanding is required of the vibration signatures produced by machinery failure mechanisms and of methods for the interpretation of these signals. Many types of fault produce vibration signals which are impulsive in nature and which may be buried in background noise. A method is described for simulating this type of signal and modelling the various stages of incipient failure. Statistical and spectral analysis are used to describe the fault development. The influence of machinery frequency response characteristics on signal transmission from the damaged are to the measurement point are also considered.

  15. West Coast Tsunami: Cascadia's Fault?

    NASA Astrophysics Data System (ADS)

    Wei, Y.; Bernard, E. N.; Titov, V.

    2013-12-01

    The tragedies of 2004 Sumatra and 2011 Japan tsunamis exposed the limits of our knowledge in preparing for devastating tsunamis. The 1,100-km coastline of the Pacific coast of North America has tectonic and geological settings similar to Sumatra and Japan. The geological records unambiguously show that the Cascadia fault had caused devastating tsunamis in the past and this geological process will cause tsunamis in the future. Hypotheses of the rupture process of Cascadia fault include a long rupture (M9.1) along the entire fault line, short ruptures (M8.8 - M9.1) nucleating only a segment of the coastline, or a series of lesser events of M8+. Recent studies also indicate an increasing probability of small rupture occurring at the south end of the Cascadia fault. Some of these hypotheses were implemented in the development of tsunami evacuation maps in Washington and Oregon. However, the developed maps do not reflect the tsunami impact caused by the most recent updates regarding the Cascadia fault rupture process. The most recent study by Wang et al. (2013) suggests a rupture pattern of high- slip patches separated by low-slip areas constrained by estimates of coseismic subsidence based on microfossil analyses. Since this study infers that a Tokohu-type of earthquake could strike in the Cascadia subduction zone, how would such an tsunami affect the tsunami hazard assessment and planning along the Pacific Coast of North America? The rapid development of computing technology allowed us to look into the tsunami impact caused by above hypotheses using high-resolution models with large coverage of Pacific Northwest. With the slab model of MaCrory et al. (2012) (as part of the USGS slab 1.0 model) for the Cascadia earthquake, we tested the above hypotheses to assess the tsunami hazards along the entire U.S. West Coast. The modeled results indicate these hypothetical scenarios may cause runup heights very similar to those observed along Japan's coastline during the 2011 Japan tsunami,. Comparing to a long rupture, the Tohoku-type rupture may cause more serious impact at the adjacent coastline, independent of where it would occur in the Cascadia subduction zone. These findings imply that the Cascadia tsunami hazard may be greater than originally thought.

  16. The Kunlun Fault

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The Kunlun fault is one of the gigantic strike-slip faults that bound the north side of Tibet. Left-lateral motion along the 1,500-kilometer (932-mile) length of the Kunlun has occurred uniformly for the last 40,000 years at a rate of 1.1 centimeter per year, creating a cumulative offset of more than 400 meters. In this image, two splays of the fault are clearly seen crossing from east to west. The northern fault juxtaposes sedimentary rocks of the mountains against alluvial fans. Its trace is also marked by lines of vegetation, which appear red in the image. The southern, younger fault cuts through the alluvium. A dark linear area in the center of the image is wet ground where groundwater has ponded against the fault. Measurements from the image of displacements of young streams that cross the fault show 15 to 75 meters (16 to 82 yards) of left-lateral offset. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) acquired the visible light and near infrared scene on July 20, 2000. Image courtesy NASA/GSFC/MITI/ERSDAC/JAROS, and the U.S./Japan ASTER Science Team

  17. Fault detection and isolation

    NASA Technical Reports Server (NTRS)

    Bernath, Greg

    1994-01-01

    In order for a current satellite-based navigation system (such as the Global Positioning System, GPS) to meet integrity requirements, there must be a way of detecting erroneous measurements, without help from outside the system. This process is called Fault Detection and Isolation (FDI). Fault detection requires at least one redundant measurement, and can be done with a parity space algorithm. The best way around the fault isolation problem is not necessarily isolating the bad measurement, but finding a new combination of measurements which excludes it.

  18. Measuring fault tolerance with the FTAPE fault injection tool

    NASA Technical Reports Server (NTRS)

    Tsai, Timothy K.; Iyer, Ravishankar K.

    1995-01-01

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

  19. Fault weakening and earthquake instability by powder lubrication.

    PubMed

    Reches, Ze'ev; Lockner, David A

    2010-09-23

    Earthquake instability has long been attributed to fault weakening during accelerated slip, and a central question of earthquake physics is identifying the mechanisms that control this weakening. Even with much experimental effort, the weakening mechanisms have remained enigmatic. Here we present evidence for dynamic weakening of experimental faults that are sheared at velocities approaching earthquake slip rates. The experimental faults, which were made of room-dry, solid granite blocks, quickly wore to form a fine-grain rock powder known as gouge. At modest slip velocities of 10-60 mm s(-1), this newly formed gouge organized itself into a thin deforming layer that reduced the fault's strength by a factor of 2-3. After slip, the gouge rapidly 'aged' and the fault regained its strength in a matter of hours to days. Therefore, only newly formed gouge can weaken the experimental faults. Dynamic gouge formation is expected to be a common and effective mechanism of earthquake instability in the brittle crust as (1) gouge always forms during fault slip; (2) fault-gouge behaves similarly to industrial powder lubricants; (3) dynamic gouge formation explains various significant earthquake properties; and (4) gouge lubricant can form for a wide range of fault configurations, compositions and temperatures. PMID:20865001

  20. Fault weakening and earthquake instability by powder lubrication

    USGS Publications Warehouse

    Reches, Z.; Lockner, D.A.

    2010-01-01

    Earthquake instability has long been attributed to fault weakening during accelerated slip1, and a central question of earthquake physics is identifying the mechanisms that control this weakening2. Even with much experimental effort2-12, the weakening mechanisms have remained enigmatic. Here we present evidence for dynamic weakening of experimental faults that are sheared at velocities approaching earthquake slip rates. The experimental faults, which were made of room-dry, solid granite blocks, quickly wore to form a fine-grain rock powder known as gouge. At modest slip velocities of 10-60mms-1, this newly formed gouge organized itself into a thin deforming layer that reduced the fault's strength by a factor of 2-3. After slip, the gouge rapidly 'aged' and the fault regained its strength in a matter of hours to days. Therefore, only newly formed gouge can weaken the experimental faults. Dynamic gouge formation is expected to be a common and effective mechanism of earthquake instability in the brittle crust as (1) gouge always forms during fault slip5,10,12-20; (2) fault-gouge behaves similarly to industrial powder lubricants21; (3) dynamic gouge formation explains various significant earthquake properties; and (4) gouge lubricant can form for a wide range of fault configurations, compositions and temperatures15. ?? 2010 Macmillan Publishers Limited. All rights reserved.

  1. Immunity-Based Aircraft Fault Detection System

    NASA Technical Reports Server (NTRS)

    Dasgupta, D.; KrishnaKumar, K.; Wong, D.; Berry, M.

    2004-01-01

    In the study reported in this paper, we have developed and applied an Artificial Immune System (AIS) algorithm for aircraft fault detection, as an extension to a previous work on intelligent flight control (IFC). Though the prior studies had established the benefits of IFC, one area of weakness that needed to be strengthened was the control dead band induced by commanding a failed surface. Since the IFC approach uses fault accommodation with no detection, the dead band, although it reduces over time due to learning, is present and causes degradation in handling qualities. If the failure can be identified, this dead band can be further A ed to ensure rapid fault accommodation and better handling qualities. The paper describes the application of an immunity-based approach that can detect a broad spectrum of known and unforeseen failures. The approach incorporates the knowledge of the normal operational behavior of the aircraft from sensory data, and probabilistically generates a set of pattern detectors that can detect any abnormalities (including faults) in the behavior pattern indicating unsafe in-flight operation. We developed a tool called MILD (Multi-level Immune Learning Detection) based on a real-valued negative selection algorithm that can generate a small number of specialized detectors (as signatures of known failure conditions) and a larger set of generalized detectors for unknown (or possible) fault conditions. Once the fault is detected and identified, an adaptive control system would use this detection information to stabilize the aircraft by utilizing available resources (control surfaces). We experimented with data sets collected under normal and various simulated failure conditions using a piloted motion-base simulation facility. The reported results are from a collection of test cases that reflect the performance of the proposed immunity-based fault detection algorithm.

  2. WFSD fault monitoring using active seismic source

    NASA Astrophysics Data System (ADS)

    Yang, W.; Ge, H.; Wang, B.; Yuan, S.; Song, L.

    2010-12-01

    The Wenchuan Fault Scientific Drilling(WFSD)is a rapid response drilling project to the great Wenchuan earthquake. It focuses on the fault structure, earthquake physical mechanism, fluid and in-situ stress, energy budget and so on. Temporal variation of stress and physical property in the fault zone is important information for understanding earthquake physics, especially when the fault is still under the post-seismic recovery or stress modification. Seismic velocity is a good indicator of the medium mechanics, stress state within the fault zone. After the great Wenchuan Ms 8.0 earthquake, May 12, 2008, we built up a fault dynamic monitoring system using active seismic source cross the WFSD fault. It consists of a 10 ton accurately controlled eccentric mass source and eight receivers to continuously monitor the seismic velocity cross the fault zone. Combining the aftershock data, we try to monitor the fault recovery and some aftershock physical process. The observatory is located at the middle of the Longmenshan range-front fault, Mianzhu, Sichuan Province. The No.3 hole of WFSD is on the survey line near the No.4 receiver. The source and receiver site were carefully treated. All instruments were well installed to ensure the system's repeatability. Seismic velocity across the fault zone was monitored with continuous observation. The recording system consists of Guralp-40T short period seismometer and RefTek-130B recorder which was continuously GPS timed up to 20us. The active source ran since June 20, 2009. It was operated routinely at night and working continuously from 21:00 to 02:00 of the next day. So far, we have gotten almost one year recording. The seismic velocity variation may be caused by changes of the fault zone medium mechanical property, fault stress, fluid, and earth tide, barometric pressure and rainfall. Deconvolution, stacking and cross-correlation analysis were used for the velocity analysis. Results show that the relationship between seismic velocity change and the aftershock events is very complicated. An earthquake of Ms 5.6 happened at 02:03 in the morning of June 30th 2009, which was very close to the observatory site. A 5 ~ 9ms of time delay, corresponding to 0.3% of relative direct S wave velocity decrease, was observed. These variations of the velocity are much more than the possible variations caused by barometric pressure, solid earth tide and instrument factors. We speculate that the velocity variations are caused by the co-seismic effects of the aftershock. Experiment shows that the accurately controlled eccentric mass source is suitable for the fault monitoring. Large numbers of stacking (a few days recording) was done in order to increase the S/N, consequently the time resolution is not high enough to analyze the refined aftershock physical process. Some new measurements(continuous GPS, corss-hole ultrasonic) are planed to be introduced. The observation data will be analyzed in details and combined with WFSD core and downhole measurements, so as to get the stress variation and fracture deformation information for WFSD fault dynamic analysis.

  3. Fault zone structure of the Wildcat fault in Berkeley, California - Field survey and fault model test -

    NASA Astrophysics Data System (ADS)

    Ueta, K.; Onishi, C. T.; Karasaki, K.; Tanaka, S.; Hamada, T.; Sasaki, T.; Ito, H.; Tsukuda, K.; Ichikawa, K.; Goto, J.; Moriya, T.

    2010-12-01

    In order to develop hydrologic characterization technology of fault zones, it is desirable to clarify the relationship between the geologic structure and hydrologic properties of fault zones. To this end, we are performing surface-based geologic and trench investigations, geophysical surveys and borehole-based hydrologic investigations along the Wildcat fault in Berkeley,California to investigate the effect of fault zone structure on regional hydrology. The present paper outlines the fault zone structure of the Wildcat fault in Berkeley on the basis of results from trench excavation surveys. The approximately 20 - 25 km long Wildcat fault is located within the Berkeley Hills and extends northwest-southeast from Richmond to Oakland, subparallel to the Hayward fault. The Wildcat fault, which is a predominantly right-lateral strike-slip fault, steps right in a releasing bend at the Berkeley Hills region. A total of five trenches have been excavated across the fault to investigate the deformation structure of the fault zone in the bedrock. Along the Wildcat fault, multiple fault surfaces are branched, bent, paralleled, forming a complicated shear zone. The shear zone is ~ 300 m in width, and the fault surfaces may be classified under the following two groups: 1) Fault surfaces offsetting middle Miocene Claremont Chert on the east against late Miocene Orinda formation and/or San Pablo Group on the west. These NNW-SSE trending fault surfaces dip 50 - 60 to the southwest. Along the fault surfaces, fault gouge of up to 1 cm wide and foliated cataclasite of up to 60 cm wide can be observed. S-C fabrics of the fault gouge and foliated cataclasite show normal right-slip shear sense. 2) Fault surfaces forming a positive flower structure in Claremont Chert. These NW-SE trending fault surfaces are sub-vertical or steeply dipping. Along the fault surfaces, fault gouge of up to 3 cm wide and foliated cataclasite of up to 200 cm wide can be observed. S-C fabrics of the fault gouge and foliated cataclasite show reverse right-slip shear sense. We are performing sandbox experiments to investigate the three-dimensional kinematic evolution of fault systems caused by oblique-slip motion. The geometry of the Wildcat fault in the Berkeley Hills region shows a strong resemblance to our sandbox experimental model. Based on these geological and experimental data, we inferred that the complicated fault systems were dominantly developed within the fault step and the tectonic regime switched from transpression to transtension during the middle to late Miocene along the Wildcat fault.

  4. Fault rupture segmentation

    NASA Astrophysics Data System (ADS)

    Cleveland, Kenneth Michael

    A critical foundation to earthquake study and hazard assessment is the understanding of controls on fault rupture, including segmentation. Key challenges to understanding fault rupture segmentation include, but are not limited to: What determines if a fault segment will rupture in a single great event or multiple moderate events? How is slip along a fault partitioned between seismic and seismic components? How does the seismicity of a fault segment evolve over time? How representative are past events for assessing future seismic hazards? In order to address the difficult questions regarding fault rupture segmentation, new methods must be developed that utilize the information available. Much of the research presented in this study focuses on the development of new methods for attacking the challenges of understanding fault rupture segmentation. Not only do these methods exploit a broader band of information within the waveform than has traditionally been used, but they also lend themselves to the inclusion of even more seismic phases providing deeper understandings. Additionally, these methods are designed to be fast and efficient with large datasets, allowing them to utilize the enormous volume of data available. Key findings from this body of work include demonstration that focus on fundamental earthquake properties on regional scales can provide general understanding of fault rupture segmentation. We present a more modern, waveform-based method that locates events using cross-correlation of the Rayleigh waves. Additionally, cross-correlation values can also be used to calculate precise earthquake magnitudes. Finally, insight regarding earthquake rupture directivity can be easily and quickly exploited using cross-correlation of surface waves.

  5. Fault lubrication during earthquakes.

    PubMed

    Di Toro, G; Han, R; Hirose, T; De Paola, N; Nielsen, S; Mizoguchi, K; Ferri, F; Cocco, M; Shimamoto, T

    2011-03-24

    The determination of rock friction at seismic slip rates (about 1 m s(-1)) is of paramount importance in earthquake mechanics, as fault friction controls the stress drop, the mechanical work and the frictional heat generated during slip. Given the difficulty in determining friction by seismological methods, elucidating constraints are derived from experimental studies. Here we review a large set of published and unpublished experiments (∼300) performed in rotary shear apparatus at slip rates of 0.1-2.6 m s(-1). The experiments indicate a significant decrease in friction (of up to one order of magnitude), which we term fault lubrication, both for cohesive (silicate-built, quartz-built and carbonate-built) rocks and non-cohesive rocks (clay-rich, anhydrite, gypsum and dolomite gouges) typical of crustal seismogenic sources. The available mechanical work and the associated temperature rise in the slipping zone trigger a number of physicochemical processes (gelification, decarbonation and dehydration reactions, melting and so on) whose products are responsible for fault lubrication. The similarity between (1) experimental and natural fault products and (2) mechanical work measures resulting from these laboratory experiments and seismological estimates suggests that it is reasonable to extrapolate experimental data to conditions typical of earthquake nucleation depths (7-15 km). It seems that faults are lubricated during earthquakes, irrespective of the fault rock composition and of the specific weakening mechanism involved. PMID:21430777

  6. Fault tolerant magnetic bearings

    SciTech Connect

    Maslen, E.H.; Sortore, C.K.; Gillies, G.T.; Williams, R.D.; Fedigan, S.J.; Aimone, R.J.

    1999-07-01

    A fault tolerant magnetic bearing system was developed and demonstrated on a large flexible-rotor test rig. The bearing system comprises a high speed, fault tolerant digital controller, three high capacity radial magnetic bearings, one thrust bearing, conventional variable reluctance position sensors, and an array of commercial switching amplifiers. Controller fault tolerance is achieved through a very high speed voting mechanism which implements triple modular redundancy with a powered spare CPU, thereby permitting failure of up to three CPU modules without system failure. Amplifier/cabling/coil fault tolerance is achieved by using a separate power amplifier for each bearing coil and permitting amplifier reconfiguration by the controller upon detection of faults. This allows hot replacement of failed amplifiers without any system degradation and without providing any excess amplifier kVA capacity over the nominal system requirement. Implemented on a large (2440 mm in length) flexible rotor, the system shows excellent rejection of faults including the failure of three CPUs as well as failure of two adjacent amplifiers (or cabling) controlling an entire stator quadrant.

  7. 3D seismic analysis of the structure and evolution of a salt-influenced normal fault zone: A test of competing fault growth models

    NASA Astrophysics Data System (ADS)

    Jackson, Christopher A.-L.; Rotevatn, Atle

    2013-09-01

    In this paper we determine the structure and evolution of a normal fault system by applying qualitative and quantitative fault analysis techniques to a 3D seismic reflection dataset from the Suez Rift, Egypt. Our analysis indicates that the October Fault Zone is composed of two fault systems that are locally decoupled across a salt-bearing interval of Late Miocene (Messinian) age. The sub-salt system offsets pre-rift crystalline basement, and was active during the Late Oligocene-early Middle Miocene. It is composed of four, planar, NW-SE-striking segments that are hard- linked by N-S-striking segments, and up to 2 km of displacement occurs at top basement, suggesting that this fault system nucleated at or, more likely, below this structural level. The supra-salt system was active during the Pliocene-Holocene, and is composed of four, NW-SE-striking, listric fault segments, which are soft-linked by unbreached relay zones. Segments in the supra-salt fault system nucleated within Pliocene strata and have maximum throws of up to 482 m. Locally, the segments of the supra-salt fault system breach the Messinian salt to hard-link downwards with the underlying, sub-salt fault system, thus forming the upper part of a fault zone composed of: (i) a single, amalgamated fault system below the salt and (ii) a fault system composed of multiple soft-linked segments above the salt. Analysis of throw-distance (T-x) and throw-depth (T-z) plots for the supra-salt fault system, isopach maps of the associated growth strata and backstripping of intervening relay zones indicates that these faults rapidly established their lengths during the early stages of their slip history. The fault tips were then effectively ‘pinned’ and the faults accumulated displacement via predominantly downward propagation. We interpret that the October Fault Zone had the following evolutionary trend; (i) growth of the sub-salt fault system during the Oligocene-to-early Middle Miocene; (ii) cessation of activity on the sub-salt fault system during the Middle Miocene-to-?Early Pliocene; (iii) stretching of the sub- and supra-salt intervals during Pliocene regional extension, which resulted in mild reactivation of the sub-salt fault system and nucleation of the segmented supra-salt fault system, which at this time was geometrically decoupled from the sub-salt fault system; and (iv) Pliocene-to-Holocene growth of the supra-salt fault system by downwards vertical tip line propagation, which resulted in downward breaching of the salt and dip-linkage with the sub-salt fault system. The structure of the October Fault Zone and the rapid establishment of supra-salt fault lengths are compatible with the predictions of the coherent fault model, although we note that individual segments in the supra-salt array grew in accordance with the isolated fault model. Our study thereby indicates that both coherent and isolated fault models may be applicable to the growth of kilometre-scale, basin-bounding faults. Furthermore, we highlight the role that fault reactivation and dip-linkage in mechanically layered sequences can play in controlling the three-dimensional geometry of normal faults.

  8. Fault Roughness Records Strength

    NASA Astrophysics Data System (ADS)

    Brodsky, E. E.; Candela, T.; Kirkpatrick, J. D.

    2014-12-01

    Fault roughness is commonly ~0.1-1% at the outcrop exposure scale. More mature faults are smoother than less mature ones, but the overall range of roughness is surprisingly limited which suggests dynamic control. In addition, the power spectra of many exposed fault surfaces follow a single power law over scales from millimeters to 10's of meters. This is another surprising observation as distinct structures such as slickenlines and mullions are clearly visible on the same surfaces at well-defined scales. We can reconcile both observations by suggesting that the roughness of fault surfaces is controlled by the maximum strain that can be supported elastically in the wallrock. If the fault surface topography requires more than 0.1-1% strain, it fails. Invoking wallrock strength explains two additional observations on the Corona Heights fault for which we have extensive roughness data. Firstly, the surface is isotropic below a scale of 30 microns and has grooves at larger scales. Samples from at least three other faults (Dixie Valley, Mount St. Helens and San Andreas) also are isotropic at scales below 10's of microns. If grooves can only persist when the walls of the grooves have a sufficiently low slope to maintain the shape, this scale of isotropy can be predicted based on the measured slip perpendicular roughness data. The observed 30 micron scale at Corona Heights is consistent with an elastic strain of 0.01 estimated from the observed slip perpendicular roughness with a Hurst exponent of 0.8. The second observation at Corona Heights is that slickenlines are not deflected around meter-scale mullions. Yielding of these mullions at centimeter to meter scale is predicted from the slip parallel roughness as measured here. The success of the strain criterion for Corona Heights supports it as the appropriate control on fault roughness. Micromechanically, the criterion implies that failure of the fault surface is a continual process during slip. Macroscopically, the fundamental nature of the control means that 0.1 to 1% roughness should be ubiquitous on faults and can generally be used for simulating ground motion. An important caveat is that the scale-dependence of strength may result in a difference in the yield criterion at large-scales. The commonly observed values of the Hurst exponent below 1 may capture this scale-dependence.

  9. Thyristor controlled ground fault current limiting system for ungrounded power distribution systems

    SciTech Connect

    Sugimoto, S.; Neo, S.; Arita, H.; Kida, J.; Matsui, Y.; Yamagiwa, T.

    1996-04-01

    A thyristor controlled ground fault current limiting system (TGCL) was proposed to prevent one-line ground fault current rises due to increased capacitance to ground. Basic components of the TGCL are a main ground fault current limiter, which rapidly adjusts a compensating reactor level for the capacitance to ground, and the TGCL`s controller. Control is ensured by an in-phase control method for zero-phase sequence voltage and current. The method determines the direction of ground faults and the compensating reactor level. The fast control which can be realized shows the TGCL is a valuable protecting system for high ground fault current distribution systems.

  10. Rapid acceleration leads to rapid weakening in earthquake-like laboratory experiments

    USGS Publications Warehouse

    Chang, Jefferson C.; Lockner, David A.; Reches, Z.

    2012-01-01

    After nucleation, a large earthquake propagates as an expanding rupture front along a fault. This front activates countless fault patches that slip by consuming energy stored in Earth’s crust. We simulated the slip of a fault patch by rapidly loading an experimental fault with energy stored in a spinning flywheel. The spontaneous evolution of strength, acceleration, and velocity indicates that our experiments are proxies of fault-patch behavior during earthquakes of moment magnitude (Mw) = 4 to 8. We show that seismically determined earthquake parameters (e.g., displacement, velocity, magnitude, or fracture energy) can be used to estimate the intensity of the energy release during an earthquake. Our experiments further indicate that high acceleration imposed by the earthquake’s rupture front quickens dynamic weakening by intense wear of the fault zone.

  11. Rapid acceleration leads to rapid weakening in earthquake-like laboratory experiments.

    PubMed

    Chang, J C; Lockner, D A; Reches, Z

    2012-10-01

    After nucleation, a large earthquake propagates as an expanding rupture front along a fault. This front activates countless fault patches that slip by consuming energy stored in Earth's crust. We simulated the slip of a fault patch by rapidly loading an experimental fault with energy stored in a spinning flywheel. The spontaneous evolution of strength, acceleration, and velocity indicates that our experiments are proxies of fault-patch behavior during earthquakes of moment magnitude (M(w)) = 4 to 8. We show that seismically determined earthquake parameters (e.g., displacement, velocity, magnitude, or fracture energy) can be used to estimate the intensity of the energy release during an earthquake. Our experiments further indicate that high acceleration imposed by the earthquake's rupture front quickens dynamic weakening by intense wear of the fault zone. PMID:23042892

  12. Diagnosable systems for intermittent faults

    NASA Technical Reports Server (NTRS)

    Mallela, S.; Masson, G. M.

    1978-01-01

    The fault diagnosis capabilities of systems composed of interconnected units capable of testing each other are studied for the case of systems with intermittent faults. A central role is played by the concept of t(i)-fault diagnosability. A system is said to be t(i)-fault diagnosable when it is such that if no more than t(i) units are intermittently faulty then a fault-free unit will never be diagnosed as faulty and the diagnosis at any time is at worst incomplete. Necessary and sufficient conditions for t(i)-fault diagnosability are proved, and bounds for t(i) are established. The conditions are in general more restrictive than those for permanent-fault diagnosability. For intermittent faults there is only one testing strategy (repetitive testing), and consequently only one type of intermittent-fault diagnosable system.

  13. Bearing Fault Diagnosis Based on Statistical Locally Linear Embedding

    PubMed Central

    Wang, Xiang; Zheng, Yuan; Zhao, Zhenzhou; Wang, Jinping

    2015-01-01

    Fault diagnosis is essentially a kind of pattern recognition. The measured signal samples usually distribute on nonlinear low-dimensional manifolds embedded in the high-dimensional signal space, so how to implement feature extraction, dimensionality reduction and improve recognition performance is a crucial task. In this paper a novel machinery fault diagnosis approach based on a statistical locally linear embedding (S-LLE) algorithm which is an extension of LLE by exploiting the fault class label information is proposed. The fault diagnosis approach first extracts the intrinsic manifold features from the high-dimensional feature vectors which are obtained from vibration signals that feature extraction by time-domain, frequency-domain and empirical mode decomposition (EMD), and then translates the complex mode space into a salient low-dimensional feature space by the manifold learning algorithm S-LLE, which outperforms other feature reduction methods such as PCA, LDA and LLE. Finally in the feature reduction space pattern classification and fault diagnosis by classifier are carried out easily and rapidly. Rolling bearing fault signals are used to validate the proposed fault diagnosis approach. The results indicate that the proposed approach obviously improves the classification performance of fault pattern recognition and outperforms the other traditional approaches. PMID:26153771

  14. Bearing Fault Diagnosis Based on Statistical Locally Linear Embedding.

    PubMed

    Wang, Xiang; Zheng, Yuan; Zhao, Zhenzhou; Wang, Jinping

    2015-01-01

    Fault diagnosis is essentially a kind of pattern recognition. The measured signal samples usually distribute on nonlinear low-dimensional manifolds embedded in the high-dimensional signal space, so how to implement feature extraction, dimensionality reduction and improve recognition performance is a crucial task. In this paper a novel machinery fault diagnosis approach based on a statistical locally linear embedding (S-LLE) algorithm which is an extension of LLE by exploiting the fault class label information is proposed. The fault diagnosis approach first extracts the intrinsic manifold features from the high-dimensional feature vectors which are obtained from vibration signals that feature extraction by time-domain, frequency-domain and empirical mode decomposition (EMD), and then translates the complex mode space into a salient low-dimensional feature space by the manifold learning algorithm S-LLE, which outperforms other feature reduction methods such as PCA, LDA and LLE. Finally in the feature reduction space pattern classification and fault diagnosis by classifier are carried out easily and rapidly. Rolling bearing fault signals are used to validate the proposed fault diagnosis approach. The results indicate that the proposed approach obviously improves the classification performance of fault pattern recognition and outperforms the other traditional approaches. PMID:26153771

  15. Effects of fault propagation on superficial soils/gravel aquifer properties: The Chihshang Fault in Eastern Taiwan

    NASA Astrophysics Data System (ADS)

    Mu, C.; Lee, J.; guglielmi, Y.

    2013-12-01

    A mature bedrock fault zone generally consists of a fault core, a damage zone, and a surrounding host rock with different permeabilities, which mainly depend on the fracture density. However, near the surface, when an active thrust fault propagates from bedrocks into an unconsolidated surface cover, it results in a diffused fault zone, which may influence the hydraulic and mechanical properties around the fault zone. It is thus of great concern to understand to which extent surface soil/gravel hydraulic properties modifications by continuously active faulting can impact geotechnical projects in countries under active tectonic context, such as Taiwan, where active faults often are blinded beneath thick soil/gravel covers. By contrast, it is also interesting to decipher those fault-induced permeability modifications to estimate potential activity precursors to large earthquakes. Here, we combined a variety of measurements and analyses on the Chihshang fault, located at the plate suture between the Philippine Sea and Eurasian plates, which converge at a rapid rate of 8 cm/yr in Taiwan. At the Chinyuan site, the Chihshang fault is propagating from depth to emerge through thick alluvial deposits. We characterized the fault geometry and slip behavior at the shallow level by measuring and analyzing horizontal, vertical displacements, and groundwater table across the surface fault zone. The yielded fault dip of 45o in the shallow alluvium is consistent with the observations from surface ruptures and subsurface core logging. The 7-year-long groundwater table record shows that the piezometric level in the hanging wall is about 8 meter higher than that in the footwall in the summer; and about 10 meter higher in the winter. Repeated slug tests have been monthly conducted since 2007 to provide the average permeability within the fault zone and the presumably low-deformed zone outside of the diffused fault zone. Based on in-situ measurements at four wells across the fault zone, a 2-D modeling of pore pressure distribution around the fault zone is conducted using the finite-difference method (FLAC3D). The results showed that the permeability within the fault zone is 10-10 cm2 and outside of the fault zone is 10-8 cm2. The low permeable zone is estimated to be about 4-5 meters thick, and its location matches with the main fault structures mapped from geological and geodetic results. This low permeability fault zone acts as a hydraulic boundary, which explains the difference in the piezometric levels observed within the soil aquifer across the fault zone. This study provides a good natural analogue to permeability changes induced by clay smearing during soft sediments faulting. It also shows the significant impact of active thrust faults on soft sediments aquifer drainage.

  16. Validated Fault Tolerant Architectures for Space Station

    NASA Technical Reports Server (NTRS)

    Lala, Jaynarayan H.

    1990-01-01

    Viewgraphs on validated fault tolerant architectures for space station are presented. Topics covered include: fault tolerance approach; advanced information processing system (AIPS); and fault tolerant parallel processor (FTPP).

  17. Novel methodology for the extraction and identification of natural dyestuffs in historical textiles by HPLC-UV-Vis-ESI MS. Case study: chasubles from the Wawel Cathedral collection.

    PubMed

    Lech, Katarzyna; Jarosz, Maciej

    2011-03-01

    High-performance liquid chromatography coupled with spectrophotometric and electrospray mass spectrometric detection (HPLC-UV-Vis-ESI MS) was used for characterization of natural dyes present in historical art works. The gradient program was developed for identification of 29 colorants of various polarities. Dual detection system (UV-Vis and ESI MS) allowed differentiation of all compounds, even if they were not completely separated. This enabled examination of more color compounds over a substantially shorter time in comparison with previously recommended methods. Moreover, for extraction of colorants from historical textiles a two-step sequential procedure was proposed, excluding evaporation used in earlier procedures. The developed method was successfully applied to identification of indigotin, carminic, kermesic, flavokermesic, dcII, dcIV, dcVII, and ellagic acids as well as luteolin, apigenin, and genistein in red, violet, and green fibers taken from three selected historical chasubles which belong to the collection of the Wawel Cathedral treasury (Cracow, Poland). Italian textiles from the fifteenth and sixteenth centuries, of which chasubles were made, were dyed with a limited number of dyestuffs, consistently used for all batches of fabrics. The obtained results also allowed confirmation of the structure of the so-called "dcII" component of cochineal as a C-glucose derivative of flavokermesic acid. PMID:21188578

  18. Long-Term Monitoring of Fresco Paintings in the Cathedral of Valencia (Spain) Through Humidity and Temperature Sensors in Various Locations for Preventive Conservation

    PubMed Central

    Zarzo, Manuel; Fernández-Navajas, Angel; García-Diego, Fernando-Juan

    2011-01-01

    We describe the performance of a microclimate monitoring system that was implemented for the preventive conservation of the Renaissance frescoes in the apse vault of the Cathedral of Valencia, that were restored in 2006. This system comprises 29 relative humidity (RH) and temperature sensors: 10 of them inserted into the plaster layer supporting the fresco paintings, 10 sensors in the walls close to the frescoes and nine sensors measuring the indoor microclimate at different points of the vault. Principal component analysis was applied to RH data recorded in 2007. The analysis was repeated with data collected in 2008 and 2010. The resulting loading plots revealed that the similarities and dissimilarities among sensors were approximately maintained along the three years. A physical interpretation was provided for the first and second principal components. Interestingly, sensors recording the highest RH values correspond to zones where humidity problems are causing formation of efflorescence. Recorded data of RH and temperature are discussed according to Italian Standard UNI 10829 (1999). PMID:22164100

  19. Insurance Applications of Active Fault Maps Showing Epistemic Uncertainty

    NASA Astrophysics Data System (ADS)

    Woo, G.

    2005-12-01

    Insurance loss modeling for earthquakes utilizes available maps of active faulting produced by geoscientists. All such maps are subject to uncertainty, arising from lack of knowledge of fault geometry and rupture history. Field work to undertake geological fault investigations drains human and monetary resources, and this inevitably limits the resolution of fault parameters. Some areas are more accessible than others; some may be of greater social or economic importance than others; some areas may be investigated more rapidly or diligently than others; or funding restrictions may have curtailed the extent of the fault mapping program. In contrast with the aleatory uncertainty associated with the inherent variability in the dynamics of earthquake fault rupture, uncertainty associated with lack of knowledge of fault geometry and rupture history is epistemic. The extent of this epistemic uncertainty may vary substantially from one regional or national fault map to another. However aware the local cartographer may be, this uncertainty is generally not conveyed in detail to the international map user. For example, an area may be left blank for a variety of reasons, ranging from lack of sufficient investigation of a fault to lack of convincing evidence of activity. Epistemic uncertainty in fault parameters is of concern in any probabilistic assessment of seismic hazard, not least in insurance earthquake risk applications. A logic-tree framework is appropriate for incorporating epistemic uncertainty. Some insurance contracts cover specific high-value properties or transport infrastructure, and therefore are extremely sensitive to the geometry of active faulting. Alternative Risk Transfer (ART) to the capital markets may also be considered. In order for such insurance or ART contracts to be properly priced, uncertainty should be taken into account. Accordingly, an estimate is needed for the likelihood of surface rupture capable of causing severe damage. Especially where a high deductible is in force, this requires estimation of the epistemic uncertainty on fault geometry and activity. Transport infrastructure insurance is of practical interest in seismic countries. On the North Anatolian Fault in Turkey, there is uncertainty over an unbroken segment between the eastern end of the Dazce Fault and Bolu. This may have ruptured during the 1944 earthquake. Existing hazard maps may simply use a question mark to flag uncertainty. However, a far more informative type of hazard map might express spatial variations in the confidence level associated with a fault map. Through such visual guidance, an insurance risk analyst would be better placed to price earthquake cover, allowing for epistemic uncertainty.

  20. Recognizing Basement Fault Reactivation in 3D Seismic Datasets

    NASA Astrophysics Data System (ADS)

    Imber, J.; McCaffrey, K.; Holdsworth, R.; England, R.; Freeman, S.; Dore, T.; Geldjvik, G.

    2003-04-01

    3D seismic data are now widely used for hydrocarbon exploration and production, and because of its ability to image sub-surface structures, the technology represents one of the most important conceptual advances in the Earth Sciences in recent years. It provides an important tool capable of addressing fundamental questions concerning the way in which fault systems evolve in the continental crust, the effects of inherited crustal weakness on rifting style and the control of fault networks on reservoir properties. Preliminary analyses of published offshore seismic data demonstrate that there are quantifiable differences in the geometric evolution and growth of "thin-skinned" normal fault systems in which there is no direct basement involvement compared to those developed above little- and highly-reactivated basement structures. Reactivated fault systems are characterised by rapid strain localisation and fault lengths that are controlled by up-dip propagation of basement structures (Walsh et al. 2002). Thus, fault growth during reactivation is likely to be achieved by increasing cumulative displacement with negligible lateral propagation. Important questions remain, however, concerning the way in which faults grow and localise displacement during the earliest stages of reactivation. In particular, we have little detailed understanding of the extent to which basement fault geometry (e.g. polarity, segmentation) influences the pattern of faulting observed in the cover sequence, the kinematics of up-dip fault propagation and/or linkage, or the degree of displacement localisation at low bulk strains. Normal faults that developed in response to glacial retreat on the NE Atlantic Margin reactivate pre-existing Mesozoic, Caledonian and/or Precambrian structures and are characterised by low displacements (throws typically 100--101 m), thus representing the earliest stages in the development of a reactivated fault system. Spectacular images of postglacial and underlying Mesozoic normal fault systems are available from high-resolution (12.5 m bin spacing) 3-D seismic, providing a unique opportunity to study the kinematics of fault reactivation. In addition to improving our understanding of early stage fault growth during reactivation, our study will shed new light on the role of basement reactivation during the development of the NE Atlantic Margin.

  1. Computer hardware fault administration

    DOEpatents

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

    2010-09-14

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

  2. Cable fault locator research

    NASA Astrophysics Data System (ADS)

    Cole, C. A.; Honey, S. K.; Petro, J. P.; Phillips, A. C.

    1982-07-01

    Cable fault location and the construction of four field test units are discussed. Swept frequency sounding of mine cables with RF signals was the technique most thoroughly investigated. The swept frequency technique is supplemented with a form of moving target indication to provide a method for locating the position of a technician along a cable and relative to a suspected fault. Separate, more limited investigations involved high voltage time domain reflectometry and acoustical probing of mine cables. Particular areas of research included microprocessor-based control of the swept frequency system, a microprocessor based fast Fourier transform for spectral analysis, and RF synthesizers.

  3. Fault tolerant linear actuator

    DOEpatents

    Tesar, Delbert

    2004-09-14

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

  4. DIFFERENTIAL FAULT SENSING CIRCUIT

    DOEpatents

    Roberts, J.H.

    1961-09-01

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

  5. Fault terminations, Seminoe Mountains, Wyoming

    SciTech Connect

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

    1992-01-01

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

  6. Fault displacement hazard for strike-slip faults

    USGS Publications Warehouse

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

    2011-01-01

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

  7. Fault tree models for fault tolerant hypercube multiprocessors

    NASA Technical Reports Server (NTRS)

    Boyd, Mark A.; Tuazon, Jezus O.

    1991-01-01

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

  8. Normal-fault development in two-phase experimental models of shortening followed by extension and comparison to natural examples

    NASA Astrophysics Data System (ADS)

    Warrell, K. F.; Withjack, M. O.; Schlische, R. W.

    2014-12-01

    Field- and seismic-reflection-based studies have documented the influence of pre-existing thrust faults on normal-fault development during subsequent extension. Published experimental (analog) models of shortening followed by extension with dry sand as the modeling medium show limited extensional reactivation of moderate-angle thrust faults (dipping > 40º). These dry sand models provide insight into the influence of pre-existing thrusts on normal-fault development, but these models have not reactivated low-angle (< 35º) thrust faults as seen in nature. New experimental (analog) models, using wet clay over silicone polymer to simulate brittle upper crust over ductile lower crust, suggest that low-angle thrust faults from an older shortening phase can reactivate as normal faults. In two-phase models of shortening followed by extension, normal faults nucleate above pre-existing thrust faults and likely link with thrusts at depth to create listric faults, movement on which produces rollover folds. Faults grow and link more rapidly in two-phase than in single-phase (extension-only) models. Fewer faults with higher displacements form in two-phase models, likely because, for a given displacement magnitude, a low-angle normal fault accommodates more horizontal extension than a high-angle normal fault. The resulting rift basins are wider and shallower than those forming along high-angle normal faults. Features in these models are similar to natural examples. Seismic-reflection profiles from the outer Hebrides, offshore Scotland, show listric faults partially reactivating pre-existing thrust faults with a rollover fold in the hanging wall; in crystalline basement, the thrust is reactivated, and in overlying sedimentary strata, a new, high-angle normal fault forms. Profiles from the Chignecto subbasin of the Fundy basin, offshore Canada, show full reactivation of thrust faults as low-angle normal faults where crystalline basement rocks make up the footwall.

  9. Fault-Tolerant Flight Computer

    NASA Technical Reports Server (NTRS)

    Chau, Savio

    1996-01-01

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

  10. Dynamic Fault Detection Chassis

    SciTech Connect

    Mize, Jeffery J

    2007-01-01

    Abstract The high frequency switching megawatt-class High Voltage Converter Modulator (HVCM) developed by Los Alamos National Laboratory for the Oak Ridge National Laboratory's Spallation Neutron Source (SNS) is now in operation. One of the major problems with the modulator systems is shoot-thru conditions that can occur in a IGBTs H-bridge topology resulting in large fault currents and device failure in a few microseconds. The Dynamic Fault Detection Chassis (DFDC) is a fault monitoring system; it monitors transformer flux saturation using a window comparator and dV/dt events on the cathode voltage caused by any abnormality such as capacitor breakdown, transformer primary turns shorts, or dielectric breakdown between the transformer primary and secondary. If faults are detected, the DFDC will inhibit the IGBT gate drives and shut the system down, significantly reducing the possibility of a shoot-thru condition or other equipment damaging events. In this paper, we will present system integration considerations, performance characteristics of the DFDC, and discuss its ability to significantly reduce costly down time for the entire facility.

  11. Row fault detection system

    DOEpatents

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

    2010-02-23

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

  12. Row fault detection system

    DOEpatents

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

    2012-02-07

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

  13. Row fault detection system

    SciTech Connect

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

    2008-10-14

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

  14. Fault-Related Sanctuaries

    NASA Astrophysics Data System (ADS)

    Piccardi, L.

    2001-12-01

    Beyond the study of historical surface faulting events, this work investigates the possibility, in specific cases, of identifying pre-historical events whose memory survives in myths and legends. The myths of many famous sacred places of the ancient world contain relevant telluric references: "sacred" earthquakes, openings to the Underworld and/or chthonic dragons. Given the strong correspondence with local geological evidence, these myths may be considered as describing natural phenomena. It has been possible in this way to shed light on the geologic origin of famous myths (Piccardi, 1999, 2000 and 2001). Interdisciplinary researches reveal that the origin of several ancient sanctuaries may be linked in particular to peculiar geological phenomena observed on local active faults (like ground shaking and coseismic surface ruptures, gas and flames emissions, strong underground rumours). In many of these sanctuaries the sacred area is laid directly above the active fault. In a few cases, faulting has affected also the archaeological relics, right through the main temple (e.g. Delphi, Cnidus, Hierapolis of Phrygia). As such, the arrangement of the cult site and content of relative myths suggest that specific points along the trace of active faults have been noticed in the past and worshiped as special `sacred' places, most likely interpreted as Hades' Doors. The mythological stratification of most of these sanctuaries dates back to prehistory, and points to a common derivation from the cult of the Mother Goddess (the Lady of the Doors), which was largely widespread since at least 25000 BC. The cult itself was later reconverted into various different divinities, while the `sacred doors' of the Great Goddess and/or the dragons (offspring of Mother Earth and generally regarded as Keepers of the Doors) persisted in more recent mythologies. Piccardi L., 1999: The "Footprints" of the Archangel: Evidence of Early-Medieval Surface Faulting at Monte Sant'Angelo (Gargano, Italy). European Union of Geophysics Congress, Strasbourg, March 1999. Piccardi L., 2000: Active faulting at Delphi (Greece): seismotectonic remarks and a hypothesis for the geological environment of a myth. Geology, 28, 651-654. Piccardi L., 2001: Seismotectonic Origin of the Monster of Loch Ness. Earth System Processes, Joint Meeting of G.S.A. and G.S.L., Edinburgh, June 2001.

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

    USGS Publications Warehouse

    Nason, R.

    1979-01-01

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

  16. An empirical comparison of software fault tolerance and fault elimination

    NASA Technical Reports Server (NTRS)

    Shimeall, Timothy J.; Leveson, Nancy G.

    1991-01-01

    Reliability is an important concern in the development of software for modern systems. Some researchers have hypothesized that particular fault-handling approaches or techniques are so effective that other approaches or techniques are superfluous. The authors have performed a study that compares two major approaches to the improvement of software, software fault elimination and software fault tolerance, by examination of the fault detection obtained by five techniques: run-time assertions, multi-version voting, functional testing augmented by structural testing, code reading by stepwise abstraction, and static data-flow analysis. This study has focused on characterizing the sets of faults detected by the techniques and on characterizing the relationships between these sets of faults. The results of the study show that none of the techniques studied is necessarily redundant to any combination of the others. Further results reveal strengths and weakness in the fault detection by the techniques studied and suggest directions for future research.

  17. Older drivers' risks of at-fault motor vehicle collisions.

    PubMed

    Ichikawa, Masao; Nakahara, Shinji; Taniguchi, Ayako

    2015-08-01

    In aging societies, increasing numbers of older drivers are involved in motor vehicle collisions (MVCs), and preserving their safety is a growing concern. In this study, we focused on whether older drivers were more likely to cause MVCs and injuries than drivers in other age groups. To do so we compared at-fault MVC incidence and resulting injury risks by drivers' ages, using data from Japan, a country with a rapidly aging population. The at-fault MVC incidence was calculated based on distance traveled made for non-commercial purposes, and the injury risks posed to at-fault drivers and other road users per at-fault MVCs. We used MVC data for 2010 from the National Police Agency of Japan and driving exposure data from the Nationwide Person Trip Survey conducted by a Japanese governmental ministry in 2010. The at-fault MVC incidence showed a U-shaped curve across the drivers' ages, where teenage and the oldest drivers appeared to be the highest risk groups in terms of causing MVCs, and the incidence was higher for female drivers after age 25. The injury risk older drivers posed to other vehicle occupants because of their at-fault MVCs was lower than for drivers in other age groups, while their own injury risk appeared much higher. As the number of older drivers is increasing, efforts to reduce their at-fault MVCs appear justified. PMID:25980917

  18. Ubiquitous weakening of faults due to thermal pressurization

    NASA Astrophysics Data System (ADS)

    Viesca, Robert C.; Garagash, Dmitry I.

    2015-11-01

    Laboratory simulations of earthquakes show that at high slip rates, faults can weaken significantly, aiding rupture. Various mechanisms, such as thermal pressurization and flash heating, have been proposed to cause this weakening during laboratory experiments, yet the processes that aid fault slip in nature remain unknown. Measurements of seismic radiation during an earthquake can be used to estimate the frictional work associated with fault weakening, known as an event's fracture energy. Here we compile new and existing measurements of fracture energy for earthquakes globally that vary in size from borehole microseismicity to great earthquakes. We observe a distinct transition in how fracture energy scales with event size, which implies that faults weaken differently during small and large earthquakes, and earthquakes are not self-similar. We use an elastodynamic numerical model of earthquake rupture to explore possible mechanisms. We find that thermal pressurization of pore fluid by the rapid shear heating of fault gouge can account for the observed scaling of fracture energy in small and large earthquakes, over seven orders of fault slip magnitude. We conclude that thermal pressurization is a widespread and prominent process for fault weakening.

  19. An analysis of the black crusts from the Seville Cathedral: a challenge to deepen the understanding of the relationships among microstructure, microchemical features and pollution sources.

    PubMed

    Ruffolo, Silvestro A; Comite, Valeria; La Russa, Mauro F; Belfiore, Cristina M; Barca, Donatella; Bonazza, Alessandra; Crisci, Gino M; Pezzino, Antonino; Sabbioni, Cristina

    2015-01-01

    The Cathedral of Seville is one of the most important buildings in the whole of southern Spain. It suffers, like most of the historical buildings located in urban environments, from several degradation phenomena related to the high pollution level. Undoubtedly, the formation of black crusts plays a crucial role in the decay of the stone materials belonging to the church. Their formation occurs mainly on carbonate building materials, whose interaction with a sulfur oxide-enriched atmosphere leads to the transformation of calcium carbonate (calcite) into calcium sulfate dihydrate (gypsum) which, together with embedded carbonaceous particles, forms the black crusts on the stone surface. To better understand the composition and the formation dynamics of this degradation product and to identify the pollutant sources and evaluate their impact on the stone material, an analytical study was carried out on the black crust samples collected from different areas of the building. For a complete characterization of the black crusts, several techniques were used, including laser ablation inductively coupled plasma mass spectrometry, Fourier transform infrared spectroscopy, micro infrared spectroscopy, optical and scanning electron microscopy. This battery of tests provided information about the nature and distribution of the mineralogical phases and the elements within the crusts and the crust-substrate interface, contributing to the identification of the major pollution sources responsible for the deterioration of the monument over time. In addition, the results revealed a relation among the height of sampling, the surface exposure and the concentration of heavy metals. Finally, information has been provided about the origin of the concentration gradients of some metals. PMID:25260161

  20. Fault Scarp Offsets and Fault Population Analysis on Dione

    NASA Astrophysics Data System (ADS)

    Tarlow, S.; Collins, G. C.

    2010-12-01

    Cassini images of Dione show several fault zones cutting through the moon’s icy surface. We have measured the displacement and length of 271 faults, and estimated the strain occurring in 6 different fault zones. These measurements allow us to quantify the total amount of surface strain on Dione as well as constrain what processes might have caused these faults to form. Though we do not have detailed topography across fault scarps on Dione, we can use their projected size on the camera plane to estimate their heights, assuming a reasonable surface slope. Starting with high resolution images of Dione obtained by the Cassini ISS, we marked points at the top to the bottom of each fault scarp to measure the fault’s projected displacement and its orientation along strike. Line and sample information for the measurements were then processed through ISIS to derive latitude/longitude information and pixel dimensions. We then calculate the three dimensional orientation of a vector running from the bottom to the top of the fault scarp, assuming a 45 degree angle with respect to the surface, and project this vector onto the spacecraft camera plane. This projected vector gives us a correction factor to estimate the actual vertical displacement of the fault scarp. This process was repeated many times for each fault, to show variations of displacement along the length of the fault. To compare each fault to its neighbors and see how strain was accommodated across a population of faults, we divided the faults into fault zones, and created new coordinate systems oriented along the central axis of each fault zone. We could then quantify the amount of fault overlap and add the displacement of overlapping faults to estimate the amount of strain accommodated in each zone. Faults in the southern portion of Padua have a strain of 0.031(+/-) 0.0097, central Padua exhibits a strain of .032(+/-) 0.012, and faults in northern Padua have a strain of 0.025(+/-) 0.0080. The western faults of Eurotas have a strain of 0.031(+/-) 0.011, while the eastern faults have a strain of 0.037(+/-) 0.025. Lastly, Clusium has a strain of 0.10 (+/-) 0.029. We also calculated the ratio of maximum fault displacement vs. the length of the faults, and we found this ratio to be 0.019 when drawing a trend line through all the faults that were analyzed. D/L measurements performed on two faults on Europa using stereo topography showed a value of .021 (Nimmo and Schenk 2006), the only other icy satellite where this ratio has been measured. In contrast, faults on Earth has a D/L ratio of about .1 and Mars has a D/L Ratio of about .01 (Schultz et al. 2006).

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

    NASA Astrophysics Data System (ADS)

    Padilla, Peter A.

    1991-03-01

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

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

    NASA Technical Reports Server (NTRS)

    Padilla, Peter A.

    1991-01-01

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

  3. Holocene faulting on the Mission fault, northwest Montana

    SciTech Connect

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

    1993-04-01

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

  4. An experiment in software fault elimination and fault tolerance

    SciTech Connect

    Shimeall, T.J.

    1989-01-01

    Three primary approaches have been taken in developing methods to improve software reliability: fault avoidance, fault elimination and fault tolerance. This study investigates the error detection obtained by application of two of these approaches, fault tolerance and fault elimination, on a set of independently developed versions of a program. Different fault detection techniques following each approach are used to provide a broad exposure of each approach on the versions. The fault detection techniques chosen were multi-version voting, programmer-inserted run-time assertions, testing, code reading of uncommented code by stepwise abstraction and static data flow analysis. Voting and run-time assertions are most commonly associated with fault tolerance. Testing, code reading and static data flow analysis are most commonly associated with fault elimination. After application of the techniques following each approach, the errors detected and the circumstances of detection were analyzed as a means of characterizing the differences between the approaches. The results of this study provide insight on a series of research questions. The results demonstrate weaknesses in the fault tolerance approach and specifically in the multi-version voting method. In particular, the results demonstrate that voting of untested software may produce an insufficient improvement in the probability of producing a correct result to consider such use in systems where reliability is important. Voting is not to be a substitute for testing. Examination of the faults detected in this experiment show that the majority of faults were detected by only one technique. The results of this study suggest a series of questions for further research. For example, research is needed on how to broaden the classes of faults detected by each technique.

  5. Randomness fault detection system

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

  6. Managing Fault Management Development

    NASA Technical Reports Server (NTRS)

    McDougal, John M.

    2010-01-01

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

  7. Displacement Gradients on the Eastern Kunlun Fault: Implications for the Kinematics of Deformation in Tibet

    NASA Astrophysics Data System (ADS)

    Harkins, N.; Kirby, E.; Burbank, D.; Wang, E.

    2003-12-01

    The question of whether large strike-slip fault systems in Asia accommodate eastward extrusion of quasi-rigid Tibetan lithosphere or whether these faults accommodate internal variations in strain between deforming regions of thickened Tibetan crust is central to a more fundamental question - do the rules of plate tectonics govern intracontinental deformation? The Kunlun fault, in north-central Tibet presents a key opportunity to evaluate competing models for the kinematics of Asian deformation. Although initial remote sensing interpretations of the eastward extent of the fault system suggested that the fault terminated within the Tibetan Plateau, recent regional maps interpret the fault to be linked with structures transecting the plateau margin. Coupled with rapid and uniform slip rate ( 1 cm/yr) along 600km of the fault (Van der Woerd, 2002), the fault is argued to accommodate eastward extrusion of much of central Tibet, Here we evaluate this hypothesis with new geomorphic mapping and observations of Holocene fluvial terraces and fault scarps along the easternmost 100km of the Kunlun fault. Our mapping suggests that significant displacement is not transmitted beyond the eastern margin of the Tibetan Plateau. Moreover, we exploit the preservation of flights of fluvial terraces as precise markers of displacement along this segment of the fault; coupled with radiocarbon ages of detrital charcoal, offsets of terrace risers at two localities yield preliminary slip rates ranging from 6 mm/yr to 2 mm/yr. Viewed in concert with previous rate determinations, slip rates appear to decrease toward the eastern end of the fault. We are currently working to assess the degree to which this displacement gradient is absorbed by shortening and crustal thickening within the Anyemaqen Shan and/or reflects distributed shear and rotation of the fault. Regardless, our preliminary results indicate that the Kunlun fault does not control extrusion of Tibetan lithosphere, but rather suggest that fault displacement is intimately tied to regional deformation gradients.

  8. Fault tolerant control laws

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

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

  9. Dynamic pulverization by rapid decompression

    NASA Astrophysics Data System (ADS)

    Mitchell, T. M.; Billi, A.; Miller, S. A.; Goldsby, D. L.; Scholz, C. H.; Gran, J. K.; Simons, J.

    2013-12-01

    In recent years several studies have identified so-called ';pulverized rocks' on various crustal-scale faults, a type of intensely damaged fault rock which has undergone minimal shear strain, and the occurrence of which has been linked to damage induced by transient stress perturbations during earthquake rupture. Several dynamic mechanisms have been proposed for the generation of pulverized rocks, such as compressive loading by high-frequency stress pulses due to the radiation of seismic waves and/or explosive dilation in tension in rocks containing pressurized pore fluids due to instantaneous reductions in fault-normal stress. Here, we demonstrate an explosive pulverization mechanism by imparting rapid drops in gas confining pressure for gas-saturated (effectively unconfined) rock samples. Using a specially designed pressure vessel allowing near-instantaneous decompression of rock samples via a large-diameter blow-out diaphragm, we show that low-permeability granitic rocks can pulverize by pore fluid-driven volumetric expansion (i.e. hydrofracture) where the confining pressure drops faster than the pore pressure of the rock. Microstructural observations show pervasive pulverization with minor shear in granitic samples, and significantly less damage in limestone and sandstones which have higher initial permeabilities. Permeability measurements on granitic samples following rapid decompression show increases of nearly 4 orders of magnitude in permeability, to values as high as 10-15 m2, and reductions in ultrasonic P-wave velocities of up to 60 %, compared to the starting samples. We propose that for ruptures that generate dynamic reductions in local stress, absolute tension is not necessarily required for pervasive damage or pulverization; rather, providing that the permeability of the fault rocks is low enough, a rapid drop in confining pressure below the pore fluid pressure by at least the tensile strength of the rock may cause pulverization. This may explain field observations suggesting that pulverized rocks surround faults cutting low-permeability crystalline rock. Pulverization by rapid decompression in seismogenic faults is likely controlled by complex interplays between rock permeability and tensile strength, pore fluid pressure and the magnitude and duration of the transient stress reduction.

  10. Symbiosis of Uas Photogrammetry and Tls for Surveying and 3d Modeling of Cultural Heritage Monuments - a Case Study about the Cathedral of ST. Nicholas in the City of Greifswald

    NASA Astrophysics Data System (ADS)

    Grenzdörffer, G. J.; Naumann, M.,; Niemeyer, F.; Frank, A.

    2015-08-01

    In this contribution the possibility to combine terrestrial laser scanner (TLS) measurements and UAS photogrammetry for the detailed description and high quality surveying of a cultural monument will be illustrated by the example of the Cathedral of St. Nicholas in the city of Greifswald. Due to the different nature of UAS photogrammetry and TLS walls and windows as well as portions of roofs are captured with a different level of completeness and accuracy. The average deviations of the test areas on the overlap between the two measurement methods ranges from 0.015 m to 0.033 m with standard deviations of 0.025 m to 0.088 m.

  11. Fault Parameters of The 1999 Izmit Earthquake Inferred From Accerelogram Near The Fault

    NASA Astrophysics Data System (ADS)

    Aochi, H.; Madariaga, R.

    We simulated the dynamic rupture process and seismic wave propagation of the 1999 Izmit, Turkey, earthquake, using a 3D boundary integral equation method (BIEM) and a finite difference method (FDM). Although we have to know a priori the initial situation (fault geometry, frictional parameters, tectonic stress, etc) for accomplishing numerical simulation, it is still difficult to decide them quantitatively and reasonably. In this work, we aim to look for a better modeling by trying different fault models and parameters and then by comparing seismograms. Especially we focus on one of the seismic stations, SKR (Sakarya), which is located just a few km apart from the fault. The record of SKR in the EW component shows briefly an envelope of the waveform in the positive (east) direction. The maximum velocity was more than 80 cm/s and its duration was several seconds. This suggest a strong rupture passage with high speed as shown in seismic inversion result (Bouchon et al., 2001). For the purpose reproducing waveform envelopes, rupture should propagate smoothly and continuously along the fault. This also infers that a fault should be rather smooth and continuous beneath the Sapanca lake, although some geological survey of fault trace infers a discrepancy at this point. Next, in order to explain large velocity ampli- tudes, we need a large slip area around the ground surface. This also requires a few MPa cohesive force in friction law at the surface. Finally, short duration of waveform implies a rapid passage of rupture. This behavior should be strongly dependent on frictional parameters. When we take slip-weakening distance larger than 1 m, the du- ration becomes more than 10-15 seconds. We estimate it to be less than 0.8 m. But this estimation is not very strict. For calculating small slip-weakening distance, we need a better resolution in the numerical simulation.

  12. Rheological transitions in high-temperature volcanic fault zones

    NASA Astrophysics Data System (ADS)

    Okumura, Satoshi; Uesugi, Kentaro; Nakamura, Michihiko; Sasaki, Osamu

    2015-05-01

    Silicic magma experiences shear-induced brittle fracturing during its ascent, resulting in the formation of a magmatic fault at the conduit margin. Once the fault is formed, frictional behavior of the fault controls the magma ascent process. We observed torsional deformation of a magmatic fault gouge in situ at temperatures of 800 and 900°C using synchrotron radiation X-ray radiography. The torsional deformation rate was set at 0.1-10 rpm, corresponding to equivalent slip velocities of 2.27 × 10-5-1.74 × 10-3 m s-1 and shear strain rates of 0.014-1.16 s-1. The normal stresses used were 1, 5, and 10 MPa. The magmatic fault showed frictional sliding as well as viscous flow even above the glass transition temperature. The transition between frictional sliding and viscous flow depends on temperature, deformation rate, and normal stress on the fault. At 900°C, the fault showed viscous deformation at a normal stress of 10 MPa, while frictional sliding was predominant at 800°C. We propose the ratio of timescales of fault healing and deformation as a criterion for transition between frictional sliding and viscous flow. The experimentally calibrated criterion infers that frictional sliding is predominant from ~500 m in depth during explosive eruption; this may explain rapid magma ascent without efficient outgassing. Frictional heating would in turn enhance fault healing, resulting in the reverse transition from frictional sliding to viscous flow, followed by deceleration of magma ascent. Therefore, cyclic transitions between frictional sliding and viscous flow are a possible explanation for the cyclic behavior of lava effusion.

  13. Seismic Hazard and Fault Length

    NASA Astrophysics Data System (ADS)

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

    2005-12-01

    If mx is the largest earthquake magnitude that can occur on a fault, then what is mp, the largest magnitude that should be expected during the planned lifetime of a particular structure? Most approaches to these questions rely on an estimate of the Maximum Credible Earthquake, obtained by regression (e.g. Wells and Coppersmith, 1994) of fault length (or area) and magnitude. Our work differs in two ways. First, we modify the traditional approach to measuring fault length, to allow for hidden fault complexity and multi-fault rupture. Second, we use a magnitude-frequency relationship to calculate the largest magnitude expected to occur within a given time interval. Often fault length is poorly defined and multiple faults rupture together in a single event. Therefore, we need to expand the definition of a mapped fault length to obtain a more accurate estimate of the maximum magnitude. In previous work, we compared fault length vs. rupture length for post-1975 earthquakes in Southern California. In this study, we found that mapped fault length and rupture length are often unequal, and in several cases rupture broke beyond the previously mapped fault traces. To expand the geologic definition of fault length we outlined several guidelines: 1) if a fault truncates at young Quaternary alluvium, the fault line should be inferred underneath the younger sediments 2) faults striking within 45° of one another should be treated as a continuous fault line and 3) a step-over can link together faults at least 5 km apart. These definitions were applied to fault lines in Southern California. For example, many of the along-strike faults lines in the Mojave Desert are treated as a single fault trending from the Pinto Mountain to the Garlock fault. In addition, the Rose Canyon and Newport-Inglewood faults are treated as a single fault line. We used these more generous fault lengths, and the Wells and Coppersmith regression, to estimate the maximum magnitude (mx) for the major faults in southern California. Then we compared our mx values with those proposed by CALTRANS, and those assumed in the 2002 USGS/CGS hazard model. To calculate the planning magnitude mp we assumed a truncated Gutenberg-Richter magnitude distribution with parameters a, b, and mx. We fixed b and solved for the a-value in terms of mx, b, and the tectonic moment rate. For many faults mp is relatively insensitive to mx and typically falls off at higher magnitudes because the a-value decreases with increasing mx when the moment rate is constrained. Furthermore, we find that by increasing mx the cumulative earthquake rate actually decreases for smaller magnitude (5 and 6) events. This suggests that fewer magnitude 5 and 6 earthquakes are required to balance the moment budget if larger, but highly infrequent, earthquakes are allowed to occur.

  14. Fault Creep on the Hayward Fault, CA: Implications for Fault Properties and Patterns of Moment Release

    NASA Astrophysics Data System (ADS)

    Malservisi, R.; Furlong, K. P.; Gans, C.

    2001-12-01

    The seismic risk associated with creeping faults such as the Hayward fault (San Francisco Bay Area, CA) will depend on the rate of moment accumulation (slip deficit) on the fault plane, on the specific geometry of locked and free portions of the fault, and on the interactions between the fault zone and the surrounding lithosphere. Using a visco-elastic finite-element model, we have investigated fault zone geometries and physical characteristics that produce the observed surface creep on the Hayward fault, driven by far field plate motions. This differs from most previous analyses in that we do not explicitly specify fault-creep on fault patches, but rather allow the rheology, geometry, and mechanics of the fault system to determine patterns of fault creep. Our model results show that for models that match the observed surface creep data, there is a smooth transition in creep rate from regions free to creep to locked patches. This behavior leads to "creepable" (low friction) areas that accumulate a high slip deficit as compared to other low friction segments of the fault. Interestingly, a comparison of the creep pattern from our results with Hayward Fault microseismicity indicates that events cluster in the locked areas and in transition zones -the "creepable" regions with a high creeping velocity gradient. Furthermore, seismicity seems to be more diffuse around the fault plane in the locked and transition zones than on the `creepable' areas with relatively high creep rates. Although the total amount of seismic moment stored on the Hayward fault does not differ significantly between our model and previous ones, and thus the potential magnitude of earthquakes are similar in all creep models, there is a difference in the location of fault patches with significant slip deficit. Additionally, since in our models there are regions free to creep that still accumulate a high slip deficit, energy release during rupture may vary among the models. That is, if the velocity of rupture propagation on the fault varies with fault friction (i.e. higher velocity in areas with low friction and lower velocity in locked areas), regions of low friction but high slip deficit on our models may become loci of enhanced rate of moment release, changing the patterns of ground shaking at sites along the fault.

  15. The San Andreas Fault 'Supersite' (Invited)

    NASA Astrophysics Data System (ADS)

    Hudnut, K. W.

    2013-12-01

    An expanded and permanent Supersite has been proposed to the Committee on Earth Observation Satellites (CEOS) for the San Andreas Fault system, based upon the successful initial Group on Earth Observations (GEO) Geohazard Supersite for the Los Angeles region from 2009-2013. As justification for the comprehensive San Andreas Supersite, consider the earthquake history of California, in particular the devastating M 7.8 San Francisco earthquake of 1906, which occurred along the San Andreas Fault, as did an earthquake of similar magnitude in 1857 in southern California. Los Angeles was only a small town then, but now the risk exposure has increased for both of California's megacities. Between the San Francisco and Los Angeles urban areas lies a section of the San Andreas Fault known to creep continually, so it has relatively less earthquake hazard. It used to be thought of as capable of stopping earthquakes entering it from either direction. Transitional behavior at either end of the creeping section is known to display a full range of seismic to aseismic slip events and accompanying seismicity and strain transient events. Because the occurrence of creep events is well documented by instrumental networks such as CISN and PBO, the San Andreas Supersite can be expected to be especially effective. A good baseline level of geodetic data regarding past events and strain accumulation and release exists. Many prior publications regarding the occurrence of geophysical phenomena along the San Andreas Fault system mean that in order to make novel contributions, state-of-the-art science will be required within this Supersite region. In more recent years, the 1989 Loma Prieta earthquake struck adjacent to the San Andreas Fault and caused the most damage along the western side of the San Francisco Bay Area. More recently, the concern has focused on the potential for future events along the Hayward Fault along the eastern side of San Francisco Bay. In Southern California, earthquakes struck in 1992 (Landers), 1994 (Northridge) and 1999 (Hector Mine) as well as the 2010 El Mayor - Cucapah (EM-C) earthquake (just south of the US-Mexico border). Of these four notable events, all produced extensive surface faulting except for the 1994 Northridge event, which was close to the Los Angeles urban area on a buried thrust fault. Northridge caused by far the most destruction, topping $20B (US) and resulting in 57 fatalities due to its location under an urban area. The Landers, Hector Mine and EM-C events occurred in desert areas away from major urban centers, and each proved to be a new and unique test-bed for making rapid progress in earthquake science and creative use of geodetic imagery. InSAR studies were linked to GPS deformation and mapping of surface ruptures and seismicity in a series of important papers about these earthquakes. The hazard in California remains extremely high, with tens of millions of people living in close proximity to the San Andreas Fault system as it runs past both San Francisco and Los Angeles. Dense in-situ networks of seismic and geodetic instruments are continually used for research and earthquake monitoring, as well as development of an earthquake early warning capability. Principles of peer review from funding agencies and open data availability will be observed for all data. For all of these reasons, the San Andreas Fault system is highly appropriate for consideration as a world-class permanent Supersite in the GEO framework.

  16. Seismic reflection profiling around the hypocentral area of the 2003 Miyagi-ken Hokubu earthquake (Mj6.4): Reactivated thrust faulting of a Miocene normal fault.

    NASA Astrophysics Data System (ADS)

    Yokokura, T.; Yamaguchi, K.; Kano, N.; Yokota, T.; Tanaka, A.; Ohtaki, T.

    2004-12-01

    The 2003 Miyagi-ken Hokubu (northern Miyagi) earthquake occurred on July 26, which was preceded by the largest foreshock of Mj5.6 and was followed by the largest aftershock of Mj5.5. Although these earthquakes were not so large in magnitude, they caused large damages. The earthquakes occurred just beneath the Asahiyama hills, where exist the active Asahiyama flexure. Aftershock observations delineate a clear fault plane that extends toward the Sue hills in the east, not toward the Asahiyama hills. However neither surface ruptures nor active fault assocciated with the earthquakes were observed in this region. To clarify both the surface extension of the fault and geologic structure of this region, we conducted 17km-long seismic reflection profiling, using a 17.5-ton vibrator. Geologically, this region was subjected rapid EW extension in middle Miocene and thus produced rift basin was filled by the Matsushima-wan Group (syn-rift sediments) which was bounded by a normal fault, the Ishinomaki-wan fault, in the eastern side of the basin. The Matsushima-wan Group was unconformably overlain by the Shida Group (Miocene post-rift sediments). The Shida Group was unconformably overlain by the Pliocene and post-Pliocene sediments. Deformed Pliocene strata show thrust faulting, indicating EW compression after early Pliocene. Detailed data processing reveals that the seismic profile is essentially concordant with the structure inferred from surface geology. A west-dipping fault with about 50 degrees is found beneath the southeastern extension of the Sue hills where the Ishinomaki-wan fault was supposed to extend. The deeper part of the fault extends toward the earthquake fault plane determined by aftershocks and the shallower part shows a thrust-like structure, which indicate basin inversion using this fault. Thus the 2003 Miyagi-ken Hokubu earthquake occurred as reactivated thrust faulting of the Miocene normal fault bounding the eastern side of the rift basin.

  17. An expert system for fault diagnosis in a Space Shuttle main engine

    NASA Technical Reports Server (NTRS)

    Ali, Moonis; Gupta, U. K.

    1990-01-01

    The detection and diagnosis of SSME faults in an early stage is important in order to allow enough time for fault preventive or corrective measurements. Since most of the faults in a complex system like SSME develop rapidly, early detection and diagnosis of faults is critical for the survival of space vehicles. An expert system has been designed for automatic learning, detection, identification, verification, and correction of anomalous propulsion system operations. This paper describes an innovative machine learning approach which is employed for the automatic training of this expert system.

  18. Fluid involvement in normal faulting

    NASA Astrophysics Data System (ADS)

    Sibson, Richard H.

    2000-04-01

    Evidence of fluid interaction with normal faults comes from their varied role as flow barriers or conduits in hydrocarbon basins and as hosting structures for hydrothermal mineralisation, and from fault-rock assemblages in exhumed footwalls of steep active normal faults and metamorphic core complexes. These last suggest involvement of predominantly aqueous fluids over a broad depth range, with implications for fault shear resistance and the mechanics of normal fault reactivation. A general downwards progression in fault rock assemblages (high-level breccia-gouge (often clay-rich) → cataclasites → phyllonites → mylonite → mylonitic gneiss with the onset of greenschist phyllonites occurring near the base of the seismogenic crust) is inferred for normal fault zones developed in quartzo-feldspathic continental crust. Fluid inclusion studies in hydrothermal veining from some footwall assemblages suggest a transition from hydrostatic to suprahydrostatic fluid pressures over the depth range 3-5 km, with some evidence for near-lithostatic to hydrostatic pressure cycling towards the base of the seismogenic zone in the phyllonitic assemblages. Development of fault-fracture meshes through mixed-mode brittle failure in rock-masses with strong competence layering is promoted by low effective stress in the absence of thoroughgoing cohesionless faults that are favourably oriented for reactivation. Meshes may develop around normal faults in the near-surface under hydrostatic fluid pressures to depths determined by rock tensile strength, and at greater depths in overpressured portions of normal fault zones and at stress heterogeneities, especially dilational jogs. Overpressures localised within developing normal fault zones also determine the extent to which they may reutilise existing discontinuities (for example, low-angle thrust faults). Brittle failure mode plots demonstrate that reactivation of existing low-angle faults under vertical σ1 trajectories is only likely if fluid overpressures are localised within the fault zone and the surrounding rock retains significant tensile strength. Migrating pore fluids interact both statically and dynamically with normal faults. Static effects include consideration of the relative permeability of the faults with respect to the country rock, and juxtaposition effects which determine whether a fault is transmissive to flow or acts as an impermeable barrier. Strong directional permeability is expected in the subhorizontal σ2 direction parallel to intersections between minor faults, extension fractures, and stylolites. Three dynamic mechanisms tied to the seismic stress cycle may contribute to fluid redistribution: (i) cycling of mean stress coupled to shear stress, sometimes leading to postfailure expulsion of fluid from vertical fractures; (ii) suction pump action at dilational fault jogs; and, (iii) fault-valve action when a normal fault transects a seal capping either uniformly overpressured crust or overpressures localised to the immediate vicinity of the fault zone at depth. The combination of σ2 directional permeability with fluid redistribution from mean stress cycling may lead to hydraulic communication along strike, contributing to the protracted earthquake sequences that characterise normal fault systems.

  19. Fault management for data systems

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  20. Fault architecture, fault rocks and fault rock properties in carbonate rocks

    NASA Astrophysics Data System (ADS)

    Bauer, Helene; Decker, Kurt

    2010-05-01

    Fault architecture, fault rocks and fault rock properties in carbonate rocks The current study addresses a comparative analysis of fault zones in limestone and dolomite rocks comparing the architecture of fault core and damage zones, fault rocks, and the hydrodynamic properties of faults exposed in the Upper Triassic Wetterstein Fm. of the Hochschwab Massif (Austria). All analysed faults are sinistral strike-slip faults, which formed at shallow crustal depth during the process of eastward lateral extrusion of the Eastern Alps in the Oligocene and Lower Miocene Fault zones in limestone tend to be relatively narrow zones with distinct fault core and damage zones. Fault cores, which include the principle slip surface of the fault, are characterized by cataclastic fault rock associated with slickensides separating strands of catalasite from surrounding host rock or occurring between different types of cataclasite. Cataclasites differ in terms of fragment size, matrix content and the angularity of fragments,. Cataclasite fabrics indicate progressive cataclasis and substantial displacement across the fault rock. Fault core heterogeneity tends to decrease within more evolved (higher displacement) faults. In all fault cores cataclasites are localized within strands, which connect to geometrically complex anastomosing volumes of fault rock. The 3D geometry of such fault cores is difficult to resolve on the outcrop scale. Beside cataclastic flow pressure solution, overprinting cataclastic fabrics, could be documented within fault zones. Damage zones in limestone fault zones are characterized by intensively fractured (jointed) host rock and dilatation breccias, indicating dilatation processes and peripheral wall rock weakening accompanying the growth of the fault zone. Dilatation breccias with high volumes of carbonate cement indicate these processes are related to high fluid pressure and the percolation of large volumes of fluid. Different parts of the damage zones were differentiated on the base of variable fracture densities. Fracture densities (P32 in m² joint surfaces per m³ rock) generally vary along all investigated faults. They are especially high in more evolved (higher displacement) fault zones where they are associated with large-scale Riedel sehars and in parts of the damage zones, that are next to the fault cores. The assessment of the abundance of small-scale fractures uses fracture facies as an empirical classification providing semi-quantitative estimates of fracture density and abundance. Different units were assigned to fracture facies 1 to 4, with fracture facies 4 indicating highest fracture density. Fault zones in dolomite tend to have several fault cores localized within wider zones of fractured wall rock (damage zones), even at low strain. Compared to fault zones with similar displacement in limestone, damage zones in dolomite tend to be wider and have higher fracture densities. Dilatation breccias are more abundant. A clear separation of fault core and damage zone is more difficult. Damage zones observed at the lateral (mode III) tips of the analysed strike-slip faults show that hydraulic fracturing and fluid flow through the propagating fault are of major importance for its evolution. A typical transition from the wall rock ahead of the propagating fault to the core of the slipped fault includes: densely jointed wall rock, wall rock with abundant cement-filled tension gashes, dilatation breccia and cataclasite reworking both dilatation breccia and wall rock. The detailed documentation of different fault zone units is supplemented by porosity measurements in order to assess the hydrogeological properties of the fault zones. High permeability units are first of all located in the damage zones, characterized by high fracture densities. Porosity measurements on fault rocks showed highest porosity (up to 6%) for fractured wall rocks (fracture facies 4) and dilatation breccias (porosity of undeformed wall rock: 1,5 % average, 2 % maximum). Thin sections prove that most of the porosity is carried by uncemented fractures. Fracture porosity therefore is the controlling factor of fault zone permeability. The different types of cataclasite in fault cores show low intra-granular porosities (average 2,5 %) and very low fracture density. They therefore are classified as low-permeability units.

  1. Fault-tolerant processing system

    NASA Technical Reports Server (NTRS)

    Palumbo, Daniel L. (Inventor)

    1996-01-01

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

  2. Fault interaction near Hollister, California

    SciTech Connect

    Mavko, G.M.

    1982-09-10

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

  3. Fault interaction near Hollister, California

    NASA Astrophysics Data System (ADS)

    Mavko, Gerald M.

    1982-09-01

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

  4. Fault current limiter

    DOEpatents

    Darmann, Francis Anthony

    2013-10-08

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

  5. Perspective View, Garlock Fault

    NASA Technical Reports Server (NTRS)

    2000-01-01

    California's Garlock Fault, marking the northwestern boundary of the Mojave Desert, lies at the foot of the mountains, running from the lower right to the top center of this image, which was created with data from NASA's shuttle Radar Topography Mission (SRTM), flown in February 2000. The data will be used by geologists studying fault dynamics and landforms resulting from active tectonics. These mountains are the southern end of the Sierra Nevada and the prominent canyon emerging at the lower right is Lone Tree canyon. In the distance, the San Gabriel Mountains cut across from the leftside of the image. At their base lies the San Andreas Fault which meets the Garlock Fault near the left edge at Tejon Pass. The dark linear feature running from lower right to upper left is State Highway 14 leading from the town of Mojave in the distance to Inyokern and the Owens Valley in the north. The lighter parallel lines are dirt roads related to power lines and the Los Angeles Aqueduct which run along the base of the mountains.

    This type of display adds the important dimension of elevation to the study of land use and environmental processes as observed in satellite images. The perspective view was created by draping a Landsat satellite image over an SRTM elevation model. Topography is exaggerated 1.5 times vertically. The Landsat image was provided by the United States Geological Survey's Earth Resources Observations Systems (EROS) Data Center, Sioux Falls, South Dakota.

    Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11,2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise,Washington, DC.

    Size: Varies in a perspective view Location: 35.25 deg. North lat., 118.05 deg. West lon. Orientation: Looking southwest Original Data Resolution: SRTM and Landsat: 30 meters (99 feet) Date Acquired: February 16, 2000

  6. 20 CFR 404.507 - Fault.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

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

  7. 20 CFR 404.507 - Fault.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

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

  8. 20 CFR 404.507 - Fault.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

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

  9. Final Technical Report: PV Fault Detection Tool.

    SciTech Connect

    King, Bruce Hardison; Jones, Christian Birk

    2015-12-01

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

  10. Frictional resistance of faults during accelerating and decelerating earthquake slip

    NASA Astrophysics Data System (ADS)

    Sone, Hiroki; Shimamoto, Toshihiko

    2009-10-01

    The dynamic friction of faults during earthquake slip is a critical control on earthquake ruptures in the crust. Extrapolation of brittle crack theories to natural earthquakes has led to the commonly held view that fault friction reduces during rapid earthquake slip, a process known as slip-weakening. High-velocity gouge experiments and recent analyses of thermal pressurization and frictional melting support such a notion; however, these studies dealt with constant rates of slip along faults. Here we present the results of experiments aimed at understanding the frictional behaviour of fault zone materials under variable slip rates-conditions that are more representative of natural earthquakes. Our results show that faults undergo a sequence of strengthening, weakening and healing during acceleration and deceleration of slip. Such a sequence may be explained by the extrapolation of rate-and-state frictional behaviour at low slip velocities to more realistic slip rates, but involving different physical mechanisms and a different scale. The initial strengthening should impose a barrier for rupture growth into large earthquakes. The healing on decelerating fault motion may lead to pulse-like earthquake ruptures and static stress drops that are low in comparison with the dynamic stress changes.

  11. Self-constrained inversion of microgravity data along a segment of the Irpinia fault

    NASA Astrophysics Data System (ADS)

    Lo Re, Davide; Florio, Giovanni; Ferranti, Luigi; Ialongo, Simone; Castiello, Gabriella

    2016-01-01

    A microgravity survey was completed to precisely locate and better characterize the near-surface geometry of a recent fault with small throw in a mountainous area in the Southern Apennines (Italy). The site is on a segment of the Irpinia fault, which is the source of the M6.9 1980 earthquake. This fault cuts a few meter of Mesozoic carbonate bedrock and its younger, mostly Holocene continental deposits cover. The amplitude of the complete Bouguer anomaly along two profiles across the fault is about 50 μGal. The data were analyzed and interpreted according to a self-constrained strategy, where some rapid estimation of source parameters was later used as constraint for the inversion. The fault has been clearly identified and localized in its horizontal position and depth. Interesting features in the overburden have been identified and their interpretation has allowed us to estimate the fault slip-rate, which is consistent with independent geological estimates.

  12. Internal structure, fault rocks, and inferences regarding deformation, fluid flow, and mineralization in the seismogenic Stillwater normal fault, Dixie Valley, Nevada

    USGS Publications Warehouse

    Caine, J.S.; Bruhn, R.L.; Forster, C.B.

    2010-01-01

    Outcrop mapping and fault-rock characterization of the Stillwater normal fault zone in Dixie Valley, Nevada are used to document and interpret ancient hydrothermal fluid flow and its possible relationship to seismic deformation. The fault zone is composed of distinct structural and hydrogeological components. Previous work on the fault rocks is extended to the map scale where a distinctive fault core shows a spectrum of different fault-related breccias. These include predominantly clast-supported breccias with angular clasts that are cut by zones containing breccias with rounded clasts that are also clast supported. These are further cut by breccias that are predominantly matrix supported with angular and rounded clasts. The fault-core breccias are surrounded by a heterogeneously fractured damage zone. Breccias are bounded between major, silicified slip surfaces, forming large pod-like structures, systematically oriented with long axes parallel to slip. Matrix-supported breccias have multiply brecciated, angular and rounded clasts revealing episodic deformation and fluid flow. These breccias have a quartz-rich matrix with microcrystalline anhedral, equant, and pervasively conformable mosaic texture. The breccia pods are interpreted to have formed by decompression boiling and rapid precipitation of hydrothermal fluids whose flow was induced by coseismic, hybrid dilatant-shear deformation and hydraulic connection to a geothermal reservoir. The addition of hydrothermal silica cement localized in the core at the map scale causes fault-zone widening, local sealing, and mechanical heterogeneities that impact the evolution of the fault zone throughout the seismic cycle. ?? 2010.

  13. Mercury's global fabric of thrust faults

    NASA Astrophysics Data System (ADS)

    Klimczak, C.; Byrne, P. K.; Solomon, S. C.

    2014-12-01

    Mercury's global tectonic history is thought to have been shaped by two major processes: tidal despinning and global contraction. Each process is expected to have produced a distinctive global stress field and resultant fault pattern. Data from three years of orbital operations by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft reveal thousands of thrust faults that are attributed to global contraction, but no global signature of tidal despinning has been conclusively documented. Global contraction operated throughout an extended portion of Mercury's geologic history, whereas tidal despinning likely operated for a shorter duration. Therefore, any tidal despinning pattern, if not entirely obliterated by the late heavy bombardment, either would have formed together with global contraction, or would have been modified by global contraction after despinning was complete. Here, we reassess global fracture patterns predicted to result from tidal despinning alone, and from a combination of tidal despinning and global contraction. We specifically make use of rock strength and deformability parameters appropriate for Mercury's fractured lithosphere. Our results indicate that a tidal despinning pattern would consist only of a global set of opening-mode fractures (joints) in the upper part of the lithosphere, whereas the combination of tidal despinning and global contraction would have produced a global population of thrust faults, with no preferred orientations in the polar regions but with an increasing preference for north-south orientations toward the equator. If an equatorial bulge from an early state of rapid spin were supported by Mercury's lithosphere, two end-member scenarios for the timing and duration of these two processes can be considered. In one, tidal despinning predated global contraction; in the other, tidal despinning and global contraction temporally overlapped. We test the predictions for both scenarios against the mapped distribution and orientations of Mercury's tectonic landforms. The global pattern of thrust faults is generally consistent with predictions for the scenario under which tidal despinning and global contraction temporally overlapped.

  14. SFT: Scalable Fault Tolerance

    SciTech Connect

    Petrini, Fabrizio; Nieplocha, Jarek; Tipparaju, Vinod

    2006-04-15

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

  15. Colorado Regional Faults

    SciTech Connect

    Hussein, Khalid

    2012-02-01

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

  16. Central Asia Active Fault Database

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  17. Fault deformation mechanisms and fault rocks in micritic limestones: Examples from Corinth rift normal faults

    NASA Astrophysics Data System (ADS)

    Bussolotto, M.; Benedicto, A.; Moen-Maurel, L.; Invernizzi, C.

    2015-08-01

    A multidisciplinary study investigates the influence of different parameters on fault rock architecture development along normal faults affecting non-porous carbonates of the Corinth rift southern margin. Here, some fault systems cut the same carbonate unit (Pindus), and the gradual and fast uplift since the initiation of the rift led to the exhumation of deep parts of the older faults. This exceptional context allows superficial active fault zones and old exhumed fault zones to be compared. Our approach includes field studies, micro-structural (optical microscope and cathodoluminescence), geochemical analyses (δ13C, δ18O, trace elements) and fluid inclusions microthermometry of calcite sin-kinematic cements. Our main results, in a depth-window ranging from 0 m to about 2500 m, are: i) all cements precipitated from meteoric fluids in a close or open circulation system depending on depth; ii) depth (in terms of P/T condition) determines the development of some structures and their sealing; iii) lithology (marly levels) influences the type of structures and its cohesive/non-cohesive nature; iv) early distributed rather than final total displacement along the main fault plane is the responsible for the fault zone architecture; v) petrophysical properties of each fault zone depend on the variable combination of these factors.

  18. Overview of the Southern San Andreas Fault Model

    USGS Publications Warehouse

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

    2008-01-01

    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 results. A distinctive aspect of the current model is that the probability is higher at both ends of the fault and that the ends have a much greater fraction of smaller events. There is a significant difference in the likelihood of large (M 7.7-8.0) earthquakes along the fault from north to south, with large 1857-like events common on the northern half of the southern San Andreas fault but relatively few M 7.7-8.0 expected on the southern half.

  19. The Growth of Simple Mountain Ranges: 2. Geomorphic Evolution at Fault Linkage Sites

    NASA Astrophysics Data System (ADS)

    Dawers, N. H.; Densmore, A. L.; Davis, A. M.; Gupta, S.

    2002-12-01

    Large normal faults grow partly through linkage of fault segments and partly by fault tip propagation. The process by which fault segments interact and link is critical to understanding how topography is created along fault-bounded ranges. Structural studies and numerical models have shown that fault linkage is accompanied by localised increased displacement rate, which in turn drives rapid base level fall at the evolving range front. The changes in both along-strike fault structure and base level are most pronounced at and adjacent to sites of fault linkage. These areas, known as relay zones, thus preserve clues to both the tectonic history and the geomorphic evolution of large fault-bounded mountain ranges. We discuss the temporal and spatial constraints on the evolution of footwall-range topography, by comparing a number of active fault linkage sites, using field and DEM observations of the spatial pattern of footwall denudation. In particular, we focus on sites in Pleasant Valley, Nevada (Pearce and Tobin fault segments) and in the northeastern Basin and Range (the Beaverhead fault, Idaho, and the Star Valley fault, Wyoming). The study areas represent different stages in the structural and geomorphic evolution of relay zones, and allow us to propose a developmental model of large fault evolution and landscape response. Early in the growth of fault segments into an overlapping geometry, catchments may form within the evolving relay. However, increasing displacement rate associated with fault interaction and linkage makes these catchments prone to capture by streams that have incised headward from the range front. This scenario leads to locally increased footwall denudation in the vicinity of the capture site. Longitudinal profiles of streams differ with respect to position along relays and whether or not any particular stream has been able to capture early-formed drainages. The restricted space between interacting en echelon fault segments helps preserve close stream spacing, similar to that seen at the distal tips of footwall ranges. We hypothesise that there are 2 key controls on relay landscape development: 1) the width of the en echelon overstep, which controls the overall level of fault interaction and the detailed rock uplift pattern in the relay, and 2) the relative timeframe of linkage within the evolving fault system.

  20. Nano-grains form carbonate "fault mirrors"

    NASA Astrophysics Data System (ADS)

    Siman-Tov, Shalev; Aharonov, Einat; Sagy, Amir; Emmanuel, Simon

    2013-04-01

    Many faults are characterized by naturally polished glossy surfaces, termed fault mirrors (FMs), which form during slip. Recent experiments also find that FMs form during rapid (but not slow) sliding between rock surfaces, and that FM formation coincides with pronounced friction reduction. The structure of FMs and the mechanism of their formation are thus important for understanding the mechanics of frictional sliding in general, and during earthquakes in particular. Here we characterize the small-scale structure of natural carbonate FMs from 3 different faults along a tectonically active region of the Dead Sea Transform. Atomic force microscopy measurements indicate that the FMs possess extremely smooth surface topography, accounting for their mirror-like appearance. Electron microscope characterization tools revealed a thin (< 1 µm) layer, composed of tightly packed nano-scaled grains, coating a rougher layer composed of micron-size calcite crystals. The crystals contain closely-spaced, plastically-formed, mechanical twins, which define new sub-grain boundaries. The narrow sub-grains are observed to break into sub-micron pieces near the sheared surface. This observation suggests a new brittle-ductile mechanism for nano-grain formation. Our observations further suggest that FMs require two main ingredients: (i) Nano grains and (ii) a hard and very smooth surface, probably formed by nano-grain sintering, a plastic process requiring high temperatures that arise only during rapid enough sliding. Both nano-grains and nano-scale-smooth surfaces were previously suggested to induce frictional weakening. We discuss possible physical processes that may control the observed connection between FM formation and frictional weakening.

  1. A survey of an introduction to fault diagnosis algorithms

    NASA Technical Reports Server (NTRS)

    Mathur, F. P.

    1972-01-01

    This report surveys the field of diagnosis and introduces some of the key algorithms and heuristics currently in use. Fault diagnosis is an important and a rapidly growing discipline. This is important in the design of self-repairable computers because the present diagnosis resolution of its fault-tolerant computer is limited to a functional unit or processor. Better resolution is necessary before failed units can become partially reuseable. The approach that holds the greatest promise is that of resident microdiagnostics; however, that presupposes a microprogrammable architecture for the computer being self-diagnosed. The presentation is tutorial and contains examples. An extensive bibliography of some 220 entries is included.

  2. 20 CFR 404.507 - Fault.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Officer § 404.507 Fault. Fault as used in without fault (see § 404.506 and 42 CFR 405.355) applies only to..., educational, or linguistic limitations (including any lack of facility with the English language)...

  3. 20 CFR 404.507 - Fault.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Officer § 404.507 Fault. Fault as used in without fault (see § 404.506 and 42 CFR 405.355) applies only to..., educational, or linguistic limitations (including any lack of facility with the English language)...

  4. Chip level simulation of fault tolerant computers

    NASA Technical Reports Server (NTRS)

    Armstrong, J. R.

    1982-01-01

    Chip-level modeling techniques in the evaluation of fault tolerant systems were researched. A fault tolerant computer was modeled. An efficient approach to functional fault simulation was developed. Simulation software was also developed.

  5. Frictional Heterogeneities Along Carbonate Faults

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  6. The Lawanopo Fault, central Sulawesi, East Indonesia

    NASA Astrophysics Data System (ADS)

    Natawidjaja, Danny Hilman; Daryono, Mudrik R.

    2015-04-01

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

  7. Arc fault detection system

    DOEpatents

    Jha, K.N.

    1999-05-18

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

  8. Arc fault detection system

    DOEpatents

    Jha, Kamal N.

    1999-01-01

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

  9. Faulted Sedimentary Rocks

    NASA Technical Reports Server (NTRS)

    2004-01-01

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

  10. Fault Tolerant State Machines

    NASA Technical Reports Server (NTRS)

    Burke, Gary R.; Taft, Stephanie

    2004-01-01

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

  11. Improving Multiple Fault Diagnosability using Possible Conflicts

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

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

    SciTech Connect

    Cumbest, R.J.

    2000-11-14

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

  13. The Dynamics of Fault Zones

    NASA Astrophysics Data System (ADS)

    Mooney, W. D.; Beroza, G.; Kind, R.

    2006-05-01

    Geophysical studies of the Earth's crust, including fault zones, have developed over the past 80 years. Among the first methods to be employed, seismic refraction and reflection profiles were recorded in the North American Gulf Coast to detect salt domes which were known to trap hydrocarbons. Seismic methods continue to be the most important geophysical technique in use today due to the methods' relatively high accuracy, high resolution, and great depth of penetration. However, in the past decade, a much expanded repertoire of seismic and non-seismic techniques have been brought to bear on studies of the Earth's crust and uppermost mantle. Important insights have also been obtained using seismic tomography, measurements of seismic anisotropy, fault zone guided waves, borehole surveys, and geo-electrical, magnetic, and gravity methods. In this presentation, we briefly review recent geophysical progress in the study of the structure and internal properties of faults zones, from their surface exposures to their lower limit. We focus on the structure of faults within continental crystalline and competent sedimentary rock rather than within the overlying, poorly consolidated sedimentary rocks. A significant body of literature exists for oceanic fracture zones, however, due to space limitations we restrict this review to faults within and at the margins of the continents. We also address some unanswered questions, including: 1) Does fault-zone complexity, as observed at the surface, extend to great depth, or do active faults become thin simple planes at depth? and 2) How is crustal deformation accommodated within the lithospheric mantle?

  14. ANNs pinpoint underground distribution faults

    SciTech Connect

    Glinkowski, M.T.; Wang, N.C.

    1995-10-01

    Many offline fault location techniques in power distribution circuits involve patrolling along the lines or cables. In overhead distribution lines, most of the failures can be located quickly by visual inspection without the aid of special equipment. However, locating a fault in underground cable systems is more difficult. It involves additional equipment (e.g., thumpers, radars, etc.) to transform the invisibility of the cable into other forms of signals, such as acoustic sound and electromagnetic pulses. Trained operators must carry the equipment above the ground, follow the path of the signal, and draw lines on their maps in order to locate the fault. Sometimes, even smelling the burnt cable faults is a way of detecting the problem. These techniques are time consuming, not always reliable, and, as in the case of high-voltage dc thumpers, can cause additional damage to the healthy parts of the cable circuit. Online fault location in power networks that involve interconnected lines (cables) and multiterminal sources continues receiving great attention, with limited success in techniques that would provide simple and practical solutions. This article features a new online fault location technique that: uses the pattern recognition feature of artificial neural networks (ANNs); utilizes new capabilities of modern protective relaying hardware. The output of the neural network can be graphically displayed as a simple three-dimensional (3-D) chart that can provide an operator with an instantaneous indication of the location of the fault.

  15. Subaru FATS (fault tracking system)

    NASA Astrophysics Data System (ADS)

    Winegar, Tom W.; Noumaru, Junichi

    2000-07-01

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

  16. Fault Identification by Unsupervised Learning Algorithm

    NASA Astrophysics Data System (ADS)

    Nandan, S.; Mannu, U.

    2012-12-01

    Contemporary fault identification techniques predominantly rely on the surface expression of the fault. This biased observation is inadequate to yield detailed fault structures in areas with surface cover like cities deserts vegetation etc and the changes in fault patterns with depth. Furthermore it is difficult to estimate faults structure which do not generate any surface rupture. Many disastrous events have been attributed to these blind faults. Faults and earthquakes are very closely related as earthquakes occur on faults and faults grow by accumulation of coseismic rupture. For a better seismic risk evaluation it is imperative to recognize and map these faults. We implement a novel approach to identify seismically active fault planes from three dimensional hypocenter distribution by making use of unsupervised learning algorithms. We employ K-means clustering algorithm and Expectation Maximization (EM) algorithm modified to identify planar structures in spatial distribution of hypocenter after filtering out isolated events. We examine difference in the faults reconstructed by deterministic assignment in K- means and probabilistic assignment in EM algorithm. The method is conceptually identical to methodologies developed by Ouillion et al (2008, 2010) and has been extensively tested on synthetic data. We determined the sensitivity of the methodology to uncertainties in hypocenter location, density of clustering and cross cutting fault structures. The method has been applied to datasets from two contrasting regions. While Kumaon Himalaya is a convergent plate boundary, Koyna-Warna lies in middle of the Indian Plate but has a history of triggered seismicity. The reconstructed faults were validated by examining the fault orientation of mapped faults and the focal mechanism of these events determined through waveform inversion. The reconstructed faults could be used to solve the fault plane ambiguity in focal mechanism determination and constrain the fault orientations for finite source inversions. The faults produced by the method exhibited good correlation with the fault planes obtained by focal mechanism solutions and previously mapped faults.

  17. Fault Injection Campaign for a Fault Tolerant Duplex Framework

    NASA Technical Reports Server (NTRS)

    Sacco, Gian Franco; Ferraro, Robert D.; von llmen, Paul; Rennels, Dave A.

    2007-01-01

    Fault tolerance is an efficient approach adopted to avoid or reduce the damage of a system failure. In this work we present the results of a fault injection campaign we conducted on the Duplex Framework (DF). The DF is a software developed by the UCLA group [1, 2] that uses a fault tolerant approach and allows to run two replicas of the same process on two different nodes of a commercial off-the-shelf (COTS) computer cluster. A third process running on a different node, constantly monitors the results computed by the two replicas, and eventually restarts the two replica processes if an inconsistency in their computation is detected. This approach is very cost efficient and can be adopted to control processes on spacecrafts where the fault rate produced by cosmic rays is not very high.

  18. Aerial photographic interpretation of lineaments and faults in late Cenozoic deposits in the eastern parts of the Saline Valley 1:100, 000 quadrangle, Nevada and California, and the Darwin Hills 1:100, 000 quadrangle, California

    SciTech Connect

    Reheis, M.C.

    1991-09-01

    Faults and fault-related lineaments in Quaternary and late Tertiary deposits in the southern part of the Walker Lane are potentially active and form patterns that are anomalous compared to those in most other areas of the Great Basin. Two maps at a scale of 1:100,000 summarize information about lineaments and faults in the area around and southwest of the Death Valley-Furnace Creek fault system based on extensive aerial-photo interpretation, limited field interpretation, limited field investigations, and published geologic maps. There are three major fault zones and two principal faults in the Saline Valley and Darwin Hills 1:100,000 quadrangles. (1) The Death Valley-Furnace Creek fault system and (2) the Hunter Mountain fault zone are northwest-trending right-lateral strike-slip fault zones. (3) The Panamint Valley fault zone and associated Towne Pass and Emigrant faults are north-trending normal faults. The intersection of the Hunter Mountain and Panamint Valley fault zones is marked by a large complex of faults and lineaments on the floor of Panamint Valley. Additional major faults include (4) the north-northwest-trending Ash Hill fault on the west side of Panamint Valley, and (5) the north-trending range-front Tin Mountain fault on the west side of the northern Cottonwood Mountains. The most active faults at present include those along the Death Valley-Furnace Creek fault system, the Tin Mountain fault, the northwest and southeast ends of the Hunter Mountain fault zone, the Ash Hill fault, and the fault bounding the west side of the Panamint Range south of Hall Canyon. Several large Quaternary landslides on the west sides of the Cottonwood Mountains and the Panamint Range apparently reflect slope instability due chiefly to rapid uplift of these ranges. 16 refs.

  19. Finding faults with the data

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

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

  20. Method of locating ground faults

    NASA Technical Reports Server (NTRS)

    Patterson, Richard L. (Inventor); Rose, Allen H. (Inventor); Cull, Ronald C. (Inventor)

    1994-01-01

    The present invention discloses a method of detecting and locating current imbalances such as ground faults in multiwire systems using the Faraday effect. As an example, for 2-wire or 3-wire (1 ground wire) electrical systems, light is transmitted along an optical path which is exposed to magnetic fields produced by currents flowing in the hot and neutral wires. The rotations produced by these two magnetic fields cancel each other, therefore light on the optical path does not read the effect of either. However, when a ground fault occurs, the optical path is exposed to a net Faraday effect rotation due to the current imbalance thereby exposing the ground fault.

  1. Automatic distribution fault locating system

    SciTech Connect

    Hager, G.E.; Bear, R.N.M.; Baum, A.S.

    1995-12-31

    An automated fault locating system was designed and implemented for the Colorado River Agency (CRA) 12.5/7.2 kV distribution system. This automated fault locating system (FLS) was integrated into the Supervisory Control and Data Acquisition (SCADA) system which was installed at a hydro power plant. This FLS offers several benefits to the CRA distribution system. These benefits include: reduced outage time; help in locating momentary faults; enhanced safety to the line crews; provide notification of an outage without receiving calls from the consumer; and decreased overtime.

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

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

  3. 20 CFR 410.561b - Fault.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

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

  4. 20 CFR 410.561b - Fault.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

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

  5. 22 CFR 17.3 - Fault.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

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

  6. 22 CFR 17.3 - Fault.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

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

  7. 22 CFR 17.3 - Fault.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

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

  8. 22 CFR 17.3 - Fault.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

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

  9. 22 CFR 17.3 - Fault.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

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

  10. Expert System Detects Power-Distribution Faults

    NASA Technical Reports Server (NTRS)

    Walters, Jerry L.; Quinn, Todd M.

    1994-01-01

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

  11. Moment accumulation rate on faults in California inferred from viscoelastic earthquake cycle models (Invited)

    NASA Astrophysics Data System (ADS)

    Johnson, K. M.

    2009-12-01

    Calculations of moment accumulation rates on active faults require knowledge of long-term fault slip rates and the area of the fault that is locked interseismically. These parameters are routinely estimated from geodetic data using elastic block models with back slip on dislocations in an elastic half-space. Yet, the elastic models are inconsistent with studies that infer postseismic viscous flow in the lower crust and mantle occurring for decades following large earthquakes. Viscous flow in the lower crust and mantle generates rapid, localized deformation early in the earthquake cycle and slower, more diffuse deformation later in the cycle. Elastic models which neglect this time-dependent flow process may lead to biased estimates of fault slip rates and locking distribution. To address this issue we have developed a three-dimensional earthquake cycle model consisting of fault-bounded blocks in an elastic crust overlying a viscoelastic lower crust and uppermost mantle. It is a kinematic model in which long-term motions of fault-bounded blocks is imposed. Interseismic locking of faults and associated deformation is modeled with steady back-slip on faults and imposed periodic earthquakes. Creep on unlocked portions of the faults occurs at constant stress and therefore the instantaneous creep rate is proportional to the instantaneous stressing rate on the fault. We compare geologic slip rate estimates in southern California with model estimates using GPS data and show that elastic block models underpredict slip rates on several faults that are late in the earthquake cycle and overpredict slip rates on faults that are early in the earthquake cycle. The viscoelastic cycle model, constrained by earthquake timing from the geologic record, predicts fault slip rates that are entirely consistent with geologic estimates for all major faults in southern California. For northern California, fault slip rate estimates using geodetic data appear not to be strongly dependent on model assumptions and are generally consistent with geologic estimates; therefore we focus on estimates of the distribution of interseismic locking of faults. We constrain the locking distribution using nearly a century of triangulation measurements of strain following the M7.8 1906 San Francisco earthquake, contemporary GPS velocities, geologic slip rate and earthquake timing data, and the viscoelastic earthquake cycle model with spatially variable distributions of locking and stress-driven creep. We find considerable lateral variations in locking depths in the San Francisco Bay area. Compared with our models of spatially variable locking distribution, models that assume a typical 15 km uniform locking depth overpredict the moment accumulation rate by a factor of 2-3 on the Peninsular San Andreas, Calaveras, Rodgers Creek, and Green Valley faults.

  12. Spontaneous rupture on irregular faults

    NASA Astrophysics Data System (ADS)

    Liu, C.

    2014-12-01

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

  13. Cell boundary fault detection system

    SciTech Connect

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

    2009-05-05

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

  14. A fault-tolerant clock

    NASA Technical Reports Server (NTRS)

    Daley, W. P.; Mckenna, J. F., Jr.

    1973-01-01

    Computers must operate correctly even though one or more of components have failed. Electronic clock has been designed to be insensitive to occurrence of faults; it is substantial advance over any known clock.

  15. Fault Creep and Kinematics of the Chihshang Fault in Eastern Taiwan Derived from the PSInSAR and Geodetic Techniques

    NASA Astrophysics Data System (ADS)

    Lai, Y. P.; Ching, K. E.; Chen, K. H.; Lee, J. C.; Chang, C. P.; Yen, J. Y.

    2014-12-01

    The Chihshang fault, one segment of the plate suture between the Eurasian and the Philippine Sea plates in eastern Taiwan, is a rapid creeping reverse fault, which has been considered to show interseismic creep near the surface while contemporaneously being capable of producing large earthquakes at depth. In order to understand its seismic hazard, we integrate the near-fault total station measurements and the data from 10 campaign GPS stations for analyzing the nature of creep with 25 continuous GPS observations and the data from PsInSAR method for recognizing the kinematics of deep seismogenic zone. The GPS coordinate daily solution is calculated using the software Bernese v.5.0 under the ITRF2008. Horizontal velocity field is relative to the station S01R located in Penghu island. The average velocity of six campaign-mode GPS stations is about 47.9 mm/yr with the azimuth of 296° at southern segment of the Chihshang fault. The average velocity of the other four campaign-mode GPS stations is about 67.5 mm/yr with the azimuth of 307° at the central segment of the fault. Continuous GPS stations show a great horizontal velocity decreases from hanging wall (eastern side) to footwall (western side). Velocities for stations on the eastern side of the Chihshang fault are 62.5-84.4 mm/yr in directions 291°-314°, whereas those on the western side of the Chihshang fault hanging wall are 24.8-45.3 mm/yr in directions 294°-304°. A major discontinuity about 30 mm/yr on the rate of crustal motion across the Chihshang fault is believed to be the aseismic slip along the fault. Next step, the PSInSAR methods and total station data will be used and integrated with other geodetic data to monitor a wide range of surface activities in the Eastern Taiwan. Finally we hope to reveal the spatiotemporal nature of the creep on the Chihshang fault for helping us associating the creep with potential lithological controls, and providing a new perspective to better understand the underlying causes and mechanisms.

  16. Fault-tolerant rotary actuator

    DOEpatents

    Tesar, Delbert

    2006-10-17

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

  17. Fault Tree Analysis: A Bibliography

    NASA Technical Reports Server (NTRS)

    2000-01-01

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

  18. Seismic fault zone trapped noise

    NASA Astrophysics Data System (ADS)

    Hillers, G.; Campillo, M.; Ben-Zion, Y.; Roux, P.

    2014-07-01

    Systematic velocity contrasts across and within fault zones can lead to head and trapped waves that provide direct information on structural units that are important for many aspects of earthquake and fault mechanics. Here we construct trapped waves from the scattered seismic wavefield recorded by a fault zone array. The frequency-dependent interaction between the ambient wavefield and the fault zone environment is studied using properties of the noise correlation field. A critical frequency fc ≈ 0.5 Hz defines a threshold above which the in-fault scattered wavefield has increased isotropy and coherency compared to the ambient noise. The increased randomization of in-fault propagation directions produces a wavefield that is trapped in a waveguide/cavity-like structure associated with the low-velocity damage zone. Dense spatial sampling allows the resolution of a near-field focal spot, which emerges from the superposition of a collapsing, time reversed wavefront. The shape of the focal spot depends on local medium properties, and a focal spot-based fault normal distribution of wave speeds indicates a ˜50% velocity reduction consistent with estimates from a far-field travel time inversion. The arrival time pattern of a synthetic correlation field can be tuned to match properties of an observed pattern, providing a noise-based imaging tool that can complement analyses of trapped ballistic waves. The results can have wide applicability for investigating the internal properties of fault damage zones, because mechanisms controlling the emergence of trapped noise have less limitations compared to trapped ballistic waves.

  19. MER surface fault protection system

    NASA Technical Reports Server (NTRS)

    Neilson, Tracy

    2005-01-01

    The Mars Exploration Rovers surface fault protection design was influenced by the fact that the solar-powered rovers must recharge their batteries during the day to survive the night. the rovers needed to autonomously maintain thermal stability, initiate safe and reliable communication with orbiting assets or directly to Earth, while maintaining energy balance. This paper will describe the system fault protection design for the surface phase of the mission.

  20. Fluid transport by solitary waves along growing faults. A field example from the South Eugene Island Basin, Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Revil, A.; Cathles, L. M.

    2002-09-01

    The Red Fault system is one of the main growth faults found in the South Eugene Island Basin, a salt withdrawal minibasin located offshore Louisiana, in the Gulf of Mexico. This fault system corresponds to a lateral boundary between fluid overpressured compartments. In addition, there is a set of observations indicating that the Red Fault system exhibits rapid episodic migration of fluids. This fault represents an example of preferential pathway for the upward episodic migration of overpressured hydrocarbons from deep, heavily pressured, compartments on time scales of years. The migrations of fluids into active growing faults could take the form of propagating surges (solitary waves) that propagate upward along the fault planes in a wave-like manner at km/yr. Solitary waves represent a very efficient mechanism for the upward transport of fluids along growth faults in sedimentary basins generating its own permeability. In addition, this mechanism is compatible with the fact that the fault plane is observed to sustain a static pore fluid pressure difference between its two sides. The propagation of solitary waves in active growth faults appears as a fundamental mechanism to understand the nature of upward fast migration of fluids along active growth faults in compartimentalized sedimentary basins.

  1. Flash Heating and Fault Zone Evolution

    NASA Astrophysics Data System (ADS)

    Chen, J.; Rempel, A. W.

    2012-12-01

    Accurate descriptions of strength evolution are required in predictive models of fault-zone behavior during earthquakes. At low sliding rates, frictional resistance between fault rocks is much higher than the shear stress that is typically inferred to be present during earthquakes. Laboratory experiments confirm that the friction coefficient drops at high sliding rates, and there are also suggestions that strengthening, possibly related to an increase in the area of viscous melt patches, may occur after this initial weakening stage. Most weakening mechanisms that have been proposed do not predict such strengthening, which may exert an important control on the thickness of the zones over which shear is accommodated during earthquakes. We propose a micro-mechanical model of flash heating that describes how shear resistance evolves at the asperity scale as a result of distributed deformation over a weak layer that grows during the brief lifetime of each asperity contact. Beyond a threshold weakening velocity, our model predicts that friction should decrease with slip rate since higher sliding speeds cause the weak layer to thicken more rapidly. A comparison with published experimental data from a range of mineral systems shows good agreement with the model predictions when two dimensionless fitting parameters are chosen appropriately. At higher sliding rates and/or elevated temperatures, our model predicts that the frictional rate dependence should transition from velocity weakening to become velocity strengthening because decreases in the contact lifetime with slip rate cause the average asperity strength to increase. Combining this frictional constitutive behavior with a description of the thermal pressurization of pore fluids, we predict the evolution of shear-zone thickness, temperature, and pore pressure during a model earthquake along a mature fault.

  2. Hayward Fault rate constraints at Berkeley: Evaluation of the 335-meter Strawberry Creek offset

    NASA Astrophysics Data System (ADS)

    Williams, P. L.

    2007-12-01

    At UC Berkeley the active channel of Strawberry Creek is offset 335 meters by the Hayward fault and two abandoned channels of Strawberry Creek are laterally offset 580 and 730 meters. These relationships record the displacement of the northern Hayward fault at Berkeley over a period of tens of millennia. The Strawberry Creek site has a similar geometry to the central San Andreas fault's Wallace Creek site, which arguably provides the best geological evidence of "millennial" fault kinematics in California (Sieh and Jahns, 1984). Slip rate determinations are an essential component of overall hazard evaluation for the Hayward fault, and this site is ripe to disclose a long-term form of this parameter, to contrast with geodetic and other geological rate evidence. Large offsets at the site may lower uncertainty in the rate equation relative to younger sites, as the affect of stream abandonment age, generally the greatest source of rate uncertainty, is greatly reduced. This is helpful here because it more-than-offsets uncertainties resulting from piercing projections to the fault. Strawberry Creek and its ancestral channels suggest west-side-up vertical deformation across the Hayward fault at this location. The development of the vertical deformation parameter will complement ongoing geodetic measurements, particularly InSAR, and motivate testing of other geological constraints. Up-to-the-west motion across the Hayward fault at Berkeley has important implications for the partitioning of strain and kinematics of the northern Hayward fault, and may explain anomalous up-on-the-west landforms elsewhere along the fault. For example, geological features of the western Berkeley Hills are consistent with rapid and recent uplift to the west of the fault. On the basis of a preliminary analysis of the offset channels of Strawberry Creek, up-to-the-west uplift is about 0.5mm/yr across the Hayward fault at Berkeley. If this is in fact the long-term rate, the 150 m height of the Hills to the northwest of the Strawberry Creek site was produced during the past about 300,000 years by a significant dip- slip (thrust) component of Hayward fault motion. Rapid and recent uplift of some portions of the East Bay Hills has important implications for fault geometries and slope stability, and should strongly influence the investigation fault hazards in areas that are more complexly deformed.

  3. Passive fault current limiting device

    DOEpatents

    Evans, Daniel J.; Cha, Yung S.

    1999-01-01

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

  4. Passive fault current limiting device

    DOEpatents

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

    1999-04-06

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

  5. Software Fault Tolerance: A Tutorial

    NASA Technical Reports Server (NTRS)

    Torres-Pomales, Wilfredo

    2000-01-01

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

  6. Normal fault earthquakes or graviquakes.

    PubMed

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

    2015-01-01

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

  7. Normal fault earthquakes or graviquakes

    PubMed Central

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

    2015-01-01

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

  8. Paleoseismicity of the North American-Caribbean plate boundary (Septentrional fault), Dominican Republic

    USGS Publications Warehouse

    Prentice, C.S.; Mann, P.; Taylor, F.W.; Burr, G.; Valastro, S.

    1993-01-01

    The Septentrional fault zone, the major North American-Caribbean plate-boundary fault in Hispaniola, is a likely source of large earthquakes in the Dominican Republic. An excavation into a Holocene alluvial fan deposited across the fault in the central Cibao Valley, Dominican Republic, provides evidence that it has been at least 430 yr and probably more than 740 yr since the last ground-rupturing earthquake along this segment of the fault. On the basis of these data and published estimates of the plate-tectonic slip rate, it is proposed that the Septentrional fault is a source of high seismic potential in the densely populated and rapidly developing Cibao Valley in the northern Dominican Republic. -Authors

  9. ARGES: an Expert System for Fault Diagnosis Within Space-Based ECLS Systems

    NASA Technical Reports Server (NTRS)

    Pachura, David W.; Suleiman, Salem A.; Mendler, Andrew P.

    1988-01-01

    ARGES (Atmospheric Revitalization Group Expert System) is a demonstration prototype expert system for fault management for the Solid Amine, Water Desorbed (SAWD) CO2 removal assembly, associated with the Environmental Control and Life Support (ECLS) System. ARGES monitors and reduces data in real time from either the SAWD controller or a simulation of the SAWD assembly. It can detect gradual degradations or predict failures. This allows graceful shutdown and scheduled maintenance, which reduces crew maintenance overhead. Status and fault information is presented in a user interface that simulates what would be seen by a crewperson. The user interface employs animated color graphics and an object oriented approach to provide detailed status information, fault identification, and explanation of reasoning in a rapidly assimulated manner. In addition, ARGES recommends possible courses of action for predicted and actual faults. ARGES is seen as a forerunner of AI-based fault management systems for manned space systems.

  10. Nonlinear Network Dynamics on Earthquake Fault Systems

    NASA Astrophysics Data System (ADS)

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

    2001-10-01

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

  11. Tutorial: Advanced fault tree applications using HARP

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  12. Fault Management Guiding Principles

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  13. Using Precision Gravity Survey To Locate Faults Within The Southern Mesilla Bolson, Rio Grande Rift.

    NASA Astrophysics Data System (ADS)

    Khatun, S.; Doser, D.; Imana, E.

    2003-12-01

    The southern Mesilla bolson of west Texas and southern New Mexico is a rapidly growing portion of the El Paso-Juarez metropolitan area. Faulting within the bolson is difficult to trace due to intensive urban and agricultural activities. Prior to channelization of the Rio Grande in the 1930's the river also frequently altered its course, rapidly depositing or eroding sediment within the bolson, also making the tracing of faults or offset surfaces difficult. We have used the precision gravity technique (digital precision gravity meter, station spacing of 60 m or less, elevation known to 30 cm or less) as an inexpensive method to map possible locations of faults within the bolson. We analyze the gravity data using 3-D modeling techniques that can account for known geology and topography, which are then subtracted from the observed gravity data. The residual gravity map is then examined for sharp gradients and bends in gravity contours that may indicate the presence of faults. Once suspected faults are identified we have conducted follow-up geophysical surveys (DC resistivity sounding, spectral analysis of surface waves) over the structures to determine if grain size or sediment compaction changes (often indicative of faults) are associated with the gravity anomalies. Water well logs have also aided in our interpretations. Our results suggest there are at least 3 faults within the bolson that parallel the range bounding fault that separates the eastern bolson from the western edge of the Franklin Mountains. If these faults are currently seismogenic, they represent a significant hazard to the urban areas located on the thick (1500 m), water saturated sediments of the bolson. We feel the precision gravity technique could serve as a useful reconnaissance tool to help identify faults in other regions where urbanization or other factors limit surface exposure of recent geologic processes.

  14. Rapid Prototyping

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Javelin, a Lone Peak Engineering Inc. Company has introduced the SteamRoller(TM) System as a commercial product. The system was designed by Javelin during a Phase II NASA funded small commercial product. The purpose of the invention was to allow automated-feed of flexible ceramic tapes to the Laminated Object Manufacturing rapid prototyping equipment. The ceramic material that Javelin was working with during the Phase II project is silicon nitride. This engineered ceramic material is of interest for space-based component.

  15. Coseismic paleomagnetic signal in fault pseudotachylytes?

    NASA Astrophysics Data System (ADS)

    Ferre, E.; Geissman, J. W.; Zechmeister, M. S.

    2012-04-01

    The 59 Ma-old fault-related pseudotachylytes of the Peninsular Ranges of California have been investigated from the microstructural and magnetic point of view. These veins have a 30-fold increase in magnetic susceptibility compared to their tonalitic host-rock. The increase results from the breakdown of mafic silicates during frictional melting and subsequent formation of abundant fine grained magnetite grains. Upon rapid cooling of the pseudotachylyte melt in the Earth's magnetic field the rocks acquire a strong thermoremanent magnetization. In addition to this dominant process some samples exhibit a "lightning-induced" remanent magnetization acquired during seismic slip in the presence of a high magnetic field. This unusual remanence component is anomalous in direction and tends to be at high angle to the pseudotachylyte vein plane. We propose that the coseismic lightning-induced magnetization is caused by electrical currents possibly similar to those responsible for earthquake lightnings.

  16. Faulting processes at high fluid pressures: An example of fault valve behavior from the Wattle Gully Fault, Victoria, Australia

    NASA Astrophysics Data System (ADS)

    Cox, Stephen F.

    1995-07-01

    The internal structures of the Wattle Gully Fault provide insights about the mechanics and dynamics of fault systems exhibiting fault valve behavior in high fluid pressure regimes. This small, high-angle reverse fault zone developed at temperatures near 300°C in the upper crust, late during mid-Devonian regional crustal shortening in central Victoria, Australia. The Wattle Gully Fault forms part of a network of faults that focused upward migration of fluids generated by metamorphism and devolatilisation at deeper crustal levels. The fault has a length of around 800 m and a maximum displacement of 50 m and was oriented at 60° to 80° to the maximum principal stress during faulting. The structure was therefore severely misoriented for frictional reactivation. This factor, together with the widespread development of steeply dipping fault fill quartz veins and associated subhorizontal extension veins within the fault zone, indicates that faulting occurred at low shear stresses and in a near-lithostatic fluid pressure regime. The internal structures of these veins, and overprinting relationships between veins and faults, indicate that vein development was intimately associated with faulting and involved numerous episodes of fault dilatation and hydrothermal sealing and slip, together with repeated hydraulic extension fracturing adjacent to slip surfaces. The geometries, distribution and internal structures of veins in the Wattle Gully Fault Zone are related to variations in shear stress, fluid pressure, and near-field principal stress orientations during faulting. Vein opening is interpreted to have been controlled by repeated fluid pressure fluctuations associated with cyclic, deformation-induced changes in fault permeability during fault valve behavior. Rates of recovery of shear stress and fluid pressure after rupture events are interpreted to be important factors controlling time dependence of fault shear strength and slip recurrence. Fluctuations in shear stress and transient rotations of near-field principal Stresses, indicated by vein geometries, are interpreted to indicate at least local near-total relief of shear stress during some rupture events. Fault valve behavior has important effects on the dynamics of fluid migration around active faults that are sites of focused fluid migration. In particular, fault valve action is expected to lead to distinctly different fluid migration patterns adjacent to faults before, and immediately after, rupture. These fluid migration patterns have important differences with those predicted by models for dilatancy-diffusion effects and for poroelastic responses around reverse faults.

  17. Software reliability through fault-avoidance and fault-tolerance

    NASA Technical Reports Server (NTRS)

    Vouk, Mladen A.; Mcallister, David F.

    1991-01-01

    Twenty independently developed but functionally equivalent software versions were used to investigate and compare empirically some properties of N-version programming, Recovery Block, and Consensus Recovery Block, using the majority and consensus voting algorithms. This was also compared with another hybrid fault-tolerant scheme called Acceptance Voting, using dynamic versions of consensus and majority voting. Consensus voting provides adaptation of the voting strategy to varying component reliability, failure correlation, and output space characteristics. Since failure correlation among versions effectively reduces the cardinality of the space in which the voter make decisions, consensus voting is usually preferable to simple majority voting in any fault-tolerant system. When versions have considerably different reliabilities, the version with the best reliability will perform better than any of the fault-tolerant techniques.

  18. Detection and diagnosis of bearing and cutting tool faults using hidden Markov models

    NASA Astrophysics Data System (ADS)

    Boutros, Tony; Liang, Ming

    2011-08-01

    Over the last few decades, the research for new fault detection and diagnosis techniques in machining processes and rotating machinery has attracted increasing interest worldwide. This development was mainly stimulated by the rapid advance in industrial technologies and the increase in complexity of machining and machinery systems. In this study, the discrete hidden Markov model (HMM) is applied to detect and diagnose mechanical faults. The technique is tested and validated successfully using two scenarios: tool wear/fracture and bearing faults. In the first case the model correctly detected the state of the tool (i.e., sharp, worn, or broken) whereas in the second application, the model classified the severity of the fault seeded in two different engine bearings. The success rate obtained in our tests for fault severity classification was above 95%. In addition to the fault severity, a location index was developed to determine the fault location. This index has been applied to determine the location (inner race, ball, or outer race) of a bearing fault with an average success rate of 96%. The training time required to develop the HMMs was less than 5 s in both the monitoring cases.

  19. Quaternary faults of west Texas

    SciTech Connect

    Collins, E.W.; Raney, J.A. . Bureau of Economic Geology)

    1993-04-01

    North- and northwest-striking intermontane basins and associated normal faults in West Texas and adjacent Chihuahua, Mexico, formed in response to Basin and Range tectonism that began about 24 Ma ago. Data on the precise ages of faulted and unfaulted Quaternary deposits are sparse. However, age estimates made on the basis of field stratigraphic relationships and the degree of calcic soil development have helped determine that many of the faults that bound the basin margins ruptured since the middle Pleistocene and that some faults probably ruptured during the Holocene. Average recurrence intervals between surface ruptures since the middle Pleistocene appear to be relatively long, about 10,000 to 100,000 yr. Maximum throw during single rupture events have been between 1 and 3 m. Historic seismicity in West Texas is low compared to seismicity in many parts of the Basin and Range province. The largest historic earthquake, the 1931 Valentine earthquake in Ryan Flat/Lobo Valley, had a magnitude of 6.4 and no reported surface rupture. The most active Quaternary faults occur within the 120-km-long Hueco Bolson, the 70-km-long Red Light Bolson, and the > 200-km-long Salt Basins/Wild Horse Flat/Lobo Valley/Ryan Flat.

  20. PC-based fault finder

    SciTech Connect

    Bengiamin, N.N. ); Jensen, C.A. . Electrical Engineering Dept. Otter Tail Power Co., Fergus Falls, MN . System Protection Group); McMahon, H. )

    1993-07-01

    Electric utilities are continually pressed to stay competitive while meeting the increasing demand of today's sophisticated customer. Advances in electron equipment and the improved array of electric driven devices are setting new standards for improved reliability and quality of service. Besides the specifications on voltage and frequency regulation and the permitted harmonic content, to name a few, the number and duration of service interruptions have a dramatic direct effect on the customer. Accurate fault locating reduces transmission line patrolling and is of particular significance in repairing long lines in rough terrain. Shortened outage times, reduced equipment degrading and stress on the system, fast restored service, and improved revenue are immediate outcomes of fast fault locating which insure minimum loss of system security. This article focuses on a PC-based (DOS) computer program that has unique features for identifying the type of fault and its location on overhead transmission/distribution lines. Balanced and unbalanced faults are identified and located accurately while accounting for changes in conductor sizes and network configuration. The presented concepts and methodologies have been spurred by Otter Tail Power's need for an accurate fault locating scheme to accommodate multiple feeders with mixed lone configurations. A case study based on a section of the Otter Tail network is presented to illustrate the features and capabilities of the developed software.

  1. Monitoring fault zone environments with correlations of earthquake waveforms

    NASA Astrophysics Data System (ADS)

    Roux, Philippe; Ben-Zion, Yehuda

    2014-02-01

    We develop a new technique for monitoring temporal changes in fault zone environments based on cross-correlation of earthquake waveforms recorded by pairs of stations. The method is applied to waveforms of 10 000 earthquakes observed during 100 d around the 1999 M 7.1 Duzce mainshock by a station located in the core damage zone of the North Anatolian Fault and a nearby station. To overcome clock problems, the correlation functions are realigned on a dominant peak. Consequently, the analysis focuses on measurements of coherency rather than traveltimes, and is associated with correlation coefficient of groups of events with a reference wavelet. Examination of coherency in different frequency bands reveals clear changes at a narrow band centred around 0.8 Hz. The results show a rapid drop of 1-2 per cent of the coherency at the time of the Duzce event followed by gradual recovery with several prominent oscillations over 4 d. The observed changes likely reflect evolution of permeability and fluid motion in the core damage zone of the North Anatolian Fault. Compared to noise correlation processing, our analysis of earthquake waveform correlation (i) benefits from high level of coherence with short duration recorded signals, (ii) has considerably finer temporal sampling of fault dynamics after mainshocks than is possible with noise correlation, (iii) uses the coherence level to track property variations, which may be more robust than traveltime fluctuations in the coda of noise correlations. Studies utilizing both earthquake and noise waveforms at multiple pairs of stations across fault damage zones can improve significantly the understanding of fault zone processes.

  2. Faulted archaeological relics at Hierapolis (Pamukkale), Turkey

    NASA Astrophysics Data System (ADS)

    Hancock, P. L.; Altunel, E.

    1997-09-01

    The former Roman city of Hierapolis (modern Pamukkale), within the Byk Menderes valley, contains an abundance of faulted architectural relics related to damaging earthquakes that have occurred since at least 60 A.D. Faulted relics include: (1) a Roman fresh-water channel; (2) a mid-Roman relief carved into a fault plane; (3) Roman and Byzantine walls offset across the Hierapolis normal fault zone; (4) the walls of a late Byzantine fort offset more than once across a fissure/fault; and (5) numerous displaced wall-like Roman and post-Roman petrified water channels. In addition to these faulted relics, numerous monuments display tilted and toppled walls; maximum damage generally being adjacent to the Hierapolis fault zone which passes through the centre of the city. Many relics are also partly covered by faulting-related travertine deposits. Analysis of the faulted relics indicates: (1) Hierapolis and its immediate surroundings are cut by two active normal fault zones; (2) the NNW-trending Hierapolis fault zone, formerly thought to be a sinistral strike-slip fault, is a small normal fault zone; (3) there has been about 1.5 m of normal slip on the Pamukkale range-front fault since mid-Roman times; (4) an opening direction across the weakly expressed Hierapolis fault zone can be inferred by matching formerly contiguous piercing points on the relic that are now on either side of the fault trace; (5) where a fault passes through a narrow rigid architectural relic, its trace is generally refracted so that it is oriented at roughly right angles to the long axis of the relic; and (6) some major dilated cracks cutting relics reflect the locations of underlying faults.

  3. Transient Faults in Computer Systems

    NASA Technical Reports Server (NTRS)

    Masson, Gerald M.

    1993-01-01

    A powerful technique particularly appropriate for the detection of errors caused by transient faults in computer systems was developed. The technique can be implemented in either software or hardware; the research conducted thus far primarily considered software implementations. The error detection technique developed has the distinct advantage of having provably complete coverage of all errors caused by transient faults that affect the output produced by the execution of a program. In other words, the technique does not have to be tuned to a particular error model to enhance error coverage. Also, the correctness of the technique can be formally verified. The technique uses time and software redundancy. The foundation for an effective, low-overhead, software-based certification trail approach to real-time error detection resulting from transient fault phenomena was developed.

  4. Intelligent fault-tolerant controllers

    NASA Technical Reports Server (NTRS)

    Huang, Chien Y.

    1987-01-01

    A system with fault tolerant controls is one that can detect, isolate, and estimate failures and perform necessary control reconfiguration based on this new information. Artificial intelligence (AI) is concerned with semantic processing, and it has evolved to include the topics of expert systems and machine learning. This research represents an attempt to apply AI to fault tolerant controls, hence, the name intelligent fault tolerant control (IFTC). A generic solution to the problem is sought, providing a system based on logic in addition to analytical tools, and offering machine learning capabilities. The advantages are that redundant system specific algorithms are no longer needed, that reasonableness is used to quickly choose the correct control strategy, and that the system can adapt to new situations by learning about its effects on system dynamics.

  5. Faulting in porous carbonate grainstones

    NASA Astrophysics Data System (ADS)

    Tondi, Emanuele; Agosta, Fabrizio

    2010-05-01

    In the recent past, a new faulting mechanism has been documented within porous carbonate grainstones. This mechanism is due to strain localization into narrow tabular bands characterized by both volumetric and shear strain; for this reason, these features are named compactive shear bands. In the field, compactive shear bands are easily recognizable because they are lightly coloured with respect to the parent rock, and/or show a positive relief because of their increased resistance to weathering. Both characteristics, light colours and positive relief, are a consequence of the compaction processes that characterize these bands, which are the simplest structure element that form within porous carbonate grainstones. With ongoing deformation, the single compactive shear bands, which solve only a few mm of displacement, may evolve into zone of compactive shear bands and, finally, into well-developed faults characterized by slip surfaces and fault rocks. Field analysis conducted in key areas of Italy allow us to documented different modalities of interaction and linkage among the compactive shear bands: (i) a simple divergence of two different compactive shear bands from an original one, (ii) extensional and contractional jogs formed by two continuous, interacting compactive shear bands, and (iii) eye structures formed by collinear interacting compactive shear bands, which have been already described for deformation bands in sandstones. The last two types of interaction may localize the formation of compaction bands, which are characterized by pronounced component of compaction and negligible components of shearing, and/or pressure solution seams. All the aforementioned types of interaction and linkage could happen at any deformation stage, single bands, zone of bands or well developed faults. The transition from one deformation process to another, which is likely to be controlled by the changes in the material properties, is recorded by different ratios and distributions of the fault dimensional attributes. The results of field analysis are consistent with length (L), displacement (D) and thickness (T) of single compactive shear bands clustering around given values, peculiar to the individual lithologies, and does not point out to any scale relationship among these parameters. On the contrary, in zones of shear bands and well-developed faults the D values are maximum in the central portion of individual elements. Differently from what characterize the well-developed faults, in which the slip increments are solved along the main slip surfaces, within zones of compactive shear bands the displacement varies according to the number of individual single bands, so that an increased displacement is related to an higher number of bands. As a consequence, the T-D plot concerning zones of compactive shear bands and well-developed faults show two different populations, which suggest that well-developed faults are much efficient to resolve displacement, with respect the zone of shear bands, because they include sharp slip surfaces. The petrographical and petrophysical properties of the tectonic features described above, which have been assessed by mean of detailed laboratory analyses, are consistent with the single compactive shear bands and zones of shear bands behaving as seals for underground fluid flow with respect to the host rock. These features, strongly present within the fault damage zones of well-developed faults, may compartmentalize the fluid flow in faulted carbonate reservoirs.

  6. Fault Diagnosis for the Heat Exchanger of the Aircraft Environmental Control System Based on the Strong Tracking Filter

    PubMed Central

    Ma, Jian; Lu, Chen; Liu, Hongmei

    2015-01-01

    The aircraft environmental control system (ECS) is a critical aircraft system, which provides the appropriate environmental conditions to ensure the safe transport of air passengers and equipment. The functionality and reliability of ECS have received increasing attention in recent years. The heat exchanger is a particularly significant component of the ECS, because its failure decreases the system’s efficiency, which can lead to catastrophic consequences. Fault diagnosis of the heat exchanger is necessary to prevent risks. However, two problems hinder the implementation of the heat exchanger fault diagnosis in practice. First, the actual measured parameter of the heat exchanger cannot effectively reflect the fault occurrence, whereas the heat exchanger faults are usually depicted by utilizing the corresponding fault-related state parameters that cannot be measured directly. Second, both the traditional Extended Kalman Filter (EKF) and the EKF-based Double Model Filter have certain disadvantages, such as sensitivity to modeling errors and difficulties in selection of initialization values. To solve the aforementioned problems, this paper presents a fault-related parameter adaptive estimation method based on strong tracking filter (STF) and Modified Bayes classification algorithm for fault detection and failure mode classification of the heat exchanger, respectively. Heat exchanger fault simulation is conducted to generate fault data, through which the proposed methods are validated. The results demonstrate that the proposed methods are capable of providing accurate, stable, and rapid fault diagnosis of the heat exchanger. PMID:25823010

  7. Fault diagnosis for the heat exchanger of the aircraft environmental control system based on the strong tracking filter.

    PubMed

    Ma, Jian; Lu, Chen; Liu, Hongmei

    2015-01-01

    The aircraft environmental control system (ECS) is a critical aircraft system, which provides the appropriate environmental conditions to ensure the safe transport of air passengers and equipment. The functionality and reliability of ECS have received increasing attention in recent years. The heat exchanger is a particularly significant component of the ECS, because its failure decreases the system's efficiency, which can lead to catastrophic consequences. Fault diagnosis of the heat exchanger is necessary to prevent risks. However, two problems hinder the implementation of the heat exchanger fault diagnosis in practice. First, the actual measured parameter of the heat exchanger cannot effectively reflect the fault occurrence, whereas the heat exchanger faults are usually depicted by utilizing the corresponding fault-related state parameters that cannot be measured directly. Second, both the traditional Extended Kalman Filter (EKF) and the EKF-based Double Model Filter have certain disadvantages, such as sensitivity to modeling errors and difficulties in selection of initialization values. To solve the aforementioned problems, this paper presents a fault-related parameter adaptive estimation method based on strong tracking filter (STF) and Modified Bayes classification algorithm for fault detection and failure mode classification of the heat exchanger, respectively. Heat exchanger fault simulation is conducted to generate fault data, through which the proposed methods are validated. The results demonstrate that the proposed methods are capable of providing accurate, stable, and rapid fault diagnosis of the heat exchanger. PMID:25823010

  8. InSAR measurements around active faults: creeping Philippine Fault and un-creeping Alpine Fault

    NASA Astrophysics Data System (ADS)

    Fukushima, Y.

    2013-12-01

    Recently, interferometric synthetic aperture radar (InSAR) time-series analyses have been frequently applied to measure the time-series of small and quasi-steady displacements in wide areas. Large efforts in the methodological developments have been made to pursue higher temporal and spatial resolutions by using frequently acquired SAR images and detecting more pixels that exhibit phase stability. While such a high resolution is indispensable for tracking displacements of man-made and other small-scale structures, it is not necessarily needed and can be unnecessarily computer-intensive for measuring the crustal deformation associated with active faults and volcanic activities. I apply a simple and efficient method to measure the deformation around the Alpine Fault in the South Island of New Zealand, and the Philippine Fault in the Leyte Island. I use a small-baseline subset (SBAS) analysis approach (Berardino, et al., 2002). Generally, the more we average the pixel values, the more coherent the signals are. Considering that, for the deformation around active faults, the spatial resolution can be as coarse as a few hundred meters, we can severely 'multi-look' the interferograms. The two applied cases in this study benefited from this approach; I could obtain the mean velocity maps on practically the entire area without discarding decorrelated areas. The signals could have been only partially obtained by standard persistent scatterer or single-look small-baseline approaches that are much more computer-intensive. In order to further increase the signal detection capability, it is sometimes effective to introduce a processing algorithm adapted to the signal of interest. In an InSAR time-series processing, one usually needs to set the reference point because interferograms are all relative measurements. It is difficult, however, to fix the reference point when one aims to measure long-wavelength deformation signals that span the whole analysis area. This problem can be solved by adding the displacement offset in each interferogram as a model parameter and solving the system of equations with the minimum norm condition. This way, the unknown offsets can be automatically determined. By applying this method to the ALOS/PALSAR data acquired over the Alpine Fault, I obtained the mean velocity map showing the right-lateral relative motion of the blocks north and south of the fault and the strain concentration (large velocity gradient) around the fault. The velocity gradient around the fault has along-fault variation, probably reflecting the variation in the fault locking depth. When one aims to detect fault creeps, i.e., displacement discontinuity in space, one can additionally introduce additional parameters to describe the phase ramps in the interferograms and solve the system of equations again with the minimum norm condition. Then, the displacement discontinuity appears more clearly in the result at the cost of suppressing long-wavelength displacements. By applying this method to the ALOS/PALSAR data acquired over the Philippine Fault in Leyte Island, I obtained the mean velocity map showing fault creep at least in the northern and central parts of Leyte at a rate of around 10 mm/year.

  9. Repeated Seismic Slips Recorded in Fluidized ultracataclastic Veins within Shallow Seismogenic Fault Zones

    NASA Astrophysics Data System (ADS)

    Lin, A.

    2014-12-01

    It is well known that direct evidence of earthquakes within fault zones is limited to the presence of pseudotachylyte. In addition to pseudotachylyte, previous studies have shown that the meso- and microstructural features of cataclastic veins that lack the primary cohesion of the host rocks, including crush-origin pseudotachylyte, fault breccia, may represent primary evidence of brittle deformation caused by recurrent seismic slip within shallow seismogenic fault zones (e.g., Lin, 1996, 2008). In this presentation, we report on the structural mode of typical ultracataclastic veins including pseudotachylyte and fault gouge veins that formed repeatedly as simple veins and complex networks at shallow depth within two main active fault zones along the Arima-Takatsuki Tectonic Line (ATTL) and the Itoigawa-Shizuoka Tectonic Line (ISTL), Japan. Multistage veinlet cataclastic rocks, composed of aphanitic veins typical of pseudotachylyte and unconsolidated fault gouge, breccias, as complex networks along the main active fault zones. Early veins are generally fractured and overprinted by younger veins, indicating that vein-forming events occurred repeatedly within the same fault shear zone. Microstructurally, both the pseudotachylyte and fault gouge veins are characterized by a superfine- to fine-grained matrix and angular-subangular fragments ranging in size from submicron scale to several centimeters. Based on the meso- and microstructural features of veinlet ultracataclastic rocks and the results of powder X-ray diffraction analyses, we conclude that (i) the pseudotachylyte veins were generated mainly by crushing rather than melting at shallow fault zones, and (ii) multistage veinlet fault gouge and pseudotachylyte formed repeatedly within the fault-fracture zone via the rapid fluidization and injection of superfine- to fine-grained materials derived from the host rocks during large-magnitude earthquakes that occurred along the active fault zones within the ATTL and ISTL. Our results show that the fluidized ultracataclastic veins record paleoseismic faulting events that occurred at shallow seismogenic fault zones; consequently, these features are a type of earthquake fossil, as is melt-origin pseudotachylyte.

  10. Quantifying Morphologic Changes in a Low Gradient River Crossing Southeast Louisiana Fault Zones

    NASA Astrophysics Data System (ADS)

    Fischer, G.; Gasparini, N. M.; Dawers, N. H.

    2011-12-01

    This study investigates the signature of faulting in low gradient, alluvial rivers crossing the Baton Rouge fault zone (BRFZ) and Denham Springs-Scotlandville fault zone (DSSFZ), which encompass a set of East-West striking normal faults in southeast Louisiana. These faults exhibit surface expressions associated with up to a few meters of vertical displacement of Late Pleistocene sediments, but little is known about their activity during the Holocene. Our study aims to quantify geomorphic changes in a number of rivers that cross these fault zones and to use these changes to gain insight into the history of faulting in the region. We hypothesize that fault movement will be evident in patterns of river sinuosity, slope, and width to depth ratio. We focus on four subparallel channels of various discharges that cross either or both the BRFZ and the DSSFZ. Information on local fault scarp heights and channel reaches are extracted by GIS analysis of the LA LiDAR 5 m DEM, as well as flow modeling using the HEC-RAS software program. On the Tickfaw River, we conducted field surveys using differential GPS to record contemporary water surface slopes and channel location. Historic channel features on the Tickfaw are characterized using a series of aerial photographs dating back to 1952. Over the past 50 years, the Tickfaw River has shortened its course through the study area significantly (~4.9%) by means of meander cutoffs. Since 1952, sinuosity (P) has decreased in all of the Tickfaw channel reaches that cross fault segments. Currently, the sinuosity is extremely low (average P = 1.14) where the river crosses the DSSFZ and slightly higher where the river crosses the BRFZ (average P = 1.9). We use the LiDAR data to quantify offset on the faults that the river crosses. These values will be compared with the average lateral migration rate of the river in order to better understand the time scales over which both processes operate. If the faults appear to have little morphologic impact on the river, it is likely that that fluvial migration rates are rapid enough to erase any signature of the accumulated throw from the faults. With continued analysis, our goal is to develop a reliable method for using alluvial rivers to help unravel the history of fault systems in low gradient landscapes, with possible applications for detecting regions vulnerable to fault-related subsidence.

  11. Update: San Andreas Fault experiment

    NASA Technical Reports Server (NTRS)

    Christodoulidis, D. C.; Smith, D. E.

    1984-01-01

    Satellite laser ranging techniques are used to monitor the broad motion of the tectonic plates comprising the San Andreas Fault System. The San Andreas Fault Experiment, (SAFE), has progressed through the upgrades made to laser system hardware and an improvement in the modeling capabilities of the spaceborne laser targets. Of special note is the launch of the Laser Geodynamic Satellite, LAGEOS spacecraft, NASA's only completely dedicated laser satellite in 1976. The results of plate motion projected into this 896 km measured line over the past eleven years are summarized and intercompared.

  12. Automated distribution fault locating system

    SciTech Connect

    Hager, G.E.; Medicine Bear, R.N.; Baum, A.S.

    1996-05-01

    An automated fault locating system (FLS) was designed and implemented for the Colorado River Agency (CRA) 12.5/7.2-kV distribution system. This FLS was integrated into the supervisory control and data acquisition (SCADA) system which was installed at a hydropower plant. This FLS offers several benefits to the CRA distribution system. These benefits include reduced outage time, help in locating momentary faults, enhanced safety to the line crews, provide notification of an outage without receiving calls from the consumer, and decreased overtime.

  13. Matching pursuit of an adaptive impulse dictionary for bearing fault diagnosis

    NASA Astrophysics Data System (ADS)

    Cui, Lingli; Wang, Jing; Lee, Seungchul

    2014-05-01

    The sparse decomposition based on matching pursuit is an adaptive sparse expression of the signals. An adaptive matching pursuit algorithm that uses an impulse dictionary is introduced in this article for rolling bearing vibration signal processing and fault diagnosis. First, a new dictionary model is established according to the characteristics and mechanism of rolling bearing faults. The new model incorporates the rotational speed of the bearing, the dimensions of the bearing and the bearing fault status, among other parameters. The model can simulate the impulse experienced by the bearing at different bearing fault levels. A simulation experiment suggests that a new impulse dictionary used in a matching pursuit algorithm combined with a genetic algorithm has a more accurate effect on bearing fault diagnosis than using a traditional impulse dictionary. However, those two methods have some weak points, namely, poor stability, rapidity and controllability. Each key parameter in the dictionary model and its influence on the analysis results are systematically studied, and the impulse location is determined as the primary model parameter. The adaptive impulse dictionary is established by changing characteristic parameters progressively. The dictionary built by this method has a lower redundancy and a higher relevance between each dictionary atom and the analyzed vibration signal. The matching pursuit algorithm of an adaptive impulse dictionary is adopted to analyze the simulated signals. The results indicate that the characteristic fault components could be accurately extracted from the noisy simulation fault signals by this algorithm, and the result exhibited a higher efficiency in addition to an improved stability, rapidity and controllability when compared with a matching pursuit approach that was based on a genetic algorithm. We experimentally analyze the early-stage fault signals and composite fault signals of the bearing. The results further demonstrate the effectiveness and superiority of the matching pursuit algorithm that uses the adaptive impulse dictionary. Finally, this algorithm is applied to the analysis of engineering data, and good results are achieved.

  14. What can satellite geodesy tell us about fault zone mechanics and seismic hazard in the continents?

    NASA Astrophysics Data System (ADS)

    Wright, Tim

    2015-04-01

    Reliable assessment of hazard from short-term geodetic observations requires physical models that can explain any time-dependent surface deformation. In this lectures, I will review the observations, show models that are consistent with all the data, and discuss the implications for the mechanics of fault zones and the strength of the continental lithosphere. The last twenty years has seen a dramatic growth in our ability to measure surface deformation in fault zones using satellite geodesy. Collectively, these observations require any successful model to be capable of producing rapid postseismic deformation transients that decay with a 1/t dependency, and steady strain focussed in relatively narrow regions around the fault later in the cycle. I will show that these observations require (i) the lower crust outside of fault zones to have a viscosity greater than ~1020 Pa s, (ii) a region beneath the seismogenic upper crust that can respond rapidly to a stress perturbation. Rapid postseismic relaxation can occur through afterslip on a downward continuation of the fault, or by viscoelastic relaxation in a weak zone beneath the fault. If the relaxation is occurring viscoelastically, explaining the 1/t dependency requires a non-linear power-law relationship between stress and strain, and/or a viscosity that varies spatially due to temperature. It has been shown that such rheologies concentrate lower-crustal shear into narrow zones, a few kilometres wide. A model with narrow shear in the lower crust beneath major faults is also consistent with geological observations and results from a recent seismic experiment on the North Anatolian Fault conducted by the University of Leeds with Turkish partners at Kandilli Observatory and Sakarya University. I will conclude by discussing the implications of this synthesis for the use of satellite geodesy for seismic hazard assessment, the mechanics of continental deformation, and the strength of the continental lithosphere, and by speculating on the future of geodetic observations in the coming era of big data.

  15. Continuous creep measurements on the North Anatolian fault

    NASA Astrophysics Data System (ADS)

    Mencin, D.; Bilham, R. G.; Ozener, H.; Aktug, B.; Dogru, A.; Ergintav, S.; Cakir, Z.; Aytun, A.

    2014-12-01

    Surface creep was recognized as early as 1969 on the North Anatolian fault near Ismetpasa and continues to the present day at rates of the order of 5 mm/yr. Although subsurface creep is currently monitored using Insar and GPS, continuous creep measurements on the surface fault have been intermittent. In 2014 we installed a carbon-fiber rod creepmeter at Ismetpasa and a second creepmeter across the surface rupture of the 1999 Izmit earthquake, which is also known to be creeping at depth. The creepmeters have a resolution of 5 μm and a range of 2.2 m. Each creepmeter uses two sensors- a subsurface LVDT (resolution 5 μm range 10 mm) and an above-ground rotary Hall effect sensor (resolution 25 μm and range 2.2 m) and their data are transmitted via the Iridium satellite as 30 minute samples every 2 hours. The hybrid sensors on the creepmeters are similar to others currently operating on the Hayward, Calaveras, and San Andreas faults. Their ability to capture slow slip, coseismic rupture or afterslip has been tested in deployments on the rapidly creeping Jackson, Wyoming landslide (1-3 mm/day). Installed creepmeters will be a powerful tool to search the possibilities of the transient or episodic creep and they will be used to validate the results of on-going monthly InSAR and campaign GPS studies, along the north Anatolian fault.

  16. Heat flow and energetics of the San Andreas fault zone.

    USGS Publications Warehouse

    Lachenbruch, A.H.; Sass, J.H.

    1980-01-01

    Approximately 100 heat flow measurements in the San Andreas fault zone indicate 1) there is no evidence for local frictional heating of the main fault trace at any latitude over a 1000-km length from Cape Mendocino to San Bernardino, 2) average heat flow is high (ca.2 HFU, ca.80 mW m-2) throughout the 550-km segment of the Coast Ranges that encloses the San Andreas fault zone in central California; this broad anomaly falls off rapidly toward the Great Valley to the east, and over a 200-km distance toward the Mendocino Triple Junction to the northwest. As others have pointed out, a local conductive heat flow anomaly would be detectable unless the frictional resistance allocated to heat production on the main trace were less than 100 bars. Frictional work allocated to surface energy of new fractures is probably unimportant, and hydrologic convection is not likely to invalidate the conduction assumption, since the heat discharge by thermal springs near the fault is negligible. -Authors

  17. Active fault traces along Bhuj Fault and Katrol Hill Fault, and trenching survey at Wandhay, Kachchh, Gujarat, India

    NASA Astrophysics Data System (ADS)

    Morino, Michio; Malik, Javed N.; Mishra, Prashant; Bhuiyan, Chandrashekhar; Kaneko, Fumio

    2008-06-01

    Several new active fault traces were identified along Katrol Hill Fault (KHF). A new fault (named as Bhuj Fault, BF) that extends into the Bhuj Plain was also identified. These fault traces were identified based on satellite photo interpretation and field survey. Trenches were excavated to identify the paleoseismic events, pattern of faulting and the nature of deformation. New active fault traces were recognized about 1km north of the topographic boundary between the Katrol Hill and the plain area. The fault exposure along the left bank of Khari River with 10m wide shear zone in the Mesozoic rocks and showing displacement of the overlying Quaternary deposits is indicative of continued tectonic activity along the ancient fault. The E-W trending active fault traces along the KHF in the western part changes to NE-SW or ENE-WSW near Wandhay village. Trenching survey across a low scarp near Wandhay village reveals three major fault strands F1, F2, and F3. These fault strands displaced the older terrace deposits comprising Sand, Silt and Gravel units along with overlying younger deposits from units 1 to 5 made of gravel, sand and silt. Stratigraphic relationship indicates at least three large magnitude earthquakes along KHF during Late Holocene or recent historic past.

  18. Late Quaternary Deformation Along the Wairarapa Fault, North Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Schermer, E. R.; Little, T. A.

    2006-12-01

    The Wairarapa fault, one of the largest active faults in the hanging wall of the Hikurangi subduction margin, New Zealand, averaged 16m dextral slip during the M >8.1 1855 earthquake. Previous workers inferred that uplift of 2.7m at the coast, observed by a surveyor in 1855, occurred on the southern continuation of the Wairarapa fault, the Wharekauhau (WH) thrust. New mapping, stratigraphic, and paloseismologic results from the WH thrust suggest the pattern of surface rupture in 1855 and earlier earthquakes was significantly different than previously inferred, requiring a more complex model for seismic hazard and tectonic evolution of the region. Detailed mapping indicates that the coastal segment of the WH thrust did not rupture the surface in 1855. The thrust, a major range-bounding fault, emplaces Mesozoic graywacke over ~80-100 ka last- interglacial marine, and lacustrine rocks, and in part coeval to younger alluvial gravels. Fault activity is indicated by facies and thickness changes. This older sequence is tilted and overlapped unconformably by a silt layer and much less deformed alluvial fan gravels that range in age from >22ka to <9 ka. These younger gravels were deposited in a valley incised across the fault scarp, in-filled this topography, and show no evidence of syn-depositional deformation. New 14C ages record a period of fault inactivity from 14 - 9 ka (calib yrs BP). The abandoned, overlapping fan surface is slightly deformed across the fault (15 m of folding- related throw). We infer that the thrust has propagated eastward in the subsurface, uplifting the abandoned WH fault, an inference that is supported by the pattern of Holocene incision. The only recent faulting consists of subvertical en echelon segments that have undergone minor dip-slip and dextral slip. A trench excavated across the fault scarp in late Holocene gravels suggests that the only fault along the trace of the WH thrust that broke within 3 m of the surface in 1855 was a minor strike-slip fault splay. New14C ages are consistent with the most recent event occurring in 1855 and suggest one earlier event. The range-bounding trace of the WH thrust appears to have been abandoned in the Holocene, with deformation occuring both west and east of this fault. Thus southern end of the Wairarapa fault consists of at least three active structures: 1) A western oblique-slip fault (or fault zone) that has ruptured repeatedly in the Holocene, including 1855, uplifting the Rimutaka anticline and accommodating large-magnitude strike-slip. Details of the 1855 event are obscured by landsliding in the Rimutaka range but the uplift is recorded by a flight of beach ridges at Turakirae Head; 2) a middle strike-slip strand that in part coincides with the projected trace of the abandoned WH thrust: 3) an eastern blind thrust that initiated after 9 ka and that has an unknown rupture history. Uplift with respect to sea level on the middle and eastern strands of the WH fault zone totals ~1mm/yr over the last 125 ka, and is indistinguishable in rate from that measured along the main (strike- slip) part of the Wairarapa fault to the north. To the west of the WH fault, the crest of the Rimutaka anticline at the coast is uplifting at 3 times this rate, (McSaveny et al., in press). The relationship between this locally enhanced rate of coastal uplift at the southern end of the Wairarapa fault zone, and the WH fault is apparently complex and changing rapidly in time, but has important implications for understanding seismic hazard and tectonics of this part of the Hikurangi margin.

  19. Detection of faults and software reliability analysis

    NASA Technical Reports Server (NTRS)

    Knight, J. C.

    1987-01-01

    Specific topics briefly addressed include: the consistent comparison problem in N-version system; analytic models of comparison testing; fault tolerance through data diversity; and the relationship between failures caused by automatically seeded faults.

  20. Parametric Modeling and Fault Tolerant Control

    NASA Technical Reports Server (NTRS)

    Wu, N. Eva; Ju, Jianhong

    2000-01-01

    Fault tolerant control is considered for a nonlinear aircraft model expressed as a linear parameter-varying system. By proper parameterization of foreseeable faults, the linear parameter-varying system can include fault effects as additional varying parameters. A recently developed technique in fault effect parameter estimation allows us to assume that estimates of the fault effect parameters are available on-line. Reconfigurability is calculated for this model with respect to the loss of control effectiveness to assess the potentiality of the model to tolerate such losses prior to control design. The control design is carried out by applying a polytopic method to the aircraft model. An error bound on fault effect parameter estimation is provided, within which the Lyapunov stability of the closed-loop system is robust. Our simulation results show that as long as the fault parameter estimates are sufficiently accurate, the polytopic controller can provide satisfactory fault-tolerance.

  1. Seismology: Diary of a wimpy fault

    NASA Astrophysics Data System (ADS)

    Bürgmann, Roland

    2015-05-01

    Subduction zone faults can slip slowly, generating tremor. The varying correlation between tidal stresses and tremor occurring deep in the Cascadia subduction zone suggests that the fault is inherently weak, and gets weaker as it slips.

  2. A summary of the active fault investigation in the extension sea area of Kikugawa fault and the Nishiyama fault , N-S direction fault in south west Japan

    NASA Astrophysics Data System (ADS)

    Abe, S.

    2010-12-01

    In this study, we carried out two sets of active fault investigation by the request from Ministry of Education, Culture, Sports, Science and Technology in the sea area of the extension of Kikugawa fault and the Nishiyama fault. We want to clarify the five following matters about both active faults based on those results. (1)Fault continuity of the land and the sea. (2) The length of the active fault. (3) The division of the segment. (4) Activity characteristics. In this investigation, we carried out a digital single channel seismic reflection survey in the whole area of both active faults. In addition, a high-resolution multichannel seismic reflection survey was carried out to recognize the detailed structure of a shallow stratum. Furthermore, the sampling with the vibrocoring to get information of the sedimentation age was carried out. The reflection profile of both active faults was extremely clear. The characteristics of the lateral fault such as flower structure, the dispersion of the active fault were recognized. In addition, from analysis of the age of the stratum, it was recognized that the thickness of the sediment was extremely thin in Holocene epoch on the continental shelf in this sea area. It was confirmed that the Kikugawa fault extended to the offing than the existing results of research by a result of this investigation. In addition, the width of the active fault seems to become wide toward the offing while dispersing. At present, we think that we can divide Kikugawa fault into some segments based on the distribution form of the segment. About the Nishiyama fault, reflection profiles to show the existence of the active fault was acquired in the sea between Ooshima and Kyushu. From this result and topographical existing results of research in Ooshima, it is thought that Nishiyama fault and the Ooshima offing active fault are a series of structure. As for Ooshima offing active fault, the upheaval side changes, and a direction changes too. Therefore, we think that we can divide Nishiyama fault into some segments based on the distribution form of the segment like Kikugawa fault.About both active faults, the length of the active fault, segment division, the activity characteristics of each segment are examining now.

  3. Automatic fault diagnosis of a switching regulator

    NASA Astrophysics Data System (ADS)

    Nienhaus, H. A.; Palmer, D. E.

    This paper describes a microprocessor-based system for the automatic fault diagnosis of a switching regulator. It covers the system from a test philosophy to a working breadboard that correctly identifies single simulated faults in the switching regulator. In addition to open circuit, short circuit, and stuck at faults, the system is capable of diagnosing faults due to excessive leakage, drift in critical components, and system instability.

  4. A Thermal Technique of Fault Nucleation, Growth, and Slip

    NASA Astrophysics Data System (ADS)

    Garagash, D.; Germanovich, L. N.; Murdoch, L. C.; Martel, S. J.; Reches, Z.; Elsworth, D.; Onstott, T. C.

    2009-12-01

    Fractures and fluids influence virtually all mechanical processes in the crust, but many aspects of these processes remain poorly understood largely because of a lack of controlled field experiments at appropriate scale. We have developed an in-situ experimental approach to create carefully controlled faults at scale of ~10 meters using thermal techniques to modify in situ stresses to the point where the rock fails in shear. This approach extends experiments on fault nucleation and growth to length scales 2-3 orders of magnitude greater than are currently possible in the laboratory. The experiments could be done at depths where the modified in situ stresses are sufficient to drive faulting, obviating the need for unrealistically large loading frames. Such experiments require an access to large rock volumes in the deep subsurface in a controlled setting. The Deep Underground Science and Engineering Laboratory (DUSEL), which is a research facility planned to occupy the workings of the former Homestake gold mine in the northern Black Hills, South Dakota, presents an opportunity for accessing locations with vertical stresses as large as 60 MPa (down to 2400 m depth), which is sufficient to create faults. One of the most promising methods for manipulating stresses to create faults that we have evaluated involves drilling two parallel planar arrays of boreholes and circulating cold fluid (e.g., liquid nitrogen) to chill the region in the vicinity of the boreholes. Cooling a relatively small region around each borehole causes the rock to contract, reducing the normal compressive stress throughout much larger region between the arrays of boreholes. This scheme was evaluated using both scaling analysis and a finite element code. Our results show that if the boreholes are spaced by ~1 m, in several days to weeks, the normal compressive stress can be reduced by 10 MPa or more, and it is even possible to create net tension between the borehole arrays. According to the Mohr-Coulomb strength criterion with standard Byerlee parameters, a fault will initiate before the net tension occurs. After a new fault is created, hot fluid can be injected into the boreholes to increase the temperature and reverse the direction of fault slip. This process can be repeated to study the formation of gouge, and how the properties of gouge control fault slip and associated seismicity. Instrumenting the site with arrays of geophones, tiltmeters, strain gauges, and displacement transducers as well as back mining - an opportunity provided by the DUSEL project - can reveal details of the fault geometry and gouge. We also expect to find small faults (with cm-scale displacement) during construction of DUSEL drifts. The same thermal technique can be used to induce slip on one of them and compare the “man-made” and natural gouges. The thermal technique appears to be a relatively simple way to rapidly change the stress field and either create slip on existing fractures or create new faults at scales up to 10 m or more.

  5. MOS integrated circuit fault modeling

    NASA Technical Reports Server (NTRS)

    Sievers, M.

    1985-01-01

    Three digital simulation techniques for MOS integrated circuit faults were examined. These techniques embody a hierarchy of complexity bracketing the range of simulation levels. The digital approaches are: transistor-level, connector-switch-attenuator level, and gate level. The advantages and disadvantages are discussed. Failure characteristics are also described.

  6. Cell boundary fault detection system

    SciTech Connect

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

    2011-04-19

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

  7. Geometric Analyses of Rotational Faults.

    ERIC Educational Resources Information Center

    Schwert, Donald Peters; Peck, Wesley David

    1986-01-01

    Describes the use of analysis of rotational faults in undergraduate structural geology laboratories to provide students with applications of both orthographic and stereographic techniques. A demonstration problem is described, and an orthographic/stereographic solution and a reproducible black model demonstration pattern are provided. (TW)

  8. 20 CFR 255.11 - Fault.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 1 2011-04-01 2011-04-01 false Fault. 255.11 Section 255.11 Employees... § 255.11 Fault. (a) Before recovery of an overpayment may be waived, it must be determined that the overpaid individual was without fault in causing the overpayment. If recovery is sought from other than...

  9. 5 CFR 831.1402 - Fault.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 5 Administrative Personnel 2 2011-01-01 2011-01-01 false Fault. 831.1402 Section 831.1402...) RETIREMENT Standards for Waiver of Overpayments § 831.1402 Fault. A recipient of an overpayment is without fault if he/she performed no act of commission or omission which resulted in the overpayment. The...

  10. 20 CFR 255.11 - Fault.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 1 2010-04-01 2010-04-01 false Fault. 255.11 Section 255.11 Employees... § 255.11 Fault. (a) Before recovery of an overpayment may be waived, it must be determined that the overpaid individual was without fault in causing the overpayment. If recovery is sought from other than...

  11. 20 CFR 255.11 - Fault.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 20 Employees' Benefits 1 2013-04-01 2012-04-01 true Fault. 255.11 Section 255.11 Employees... § 255.11 Fault. (a) Before recovery of an overpayment may be waived, it must be determined that the overpaid individual was without fault in causing the overpayment. If recovery is sought from other than...

  12. High temperature superconducting fault current limiter

    DOEpatents

    Hull, J.R.

    1997-02-04

    A fault current limiter for an electrical circuit is disclosed. The fault current limiter includes a high temperature superconductor in the electrical circuit. The high temperature superconductor is cooled below its critical temperature to maintain the superconducting electrical properties during operation as the fault current limiter. 15 figs.

  13. 5 CFR 831.1402 - Fault.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 5 Administrative Personnel 2 2014-01-01 2014-01-01 false Fault. 831.1402 Section 831.1402...) RETIREMENT Standards for Waiver of Overpayments § 831.1402 Fault. A recipient of an overpayment is without fault if he/she performed no act of commission or omission which resulted in the overpayment. The...

  14. 5 CFR 845.302 - Fault.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 5 Administrative Personnel 2 2013-01-01 2013-01-01 false Fault. 845.302 Section 845.302... EMPLOYEES RETIREMENT SYSTEM-DEBT COLLECTION Standards for Waiver of Overpayments § 845.302 Fault. A recipient of an overpayment is without fault if he or she performed no act of commission or omission...

  15. 5 CFR 845.302 - Fault.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 5 Administrative Personnel 2 2011-01-01 2011-01-01 false Fault. 845.302 Section 845.302... EMPLOYEES RETIREMENT SYSTEM-DEBT COLLECTION Standards for Waiver of Overpayments § 845.302 Fault. A recipient of an overpayment is without fault if he or she performed no act of commission or omission...

  16. 20 CFR 255.11 - Fault.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 1 2014-04-01 2012-04-01 true Fault. 255.11 Section 255.11 Employees... § 255.11 Fault. (a) Before recovery of an overpayment may be waived, it must be determined that the overpaid individual was without fault in causing the overpayment. If recovery is sought from other than...

  17. 5 CFR 845.302 - Fault.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 5 Administrative Personnel 2 2010-01-01 2010-01-01 false Fault. 845.302 Section 845.302... EMPLOYEES RETIREMENT SYSTEM-DEBT COLLECTION Standards for Waiver of Overpayments § 845.302 Fault. A recipient of an overpayment is without fault if he or she performed no act of commission or omission...

  18. 5 CFR 845.302 - Fault.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 5 Administrative Personnel 2 2014-01-01 2014-01-01 false Fault. 845.302 Section 845.302... EMPLOYEES RETIREMENT SYSTEM-DEBT COLLECTION Standards for Waiver of Overpayments § 845.302 Fault. A recipient of an overpayment is without fault if he or she performed no act of commission or omission...

  19. 5 CFR 831.1402 - Fault.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 5 Administrative Personnel 2 2013-01-01 2013-01-01 false Fault. 831.1402 Section 831.1402...) RETIREMENT Standards for Waiver of Overpayments § 831.1402 Fault. A recipient of an overpayment is without fault if he/she performed no act of commission or omission which resulted in the overpayment. The...

  20. 5 CFR 831.1402 - Fault.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 5 Administrative Personnel 2 2010-01-01 2010-01-01 false Fault. 831.1402 Section 831.1402...) RETIREMENT Standards for Waiver of Overpayments § 831.1402 Fault. A recipient of an overpayment is without fault if he/she performed no act of commission or omission which resulted in the overpayment. The...

  1. 20 CFR 255.11 - Fault.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 1 2012-04-01 2012-04-01 false Fault. 255.11 Section 255.11 Employees... § 255.11 Fault. (a) Before recovery of an overpayment may be waived, it must be determined that the overpaid individual was without fault in causing the overpayment. If recovery is sought from other than...

  2. 5 CFR 845.302 - Fault.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 5 Administrative Personnel 2 2012-01-01 2012-01-01 false Fault. 845.302 Section 845.302... EMPLOYEES RETIREMENT SYSTEM-DEBT COLLECTION Standards for Waiver of Overpayments § 845.302 Fault. A recipient of an overpayment is without fault if he or she performed no act of commission or omission...

  3. 5 CFR 831.1402 - Fault.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 5 Administrative Personnel 2 2012-01-01 2012-01-01 false Fault. 831.1402 Section 831.1402...) RETIREMENT Standards for Waiver of Overpayments § 831.1402 Fault. A recipient of an overpayment is without fault if he/she performed no act of commission or omission which resulted in the overpayment. The...

  4. Ground Fault--A Health Hazard

    ERIC Educational Resources Information Center

    Jacobs, Clinton O.

    1977-01-01

    A ground fault is especially hazardous because the resistance through which the current is flowing to ground may be sufficient to cause electrocution. The Ground Fault Circuit Interrupter (G.F.C.I.) protects 15 and 25 ampere 120 volt circuits from ground fault condition. The design and examples of G.F.C.I. functions are described in this article.…

  5. Lake Tahoe Faults, Shaded Relief Map

    Shaded relief map of western part of the Lake Tahoe basin, California. Faults lines are dashed where approximately located, dotted where concealed, bar and ball on downthrown side. Heavier line weight shows principal range-front fault strands of the Tahoe-Sierra frontal fault zone (TSFFZ). Opaque wh...

  6. Reliability computation using fault tree analysis

    NASA Technical Reports Server (NTRS)

    Chelson, P. O.

    1971-01-01

    A method is presented for calculating event probabilities from an arbitrary fault tree. The method includes an analytical derivation of the system equation and is not a simulation program. The method can handle systems that incorporate standby redundancy and it uses conditional probabilities for computing fault trees where the same basic failure appears in more than one fault path.

  7. Fault-related clay authigenesis along the Moab Fault: Implications for calculations of fault rock composition and mechanical and hydrologic fault zone properties

    USGS Publications Warehouse

    Solum, J.G.; Davatzes, N.C.; Lockner, D.A.

    2010-01-01

    The presence of clays in fault rocks influences both the mechanical and hydrologic properties of clay-bearing faults, and therefore it is critical to understand the origin of clays in fault rocks and their distributions is of great importance for defining fundamental properties of faults in the shallow crust. Field mapping shows that layers of clay gouge and shale smear are common along the Moab Fault, from exposures with throws ranging from 10 to ???1000 m. Elemental analyses of four locations along the Moab Fault show that fault rocks are enriched in clays at R191 and Bartlett Wash, but that this clay enrichment occurred at different times and was associated with different fluids. Fault rocks at Corral and Courthouse Canyons show little difference in elemental composition from adjacent protolith, suggesting that formation of fault rocks at those locations is governed by mechanical processes. Friction tests show that these authigenic clays result in fault zone weakening, and potentially influence the style of failure along the fault (seismogenic vs. aseismic) and potentially influence the amount of fluid loss associated with coseismic dilation. Scanning electron microscopy shows that authigenesis promotes that continuity of slip surfaces, thereby enhancing seal capacity. The occurrence of the authigenesis, and its influence on the sealing properties of faults, highlights the importance of determining the processes that control this phenomenon. ?? 2010 Elsevier Ltd.

  8. Salton Sea Satellite Image Showing Fault Slip

    Landsat satellite image (LE70390372003084EDC00) showing location of surface slip triggered along faults in the greater Salton Trough area. Red bars show the generalized location of 2010 surface slip along faults in the central Salton Trough and many additional faults in the southwestern section of t...

  9. High temperature superconducting fault current limiter

    DOEpatents

    Hull, John R.

    1997-01-01

    A fault current limiter (10) for an electrical circuit (14). The fault current limiter (10) includes a high temperature superconductor (12) in the electrical circuit (14). The high temperature superconductor (12) is cooled below its critical temperature to maintain the superconducting electrical properties during operation as the fault current limiter (10).

  10. Fault Diagnosis in HVAC Chillers

    NASA Technical Reports Server (NTRS)

    Choi, Kihoon; Namuru, Setu M.; Azam, Mohammad S.; Luo, Jianhui; Pattipati, Krishna R.; Patterson-Hine, Ann

    2005-01-01

    Modern buildings are being equipped with increasingly sophisticated power and control systems with substantial capabilities for monitoring and controlling the amenities. Operational problems associated with heating, ventilation, and air-conditioning (HVAC) systems plague many commercial buildings, often the result of degraded equipment, failed sensors, improper installation, poor maintenance, and improperly implemented controls. Most existing HVAC fault-diagnostic schemes are based on analytical models and knowledge bases. These schemes are adequate for generic systems. However, real-world systems significantly differ from the generic ones and necessitate modifications of the models and/or customization of the standard knowledge bases, which can be labor intensive. Data-driven techniques for fault detection and isolation (FDI) have a close relationship with pattern recognition, wherein one seeks to categorize the input-output data into normal or faulty classes. Owing to the simplicity and adaptability, customization of a data-driven FDI approach does not require in-depth knowledge of the HVAC system. It enables the building system operators to improve energy efficiency and maintain the desired comfort level at a reduced cost. In this article, we consider a data-driven approach for FDI of chillers in HVAC systems. To diagnose the faults of interest in the chiller, we employ multiway dynamic principal component analysis (MPCA), multiway partial least squares (MPLS), and support vector machines (SVMs). The simulation of a chiller under various fault conditions is conducted using a standard chiller simulator from the American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE). We validated our FDI scheme using experimental data obtained from different types of chiller faults.

  11. Fault-Tolerant Heat Exchanger

    NASA Technical Reports Server (NTRS)

    Izenson, Michael G.; Crowley, Christopher J.

    2005-01-01

    A compact, lightweight heat exchanger has been designed to be fault-tolerant in the sense that a single-point leak would not cause mixing of heat-transfer fluids. This particular heat exchanger is intended to be part of the temperature-regulation system for habitable modules of the International Space Station and to function with water and ammonia as the heat-transfer fluids. The basic fault-tolerant design is adaptable to other heat-transfer fluids and heat exchangers for applications in which mixing of heat-transfer fluids would pose toxic, explosive, or other hazards: Examples could include fuel/air heat exchangers for thermal management on aircraft, process heat exchangers in the cryogenic industry, and heat exchangers used in chemical processing. The reason this heat exchanger can tolerate a single-point leak is that the heat-transfer fluids are everywhere separated by a vented volume and at least two seals. The combination of fault tolerance, compactness, and light weight is implemented in a unique heat-exchanger core configuration: Each fluid passage is entirely surrounded by a vented region bridged by solid structures through which heat is conducted between the fluids. Precise, proprietary fabrication techniques make it possible to manufacture the vented regions and heat-conducting structures with very small dimensions to obtain a very large coefficient of heat transfer between the two fluids. A large heat-transfer coefficient favors compact design by making it possible to use a relatively small core for a given heat-transfer rate. Calculations and experiments have shown that in most respects, the fault-tolerant heat exchanger can be expected to equal or exceed the performance of the non-fault-tolerant heat exchanger that it is intended to supplant (see table). The only significant disadvantages are a slight weight penalty and a small decrease in the mass-specific heat transfer.

  12. Focused exhumation along megathrust splay faults in Prince William Sound, Alaska

    NASA Astrophysics Data System (ADS)

    Haeussler, P. J.; Armstrong, P. A.; Liberty, L. M.; Ferguson, K.; Finn, S.; Arkle, J. C.; Pratt, T. L.

    2011-12-01

    Megathrust splay faults have been identified as important for generating tsunamis in some subduction zone earthquakes (1946 Nankai, 1964 Alaska, 2004 Sumatra). The larger role of megathrust splay faults in accretionary prisms is not well known. In Alaska, we have new evidence that megathrust splay faults are conduits for focused exhumation. In the southern Alaska accretionary complex, in the Prince William Sound region above the 1964 M9.2 earthquake rupture, apatite (U-Th)/He (AHe) ages, with closure temperatures of about 65°C, are typically in the range of 10-20 Ma. These relatively old ages indicate little to no accumulation of permanent strain during the megathrust earthquake cycle. However, the youngest AHe ages in all of Prince William Sound are from Montague Island, with two ages of 1.4 Ma on the southwest part of the island and two ages of 4 Ma at the northeast end of the island. Montague Island lies in the hanging wall of the Patton Bay megathrust splay fault, which ruptured during the 1964 earthquake, and resulted in 9 m of vertical uplift. Two other megathrust splay faults also ruptured during the 1964 earthquake in the same area. New high-resolution bathymetry and seismic reflection profiles show abundant normal faults in the region adjacent and north of the megathrust splay faults. The largest of these is the Montague Strait fault, which has 80 m of post glacial offset (~12kya?). We interpret this extension in the hanging wall as accommodating the exhumation of the rocks on Montague Island along the megathrust splay faults. An examination of legacy seismic reflection profiles shows the megathrust splay faults rooting downward into the decollement. At least some extension in the hanging wall may also be related to thrusting over a ramp-flat geometry. These megathrust splay faults are out of sequence thrusts, as they are located about 130 km inboard from the trench. This out of sequence thrusting that is causing the exhumation on Montague Island may be driven by underplating or by the Yakutat microplate collision. We suggest that rapid exhumation along megathrust splay faults, in association with normal faulting, may be a feature along other megathrust splay faults around the world.

  13. Active uplift and normal faulting in the eastern flank of Taiwan Central Range

    NASA Astrophysics Data System (ADS)

    Chang, Chung-Pai; Hsu, Yi-Chun; Kang, Chu-Chun

    2015-04-01

    As the backbone range of Taiwan orogen, the highest peaks of the Central Range have been uplifted to nearly 4 km above sea level. A rapid exhumation rate of about 6 mm/yr over the past several million years has been determined by many previous thermochronological studies in the eastern flank of the Central Range. However, the uplift mechanism of the Central Range is still in debate. Especially, the most important structural component, the Central Range Fault in the eastern boundary of the Central Range, has never been clearly observed in the previous studies. An east-vergent "backthrusting" or "backfolding" was firstly proposed by Ernst in 1977. However, normal faulting and oblique faulting with a normal component were also proposed by the following field workers (e.g., Crespi et al., 1996; Fisher, 1999). In this study, we use the geomorphic, stratigraphic, and structural analyses to figure out the near surface geometry of the Central Range Fault, and as well use the recent earthquake data to understand the deeper structures beneath the Central Range. By combining these results, we propose a doubly vergent model with a roll-back Central Range fault to explain the local structure and the rapid uplift of the eastern flank of the Central Range. The normal faults along the eastern flank of Central Range can also be separated into three segments form the north to the south. This late-stage structure suggests that the rotation-accommodating structure is extensional in nature.

  14. Mechanical Role of Fluids in Earthquakes and Faulting

    NASA Astrophysics Data System (ADS)

    Rice, J. R.

    2005-12-01

    Following the contributions of Hubbert and Rubey, the level of ambient pore pressure is of accepted importance for understanding the static frictional strength of faults. There are also important dynamical interactions between pore fluids and faulting. Some of those are addressed here, with examples to be chosen from the following: (1) Pore fluid presence at full saturation promotes strong localization in rapidly shearing granular materials, even in cases for which the friction coefficient increases rapidly with shearing rate [see Rice, Rudnicki and Tsai, this meeting]. (2) Thermal pressurization of earthquake faults during seismic slip may provide the primary weakening process during earthquakes in mature crustal fault zones; it provides a plausible basic explanation, based on geological and laboratory data, of the magnitudes of the fracture energies of earthquakes as inferred independently from seismological data [see web link below]. The process also seems to be active in some large landslides. (3) Pore pressure alterations are induced by rapid mode II slip on fault planes when they have bordering gouge or damage zones which are of dissimilar permeability and/or poroelastic properties. This provides a fuller, new perspective on effects of material dissimilarity across a slip surface on altering the effective normal stress and thus interacting with dynamic rupture [see Rudnicki and Rice, this meeting]. (4) Gouge dilatancy associated with slip-rate increases induces suction in the pore fluid, so as to partially stabilize faults against earthquake nucleation, and also to slow rupture propagation into shallow fault regions. An open question is that of when and if shear heating acts to aid nucleation; the effect seems negligible for nucleation under slow tectonic loading but may be important for nucleation driven by sudden steps in stress. (5) Permeability determines pore pressure gradients for given flow rates, but increases in pore pressure cause increases in permeability. That allows slow solitary waves of pore pressure increase which propagate upwards against gravity in fault zones that are reasonably sealed from their surroundings, following initiation by, e.g., breaching of a pressurized seal at depth. (6) Aseismic slip transients in subduction zones occur in an environment of active compaction and metamorphic fluid release, and fluids seem responsible for associated tremor as well. Recent modeling [see Liu and Rice, this meeting] links elevation of fluid pressure to the speed of along-strike propagation of slip transients. (7) Poroelastic responses to stress transfer have been detected for some earthquakes, and associated transient stress changes may play a role in aftershock sequences, although probably secondary in general. (8) Another type of fluid saturated ``fault zone'', in granulated sediments between dissimilar materials, is the bed of a mobile ice sheet. Some of the concepts in topics 1 to 4 above may have application to surges, ice streams, and glacial earthquakes. These various cases 1 to 8 involve many contributors in the geophysical community, and include collaborative current or recent studies of the author with Massimo Cocco (2), Yajing Liu (4, 6), Alan Rempel (2), John Rudnicki (1,3), Paul Segall (4), and Victor Tsai (1,8).

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  16. Seismic slip on an upper-plate normal fault during a large subduction megathrust rupture

    NASA Astrophysics Data System (ADS)

    Hicks, Stephen P.; Rietbrock, Andreas

    2015-12-01

    Quantification of stress accumulation and release during subduction zone seismic cycles requires an understanding of the distribution of fault slip during earthquakes. Reconstructions of slip are typically constrained to a single, known fault plane. Yet, slip has been shown to occur on multiple faults within the subducting plate owing to stress triggering, resulting in phenomena such as earthquake doublets. However, rapid stress triggering from the plate interface to faults in the overriding plate has not been documented. Here we analyse seismic data from the magnitude 7.1 Araucania earthquake that occurred in the Chilean subduction zone in 2011. We find that the earthquake, which was reported as a single event in global moment tensor solutions, was instead composed of two ruptures on two separate faults. Within 12 s a thrust earthquake on the plate interface triggered a second large rupture on a normal fault 30 km away in the overriding plate. This configuration of partitioned rupture is consistent with normal-faulting mechanisms in the ensuing aftershock sequence. We conclude that plate interface rupture can trigger almost instantaneous slip in the overriding plate of a subduction zone. This shallow upper-plate rupture may be masked from teleseismic data, posing a challenge for real-time tsunami warning systems.

  17. Numerical model of formation of a 3-D strike-slip fault system

    NASA Astrophysics Data System (ADS)

    Chemenda, Alexandre I.; Cavalié, Olivier; Vergnolle, Mathilde; Bouissou, Stéphane; Delouis, Bertrand

    2016-01-01

    The initiation and the initial evolution of a strike-slip fault are modeled within an elastoplasticity constitutive framework taking into account the evolution of the hardening modulus with inelastic straining. The initial and boundary conditions are similar to those of the Riedel shear experiment. The models first deform purely elastically. Then damage (inelastic deformation) starts at the model surface. The damage zone propagates both normal to the forming fault zone and downwards. Finally, it affects the whole layer thickness, forming flower-like structure in cross-section. At a certain stage, a dense set of parallel Riedel shears forms at shallow depth. A few of these propagate both laterally and vertically, while others die. The faults first propagate in-plane, but then rapidly change direction to make a larger angle with the shear axis. New fault segments form as well, resulting in complex 3-D fault zone architecture. Different fault segments accommodate strike-slip and normal displacements, which results in the formation of valleys and rotations along the fault system.

  18. Dislocation model for aseismic fault slip in the transverse ranges of Southern California

    NASA Technical Reports Server (NTRS)

    Cheng, A.; Jackson, D. D.; Matsuura, M.

    1985-01-01

    Geodetic data at a plate boundary can reveal the pattern of subsurface displacements that accompany plate motion. These displacements are modelled as the sum of rigid block motion and the elastic effects of frictional interaction between blocks. The frictional interactions are represented by uniform dislocation on each of several rectangular fault patches. The block velocities and fault parameters are then estimated from geodetic data. Bayesian inversion procedure employs prior estimates based on geological and seismological data. The method is applied to the Transverse Ranges, using prior geological and seismological data and geodetic data from the USGS trilateration networks. Geodetic data imply a displacement rate of about 20 mm/yr across the San Andreas Fault, while the geologic estimates exceed 30 mm/yr. The prior model and the final estimates both imply about 10 mm/yr crustal shortening normal to the trend of the San Andreas Fault. Aseismic fault motion is a major contributor to plate motion. The geodetic data can help to identify faults that are suffering rapid stress accumulation; in the Transverse Ranges those faults are the San Andreas and the Santa Susana.

  19. Drill Bit Noise Illuminates the San Andreas Fault

    NASA Astrophysics Data System (ADS)

    Vasconcelos, Ivan; Snieder, Roel; Sava, Paul; Taylor, Tom; Malin, Peter; Chavarria, Andres

    2008-09-01

    Extracting the vibration response of the subsurface from noise is a rapidly growing field of research [Curtis et al., 2006; Larose et al., 2006]. We carried out broadside imaging of the San Andreas fault zone (SAFZ) using drill bit noise created in the main hole of the San Andreas Fault Observatory at Depth (SAFOD), near Parkfield, Calif. Imaging with drill bit noise is not new, but it traditionally requires the measurement of the vibrations of the drill stem [Rector and Marion, 1991]; such measurements provide the waves radiated by the drill bit. At SAFOD, these measurements were not available due to the absence of an accelerometer mounted on the drill stem. For this reason, the new technique of deconvolution interferometry was used [Vasconcelos and Snieder, 2008]. This technique extracts the waves propagating between seismometers from recordings of incoherent noise.

  20. Predeployment validation of fault-tolerant systems through software-implemented fault insertion

    NASA Technical Reports Server (NTRS)

    Czeck, Edward W.; Siewiorek, Daniel P.; Segall, Zary Z.

    1989-01-01

    Fault injection-based automated testing (FIAT) environment, which can be used to experimentally characterize and evaluate distributed realtime systems under fault-free and faulted conditions is described. A survey is presented of validation methodologies. The need for fault insertion based on validation methodologies is demonstrated. The origins and models of faults, and motivation for the FIAT concept are reviewed. FIAT employs a validation methodology which builds confidence in the system through first providing a baseline of fault-free performance data and then characterizing the behavior of the system with faults present. Fault insertion is accomplished through software and allows faults or the manifestation of faults to be inserted by either seeding faults into memory or triggering error detection mechanisms. FIAT is capable of emulating a variety of fault-tolerant strategies and architectures, can monitor system activity, and can automatically orchestrate experiments involving insertion of faults. There is a common system interface which allows ease of use to decrease experiment development and run time. Fault models chosen for experiments on FIAT have generated system responses which parallel those observed in real systems under faulty conditions. These capabilities are shown by two example experiments each using a different fault-tolerance strategy.

  1. Novel neural networks-based fault tolerant control scheme with fault alarm.

    PubMed

    Shen, Qikun; Jiang, Bin; Shi, Peng; Lim, Cheng-Chew

    2014-11-01

    In this paper, the problem of adaptive active fault-tolerant control for a class of nonlinear systems with unknown actuator fault is investigated. The actuator fault is assumed to have no traditional affine appearance of the system state variables and control input. The useful property of the basis function of the radial basis function neural network (NN), which will be used in the design of the fault tolerant controller, is explored. Based on the analysis of the design of normal and passive fault tolerant controllers, by using the implicit function theorem, a novel NN-based active fault-tolerant control scheme with fault alarm is proposed. Comparing with results in the literature, the fault-tolerant control scheme can minimize the time delay between fault occurrence and accommodation that is called the time delay due to fault diagnosis, and reduce the adverse effect on system performance. In addition, the FTC scheme has the advantages of a passive fault-tolerant control scheme as well as the traditional active fault-tolerant control scheme's properties. Furthermore, the fault-tolerant control scheme requires no additional fault detection and isolation model which is necessary in the traditional active fault-tolerant control scheme. Finally, simulation results are presented to demonstrate the efficiency of the developed techniques. PMID:25014982

  2. Multiple Fault Isolation in Redundant Systems

    NASA Technical Reports Server (NTRS)

    Pattipati, Krishna R.

    1997-01-01

    Fault diagnosis in large-scale systems that are products of modem technology present formidable challenges to manufacturers and users. This is due to large number of failure sources in such systems and the need to quickly isolate and rectify failures with minimal down time. In addition, for fault-tolerant systems and systems with infrequent opportunity for maintenance (e.g., Hubble telescope, space station), the assumption of at most a single fault in the system is unrealistic. In this project, we have developed novel block and sequential diagnostic strategies to isolate multiple faults in the shortest possible time without making the unrealistic single fault assumption.

  3. Managing Space System Faults: Coalescing NASA's Views

    NASA Technical Reports Server (NTRS)

    Muirhead, Brian; Fesq, Lorraine

    2012-01-01

    Managing faults and their resultant failures is a fundamental and critical part of developing and operating aerospace systems. Yet, recent studies have shown that the engineering "discipline" required to manage faults is not widely recognized nor evenly practiced within the NASA community. Attempts to simply name this discipline in recent years has been fraught with controversy among members of the Integrated Systems Health Management (ISHM), Fault Management (FM), Fault Protection (FP), Hazard Analysis (HA), and Aborts communities. Approaches to managing space system faults typically are unique to each organization, with little commonality in the architectures, processes and practices across the industry.

  4. Multiple Fault Isolation in Redundant Systems

    NASA Technical Reports Server (NTRS)

    Pattipati, Krishna R.; Patterson-Hine, Ann; Iverson, David

    1997-01-01

    Fault diagnosis in large-scale systems that are products of modern technology present formidable challenges to manufacturers and users. This is due to large number of failure sources in such systems and the need to quickly isolate and rectify failures with minimal down time. In addition, for fault-tolerant systems and systems with infrequent opportunity for maintenance (e.g., Hubble telescope, space station), the assumption of at most a single fault in the system is unrealistic. In this project, we have developed novel block and sequential diagnostic strategies to isolate multiple faults in the shortest possible time without making the unrealistic single fault assumption.

  5. A New Method for Node Fault Detection in Wireless Sensor Networks

    PubMed Central

    Jiang, Peng

    2009-01-01

    Wireless sensor networks (WSNs) are an important tool for monitoring distributed remote environments. As one of the key technologies involved in WSNs, node fault detection is indispensable in most WSN applications. It is well known that the distributed fault detection (DFD) scheme checks out the failed nodes by exchanging data and mutually testing among neighbor nodes in this network., but the fault detection accuracy of a DFD scheme would decrease rapidly when the number of neighbor nodes to be diagnosed is small and the node's failure ratio is high. In this paper, an improved DFD scheme is proposed by defining new detection criteria. Simulation results demonstrate that the improved DFD scheme performs well in the above situation and can increase the fault detection accuracy greatly. PMID:22399967

  6. Stressing of fault patch during seismic swarms in central Apennines, Italy

    NASA Astrophysics Data System (ADS)

    De Gori, P.; Lucente, F. P.; Chiarabba, C.

    2015-04-01

    Persistent seismic swarms originate along the normal faulting system of central Apennines (Italy). In this study, we analyze the space-time-energy distribution of one of the longer and more intense of these swarms, active since August 2013 in the high seismic risk area of the Gubbio basin. Our aim is to verify if information relevant to constraint short-term earthquake occurrence scenarios is hidden in seismic swarms. During the swarm, the seismic moment release first accelerated, with a rapid migration of seismicity along the fault system, and suddenly dropped. We observe a decrease of the b-value, along the portion of the fault system where large magnitude events concentrated, possibly indicating that a fault patch was dynamically stressed. This finding suggests that the onset of seismic swarms might help the formation of critically stressed patches.

  7. Silica Lubrication in Faults (Invited)

    NASA Astrophysics Data System (ADS)

    Rowe, C. D.; Rempe, M.; Lamothe, K.; Kirkpatrick, J. D.; White, J. C.; Mitchell, T. M.; Andrews, M.; Di Toro, G.

    2013-12-01

    Silica-rich rocks are common in the crust, so silica lubrication may be important for causing fault weakening during earthquakes if the phenomenon occurs in nature. In laboratory friction experiments on chert, dramatic shear weakening has been attributed to amorphization and attraction of water from atmospheric humidity to form a 'silica gel'. Few observations of the slip surfaces have been reported, and the details of weakening mechanism(s) remain enigmatic. Therefore, no criteria exist on which to make comparisons of experimental materials to natural faults. We performed a series of friction experiments, characterized the materials formed on the sliding surface, and compared these to a geological fault in the same rock type. Experiments were performed in the presence of room humidity at 2.5 MPa normal stress with 3 and 30 m total displacement for a variety of slip rates (10-4 - 10-1 m/s). The friction coefficient (μ) reduced from >0.6 to ~0.2 at 10-1 m/s, but only fell to ~0.4 at 10-2 - 10-4 m/s. The slip surfaces and wear material were observed using laser confocal Raman microscopy, electron microprobe, X-ray diffraction, and transmission electron microscopy. Experiments at 10-1 m/s formed wear material consisting of ≤1 μm powder that is aggregated into irregular 5-20 μm clumps. Some material disaggregated during analysis with electron beams and lasers, suggesting hydrous and unstable components. Compressed powder forms smooth pavements on the surface in which grains are not visible (if present, they are <100 nm). Powder contains amorphous material and as yet unidentified crystalline and non-crystalline forms of silica (not quartz), while the worn chert surface underneath shows Raman spectra consistent with a mixture of quartz and amorphous material. If silica amorphization facilitates shear weakening in natural faults, similar wear materials should be formed, and we may be able to identify them through microstructural studies. However, the sub-micron particles of unstable materials are unlikely to survive in the crust over geologic time, so a direct comparison of fresh experimental wear material and ancient fault rock needs to account for the alteration and crystallization of primary materials. The surface of the Corona fault is coated by a translucent shiny layer consisting of ~100 nm interlocking groundmass of dislocation-free quartz, 10 nm ellipsoidal particles, and interstitial patches of amorphous silica. We interpret this layer as the equivalent of the experimentally produced amorphous material after crystallizing to more stable forms over geological time.

  8. Fault diagnosis for magnetic bearing systems

    NASA Astrophysics Data System (ADS)

    Tsai, Nan-Chyuan; King, Yueh-Hsun; Lee, Rong-Mao

    2009-05-01

    A full fault diagnosis for active magnetic bearing (AMB) and rotor systems to monitor the closed-loop operation and analyze fault patterns on-line in case any malfunction occurs is proposed in this paper. Most traditional approaches for fault diagnosis are based on actuator or sensor diagnosis individually and can solely detect a single fault at a time. This research combines two diagnosis methodologies by using both state estimators and parameter estimators to detect, identify and analyze actuators and sensors faults in AMB/rotor systems. The proposed fault diagnosis algorithm not only enhances the diagnosis accuracy, but also illustrates the capability to detect multiple sensors faults which occur concurrently. The efficacy of the presented algorithm has been verified by computer simulations and intensive experiments. The test rig for experiments is equipped with AMB, interface module (dSPACE DS1104), data acquisition unit MATLAB/Simulink simulation environment. At last, the fault patterns, such as bias, multiplicative loop gain variation and noise addition, can be identified by the algorithm presented in this work. In other words, the proposed diagnosis algorithm is able to detect faults at the first moment, find which sensors or actuators under failure and identify which fault pattern the found faults belong to.

  9. A Quaternary fault database for central Asia

    NASA Astrophysics Data System (ADS)

    Mohadjer, Solmaz; Ehlers, Todd Alan; Bendick, Rebecca; Stübner, Konstanze; Strube, Timo

    2016-02-01

    Earthquakes represent the highest risk in terms of potential loss of lives and economic damage for central Asian countries. Knowledge of fault location and behavior is essential in calculating and mapping seismic hazard. Previous efforts in compiling fault information for central Asia have generated a large amount of data that are published in limited-access journals with no digital maps publicly available, or are limited in their description of important fault parameters such as slip rates. This study builds on previous work by improving access to fault information through a web-based interactive map and an online database with search capabilities that allow users to organize data by different fields. The data presented in this compilation include fault location, its geographic, seismic, and structural characteristics, short descriptions, narrative comments, and references to peer-reviewed publications. The interactive map displays 1196 fault traces and 34 000 earthquake locations on a shaded-relief map. The online database contains attributes for 123 faults mentioned in the literature, with Quaternary and geodetic slip rates reported for 38 and 26 faults respectively, and earthquake history reported for 39 faults. All data are accessible for viewing and download via http://www.geo.uni-tuebingen.de/faults/. This work has implications for seismic hazard studies in central Asia as it summarizes important fault parameters, and can reduce earthquake risk by enhancing public access to information. It also allows scientists and hazard assessment teams to identify structures and regions where data gaps exist and future investigations are needed.

  10. Model-Based Fault Tolerant Control

    NASA Technical Reports Server (NTRS)

    Kumar, Aditya; Viassolo, Daniel

    2008-01-01

    The Model Based Fault Tolerant Control (MBFTC) task was conducted under the NASA Aviation Safety and Security Program. The goal of MBFTC is to develop and demonstrate real-time strategies to diagnose and accommodate anomalous aircraft engine events such as sensor faults, actuator faults, or turbine gas-path component damage that can lead to in-flight shutdowns, aborted take offs, asymmetric thrust/loss of thrust control, or engine surge/stall events. A suite of model-based fault detection algorithms were developed and evaluated. Based on the performance and maturity of the developed algorithms two approaches were selected for further analysis: (i) multiple-hypothesis testing, and (ii) neural networks; both used residuals from an Extended Kalman Filter to detect the occurrence of the selected faults. A simple fusion algorithm was implemented to combine the results from each algorithm to obtain an overall estimate of the identified fault type and magnitude. The identification of the fault type and magnitude enabled the use of an online fault accommodation strategy to correct for the adverse impact of these faults on engine operability thereby enabling continued engine operation in the presence of these faults. The performance of the fault detection and accommodation algorithm was extensively tested in a simulation environment.

  11. Wrench faulting using seismic and Landsat

    SciTech Connect

    Bolden, G.P.

    1987-05-01

    Two high-multiplicity seismic profiles demonstrate the compressional nature of the faulting along the Double Mountain Lineament in northeast Garza County in the Permian basin. NASA high-altitude aircraft imagery using Landsat parameters delineate the traces of these faults on the surface. The drainage system also defines the fault traces by following the zones of fracture and weakness in the Permian and Triassic outcrops. A north-south seismic profile crosses the Double Mountain lineament (P Shear), defining two thrust faults, two high-angle reverse faults and a pop-up block (flow structure). NASA high-altitude imagery and stream drainage indicate the traces of these faults. The pattern developed fits the definition of left lateral wrench faulting. Overlying carbonate shelf margins are developed above the underlying structure, which further enhances the structural interpretation. An east-west seismic profile 3 mi southeast of the north-south profile again defines the Double Mountain Lineament or P Shear and the associated faulting. A 1-mi wide pop-up block with a high angle reverse fault on both sides demonstrates the compressional nature of the faulting, and the high-altitude imagery delineates the surface traces of the faults. This structure has been drilled with several Stawn and Ellenburger producers, confirming the seismic and surface interpretations in the subsurface.

  12. Tool for Viewing Faults Under Terrain

    NASA Technical Reports Server (NTRS)

    Siegel, Herbert, L.; Li, P. Peggy

    2005-01-01

    Multi Surface Light Table (MSLT) is an interactive software tool that was developed in support of the QuakeSim project, which has created an earthquake- fault database and a set of earthquake- simulation software tools. MSLT visualizes the three-dimensional geometries of faults embedded below the terrain and animates time-varying simulations of stress and slip. The fault segments, represented as rectangular surfaces at dip angles, are organized into collections, that is, faults. An interface built into MSLT queries and retrieves fault definitions from the QuakeSim fault database. MSLT also reads time-varying output from one of the QuakeSim simulation tools, called "Virtual California." Stress intensity is represented by variations in color. Slips are represented by directional indicators on the fault segments. The magnitudes of the slips are represented by the duration of the directional indicators in time. The interactive controls in MSLT provide a virtual track-ball, pan and zoom, translucency adjustment, simulation playback, and simulation movie capture. In addition, geographical information on the fault segments and faults is displayed on text windows. Because of the extensive viewing controls, faults can be seen in relation to one another, and to the terrain. These relations can be realized in simulations. Correlated slips in parallel faults are visible in the playback of Virtual California simulations.

  13. Frictional strength and heat flow of southern San Andreas Fault

    NASA Astrophysics Data System (ADS)

    Zhu, P. P.

    2016-01-01

    Frictional strength and heat flow of faults are two related subjects in geophysics and seismology. To date, the investigation on regional frictional strength and heat flow still stays at the stage of qualitative estimation. This paper is concentrated on the regional frictional strength and heat flow of the southern San Andreas Fault (SAF). Based on the in situ borehole measured stress data, using the method of 3D dynamic faulting analysis, we quantitatively determine the regional normal stress, shear stress, and friction coefficient at various seismogenic depths. These new data indicate that the southern SAF is a weak fault within the depth of 15 km. As depth increases, all the regional normal and shear stresses and friction coefficient increase. The former two increase faster than the latter. Regional shear stress increment per kilometer equals 5.75 ± 0.05 MPa/km for depth ≤15 km; regional normal stress increment per kilometer is equal to 25.3 ± 0.1 MPa/km for depth ≤15 km. As depth increases, regional friction coefficient increment per kilometer decreases rapidly from 0.08 to 0.01/km at depths less than ~3 km. As depth increases from ~3 to ~5 km, it is 0.01/km and then from ~5 to 15 km, and it is 0.002/km. Previously, frictional strength could be qualitatively determined by heat flow measurements. It is difficult to obtain the quantitative heat flow data for the SAF because the measured heat flow data exhibit large scatter. However, our quantitative results of frictional strength can be employed to investigate the heat flow in the southern SAF. We use a physical quantity P f to describe heat flow. It represents the dissipative friction heat power per unit area generated by the relative motion of two tectonic plates accommodated by off-fault deformation. P f is called "fault friction heat." On the basis of our determined frictional strength data, utilizing the method of 3D dynamic faulting analysis, we quantitatively determine the regional long-term fault friction heat at various seismogenic depths in the southern SAF. The new data show that as depth increases, regional friction stress increases within the depth of 15 km; its increment per kilometer equals 5.75 ± 0.05 MPa/km. As depth increases, regional long-term fault friction heat increases; its increment per kilometer is equal to 3.68 ± 0.03 mW/m2/km. The values of regional long-term fault friction heat provided by this study are always lower than those from heat flow measurements. The difference between them and the scatter existing in the measured heat flow data are mainly caused by the following processes: (i) heat convection, (ii) heat advection, (iii) stress accumulation, (iv) seismic bursts between short-term lull periods in a long-term period, and (v) influence of seismicity in short-term periods upon long-term slip rate and heat flow. Fault friction heat is a fundamental parameter in research on heat flow.

  14. Multiple Fault Isolation in Redundant Systems

    NASA Technical Reports Server (NTRS)

    Shakeri, M.; Pattipati, Krishna R.; Raghavan, V.; Patterson-Hine, Ann; Iverson, David L.

    1997-01-01

    We consider the problem of sequencing tests to isolate multiple faults in redundant (fault-tolerant) systems with minimum expected testing cost (time). It can be shown that single faults and minimal faults, i.e., minimum number of failures with a failure signature different from the union of failure signatures of individual failures, together with their failure signatures, constitute the necessary information for fault diagnosis in redundant systems. In this paper, we develop an algorithm to find all the minimal faults and their failure signatures. Then, we extend the Sure diagnostic strategies [1] of our previous work to diagnose multiple faults in redundant systems. The proposed algorithms and strategies are illustrated using several examples.

  15. Arc burst pattern analysis fault detection system

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

    A method and apparatus are provided for detecting an arcing fault on a power line carrying a load current. Parameters indicative of power flow and possible fault events on the line, such as voltage and load current, are monitored and analyzed for an arc burst pattern exhibited by arcing faults in a power system. These arcing faults are detected by identifying bursts of each half-cycle of the fundamental current. Bursts occurring at or near a voltage peak indicate arcing on that phase. Once a faulted phase line is identified, a comparison of the current and voltage reveals whether the fault is located in a downstream direction of power flow toward customers, or upstream toward a generation station. If the fault is located downstream, the line is de-energized, and if located upstream, the line may remain energized to prevent unnecessary power outages.

  16. Fibre bundle framework for quantum fault tolerance

    NASA Astrophysics Data System (ADS)

    Zhang, Lucy Liuxuan; Gottesman, Daniel

    2014-03-01

    We introduce a differential geometric framework for describing families of quantum error-correcting codes and for understanding quantum fault tolerance. In particular, we use fibre bundles and a natural projectively flat connection thereon to study the transformation of codewords under unitary fault-tolerant evolutions. We'll explain how the fault-tolerant logical operations are given by the monodromy group for the bundles with projectively flat connection, which is always discrete. We will discuss the construction of the said bundles for two examples of fault-tolerant families of operations, the string operators in the toric code and the qudit transversal gates. This framework unifies topological fault tolerance and fault tolerance based on transversal gates, and is expected to apply for all unitary quantum fault-tolerant protocols.

  17. Fault tolerant high-performance PACS network design and implementation

    NASA Astrophysics Data System (ADS)

    Chimiak, William J.; Boehme, Johannes M.

    1998-07-01

    The Wake Forest University School of Medicine and the Wake Forest University/Baptist Medical Center (WFUBMC) are implementing a second generation PACS. The first generation PACS provided helpful information about the functional and temporal requirements of the system. It highlighted the importance of image retrieval speed, system availability, RIS/HIS integration, the ability to rapidly view images on any PACS workstation, network bandwidth, equipment redundancy, and the ability for the system to evolve using standards-based components. This paper deals with the network design and implementation of the PACS. The physical layout of the hospital areas served by the PACS, the choice of network equipment and installation issues encountered are addressed. Efforts to optimize fault tolerance are discussed. The PACS network is a gigabit, mixed-media network based on LAN emulation over ATM (LANE) with a rapid migration from LANE to Multiple Protocols Over ATM (MPOA) planned. Two fault-tolerant backbone ATM switches serve to distribute network accesses with two load-balancing 622 megabit per second (Mbps) OC-12 interconnections. The switch was sized to be upgradable to provide a 2.54 Gbps OC-48 interconnection with an OC-12 interconnection as a load-balancing backup. Modalities connect with legacy network interface cards to a switched-ethernet device. This device has two 155 Mbps OC-3 load-balancing uplinks to each of the backbone ATM switches of the PACS. This provides a fault-tolerant logical connection to the modality servers which pass verified DICOM images to the PACS servers and proper PACS diagnostic workstations. Where fiber pulls were prohibitively expensive, edge ATM switches were installed with an OC-12 uplink to a backbone ATM switches. The PACS and data base servers are fault-tolerant, hot-swappable Sun Enterprise Servers with an OC-12 connection to a backbone ATM switch and a fast-ethernet connection to a back-up network. The workstations come with 10/100 BASET autosense cards. A redundant switched-ethernet network will be installed to provide yet another degree of network fault-tolerance. The switched-ethernet devices are connected to each of the backbone ATM switches with two-load-balancing OC-3 connections to provide fault-tolerant connectivity in the event of a primary network failure.

  18. Rapid weight loss

    MedlinePlus

    ... loss-rapid weight loss; Overweight-rapid weight loss; Obesity-rapid weight loss; Diet-rapid weight loss ... for people who have health problems because of obesity. For these people, losing a lot of weight ...

  19. A “mesh” of crossing faults: Fault networks of southern California

    NASA Astrophysics Data System (ADS)

    Janecke, S. U.

    2009-12-01

    Detailed geologic mapping of active fault systems in the western Salton Trough and northern Peninsular Ranges of southern California make it possible to expand the inventory of mapped and known faults by compiling and updating existing geologic maps, and analyzing high resolution imagery, LIDAR, InSAR, relocated hypocenters and other geophysical datasets. A fault map is being compiled on Google Earth and will ultimately discriminate between a range of different fault expressions: from well-mapped faults to subtle lineaments and geomorphic anomalies. The fault map shows deformation patterns in both crystalline and basinal deposits and reveals a complex fault mesh with many curious and unexpected relationships. Key findings are: 1) Many fault systems have mutually interpenetrating geometries, are grossly coeval, and allow faults to cross one another. A typical relationship reveals a dextral fault zone that appears to be continuous at the regional scale. In detail, however, there are no continuous NW-striking dextral fault traces and instead the master dextral fault is offset in a left-lateral sense by numerous crossing faults. Left-lateral faults also show small offsets where they interact with right lateral faults. Both fault sets show evidence of Quaternary activity. Examples occur along the Clark, Coyote Creek, Earthquake Valley and Torres Martinez fault zones. 2) Fault zones cross in other ways. There are locations where active faults continue across or beneath significant structural barriers. Major fault zones like the Clark fault of the San Jacinto fault system appears to end at NE-striking sinistral fault zones (like the Extra and Pumpkin faults) that clearly cross from the SW to the NE side of the projection of the dextral traces. Despite these blocking structures, there is good evidence for continuation of the dextral faults on the opposite sides of the crossing fault array. In some instances there is clear evidence (in deep microseismic alignments of hypocenters) that the master dextral faults zones pass beneath shallower crossing fault arrays above them and this mechanism may transfer strain through the blocking zones. 3) The curvature of strands of the Coyote Creek fault and the Elsinore fault are similar along their SE 60 km. The scale, locations and concavity of bends are so similar that their shape appears to be coordinated. The matching contractional and extensional bends suggests that originally straighter dextral fault zones may be deforming in response of coeval sinistral deformation between, beneath, and around them. 4) Deformation is strongly domainal with one style or geometry of structure dominating in one area then another in an adjacent area. Boundaries may be abrupt. 5) There are drastic lateral changes in the width of damage zones adjacent to master faults. Outlines of the deformation related to some dextral fault zones resemble a snake that has ingested a squirming cat or soccer ball. 6) A mesh of interconnected faults seems to transfer slip back and forth between structures. 7) Scarps are not necessarily more abundant on the long master faults than on connector or crossing faults. Much remains to be learned upon completion the fault map.

  20. Tracing the Geomorphic Signature of Lateral Faulting

    NASA Astrophysics Data System (ADS)

    Duvall, A. R.; Tucker, G. E.

    2012-12-01

    Active strike-slip faults are among the most dangerous geologic features on Earth. Unfortunately, it is challenging to estimate their slip rates, seismic hazard, and evolution over a range of timescales. An under-exploited tool in strike-slip fault characterization is quantitative analysis of the geomorphic response to lateral fault motion to extract tectonic information directly from the landscape. Past geomorphic work of this kind has focused almost exclusively on vertical motion, despite the ubiquity of horizontal motion in crustal deformation and mountain building. We seek to address this problem by investigating the landscape response to strike-slip faulting in two ways: 1) examining the geomorphology of the Marlborough Fault System (MFS), a suite of parallel strike-slip faults within the actively deforming South Island of New Zealand, and 2) conducting controlled experiments in strike-slip landscape evolution using the CHILD landscape evolution model. The MFS offers an excellent natural experiment site because fault initiation ages and cumulative displacements decrease from north to south, whereas slip rates increase over four fold across a region underlain by a single bedrock unit (Torlesse Greywacke). Comparison of planform and longitudinal profiles of rivers draining the MFS reveals strong disequilibrium within tributaries that drain to active fault strands, and suggests that river capture related to fault activity may be a regular process in strike-slip fault zones. Simple model experiments support this view. Model calculations that include horizontal motion as well as vertical uplift demonstrate river lengthening and shortening due to stream capture in response to shutter ridges sliding in front of stream outlets. These results suggest that systematic variability in fluvial knickpoint location, drainage area, and incision rates along different faults or fault segments may be expected in catchments upstream of strike-slip faults and could act as useful indicators of fault activity.

  1. Electromagnetic imaging of active fault zones

    NASA Astrophysics Data System (ADS)

    Bedrosian, Paul Andrew

    Electromagnetic methods such as magnetotellurics (MT) are well suited for imaging the nature of continental faulting on both local and regional scales. These methods are sensitive to both the contrast in resistivity often found across a fault as well as zones of fluids and/or physically altered materials located within an active fault. High resolution MT studies of the San Andreas fault (SAF) near Hollister, California have imaged a zone of high fluid content flanking the SAF and extending to mid-crustal depths. The spatial relation between this zone and local seismicity suggests that the presence of fluids inhibits seismicity within the upper crust (0--4km). In the region examined, the San Andreas fault acts as a conduit for along-strike fluid flow yet acts as a barrier for fluid flow across the fault. Combined with previous work, these results suggest that the geologic setting of the SAF gives rise to the observed distribution of fluids in and surrounding the fault, as well as the observed along-strike variation in seismicity. Regional magnetotelluric studies of faulting in the northeast corner of the Tibetan plateau have helped establish the style and extent of faulting in the region. A series of MT profiles crossing the Altyn Tagh fault near its eastern terminus have been analyzed. One of these profiles additionally crosses a sequence of thrust faults which absorb the strain associated with this fault termination. Together with geologic timing information, the extent of underthrust sediments has been used to establish the rates of convergence and uplift of this proto-plateau. Additionally, the Altyn Tagh fault is imaged to be vertical from the surface to mid-crustal depths, and flanked by an extensive conductive zone which suggests that the present-day fault may have activated along a pre-existing suture.

  2. Stacking faults in Si nanocrystals

    SciTech Connect

    Wang, Y.Q.; Smirani, R.; Ross, G.G.

    2005-05-30

    Si nanocrystals (Si nc) were formed by the implantation of Si{sup +} into a SiO{sub 2} film on (100) Si, followed by high-temperature annealing. High-resolution transmission electron microscopy has been used to examine the microstructure of the Si nc produced by a high-dose (3x10{sup 17} cm{sup -2}) implantation. It is shown that there are only stacking-fault (SF) defects in some nanocrystals; while in others the stacking faults (SFs) coexist with twins. Two kinds of SFs, one being an intrinsic SF, the other being an extrinsic SF, have been observed inside the Si nc. More intrinsic SFs have been found in the Si nc, and the possible reasons are discussed. These microstructural defects are expected to play an important role in the light emission from the Si nc.

  3. Fault Injection Techniques and Tools

    NASA Technical Reports Server (NTRS)

    Hsueh, Mei-Chen; Tsai, Timothy K.; Iyer, Ravishankar K.

    1997-01-01

    Dependability evaluation involves the study of failures and errors. The destructive nature of a crash and long error latency make it difficult to identify the causes of failures in the operational environment. It is particularly hard to recreate a failure scenario for a large, complex system. To identify and understand potential failures, we use an experiment-based approach for studying the dependability of a system. Such an approach is applied not only during the conception and design phases, but also during the prototype and operational phases. To take an experiment-based approach, we must first understand a system's architecture, structure, and behavior. Specifically, we need to know its tolerance for faults and failures, including its built-in detection and recovery mechanisms, and we need specific instruments and tools to inject faults, create failures or errors, and monitor their effects.

  4. Perspective View, San Andreas Fault

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The prominent linear feature straight down the center of this perspective view is California's famous San Andreas Fault. The image, created with data from NASA's Shuttle Radar Topography Mission (SRTM), will be used by geologists studying fault dynamics and landforms resulting from active tectonics. This segment of the fault lies west of the city of Palmdale, Calif., about 100 kilometers (about 60 miles) northwest of Los Angeles. The fault is the active tectonic boundary between the North American plate on the right, and the Pacific plate on the left. Relative to each other, the Pacific plate is moving away from the viewer and the North American plate is moving toward the viewer along what geologists call a right lateral strike-slip fault. Two large mountain ranges are visible, the San Gabriel Mountains on the left and the Tehachapi Mountains in the upper right. Another fault, the Garlock Fault lies at the base of the Tehachapis; the San Andreas and the Garlock Faults meet in the center distance near the town of Gorman. In the distance, over the Tehachapi Mountains is California's Central Valley. Along the foothills in the right hand part of the image is the Antelope Valley, including the Antelope Valley California Poppy Reserve. The data used to create this image were acquired by SRTM aboard the Space Shuttle Endeavour, launched on February 11, 2000.

    This type of display adds the important dimension of elevation to the study of land use and environmental processes as observed in satellite images. The perspective view was created by draping a Landsat satellite image over an SRTM elevation model. Topography is exaggerated 1.5 times vertically. The Landsat image was provided by the United States Geological Survey's Earth Resources Observations Systems (EROS) Data Center, Sioux Falls, South Dakota.

    SRTM uses the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC.

    Size: Varies in a perspective view Location: 34.70 deg. North lat., 118.57 deg. West lon. Orientation: Looking Northwest Original Data Resolution: SRTM and Landsat: 30 meters (99 feet) Date Acquired: February 16, 2000

  5. The susitna glacier thrust fault: Characteristics of surface ruptures on the fault that initiated the 2002 denali fault earthquake

    USGS Publications Warehouse

    Crone, A.J.; Personius, S.F.; Craw, P.A.; Haeussler, P.J.; Staft, L.A.

    2004-01-01

    The 3 November 2002 Mw 7.9 Denali fault earthquake sequence initiated on the newly discovered Susitna Glacier thrust fault and caused 48 km of surface rupture. Rupture of the Susitna Glacier fault generated scarps on ice of the Susitna and West Fork glaciers and on tundra and surficial deposits along the southern front of the central Alaska Range. Based on detailed mapping, 27 topographic profiles, and field observations, we document the characteristics and slip distribution of the 2002 ruptures and describe evidence of pre-2002 ruptures on the fault. The 2002 surface faulting produced structures that range from simple folds on a single trace to complex thrust-fault ruptures and pressure ridges on multiple, sinuous strands. The deformation zone is locally more than 1 km wide. We measured a maximum vertical displacement of 5.4 m on the south-directed main thrust. North-directed backthrusts have more than 4 m of surface offset. We measured a well-constrained near-surface fault dip of about 19?? at one site, which is considerably less than seismologically determined values of 35??-48??. Surface-rupture data yield an estimated magnitude of Mw 7.3 for the fault, which is similar to the seismological value of Mw 7.2. Comparison of field and seismological data suggest that the Susitna Glacier fault is part of a large positive flower structure associated with northwest-directed transpressive deformation on the Denali fault. Prehistoric scarps are evidence of previous rupture of the Sustina Glacier fault, but additional work is needed to determine if past failures of the Susitna Glacier fault have consistently induced rupture of the Denali fault.

  6. Inverter Ground Fault Overvoltage Testing

    SciTech Connect

    Hoke, Andy; Nelson, Austin; Chakraborty, Sudipta; Chebahtah, Justin; Wang, Trudie; McCarty, Michael

    2015-08-12

    This report describes testing conducted at NREL to determine the duration and magnitude of transient overvoltages created by several commercial PV inverters during ground fault conditions. For this work, a test plan developed by the Forum on Inverter Grid Integration Issues (FIGII) has been implemented in a custom test setup at NREL. Load rejection overvoltage test results were reported previously in a separate technical report.

  7. New insights on Southern Coyote Creek Fault and Superstition Hills Fault

    NASA Astrophysics Data System (ADS)

    van Zandt, A. J.; Mellors, R. J.; Rockwell, T. K.; Burgess, M. K.; O'Hare, M.

    2007-12-01

    Recent field work has confirmed an extension of the southern Coyote Creek (CCF) branch of the San Jacinto fault in the western Salton trough. The fault marks the western edge of an area of subsidence caused by groundwater extraction, and field measurements suggest that recent strike-slip motion has occurred on this fault as well. We attempt to determine whether this fault connects at depth with the Superstition Hills fault (SHF) to the southeast by modeling observed surface deformation between the two faults measured by InSAR. Stacked ERS (descending) InSAR data from 1992 to 2000 is initially modeled using a finite fault in an elastic half-space. Observed deformation along the SHF and Elmore Ranch fault is modeled assuming shallow (< 5 km) creep. We test various models to explain surface deformation between the two faults.

  8. Fault growth and interactions in a multiphase rift fault network: Horda Platform, Norwegian North Sea

    NASA Astrophysics Data System (ADS)

    Duffy, Oliver B.; Bell, Rebecca E.; Jackson, Christopher A.-L.; Gawthorpe, Rob L.; Whipp, Paul S.

    2015-11-01

    Physical models predict that multiphase rifts that experience a change in extension direction between stretching phases will typically develop non-colinear normal fault sets. Furthermore, multiphase rifts will display a greater frequency and range of styles of fault interactions than single-phase rifts. Although these physical models have yielded useful information on the evolution of fault networks in map view, the true 3D geometry of the faults and associated interactions are poorly understood. Here, we use an integrated 3D seismic reflection and borehole dataset to examine a range of fault interactions that occur in a natural multiphase fault network in the northern Horda Platform, northern North Sea. In particular we aim to: i) determine the range of styles of fault interaction that occur between non-colinear faults; ii) examine the typical geometries and throw patterns associated with each of these different styles; and iii) highlight the differences between single-phase and multiphase rift fault networks. Our study focuses on a ca. 350 km2 region around the >60 km long, N-S-striking Tusse Fault, a normal fault system that was active in the Permian-Triassic and again in the Late Jurassic-to-Early Cretaceous. The Tusse Fault is one of a series of large (>1500 m throw) N-S-striking faults forming part of the northern Horda Platform fault network, which includes numerous smaller (2-10 km long), lower throw (<100 m), predominantly NW-SE-striking faults that were only active during the Late Jurassic to Early Cretaceous. We examine how the 2nd-stage NW-SE-striking faults grew, interacted and linked with the N-S-striking Tusse Fault, documenting a range of interaction styles including mechanical and kinematic isolation, abutment, retardation and reactivated relays. Our results demonstrate that: i) isolated, and abutting interactions are the most common fault interaction styles in the northern Horda Platform; ii) pre-existing faults can act as sites of nucleation for 2nd-stage faults or may form mechanical barriers to propagation; iii) the throw distribution on reactivated 1st-stage faults will be modified in a predictable manner if they are intersected or influenced by 2nd-stage faults; iv) sites of fault linkage and relay-breaching associated with the first phase of extension can act as preferential nucleation sites for 2nd-stage faults; and v) the development of fault intersections is a dynamic process, involving the gradual transition from one style to another.

  9. CONTROL AND FAULT DETECTOR CIRCUIT

    DOEpatents

    Winningstad, C.N.

    1958-04-01

    A power control and fault detectcr circuit for a radiofrequency system is described. The operation of the circuit controls the power output of a radio- frequency power supply to automatically start the flow of energizing power to the radio-frequency power supply and to gradually increase the power to a predetermined level which is below the point where destruction occurs upon the happening of a fault. If the radio-frequency power supply output fails to increase during such period, the control does not further increase the power. On the other hand, if the output of the radio-frequency power supply properly increases, then the control continues to increase the power to a maximum value. After the maximumn value of radio-frequency output has been achieved. the control is responsive to a ''fault,'' such as a short circuit in the radio-frequency system being driven, so that the flow of power is interrupted for an interval before the cycle is repeated.

  10. Fault detection using genetic programming

    NASA Astrophysics Data System (ADS)

    Zhang, Liang; B. Jack, Lindsay; Nandi, Asoke K.

    2005-03-01

    Genetic programming (GP) is a stochastic process for automatically generating computer programs. GP has been applied to a variety of problems which are too wide to reasonably enumerate. As far as the authors are aware, it has rarely been used in condition monitoring (CM). In this paper, GP is used to detect faults in rotating machinery. Featuresets from two different machines are used to examine the performance of two-class normal/fault recognition. The results are compared with a few other methods for fault detection: Artificial neural networks (ANNs) have been used in this field for many years, while support vector machines (SVMs) also offer successful solutions. For ANNs and SVMs, genetic algorithms have been used to do feature selection, which is an inherent function of GP. In all cases, the GP demonstrates performance which equals or betters that of the previous best performing approaches on these data sets. The training times are also found to be considerably shorter than the other approaches, whilst the generated classification rules are easy to understand and independently validate.

  11. Dynamic Modelling of Fault Slip Induced by Stress Waves due to Stope Production Blasts

    NASA Astrophysics Data System (ADS)

    Sainoki, Atsushi; Mitri, Hani S.

    2016-01-01

    Seismic events can take place due to the interaction of stress waves induced by stope production blasts with faults located in close proximity to stopes. The occurrence of such seismic events needs to be controlled to ensure the safety of the mine operators and the underground mine workings. This paper presents the results of a dynamic numerical modelling study of fault slip induced by stress waves resulting from stope production blasts. First, the calibration of a numerical model having a single blast hole is performed using a charge weight scaling law to determine blast pressure and damping coefficient of the rockmass. Subsequently, a numerical model of a typical Canadian metal mine encompassing a fault parallel to a tabular ore deposit is constructed, and the simulation of stope extraction sequence is carried out with static analyses until the fault exhibits slip burst conditions. At that point, the dynamic analysis begins by applying the calibrated blast pressure to the stope wall in the form of velocities generated by the blast holes. It is shown from the results obtained from the dynamic analysis that the stress waves reflected on the fault create a drop of normal stresses acting on the fault, which produces a reduction in shear stresses while resulting in fault slip. The influence of blast sequences on the behaviour of the fault is also examined assuming several types of blast sequences. Comparison of the blast sequence simulation results indicates that performing simultaneous blasts symmetrically induces the same level of seismic events as separate blasts, although seismic energy is more rapidly released when blasts are performed symmetrically. On the other hand when nine blast holes are blasted simultaneously, a large seismic event is induced, compared to the other two blasts. It is concluded that the separate blasts might be employed under the adopted geological conditions. The developed methodology and procedure to arrive at an ideal blast sequence can be applied to other mines where faults are found in the vicinity of stopes.

  12. Paleoearthquake recurrence on the East Paradise fault zone, metropolitan Albuquerque, New Mexico

    USGS Publications Warehouse

    Personius, Stephen F.; Mahan, Shannon

    2000-01-01

    A fortuitous exposure of the East Paradise fault zone near Arroyo de las Calabacillas has helped us determine a post-middle Pleistocene history for a long-forgotten Quaternary fault in the City of Albuquerque, New Mexico. Mapping of two exposures of the fault zone allowed us to measure a total vertical offset of 2.75 m across middle Pleistocene fluvial and eolian deposits and to estimate individual surface-faulting events of about 1, 0.5, and 1.25 m. These measurements and several thermoluminescence ages allow us to calculate a long-term average slip rate of 0.01 ± 0.001 mm/yr and date two surface-faulting events to 208 ± 25 ka and 75 ± 7 ka. The youngest event probably occurred in the late Pleistocene, sometime after 75 ± 7 ka. These data yield a single recurrence interval of 133 ± 26 ka and an average recurrence interval of 90 ± 10 ka. However, recurrence intervals are highly variable because the two youngest events occurred in less than 75 ka. Offsets of 0.5-1.25 m and a fault length of 13-20 km indicate that surface-rupturing paleoearthquakes on the East Paradise fault zone had probable Ms or Mw magnitudes of 6.8-7.0. Although recurrence intervals are long on the East Paradise fault zone, these data are significant because they represent some of the first published slip rate, paleoearthquake magnitude, and recurrence information for any of the numerous Quaternary faults in the rapidly growing Albuquerque-Rio Rancho metropolitan area.

  13. Data and Visualizations in the Southern California Earthquake Center's Fault Information System

    NASA Astrophysics Data System (ADS)

    Perry, S.

    2003-12-01

    The Southern California Earthquake Center's Fault Information System (FIS) provides a single point of access to fault-related data and models from multiple databases and datasets. The FIS is built of computer code, metadata and Web interfaces based on Web services technology, which enables queries and data interchange irrespective of computer software or platform. Currently we have working prototypes of programmatic and browser-based access. The first generation FIS may be searched and downloaded live, by automated processes, as well as interactively, by humans using a browser. Users get ascii data in plain text or encoded in XML. Via the Earthquake Information Technology (EIT) Interns (Juve and others, this meeting), we are also testing the effectiveness of querying multiple databases using a fault database ontology. For more than a decade, the California Geological Survey (CGS), SCEC, and the U. S. Geological Survey (USGS) have put considerable, shared resources into compiling and assessing published fault data, then providing the data on the Web. Several databases now exist, with different formats, datasets, purposes, and users, in various stages of completion. When fault databases were first envisioned, the full power of today's internet was not yet recognized, and the databases became the Web equivalents of review papers, where one could read an overview summation of a fault, then copy and paste pertinent data. Today, numerous researchers also require rapid queries and downloads of data. Consequently, the first components of the FIS are MySQL databases that deliver numeric values from earlier, text-based databases. Another essential service provided by the FIS is visualizations of fault representations such as those in SCEC's Community Fault Model. The long term goal is to provide a standardized, open-source, platform-independent visualization technique. Currently, the FIS makes available fault model viewing software for users with access to Matlab or Java3D. The latter is the interactive LA3D software of the SCEC EIT intern team, which will be demonstrated at this session.

  14. Earthquake nucleation on faults with rate-and state-dependent strength

    USGS Publications Warehouse

    Dieterich, J.H.

    1992-01-01

    Dieterich, J.H., 1992. Earthquake nucleation on faults with rate- and state-dependent strength. In: T. Mikumo, K. Aki, M. Ohnaka, L.J. Ruff and P.K.P. Spudich (Editors), Earthquake Source Physics and Earthquake Precursors. Tectonophysics, 211: 115-134. Faults with rate- and state-dependent constitutive properties reproduce a range of observed fault slip phenomena including spontaneous nucleation of slip instabilities at stresses above some critical stress level and recovery of strength following slip instability. Calculations with a plane-strain fault model with spatially varying properties demonstrate that accelerating slip precedes instability and becomes localized to a fault patch. The dimensions of the fault patch follow scaling relations for the minimum critical length for unstable fault slip. The critical length is a function of normal stress, loading conditions and constitutive parameters which include Dc, the characteristic slip distance. If slip starts on a patch that exceeds the critical size, the length of the rapidly accelerating zone tends to shrink to the characteristic size as the time of instability approaches. Solutions have been obtained for a uniform, fixed-patch model that are in good agreement with results from the plane-strain model. Over a wide range of conditions, above the steady-state stress, the logarithm of the time to instability linearly decreases as the initial stress increases. Because nucleation patch length and premonitory displacement are proportional to Dc, the moment of premonitory slip scales by D3c. The scaling of Dc is currently an open question. Unless Dc for earthquake faults is significantly greater than that observed on laboratory faults, premonitory strain arising from the nucleation process for earthquakes may by too small to detect using current observation methods. Excluding the possibility that Dc in the nucleation zone controls the magnitude of the subsequent earthquake, then the source dimensions of the smallest earthquakes in a region provide an upper limit for the size of the nucleation patch. ?? 1992.

  15. Influence of fault trend, fault bends, and fault convergence on shallow structure, geomorphology, and hazards, Hosgri strike-slip fault, offshore central California

    NASA Astrophysics Data System (ADS)

    Johnson, S. Y.; Watt, J. T.; Hartwell, S. R.

    2012-12-01

    We mapped a ~94-km-long portion of the right-lateral Hosgri Fault Zone from Point Sal to Piedras Blancas in offshore central California using high-resolution seismic reflection profiles, marine magnetic data, and multibeam bathymetry. The database includes 121 seismic profiles across the fault zone and is perhaps the most comprehensive reported survey of the shallow structure of an active strike-slip fault. These data document the location, length, and near-surface continuity of multiple fault strands, highlight fault-zone heterogeneity, and demonstrate the importance of fault trend, fault bends, and fault convergences in the development of shallow structure and tectonic geomorphology. The Hosgri Fault Zone is continuous through the study area passing through a broad arc in which fault trend changes from about 338° to 328° from south to north. The southern ~40 km of the fault zone in this area is more extensional, resulting in accommodation space that is filled by deltaic sediments of the Santa Maria River. The central ~24 km of the fault zone is characterized by oblique convergence of the Hosgri Fault Zone with the more northwest-trending Los Osos and Shoreline Faults. Convergence between these faults has resulted in the formation of local restraining and releasing fault bends, transpressive uplifts, and transtensional basins of varying size and morphology. We present a hypothesis that links development of a paired fault bend to indenting and bulging of the Hosgri Fault by a strong crustal block translated to the northwest along the Shoreline Fault. Two diverging Hosgri Fault strands bounding a central uplifted block characterize the northern ~30 km of the Hosgri Fault in this area. The eastern Hosgri strand passes through releasing and restraining bends; the releasing bend is the primary control on development of an elongate, asymmetric, "Lazy Z" sedimentary basin. The western strand of the Hosgri Fault Zone passes through a significant restraining bend and dies out northward where we propose that its slip transfers to active structures in the Piedras Blancas fold belt. Given the continuity of the Hosgri Fault Zone through our study area, earthquake hazard assessments should incorporate a minimum rupture length of 110 km. Our data do not constrain lateral slip rates on the Hosgri, which probably vary along the fault (both to the north and south) as different structures converge and diverge but are likely in the geodetically estimated range of 2 to 4 mm/yr. More focused mapping of lowstand geomorphic features (e.g., channels, paleoshorelines) has the potential to provide better constraints. The post-Last-Glacial Maximum unconformity is an important surface for constraining vertical deformation, yielding local fault offset rates that may be as high as 1.4 mm/yr and off-fault deformation rates as high as 0.5 mm/yr. These vertical rates are short-term and not sustainable over longer geologic time, emphasizing the complex evolution and dynamics of strike-slip zones.

  16. Overprinting faulting mechanisms during the development of multiple fault sets in sandstone, Chimney Rock fault array, Utah, USA

    NASA Astrophysics Data System (ADS)

    Davatzes, Nicholas C.; Aydin, Atilla; Eichhubl, Peter

    2003-02-01

    The deformation mechanisms producing the Chimney Rock normal fault array (San Rafael Swell, Utah, USA) are identified from detailed analyses of the structural components of the faults and their architecture. Faults in this area occur in four sets with oppositely dipping fault pairs striking ENE and WNW. The ENE-striking faults initially developed by formation of deformation bands and associated slip surfaces (deformation mechanism 1). After deformation band formation ceased, three sets of regional joints developed. The oldest two sets of the regional joints, including the most prominent WNW-striking set, were sheared. Localized deformation due to shearing of the WNW-striking regional joints formed WNW-striking map-scale normal faults. The formation mechanism of these faults can be characterized by the shearing of joints that produces splay joints, breccia, and eventually a core of fault rock (deformation mechanism 2). During this second phase of faulting, the ENE-striking faults were reactivated by shear across the slip surfaces and shearing of ENE-striking joints, producing localized splay joints and breccia (similar to deformation mechanism 2) superimposed onto a dense zone of deformation bands from the first phase. We found that new structural components are added to a fault zone as a function of increasing offset for both deformation mechanisms. Conversely, we estimated the magnitude of slip partitioned by the two mechanisms using the fault architecture and the component structures. Our analyses demonstrate that faults in a single rock type and location, with similar length and offset, but forming at different times and under different loading conditions, can have fundamentally different fault architecture. The impact by each mechanism on petrophysical properties of the fault is different. Deformation mechanism 1 produces deformations bands that can act as fluid baffles, whereas deformation mechanism 2 results in networks of joints and breccia that can act as preferred fluid conduits. Consequently, a detailed analysis of fault architecture is essential for establishing an accurate tectonic history, deformation path, and hydraulic properties of a faulted terrain.

  17. Building the GEM Faulted Earth database

    NASA Astrophysics Data System (ADS)

    Litchfield, N. J.; Berryman, K. R.; Christophersen, A.; Thomas, R. F.; Wyss, B.; Tarter, J.; Pagani, M.; Stein, R. S.; Costa, C. H.; Sieh, K. E.

    2011-12-01

    The GEM Faulted Earth project is aiming to build a global active fault and seismic source database with a common set of strategies, standards, and formats, to be placed in the public domain. Faulted Earth is one of five hazard global components of the Global Earthquake Model (GEM) project. A key early phase of the GEM Faulted Earth project is to build a database which is flexible enough to capture existing and variable (e.g., from slow interplate faults to fast subduction interfaces) global data, and yet is not too onerous to enter new data from areas where existing databases are not available. The purpose of this talk is to give an update on progress building the GEM Faulted Earth database. The database design conceptually has two layers, (1) active faults and folds, and (2) fault sources, and automated processes are being defined to generate fault sources. These include the calculation of moment magnitude using a user-selected magnitude-length or magnitude-area scaling relation, and the calculation of recurrence interval from displacement divided by slip rate, where displacement is calculated from moment and moment magnitude. The fault-based earthquake sources defined by the Faulted Earth project will then be rationalised with those defined by the other GEM global components. A web based tool is being developed for entering individual faults and folds, and fault sources, and includes capture of additional information collected at individual sites, as well as descriptions of the data sources. GIS shapefiles of individual faults and folds, and fault sources will also be able to be uploaded. A data dictionary explaining the database design rationale, definitions of the attributes and formats, and a tool user guide is also being developed. Existing national databases will be uploaded outside of the fault compilation tool, through a process of mapping common attributes between the databases. Regional workshops are planned for compilation in areas where existing databases are not available, or require further population, and will include training on using the fault compilation tool. The tool is also envisaged as an important legacy of the GEM Faulted Earth project, to be available for use beyond the end of the 2 year project.

  18. Fault tolerant operation of switched reluctance machine

    NASA Astrophysics Data System (ADS)

    Wang, Wei

    The energy crisis and environmental challenges have driven industry towards more energy efficient solutions. With nearly 60% of electricity consumed by various electric machines in industry sector, advancement in the efficiency of the electric drive system is of vital importance. Adjustable speed drive system (ASDS) provides excellent speed regulation and dynamic performance as well as dramatically improved system efficiency compared with conventional motors without electronics drives. Industry has witnessed tremendous grow in ASDS applications not only as a driving force but also as an electric auxiliary system for replacing bulky and low efficiency auxiliary hydraulic and mechanical systems. With the vast penetration of ASDS, its fault tolerant operation capability is more widely recognized as an important feature of drive performance especially for aerospace, automotive applications and other industrial drive applications demanding high reliability. The Switched Reluctance Machine (SRM), a low cost, highly reliable electric machine with fault tolerant operation capability, has drawn substantial attention in the past three decades. Nevertheless, SRM is not free of fault. Certain faults such as converter faults, sensor faults, winding shorts, eccentricity and position sensor faults are commonly shared among all ASDS. In this dissertation, a thorough understanding of various faults and their influence on transient and steady state performance of SRM is developed via simulation and experimental study, providing necessary knowledge for fault detection and post fault management. Lumped parameter models are established for fast real time simulation and drive control. Based on the behavior of the faults, a fault detection scheme is developed for the purpose of fast and reliable fault diagnosis. In order to improve the SRM power and torque capacity under faults, the maximum torque per ampere excitation are conceptualized and validated through theoretical analysis and experiments. With the proposed optimal waveform, torque production is greatly improved under the same Root Mean Square (RMS) current constraint. Additionally, position sensorless operation methods under phase faults are investigated to account for the combination of physical position sensor and phase winding faults. A comprehensive solution for position sensorless operation under single and multiple phases fault are proposed and validated through experiments. Continuous position sensorless operation with seamless transition between various numbers of phase fault is achieved.

  19. Delineating a shallow fault zone and dipping bed rock strata using multichannal analysis of surface waves with a land streamer

    USGS Publications Warehouse

    Ivanov, J.; Miller, R.D.; Lacombe, P.; Johnson, C.D.; Lane, J.W., Jr.

    2006-01-01

    The multichannel analysis of surface waves (MASW) seismic method was used to delineate a fault zone and gently dipping sedimentary bedrock at a site overlain by several meters of regolith. Seismic data were collected rapidly and inexpensively using a towed 30-channel land streamer and a rubberband-accelerated weight-drop seismic source. Data processed using the MASW method imaged the subsurface to a depth of about 20 m and allowed detection of the overburden, gross bedding features, and fault zone. The fault zone was characterized by a lower shear-wave velocity (Vs) than the competent bedrock, consistent with a large-scale fault, secondary fractures, and in-situ weathering. The MASW 2D Vs section was further interpreted to identify dipping beds consistent with local geologic mapping. Mapping of shallow-fault zones and dipping sedimentary rock substantially extends the applications of the MASW method. ?? 2006 Society of Exploration Geophysicists.

  20. A Log-Scaling Fault Tolerant Agreement Algorithm for a Fault Tolerant MPI

    SciTech Connect

    Hursey, Joshua J; Naughton, III, Thomas J; Vallee, Geoffroy R; Graham, Richard L

    2011-01-01

    The lack of fault tolerance is becoming a limiting factor for application scalability in HPC systems. The MPI does not provide standardized fault tolerance interfaces and semantics. The MPI Forum's Fault Tolerance Working Group is proposing a collective fault tolerant agreement algorithm for the next MPI standard. Such algorithms play a central role in many fault tolerant applications. This paper combines a log-scaling two-phase commit agreement algorithm with a reduction operation to provide the necessary functionality for the new collective without any additional messages. Error handling mechanisms are described that preserve the fault tolerance properties while maintaining overall scalability.

  1. A Quaternary Fault Database for Central Asia

    NASA Astrophysics Data System (ADS)

    Mohadjer, S.; Ehlers, T. A.; Bendick, R.; Stübner, K.; Strube, T.

    2015-09-01

    Earthquakes represent the highest risk in terms of potential loss of lives and economic damage for Central Asian countries. Knowledge of fault location and behavior is essential in calculating and mapping seismic hazard. Previous efforts in compiling fault information for Central Asia have generated a large amount of data that are published in limited-access journals with no digital maps publicly available, or are limited in their description of important fault parameters such as slip rates. This study builds on previous work by improving access to fault information through a web-based interactive map and an online database with search capabilities that allow users to organize data by different fields. The data presented in this compilation include fault location, its geographic, seismic and structural characteristics, short descriptions, narrative comments and references to peer-reviewed publications. The interactive map displays 1196 fault segments and 34 000 earthquake locations on a shaded-relief map. The online database contains attributes for 122 faults mentioned in the literature, with Quaternary and geodetic slip rates reported for 38 and 26 faults respectively, and earthquake history reported for 39 faults. This work has implications for seismic hazard studies in Central Asia as it summarizes important fault parameters, and can reduce earthquake risk by enhancing public access to information. It also allows scientists and hazard assessment teams to identify structures and regions where data gaps exist and future investigations are needed.

  2. Neotectonics of Panama. I. Major fault systems

    SciTech Connect

    Corrigan, J.; Mann, P.

    1985-01-01

    The direction and rate of relative plate motion across the Caribbean-Nazca boundary in Panama is poorly known. This lack of understanding can be attributed to diffuse seismicity; lack of well constrained focal mechanisms from critical areas; and dense tropical vegetation. In order to better understand the relation of plate motions to major fault systems in Panama, the authors have integrated geologic, remote sensing, earthquake and UTIG marine seismic reflection data. Three areas of recent faulting can be distinguished in Panama and its shelf areas; ZONE 1 of eastern Panama consists of a 70 km wide zone of 3 discrete left-lateral strike-slip faults (Sanson Hills, Jaque River, Sambu) which strike N40W and can be traced as continuous features for distances of 100-150 km; ZONE 2 in central Panama consists of a diffuse zone of discontinuous normal(.) faults which range in strike from N40E, N70E; ZONE 3 in western Panama consists of a 60 km wide zone of 2 discrete, left-lateral(.) strike-slip faults which strike N60W and can be traced as continuous features for distances of 150 km; ZONE 3 faults appear to be continuous with faults bounding the forearc Teraba Trough of Costa Rica. The relation of faults of ZONE 3 to faults of ZONE 2 and a major fault bounding the southern Panama shelf is unclear.

  3. Determining Fault Orientation with Sagnac Interferometers

    NASA Astrophysics Data System (ADS)

    Gruenwald, Konstantin; Dunn, Robert

    2014-03-01

    Typically, earthquake fault ruptures emit seismic waves in directions dependent on the fault's orientation. Specifically, as the fault slips to release strain, compressional P-waves propagate parallel and perpendicular to the fault plane, and transverse S-waves propagate at 45 degree angles to the fault-a result of the double-couple model of fault slippage. Sagnac Interferometers (ring-lasers) have been used to study wave components of several natural phenomena. We used the initial responses of a ring-laser from transverse S-waves to determine the orientation of the nearby Guy/Greenbrier fault, the source of an earthquake swarm in 2010-11 purportedly caused by hydraulic fracturing. This orientation was compared to the structure of the fault extracted by nearby seismogram responses. Our goal was to determine if ring-lasers could reinforce or add to the models of fault orientation constructed from seismographs. The results indicate that the ring-laser's responses can aid in constructing fault orientation in a manner similar to traditional seismographs. Funded by the Arkansas Space Grant Consortium and the National Science Foundation.

  4. DEM simulation of growth normal fault slip

    NASA Astrophysics Data System (ADS)

    Chu, Sheng-Shin; Lin, Ming-Lang; Nien, Wie-Tung; Chan, Pei-Chen

    2014-05-01

    Slip of the fault can cause deformation of shallower soil layers and lead to the destruction of infrastructures. Shanchiao fault on the west side of the Taipei basin is categorized. The activities of Shanchiao fault will cause the quaternary sediments underneath the Taipei basin to become deformed. This will cause damage to structures, traffic construction, and utility lines within the area. It is determined from data of geological drilling and dating, Shanchiao fault has growth fault. In experiment, a sand box model was built with non-cohesive sand soil to simulate the existence of growth fault in Shanchiao Fault and forecast the effect on scope of shear band development and ground differential deformation. The results of the experiment showed that when a normal fault containing growth fault, at the offset of base rock the shear band will develop upward along with the weak side of shear band of the original topped soil layer, and this shear band will develop to surface much faster than that of single top layer. The offset ratio (basement slip / lower top soil thickness) required is only about 1/3 of that of single cover soil layer. In this research, it is tried to conduct numerical simulation of sand box experiment with a Discrete Element Method program, PFC2D, to simulate the upper covering sand layer shear band development pace and scope of normal growth fault slip. Results of simulation indicated, it is very close to the outcome of sand box experiment. It can be extended to application in water pipeline project design around fault zone in the future. Keywords: Taipei Basin, Shanchiao fault, growth fault, PFC2D

  5. Perspective View, San Andreas Fault

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The prominent linear feature straight down the center of this perspective view is the San Andreas Fault in an image created with data from NASA's shuttle Radar Topography Mission (SRTM), which will be used by geologists studying fault dynamics and landforms resulting from active tectonics. This segment of the fault lies west of the city of Palmdale, California, about 100 kilometers (about 60 miles) northwest of Los Angeles. The fault is the active tectonic boundary between the North American plate on the right, and the Pacific plate on the left. Relative to each other, the Pacific plate is moving away from the viewer and the North American plate is moving toward the viewer along what geologists call a right lateral strike-slip fault. This area is at the junction of two large mountain ranges, the San Gabriel Mountains on the left and the Tehachapi Mountains on the right. Quail Lake Reservoir sits in the topographic depression created by past movement along the fault. Interstate 5 is the prominent linear feature starting at the left edge of the image and continuing into the fault zone, passing eventually over Tejon Pass into the Central Valley, visible at the upper left.

    This type of display adds the important dimension of elevation to the study of land use and environmental processes as observed in satellite images. The perspective view was created by draping a Landsat satellite image over an SRTM elevation model. Topography is exaggerated 1.5 times vertically. The Landsat image was provided by the United States Geological Survey's Earth Resources Observations Systems (EROS) Data Center, Sioux Falls, South Dakota.

    Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11,2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise,Washington, DC.

    Size: Varies in a perspective view Location: 34.78 deg. North lat., 118.75 deg. West lon. Orientation: Looking Northwest Original Data Resolution: SRTM and Landsat: 30 meters (99 feet) Date Acquired: February 16, 2000

  6. The Earthquake Loading Cycle and the Deep Structure of the North Anatolian Fault

    NASA Astrophysics Data System (ADS)

    Wright, Tim; Cornwell, David; Farrell, Katie; Houseman, Greg; Hussain, Ekbal; Llloyd, Geoffrey; Phillips, Richard; Thompson, David; Rost, Sebastian; Yamasaki, Tadashi; Turkelli, Niyazi; Gulen, Levent

    2014-05-01

    Deformation of the Earth's upper crust is localised onto narrow fault zones, which may slip suddenly and catastrophically in earthquakes. Strain in the upper mantle is more broadly distributed and is typically thought to occur by continuous ductile creep. The transition in the lower crust from broad shear zone to a narrow structure in the upper crust is poorly understood but the properties of the lower crust are an important control on the behaviour of the system during the earthquake loading cycle. The properties of lower crustal rocks, and their spatial variation, cannot be measured directly; instead inferences are typically made from seismic observations, exhumed geological analogues, and modelling of surface deformation data. Existing seismic experiments have poor resolution in the lower crust; and current geodetic models do not reproduce observations of rapid post-seismic and focussed inter-seismic strain. Here we present the preliminary findings of FaultLab, an interdisciplinary experiment using seismic imaging, geodesy, numerical modelling, and geology to investigate how the earthquake loading cycle of the North Anatolian Fault Zone is controlled by its deep crustal structure. We present results from an 18 month deployment of a 73 station network encompassing the northern and southern branches of the NAFZ in the Sakarya region. The dense array (nominal station station spacing of 7 km) crosses the 1999 Izmit earthquake rupture and is designed to provide high resolution images of the mid-lower crust. Teleseismic scattering tomography and receiver function analysis suggest that the two branches of the fault remain as relatively narrow structures to at least 20 km, and that the faults separate very different terranes. This portion of the North Anatolian Fault has the best geodetic record for any strike-slip fault, with deformation well recorded both before and after the 1999 earthquakes. Prior to the earthquake, strain was focused in a ~50 km region around the fault. Following the earthquake, a rapid post-seismic transient was observed, which slowly decayed over the subsequent decade. Viscoelastic modelling requires materials with at least two relaxation time constants to explain these observations - a strong material to allow focused interseismic strain, and a weak material to give rapid postseismic deformation. Geological analogues of the mid-lower crust beneath the North Anatolian Fault are consistent with the idea that strain is focused in relatively narrow shear zones. We present a shear-zone model for the earthquake deformation cycle that is consistent with these interdisciplinary observations, and discuss the implications for other fault zones.

  7. Dynamic Modeling of Coseismic Rupture on Partially-Creeping Strike-Slip Faults

    NASA Astrophysics Data System (ADS)

    Lozos, J.; Funning, G.; Oglesby, D. D.

    2013-12-01

    Partially creeping faults exhibit complex behavior in terms of which parts of the fault slip seismically versus aseismically; this complexity is both temporal and spatial. Several faults in California exhibit creep that is rapid enough to be detected geodetically using InSAR, GPS and near-field methods, such as theodolite measurements of alignment arrays. Such studies of the Hayward Fault in the San Francisco Bay Area suggest that it has a complex pattern of creeping and locked patches along strike and down dip. The spatial pattern of creeping versus locked zones may have as much of an effect on throughgoing rupture as the more general presence of creep does. We use the 3D finite element modeling code FaultMod to conduct single-cycle models of dynamic rupture on partially creeping strike slip faults, in order to determine whether coseismic rupture can propagate into creeping regions, and how the presence and distribution of creep affects the ability of rupture to propagate along strike. We implement a rate-state friction criterion, in which locked zones of the fault are represented by rate-weakening behavior, and creeping zones of the fault are assigned rate-strengthening properties. We model two simplified partial creep geometries: a locked patch at the base of a largely creeping fault (similar to what is inferred for the Hayward Fault), and a creeping patch at the surface of a predominantly locked fault (similar to what is inferred for the Rodgers Creek Fault). We find that, in the case of a locked patch within a creeping fault, rupture does not propagate more than a kilometer past the edges of the locked patch, regardless of the patch radius. The case of a creeping patch within a locked fault is more complicated. We find that the width of the locked areas around the creeping patch determine whether or not rupture is able to propagate around the creeping patch and along the full strike of the fault; if the width of locked zone between the edge of the creeping patch and the end of the fault is too narrow, rupture is arrested. Regardless of along strike extent, rupture is able to penetrate several kilometers into the creeping patch, or all the way through it in the case of smaller patch radii, though at a slower rate than in the locked parts of the fault. By imposing multiple creeping and locked patches on a realistically complex fault geometry, we expect to be able to estimate the spatial and temporal distribution of coseismic slip on a partially creeping fault. We believe that combining the results of such dynamic models with static models of interseismic and postseismic creep may allow us to extend our slip estimates to cover the full earthquake cycle.

  8. The evolution of fabric with displacement in natural brittle faults

    NASA Astrophysics Data System (ADS)

    Mittempergher, S.; Di Toro, G.; Gratier, J.; Aretusini, S.; Boullier-Bertrand, A.

    2011-12-01

    In experiments performed at room temperature on gouges, a characteristic clast size distribution (CSD) is produced with increasing strain, and shear localization is documented to begin after few millimetres of sliding. But in natural faults active at depth in the crust, mechanical processes are associated with fluid-rock interactions, which might control the deformation and strength recovery. We aim to investigate the microstructural, geochemical and mineralogical evolution of low-displacement faults with increasing shear strain. The faults (cataclasite- and pseudotachylyte-bearing) are hosted in tonalite and were active at 9-11 km and 250-300°C. The samples were collected on a large glacier-polished outcrop, where major faults (accommodating up to 4300 mm of displacement) exploit pre-existing magmatic joints and are connected by a network of secondary fractures and faults (accommodating up to 500 mm of displacement) breaking intact tonalite. We performed optical and cathodoluminescence (CL) microscope, Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDS), Rietveld X-Ray Powder Diffraction and microprobe chemical analysis in deformation zones of secondary faults with various offsets in order to evaluate the transfer of chemical species between dissolution zones and protected zones. Image analysis techniques were applied on SEM-BSE and optical microscope images to compute the CSD in samples, which experienced an increasing amount of strain. The secondary fractures are up to 5 mm thick. Within the first 20 mm of displacement, shear localizes along Y and R1 surfaces and a cataclastic foliation develops. The CSD evolves from a fractal dimension D of 1.3 in fractures without visible displacement to values above 2 after the first 500 mm of displacement. Chemical maps and CL images indicate that the foliation in cataclasite results from the rotation and fragmentation of clasts, with dissolution of quartz and passive concentration of Ti oxides and titanite in the foliation planes. The cataclasites are cemented by pervasive precipitation of K-feldspar plagues and idiomorphic, randomly oriented, epidote and chlorite. We conclude that the textures of these small displacement (< 500 mm) faults are controlled by brittle processes (fracture propagation and cataclastic comminution) similar to those reproduced in friction experiments performed on granite gouge (e.g., Beeler et al., 1996; Logan, 2007). Then progressively, stress driven fluid-rock reactions develop as fracturing and grain size reduction allows the kinetics of these reactions to be more efficient and fracture interconnection allows fluid infiltration. Healing of microfractures and fault rock cementation caused a rapid posteismic recovery of fault strength. References Beeler, N.M., Tullis, T.E., Blanpied, L., Weeks, J.D., 1996. Frictional behaviour of large displacement experimental faults. Journal of Geophysical Research 101, B4, 8697-8715. Logan, J.M., 2007. The progression from damage to localization of displacement observed in laboratory testing of porous rocks, in Lewis, H., and Couples, G.D. (eds.) The relationship between damage and localization. Geological Society of London Special Publication 289, 75-87.

  9. Modelling evolving fault zones: Fragmentation processes, products and potential implications

    NASA Astrophysics Data System (ADS)

    Mair, K.; Abe, S.

    2011-12-01

    Exhumed fault rocks display a wide variety of textural fabrics whose signatures may provide clues to the deformation processes operating during a fault's life. In an active fault, the products of intense fracturing or the development of strong fabrics can themselves be game changers in terms of macroscopic mechanical behaviour. Here we investigate the fragmentation processes operating in evolving faults during shear and the signatures they leave behind, using a numerical model. We consider: (i) what drives the production and evolution of granular debris commonly found along faults; (ii) the nature of the fragmentation products; and (iii) the potential influence of these features on subsequent sliding. Our discrete element (DEM) 3D fault gouge fragmentation models consist of aggregate grains, composed of several thousand spherical particles stuck together with breakable elastic bonds. The aggregate grains are confined between rough fault walls that can themselves potentially breakup leading to fault roughness evolution. During shear, under a given normal stress, the aggregate gouge grains can fragment and evolve in a somewhat natural way. The grain breakage in our models appears to be driven by two distinct comminution mechanisms: grain splitting and grain abrasion. The relative importance of these mechanisms changes with the applied normal stress, the accumulated slip and the boundary roughness in the model. Grain splitting contributes significantly to comminution at higher normal stresses, particularly during the initial stages of simulations. Conversely, grain abrasion prevails at lower normal stresses and is the main comminution mechanism operating in the later stages of all simulations. In terms of fragmentation products, the different mechanisms generate distinct grain size distributions. Grain splitting rapidly generates a power law size distribution, whereas grain abrasion (acting alone) tends to produce a bimodal size distribution (lacking intermediate sized grains). We suggest that the apparent transition from mainly grain splitting to abrasion with accumulated slip is driven by the changing internal local stress network associated with the evolving grain size distribution itself. Although, grain splitting may be more efficient in reducing mean grain size, we show that grain abrasion can potentially produce accumulations of fine material and will likely round the larger 'survivor' grains. We know that grain size and shape distributions affect sliding friction, thus both these processes could affect sliding behaviour and could do so at relatively low stresses where major grain fragmentation might not be expected. We anticipate that the different mechanisms operating in our models could potentially govern the deformation operating at different stages of a fault's evolution. The textural signatures produced (e.g. changes in grain size and shape distributions) could potentially affect macroscopic sliding behaviour as well as controlling subsequent comminution. Importantly, such processes could lead to quite distinct mechanical effects at different normal stresses (in some cases much lower stresses than expected) and for different accumulated fault slips.

  10. Off-fault tip splay networks: A genetic and generic property of faults indicative of their long-term propagation

    NASA Astrophysics Data System (ADS)

    Perrin, Clément; Manighetti, Isabelle; Gaudemer, Yves

    2016-01-01

    We use fault maps and fault propagation evidences available in the literature to examine geometrical relations between parent faults and off-fault splays. The population includes 47 worldwide crustal faults with lengths from millimetres to thousands of kilometres and of different slip modes. We show that fault splays form adjacent to any propagating fault tip, whereas they are absent at non-propagating fault ends. Independent of fault length, slip mode, context, etc., tip splay networks have a similar fan shape widening in direction of long-term propagation, a similar relative length and width (∼ 30 and ∼ 10% of parent fault length, respectively), and a similar range of mean angles to parent fault (10-20°). We infer that tip splay networks are a genetic and a generic property of faults indicative of their long-term propagation. Their generic geometrical properties suggest they result from generic off-fault stress distribution at propagating fault ends.

  11. Software reliability through fault-avoidance and fault-tolerance

    NASA Technical Reports Server (NTRS)

    Vouk, Mladen A.; Mcallister, David F.

    1990-01-01

    The use of back-to-back, or comparison, testing for regression test or porting is examined. The efficiency and the cost of the strategy is compared with manual and table-driven single version testing. Some of the key parameters that influence the efficiency and the cost of the approach are the failure identification effort during single version program testing, the extent of implemented changes, the nature of the regression test data (e.g., random), and the nature of the inter-version failure correlation and fault-masking. The advantages and disadvantages of the technique are discussed, together with some suggestions concerning its practical use.

  12. Paleomagnetic Data From the Rinconada Fault in Central California: Evidence for Off-fault Deformation

    NASA Astrophysics Data System (ADS)

    Crump, S.; Titus, S.; McGuire, Z.; Housen, B. A.

    2009-12-01

    The Rinconada fault is one of three major sub-parallel faults of the San Andreas fault system in central California. The fault has 18 km of dextral displacement since the Pliocene and up to 60 km of total displacement for the Tertiary. A fold and thrust best is well developed in Miocene and younger sedimentary rocks on either side of the Rinconada fault. We sampled ~150 sites from the Miocene Monterey Formation within this fold and thrust belt, a unit that is often used in regional paleomagnetic studies. The sites were located within 15 km of the fault trace along a segment of the Rinconada fault that stretches from Greenfield to Paso Robles. Because this unit was deposited while the San Andreas fault system was active at this latitude, any deformation recorded by these rocks is related to plate boundary deformation. Unlike the large (>90°) rotations observed in the Transverse Ranges to the south, vertical axis rotations adjacent to the Rinconada fault are smaller (<15°) and vary with distance from the fault as well as along strike. Thus, the model for rotations from the Transverse Ranges, where large fault-bound panels rotate within a system of conjugate strike-slip faults, does not apply for this region in central California. Instead, we believe rotations occur in small fault blocks and the magnitude of rotation may be affected by local parameters such as fault geometries, specific rock types, and structural complexities. One implication of these vertical axis rotations adjacent to the Riconada fault is that off-fault regions are accommodating some of the fault-parallel plate motion. This is important for our understanding of the partitioning of plate boundary deformation in California.

  13. Fault geometries in basement-induced wrench faulting under different initial stress states

    NASA Astrophysics Data System (ADS)

    Naylor, M. A.; Mandl, G.; Supesteijn, C. H. K.

    Scaled sandbox experiments were used to generate models for relative ages, dip, strike and three-dimensional shape of faults in basement-controlled wrench faulting. The basic fault sequence runs from early en échelon Riedel shears and splay faults through 'lower-angle' shears to P shears. The Riedel shears are concave upwards and define a tulip structure in cross-section. In three dimensions, each Riedel shear has a helicoidal form. The sequence of faults and three-dimensional geometry are rationalized in terms of the prevailing stress field and Coulomb-Mohr theory of shear failure. The stress state in the sedimentary overburden before wrenching begins has a substantial influence on the fault geometries and on the final complexity of the fault zone. With the maximum compressive stress (∂ 1) initially parallel to the basement fault (transtension), Riedel shears are only slightly en échelon, sub-parallel to the basement fault, steeply dipping with a reduced helicoidal aspect. Conversely, with ∂ 1 initially perpendicular to the basement fault (transpression), Riedel shears are strongly oblique to the basement fault strike, have lower dips and an exaggerated helicoidal form; the final fault zone is both wide and complex. We find good agreement between the models and both mechanical theory and natural examples of wrench faulting.

  14. Surface faulting along the Superstition Hills fault zone and nearby faults associated with the earthquakes of 24 November 1987

    USGS Publications Warehouse

    Sharp, R.V.

    1989-01-01

    The M6.2 Elmore Desert Ranch earthquake of 24 November 1987 was associated spatially and probably temporally with left-lateral surface rupture on many northeast-trending faults in and near the Superstition Hills in western Imperial Valley. Three curving discontinuous principal zones of rupture among these breaks extended northeastward from near the Superstition Hills fault zone as far as 9km; the maximum observed surface slip, 12.5cm, was on the northern of the three, the Elmore Ranch fault, at a point near the epicenter. Twelve hours after the Elmore Ranch earthquake, the M6.6 Superstition Hills earthquake occurred near the northwest end of the right-lateral Superstition Hills fault zone. We measured displacements over 339 days at as many as 296 sites along the Superstition Hills fault zone, and repeated measurements at 49 sites provided sufficient data to fit with a simple power law. The overall distributions of right-lateral displacement at 1 day and the estimated final slip are nearly symmetrical about the midpoint of the surface rupture. The average estimated final right-lateral slip for the Superstition Hills fault zone is ~54cm. The average left-lateral slip for the conjugate faults trending northeastward is ~23cm. The southernmost ruptured member of the Superstition Hills fault zone, newly named the Wienert fault, extends the known length of the zone by about 4km. -from Authors

  15. Networking of Near Fault Observatories in Europe

    NASA Astrophysics Data System (ADS)

    Vogfjörd, Kristín; Bernard, Pascal; Chiraluce, Lauro; Fäh, Donat; Festa, Gaetano; Zulficar, Can

    2014-05-01

    Networking of six European near-fault observatories (NFO) was established In the FP7 infrastructure project NERA (Network of European Research Infrastructures for Earthquake Risk Assessment and Mitigation). This networking has included sharing of expertise and know-how among the observatories, distribution of analysis tools and access to data. The focus of the NFOs is on research into the active processes of their respective fault zones through acquisition and analysis of multidisciplinary data. These studies include the role of fluids in fault initiation, site effects, derived processes such as earthquake generated tsunamis and landslides, mapping the internal structure of fault systems and development of automatic early warning systems. The six fault zones are in different tectonic regimes: The South Iceland Seismic Zone (SISZ) in Iceland, the Marmara Sea in Turkey and the Corinth Rift in Greece are at plate boundaries, with strike-slip faulting characterizing the SISZ and the Marmara Sea, while normal faulting dominates in the Corinth Rift. The Alto Tiberina and Irpinia faults, dominated by low- and medium-angle normal faulting, respectively are in the Apennine mountain range in Italy and the Valais Region, characterized by both strike-slip and normal faulting is located in the Swiss Alps. The fault structures range from well-developed long faults, such as in the Marmara Sea, to more complex networks of smaller, book-shelf faults such as in the SISZ. Earthquake hazard in the fault zones ranges from significant to substantial. The Marmara Sea and Corinth rift are under ocean causing additional tsunami hazard and steep slopes and sediment-filled valleys in the Valais give rise to hazards from landslides and liquefaction. Induced seismicity has repeatedly occurred in connection with geothermal drilling and water injection in the SISZ and active volcanoes flanking the SISZ also give rise to volcanic hazard due to volcano-tectonic interaction. Organization among the NERA NFO's has led to their gaining working-group status in EPOS as the WG on Near Fault Observatories, representing multidisciplinary research of faults and fault zones.

  16. Mantle convection with plates and mobile, faulted plate margins.

    PubMed

    Zhong, S; Gurnis, M

    1995-02-10

    A finite-element formulation of faults has been incorporated into time-dependent models of mantle convection with realistic rheology, continents, and phase changes. Realistic tectonic plates naturally form with self-consistent coupling between plate and mantle dynamics. After the initiation of subduction, trenches rapidly roll back with subducted slabs temporarily laid out along the base of the transition zone. After the slabs have penetrated into the lower mantle, the velocity of trench migration decreases markedly. The inhibition of slab penetration into the lower mantle by the 670-kilometer phase change is greatly reduced in these models as compared to models without tectonic plates. PMID:17813909

  17. Intrabasinal faulting in Cretaceous forearc basins of Baja California, Mexico

    SciTech Connect

    Busby-Spera, C.; Smith, D.; Morris, W.

    1988-01-01

    Cretaceious forearc basins in Baja California show abundant evidence of intrabasinal faulting. This resulted in (1) growth of fan deltas on the margins of intrabasinal horst blocks, (2) development of a submarine canyon along the axis of a half-graben, and (3) rapid, extreme fluctuations in relative sea level due to vertical tectonics. The fill of these tectonically active residual and arc massif basins is much more complex than that of the same basin types, of similar age, to the north in the Great Valley forearc basin of California.

  18. Distributed multisensor fusion for machine condition monitoring fault diagnosis

    NASA Astrophysics Data System (ADS)

    Wang, Xue; Zhao, Guohua; Xie, Xin

    2001-09-01

    This paper presents a new general framework for multisensor fusion based on a distributed detection. Parallel processing and distributed multisensor fusion, as rapidly emerging and promising technologies, provides powerful tools for solving this difficult problem, The distribution and parallelism of proposing and confirming of hypothesis in condition and diagnostic is prosed. A combination serial and parallel reconfiguration of n sensors for decision fusion is analyzed. It shows the result for a real-time parallel distributed complex machine condition monitor and fault diagnostic system.

  19. In-circuit fault injector user's guide

    NASA Technical Reports Server (NTRS)

    Padilla, Peter A.

    1987-01-01

    A fault injector system, called an in-circuit injector, was designed and developed to facilitate fault injection experiments performed at NASA-Langley's Avionics Integration Research Lab (AIRLAB). The in-circuit fault injector (ICFI) allows fault injections to be performed on electronic systems without special test features, e.g., sockets. The system supports stuck-at-zero, stuck-at-one, and transient fault models. The ICFI system is interfaced to a VAX-11/750 minicomputer. An interface program has been developed in the VAX. The computer code required to access the interface program is presented. Also presented is the connection procedure to be followed to connect the ICFI system to a circuit under test and the ICFI front panel controls which allow manual control of fault injections.

  20. Performance Analysis on Fault Tolerant Control System

    NASA Technical Reports Server (NTRS)

    Shin, Jong-Yeob; Belcastro, Christine

    2005-01-01

    In a fault tolerant control (FTC) system, a parameter varying FTC law is reconfigured based on fault parameters estimated by fault detection and isolation (FDI) modules. FDI modules require some time to detect fault occurrences in aero-vehicle dynamics. In this paper, an FTC analysis framework is provided to calculate the upper bound of an induced-L(sub 2) norm of an FTC system with existence of false identification and detection time delay. The upper bound is written as a function of a fault detection time and exponential decay rates and has been used to determine which FTC law produces less performance degradation (tracking error) due to false identification. The analysis framework is applied for an FTC system of a HiMAT (Highly Maneuverable Aircraft Technology) vehicle. Index Terms fault tolerant control system, linear parameter varying system, HiMAT vehicle.

  1. Holocene fault scarps near Tacoma, Washington, USA

    USGS Publications Warehouse

    Sherrod, B.L.; Brocher, T.M.; Weaver, C.S.; Bucknam, R.C.; Blakely, R.J.; Kelsey, H.M.; Nelson, A.R.; Haugerud, R.

    2004-01-01

    Airborne laser mapping confirms that Holocene active faults traverse the Puget Sound metropolitan area, northwestern continental United States. The mapping, which detects forest-floor relief of as little as 15 cm, reveals scarps along geophysical lineaments that separate areas of Holocene uplift and subsidence. Along one such line of scarps, we found that a fault warped the ground surface between A.D. 770 and 1160. This reverse fault, which projects through Tacoma, Washington, bounds the southern and western sides of the Seattle uplift. The northern flank of the Seattle uplift is bounded by a reverse fault beneath Seattle that broke in A.D. 900-930. Observations of tectonic scarps along the Tacoma fault demonstrate that active faulting with associated surface rupture and ground motions pose a significant hazard in the Puget Sound region.

  2. Fault-tolerant dynamic task graph scheduling

    SciTech Connect

    Kurt, Mehmet C.; Krishnamoorthy, Sriram; Agrawal, Kunal; Agrawal, Gagan

    2014-11-16

    In this paper, we present an approach to fault tolerant execution of dynamic task graphs scheduled using work stealing. In particular, we focus on selective and localized recovery of tasks in the presence of soft faults. We elicit from the user the basic task graph structure in terms of successor and predecessor relationships. The work stealing-based algorithm to schedule such a task graph is augmented to enable recovery when the data and meta-data associated with a task get corrupted. We use this redundancy, and the knowledge of the task graph structure, to selectively recover from faults with low space and time overheads. We show that the fault tolerant design retains the essential properties of the underlying work stealing-based task scheduling algorithm, and that the fault tolerant execution is asymptotically optimal when task re-execution is taken into account. Experimental evaluation demonstrates the low cost of recovery under various fault scenarios.

  3. Probable origin of the Livingston Fault Zone

    NASA Astrophysics Data System (ADS)

    Monroe, Watson H.

    1991-09-01

    Most faulting in the Coastal Plain is high angle and generally normal, but the faults in the Livingston Fault Zone are all medium-angle reverse, forming a series of parallel horsts and grabens. Parallel to the fault zone are a number of phenomena all leading to the conclusion that the faults result from the solution of a late Cretaceous salt anticline by fresh groundwater, which then migrated up to the Eutaw and perhaps Tuscaloosa aquifers, causing an anomalous elongated area of highly saline water. The origin of the Livingston Fault Zone and the association of salt water in underlying aquifers is of particular importance at this time in relation to environmental concerns associated with hazardous waste management in the area.

  4. Constraints on the stress state of the San Andreas Fault with analysis based on core and cuttings from San Andreas Fault Observatory at Depth (SAFOD) drilling phases 1 and 2

    USGS Publications Warehouse

    Tembe, S.; Lockner, D.; Wong, T.-F.

    2009-01-01

    Analysis of field data has led different investigators to conclude that the San Andreas Fault (SAF) has either anomalously low frictional sliding strength (?? 0.6). Arguments for the apparent weakness of the SAF generally hinge on conceptual models involving intrinsically weak gouge or elevated pore pressure within the fault zone. Some models assert that weak gouge and/or high pore pressure exist under static conditions while others consider strength loss or fluid pressure increase due to rapid coseismic fault slip. The present paper is composed of three parts. First, we develop generalized equations, based on and consistent with the Rice (1992) fault zone model to relate stress orientation and magnitude to depth-dependent coefficient of friction and pore pressure. Second, we present temperature-and pressure-dependent friction measurements from wet illite-rich fault gouge extracted from San Andreas Fault Observatory at Depth (SAFOD) phase 1 core samples and from weak minerals associated with the San Andreas Fault. Third, we reevaluate the state of stress on the San Andreas Fault in light of new constraints imposed by SAFOD borehole data. Pure talc (?????0.1) had the lowest strength considered and was sufficiently weak to satisfy weak fault heat flow and stress orientation constraints with hydrostatic pore pressure. Other fault gouges showed a systematic increase in strength with increasing temperature and pressure. In this case, heat flow and stress orientation constraints would require elevated pore pressure and, in some cases, fault zone pore pressure in excess of vertical stress. Copyright 2009 by the American Geophysical Union.

  5. 31 CFR 29.522 - Fault.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 31 Money and Finance: Treasury 1 2014-07-01 2014-07-01 false Fault. 29.522 Section 29.522 Money... Overpayments § 29.522 Fault. (a) General rule. A debtor is considered to be at fault if he or she, or any other... requirement. (3) The following factors may affect the decision as to whether the debtor is or is not at...

  6. 31 CFR 29.522 - Fault.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 31 Money and Finance: Treasury 1 2013-07-01 2013-07-01 false Fault. 29.522 Section 29.522 Money... Overpayments § 29.522 Fault. (a) General rule. A debtor is considered to be at fault if he or she, or any other... requirement. (3) The following factors may affect the decision as to whether the debtor is or is not at...

  7. 31 CFR 29.522 - Fault.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 31 Money and Finance: Treasury 1 2010-07-01 2010-07-01 false Fault. 29.522 Section 29.522 Money... Overpayments § 29.522 Fault. (a) General rule. A debtor is considered to be at fault if he or she, or any other... requirement. (3) The following factors may affect the decision as to whether the debtor is or is not at...

  8. 31 CFR 29.522 - Fault.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 31 Money and Finance: Treasury 1 2011-07-01 2011-07-01 false Fault. 29.522 Section 29.522 Money... Overpayments § 29.522 Fault. (a) General rule. A debtor is considered to be at fault if he or she, or any other... requirement. (3) The following factors may affect the decision as to whether the debtor is or is not at...

  9. 31 CFR 29.522 - Fault.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 31 Money and Finance: Treasury 1 2012-07-01 2012-07-01 false Fault. 29.522 Section 29.522 Money... Overpayments § 29.522 Fault. (a) General rule. A debtor is considered to be at fault if he or she, or any other... requirement. (3) The following factors may affect the decision as to whether the debtor is or is not at...

  10. Hydrogen Embrittlement And Stacking-Fault Energies

    NASA Technical Reports Server (NTRS)

    Parr, R. A.; Johnson, M. H.; Davis, J. H.; Oh, T. K.

    1988-01-01

    Embrittlement in Ni/Cu alloys appears related to stacking-fault porbabilities. Report describes attempt to show a correlation between stacking-fault energy of different Ni/Cu alloys and susceptibility to hydrogen embrittlement. Correlation could lead to more fundamental understanding and method of predicting susceptibility of given Ni/Cu alloy form stacking-fault energies calculated from X-ray diffraction measurements.

  11. Fault system polarity: A matter of chance?

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    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.

  12. Fault seal analysis: Methodology and case studies

    SciTech Connect

    Badley, M.E.; Freeman, B.; Needham, D.T.

    1996-12-31

    Fault seal can arise from reservoir/non-reservoir juxtaposition or by development of fault rock of high entry-pressure. The methodology for evaluating these possibilities uses detailed seismic mapping and well analysis. A {open_quote}first-order{close_quote} seal analysis involves identifying reservoir juxtaposition areas over the fault surface, using the mapped horizons and a refined reservoir stratigraphy defined by isochores at the fault surface. The {open_quote}second-order{close_quote} phase of the analysis assesses whether the sand-sand contacts are likely to support a pressure difference. We define two lithology-dependent attributes {open_quote}Gouge Ratio{close_quote} and {open_quote}Smear Factor{close_quote}. Gouge Ratio is an estimate of the proportion of fine-grained material entrained into the fault gouge from the wall rocks. Smear Factor methods estimate the profile thickness of a ductile shale drawn along the fault zone during faulting. Both of these parameters vary over the fault surface implying that faults cannot simply be designated {open_quote}sealing{close_quote} or {open_quote}non-sealing{close_quote}. An important step in using these parameters is to calibrate them in areas where across-fault pressure differences are explicitly known from wells on both sides of a fault. Our calibration for a number of datasets shows remarkably consistent results despite their diverse settings (e.g. Brent Province, Niger Delta, Columbus Basin). For example, a Shale Gouge Ratio of c. 20% (volume of shale in the slipped interval) is a typical threshold between minimal across-fault pressure difference and significant seal.

  13. Fault seal analysis: Methodology and case studies

    SciTech Connect

    Badley, M.E.; Freeman, B.; Needham, D.T. )

    1996-01-01

    Fault seal can arise from reservoir/non-reservoir juxtaposition or by development of fault rock of high entry-pressure. The methodology for evaluating these possibilities uses detailed seismic mapping and well analysis. A [open quote]first-order[close quote] seal analysis involves identifying reservoir juxtaposition areas over the fault surface, using the mapped horizons and a refined reservoir stratigraphy defined by isochores at the fault surface. The [open quote]second-order[close quote] phase of the analysis assesses whether the sand-sand contacts are likely to support a pressure difference. We define two lithology-dependent attributes [open quote]Gouge Ratio[close quote] and [open quote]Smear Factor[close quote]. Gouge Ratio is an estimate of the proportion of fine-grained material entrained into the fault gouge from the wall rocks. Smear Factor methods estimate the profile thickness of a ductile shale drawn along the fault zone during faulting. Both of these parameters vary over the fault surface implying that faults cannot simply be designated [open quote]sealing[close quote] or [open quote]non-sealing[close quote]. An important step in using these parameters is to calibrate them in areas where across-fault pressure differences are explicitly known from wells on both sides of a fault. Our calibration for a number of datasets shows remarkably consistent results despite their diverse settings (e.g. Brent Province, Niger Delta, Columbus Basin). For example, a Shale Gouge Ratio of c. 20% (volume of shale in the slipped interval) is a typical threshold between minimal across-fault pressure difference and significant seal.

  14. Air conditioner response to transmission faults

    SciTech Connect

    Shaffer, J.W.

    1997-05-01

    This paper describes two multi-phase faults events which occurred during periods of high air conditioning use. There was a significant loss of load in these events which is attributed to air conditioner motor protection. The overall response of the transmission system is simulated using induction motor models based on the characteristics of a typical residential air conditioner compressor motor. The sensitivity of factors such as fault location, fault duration and excitation system performance is also investigated.

  15. Fault Zone Guided Wave generation on the locked, late interseismic Alpine Fault, New Zealand

    NASA Astrophysics Data System (ADS)

    Eccles, J. D.; Gulley, A. K.; Malin, P. E.; Boese, C. M.; Townend, J.; Sutherland, R.

    2015-07-01

    Fault Zone Guided Waves (FZGWs) have been observed for the first time within New Zealand's transpressional continental plate boundary, the Alpine Fault, which is late in its typical seismic cycle. Ongoing study of these phases provides the opportunity to monitor interseismic conditions in the fault zone. Distinctive dispersive seismic codas (~7-35 Hz) have been recorded on shallow borehole seismometers installed within 20 m of the principal slip zone. Near the central Alpine Fault, known for low background seismicity, FZGW-generating microseismic events are located beyond the catchment-scale partitioning of the fault indicating lateral connectivity of the low-velocity zone immediately below the near-surface segmentation. Initial modeling of the low-velocity zone indicates a waveguide width of 60-200 m with a 10-40% reduction in S wave velocity, similar to that inferred for the fault core of other mature plate boundary faults such as the San Andreas and North Anatolian Faults.

  16. Distributed bearing fault diagnosis based on vibration analysis

    NASA Astrophysics Data System (ADS)

    Dolenc, Boštjan; Boškoski, Pavle; Juričić, Đani

    2016-01-01

    Distributed bearing faults appear under various circumstances, for example due to electroerosion or the progression of localized faults. Bearings with distributed faults tend to generate more complex vibration patterns than those with localized faults. Despite the frequent occurrence of such faults, their diagnosis has attracted limited attention. This paper examines a method for the diagnosis of distributed bearing faults employing vibration analysis. The vibrational patterns generated are modeled by incorporating the geometrical imperfections of the bearing components. Comparing envelope spectra of vibration signals shows that one can distinguish between localized and distributed faults. Furthermore, a diagnostic procedure for the detection of distributed faults is proposed. This is evaluated on several bearings with naturally born distributed faults, which are compared with fault-free bearings and bearings with localized faults. It is shown experimentally that features extracted from vibrations in fault-free, localized and distributed fault conditions form clearly separable clusters, thus enabling diagnosis.

  17. Identifiability of Additive Actuator and Sensor Faults by State Augmentation

    NASA Technical Reports Server (NTRS)

    Joshi, Suresh; Gonzalez, Oscar R.; Upchurch, Jason M.

    2014-01-01

    A class of fault detection and identification (FDI) methods for bias-type actuator and sensor faults is explored in detail from the point of view of fault identifiability. The methods use state augmentation along with banks of Kalman-Bucy filters for fault detection, fault pattern determination, and fault value estimation. A complete characterization of conditions for identifiability of bias-type actuator faults, sensor faults, and simultaneous actuator and sensor faults is presented. It is shown that FDI of simultaneous actuator and sensor faults is not possible using these methods when all sensors have unknown biases. The fault identifiability conditions are demonstrated via numerical examples. The analytical and numerical results indicate that caution must be exercised to ensure fault identifiability for different fault patterns when using such methods.

  18. Software reliability through fault-avoidance and fault-tolerance

    NASA Technical Reports Server (NTRS)

    Vouk, Mladen A.; Mcallister, David F.

    1993-01-01

    Strategies and tools for the testing, risk assessment and risk control of dependable software-based systems were developed. Part of this project consists of studies to enable the transfer of technology to industry, for example the risk management techniques for safety-concious systems. Theoretical investigations of Boolean and Relational Operator (BRO) testing strategy were conducted for condition-based testing. The Basic Graph Generation and Analysis tool (BGG) was extended to fully incorporate several variants of the BRO metric. Single- and multi-phase risk, coverage and time-based models are being developed to provide additional theoretical and empirical basis for estimation of the reliability and availability of large, highly dependable software. A model for software process and risk management was developed. The use of cause-effect graphing for software specification and validation was investigated. Lastly, advanced software fault-tolerance models were studied to provide alternatives and improvements in situations where simple software fault-tolerance strategies break down.

  19. Fault rheology beyond frictional melting

    PubMed Central

    Lavallée, Yan; Hirose, Takehiro; Kendrick, Jackie E.; Hess, Kai-Uwe; Dingwell, Donald B.

    2015-01-01

    During earthquakes, comminution and frictional heating both contribute to the dissipation of stored energy. With sufficient dissipative heating, melting processes can ensue, yielding the production of frictional melts or “pseudotachylytes.” It is commonly assumed that the Newtonian viscosities of such melts control subsequent fault slip resistance. Rock melts, however, are viscoelastic bodies, and, at high strain rates, they exhibit evidence of a glass transition. Here, we present the results of high-velocity friction experiments on a well-characterized melt that demonstrate how slip in melt-bearing faults can be governed by brittle fragmentation phenomena encountered at the glass transition. Slip analysis using models that incorporate viscoelastic responses indicates that even in the presence of melt, slip persists in the solid state until sufficient heat is generated to reduce the viscosity and allow remobilization in the liquid state. Where a rock is present next to the melt, we note that wear of the crystalline wall rock by liquid fragmentation and agglutination also contributes to the brittle component of these experimentally generated pseudotachylytes. We conclude that in the case of pseudotachylyte generation during an earthquake, slip even beyond the onset of frictional melting is not controlled merely by viscosity but rather by an interplay of viscoelastic forces around the glass transition, which involves a response in the brittle/solid regime of these rock melts. We warn of the inadequacy of simple Newtonian viscous analyses and call for the application of more realistic rheological interpretation of pseudotachylyte-bearing fault systems in the evaluation and prediction of their slip dynamics. PMID:26124123

  20. Fault rheology beyond frictional melting.

    PubMed

    Lavallée, Yan; Hirose, Takehiro; Kendrick, Jackie E; Hess, Kai-Uwe; Dingwell, Donald B

    2015-07-28

    During earthquakes, comminution and frictional heating both contribute to the dissipation of stored energy. With sufficient dissipative heating, melting processes can ensue, yielding the production of frictional melts or "pseudotachylytes." It is commonly assumed that the Newtonian viscosities of such melts control subsequent fault slip resistance. Rock melts, however, are viscoelastic bodies, and, at high strain rates, they exhibit evidence of a glass transition. Here, we present the results of high-velocity friction experiments on a well-characterized melt that demonstrate how slip in melt-bearing faults can be governed by brittle fragmentation phenomena encountered at the glass transition. Slip analysis using models that incorporate viscoelastic responses indicates that even in the presence of melt, slip persists in the solid state until sufficient heat is generated to reduce the viscosity and allow remobilization in the liquid state. Where a rock is present next to the melt, we note that wear of the crystalline wall rock by liquid fragmentation and agglutination also contributes to the brittle component of these experimentally generated pseudotachylytes. We conclude that in the case of pseudotachylyte generation during an earthquake, slip even beyond the onset of frictional melting is not controlled merely by viscosity but rather by an interplay of viscoelastic forces around the glass transition, which involves a response in the brittle/solid regime of these rock melts. We warn of the inadequacy of simple Newtonian viscous analyses and call for the application of more realistic rheological interpretation of pseudotachylyte-bearing fault systems in the evaluation and prediction of their slip dynamics. PMID:26124123

  1. Detrital zircon provenance evidence for large-scale extrusion along the Altyn Tagh fault

    USGS Publications Warehouse

    Yue, Y.; Graham, S.A.; Ritts, B.D.; Wooden, J.L.

    2005-01-01

    The question of whether or not the Altyn Tagh fault is a large-scale extrusion boundary is critical for understanding the role of lateral extrusion in accommodating the Indo-Asian convergence and in building the Tibetan Plateau. Oligocene conglomerate clasts in the eastern Xorkol basin are low-grade slate, phyllite, sandstone, dacite and carbonate, and associated paleocurrent indicators evince sediment derivation from the opposing side of the Altyn Tagh fault. Matching these clasts with similar basement rocks in the North Qilian and Tuolainanshan terranes requires post-Oligocene left-lateral offset of 380 ?? 60 km on the eastern segment of the Altyn Tagh fault, suggesting large-scale extrusion along the fault in the Cenozoic (Yue, Y.J., Ritts, B.D., Graham, S.A., 2001b. Initiation and long-term slip history of the Altyn Tagh fault. International Geological Review 43, 1087-1094.). In order to further define this piercing point, the detrital zircon pattern of Oligocene sandstone from the Xorkol basin and the zircon ages of basement on the southern side of the fault were established by ion microprobe dating. Characterized by strong peaks between 850 and 950 Ma and the absence of Paleozoic and Mesozoic ages, the detrital zircon age pattern of the Oligocene sandstone matches the age distribution of zircon-bearing rocks of the Tuolainanshan terrane. This match requires 360 ?? 40 km of post-Oligocene left-lateral displacement on the eastern segment of the Altyn Tagh fault, supporting as well as refining the previously reported lithology-based cross-fault match. At least one of the following three extrusion scenarios must have existed to accommodate this large offset: (1) northeastward extrusion along the Altyn Tagh-Alxa-East Mongolia fault, (2) eastward extrusion along the Altyn Tagh-North Qilian-Haiyuan fault, and (3) northeastward extrusion of northern Tibet as a Himalaya-scale thrust sheet along the North Qilian-Haiyuan fault. We prefer the first scenario inasmuch as rapidly growing evidence for Cenozoic strike-slip activity on the Alxa-East Mongolia fault and mid-Miocene exhumation of northern Tibet supports it. ?? 2005 Elsevier B.V. All rights reserved.

  2. Architectures for fault-tolerant spacecraft computers

    NASA Technical Reports Server (NTRS)

    Rennels, D. A.

    1978-01-01

    This paper summarizes the results of a long-term research program in fault-tolerant computing for spacecraft on-board processing. In response to changing device technology this program has progressed from the design of a fault-tolerant uniprocessor to the development of fault-tolerant distributed computer systems. The unusual requirements of spacecraft computing are described along with the resulting real-time computer architectures. The following aspects of these designs are discussed: (1) architectural features to minimize complexity in the distributed computer system, (2) fault-detection and recovery, (3) techniques to enhance reliability and testability, and (4) design approaches for LSI implementation.

  3. Mantle fault zone beneath Kilauea Volcano, Hawaii

    USGS Publications Warehouse

    Wolfe, C.J.; Okubo, P.G.; Shearer, P.M.

    2003-01-01

    Relocations and focal mechanism analyses of deep earthquakes (???13 kilometers) at Kilauea volcano demonstrate that seismicity is focused on an active fault zone at 30-kilometer depth, with seaward slip on a low-angle plane, and other smaller, distinct fault zones. The earthquakes we have analyzed predominantly reflect tectonic faulting in the brittle lithosphere rather than magma movement associated with volcanic activity. The tectonic earthquakes may be induced on preexisting faults by stresses of magmatic origin, although background stresses from volcano loading and lithospheric flexure may also contribute.

  4. The mechanics of clay smearing along faults

    NASA Astrophysics Data System (ADS)

    Egholm, D. L.; Clausen, O. R.; Sandiford, M.; Kristensen, M. B.; Korstgård, J. A.

    2008-10-01

    A clay- or shale-rich fault gouge can significantly reduce faultpermeability. Therefore, predictions of the volume of clay orshale that may be smeared along a fault trace are importantfor estimating the fluid connectivity of groundwater and hydrocarbonreservoir systems. Here, we show how fault smears develop spontaneouslyin layered soil systems with varying friction coefficients,and we present a quantitative dynamic model for such behavior.The model is based on Mohr-Coulomb failure theory, and usingdiscrete element computations, we demonstrate how the modelframework can predict the fault smear potential from soil frictionangles and layer thicknesses.

  5. Mantle fault zone beneath Kilauea Volcano, Hawaii.

    PubMed

    Wolfe, Cecily J; Okubo, Paul G; Shearer, Peter M

    2003-04-18

    Relocations and focal mechanism analyses of deep earthquakes (>/=13 kilometers) at Kilauea volcano demonstrate that seismicity is focused on an active fault zone at 30-kilometer depth, with seaward slip on a low-angle plane, and other smaller, distinct fault zones. The earthquakes we have analyzed predominantly reflect tectonic faulting in the brittle lithosphere rather than magma movement associated with volcanic activity. The tectonic earthquakes may be induced on preexisting faults by stresses of magmatic origin, although background stresses from volcano loading and lithospheric flexure may also contribute. PMID:12702874

  6. Sequential Test Strategies for Multiple Fault Isolation

    NASA Technical Reports Server (NTRS)

    Shakeri, M.; Pattipati, Krishna R.; Raghavan, V.; Patterson-Hine, Ann; Kell, T.

    1997-01-01

    In this paper, we consider the problem of constructing near optimal test sequencing algorithms for diagnosing multiple faults in redundant (fault-tolerant) systems. The computational complexity of solving the optimal multiple-fault isolation problem is super-exponential, that is, it is much more difficult than the single-fault isolation problem, which, by itself, is NP-hard. By employing concepts from information theory and Lagrangian relaxation, we present several static and dynamic (on-line or interactive) test sequencing algorithms for the multiple fault isolation problem that provide a trade-off between the degree of suboptimality and computational complexity. Furthermore, we present novel diagnostic strategies that generate a static diagnostic directed graph (digraph), instead of a static diagnostic tree, for multiple fault diagnosis. Using this approach, the storage complexity of the overall diagnostic strategy reduces substantially. Computational results based on real-world systems indicate that the size of a static multiple fault strategy is strictly related to the structure of the system, and that the use of an on-line multiple fault strategy can diagnose faults in systems with as many as 10,000 failure sources.

  7. Applications of Fault Detection in Vibrating Structures

    NASA Technical Reports Server (NTRS)

    Eure, Kenneth W.; Hogge, Edward; Quach, Cuong C.; Vazquez, Sixto L.; Russell, Andrew; Hill, Boyd L.

    2012-01-01

    Structural fault detection and identification remains an area of active research. Solutions to fault detection and identification may be based on subtle changes in the time series history of vibration signals originating from various sensor locations throughout the structure. The purpose of this paper is to document the application of vibration based fault detection methods applied to several structures. Overall, this paper demonstrates the utility of vibration based methods for fault detection in a controlled laboratory setting and limitations of applying the same methods to a similar structure during flight on an experimental subscale aircraft.

  8. Transtensional structures along a transform fault

    SciTech Connect

    Jarvis, P.A.; Kroenke, L. ); Hughes-Clark, J. ); Tiffin, D. )

    1990-05-01

    Recently acquired side-scan imagery and single-channel seismic profiles along the Fiji transform fault reveal the structures produced by its sinistral motion. The fault extends from Peggy Ridge in the northern Lau basin into the central North Fiji basin, at least as far as the Viwa spreading ridge near Viti Levu, Fiji. A change in character of the fault along its length is evident in the imagery. Adjacent to the Fiji platform, the fault is clearly defined. Deformation and seismicity are confined to a narrow linear band which is offset by two left-stepping relay zones. Farther to the west in the north Fiji basin, however, the fault is not well defined. A series of ridges and basins occurs in a complicated region between 174{degree}E and 177{degree}E. These are produced by interaction of the fault with the nearby spreading centers. Interpretations differ as to the fault and spreading center geometry in this area. The arrangement of the tectonic element has controlled the formation of the observed structures. The intersection of the fault with the Viwa spreading ridge has features typical of ridge-transform insections. Within the complicated area between 174{degree} and 177{degree}E, the ridges and basins are postulated to be a consequence of the fault's shearing motion.

  9. Faults Discovery By Using Mined Data

    NASA Technical Reports Server (NTRS)

    Lee, Charles

    2005-01-01

    Fault discovery in the complex systems consist of model based reasoning, fault tree analysis, rule based inference methods, and other approaches. Model based reasoning builds models for the systems either by mathematic formulations or by experiment model. Fault Tree Analysis shows the possible causes of a system malfunction by enumerating the suspect components and their respective failure modes that may have induced the problem. The rule based inference build the model based on the expert knowledge. Those models and methods have one thing in common; they have presumed some prior-conditions. Complex systems often use fault trees to analyze the faults. Fault diagnosis, when error occurs, is performed by engineers and analysts performing extensive examination of all data gathered during the mission. International Space Station (ISS) control center operates on the data feedback from the system and decisions are made based on threshold values by using fault trees. Since those decision-making tasks are safety critical and must be done promptly, the engineers who manually analyze the data are facing time challenge. To automate this process, this paper present an approach that uses decision trees to discover fault from data in real-time and capture the contents of fault trees as the initial state of the trees.

  10. Block rotations, fault domains and crustal deformation

    NASA Technical Reports Server (NTRS)

    Nur, A.; Ron, H.

    1987-01-01

    Much of the earth's crust is broken by sets of parallel strike-slip faults which are organized in domains. A simple kinematic model suggests that when subject to tectonic strain, the faults, and the blocks bound by them, rotate. The rotation can be estimated from the structurally-determined fault slip and fault spacing, and independently from local deviations of paleomagnetic declinations from global values. A rigorous test of this model was carried out in northern Israel, where good agreement was found between the two rotations.

  11. Chip level simulation of fault tolerant computers

    NASA Technical Reports Server (NTRS)

    Armstrong, J. R.

    1983-01-01

    Chip level modeling techniques, functional fault simulation, simulation software development, a more efficient, high level version of GSP, and a parallel architecture for functional simulation are discussed.

  12. Evidence for Late Oligocene-Early Miocene episode of transtension along San Andreas Fault system in central California

    SciTech Connect

    Stanley, R.G.

    1986-04-01

    The San Andreas is one of the most intensely studied fault systems in the world, but many aspects of its kinematic history remain controversial. For example, the period from the late Eocene to early Miocene is widely believed to have been a time of negligible strike-slip movement along the San Andreas fault proper, based on the rough similarity of offset of the Eocene Butano-Point of rocks Submarine Fan, the early Miocene Pinnacles-Neenach volcanic center, and an early Miocene shoreline in the northern Gabilan Range and San Emigdio Mountains. Nonetheless, evidence indicates that a late Oligocene-early Miocene episode of transtension, or strike-slip motion with a component of extension, occurred within the San Andreas fault system. The evidence includes: (1) about 22-24 Ma, widespread, synchronous volcanic activity occurred at about 12 volcanic centers along a 400-km long segment of the central California coast; (2) most of these volcanic centers are located along faults of the San Andreas system, including the San Andreas fault proper, the San Gregorio-Hosgri fault, and the Zayante-Vergeles fault, suggesting that these and other faults were active and served as conduits for magmas rising from below; (3) during the late Oligocene and early Miocene, a pull-apart basin developed adjacent to the San Andreas fault proper in the La Honda basin near Santa Cruz; and (4) during the late Oligocene and early Miocene, active faulting, rapid subsidence, and marine transgression occurred in the La Honda and other sedimentary basins in central California. The amount of right-lateral displacement along the San Andreas fault proper during this transtentional episode is unknown but was probably about 7.5-35 km, based on model studies of pull-apart basin formation. This small amount of movement is well within the range of error in published estimates of the offset of the Eocene to early Miocene geologic features noted.

  13. Geometric analysis of faulted rollovers: Contrasting styles of extensional growth folding in the Gulf of Mexico and Offshore Trinidad

    SciTech Connect

    Bentham, P.A.

    1996-12-31

    Rapid sedimentation rates combined with the presences of seaward-dipping detachment levels in both the U.S. Gulf of Mexico (GOM) and the Columbus Basin (Offshore Trinidad) have facilitated the development of large extensional growth faults and their associated hanging-wall rollover folds. While detachment in the GOM is often associated with salt and/or overpresurred shale, shale is believed to be responsible for detachment and translation of large structural blocks within the Columbus Basin. Although, gravity-driven extension seems to be the primary mechanism driving structural development in both regions, the detailed structural geometries and deformational mechanisms present seem to be quite different. In the Columbus Basin, extensional rollovers are generally dominated by the presence of pervasive synthetic faults. Restoration of these structures suggests that these synthetic faults are accomodating the bulk hanging-wall deformation as the hanging-wall slides basinwards above an underlying listric fault surface. This synthetic simple shear deformation is not typically observed in Gulf of Mexico rollovers. In contrast, although synthetic faults are present, often observed in Gulf of Mexico rollovers. In contrast, although synthetic faults are present, often spatially associated with the master growth fault, antithetic or mixed antithetic/synthetic faulting dominates the crest of the structures. An antithetic simple shear deformation is borne out by simple geometric modeling and restoration. The synthetic faulting seem in Trinidadian rollovers to be influenced by the presence of important vertical pressure seals (major unconformities) that may act as internal detachment levels within the larger folds. Synthetic faults are often observed to sole or die downwards into these intervals. Generally, lateral closure of rollover anticlines in the GOM is controlled by the underlying scoop-like shape of the major listric growth faults.

  14. Geometric analysis of faulted rollovers: Contrasting styles of extensional growth folding in the Gulf of Mexico and Offshore Trinidad

    SciTech Connect

    Bentham, P.A. )

    1996-01-01

    Rapid sedimentation rates combined with the presences of seaward-dipping detachment levels in both the U.S. Gulf of Mexico (GOM) and the Columbus Basin (Offshore Trinidad) have facilitated the development of large extensional growth faults and their associated hanging-wall rollover folds. While detachment in the GOM is often associated with salt and/or overpresurred shale, shale is believed to be responsible for detachment and translation of large structural blocks within the Columbus Basin. Although, gravity-driven extension seems to be the primary mechanism driving structural development in both regions, the detailed structural geometries and deformational mechanisms present seem to be quite different. In the Columbus Basin, extensional rollovers are generally dominated by the presence of pervasive synthetic faults. Restoration of these structures suggests that these synthetic faults are accomodating the bulk hanging-wall deformation as the hanging-wall slides basinwards above an underlying listric fault surface. This synthetic simple shear deformation is not typically observed in Gulf of Mexico rollovers. In contrast, although synthetic faults are present, often observed in Gulf of Mexico rollovers. In contrast, although synthetic faults are present, often spatially associated with the master growth fault, antithetic or mixed antithetic/synthetic faulting dominates the crest of the structures. An antithetic simple shear deformation is borne out by simple geometric modeling and restoration. The synthetic faulting seem in Trinidadian rollovers to be influenced by the presence of important vertical pressure seals (major unconformities) that may act as internal detachment levels within the larger folds. Synthetic faults are often observed to sole or die downwards into these intervals. Generally, lateral closure of rollover anticlines in the GOM is controlled by the underlying scoop-like shape of the major listric growth faults.

  15. Fault-tolerant parallel processor

    SciTech Connect

    Harper, R.E.; Lala, J.H. )

    1991-06-01

    This paper addresses issues central to the design and operation of an ultrareliable, Byzantine resilient parallel computer. Interprocessor connectivity requirements are met by treating connectivity as a resource that is shared among many processing elements, allowing flexibility in their configuration and reducing complexity. Redundant groups are synchronized solely by message transmissions and receptions, which aslo provide input data consistency and output voting. Reliability analysis results are presented that demonstrate the reduced failure probability of such a system. Performance analysis results are presented that quantify the temporal overhead involved in executing such fault-tolerance-specific operations. Empirical performance measurements of prototypes of the architecture are presented. 30 refs.

  16. SUMC fault tolerant computer system

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The results of the trade studies are presented. These trades cover: establishing the basic configuration, establishing the CPU/memory configuration, establishing an approach to crosstrapping interfaces, defining the requirements of the redundancy management unit (RMU), establishing a spare plane switching strategy for the fault-tolerant memory (FTM), and identifying the most cost effective way of extending the memory addressing capability beyond the 64 K-bytes (K=1024) of SUMC-II B. The results of the design are compiled in Contract End Item (CEI) Specification for the NASA Standard Spacecraft Computer II (NSSC-II), IBM 7934507. The implementation of the FTM and memory address expansion.

  17. Robust fault detection filter design

    NASA Astrophysics Data System (ADS)

    Douglas, Randal Kirk

    The detection filter is a specially tuned linear observer that forms the residual generation part of an analytical redundancy system designed for model-based fault detection and identification. The detection filter has an invariant state subspace structure that produces a residual with known and fixed directional characteristics in response to a known design fault direction. In addition to a parameterization of the detection filter gain, three methods are given for improving performance in the presence of system disturbances, sensor noise, model mismatch and sensitivity to small parameter variations. First, it is shown that by solving a modified algebraic Riccati equation, a stabilizing detection filter gain is found that bounds the H-infinity norm of the transfer matrix from system disturbances and sensor noise to the detection filter residual. Second, a specially chosen expanded-order detection filter is formed with fault detection properties identical to a set of independent reduced-order filters that have no structural constraints. This result is important to the practitioner because the difficult problem of finding a detection filter insensitive to disturbances and sensor noise is converted to the easier problem of finding a set of uncoupled noise insensitive filters. Furthermore, the statistical properties of the reduced-order filter residuals are easier to find than the statistical properties of the structurally constrained detection filter residual. Third, an interpretation of the detection filter as a special case of the dual of the restricted decoupling problem leads to a new detection filter eigenstructure assignment algorithm. The new algorithm places detection filter left eigenvectors, which annihilate the detection spaces, rather than right eigenvectors, which span the detection spaces. This allows for a more flexible observer based fault detection system structure that could not be formulated as a detection filter. Furthermore, the link to the dual problem allows existing results relating supremal controllability subspaces and ill-conditioned eigenvector to be easily applied to the detection filter. The practitioner will find these results useful as they provide guidelines for desensitizing the detection filter to small parameter variations.

  18. The morphology of strike-slip faults - Examples from the San Andreas Fault, California

    NASA Technical Reports Server (NTRS)

    Bilham, Roger; King, Geoffrey

    1989-01-01

    The dilatational strains associated with vertical faults embedded in a horizontal plate are examined in the framework of fault kinematics and simple displacement boundary conditions. Using boundary element methods, a sequence of examples of dilatational strain fields associated with commonly occurring strike-slip fault zone features (bends, offsets, finite rupture lengths, and nonuniform slip distributions) is derived. The combinations of these strain fields are then used to examine the Parkfield region of the San Andreas fault system in central California.

  19. Processes of sedimentation associated with fault-controlled trough across a shelf

    SciTech Connect

    Rees, M.N.

    1985-02-01

    Western North America was a rapidly subsiding, passive continental margin during the Cambrian. During the Middle Cambrian, a belt of carbonate deposition dominated the central shelf. It was bounded by fine-grained terrigenous sediments that accumulated in deep water to the west and in shallow water to the east. Movement along a high-angle fault that extended across the shelf produced a conspicuous embayment into the carbonate belt in Nevada and Utah during the middle Middle Cambrian. This fault movement controlled basin geometry and distribution of carbonate and shale lithofacies on the shelf for at least the next 40 m.y. The embayment was an asymmetrical trough that deepened and widened as it extended some 400 km westward toward the edge of the continent. South of its abrupt southern margin, which marked the position of the fault, shallow subtidal and peritidal sediments accumulated throughout the Middle Cambrian. The northern flank of the embayment was a drowned platform that sloped gently southward into the trough axis. On this ramp, a carbonate platform was rapidly reestablished through vertical accretion and progradation. In the trough axis, which lay near the faulted margin, sediments representing anoxic and deep-water environments accumulated throughout the middle and late Middle Cambrian. Sedimentation rates in this axial region were inadequate to reestablish a shallow-water depositional setting because of reactivation of faulting and because the trough acted as a sediment bypass zone.

  20. Estimating the distribution of fault latency in a digital processor

    NASA Technical Reports Server (NTRS)

    Ellis, Erik L.; Butler, Ricky W.

    1987-01-01

    Presented is a statistical approach to measuring fault latency in a digital processor. The method relies on the use of physical fault injection where the duration of the fault injection can be controlled. Although a specific fault's latency period is never directly measured, the method indirectly determines the distribution of fault latency.

  1. Continuous creep measurements on the North Anatolian fault

    NASA Astrophysics Data System (ADS)

    Bilham, Roger; Mencin, David; Mattioli, Glen; Ozner, Haluk; Dogru, Asli; Ergintav, Semih; Cakir, Ziyadin; Aytun, Alkut; Hodgkinson, Kathleen; Johnson, Wade; Gottlieb, Mike; VanBoskirk, Liz

    2015-04-01

    Surface creep was observed as early as 1969 on the North Anatolian fault near Ismetpasa and continues to the present day at rates of the order of 5 mm/yr. Although subsurface creep is currently monitored using INSAR and GPS, continuous creep measurements on the trace of the surface fault have been intermittent. In 2014, we installed a carbon-fiber rod creepmeter at Ismetpasa and a second creepmeter across the surface rupture of the 1999 Izmit earthquake, which is also known to be creeping at depth. The creepmeters have a resolution of 5 µm and a dynamic range of 2.2 m. Each creepmeter uses two sensors: 1) a subsurface LVDT (resolution 5 µm, range 10 mm) and an above-ground rotary Hall effect sensor (resolution 25 µm, range 2.2 m) and the data are transmitted via Iridium satellite communications as 30 minute samples every 2 hours. The hybrid sensors on the creepmeters are similar to others currently operating on the Hayward, Calaveras, and San Andreas faults. The sensor's ability to capture slow slip, coseismic rupture or afterslip has been tested in deployments on the rapidly creeping Jackson, Wyoming landslide (1-3 mm/day). In addition, we have installed six borehole strainmeters to measure creep on the Princess Island segment of the North Anatolian fault to the west of Ismetpasa. The tensor strainmeters are able to measure strain events on 10e-10 strain and they can resolve 1 mm creep events on the order of 500 m2 at distances of 4 km away based on observations from deployed instruments along the San Andreas Fault in Southern California. The tensor strainmeters are unique geodetic instruments in that they are capable of imaging the creep in high resolution where the North Anatolian fault (NAF) is submarine in the Sea of Marmara. The newly installed creepmeters and strainmeters will be powerful tools to examine the possibilities of the transient or episodic creep along the NAF and they will be used to validate the results of on-going monthly INSAR, continuous, and campaign GPS studies, along the NAF.

  2. Application of padmounted fault interrupters to single-phase URD systems

    SciTech Connect

    Israel, W.F.

    1995-12-31

    Underground distribution has proven itself to be a highly effective means of eliminating the temporary faults that plague overhead distribution, however, the permanent faults that do occur are often cable or splice failures which are unpredictable, difficult to locate and require a lot of time and expense to repair. One of the ways that the designer seeks to minimize the impact of such events on service reliability is by incorporating an overcurrent protection scheme which removes the faulted section from the rest of the system and contingency scheme which allows isolation of the faulted section and restoration of service in the shortest possible time with a minimal number of switching operations. As a result there has been a continuing interest in the development of devices, equipment, and methods which help to realize the ideals of rapid service restoration and isolation of faults to the smallest segment of the system. Overcurrent protection of the single-phase URD system has, traditionally, been the province of fused cutouts and fused padmounted sectionalizing terminals and switchgear. Recently however, padmounted vacuum fault interrupters, that utilize electronic controls for tripping, have become available from several manufacturers and are beginning to make inroads into this portion of the distribution system. This paper will discuss the characteristics and potential applications of a new product offered by Cooper Power Systems, the Shrubline VFI, which was designed specifically for use in single phase residential underground distribution.

  3. Active tectonics of the Beichuan and Pengguan faults at the eastern margin of the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Densmore, Alexander L.; Ellis, Michael A.; Li, Yong; Zhou, Rongjun; Hancock, Gregory S.; Richardson, Nicholas

    2007-08-01

    The steep, high-relief eastern margin of the Tibetan Plateau has undergone rapid Cenozoic cooling and denudation yet shows little evidence for large-magnitude shortening or accommodation generation in the foreland basin. We address this paradox by using a variety of geomorphic observations to place constraints on the kinematics and slip rates of several large faults that parallel the plateau margin. The Beichuan and Pengguan faults are active, dominantly dextral-slip structures that can be traced continuously for up to 200 km along the plateau margin. Both faults offset fluvial fill terraces that yield inheritance-corrected, cosmogenic 10Be exposure ages of <15 kyr, indicating latest Pleistocene activity. The Pengguan fault appears to have been active in the Holocene at two sites along strike. Latest Quaternary apparent throw rates on both faults are variable along strike but are typically <1 mm yr-1. Rates of strike-slip displacement are likely to be several times higher, probably ˜1-10 mm yr-1 but remain poorly constrained. Late Quaternary folding and dextral strike-slip has also occurred along the western margin of the Sichuan Basin, particularly associated with the present-day mountain front. These observations support models for the formation and maintenance of the eastern plateau margin that do not involve major upper crustal shortening. They also suggest that activity on the margin-parallel faults in eastern Tibet may represent a significant seismic hazard to the densely populated Sichuan Basin.

  4. Sensor and Sensorless Fault Tolerant Control for Induction Motors Using a Wavelet Index

    PubMed Central

    Gaeid, Khalaf Salloum; Ping, Hew Wooi; Khalid, Mustafa; Masaoud, Ammar

    2012-01-01

    Fault Tolerant Control (FTC) systems are crucial in industry to ensure safe and reliable operation, especially of motor drives. This paper proposes the use of multiple controllers for a FTC system of an induction motor drive, selected based on a switching mechanism. The system switches between sensor vector control, sensorless vector control, closed-loop voltage by frequency (V/f) control and open loop V/f control. Vector control offers high performance, while V/f is a simple, low cost strategy with high speed and satisfactory performance. The faults dealt with are speed sensor failures, stator winding open circuits, shorts and minimum voltage faults. In the event of compound faults, a protection unit halts motor operation. The faults are detected using a wavelet index. For the sensorless vector control, a novel Boosted Model Reference Adaptive System (BMRAS) to estimate the motor speed is presented, which reduces tuning time. Both simulation results and experimental results with an induction motor drive show the scheme to be a fast and effective one for fault detection, while the control methods transition smoothly and ensure the effectiveness of the FTC system. The system is also shown to be flexible, reverting rapidly back to the dominant controller if the motor returns to a healthy state. PMID:22666016

  5. Large-magnitude transient strain accumulation on the Blackwater fault, Eastern California shear zone

    NASA Astrophysics Data System (ADS)

    Oskin, Michael; Iriondo, Alex

    2004-04-01

    We investigate the Quaternary slip rate for the Blackwater fault, Eastern California shear zone, through mapping and geochronology of offset volcanic rocks. Basalt flows of the Black Mountains support the presence of faulting at 3.77 ± 0.11 Ma, 1.8 ± 0.1 km of subsequent slip, and a well-constrained long-term slip rate of 0.49 ± 0.04 mm/yr. Total slip diminishes northward, evidenced by a 0.3 1.8 km offset of a 7.23 ± 1.07 Ma dacite flow in the Black Hills and fault termination in the Lava Mountains, 5 km short of the Garlock fault. Slow long-term slip rate together with sparse evidence for Holocene rupture contradict predictions of rapid slip rate from tectonic geodesy. These results support the conclusion that as much as 95% of geodetic strain accumulation across the Blackwater fault, and thus from 1 to 6 mm/yr of geodetic strain measured across the Eastern California shear zone, is a transitory phenomenon. Discrepant geologic and geodetic results may indicate an increased near-term seismic hazard, but merit caution for interpretation of fault slip rates from geodesy alone.

  6. Sensor and sensorless fault tolerant control for induction motors using a wavelet index.

    PubMed

    Gaeid, Khalaf Salloum; Ping, Hew Wooi; Khalid, Mustafa; Masaoud, Ammar

    2012-01-01

    Fault Tolerant Control (FTC) systems are crucial in industry to ensure safe and reliable operation, especially of motor drives. This paper proposes the use of multiple controllers for a FTC system of an induction motor drive, selected based on a switching mechanism. The system switches between sensor vector control, sensorless vector control, closed-loop voltage by frequency (V/f) control and open loop V/f control. Vector control offers high performance, while V/f is a simple, low cost strategy with high speed and satisfactory performance. The faults dealt with are speed sensor failures, stator winding open circuits, shorts and minimum voltage faults. In the event of compound faults, a protection unit halts motor operation. The faults are detected using a wavelet index. For the sensorless vector control, a novel Boosted Model Reference Adaptive System (BMRAS) to estimate the motor speed is presented, which reduces tuning time. Both simulation results and experimental results with an induction motor drive show the scheme to be a fast and effective one for fault detection, while the control methods transition smoothly and ensure the effectiveness of the FTC system. The system is also shown to be flexible, reverting rapidly back to the dominant controller if the motor returns to a healthy state. PMID:22666016

  7. Polyscale, polymodal fault geometries: evolution and predictive capability

    NASA Astrophysics Data System (ADS)

    Blenkinsop, T. G.; Carvell, J.; Clarke, G.; Tonelli, M.

    2012-12-01

    The Late Permian Rangal coal measures on the edge of the Nebo synclinorium in the Bowen basin, NE Queensland, Australia, are cut by normal faults. Mining operations allow 13 faults to be mapped in some detail to depths of 200m. These faults cut Tertiary intrusions and a reverse fault as well as the coal seams, and show no obvious signs of reactivation. The steeply dipping faults are clustered into groups of two to four, separated by hundreds of meters. The faults trend ENE and NE; both trends of faults dip in both directions, defining a quadrimodal geometry. The odd axis construction for these faults suggests that vertical shortening was accompanied by horizontal extension along both principal directions of 153° and 063°. The mapped extents of the faults are limited by erosion and the depth to which the faults have been drilled, but displacement profiles along the lengths of the faults show maxima within the fault planes. The displacement profiles suggest that the currently mapped faults have similar lengths to the total preserved lengths of the faults, and that they will continue into the unmined ground to a limited, but predictable extent. The fault planes have a complex geometry, with segments of individual faults showing a similar variability in orientation to the ensemble of fault planes: the fault planes themselves are polymodal. Displacement profiles show a good correlation with segment orientation. An odd axis construction based on fault segments, rather than individual faults, gives principal extension directions within 4° of the above results. The variable orientation of fault segments, the correlation of the displacement profiles with fault orientation, and the similarity between the segment and ensemble fault kinematics suggest that the faults have evolved by propagation and linking of smaller polymodal faults in the same bulk strain field.ross section of polymodal fault at Hail Creek coal mine

  8. Review: Evaluation of Foot-and-Mouth Disease Control Using Fault Tree Analysis.

    PubMed

    Isoda, N; Kadohira, M; Sekiguchi, S; Schuppers, M; Stärk, K D C

    2015-06-01

    An outbreak of foot-and-mouth disease (FMD) causes huge economic losses and animal welfare problems. Although much can be learnt from past FMD outbreaks, several countries are not satisfied with their degree of contingency planning and aiming at more assurance that their control measures will be effective. The purpose of the present article was to develop a generic fault tree framework for the control of an FMD outbreak as a basis for systematic improvement and refinement of control activities and general preparedness. Fault trees are typically used in engineering to document pathways that can lead to an undesired event, that is, ineffective FMD control. The fault tree method allows risk managers to identify immature parts of the control system and to analyse the events or steps that will most probably delay rapid and effective disease control during a real outbreak. The present developed fault tree is generic and can be tailored to fit the specific needs of countries. For instance, the specific fault tree for the 2001 FMD outbreak in the UK was refined based on control weaknesses discussed in peer-reviewed articles. Furthermore, the specific fault tree based on the 2001 outbreak was applied to the subsequent FMD outbreak in 2007 to assess the refinement of control measures following the earlier, major outbreak. The FMD fault tree can assist risk managers to develop more refined and adequate control activities against FMD outbreaks and to find optimum strategies for rapid control. Further application using the current tree will be one of the basic measures for FMD control worldwide. PMID:23809890

  9. Dynamic modeling of the 1999 Izmit, Turkey earthquake on non-planar fault models

    NASA Astrophysics Data System (ADS)

    Aochi, H.; Madariaga, R.

    2002-12-01

    We simulated dynamic rupture propagation along various non-planar fault models proposed for the 1999 İzmit, earthquake in Turkey using a BIEM (boundary integral equation method). These models were inspired by those proposed by several authors from seismological, geological and geodetic observations. Once the dynamic rupture process was computed, we modeled seismic wave propagation from the fault to strong ground motion stations using a FDM (finite difference method). Our results indicate that near field strong motion is very much influenced by details of the rupture progress, which is in turn are very sensitive to small differences in fault geometry. Both observed and synthetic near-field seismograms, confirm a rapid and continuous rupture propagation from the İzmit-Sapanca lake segment to the Sapanca-Akyazi segment. Rupture under Sapanca lake appears to have propagated not across a discontinuous fault segment, but along a smooth fault structure with a bend of only a few degrees. In order to explain near-field seismogram at station SKR, located only a few km away from the fault, we had to force rupture to propagate at shallow depth near to the station. In order to obtain this we had to introduce a finite cohesive force in the friction law near the surface, so that stress accumulation and release can occur in the very shallow crust. The external stress field had to be large enough for rupture to propagate at very rapid speed. Our simulations show that details of the fault geometry have a substantial effect on rupture propagation and the generation of rupture pulses required to explain strong motion records at the available stations.

  10. Frictional heterogeneities on carbonate-bearing normal faults: Insights from the Monte Maggio Fault, Italy

    NASA Astrophysics Data System (ADS)

    Carpenter, B. M.; Scuderi, M. M.; Collettini, C.; Marone, C.

    2014-12-01

    Observations of heterogeneous and complex fault slip are often attributed to the complexity of fault structure and/or spatial heterogeneity of fault frictional behavior. Such complex slip patterns have been observed for earthquakes on normal faults throughout central Italy, where many of the Mw 6 to 7 earthquakes in the Apennines nucleate at depths where the lithology is dominated by carbonate rocks. To explore the relationship between fault structure and heterogeneous frictional properties, we studied the exhumed Monte Maggio Fault, located in the northern Apennines. We collected intact specimens of the fault zone, including the principal slip surface and hanging wall cataclasite, and performed experiments at a normal stress of 10 MPa under saturated conditions. Experiments designed to reactivate slip between the cemented principal slip surface and cataclasite show a 3 MPa stress drop as the fault surface fails, then velocity-neutral frictional behavior and significant frictional healing. Overall, our results suggest that (1) earthquakes may readily nucleate in areas of the fault where the slip surface separates massive limestone and are likely to propagate in areas where fault gouge is in contact with the slip surface; (2) postseismic slip is more likely to occur in areas of the fault where gouge is present; and (3) high rates of frictional healing and low creep relaxation observed between solid fault surfaces could lead to significant aftershocks in areas of low stress drop.

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

    NASA Technical Reports Server (NTRS)

    Bergman, Eric A.; Solomon, Sean C.

    1987-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Bergman, Eric A.; Solomon, Sean C.

    1988-01-01

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

  13. Rapid shallow breathing

    MedlinePlus

    Tachypnea; Breathing - rapid and shallow; Fast shallow breathing; Respiratory rate - rapid and shallow ... Shallow, rapid breathing has many possible medical causes, including: Asthma Blood clot in an artery in the lung Choking Chronic obstructive ...

  14. On Identifiability of Bias-Type Actuator-Sensor Faults in Multiple-Model-Based Fault Detection and Identification

    NASA Technical Reports Server (NTRS)

    Joshi, Suresh M.

    2012-01-01

    This paper explores a class of multiple-model-based fault detection and identification (FDI) methods for bias-type faults in actuators and sensors. These methods employ banks of Kalman-Bucy filters to detect the faults, determine the fault pattern, and estimate the fault values, wherein each Kalman-Bucy filter is tuned to a different failure pattern. Necessary and sufficient conditions are presented for identifiability of actuator faults, sensor faults, and simultaneous actuator and sensor faults. It is shown that FDI of simultaneous actuator and sensor faults is not possible using these methods when all sensors have biases.

  15. Implications of fault constitutive properties for earthquake prediction.

    PubMed

    Dieterich, J H; Kilgore, B

    1996-04-30

    The rate- and state-dependent constitutive formulation for fault slip characterizes an exceptional variety of materials over a wide range of sliding conditions. This formulation provides a unified representation of diverse sliding phenomena including slip weakening over a characteristic sliding distance Dc, apparent fracture energy at a rupture front, time-dependent healing after rapid slip, and various other transient and slip rate effects. Laboratory observations and theoretical models both indicate that earthquake nucleation is accompanied by long intervals of accelerating slip. Strains from the nucleation process on buried faults generally could not be detected if laboratory values of Dc apply to faults in nature. However, scaling of Dc is presently an open question and the possibility exists that measurable premonitory creep may precede some earthquakes. Earthquake activity is modeled as a sequence of earthquake nucleation events. In this model, earthquake clustering arises from sensitivity of nucleation times to the stress changes induced by prior earthquakes. The model gives the characteristic Omori aftershock decay law and assigns physical interpretation to aftershock parameters. The seismicity formulation predicts large changes of earthquake probabilities result from stress changes. Two mechanisms for foreshocks are proposed that describe observed frequency of occurrence of foreshock-mainshock pairs by time and magnitude. With the first mechanism, foreshocks represent a manifestation of earthquake clustering in which the stress change at the time of the foreshock increases the probability of earthquakes at all magnitudes including the eventual mainshock. With the second model, accelerating fault slip on the mainshock nucleation zone triggers foreshocks. PMID:11607666

  16. Implications of fault constitutive properties for earthquake prediction

    USGS Publications Warehouse

    Dieterich, J.H.; Kilgore, B.

    1996-01-01

    The rate- and state-dependent constitutive formulation for fault slip characterizes an exceptional variety of materials over a wide range of sliding conditions. This formulation provides a unified representation of diverse sliding phenomena including slip weakening over a characteristic sliding distance D(c), apparent fracture energy at a rupture front, time- dependent healing after rapid slip, and various other transient and slip rate effects. Laboratory observations and theoretical models both indicate that earthquake nucleation is accompanied by long intervals of accelerating slip. Strains from the nucleation process on buried faults generally could not be detected if laboratory values of D, apply to faults in nature. However, scaling of D(c) is presently an open question and the possibility exists that measurable premonitory creep may precede some earthquakes. Earthquake activity is modeled as a sequence of earthquake nucleation events. In this model, earthquake clustering arises from sensitivity of nucleation times to the stress changes induced by prior earthquakes. The model gives the characteristic Omori aftershock decay law and assigns physical interpretation to aftershock parameters. The seismicity formulation predicts large changes of earthquake probabilities result from stress changes. Two mechanisms for foreshocks are proposed that describe observed frequency of occurrence of foreshock-mainshock pairs by time and magnitude. With the first mechanism, foreshocks represent a manifestation of earthquake clustering in which the stress change at the time of the foreshock increases the probability of earthquakes at all magnitudes including the eventual mainshock. With the second model, accelerating fault slip on the mainshock nucleation zone triggers foreshocks.

  17. Implications of fault constitutive properties for earthquake prediction.

    PubMed Central

    Dieterich, J H; Kilgore, B

    1996-01-01

    The rate- and state-dependent constitutive formulation for fault slip characterizes an exceptional variety of materials over a wide range of sliding conditions. This formulation provides a unified representation of diverse sliding phenomena including slip weakening over a characteristic sliding distance Dc, apparent fracture energy at a rupture front, time-dependent healing after rapid slip, and various other transient and slip rate effects. Laboratory observations and theoretical models both indicate that earthquake nucleation is accompanied by long intervals of accelerating slip. Strains from the nucleation process on buried faults generally could not be detected if laboratory values of Dc apply to faults in nature. However, scaling of Dc is presently an open question and the possibility exists that measurable premonitory creep may precede some earthquakes. Earthquake activity is modeled as a sequence of earthquake nucleation events. In this model, earthquake clustering arises from sensitivity of nucleation times to the stress changes induced by prior earthquakes. The model gives the characteristic Omori aftershock decay law and assigns physical interpretation to aftershock parameters. The seismicity formulation predicts large changes of earthquake probabilities result from stress changes. Two mechanisms for foreshocks are proposed that describe observed frequency of occurrence of foreshock-mainshock pairs by time and magnitude. With the first mechanism, foreshocks represent a manifestation of earthquake clustering in which the stress change at the time of the foreshock increases the probability of earthquakes at all magnitudes including the eventual mainshock. With the second model, accelerating fault slip on the mainshock nucleation zone triggers foreshocks. Images Fig. 3 PMID:11607666

  18. Constitutive relations for fault slip and earthquake instabilities

    NASA Astrophysics Data System (ADS)

    Rice, James R.

    1983-05-01

    Constitutive relations for fault slip are described and adopted as a basis for analyzing slip motion and its instability in the form of earthquakes on crustal faults. The constitutive relations discussed include simple rate-independent slip-weakening models, in which shear strength degrades with ongoing slip to a residual frictional strength, and also more realistic but as yet less extensively applied slip-rate and surface-state-dependent relations. For the latter the state of the surface is characterized by one or more variables that evolve with ongoing slip, seeking values consistent with the current slip rate. Models of crustal faults range from simple, single-degree-of-freedom spring-slider systems to more complex continuous systems that incorporate nonuniform slip and locked patches on faults of depth-dependent constitutive properties within elastic lithospheric plates that may be coupled to a viscoelastic asthenosphere. Most progress for the rate and state-dependent constitutive relations is at present limited to single-degree-of-freedom systems. Results for stable and unstable slip with the various constitutive models are summarized. Instability conditions are compared for spatially uniform versus nonuniform slip, including the elastic — brittle crack limit of the nonuniform mode. Inferences of constitutive and fracture parameters are discussed, based on earthquake data for large ruptures that begin with slip at depth, concentrating stress on locked regions within a brittle upper crust. Results of nonlinear stability theory, including regimes of complex sustained stress and slip rate oscillations, are outlined for rate and state-dependent constitutive relations, and the manner in which these allow phenomena like time-dependent failure, restrengthening in nearly stationary contact, and weakening in rapidly accelerated slip, is discussed.

  19. Seismic images and fault relations of the Santa Monica thrust fault, West Los Angeles, California

    USGS Publications Warehouse

    Catchings, R.D.; Gandhok, G.; Goldman, M.R.; Okaya, D.

    2001-01-01

    In May 1997, the US Geological Survey (USGS) and the University of Southern California (USC) acquired high-resolution seismic reflection and refraction images on the grounds of the Wadsworth Veterans Administration Hospital (WVAH) in the city of Los Angeles (Fig. 1a,b). The objective of the seismic survey was to better understand the near-surface geometry and faulting characteristics of the Santa Monica fault zone. In this report, we present seismic images, an interpretation of those images, and a comparison of our results with results from studies by Dolan and Pratt (1997), Pratt et al. (1998) and Gibbs et al. (2000). The Santa Monica fault is one of the several northeast-southwest-trending, north-dipping, reverse faults that extend through the Los Angeles metropolitan area (Fig. 1a). Through much of area, the Santa Monica fault trends subparallel to the Hollywood fault, but the two faults apparently join into a single fault zone to the southwest and to the northeast (Dolan et al., 1995). The Santa Monica and Hollywood faults may be part of a larger fault system that extends from the Pacific Ocean to the Transverse Ranges. Crook et al. (1983) refer to this fault system as the Malibu Coast-Santa Monica-Raymond-Cucamonga fault system. They suggest that these faults have not formed a contiguous zone since the Pleistocene and conclude that each of the faults should be treated as a separate fault with respect to seismic hazards. However, Dolan et al. (1995) suggest that the Hollywood and Santa Monica faults are capable of generating Mw 6.8 and Mw 7.0 earthquakes, respectively. Thus, regardless of whether the overall fault system is connected and capable of rupturing in one event, individually, each of the faults present a sizable earthquake hazard to the Los Angeles metropolitan area. If, however, these faults are connected, and they were to rupture along a continuous fault rupture, the resulting hazard would be even greater. Although the Santa Monica fault represents a hazard to millions of people, its lateral extent and rupture history are not well known, due largely to limited knowledge of the fault location, geometry, and relationship to other faults. The Santa Monica fault has been obscured at the surface by alluvium and urbanization. For example, Dolan et al. (1995) could find only one 200-m-long stretch of the Santa Monica fault that was not covered by either streets or buildings. Of the 19-km length onshore section of the Santa Monica fault, its apparent location has been delineated largely on the basis of geomorphic features and oil-well drilling. Seismic imaging efforts, in combination with other investigative methods, may be the best approach in locating and understanding the Santa Monica fault in the Los Angeles region. This investigation and another recent seismic imaging investigation (Pratt et al., 1998) were undertaken to resolve the near-surface location, fault geometry, and faulting relations associated with the Santa Monica fault.

  20. Illuminating Northern California's Active Faults

    NASA Astrophysics Data System (ADS)

    Prentice, Carol S.; Crosby, Christopher J.; Whitehill, Caroline S.; Arrowsmith, J. Ramón; Furlong, Kevin P.; Phillips, David A.

    2009-02-01

    Newly acquired light detection and ranging (lidar) topographic data provide a powerful community resource for the study of landforms associated with the plate boundary faults of northern California (Figure 1). In the spring of 2007, GeoEarthScope, a component of the EarthScope Facility construction project funded by the U.S. National Science Foundation, acquired approximately 2000 square kilometers of airborne lidar topographic data along major active fault zones of northern California. These data are now freely available in point cloud (x, y, z coordinate data for every laser return), digital elevation model (DEM), and KMZ (zipped Keyhole Markup Language, for use in Google Earth™ and other similar software) formats through the GEON OpenTopography Portal (http://www.OpenTopography.org/data). Importantly, vegetation can be digitally removed from lidar data, producing high-resolution images (0.5- or 1.0-meter DEMs) of the ground surface beneath forested regions that reveal landforms typically obscured by vegetation canopy (Figure 2).

  1. Fault Tolerant Homopolar Magnetic Bearings

    NASA Technical Reports Server (NTRS)

    Li, Ming-Hsiu; Palazzolo, Alan; Kenny, Andrew; Provenza, Andrew; Beach, Raymond; Kascak, Albert

    2003-01-01

    Magnetic suspensions (MS) satisfy the long life and low loss conditions demanded by satellite and ISS based flywheels used for Energy Storage and Attitude Control (ACESE) service. This paper summarizes the development of a novel MS that improves reliability via fault tolerant operation. Specifically, flux coupling between poles of a homopolar magnetic bearing is shown to deliver desired forces even after termination of coil currents to a subset of failed poles . Linear, coordinate decoupled force-voltage relations are also maintained before and after failure by bias linearization. Current distribution matrices (CDM) which adjust the currents and fluxes following a pole set failure are determined for many faulted pole combinations. The CDM s and the system responses are obtained utilizing 1D magnetic circuit models with fringe and leakage factors derived from detailed, 3D, finite element field models. Reliability results are presented vs. detection/correction delay time and individual power amplifier reliability for 4, 6, and 7 pole configurations. Reliability is shown for two success criteria, i.e. (a) no catcher bearing contact following pole failures and (b) re-levitation off of the catcher bearings following pole failures. An advantage of the method presented over other redundant operation approaches is a significantly reduced requirement for backup hardware such as additional actuators or power amplifiers.

  2. Fault Management Techniques in Human Spaceflight Operations

    NASA Technical Reports Server (NTRS)

    O'Hagan, Brian; Crocker, Alan

    2006-01-01

    This paper discusses human spaceflight fault management operations. Fault detection and response capabilities available in current US human spaceflight programs Space Shuttle and International Space Station are described while emphasizing system design impacts on operational techniques and constraints. Preflight and inflight processes along with products used to anticipate, mitigate and respond to failures are introduced. Examples of operational products used to support failure responses are presented. Possible improvements in the state of the art, as well as prioritization and success criteria for their implementation are proposed. This paper describes how the architecture of a command and control system impacts operations in areas such as the required fault response times, automated vs. manual fault responses, use of workarounds, etc. The architecture includes the use of redundancy at the system and software function level, software capabilities, use of intelligent or autonomous systems, number and severity of software defects, etc. This in turn drives which Caution and Warning (C&W) events should be annunciated, C&W event classification, operator display designs, crew training, flight control team training, and procedure development. Other factors impacting operations are the complexity of a system, skills needed to understand and operate a system, and the use of commonality vs. optimized solutions for software and responses. Fault detection, annunciation, safing responses, and recovery capabilities are explored using real examples to uncover underlying philosophies and constraints. These factors directly impact operations in that the crew and flight control team need to understand what happened, why it happened, what the system is doing, and what, if any, corrective actions they need to perform. If a fault results in multiple C&W events, or if several faults occur simultaneously, the root cause(s) of the fault(s), as well as their vehicle-wide impacts, must be determined in order to maintain situational awareness. This allows both automated and manual recovery operations to focus on the real cause of the fault(s). An appropriate balance must be struck between correcting the root cause failure and addressing the impacts of that fault on other vehicle components. Lastly, this paper presents a strategy for using lessons learned to improve the software, displays, and procedures in addition to determining what is a candidate for automation. Enabling technologies and techniques are identified to promote system evolution from one that requires manual fault responses to one that uses automation and autonomy where they are most effective. These considerations include the value in correcting software defects in a timely manner, automation of repetitive tasks, making time critical responses autonomous, etc. The paper recommends the appropriate use of intelligent systems to determine the root causes of faults and correctly identify separate unrelated faults.

  3. Fault slip during a glacial cycle

    NASA Astrophysics Data System (ADS)

    Steffen, Rebekka; Wu, Patrick; Steffen, Holger; Eaton, Dave

    2013-04-01

    Areas affected by glacial isostatic adjustment (GIA) generally show uplift after deglaciation. These regions are also characterized by a moderate past and present-day seismicity, at seismic moment release rates that exceed those expected under stable tectonic conditions. Several faults have been found in North America and Europe, which have been activated during or after the last deglaciation. Large-magnitude earthquakes have generated fault offsets of up to 120 m. Due to the recent melting of Greenland and Antarctic ice sheets, an understanding of the occurrence of these earthquakes is important. With a new finite-element model, we are able to estimate, for the first time, fault slip during a glacial cycle for continental ice sheets. A two-dimensional earth model based on former GIA studies is developed, which is loaded with a hyperbolic ice sheet. The fault is able to move in a stress field consisting of rebound stress, tectonic background stress, and lithostatic stress. The sensitivity of this fault is tested regarding lithospheric and crustal thickness, viscosity structure of upper and lower mantle, ice-sheet thickness and width, and fault parameters including coefficient of friction, depth, angle and location. Fault throws of up to 30 m are obtained using a fault of 45° dipping below the ice sheet centre. The thickness of the crust is one of the major parameters affecting the total fault throw, e.g. higher values for a thinner crust. Most faults start to move close to the end of deglaciation, and movement stops after one thrusting/reverse earthquake. However, certain conditions may also lead to several fault movements after the end of glaciations.

  4. 3D Velocity Structure of Chukou Fault Area, Taiwan from Seismic Tomography

    NASA Astrophysics Data System (ADS)

    Chen, C.; Chang, W.; Jian, W.

    2009-12-01

    In this study, we used the seismic data that recorded by the broadband stations which deployed around the Chukou fault area, Taiwan. We have chosen 1661 earthquake events with high quality records in this research. The waveform cross correlation technique is applied to calculate the 143086 pairs of waveform data. By combining with data from the seismic catalog, there are 342202 absolute travel-time pairs through the double difference tomography method to relocate the seismicity and invert the 3D velocity structures beneath the Chukou fault area. Due to Taiwan Island is located in an active boundary zone between the Eurasia continental and Philippine Sea plates, the violent collision between the two plates which causes a series of imbricate fold-thrust belts to form between the western foothills and the coastal plain. The Chukou fault is just the boundary between the fold-thrust belts and the coastal plain in the Chia-Nan area, Taiwan. The seismotectonic structure beneath this area is more complex. From many studies, velocity structure can be used as an indicator of the geometry of fault and the general aspect of tectonics. Therefore, the first goal of this research is to analyze the degree of correlation between the velocity structure and the characteristics of seismicity and the tectonic implications of the area. The second intention is to study the distribution of seismic events and its association with fault activities. Our results indicate that the variation of velocity structure beneath fault area is caused by local geological structures, complex fault crossing. We also find that most earthquakes occur in the area that has Vp/Vs gradient varying rapidly. Finally, both using catalog and cross-correlation data in the inversion procedure are not only exhibit better resolution, but also can obtain the detail 3D velocity structure beneath the fault zone.

  5. Generation and propagation of stick-slip waves over a fault with rate-independent friction

    NASA Astrophysics Data System (ADS)

    Karachevtseva, Iuliia; Dyskin, Arcady; Pasternak, Elena

    2014-05-01

    Earthquakes generated at faults are either produced by rapid (sometimes supersonic) propagation of shear cracks/ruptures along the fault or originated in the stick-slip sliding over the fault. In some cases, supersonic (faster than the shear wave velocity) propagation of earthquake-generating shear ruptures or sliding is observed. This gave rise to the concept of supersonic shear crack propagation, much researched in the literature. Here we consider another mechanisms of supersonic sliding propagation. We concentrate on the stick-slip sliding as the earthquake mechanism. It is conventionally assumed that the mechanism of stick-slip lies in intermittent change between static and kinetic friction and the rate dependence of the friction coefficient. However the accumulation of elastic energy in the sliding plates on both sides of the fault can produce oscillations in the velocity of sliding even if the friction coefficient is constant. These oscillations resemble stick-slip movement, but they manifest themselves in terms of sliding velocity rather than displacement. Furthermore, over long faults the sliding exhibits wave-like propagation. We developed a model that shows that the zones of non-zero sliding velocities propagate along the fault with the velocity of p-wave. The mechanism of such fast movement is in the fact that sliding of every element of the rock at the fault surface creates normal (tensile/compressive) stresses in the neighbouring elements (normal stresses on the planes normal to the fault surface). The strains associated with these stresses are controlled by the Young's modulus rather than shear modulus resulting in the p-wave velocity of propagation of the sliding zone. This results in the observed supersonic (with respect to the s-waves) propagation of the apparent shear rupture. Keywords: Stick-slip, Rate-independent friction, Supersonic propagation.

  6. Time-Dependent Coulomb Stres along the San Andreas Fault System

    NASA Astrophysics Data System (ADS)

    Smith, B. R.; Sandwell, D. T.

    2003-12-01

    Many questions remain regarding the evolution of stress along the San Andreas Fault System: Which segments of the San Andreas System are approaching failure? What is the stress interaction along different fault segments for likely slip scenarios? To what extent does locking depth influence the regional stress field? To better address these questions, we have developed and tested a semi-analytic, time-dependent model for 3-D displacement and stress caused by a dislocation in an elastic layer over a viscoelastic half-space. Our model is remarkably efficient: a single time-step computation of 2048 by 2048 horizontal grid cells, containing over 400 fault elements within a 900 x 1700 km fault zone, requires approximately 1 minute of CPU time on an ordinary workstation. This speed enables us to rapidly explore various full 3-D viscoelastic models with realistic 1000-year faulting scenarios. Our approach for investigating time-dependent deformation and stress evolution of the San Andreas Fault System is as follows: We represent far-field plate motion by continuous slip in the lower portion of a 50 km thick elastic layer. Earthquakes are modeled by episodic slip along individual faults using spatially-variable locking depth and geologically-estimated recurrence intervals. Each co-seismic event results in an instantaneous change of stress within the viscoelastic half-space that slowly relaxes with time and is coupled with the evolution of stresses within the elastic plate. We investigate such evolving stresses by computing time-dependent Coulomb stress within the seismogenic zone. We find that the evolving stress field is sensitive to plate thickness, half-space viscosity, and faulting scenario. We are currently establishing a suite of models, consistent with both geodetic and geological observations, that will increase our understanding of how temporal plate-boundary deformation and stress variations within the seismogenic crust can result from different tectonic settings throughout the earthquake cycle.

  7. Kanda fault: A major seismogenic element west of the Rukwa Rift (Tanzania, East Africa)

    NASA Astrophysics Data System (ADS)

    Vittori, Eutizio; Delvaux, Damien; Kervyn, François

    1997-09-01

    The NW-SE trending Rukwa Rift, part of the East African Rift System, links the approximately N-S oriented Tanganyika and Nyassa (Malawi) depressions. The rift has a complex half-graben structure, generally interpreted as the result of normal and strike-slip faulting. Morphological and structural data (e.g. fault scarps, faceted spurs, tilting of Quaternary continental deposits, volcanism, seismicity) indicate Late Quaternary activity within the rift. In 1910 an earthquake of M = 7.4 (historically the largest felt in Africa) struck the Rukwa region. The epicentre was located near the Kanda fault, which affects the Ufipa plateau, separating the Rukwa depression from the south-Tanganyika basin. The geomorphic expression of the Kanda fault is a prominent fresh-looking scarp more than 180 km long, from Tunduma to north of Sumbawanga, that strikes roughly NW-SE, and dips constantly northeast. No evidence for horizontal slip was observed. Generally, the active faulting affects a very narrow zone, and is only locally distributed over several subparallel scarps. The height of the scarp progressively decreases towards the northwest, from about 40-50 m to a few metres north of Sumbawanga. Faulted lacustrine deposits exposed in a road cut near Kaengesa were dated as 8340 ± 700 and 13 600 ± 1240 radiocarbon years. These low-energy deposits now hang more than 15 m above the present-day valley floor, suggesting rapid uplift during the Holocene. Due to its high rate of activity in very recent times, the Kanda Fault could have produced the 1910 earthquake. Detailed paleoseismological studies are used to characterize its recent history. In addition, the seismic hazard posed by this fault, which crosses the fast growing town of Sumbawanga, must be seriously considered in urban planning.

  8. A poroplastic model of mature fault cores with biphasic pore fluids to investigate the role of gas on the onset of fault failure

    NASA Astrophysics Data System (ADS)

    Maury, V.; Fitzenz, D. D.; Piau, J.

    2011-12-01

    A poroplastic model of mature fault cores with biphasic pore fluids to investigate the role of gas on the onset of fault failure The effects of a rapid access of a fault to a source of overpressured fluids on effective stress and failure criterion have been recognized for a long time (Quattrocchi 1999), resulting in a decrease of the effective stress. We concentrate here on the case of the appearance/disappearance of gas in the pore fluid, and its effects on the loading path (Maury et al., 2011). Indeed, gas can appear continuously in a fault zone through dilatant deformation of the zones adjacent to the core fault (Kuo, 2006 ), due to fluid depressurization and degassing. Other source of gas e.g., mantle degasing (Miller et al, 2004), devolitization of coal or other organic matter during frictional sliding (O'Hara et al, 2006), may be remote, and diffuse through a fracture network, or local. Gas in a fault core reduces the Skempton's coefficient to almost 0, the total stress increase during tectonic loading induces a larger increase in effective stress than when pore fluid is fully liquid saturated, thus changing dramatically the loading path for that fault. Not only is failure delayed, but the shear stress at failure increases significantly. Before gas disappearance, the fault might not be critically stressed. However, a subsequent disappearance of gas may lead to failure for small increments of normal and shear stress: apparently strong faults can fail in response to small stress changes. Dilatant failure envelopes are often assumed for localized faults, whereas end-cap envelopes are usually used in association with compaction bands. Here we investigate a poroplastic model for mature fault cores acknowledging that these can be dilatant/contractant according to the state of stress at the plasticity criterion contact. We therefore use a Cam-Clay model as a first approximation. This model enables us to monitor the stability behavior and compute the jumps in stress, pore pressure, and displacements at the fault core during tectonic loading imposed as displacements in the far-field, with or without pressurization by an external source of fluids, and for varying pore fluid compressibilities. We use the model to identify key measurable properties indicative of the fault behavior, and we review documented cases of earthquake triggering at low stress changes to check the importance of gas on the onset of stable/unstable failure on real faults. Kieran O'Hara, Kazuo Mizoguchi, Toshihiko Shimamoto and J.C. Hower Experimental frictional heating of coal gouge at seismic slip rates: Evidence for devolatilization and thermal pressurization of gouge fluidsTectonophysics, Vol. 424, Iss. 1-2, 19 09 2006, Pages 109-118, doi:10.1016/j.tecto.2006.07.007 | Kuo, MCT., Fan, K. & al. A mechanism for anomalous decline in radon precursory to an earthquake Ground Water 44 (5): 642-647 sep-oct 2006 Maury V., Piau J.-M., Fitzenz D., Mechanical effect of the presence of gas on faults modeled as a sandwiched Cam-Clay material, Proc. XIIth Intern. Cong. For Rock Mechanics, Beijin Oct. 2011 Balkema Pub. (at press) Quattrocchi 1999, Annali di Geofisica Vol 42 N4 1999

  9. South Virgin-White Hills detachment fault system of SE Nevada and NW Arizona: Applying apatite fission track thermochronology to constrain the tectonic evolution of a major continental detachment fault

    NASA Astrophysics Data System (ADS)

    Fitzgerald, Paul G.; Duebendorfer, Ernest M.; Faulds, James E.; O'Sullivan, Paul

    2009-04-01

    The South Virgin-White Hills detachment (SVWHD) in the central Basin and Range province with an along-strike extent of ˜60 km is a major continental detachment fault system. Displacement on the SVWHD decreases north to south from ˜17 to <6 km. This is accompanied by a change in fault and footwall rock type from mylonite overprinted by cataclasite to chlorite cataclasite and then fault breccia reflecting decreasing fault displacement and footwall exhumation. Apatite fission track (AFT) thermochronology was applied both along-strike and across-strike to assess this displacement gradient. The overall thermal history reflects Laramide cooling (˜75 Ma) and then rapid cooling beginning in the late early Miocene. Age patterns reflect some complexity but extension along the SVWHD appears synchronous with rapid cooling initiated at ˜17 Ma due to tectonic exhumation. Slip rate is more rapid (˜8.6 km/Ma) in the north compared to ˜1 km/Ma in the south. The displacement gradient results from penecontemporaneous along-strike motion and formation of the SVWHD by linkage of originally separate fault segments that have differential displacements and hence differential slip rates. East-west transverse structures likely play a role in linkage of different fault segments. The preextension paleogeothermal gradient is well constrained in the Gold Butte block as 18-20°C/km. We present a new thermochronologic approach to constrain fault dip during slip, treating the vertical exhumation rate and the slip as vectors, with the angle between them used to constrain fault dip during slip through the closure temperature of a particular thermochronometer. AFT data from the western rim of the Colorado Plateau constrain the initiation of timing of cooling associated with the Laramide Orogeny at ˜75 Ma, and a reheating event in the late Eocene/early Oligocene associated with burial by sediments ("rim gravels") most likely shed from the Kingman High to the west of the plateau.

  10. The width of fault zones in a brittle-viscous lithosphere: Strike-slip faults

    NASA Technical Reports Server (NTRS)

    Parmentier, E. M.

    1991-01-01

    A fault zone in an ideal brittle material overlying a very weak substrate could, in principle, consist of a single slip surface. Real fault zones have a finite width consisting of a number of nearly parallel slip surfaces on which deformation is distributed. The hypothesis that the finite width of fault zones reflects stresses due to quasistatic flow in the ductile substrate of a brittle surface layer is explored. Because of the simplicity of theory and observations, strike-slip faults are examined first, but the analysis can be extended to normal and thrust faulting.

  11. On-Board Real-Time State and Fault Identification for Rovers

    NASA Technical Reports Server (NTRS)

    Washington, Richard

    2000-01-01

    For extended autonomous operation, rovers must identify potential faults to determine whether its execution needs to be halted or not. At the same time, rovers present particular challenges for state estimation techniques: they are subject to environmental influences that affect senior readings during normal and anomalous operation, and the sensors fluctuate rapidly both because of noise and because of the dynamics of the rover's interaction with its environment. This paper presents MAKSI, an on-board method for state estimation and fault diagnosis that is particularly appropriate for rovers. The method is based on a combination of continuous state estimation, wing Kalman filters, and discrete state estimation, wing a Markov-model representation.

  12. Self-stabilizing byzantine-fault-tolerant clock synchronization system and method

    NASA Technical Reports Server (NTRS)

    Malekpour, Mahyar R. (Inventor)

    2012-01-01

    Systems and methods for rapid Byzantine-fault-tolerant self-stabilizing clock synchronization are provided. The systems and methods are based on a protocol comprising a state machine and a set of monitors that execute once every local oscillator tick. The protocol is independent of specific application specific requirements. The faults are assumed to be arbitrary and/or malicious. All timing measures of variables are based on the node's local clock and thus no central clock or externally generated pulse is used. Instances of the protocol are shown to tolerate bursts of transient failures and deterministically converge with a linear convergence time with respect to the synchronization period as predicted.

  13. Intermittent/transient fault phenomena in digital systems

    NASA Technical Reports Server (NTRS)

    Masson, G. M.

    1977-01-01

    An overview of the intermittent/transient (IT) fault study is presented. An interval survivability evaluation of digital systems for IT faults is discussed along with a method for detecting and diagnosing IT faults in digital systems.

  14. New mapping and structural constraints on the Queen Charlotte-Fairweather Fault system, southeast Alaska

    NASA Astrophysics Data System (ADS)

    Levoir, M. A.; Roland, E. C.; Gulick, S. P.; Haeussler, P. J.; Christeson, G. L.; Van Avendonk, H. J.

    2013-12-01

    The dextral Queen Charlotte-Fairweather Fault lies along the western margin of Canada and southeastern Alaska, a transform plate boundary accommodating motion between the North American and Pacific Plates. The Fairweather Fault is the northern extension of the Queen Charlotte Fault and has numerous and complex splays, including the Chichagof-Baranof Fault, the Peril Strait Fault, the Chatham Strait Fault, and the Icy Point-Lituya Bay Fault. Except for a few small areas, these fault systems have not been mapped in detail. We present updated geometries and fault maps of the entirety of the strike-slip system using seismic reflection and bathymetric data, including a 2004 seismic reflection survey (EW0408), 2005 United Nations Commission on Law of the Sea multibeam bathymetry, and legacy data from the U.S. Geological Survey (USGS) and the National Geophysical Data Center. This work is highly relevant for earthquake hazard research and mitigation in southeast Alaska. Several large (> Mw 7.0) earthquakes have occurred along this margin in the last century, impacting communities of southeastern Alaska and western Canada. Two large, recent events include 1) a Mw 7.7 earthquake that took place on 28 October 2012 near the Haida Gwaii Islands offshore of western Canada, and 2) a Mw 7.5 event which occurred on 05 January 2013, 330 km to the northwest and offshore of Craig, Alaska. Interestingly, the Haida Gwaii earthquake ruptured as a thrust event and the Craig earthquake ruptured with a near-vertical dextral strike-slip mechanism. Since a change in Pacific Plate motion around 4 million years ago, the southern Queen Charlotte Fault system has been obliquely converging at a rate of 20 mm/year, with the boundary accommodating about 80 km of perpendicular motion over that time. This convergence explains the Haida Gwaii thrust earthquake, but leaves questions about the along-strike fault structure. Two opposing end-member theories suggest convergence is accommodated by either: 1) Pacific Plate underthrusting beneath North America; or 2) crustal shortening via smaller, localized thrust faults. The underthrusting model assumes oblique slip along fault planes that transition to a lesser dip with increasing depth, whereas the local-thrust model requires strain partitioning via a series of thrust faults proximal to and inland from the main strike-slip trace. We provide insight into this system with improved surficial fault geometries that illuminate Queen Charlotte Fault structure in the context of the two recent earthquakes. We present these data in conjunction with preliminary aftershock locations and focal mechanisms for the 05 January 2013 Craig earthquake (obtained from a joint University of Texas-USGS OBS rapid-response survey), which offer new information about the seemingly changing along-strike dip and planar structure of the southern Queen Charlotte Fault. Additionally, we can now better constrain the Queen Charlotte's northern structure in relation with the Chatham Strait and Fairweather transforms.

  15. The Curiosity Mars Rover's Fault Protection Engine

    NASA Technical Reports Server (NTRS)

    Benowitz, Ed

    2014-01-01

    The Curiosity Rover, currently operating on Mars, contains flight software onboard to autonomously handle aspects of system fault protection. Over 1000 monitors and 39 responses are present in the flight software. Orchestrating these behaviors is the flight software's fault protection engine. In this paper, we discuss the engine's design, responsibilities, and present some lessons learned for future missions.

  16. Intermittent/transient faults in digital systems

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  17. Intraplate rotational deformation induced by faults

    NASA Astrophysics Data System (ADS)

    Dembo, Neta; Hamiel, Yariv; Granot, Roi

    2015-11-01

    Vertical axis rotations provide important constraints on the tectonic history of plate boundaries. Geodetic measurements can be used to calculate interseismic rotations, whereas paleomagnetic remanence directions provide constraints on the long-term rotations accumulated over geological timescales. Here we present a new mechanical modeling approach that links between intraplate deformational patterns of these timescales. We construct mechanical models of active faults at their locked state to simulate the presumed to be elastic interseismic deformation rate observed by GPS measurements. We then apply a slip to the faults above the locking depth to simulate the long-term deformation of the crust from which we derive the accumulated rotations. We test this approach in northern Israel along the Dead Sea Fault and Carmel-Gilboa fault system. We use 12 years of interseismic GPS measurements to constrain a slip model of the major faults found in this region. Next, we compare the modeled rotations against long-term rotations determined based on new primary magnetic remanence directions from 29 sites with known age. The distributional pattern of site mean declinations is in general agreement with the vertical axis rotations predicted by the mechanical model, both showing anomalously high rotations near fault tips and bending points. Overall, the results from northern Israel validate the effectiveness of our approach and indicate that rotations induced by motion along faults may act in parallel (or alone) to rigid block rotations. Finally, the new suggested method unravels important insights on the evolution (timing, magnitude, and style) of deformation along major faults.

  18. Training for Skill in Fault Diagnosis

    ERIC Educational Resources Information Center

    Turner, J. D.

    1974-01-01

    The Knitting, Lace and Net Industry Training Board has developed a training innovation called fault diagnosis training. The entire training process concentrates on teaching based on the experiences of troubleshooters or any other employees whose main tasks involve fault diagnosis and rectification. (Author/DS)

  19. The cost of software fault tolerance

    NASA Technical Reports Server (NTRS)

    Migneault, G. E.

    1982-01-01

    The proposed use of software fault tolerance techniques as a means of reducing software costs in avionics and as a means of addressing the issue of system unreliability due to faults in software is examined. A model is developed to provide a view of the relationships among cost, redundancy, and reliability which suggests strategies for software development and maintenance which are not conventional.

  20. Deltaic faulting and subsidence: Analog modeling

    SciTech Connect

    Larroque, J.M. )

    1991-03-01

    Scaled experiments with sand layers overlying viscous silicone putty have been used to investigate the behavior of deltaic sediments prograding over salt or mobile shales. Differential loading caused by a sand wedge prograding over a viscous putty layer induces a forward expulsion of the viscous material. This causes the putty to thin beneath the sand wedge and to thicken at the wedge toe. It results in extension and subsidence in the sand wedge. The predominant dip of the extensional faults is in the progradation direction except in the toe bulge area where a major fault may occur with an opposite (counter regional dip). The experiments examined how changes in model parameters affect the resultant fault geometries: Increasing the putty thickness leads to increase in the amount of extension and degree of block rotation, both of which decrease upwards into younger sediments; a sloping basement/putty interface leads to a significant increase in the extension of the sand wedge; fast progradation rates lead to widely spaced faulting whereas slow progradation rates lead to closely spaced faulting; basement fault steps, associated with changes in viscous layer thickness, are also demonstrated to locate and locally reorient faults in the overlying sand wedge. These concepts can assist the interpreter in defining the shape of faulted traps, particularly at depth or where seismic quality deteriorates, and in understanding the evolution and timing of trap formation.

  1. Fault detection with principal component pursuit method

    NASA Astrophysics Data System (ADS)

    Pan, Yijun; Yang, Chunjie; Sun, Youxian; An, Ruqiao; Wang, Lin

    2015-11-01

    Data-driven approaches are widely applied for fault detection in industrial process. Recently, a new method for fault detection called principal component pursuit(PCP) is introduced. PCP is not only robust to outliers, but also can accomplish the objectives of model building, fault detection, fault isolation and process reconstruction simultaneously. PCP divides the data matrix into two parts: a fault-free low rank matrix and a sparse matrix with sensor noise and process fault. The statistics presented in this paper fully utilize the information in data matrix. Since the low rank matrix in PCP is similar to principal components matrix in PCA, a T2 statistic is proposed for fault detection in low rank matrix. And this statistic can illustrate that PCP is more sensitive to small variations in variables than PCA. In addition, in sparse matrix, a new monitored statistic performing the online fault detection with PCP-based method is introduced. This statistic uses the mean and the correlation coefficient of variables. Monte Carlo simulation and Tennessee Eastman (TE) benchmark process are provided to illustrate the effectiveness of monitored statistics.

  2. 40 CFR 258.13 - Fault areas.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Fault areas. 258.13 Section 258.13 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES CRITERIA FOR MUNICIPAL SOLID WASTE LANDFILLS Location Restrictions § 258.13 Fault areas. (a) New MSWLF units and...

  3. 40 CFR 258.13 - Fault areas.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Fault areas. 258.13 Section 258.13 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES CRITERIA FOR MUNICIPAL SOLID WASTE LANDFILLS Location Restrictions § 258.13 Fault areas. (a) New MSWLF units and...

  4. 40 CFR 258.13 - Fault areas.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Fault areas. 258.13 Section 258.13 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES CRITERIA FOR MUNICIPAL SOLID WASTE LANDFILLS Location Restrictions § 258.13 Fault areas. (a) New MSWLF units and...

  5. 40 CFR 258.13 - Fault areas.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Fault areas. 258.13 Section 258.13 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES CRITERIA FOR MUNICIPAL SOLID WASTE LANDFILLS Location Restrictions § 258.13 Fault areas. (a) New MSWLF units and...

  6. 40 CFR 258.13 - Fault areas.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 26 2012-07-01 2011-07-01 true Fault areas. 258.13 Section 258.13 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES CRITERIA FOR MUNICIPAL SOLID WASTE LANDFILLS Location Restrictions § 258.13 Fault areas. (a) New MSWLF units and...

  7. Interactive Instruction in Solving Fault Finding Problems.

    ERIC Educational Resources Information Center

    Brooke, J. B.; And Others

    1978-01-01

    A training program is described which provides, during fault diagnosis, additional information about the relationship between the remaining faults and the available indicators. An interactive computer program developed for this purpose and the first results of experimental training are described. (Author)

  8. Diagnostics Tools Identify Faults Prior to Failure

    NASA Technical Reports Server (NTRS)

    2013-01-01

    Through the SBIR program, Rochester, New York-based Impact Technologies LLC collaborated with Ames Research Center to commercialize the Center s Hybrid Diagnostic Engine, or HyDE, software. The fault detecting program is now incorporated into a software suite that identifies potential faults early in the design phase of systems ranging from printers to vehicles and robots, saving time and money.

  9. Tractable particle filters for robot fault diagnosis

    NASA Astrophysics Data System (ADS)

    Verma, Vandi

    Experience has shown that even carefully designed and tested robots may encounter anomalous situations. It is therefore important for robots to monitor their state so that anomalous situations may be detected in a timely manner. Robot fault diagnosis typically requires tracking a very large number of possible faults in complex non-linear dynamic systems with noisy sensors. Traditional methods either ignore the uncertainly or use linear approximations of nonlinear system dynamics. Such approximations are often unrealistic, and as a result faults either go undetected or become confused with non-fault conditions. Probability theory provides a natural representation for uncertainty, but an exact Bayesian solution for the diagnosis problem is intractable. Classical Monte Carlo methods, such as particle filters, suffer from substantial computational complexity. This is particularly true with the presence of rare, yet important events, such as many system faults. The thesis presents a set of complementary algorithms that provide an approach for computationally tractable fault diagnosis. These algorithms leverage probabilistic approaches to decision theory and information theory to efficiently track a large number of faults in a general dynamic system with noisy measurements. The problem of fault diagnosis is represented as hybrid (discrete/continuous) state estimation. Taking advantage of structure in the domain it dynamically concentrates computation in the regions of state space that are currently most relevant without losing track of less likely states. Experiments with a dynamic simulation of a six-wheel rocker-bogie rover show a significant improvement in performance over the classical approach.

  10. Late Cenozoic intraplate faulting in eastern Australia

    NASA Astrophysics Data System (ADS)

    Babaahmadi, Abbas; Rosenbaum, Gideon

    2014-12-01

    The intensity and tectonic origin of late Cenozoic intraplate deformation in eastern Australia is relatively poorly understood. Here we show that Cenozoic volcanic rocks in southeast Queensland have been deformed by numerous faults. Using gridded aeromagnetic data and field observations, structural investigations were conducted on these faults. Results show that faults have mainly undergone strike-slip movement with a reverse component, displacing Cenozoic volcanic rocks ranging in ages from ˜31 to ˜21 Ma. These ages imply that faulting must have occurred after the late Oligocene. Late Cenozoic deformation has mostly occurred due to the reactivation of major faults, which were active during episodes of basin formation in the Jurassic-Early Cretaceous and later during the opening of the Tasman and Coral Seas from the Late Cretaceous to the early Eocene. The wrench reactivation of major faults in the late Cenozoic also gave rise to the occurrence of brittle subsidiary reverse strike-slip faults that affected Cenozoic volcanic rocks. Intraplate transpressional deformation possibly resulted from far-field stresses transmitted from the collisional zones at the northeast and southeast boundaries of the Australian plate during the late Oligocene-early Miocene and from the late Miocene to the Pliocene. These events have resulted in the hitherto unrecognized reactivation of faults in eastern Australia.

  11. A Game Theoretic Fault Detection Filter

    NASA Technical Reports Server (NTRS)

    Chung, Walter H.; Speyer, Jason L.

    1995-01-01

    The fault detection process is modelled as a disturbance attenuation problem. The solution to this problem is found via differential game theory, leading to an H(sub infinity) filter which bounds the transmission of all exogenous signals save the fault to be detected. For a general class of linear systems which includes some time-varying systems, it is shown that this transmission bound can be taken to zero by simultaneously bringing the sensor noise weighting to zero. Thus, in the limit, a complete transmission block can he achieved, making the game filter into a fault detection filter. When we specialize this result to time-invariant system, it is found that the detection filter attained in the limit is identical to the well known Beard-Jones Fault Detection Filter. That is, all fault inputs other than the one to be detected (the "nuisance faults") are restricted to an invariant subspace which is unobservable to a projection on the output. For time-invariant systems, it is also shown that in the limit, the order of the state-space and the game filter can be reduced by factoring out the invariant subspace. The result is a lower dimensional filter which can observe only the fault to be detected. A reduced-order filter can also he generated for time-varying systems, though the computational overhead may be intensive. An example given at the end of the paper demonstrates the effectiveness of the filter as a tool for fault detection and identification.

  12. Is the Lishan fault of Taiwan active?

    NASA Astrophysics Data System (ADS)

    Kuo-Chen, Hao; Wu, Francis; Chang, Wu-Lung; Chang, Chih-Yu; Cheng, Ching-Yu; Hirata, Naoshi

    2015-10-01

    The Lishan fault has been characterized alternately as a major discontinuity in stratigraphy, structures and metamorphism, a ductile shear zone, a tectonic suture or non-existent. In addition to being a geological boundary, it also marks transitions in subsurface structures. Thus, the seismicity to the west of the fault permeates through the upper and mid-crust while beneath the Central Range it is noticeably less and largely concentrated in the upper 12 km. A prominent west-dipping conductive zone extends upward to meet the Lishan fault. Also, the eastward increase of crust thickness from ~ 30 km in the Taiwan Strait quickens under the Lishan fault to form a root of over 50 km under the Central Range. In the past, the small magnitude seismicity along the Lishan fault has been noticed but is too diffuse for definitive association with the fault. Recent processing of aftershock records of the 1999 Mw 7.6 Chi-Chi earthquake using Central Weather Bureau data and, especially, data from three post-Chi-Chi deployments of seismic stations across central Taiwan yielded hypocenters that appear to link directly to the Lishan structure. The presence of a near 4-km-long vertical seismic zone directly under the surface trace of the Lishan fault indicates that it is an active structure from the surface down to about 35 km, and the variety of focal mechanisms indicates that the fault motion can be complex and depth-dependent.

  13. Active faulting in the Walker Lane

    NASA Astrophysics Data System (ADS)

    Wesnousky, Steven G.

    2005-06-01

    Deformation across the San Andreas and Walker Lane fault systems accounts for most relative Pacific-North American transform plate motion. The Walker Lane is composed of discontinuous sets of right-slip faults that are located to the east and strike approximately parallel to the San Andreas fault system. Mapping of active faults in the central Walker Lane shows that right-lateral shear is locally accommodated by rotation of crustal blocks bounded by steep-dipping east striking left-slip faults. The left slip and clockwise rotation of crustal blocks bounded by the east striking faults has produced major basins in the area, including Rattlesnake and Garfield flats; Teels, Columbus and Rhodes salt marshes; and Queen Valley. The Benton Springs and Petrified Springs faults are the major northwest striking structures currently accommodating transform motion in the central Walker Lane. Right-lateral offsets of late Pleistocene surfaces along the two faults point to slip rates of at least 1 mm/yr. The northern limit of northwest trending strike-slip faults in the central Walker Lane is abrupt and reflects transfer of strike-slip to dip-slip deformation in the western Basin and Range and transformation of right slip into rotation of crustal blocks to the north. The transfer of strike slip in the central Walker Lane to dip slip in the western Basin and Range correlates to a northward broadening of the modern strain field suggested by geodesy and appears to be a long-lived feature of the deformation field. The complexity of faulting and apparent rotation of crustal blocks within the Walker Lane is consistent with the concept of a partially detached and elastic-brittle crust that is being transported on a continuously deforming layer below. The regional pattern of faulting within the Walker Lane is more complex than observed along the San Andreas fault system to the west. The difference is attributed to the relatively less cumulative slip that has occurred across the Walker Lane and that oblique components of displacement are of opposite sense along the Walker Lane (extension) and San Andreas (contraction), respectively. Despite the gross differences in fault pattern, the Walker Lane and San Andreas also share similarities in deformation style, including clockwise rotations of crustal blocks leading to development of structural basins and the partitioning of oblique components of slip onto subparallel strike-slip and dip-slip faults.

  14. Elastodynamic Simulation of Fault System Dynamics

    NASA Astrophysics Data System (ADS)

    Mora, P.; Weatherley, D.

    2002-12-01

    Previous simulations of granular systems subjected to shear with the lattice solid model have exhibited evolution of the stress correlation function in the leadup to large events. While these results provide evidence for a Critical Point-like mechanism in elasto-dynamic systems and the possibility of earthquake forecasting, it remains unclear whether such a mechanism will occur in more realistic models of interacting fault systems or in the real earth. Furthermore, CA simulations suggest that both Self-Organised Critical and Critical Point behaviours are possible depending on the values of tuning parameters. This suggests that even if the the crust does exhibit CP-like behaviour, a given fault system may not depending on the tuning parameters such as fault density, the statistics of fault friction, and dissipation. To progress towards resolving this issue, we develop a 2D fully elasto-dynamic model of parallel interacting faults. Either slip or velocity weakening friction can be defined along faults. Slip weakening friction and a power law distribution of static and dynamic friction coefficients is specified. Numerical shear experiments are conducted in a model with ten parallel interacting faults and fault friction power law exponents of 0.6 and 1.6. The results exhibit a complex evolution of the stress field and a number of interesting features including activity switching between faults and fault segments in the model. The event size distributions are essentially a power law with a slight overabundence of large events. Based upon comparisons with CA simulation results, this suggests the system is in the SOC part of phase space although further analysis is required to confirm this hypothesis. Numerical expriments are now in progress using different fault densities, fault friction statistics and slip weakening distance to study whether or not the model exhibits both critical point and SOC behaviour like the CA models. The model provides a crucial link between CA maps of phase space (e.g. that show regimes of CP or SOC behaviour) and the behaviour of more realistic elasto-dynamic interacting fault system models, and thus, a means to improve understanding of the complex system behaviour of real fault systems and progress towards the goal of a scientific underpinning for earthquake forecasting

  15. Spatial analysis of hypocenter to fault relationships for determining fault process zone width in Japan.

    SciTech Connect

    Arnold, Bill Walter; Roberts, Barry L.; McKenna, Sean Andrew; Coburn, Timothy C. (Abilene Christian University, Abilene, TX)

    2004-09-01

    Preliminary investigation areas (PIA) for a potential repository of high-level radioactive waste must be evaluated by NUMO with regard to a number of qualifying factors. One of these factors is related to earthquakes and fault activity. This study develops a spatial statistical assessment method that can be applied to the active faults in Japan to perform such screening evaluations. This analysis uses the distribution of seismicity near faults to define the width of the associated process zone. This concept is based on previous observations of aftershock earthquakes clustered near active faults and on the assumption that such seismic activity is indicative of fracturing and associated impacts on bedrock integrity. Preliminary analyses of aggregate data for all of Japan confirmed that the frequency of earthquakes is higher near active faults. Data used in the analysis were obtained from NUMO and consist of three primary sources: (1) active fault attributes compiled in a spreadsheet, (2) earthquake hypocenter data, and (3) active fault locations. Examination of these data revealed several limitations with regard to the ability to associate fault attributes from the spreadsheet to locations of individual fault trace segments. In particular, there was no direct link between attributes of the active faults in the spreadsheet and the active fault locations in the GIS database. In addition, the hypocenter location resolution in the pre-1983 data was less accurate than for later data. These pre-1983 hypocenters were eliminated from further analysis.

  16. Partial fault dictionary: A new approach for computer-aided fault localization

    SciTech Connect

    Hunger, A.; Papathanasiou, A.

    1995-12-31

    The approach described in this paper has been developed to address the computation time and problem size of localization methodologies in VLSI circuits in order to speed up the overall time consumption for fault localization. The reduction of the problem to solve is combined with the idea of the fault dictionary. In a pre-processing phase, a possibly faulty area is derived using the netlist and the actual test results as input data. The result is a set of cones originating from each faulty primary output. In the next step, the best cone is extracted for the fault dictionary methodology according to a heuristic formula. The circuit nodes, which are included in the intersection of the cones, are combined to a fault list. This fault list together with the best cone can be used by the fault simulator to generate a small and manageable fault dictionary related to one faulty output. In connection with additional algorithms for the reduction of stimuli and netlist a partial fault dictionary can be set up. This dictionary is valid only for the given faulty device together with the given and reduced stimuli, but offers important benefits: Practical results show a reduction of simulation time and size of the fault dictionary by factors around 100 or even more, depending on the actual circuit and assumed fault. The list of fault candidates is significantly reduced, and the required number of steps during the process of localization is reduced, too.

  17. Geophysical characterization of buried active faults: the Concud Fault (Iberian Chain, NE Spain)

    NASA Astrophysics Data System (ADS)

    Pueyo Anchuela, Óscar; Lafuente, Paloma; Arlegui, Luis; Liesa, Carlos L.; Simón, José L.

    2015-12-01

    The Concud Fault is a ~14-km-long active fault that extends close to Teruel, a city with about 35,000 inhabitants in the Iberian Range (NE Spain). It shows evidence of recurrent activity during Late Pleistocene time, posing a significant seismic hazard in an area of moderate-to-low tectonic rates. A geophysical survey was carried out along the mapped trace of the southern branch of the Concud Fault to evaluate the geophysical signature from the fault and the location of paleoseismic trenches. The survey identified a lineation of inverse magnetic dipoles at residual and vertical magnetic gradient, a local increase in apparent conductivity, and interruptions of the underground sediment structure along GPR profiles. The origin of these anomalies is due to lateral contrast between both fault blocks and the geophysical signature of Quaternary materials located above and directly south of the fault. The spatial distribution of anomalies was successfully used to locate suitable trench sites and to map non-exposed segments of the fault. The geophysical anomalies are related to the sedimentological characteristics and permeability differences of the deposits and to deformation related to fault activity. The results illustrate the usefulness of geophysics to detect and map non-exposed faults in areas of moderate-to-low tectonic activity where faults are often covered by recent pediments that obscure geological evidence of the most recent earthquakes. The results also highlight the importance of applying multiple geophysical techniques in defining the location of buried faults.

  18. The Fault Block Model: A novel approach for faulted gas reservoirs

    SciTech Connect

    Ursin, J.R.; Moerkeseth, P.O.

    1994-12-31

    The Fault Block Model was designed for the development of gas production from Sleipner Vest. The reservoir consists of marginal marine sandstone of Hugine Formation. Modeling of highly faulted and compartmentalized reservoirs is severely impeded by the nature and extent of known and undetected faults and, in particular, their effectiveness as flow barrier. The model presented is efficient and superior to other models, for highly faulted reservoir, i.e. grid based simulators, because it minimizes the effect of major undetected faults and geological uncertainties. In this article the authors present the Fault Block Model as a new tool to better understand the implications of geological uncertainty in faulted gas reservoirs with good productivity, with respect to uncertainty in well coverage and optimum gas recovery.

  19. Fault Detection for Automotive Shock Absorber

    NASA Astrophysics Data System (ADS)

    Hernandez-Alcantara, Diana; Morales-Menendez, Ruben; Amezquita-Brooks, Luis

    2015-11-01

    Fault detection for automotive semi-active shock absorbers is a challenge due to the non-linear dynamics and the strong influence of the disturbances such as the road profile. First obstacle for this task, is the modeling of the fault, which has been shown to be of multiplicative nature. Many of the most widespread fault detection schemes consider additive faults. Two model-based fault algorithms for semiactive shock absorber are compared: an observer-based approach and a parameter identification approach. The performance of these schemes is validated and compared using a commercial vehicle model that was experimentally validated. Early results shows that a parameter identification approach is more accurate, whereas an observer-based approach is less sensible to parametric uncertainty.

  20. Self-triggering superconducting fault current limiter

    DOEpatents

    Yuan, Xing; Tekletsadik, Kasegn

    2008-10-21

    A modular and scaleable Matrix Fault Current Limiter (MFCL) that functions as a "variable impedance" device in an electric power network, using components made of superconducting and non-superconducting electrically conductive materials. The matrix fault current limiter comprises a fault current limiter module that includes a superconductor which is electrically coupled in parallel with a trigger coil, wherein the trigger coil is magnetically coupled to the superconductor. The current surge doing a fault within the electrical power network will cause the superconductor to transition to its resistive state and also generate a uniform magnetic field in the trigger coil and simultaneously limit the voltage developed across the superconductor. This results in fast and uniform quenching of the superconductors, significantly reduces the burnout risk associated with non-uniformity often existing within the volume of superconductor materials. The fault current limiter modules may be electrically coupled together to form various "n" (rows).times."m" (columns) matrix configurations.

  1. Maneuver Classification for Aircraft Fault Detection

    NASA Technical Reports Server (NTRS)

    Oza, Nikunj C.; Tumer, Irem Y.; Tumer, Kagan; Huff, Edward M.

    2003-01-01

    Automated fault detection is an increasingly important problem in aircraft maintenance and operation. Standard methods of fault detection assume the availability of either data produced during all possible faulty operation modes or a clearly-defined means to determine whether the data provide a reasonable match to known examples of proper operation. In the domain of fault detection in aircraft, identifying all possible faulty and proper operating modes is clearly impossible. We envision a system for online fault detection in aircraft, one part of which is a classifier that predicts the maneuver being performed by the aircraft as a function of vibration data and other available data. To develop such a system, we use flight data collected under a controlled test environment, subject to many sources of variability. We explain where our classifier fits into the envisioned fault detection system as well as experiments showing the promise of this classification subsystem.

  2. Classification of Aircraft Maneuvers for Fault Detection

    NASA Technical Reports Server (NTRS)

    Oza, Nikunj; Tumer, Irem Y.; Tumer, Kagan; Huff, Edward M.; Koga, Dennis (Technical Monitor)

    2002-01-01

    Automated fault detection is an increasingly important problem in aircraft maintenance and operation. Standard methods of fault detection assume the availability of either data produced during all possible faulty operation modes or a clearly-defined means to determine whether the data provide a reasonable match to known examples of proper operation. In the domain of fault detection in aircraft, the first assumption is unreasonable and the second is difficult to determine. We envision a system for online fault detection in aircraft, one part of which is a classifier that predicts the maneuver being performed by the aircraft as a function of vibration data and other available data. To develop such a system, we use flight data collected under a controlled test environment, subject to many sources of variability. We explain where our classifier fits into the envisioned fault detection system as well as experiments showing the promise of this classification subsystem.

  3. Classification of Aircraft Maneuvers for Fault Detection

    NASA Technical Reports Server (NTRS)

    Oza, Nikunj C.; Tumer, Irem Y.; Tumer, Kagan; Huff, Edward M.; Clancy, Daniel (Technical Monitor)

    2002-01-01

    Automated fault detection is an increasingly important problem in aircraft maintenance and operation. Standard methods of fault detection assume the availability of either data produced during all possible faulty operation modes or a clearly-defined means to determine whether the data is a reasonable match to known examples of proper operation. In our domain of fault detection in aircraft, the first assumption is unreasonable and the second is difficult to determine. We envision a system for online fault detection in aircraft, one part of which is a classifier that predicts the maneuver being performed by the aircraft as a function of vibration data and other available data. We explain where this subsystem fits into our envisioned fault detection system as well its experiments showing the promise of this classification subsystem.

  4. Faults, fluids, and southeast Missouri MVT deposits

    SciTech Connect

    Clendenin, C.W.

    1993-03-01

    A number of interpretations have been proposed to explain regional Late Paleozoic flow paths responsible for the southeast Missouri Mississippi Valley-type (MVT) deposits. In each interpretation the driving force for regional flow is the Ouachita orogeny. Differences in interpretations stem directly from how faults are treated hydrologically and are possible depending on whether faults are ignored or treated as barriers to flow. Observations and geochemical data are used here to re-examine the paleohydrology of southeast Missouri. Fault style and facies patterns argue against assumptions of any idealized aquifer system. Specific observations show that faults are barriers to and pathways for fluid flow in a hydrologically compartmentalized region. Regional relations further suggest that fluid flow out of the Reelfoot rift was via faults in the Precambrian basement, and new isotope studies support such an interpretation.

  5. Quantifying fault recovery in multiprocessor systems

    NASA Technical Reports Server (NTRS)

    Malek, Miroslaw; Harary, Frank

    1990-01-01

    Various aspects of reliable computing are formalized and quantified with emphasis on efficient fault recovery. The mathematical model which proves to be most appropriate is provided by the theory of graphs. New measures for fault recovery are developed and the value of elements of the fault recovery vector are observed to depend not only on the computation graph H and the architecture graph G, but also on the specific location of a fault. In the examples, a hypercube is chosen as a representative of parallel computer architecture, and a pipeline as a typical configuration for program execution. Dependability qualities of such a system is defined with or without a fault. These qualities are determined by the resiliency triple defined by three parameters: multiplicity, robustness, and configurability. Parameters for measuring the recovery effectiveness are also introduced in terms of distance, time, and the number of new, used, and moved nodes and edges.

  6. Mechanics of distributed fault and block rotation

    NASA Technical Reports Server (NTRS)

    Nur, A.; Scotti, O.; Ron, H.

    1989-01-01

    Paleomagnetic data, structural geology, and rock mechanics are used to explore the validity and significance of the block rotation concept. The analysis is based on data from Northern Israel, where fault slip and spacing are used to predict block rotation; the Mojave Desert, with well documented strike-slip sets; the Lake Mead, Nevada fault system with well-defined sets of strike-slip faults; and the San Gabriel Mountains domain with a multiple set of strike-slip faults. The results of the analysis indicate that block rotations can have a profound influence on the interpretation of geodetic measurments and the inversion of geodetic data. Furthermore, the block rotations and domain boundaries may be involved in creating the heterogeneities along active fault systems which may be responsible for the initiation and termination of earthquake rupture.

  7. Holocene fault scarps in the Western Alps

    NASA Astrophysics Data System (ADS)

    Hippolyte, J. C.

    2003-04-01

    In the Tarentaise Valley, Goguel (1969) had described recent fault scarps. The present work shows that they are normal faults indicating a SE-directed trend of extension in agreement with recent microseismicity data (Sue et al., 1999). It is proposed that they reflect the Quaternary normal reactivation of the "Front du Houiller" thrust fault. In the Belledonne external crystalline massif, Bordet (1970) had observed from helicopter three main fault scarps that he interpreted as active SE-dipping reverse faults. Partly owing to the difficulties of access this area was not visited until now. Field observations reveal that these faults dip in fact 61-68° to the NW, and are normal faults. The faults scarps are 1 to 13 meters high. These faults, together with at least 10 newly discovered conjugate SE-dipping normal fault scarps of 0.5 to 18 meters high, form an about 2 km wide fault zone along the "Synclinal Median" (S.M.) fault. They attest for the activity of this 70 km-long NNE-striking main fault running in the middle of the Belledonne Massif. Its activity is confirmed by major faceted spurs at the La Perche, the La Perrière and the Claran passes, and by ruptures cutting moraines. Other fault scarps are discovered in the whole Belledonne massif showing in particular that the Font-de-France fault, a 60 km-long SE-dipping fault, is also active. All the observed active faults are normal. Their offsets of mountains slopes, of screes and of rock glacier morphologies demonstrate their activity during the Holocene. They indicate a present SE-directed extension in agreement with recent GPS data (Calais et al., 2002). This mapping shows that the present extensional deformation of the Alps is not limited to the west by the "Frontal Pennine thrust" (Sue et al., 1999) but affects also the external Alps. Taking into account focal plane mechanisms, extension affects at least 70 % of the Western Alps. Some scarps have been sampled for Beryllium cosmogenic dating. However extension rates can already be quantified across the S.M. fault zone where fault scarps offset morphologies of rock glaciers that are stabilized since the end of the Dryas. There a total post-Dryas (10 ka) SE-extension of 15 meters indicates a minimum 1.5 mm/yr average extension rate. Considering that the total mountain slope offsets give a SE-extension of 42 meters, an upper age limit of about 30 ka is estimated for these scarps. This age shows that relatively old fault scarps can be preserved from erosion in granitic massifs. It suggests that older scarps were eroded during the Wurm II maximum glacial, or that post-glacial uplift has enhance this extension.

  8. Fault analysis of multichannel spacecraft power systems

    NASA Technical Reports Server (NTRS)

    Dugal-Whitehead, Norma R.; Lollar, Louis F.

    1990-01-01

    The NASA Marshall Space Flight Center proposes to implement computer-controlled fault injection into an electrical power system breadboard to study the reactions of the various control elements of this breadboard. Elements under study include the remote power controllers, the algorithms in the control computers, and the artificially intelligent control programs resident in this breadboard. To this end, a study of electrical power system faults is being performed to yield a list of the most common power system faults. The results of this study will be applied to a multichannel high-voltage DC spacecraft power system called the large autonomous spacecraft electrical power system (LASEPS) breadboard. The results of the power system fault study and the planned implementation of these faults into the LASEPS breadboard are described.

  9. Active Fault Topography and Fault Outcrops in the Central Part of the Nukumi fault, the 1891 Nobi Earthquake Fault System, Central Japan

    NASA Astrophysics Data System (ADS)

    Sasaki, T.; Ueta, K.; Inoue, D.; Aoyagi, Y.; Yanagida, M.; Ichikawa, K.; Goto, N.

    2010-12-01

    It is important to evaluate the magnitude of earthquake caused by multiple active faults, taking into account the simultaneous effects. The simultaneity of adjacent active faults are often decided on the basis of geometric distances except for known these paleoseismic records. We have been studied the step area between the Nukumi fault and the Neodani fault, which appeared as consecutive ruptures in the 1891 Nobi earthquake, since 2009. The purpose of this study is to establish innovation in valuation technique of the simultaneity of adjacent active faults in addition to the paleoseismic record and the geometric distance. Geomorphological, geological and reconnaissance microearthquake surveys are concluded. The present work is intended to clarify the distribution of tectonic geomorphology along the Nukumi fault and the Neodani fault by high-resolution interpretations of airborne LiDAR DEM and aerial photograph, and the field survey of outcrops and location survey. The study area of this work is the southeastern Nukumi fault and the northwestern Neodani fault. We interpret DEM using shaded relief map and stereoscopic bird's-eye view made from 2m mesh DEM data which is obtained by airborne laser scanner of Kokusai Kogyo Co., Ltd. Aerial photographic survey is for confirmation of DEM interpretation using 1/16,000 scale photo. As a result of topographic survey, we found consecutive tectonic topography which is left lateral displacement of ridge and valley lines and reverse scarplets along the Nukumi fault and the Neodani fault . From Ogotani 2km southeastern of Nukumi pass which is located at the southeastern end of surface rupture along the Nukumi fault by previous study to Neooppa 9km southeastern of Nukumi pass, we can interpret left lateral topographies and small uphill-facing fault scarps on the terrace surface by detail DEM investigation. These topographies are unrecognized by aerial photographic survey because of heavy vegetation. We have found several new outcrops in this area where the surface ruptures of the 1891 Nobi earthquake have not been known. These outcrops have active fault which cut the layer of terrace deposit and slope deposit to the bottom of present soil layer in common. At the locality of Ogotani outcrop, the humic layer which age is from14th century to 15th century by 14C age dating is deformed by the active fault. The vertical displacement of the humic layer is 0.8-0.9m and the terrace deposit layer below the humic layer is ca. 1.3m. For this reason and the existence of fain grain deposit including AT tephra (28ka) in the footwall of the fault, this fault movement occurred more than once since the last glacial age. We conclude that the surface rupture of Nukumi fault in the 1891 Nobi earthquake is continuous to 9km southeast of Nukumi pass. In other words, these findings indicate that there is 10km parallel overlap zone between the surface rupture of the southeastern end of Nukumi fault and the northwestern end of Neodani fault.

  10. High Resolution Interseismic Velocity Model of the San Andreas Fault From GPS and InSAR

    NASA Astrophysics Data System (ADS)

    Tong, X.; Sandwell, D. T.; Smith-Konter, B. R.

    2011-12-01

    We recover the interseismic deformation along the entire San Andreas Fault System (SAFS) at a spatial resolution of 200 meters by combining InSAR and GPS observations using a dislocation model. Previous efforts to compare 17 different GPS-derived strain rate models of the SAFS shows that GPS data alone cannot uniquely resolve the rapid velocity gradients near faults, which are critical for understanding the along-strike variations in stress accumulation rate and associated earthquake hazard. To improve the near-fault velocity resolution, we integrate new GPS observations with InSAR observations, initially from ALOS (Advanced Land Observation Satellite launched by Japan Aerospace Exploration Agency) ascending data (spanning 2006.5-2010), using a remove/restore approach. More than 1100 interferograms were processed with the newly developed InSAR processing software GMTSAR. The integration uses a dislocation-based velocity model to interpolate the Line-Of-Sight (LOS) velocity at the full resolution of the InSAR data in radar coordinates. The residual between the model and InSAR LOS velocity are stacked and high-pass filtered, then added back to the model. This LOS velocity map covers almost entire San Andreas Fault System (see Figure 1) from Maacama Fault to the north to the Superstition Hills Fault to the south. The average standard deviation of the LOS velocity model ranges from 2 to 4 mm/yr. Our initial results show previously unknown details in along-strike variations in surface fault creep. Moreover, the high resolution velocity field can resolve asperities in these "creeping" sections that are important for understanding moment accumulation rates and seismic hazards. We find that much of the high resolution velocity signal is related to non-tectonic processes (e.g., ground subsidence and uplift) sometimes very close to the fault zone. The near-fault deformation signal extracted from this velocity map can provide tighter constraints on fault slip rates and locking depths of the major fault segments along the SAFS.

  11. Architectural Characteristics and Distribution of Hydromechanical Properties within a Small Strike-Slip Fault Zone in a Carbonates Reservoir: Impact on fault stability, induced seismicity, and leakage during CO2 injection

    NASA Astrophysics Data System (ADS)

    Jeanne, P.; Cappa, F.; Guglielmi, Y.; Rinaldi, A. P.

    2014-12-01

    Within the LSBB National Underground Research Laboratory (France), we performed an in situ multidisciplinary and multi-scale analysis of a small fault zone intersecting a layered carbonates reservoir. The study area is located in a gallery at 250 m depth in the unsaturated and unaltered zone of the reservoir. In order to study the distribution of the fault zone properties, we took advantage of the gallery wall and of three vertical 20 m long boreholes located near the fault core, in the damage zone, and in the host rock. Geological, petrophysical (porosity observations and measurements), geotechnical (Q-value) and geophysical measurements (acoustic velocities, uniaxial compressive strength, electrical resistivity, borehole logging), and injection tests were conducted at various scales. We show that horizontal and vertical variations in hydromechanical properties within the damage zone are related to the initial petrophysical properties of the host rock. In the initial low-porosity and fractured layers, the deformations are accommodated by fractures and micro-cracks extending significantly from the fault core. In these layers, the Young modulus of the rock mass (Em) is low and the permeability of the rock mass (Km) is high. In the initial porous and low fractured layers, deformations are accommodated by micro-mechanical processes resulting in a decrease in micro-porosity near the fault core. There is a rapid attenuation of the damage zone. In these layers, Em is high and Km is low. The seismic signature of this kind of fault is complex and the seismic visibility low making them hard to detect. Finally, to assess fault zone stability in case of CO2 injection and the risk of CO2 leakage through the fault itself, we performed some geomechanical numerical simulations and some field hydromechanical tests. We show that the presence of hydromechanical heterogeneity favors the fluid accumulation but strengthen the fault zone and impede fluid migration upward along the fault.

  12. Methodology for Designing Fault-Protection Software

    NASA Technical Reports Server (NTRS)

    Barltrop, Kevin; Levison, Jeffrey; Kan, Edwin

    2006-01-01

    A document describes a methodology for designing fault-protection (FP) software for autonomous spacecraft. The methodology embodies and extends established engineering practices in the technical discipline of Fault Detection, Diagnosis, Mitigation, and Recovery; and has been successfully implemented in the Deep Impact Spacecraft, a NASA Discovery mission. Based on established concepts of Fault Monitors and Responses, this FP methodology extends the notion of Opinion, Symptom, Alarm (aka Fault), and Response with numerous new notions, sub-notions, software constructs, and logic and timing gates. For example, Monitor generates a RawOpinion, which graduates into Opinion, categorized into no-opinion, acceptable, or unacceptable opinion. RaiseSymptom, ForceSymptom, and ClearSymptom govern the establishment and then mapping to an Alarm (aka Fault). Local Response is distinguished from FP System Response. A 1-to-n and n-to- 1 mapping is established among Monitors, Symptoms, and Responses. Responses are categorized by device versus by function. Responses operate in tiers, where the early tiers attempt to resolve the Fault in a localized step-by-step fashion, relegating more system-level response to later tier(s). Recovery actions are gated by epoch recovery timing, enabling strategy, urgency, MaxRetry gate, hardware availability, hazardous versus ordinary fault, and many other priority gates. This methodology is systematic, logical, and uses multiple linked tables, parameter files, and recovery command sequences. The credibility of the FP design is proven via a fault-tree analysis "top-down" approach, and a functional fault-mode-effects-and-analysis via "bottoms-up" approach. Via this process, the mitigation and recovery strategy(s) per Fault Containment Region scope (width versus depth) the FP architecture.

  13. Effects of Late Cretaceous and Cenozoic faulting on the geology and hydrology of the coastal plain near the Savannah River, Georgia and South Carolina

    USGS Publications Warehouse

    Faye, R.E.; Prowell, D.C.

    1982-01-01

    Geologic and hydrologic investigations by the U.S. Geological Survey have defined stratigraphic and hydraulic anomalies suggestive of faulting within Coastal Plain sediments between the Ogeechee River in east-central Georgia and the Edisto River in west-central South Carolina. Examination of borehole cuttings, cores, and geophysical logs from test wells indicate that Triassic rocks and Upper Cretaceous and lower Tertiary Coastal Plain sediments near the Barnwell-Allendale County line near Millett, South Carolina, are offset by a northeast-trending fault downthrown to the northwest. The location of this suspected Coastal Plain fault generally coincides with the location of an inferred fault in basement rocks as interpreted from aeromagnetic surveys. Apparent vertical offsets range from about 700 feet at the base of Upper Cretaceous sediments to about 20 feet in strata of Late Eocene age. As a result, the Upper Cretaceous Middendorf Formation which directly overlies crystalline and Triassic rocks updip (northwest) of this fault, is absent immediately downdip of the fault. The thickness of Tipper Cretaceous sediments is also sharply reduced from about 700 feet to about 180 feet across the fault. Sediments of the basal Coastal Plain aquifer are largely truncated by uplifted Triassic rocks at the fault near Millett, South Carolina. Lateral ground-water flow near the Savannah River Is consequently disrupted updip of the fault and ground water is transferred vertically into overlying sediments and possibly into the Savannah River. At several locations, abrupt changes in potentiometric head occur across this fault. Computed transmissivity of the basal Coastal Plain aquifer is also radically reduced downdip of the fault, sharply reversing a downdip trend of rapidly increasing aquifer transmissivity. Other anomalous potentiometric data along a northeast-trending line between Statesboro, Georgia, and Fairfax, South Carolina, suggest the possibility of similar faulting in correlative geologic units. The location of the suspected fault near Statesboro, Georgia, generally coincides with the eastward extension of the Gulf Trough, a regional potentiometric anomaly in central Georgia.

  14. Fault-zone seals in offshore Trinidad oil fields

    SciTech Connect

    Gibson, R.G. )

    1991-03-01

    Hydrocarbon columns in Pliocene sands of offshore SE Trinidad occur in 3-way closure, primarily in the footwall of normal faults. Multiple reservoir sands and numerous fault blocks result in a large number of individual hydrocarbon accumulations. Fault-plane sections demonstrate that fault sealing is unrelated to juxtaposition of intercalated shales. These fault-zone capillary seals were studied by (1) inferring their fluid-flow properties from the pattern of trapped hydrocarbons and (2) direct examination and measurement of cored faults. Buoyancy pressures for hydrocarbon columns were calculated from fluid property data for each reservoir and fault block. Buoyancy pressures range widely, increasing nonlinearly with fault displacement and percent shale in the faulted section, but do not vary systematically with stratigraphic position or depth. Small-displacement faults observed in core are narrow zones of cataclasis within porous sandstone. Mercury injection tests indicate fault-zone displacement pressures that coincide with buoyancy pressures calculated for hydrocarbon columns sealed by large-displacement faults. The agreement between measured displacement pressures and calculated buoyancy pressures indicates that (1) the reservoirs are filled to their capacity, dictated by the displacement pressure of the fault zones, and (2) the fault-zone seals are primarily the product of deformation of the sands, with some enhancement by incorporation of argillaceous material into the fault zones. The observed relationship between fault displacement and calculated buoyancy pressure of the hydrocarbon columns implies that fault-zone continuity is a factor that needs to be assessed in fault-zone seal analysis.

  15. Reconfigurable fault tolerant avionics system

    NASA Astrophysics Data System (ADS)

    Ibrahim, M. M.; Asami, K.; Cho, Mengu

    This paper presents the design of a reconfigurable avionics system based on modern Static Random Access Memory (SRAM)-based Field Programmable Gate Array (FPGA) to be used in future generations of nano satellites. A major concern in satellite systems and especially nano satellites is to build robust systems with low-power consumption profiles. The system is designed to be flexible by providing the capability of reconfiguring itself based on its orbital position. As Single Event Upsets (SEU) do not have the same severity and intensity in all orbital locations, having the maximum at the South Atlantic Anomaly (SAA) and the polar cusps, the system does not have to be fully protected all the time in its orbit. An acceptable level of protection against high-energy cosmic rays and charged particles roaming in space is provided within the majority of the orbit through software fault tolerance. Check pointing and roll back, besides control flow assertions, is used for that level of protection. In the minority part of the orbit where severe SEUs are expected to exist, a reconfiguration for the system FPGA is initiated where the processor systems are triplicated and protection through Triple Modular Redundancy (TMR) with feedback is provided. This technique of reconfiguring the system as per the level of the threat expected from SEU-induced faults helps in reducing the average dynamic power consumption of the system to one-third of its maximum. This technique can be viewed as a smart protection through system reconfiguration. The system is built on the commercial version of the (XC5VLX50) Xilinx Virtex5 FPGA on bulk silicon with 324 IO. Simulations of orbit SEU rates were carried out using the SPENVIS web-based software package.

  16. Fault failure with moderate earthquakes

    USGS Publications Warehouse

    Johnston, M.J.S.; Linde, A.T.; Gladwin, M.T.; Borcherdt, R.D.

    1987-01-01

    High resolution strain and tilt recordings were made in the near-field of, and prior to, the May 1983 Coalinga earthquake (ML = 6.7, ?? = 51 km), the August 4, 1985, Kettleman Hills earthquake (ML = 5.5, ?? = 34 km), the April 1984 Morgan Hill earthquake (ML = 6.1, ?? = 55 km), the November 1984 Round Valley earthquake (ML = 5.8, ?? = 54 km), the January 14, 1978, Izu, Japan earthquake (ML = 7.0, ?? = 28 km), and several other smaller magnitude earthquakes. These recordings were made with near-surface instruments (resolution 10-8), with borehole dilatometers (resolution 10-10) and a 3-component borehole strainmeter (resolution 10-9). While observed coseismic offsets are generally in good agreement with expectations from elastic dislocation theory, and while post-seismic deformation continued, in some cases, with a moment comparable to that of the main shock, preseismic strain or tilt perturbations from hours to seconds (or less) before the main shock are not apparent above the present resolution. Precursory slip for these events, if any occurred, must have had a moment less than a few percent of that of the main event. To the extent that these records reflect general fault behavior, the strong constraint on the size and amount of slip triggering major rupture makes prediction of the onset times and final magnitudes of the rupture zones a difficult task unless the instruments are fortuitously installed near the rupture initiation point. These data are best explained by an inhomogeneous failure model for which various areas of the fault plane have either different stress-slip constitutive laws or spatially varying constitutive parameters. Other work on seismic waveform analysis and synthetic waveforms indicates that the rupturing process is inhomogeneous and controlled by points of higher strength. These models indicate that rupture initiation occurs at smaller regions of higher strength which, when broken, allow runaway catastrophic failure. ?? 1987.

  17. Robot Position Sensor Fault Tolerance

    NASA Technical Reports Server (NTRS)

    Aldridge, Hal A.

    1997-01-01

    Robot systems in critical applications, such as those in space and nuclear environments, must be able to operate during component failure to complete important tasks. One failure mode that has received little attention is the failure of joint position sensors. Current fault tolerant designs require the addition of directly redundant position sensors which can affect joint design. A new method is proposed that utilizes analytical redundancy to allow for continued operation during joint position sensor failure. Joint torque sensors are used with a virtual passive torque controller to make the robot joint stable without position feedback and improve position tracking performance in the presence of unknown link dynamics and end-effector loading. Two Cartesian accelerometer based methods are proposed to determine the position of the joint. The joint specific position determination method utilizes two triaxial accelerometers attached to the link driven by the joint with the failed position sensor. The joint specific method is not computationally complex and the position error is bounded. The system wide position determination method utilizes accelerometers distributed on different robot links and the end-effector to determine the position of sets of multiple joints. The system wide method requires fewer accelerometers than the joint specific method to make all joint position sensors fault tolerant but is more computationally complex and has lower convergence properties. Experiments were conducted on a laboratory manipulator. Both position determination methods were shown to track the actual position satisfactorily. A controller using the position determination methods and the virtual passive torque controller was able to servo the joints to a desired position during position sensor failure.

  18. Repeated seismic slips recorded in ultracataclastic veins along active faults of the Arima-Takatsuki Tectonic Line, southwest Japan

    NASA Astrophysics Data System (ADS)

    Lin, Aiming; Yamashita, Katsuhiko; Tanaka, Makoto

    2013-03-01

    Field investigations, combined with meso- and microstructural analyses, reveal that numerous ultracataclastic veins are widely developed within a fault zone (<150 m wide) as simple veins, complex lenses, and networks, along active faults of the Arima-Takatsuki Tectonic Line, southwest Japan. These veins comprise mainly pseudotachylyte-like vein and weakly consolidated to unconsolidated fault gouge that is black, dark-brown, brown, gray, and brownish-red in color. Meso- and microstructural features show that these pseudotachylyte-like and fault gouge veins and networks formed during multiple stages, as earlier veins are generally cut and overprinted by younger veins, indicating that the vein-forming events occurred repeatedly and that ultracataclastic material was injected into networks of faults and fractures in the fault zone. The pseudotachylyte-like and fault gouge veins are characterized by an ultrafine- to fine-grained matrix and angular to subangular fragments of host granitic rocks of various sizes, ranging from submicron to millimeters. SEM-EDS (Scanning Electronic Microscope-Energy Dispersive X-ray) and powder X-ray diffraction analyses show that all the ultracataclastic veins are characterized by crystalline materials composed mainly of quartz and feldspar, similar to the host granitic rocks. The present results support the existing hypothesis that ultrafine- to fine-grained materials formed by comminution can be fluidized and injected rapidly into fracture networks located far from the source fault plane in a solid-fluid-gas system during seismic slip; therefore, such materials provide a record of paleoseismic faulting events that occurred repeatedly within the seismogenic fault zone.

  19. Geological and isotopic constraints on the timing of movement in the Tan-Lu Fault Zone, northeastern China

    NASA Astrophysics Data System (ADS)

    Fletcher, C. J. N.; Fitches, W. R.; Rundle, C. C.; Evans, J. A.

    The Tan-Lu Fault Zone forms part of a major fault system which can be traced for over 5000 km parallel to the present Asian continental margin. A sinistral displacement of about 700 km has been postulated on the zone, and it has been argued that this displacement occurred between late Cretaceous and early Tertiary times. However, the geological and isotopic evidence presented in this paper indicate that there was substantial ductile movement on the fault zone during the middle Proterozoic, and that normal faulting was active during the late Proterozoic. In west Shandong Province undeformed late Proterozoic (Qingbaikouan) sediments lie with marked unconformity on Archaean to early Proterozoic schists and gneisses, which contain mylonitic shear zones associated with strike-slip displacements in the fault zone. The Qingbaikouan rocks of this area are comparable to the transgressive sequences of the type area near Beijing. However, syn-depositional fault movements along the Tan-Lu Fault Zone resulted in confined depocentres and rapid facies changes. The limestone micrites at, and near, the bases of some of these sequences are interpreted as calcretes which formed on an irregular landscape. Isotopic studies of the gneisses and schists, within and close to the Tan-Lu Fault Zone, have shown that mineral growth and isotopic resetting were predominantly Precambrian events. Rb-Sr whole-rock data suggest that some of the gneisses first crystallized during the early Proterozoic ( c. 2340 Ma). Biotites and hornblendes from a gneiss within the Tan-Lu Fault Zone gave K-Ar ages between 2342-2059 Ma, a confirmation of this early event. Disturbance of the mineral isotope systems and the growth of muscovite occurred at the end of the middle Proterozoic ( c. 1700 Ma), in response to movement along the Tan-Lu Fault Zone. Whole-rock K-Ar ages of mylonites range from 1025 to 519 Ma, a result of low-temperature hydrothermal alteration, probably no younger than early Palaeozoic.

  20. Knowledge acquisition and rapid protyping of an expert system: Dealing with real world problems

    NASA Technical Reports Server (NTRS)

    Bailey, Patrick A.; Doehr, Brett B.

    1988-01-01

    The knowledge engineering and rapid prototyping phases of an expert system that does fault handling for a Solid Amine, Water Desorbed CO2 removal assembly for the Environmental Control and Life Support System for space based platforms are addressed. The knowledge acquisition phase for this project was interesting because it could not follow the textbook examples. As a result of this, a variety of methods were used during the knowledge acquisition task. The use of rapid prototyping and the need for a flexible prototype suggested certain types of knowledge representation. By combining various techniques, a representative subset of faults and a method for handling those faults was achieved. The experiences should prove useful for developing future fault handling expert systems under similar constraints.

  1. Facies composition and scaling relationships of extensional faults in carbonates

    NASA Astrophysics Data System (ADS)

    Bastesen, Eivind; Braathen, Alvar

    2010-05-01

    Fault seal evaluations in carbonates are challenged by limited input data. Our analysis of 100 extensional faults in shallow-buried layered carbonate rocks aims to improve forecasting of fault core characteristics in these rocks. We have analyzed the spatial distribution of fault core elements described using a Fault Facies classification scheme; a method specifically developed for 3D fault description and quantification, with application in reservoir modelling. In modelling, the fault envelope is populated with fault facies originating from the host rock, the properties of which (e.g. dimensions, geometry, internal structure, petrophysical properties, and spatial distribution of structural elements) are defined by outcrop data. Empirical data sets were collected from outcrops of extensional faults in fine grained, micro-porosity carbonates from western Sinai (Egypt), Central Spitsbergen (Arctic Norway), and Central Oman (Adam Foothills) which all have experienced maximum burial of 2-3 kilometres and exhibit displacements ranging from 4 centimetres to 400 meters. Key observations include fault core thickness, intrinsic composition and geometry. The studied fault cores display several distinct fault facies and facies associations. Based on geometry, fault cores can be categorised as distributed or localized. Each can be further sub-divided according to the presence of shale smear, carbonate fault rocks and cement/secondary calcite layers. Fault core thickness in carbonate rocks may be controlled by several mechanisms: (1) Mechanical breakdown: Irregularities such as breached relays and asperities are broken down by progressive faulting and fracturing to eventually form a thicker fault rock layer. (2) Layer shearing: Accumulations of shale smear along the fault core. (3) Diagenesis; pressure solution, karstification and precipitation of secondary calcite in the core. Observed fault core thicknesses scatter over three orders of magnitude, with a D/T range of 1:1 to 1:1000. In general the complete dataset shows a positive correlation between thickness (T) of fault cores and the displacement (D) on faults. For increasing displacement relationships, the D/T relationship is not constant. The D/T relationship is generally higher for small faults than for larger faults, which implies that comparisons between small and large fault with respect to this parameter should be handled with care. Fault envelope composition, as reflected by the relative proportions of different fault facies in the core, varies with displacement. In small scale faults (0-1 m displacement), secondary calcite layers and fault gouge dominate, whereas shale dominated fault rocks (shale smear) and carbonate dominated fault rocks (breccias) constitute minor components. Shale dominated fault rocks are restricted to shale-rich protoliths, and fault breccias to break-down of lenses formed near fault jogs. In medium scale faults (1-10m), fault rocks form the dominating facies, whereas the amount of secondary calcite layers decreases due to transformation into breccias. Further, in shale rich carbonates the fault cores consist of composite facies associations. In major faults (10-300 m displacement) fault rock layers and lenses dominate the fault cores. A common observation in large scale faults is a distinct layering of different fault rocks, shale smearing of major shale layers and massive secondary calcite layers along slip surfaces. Fault core heterogeneity in carbonates is ascribed to the distribution of fault facies, such as fault rocks, secondary calcite layers and shale smear. In a broader sense, facies distribution and thickness are controlled by displacement, protolith and tectonic environment. The heterogeneous properties and the varied distribution observed in this study may be valuable in forecasting fault seal characteristics of carbonate reservoirs.

  2. A new fault-thermometer based on vitrinite maturation by coseismic frictional heating

    NASA Astrophysics Data System (ADS)

    Kitamura, Manami; Mukoyoshi, Hideki; Hirose, Takehiro

    2014-05-01

    To detect frictional heating effects along faults provides key insight into the dynamics of earthquakes and faulting [e.g., Brodsky et al., 2010]. Evidence of substantial frictional heating along a fault is also a reliable indicator determining whether a fault has slipped at high velocity in the past, which is crucial for assessing earthquake and tsunami hazard. The reflectance (R) measurement of vitrinite, one of the primary components of coals, has been considered a possible thermometer of fault zones, especially in accretionary wedges where vitrinite fragments are common [e.g., Sakaguchi et al., 2011]. Under normal burial conditions, vitrinite reflectance (R) increases b