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Sample records for alhamilla reverse fault

  1. The initiation of orogenic margin reverse faulting

    NASA Astrophysics Data System (ADS)

    Bailey, R. C.

    2002-04-01

    Laboratory values of rock friction coefficients suggest that reverse faulting should be very difficult to initiate by simple horizontal compression of the crust. Values of stresses required by Andersonian faulting may be an order of magnitude higher than those actually present in orogenic margins. A simple stress balance calculation shows that the effect of the excess lithostatic pressure under an elevated orogen, if transmitted laterally through a crustal ductile layer to the orogenic margin, is to provide sufficient hydraulic lift under the orogen flanks to initiate reverse faulting by direct lift, even with rock friction coefficients of order 0.8. The required orogenic elevation above surrounding ``normal'' lithosphere is about one fifth of the thickness of the brittle crust of the orogen. This elevation may be as small as 2 km in tectonically active regions. The mechanism works even in the absence of regional lithospheric compressive stresses.

  2. The structure and tectonic evolution of the Aguilón fold-nappe, Sierra Alhamilla, Betic Cordilleras, SE Spain

    NASA Astrophysics Data System (ADS)

    Platt, J. P.; van den Eeckhout, B.; Janzen, E.; Konert, G.; Simon, O. J.; Weijermars, R.

    Detailed structural work in the Sierra Alhamilla, SE Spain, shows that the Aguilón nappe, comprising Triassic and older metasedimentary rocks, is a fold-nappe. The most prominent set of small-scale folds changes from dominantly N-vergent in the upper, right-way-up limb to S-vergent in the greatly thinned lower limb. The nappe closes to the north, and must have been emplaced in this direction. Nappe formation was accompanied by small-scale folding and extensive solution-transfer producing a pronounced differentiated crenulation cleavage. These structures overprint an earlier set of folds and cleavage, and are overprinted in turn by late N-vergent structures. The lower limb of the nappe was thinned and disrupted during continued nappe transport. Pre-Triassic schist in the core of the nappe was affected by medium-grade metamorphism of probable post-Triassic age. The contact with low-grade Permo-Triassic sediments above and below the schist coincides with a distinct change in metamorphic grade. This contact may be a post-metamorphic extensional fault that is now folded around the nappe, which suggests that nappe formation was preceded by extensional faulting. This is consistent with gravity spreading as the driving process for nappe emplacement.

  3. Late Cenozoic Reverse Faulting in the Fall Zone, Southeastern Virginia.

    PubMed

    Berquist Jr; Bailey

    1999-11-01

    A set of en-echelon reverse faults cut Paleozoic metamorphosed igneous rocks of the Piedmont and overlying late Cenozoic sediments at the Old Hickory Heavy Mineral Deposit in the Fall Zone of southeastern Virginia. Diorite of the eastern Slate Belt was faulted over nearshore to shore-face deposits of the Pliocene Yorktown Formation. These NW-SE-striking faults experienced oblique dip-slip movement with a maximum displacement of up to 6 m on individual faults. Faults tip out along strike and are overlain by distinct cobble beds, suggesting that sediment deposition and faulting were contemporaneous. Deformation at Old Hickory may have been formed by reactivation of existing Paleozoic structures under a regionally extensive compressional stress field parallel to the modern one. PMID:10517887

  4. Preliminary observations on Quaternary reverse faulting along the southern front of the Northern Range of Trinidad

    SciTech Connect

    Beltran, C. , Caracus )

    1993-02-01

    Several geomorphological evidences of Quaternary reverse faulting are observed along the southern front of the Northern Range in Trinidad between Port-of-Spain and Matura Point. Such a mountain front is associated to a reverse fault system showing an imbricated pattern southward. In the north, the system is limited by a structural feature showing an important vertical component. Southward this system progressively changes to low angle faults. This geometry is corroborated by seismic profiling in the continent shelf. The active faulting evidences consist in lateral drainage offsets, fault trenches, sag-ponds, triangular facets, and saddles. Some quaternary terraces show fault scarps and tilting. We postulate that these reverse fault systems as Arima Fault instead of El Pilar fault as it is not actually connected to the San Sebestian-El Pilar right-lateral slip system, due to the southward prolongation of the southern limit of the Caribbean Plate through the fault system of Los Bajos-El Soldado.

  5. Systematic Underestimation of Earthquake Magnitudes from Large Intracontinental Reverse Faults: Historical Ruptures Break Across Segment Boundaries

    NASA Technical Reports Server (NTRS)

    Rubin, C. M.

    1996-01-01

    Because most large-magnitude earthquakes along reverse faults have such irregular and complicated rupture patterns, reverse-fault segments defined on the basis of geometry alone may not be very useful for estimating sizes of future seismic sources. Most modern large ruptures of historical earthquakes generated by intracontinental reverse faults have involved geometrically complex rupture patterns. Ruptures across surficial discontinuities and complexities such as stepovers and cross-faults are common. Specifically, segment boundaries defined on the basis of discontinuities in surficial fault traces, pronounced changes in the geomorphology along strike, or the intersection of active faults commonly have not proven to be major impediments to rupture. Assuming that the seismic rupture will initiate and terminate at adjacent major geometric irregularities will commonly lead to underestimation of magnitudes of future large earthquakes.

  6. Low-frequency tremors associated with reverse faults in a shallow accretionary prism

    NASA Astrophysics Data System (ADS)

    Obana, Koichiro; Kodaira, Shuichi

    2009-09-01

    The shallow part of a seismogenic subduction zone is thought to play an important role in tsunami genesis during large interplate thrust earthquakes. Near the updip portion of the seismogenic zone along the Nankai trough, splay faults, which are major active reverse faults in the accretionary prism, likely rupture during large interplate earthquakes such as the 1944 Mw 8.2 Tonankai earthquake off Kii Peninsula. We observed low-frequency tremors associated with reverse faults in a shallow accretionary prism off Kii Peninsula at close range by using ocean bottom seismographs. The tremors were characterized by a dominant frequency range of 2-8 Hz and a lack of energy in the frequency range above 10 Hz. Their duration ranged from tens of seconds to a few minutes. Their source locations lay in three clusters on the landward slope of the Nankai trough. Activity in each cluster continued for from one day to two weeks. Many of the low-frequency tremors were located near the shallowest part of a major splay fault. The episodic activity of low-frequency tremors and of previously reported very-low-frequency earthquakes, which indicate reverse faulting in the shallow accretionary prism, suggests that the reverse faults in the accretionary prism are conditionally stable faults that can become unstable under sufficiently strong dynamic loading, such as that caused by a large earthquake. Such reverse faults, as typified by a splay fault, can rupture during large interplate earthquakes and generate large tsunamis.

  7. Frictional controls on high-angle reverse faulting during compressional basin inversion

    NASA Astrophysics Data System (ADS)

    Smith, S. A. F.; Alder, S.; Tesei, T.; Collettini, C.

    2015-12-01

    Large normal faults are often reactivated as high-angle reverse faults during compressional basin inversion. Prevailing models to explain steep reverse slip call upon significant fluid overpressure. Though such models are consistent with some seismological data and field observations from incipient (low-displacement) reverse faults, they remain largely untested in the case of basin-scale faults. We present field and experimental data from the >200 km long Moonlight Fault Zone in New Zealand, an Oligocene basin-bounding normal fault that reactivated in the Miocene as a high-angle reverse fault (present dip angle 65°-75°). Excellent exposures of the fault zone exhumed from c. 4-8 km depth are found in creek sections along the entire strike length. Wall rocks are mainly quartz-albite-muscovite-chlorite schists with a strong foliation that is everywhere sub-parallel to the Moonlight Fault (i.e. dip angle 65°-75°). Although the overall structure of the fault zone changes significantly along strike in response to wall rock composition, the <5 metre thick fault core everywhere contains interconnected layers of foliated cataclasite rich in authigenically-grown chlorite and muscovite/illite. Microstructural evidence suggests deformation in the fault core by a combination of cataclasis, frictional slip along phyllosilicate seams and dissolution-precipitation. Single-direct and double-direct friction experiments were performed with the BRAVA apparatus (INGV, Rome) on saturated wafers (e.g. with intact foliation) of foliated cataclasite at normal stresses up to 75 MPa. The foliated cataclasites have a friction coefficient of <0.25 and negligible frictional healing. In combination with dissolution-precipitation mechanisms, a friction coefficient of <0.25 can account for slip on high-angle reverse faults if accompanied by only moderately high fluid pressures. Our results indicate that friction may be equally as important as fluid pressure during compressional basin inversion.

  8. Late Quaternary faulting on the Manas and Hutubi reverse faults in the northern foreland basin of Tian Shan, China

    NASA Astrophysics Data System (ADS)

    Gong, Zhijun; Li, Sheng-Hua; Li, Bo

    2015-08-01

    The Tian Shan Range lies in the actively deforming part of the India-Asia collision zone. In the northern foreland basin of Tian Shan, the strata were intensively deformed by Cenozoic folding and faulting. Slip rate studies along these faults are important for understanding the dynamics of crustal deformation and evaluating the seismic hazards in the region. Two reverse faults (the Manas and Hutubi faults) in the northern foreland basin were investigated. Due to past faulting events along these faults, the terrace treads along the Manas River were ruptured, forming fault scarps several meters in height. Loess deposits were trapped and preserved at the surface ruptures along these scarps. The thickness of the trapped loess is dependent on the size of the ruptures. The minimum and maximum ages of these scarps are constrained by dating the loess preserved at the surface ruptures and the terrace treads, respectively, using the quartz optically stimulated luminescence (OSL) dating technique. Our dating results suggest that the loess trapped at the ruptures was deposited from the early to mid-Holocene at the Hutubi Fault, and from the mid- to late-Holocene at the Manas Fault. The vertical displacements of the faults were evaluated by measuring the topographic profiles across the investigated fault scarps using the differential global position system (DGPS). Our results suggest that, during the late Quaternary in the studied region, the vertical slip rates of the Manas Fault were between ˜ 0.74 mm /yr and ˜ 1.6 mm /yr, while the Hutubi Fault had a much lower vertical slip rate between ˜ 0.34 mm /yr and ˜ 0.40 mm /yr. The tectonic implications of our results are discussed.

  9. The role of thin, mechanical discontinuities on the propagation of reverse faults: insights from analogue models

    NASA Astrophysics Data System (ADS)

    Bonanno, Emanuele; Bonini, Lorenzo; Basili, Roberto; Toscani, Giovanni; Seno, Silvio

    2016-04-01

    Fault-related folding kinematic models are widely used to explain accommodation of crustal shortening. These models, however, include simplifications, such as the assumption of constant growth rate of faults. This value sometimes is not constant in isotropic materials, and even more variable if one considers naturally anisotropic geological systems. , This means that these simplifications could lead to incorrect interpretations of the reality. In this study, we use analogue models to evaluate how thin, mechanical discontinuities, such as beddings or thin weak layers, influence the propagation of reverse faults and related folds. The experiments are performed with two different settings to simulate initially-blind master faults dipping at 30° and 45°. The 30° dip represents one of the Andersonian conjugate fault, and 45° dip is very frequent in positive reactivation of normal faults. The experimental apparatus consists of a clay layer placed above two plates: one plate, the footwall, is fixed; the other one, the hanging wall, is mobile. Motor-controlled sliding of the hanging wall plate along an inclined plane reproduces the reverse fault movement. We run thirty-six experiments: eighteen with dip of 30° and eighteen with dip of 45°. For each dip-angle setting, we initially run isotropic experiments that serve as a reference. Then, we run the other experiments with one or two discontinuities (horizontal precuts performed into the clay layer). We monitored the experiments collecting side photographs every 1.0 mm of displacement of the master fault. These images have been analyzed through PIVlab software, a tool based on the Digital Image Correlation method. With the "displacement field analysis" (one of the PIVlab tools) we evaluated, the variation of the trishear zone shape and how the master-fault tip and newly-formed faults propagate into the clay medium. With the "strain distribution analysis", we observed the amount of the on-fault and off-fault deformation

  10. High-angle reverse faults, fluid-pressure cycling, and mesothermal gold-quartz deposits

    NASA Astrophysics Data System (ADS)

    Sibson, Richard H.; Robert, Francois; Poulsen, K. Howard

    1988-06-01

    Many mesothermal gold-quartz deposits are localized along high-angle reverse or reverse-oblique shear zones within greenstone belt terrains. Characteristically, these fault-hosted vein deposits exhibit a mixed "brittle-ductile" style of deformation (discrete shears and vein fractures as well as a schistose shear-zone fabric) developed under greenschist facies metamorphic conditions. Many of the vein systems are of considerable vertical extent (>2 km); they include steeply dipping fault veins (lenticular veins subparallel to the shear-zone schistosity) and, in some cases, associated flats (subhorizontal extensional veins). Textures of both vein sets record histories of incremental deposition. We infer that the vein sets developed near the roofs of active metamorphic/magmatic systems and represent the roots of brittle, high-angle reverse fault systems extending upward through the seismogenic regime. Friction theory and field relations suggest that the high-angle reverse faults acted as valves, promoting cyclic fluctuations in fluid pressure from supralithostatic to hydrostatic values. Because of their unfavorable orientation in the prevailing stress field, reactivation of the faults could only occur when fluid pressure exceeded the lithostatic load. Seismogenic fault failure then created fracture permeability within the rupture zone, allowing sudden draining of the geopressured reservoir at depth. Incremental opening of flats is attributed to the prefailure stage of supralithostatic fluid pressures; deposition within fault veins is attributed to the immediate postfailure discharge phase. Hydrothermal self-sealing leads to reaccumulation of fluid pressure and a repetition of the cycle. Mutual crosscutting relations between the two vein sets are a natural consequence of the cyclicity of the process. Abrupt fluid-pressure fluctuations from this fault-valve behavior of reverse faults seem likely to be integral to the mineralizing process at this

  11. Evidence of predominatly reverse-slip on Billefjorden fault zone, northern Dickensonland, Spitsbergen

    SciTech Connect

    Lamar, D.L.; Reed, W.E.; Douglass, D.N.

    1985-01-01

    The Billefjorden fault zone is a 0.5 to 1.0 km wide zone of parallel and branching faults trending N4/sup 0/W. The Balliolbreen fault, the principal strand, has reverse separation and displaces Hecla Hoek metamorphic rocks on the east against Devonian Old Red Sandstone on the west. Large displacement is not required to explain the absence of Old Red Sandstone east of the fault because the Old Red Sandstone thins rapidly to the east. Prior to being overlain by Carboniferous rocks, the Balliolbreen fault dipped about 60/sup 0/ and other fault strands dip 39/sup 0/ to 68/sup 0/. Folds in Old red Sandstone are tight and overturned adjacent to the fault zone and become open and upright to the west. Fold axes and thrusts with separations not exceeding a few hundred meters have sinuous patterns and trends ranging from N40/sup 0/E to N45/sup 0/W; they do not intersect the fault zone with consistent trend characteristic of strike-slip faults. The gentle dip of individual fault strands and the pattern of folds and thrusts suggest east-west compression and predominatly reverse-slip. Eight samples of Old Red Sandstone have yielded a paleomagnetic pole of 32/sup 0/N, 160/sup 0/E, similar (within errors) to others determined for Spitsbergen. Comparison with paleopoles in upper Silurian and lower Devonian rocks in Norway indicates either no movement or right-slip of Spitsbergen with respect to Norway. These results do not support earlier suggestions of post-Old Red Sandstone left-slip of 200 to 1000 km on the Billefjorden fault zone.

  12. Imaging Faults with Reverse-Time Migration for Geothermal Exploration at Jemez Pueblo in New Mexico

    SciTech Connect

    Huang, Lianjie; Albrecht, Michael; Kaufman, Greg; Kelley, Shari; Rehfeldt, Kenneth; Zhang, Zhifu

    2011-01-01

    The fault zones at Jemez Pueblo may dominate the flow paths of hot water, or confine the boundaries of the geothermal reservoir. Therefore, it is crucial to image the geometry of these fault zones for geothermal exploration in the area. We use reverse-time migration with a separation imaging condition to image the faults at Jemez Pueblo. A finite-difference full-wave equation method with a perfectly-matching-layer absorbing boundary condition is used for backward propagation of seismic reflection data from receivers and forward propagation of wavefields from sources. In the imaging region, the wavefields are separated into the upgoing and downgoing waves, and leftgoing and rightgoing waves. The upgoing and downgoing waves are used to obtain the downward-looking image, and the leftgoing and rightgoing waves are used to form the left-looking image and right-looking image from sources. The left-looking and right-looking images are normally weaker than the downward-looking image because the reflections from the fault zones are much weaker than those from sedimentary layers, but these migration results contain the images of the faults. We apply our reverse-time migration with a wavefield separation imaging condition to seismic data acquired at Jemez Pueblo, and our preliminary results reveal many faults in the area.

  13. Reverse Computation for Rollback-based Fault Tolerance in Large Parallel Systems

    SciTech Connect

    Perumalla, Kalyan S; Park, Alfred J

    2013-01-01

    Reverse computation is presented here as an important future direction in addressing the challenge of fault tolerant execution on very large cluster platforms for parallel computing. As the scale of parallel jobs increases, traditional checkpointing approaches suffer scalability problems ranging from computational slowdowns to high congestion at the persistent stores for checkpoints. Reverse computation can overcome such problems and is also better suited for parallel computing on newer architectures with smaller, cheaper or energy-efficient memories and file systems. Initial evidence for the feasibility of reverse computation in large systems is presented with detailed performance data from a particle simulation scaling to 65,536 processor cores and 950 accelerators (GPUs). Reverse computation is observed to deliver very large gains relative to checkpointing schemes when nodes rely on their host processors/memory to tolerate faults at their accelerators. A comparison between reverse computation and checkpointing with measurements such as cache miss ratios, TLB misses and memory usage indicates that reverse computation is hard to ignore as a future alternative to be pursued in emerging architectures.

  14. Do buried-rupture earthquakes trigger less landslides than surface-rupture earthquakes for reverse faults?

    NASA Astrophysics Data System (ADS)

    Xu, Chong

    2014-07-01

    Gorum et al. (2013, Geomorphology 184, 127-138) carried out a study on inventory compilation and statistical analyses of landslides triggered by the 2010 Mw 7.0 Haiti earthquake. They revealed that spatial distribution patterns of these landslides were mainly controlled by complex rupture mechanism and topography. They also suggested that blind-rupture earthquakes trigger fewer landslides than surface-rupture earthquakes on thrust reverse faults. Although a few lines of evidence indicate that buried-rupture earthquakes might trigger fewer landslides than surface-rupture earthquakes on reverse faults, more careful comparisons and analyses indicate that it is not always true. Instead, some cases show that a buried-rupture earthquake can trigger a larger quantity of landslides that are distributed in a larger area, whereas surface-rupture earthquakes can trigger larger but a fewer landslides distributed in a smaller area.

  15. Wrinkle ridges, reverse faulting, and the depth penetration of lithospheric stress in lunae planum, Mars

    NASA Technical Reports Server (NTRS)

    Zuber, M. T.

    1993-01-01

    Tectonic features on a planetary surface are commonly used as constraints on models to determine the state of stress at the time the features formed. Quantitative global stress models applied to understand the formation of the Tharsis province on Mars constrained by observed tectonics have calculated stresses at the surface of a thin elastic shell and have neglected the role of vertical structure in influencing the predicted pattern of surface deformation. Wrinkle ridges in the Lunae Planum region of Mars form a conentric pattern of regularly spaced features in the eastern and southeastern part of Tharsis; they are formed due to compressional stresses related to the response of the Martian lithosphere to the Tharsis bulge. As observed in the exposures of valley walls in areas such as the Kasei Valles, the surface plains unit is underlain by an unconsolidated impact-generated megaregolith that grades with depth into structurally competent lithospheric basement. The ridges have alternatively been hypothesized to reflect deformation restricted to the surface plains unit ('thin skinned deformation') and deformation that includes the surface unit, megaregolith and basement lithosphere ('thick skinned deformation'). We have adopted a finite element approach to quantify the nature of deformation associated with the development of wrinkle ridges in a vertically stratified elastic lithosphere. We used the program TECTON, which contains a slippery node capability that allowed us to explicitly take into account the presence of reverse faults believed to be associated with the ridges. In this study we focused on the strain field in the vicinity of a single ridge when slip occurs along the fault. We considered two initial model geometries. In the first, the reverse fault was assumed to be in the surface plains unit, and in the second the initial fault was located in lithospheric basement, immediately beneath the weak megaregolith. We are interested in the conditions underwhich

  16. Seismicity Following Deep Reverse-Faulting in the Indian Plate: Implications for Gujarat

    NASA Astrophysics Data System (ADS)

    Bilham, R.; Wallace, K.; Bendick, R.

    2001-12-01

    The catastrophic 1819 Allah Bund M=7.7, 1897 Shillong M=8.1, and 2001 Bhuj M=7.6 earthquakes all occurred on buried steep-dipping reverse faults. Each resulted in shortening of the Indian plate in an approximately NW direction, and each consequently loaded the contiguous plate to the east and west. These locally increased stresses are significant compared to the cumulative geodetically-inferred intraplate loading in the past century. Following the 19th century events these adjacent regions subsequently experienced damaging earthquakes. The Bhuj event itself may have been triggered by, or advanced in time by, stress changes resulting from the 1819 earthquake. There is thus some concern that future seismicity east and west of the Bhuj rupture zone will be stimulated by the recent Bhuj event. Stress changes above buried reverse-faulting is compressive and significant. Data for the early events are too poor to assess depths, however, aftershock activity in the uppermost 8 km following the Bhuj earthquake is remarkably low. One explanation for the absence of shallow aftershock activity is that the Anjar 1956 event may have already released near-surface stress, incrementing the region of the 2001 rupture towards failure. Significant earthquakes (67) may now occur 100-200 km east or west of the epicentral region.

  17. Focusing of relative plate motion at a continental transform fault: Cenozoic dextral displacement >700 km on New Zealand's Alpine Fault, reversing >225 km of Late Cretaceous sinistral motion

    NASA Astrophysics Data System (ADS)

    Lamb, Simon; Mortimer, Nick; Smith, Euan; Turner, Gillian

    2016-03-01

    The widely accepted ˜450 km Cenozoic dextral strike-slip displacement on New Zealand's Alpine Fault is large for continental strike-slip faults, but it is still less than 60% of the Cenozoic relative plate motion between the Australian and Pacific plates through Zealandia, with the remaining motion assumed to be taken up by rotation and displacement on other faults in a zone up to 300 km wide. We show here that the 450 km total displacement across the Alpine Fault is an artifact of assumptions about the geometry of New Zealand's basement terranes in the Eocene, and the actual Cenozoic dextral displacement across the active trace is greater than 665 km, with more than 700 km (and <785 km since 25 Ma) occurring in a narrow zone less than 10 km wide. This way, the Alpine Fault has accommodated almost all (>94%) of the relative plate motion in the last 25 Ma at an average rate in excess of 28 mm/yr. It reverses more than 225 km (and <300 km) of sinistral shear through Zealandia in the Late Cretaceous, when Zealandia lay on the margin of Gondwana, providing a direct constraint on the kinematics of extension between East and West Antarctica at this time.

  18. High-angle reverse faulting in northern New Brunswick, Canada, and its implications for fluid pressure levels

    NASA Astrophysics Data System (ADS)

    Sibson, Richard H.

    The 1982 Miramichi earthquake sequence in northern New Brunswick included four shocks in the magnitude range, 5.7 > m, > 5.0, and extensive aftershock activity. Rupturing occurred within granitic terrain on a pair of NNE—SSW-striking, opposite-facing, high-angle reverse faults which converge at the mainshock focal depth of ≈7 km. It seems probable that the earthquake sequence involved the reactivation under horizontal compression of an existing set of steep normal faults, perhaps derived from Mesozoic rifting of the Atlantic continental margin. The symmetry of the V-shaped profile of faults in WNW—ESE section suggests that the maximum principal compressive stress (σ 1) during reactivation was subhorizontal and the least principal stress (σ 3) was subvertical, so that the reactivation angle between σ 1 and the faults corresponded to the 50-65° dip of the faults. Stress analysis of the conditions for frictional reactivation of existing cohesionless faults shows that pore-fluid pressures approaching or exceeding lithostatic values are required for reshear at such high reactivation angles, with the implication that the earthquake sequence was triggered by locally elevated fluid pressure. While the source and composition of the inferred high pressure fluids are uncertain, a mixed H 2O—CO 2 fluid of mantle origin seems most likely.

  19. Forward and Reverse Modeling Compressive Deformation in a 3D Geologic Model along the Central San Andreas Fault Zone

    NASA Astrophysics Data System (ADS)

    Roberts, M. A.; Graymer, R. W.; McPhee, D.

    2015-12-01

    During the late Miocene, a small change in the relative motion of the Pacific plate resulted in compressive as well as translational deformation along the central San Andreas Fault (SAF), creating thrust faults and folds throughout this region of California. We constructed a 3D model of an upper crustal volume between Pinnacles National Park and Gold Hill by assembling geologic map data and cross sections, geophysical data, and petroleum well logs in MoveTm, software which has the ability to forward and reverse model movement along faults and folds. For this study, we chose a blind thrust fault west of the SAF near Parkfield to compare deformation produced by MoveTm's forward modeling algorithm with that observed. We chose various synclines east of the SAF to explore the software's ability to unfold (reverse model) units. For the initial round of modeling, strike-slip movement has been omitted as the fault algorithm was designed primarily for extensional or compressional environments. Preliminary forward modeling of originally undeformed strata along the blind thrust produced geometries similar to those in the present-day 3D geologic model. The modeled amount of folding produced in hanging wall strata was less severe, suggesting these units were slightly folded before displacement. Based on these results, the algorithm shows potential in predicting deformation related to blind thrusts. Contraction in the region varies with fold axis location and orientation. MoveTm's unfolding algorithm can allow researchers to measure the amount of contraction a fold represents, and compare that amount across the modeled area as a way of observing regional stress patterns. The unfolding algorithm also allows for passive deformation of strata unconformably underlying the fold; one example reveals a steeper orientation of Cretaceous units prior to late Miocene deformation. Such modeling capabilities can allow for a better understanding of the structural history of the region.

  20. Buttressing and reverse reactivation of a normal fault in the Jurassic rocks of the Asturian Basin, NW Iberian Peninsula

    NASA Astrophysics Data System (ADS)

    Uzkeda, H.; Bulnes, M.; Poblet, J.; García-Ramos, J. C.; Piñuela, L.

    2013-06-01

    A detailed structural analysis was carried out on the Jurassic rocks cropping out along the cliffs of La Conejera Inlet (Asturias, Spain). It includes a geological map and a distortion-free cross-section constructed via photogrammetric methods. La Conejera Inlet is located within the Asturian Basin, a Permian-Mesozoic extensional basin partially formed during the opening of the Bay of Biscay. It suffered selective basin inversion during a Cenozoic contraction responsible for the Pyrenees and its western prolongation along the north margin of the Iberian Peninsula. The study of the structures (folds, faults, joints and veins) of the hangingwall of two normal faults with opposite dip senses reveals that it underwent a later compressional stage in which one fault block acted as a buttress. The contractional deformation in the hangingwall, interpreted as a deformed rollover anticline with an associated antithetic fault, diminishes on moving away from one of the main faults. The positive inversion tectonics produced not only a buttressing effect, but it also involved a certain amount of reverse reactivation of one of the main faults that still preserves a normal displacement. The original normal motion would have taken place during the Middle?-Late Jurassic, related to an embryonic stage of the opening of the Bay of Biscay. The later contractional stage would have been caused by the Cenozoic Alpine shortening. The good outcrop quality allows a relative chronology for the observed structures to be established. Employing all the available information we tried to reconstruct the structure at depth and predict the detachment depth, and to estimate the amounts of extension (the present-day value and that before the compression) and compression.

  1. Tectonic reversal of the western Doruneh Fault System: Implications for Central Asian tectonics

    NASA Astrophysics Data System (ADS)

    Javadi, Hamid Reza; Esterabi Ashtiani, Marzieh; Guest, Bernard; Yassaghi, Ali; Ghassemi, Mohammad Reza; Shahpasandzadeh, Majid; Naeimi, Amir

    2015-10-01

    The left-lateral Doruneh Fault System (DFS) bounds the north margin of the Central Iranian microplate and has played an important role in the structural evolution of the Turkish-Iranian plateau. The western termination of the DFS is a sinistral synthetic branch fault array that shows clear kinematic evidence of having undergone recent slip sense inversion from a dextral array to a sinistral array in the latest Neogene or earliest Quaternary. Similarly, kinematic evidence from the Anarak Metamorphic complex suggests that this complex initially developed at a transpressive left-stepping termination of the DFS and that it was inverted in the latest Neogene to a transtensional fault termination. The recognition that the DFS and other faults in NE Iran were inverted from dextral to sinistral strike slip in the latest Neogene and the likely connection between the DFS and the Herat Fault of Afghanistan suggests that prior to the latest Miocene, all of the north Iranian and northern Afghan ranges were part of a distributed dextral fault network that extended from the west Himalayan syntaxes to the western Alborz. Also, the recognition that regional slip sense inversion occurred across northern and northeastern Iran after the latest Miocene invalidates tectonic models that extrapolate Pleistocene to recent fault slip kinematics and rates back beyond this time.

  2. Involvement of Overpressured Fluids in the Nucleation of High-Angle Reverse Ruptures: Evidence from Fault-Hosted Hydrothermal Vein Systems

    NASA Astrophysics Data System (ADS)

    Sibson, R. H.

    2007-12-01

    Dips of near-pure reverse-slip M>5.5 ruptures are bimodally distributed with a dominant peak at δ = 30±5°, a subordinate peak at δ = 50±5°, and no ruptures with δ > 60°. Assuming horizontal trajectories for maximum compressive stress (σ1), the dominant peak corresponds to optimally oriented faults with Byerlee friction coefficients (μs = 0.6) for which frictional lock-up is expected at δ = 60°. In recent years, several compressional inversion earthquakes in the upper crust of Honshu, Japan (e.g. the 2003 Mw6.5 Northern Miyagi, the 2004 Mw6.6 Mid-Niigata Prefecture, and the 2007 Mw6.7 Noto-Hanto sequences) have involved high-angle reverse-slip with dips of 50-60° on inherited normal faults along the margins of Miocene extensional basins. Rupturing during these earthquakes thus took place on faults that were poorly oriented for frictional reactivation and close to lock-up. Frictional mechanics suggests that reshear of the steep reverse faults (in preference to the formation of new favorably oriented thrusts within intact crust) is allowable only under near- lithostatic fluid pressures with Pf approaching σ3, and that reshear of severely misoriented faults (δ > c.60°) requires Pf > σ3 (the hydrofracture condition). Notably, the 2004 Mid-Niigata sequence involved a criss-crossing network of high-angle and low-angle reverse ruptures, suggesting competition between reshear of steep inherited faults and the formation of more favorably oriented thrusts. A range of geophysical evidence, including local bright S-wave reflectors, indicates strong fluid overpressuring in the focal regions of these earthquakes. Mesozonal Au-quartz vein systems hosted in reverse faults exhumed from depths corresponding to the lower half of the seismogenic zone (P ~ 2-4 kbar; T ~ 250-400°C) occur throughout the geological record and provide additional evidence for the involvement of strongly overpressured fluids in reverse fault rupturing. Incrementally deposited fault

  3. Tension crack characteristics of surface ruptures of 2 strong earthquakes recently occurred along reverse faults in China

    NASA Astrophysics Data System (ADS)

    Liu, Mingjun; Dai, Aopeng; Zhang, Feng

    2014-05-01

    Field investigations show that there are some tension cracks in the surface ruptures of 2 strong earthquakes recently occurred along reverse faults with strike-slip component in China. Yushu Ms7.1 earthquake occurred on April 14, 2010 in Qinghai, China produced a ~65 km long co-seismic surface rupture with a strike of 310°, which is distributed along Ganzi-Yushu fault that is a reverse fault with strike-slip component in the Qinghai—Tibetan Plateau. The surface rupture of Yushu Ms7.1 earthqake consists of shear, transtensional cracks, transpressional cracks, tension cracks and mole tracks. Some tension cracks occur on the top of small uplifts and the cracking course is from surface to undergound for some tension cracks are shallow. The small uplifts are actually anticlines produced by a regional and deep compressional stress field, but there is a local tensional stress field on the top of the anticlines. Lushan Ms7.0 earthquake on 20 April 20, 2013 in Sichuan, China occurred on the southern segment of the Longmenshan fault zone with a NE strike which is also a reverse fault zone with strike-slip component, but only a co-seismic surface rupture 80m long with a NW strike was found without any NE-striking surface rupture found. The surface rupture shows the form of tension cracks on a top of a small uplift. There are two sets of fresh striation on the surface rupture plane, the striation with larger plunge angles usually only remains above the range 10-20cm below the ground surface, which is covered by the striation with smaller plunging angles. The comprehensive analysis shows that the surface rupture during the Ms7.0 Lushan earthquake at first experienced thrusting, then sinistral strike-slip, and tension cracking at last. In general, some tension cracks of the surface ruptures from Yushu Ms7.1 earthquake on April 14, 2010 and Lushan Ms7.0 earthquake on 20 April 2013 may be produced by the local tensional stress field, but they also reflect the regional and deep

  4. Reverse Faulting as a Crucial Mechanism for Magma Ascent in Compressional Volcanic Arcs: Field Examples from the Central Andes

    NASA Astrophysics Data System (ADS)

    Aron, F. A.; Gonzalez, G.; Cembrano, J. M.; Veloso, E. E.

    2010-12-01

    The nature of crustal deformation in active arcs and the feedback mechanisms between tectonics and magma transport constitute fundamental problems in the understanding of volcanic systems. Additionally, for geothermal energy exploration, a better understanding of how crustal architecture and stress field controls fluid ascent and heat transfer from deep levels to the surface is crucial. The Central Andes volcanic belt is an excellent, modern example of such systems but, the scarcity of good outcrops has limited our ability to define the relations between structure and volcanism. In the Salar de Atacama Basin of northern Chile, there are good exposures of folded and faulted Neogene units (continental sediments, volcanic rocks and ignimbrites) and reverse faults spatially and temporally related to volcanic edifices. The subsurface of the study area has been interpreted by previous authors as a thin-skinned, 6-8 km-deep, east-vergent compressional belt. We carried out structural mapping, Digital Elevation Models (DEMs) analyses, strain tensor analyses and fault-related fold kinematic modelling to assess the causal relationship between compressional deformation and magmatism in this region. Field observations indicate that the structures deformed progressively Oligocene-Miocene continental sedimentary units, the upper sedimentary infill of the Salar de Atacama basin (Pliocene-Present), and Pliocene-Pleistocene Ignimbrites. The topographic expression of the compressional belt corresponds to a set of subparallel, asymmetric, fault-related-folds, which can be seen in the field as prominent NS-trending ridges with heights ranging between 50 and 400 m. Furthermore, we found evidence of a ~100 km-long structure along the active magmatic arc, so-called Miscanti Fault. This fault represents the easternmost expression of the above mentioned compressional belt. Pleistocene-Holocene monogenetic cones and strato-volcanoes are located either at the hinge zone of fault

  5. Slip reversals on active normal faults related to the inflation and deflation of magma chambers: Numerical modeling with application to the Yellowstone-Teton region

    NASA Astrophysics Data System (ADS)

    Hampel, Andrea; Hetzel, Ralf

    2008-04-01

    Earthquakes and coseismic slip on faults are the common response of Earth's crust to plate-tectonic forces. Here we demonstrate, using three-dimensional numerical experiments, that pulses of magmatic activity may alter the slip behavior of nearby tectonic faults by causing unusual aseismic creep and even reversals in the sense of slip. We apply our results to the Teton normal fault, Wyoming, which experienced hitherto unexplained episodes of reverse and normal creep between 1988 and 2001, to show that its anomalous behavior can be explained by inflation and deflation of two magma chambers beneath the Yellowstone caldera. Our findings imply a strong coupling between magmatism and tectonic faulting, which requires coordinated monitoring of both processes to improve our understanding of the resulting spatial and temporal strain pattern.

  6. Upper Plate Reverse Fault Reactivation and the March-April 2014 Pisagua Earthquake Sequence in Northern Chile

    NASA Astrophysics Data System (ADS)

    Gonzalez, G.; Salazar, P.; Loveless, J. P.; Allmendinger, R. W.; Aron, F.; Shrivastava, M. N.

    2014-12-01

    The March 16-April 3, 2014 Pisagua earthquake sequence ruptured the middle part of the southern Peru-northern Chile seismic gap in the curved segment of the Andean subduction zone. The sequence began on March 16, with an Mw 6.7 earthquake that struck near the central section of the gap. A few hours after this initial event, intense seismic activity began and persisted for two weeks, showing a progressive northward migration towards the position of the main Mw 8.1 shock of this sequence. Two days after the main shock, a second large Mw 7.7 earthquake ruptured at the southern part of the area.. We relocated 336 events of this sequence by using data from a local network (Integrated Plate boundary Observatory Chile, IPOC). From NonLinLoc, HypoDD and waveform analysis, we relocated the Mw 6.7 in the upper plate at 12-14 km depth. Coulomb stress analysis shows that this initial event was able to trigger seismicity on the megathrust leading finally to the Mw 8.1. The initial Mw 6.7 event and some foreshocks have an unusual focal mechanism in comparison to the strike of the subduction interface. The nodal planes are rotated anticlockwise with respect to the slab surface strike. The shortening axes of the upper plate events plunges ~30° towards 220°, highly oblique to P axes of the foreshocks and main shock on the plate interface. On-shore regional structures are dominated by trench orthogonal reverse faults indicating the prevalence of long-term trench parallel shortening in the area. Upper plate micro seismic events, captured before this sequence, have focal mechanisms with E-W striking nodal planes and trench parallel shortening. Our analysis supports the idea of a causative relationship between upper plate long-term structures and the reactivation of the subduction megathrust. The concave seaward geometry of the margin and the trench orthogonal striking reverse faults observed in northern Chile are also common in the Cascadia margin, therefore we propose that both

  7. Seismotectonics and rupture process of the MW 7.1 2011 Van reverse-faulting earthquake, Eastern Turkey, and implications for hazard in regions of distributed shortening

    NASA Astrophysics Data System (ADS)

    Mackenzie, D.; Elliott, J. R.; Altunel, E.; Walker, R. T.; Kurban, Y. C.; Schwenninger, J.-L.; Parsons, B.

    2016-04-01

    The 23 October 2011 MW 7.1 Van earthquake in eastern Turkey caused ˜600 deaths and caused widespread damage and economic loss. The seismogenic rupture was restricted to 10-25 km in depth, but aseismic surface creep, coincident with outcrop fault exposures, was observed in the hours to months after the earthquake. We combine observations from radar interferometry, seismology, geomorphology and Quaternary dating to investigate the geological slip rate and seismotectonic context of the Van earthquake, and assess the implications for continuing seismic hazard in the region. Transient post-seismic slip on the upper Van fault started immediately following the earthquake, and decayed over a period of weeks; it may not fully account for our long-term surface slip-rate estimate of ≥0.5 mm/yr. Post-seismic slip on the Bostaniçi splay fault initiated several days to weeks after the mainshock, and we infer that it may have followed the MW 5.9 aftershock on the 9th November. The Van earthquake shows that up-dip segmentation can be important in arresting seismic ruptures on dip-slip faults. Two large, shallow aftershocks show that the upper 10 km of crust can sustain significant earthquakes, and significant slip is observed to have reached the surface in the late Quaternary, so there may be a continuing seismic hazard from the upper Van Fault and the associated splay. The wavelength of folding in the hanging-wall of the Van fault is dominated by the structure in the upper 10 km of the crust, masking the effect of deeper seismogenic structures. Thus, models of subsurface faulting based solely on surface folding and faulting in regions of reverse faulting may underestimate the full depth extent of seismogenic structures in the region. In measuring the cumulative postseismic offsets to anthropogenic structures, we show that Structure-from-Motion can be rapidly deployed to create snapshots of postseismic displacement. We also demonstrate the utility of declassified Corona

  8. Seismotectonics and rupture process of the MW 7.1 2011 Van reverse-faulting earthquake, eastern Turkey, and implications for hazard in regions of distributed shortening

    NASA Astrophysics Data System (ADS)

    Mackenzie, D.; Elliott, J. R.; Altunel, E.; Walker, R. T.; Kurban, Y. C.; Schwenninger, J.-L.; Parsons, B.

    2016-07-01

    The 2011 October 23 MW 7.1 Van earthquake in eastern Turkey caused ˜600 deaths and caused widespread damage and economic loss. The seismogenic rupture was restricted to 10-25 km in depth, but aseismic surface creep, coincident with outcrop fault exposures, was observed in the hours to months after the earthquake. We combine observations from radar interferometry, seismology, geomorphology and Quaternary dating to investigate the geological slip rate and seismotectonic context of the Van earthquake, and assess the implications for continuing seismic hazard in the region. Transient post-seismic slip on the upper Van fault started immediately following the earthquake, and decayed over a period of weeks; it may not fully account for our long-term surface slip-rate estimate of ≥0.5 mm yr-1. Post-seismic slip on the Bostaniçi splay fault initiated several days to weeks after the main shock, and we infer that it may have followed the MW 5.9 aftershock on the 9th November. The Van earthquake shows that updip segmentation can be important in arresting seismic ruptures on dip-slip faults. Two large, shallow aftershocks show that the upper 10 km of crust can sustain significant earthquakes, and significant slip is observed to have reached the surface in the late Quaternary, so there may be a continuing seismic hazard from the upper Van fault and the associated splay. The wavelength of folding in the hanging wall of the Van fault is dominated by the structure in the upper 10 km of the crust, masking the effect of deeper seismogenic structures. Thus, models of subsurface faulting based solely on surface folding and faulting in regions of reverse faulting may underestimate the full depth extent of seismogenic structures in the region. In measuring the cumulative post-seismic offsets to anthropogenic structures, we show that Structure-from-Motion can be rapidly deployed to create snapshots of post-seismic displacement. We also demonstrate the utility of declassified Corona

  9. 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…

  10. Using a modified time-reverse imaging technique to locate low-frequency earthquakes on the San Andreas Fault near Cholame, California

    NASA Astrophysics Data System (ADS)

    Horstmann, Tobias; Harrington, Rebecca M.; Cochran, Elizabeth S.

    2015-11-01

    We present a new method to locate low-frequency earthquakes (LFEs) within tectonic tremor episodes based on time-reverse imaging techniques. The modified time-reverse imaging technique presented here is the first method that locates individual LFEs within tremor episodes within 5 km uncertainty without relying on high-amplitude P-wave arrivals and that produces similar hypocentral locations to methods that locate events by stacking hundreds of LFEs without having to assume event co-location. In contrast to classic time-reverse imaging algorithms, we implement a modification to the method that searches for phase coherence over a short time period rather than identifying the maximum amplitude of a superpositioned wavefield. The method is independent of amplitude and can help constrain event origin time. The method uses individual LFE origin times, but does not rely on a priori information on LFE templates and families. We apply the method to locate 34 individual LFEs within tremor episodes that occur between 2010 and 2011 on the San Andreas Fault, near Cholame, California. Individual LFE location accuracies range from 2.6 to 5 km horizontally and 4.8 km vertically. Other methods that have been able to locate individual LFEs with accuracy of less than 5 km have mainly used large-amplitude events where a P-phase arrival can be identified. The method described here has the potential to locate a larger number of individual low-amplitude events with only the S-phase arrival. Location accuracy is controlled by the velocity model resolution and the wavelength of the dominant energy of the signal. Location results are also dependent on the number of stations used and are negligibly correlated with other factors such as the maximum gap in azimuthal coverage, source-station distance and signal-to-noise ratio.

  11. Using a modified time-reverse imaging technique to locate low-frequency earthquakes on the San Andreas Fault near Cholame, California

    USGS Publications Warehouse

    Horstmann, Tobias; Harrington, Rebecca M.; Cochran, Elizabeth S.

    2015-01-01

    We present a new method to locate low-frequency earthquakes (LFEs) within tectonic tremor episodes based on time-reverse imaging techniques. The modified time-reverse imaging technique presented here is the first method that locates individual LFEs within tremor episodes within 5 km uncertainty without relying on high-amplitude P-wave arrivals and that produces similar hypocentral locations to methods that locate events by stacking hundreds of LFEs without having to assume event co-location. In contrast to classic time-reverse imaging algorithms, we implement a modification to the method that searches for phase coherence over a short time period rather than identifying the maximum amplitude of a superpositioned wavefield. The method is independent of amplitude and can help constrain event origin time. The method uses individual LFE origin times, but does not rely on a priori information on LFE templates and families.We apply the method to locate 34 individual LFEs within tremor episodes that occur between 2010 and 2011 on the San Andreas Fault, near Cholame, California. Individual LFE location accuracies range from 2.6 to 5 km horizontally and 4.8 km vertically. Other methods that have been able to locate individual LFEs with accuracy of less than 5 km have mainly used large-amplitude events where a P-phase arrival can be identified. The method described here has the potential to locate a larger number of individual low-amplitude events with only the S-phase arrival. Location accuracy is controlled by the velocity model resolution and the wavelength of the dominant energy of the signal. Location results are also dependent on the number of stations used and are negligibly correlated with other factors such as the maximum gap in azimuthal coverage, source–station distance and signal-to-noise ratio.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  13. Normal faults, normal friction?

    NASA Astrophysics Data System (ADS)

    Collettini, Cristiano; Sibson, Richard H.

    2001-10-01

    Debate continues as to whether normal faults may be seismically active at very low dips (δ < 30°) in the upper continental crust. An updated compilation of dip estimates (n = 25) has been prepared from focal mechanisms of shallow, intracontinental, normal-slip earthquakes (M > 5.5; slip vector raking 90° ± 30° in the fault plane) where the rupture plane is unambiguously discriminated. The dip distribution for these moderate-to-large normal fault ruptures extends from 65° > δ > 30°, corresponding to a range, 25° < θr < 60°, for the reactivation angle between the fault and inferred vertical σ1. In a comparable data set previously obtained for reverse fault ruptures (n = 33), the active dip distribution is 10° < δ = θr < 60°. For vertical and horizontal σ1 trajectories within extensional and compressional tectonic regimes, respectively, dip-slip reactivation is thus restricted to faults oriented at θr ≤ 60° to inferred σ1. Apparent lockup at θr ≈ 60° in each dip distribution and a dominant 30° ± 5° peak in the reverse fault dip distribution, are both consistent with a friction coefficient μs ≈ 0.6, toward the bottom of Byerlee's experimental range, though localized fluid overpressuring may be needed for reactivation of less favorably oriented faults.

  14. Zipper Faults

    NASA Astrophysics Data System (ADS)

    Platt, J. P.; Passchier, C. W.

    2015-12-01

    Intersecting simultaneously active pairs of faults with different orientations and opposing slip sense ("conjugate faults") present geometrical and kinematic problems. Such faults rarely offset each other, even when they have displacements of many km. A simple solution to the problem is that the two faults merge, either zippering up or unzippering, depending on the relationship between the angle of intersection and the slip senses. A widely recognized example of this is the so-called blind front developed in some thrust belts, where a backthrust branches off a decollement surface at depth. The decollement progressively unzippers, so that its hanging wall becomes the hanging wall of the backthrust, and its footwall becomes the footwall of the active decollement. The opposite situation commonly arises in core complexes, where conjugate low-angle normal faults merge to form a single detachment; in this case the two faults zipper up. Analogous situations may arise for conjugate pairs of strike-slip faults. We present kinematic and geometrical analyses of the Garlock and San Andreas faults in California, the Najd fault system in Saudi Arabia, the North and East Anatolian faults, the Karakoram and Altyn Tagh faults in Tibet, and the Tonale and Guidicarie faults in the southern Alps, all of which appear to have undergone zippering over distances of several tens to hundreds of km. The zippering process may produce complex and significant patterns of strain and rotation in the surrounding rocks, particularly if the angle between the zippered faults is large. A zippering fault may be inactive during active movement on the intersecting faults, or it may have a slip rate that differs from either fault. Intersecting conjugate ductile shear zones behave in the same way on outcrop and micro-scales.

  15. 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.

  16. Hayward Fault, California Interferogram

    NASA Technical Reports Server (NTRS)

    2000-01-01

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

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

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

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

  17. 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

  18. 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

  19. Architecture of small-scale fault zones in the context of the Leinetalgraben Fault System

    NASA Astrophysics Data System (ADS)

    Reyer, Dorothea; Philipp, Sonja L.

    2010-05-01

    Understanding fault zone properties in different geological settings is important to better assess the development and propagation of faults. In addition this allows better evaluation and permeability estimates of potential fault-related geothermal reservoirs. The Leinetalgraben fault system provides an outcrop analogue for many fault zones in the subsurface of the North German Basin. The Leinetalgraben is a N-S-trending graben structure, initiated in the Jurassic, in the south of Lower Saxony and as such part of the North German Basin. The fault system was reactivated and inverted during Alpine compression in the Tertiary. This complex geological situation was further affected by halotectonics. Therefore we can find different types of fault zones, that is normal, reverse, strike-slip an oblique-slip faults, surrounding the major Leinetalgraben boundary faults. Here we present first results of structural geological field studies on the geometry and architecture of fault zones in the Leinetalgraben Fault System in outcrop-scale. We measured the orientations and displacements of 17 m-scale fault zones in limestone (Muschelkalk) outcrops, the thicknesses of their fault cores and damage zones, as well as the fracture densities and geometric parameters of the fracture systems therein. We also analysed the effects of rock heterogeneities, particularly stiffness variations between layers (mechanical layering) on the propagation of natural fractures and fault zones. The analysed fault zones predominantly show similar orientations as the major fault zones they surround. Other faults are conjugate or perpendicular to the major fault zones. The direction of predominant joint strike corresponds to the orientation of the fault zones in the majority of cases. The mechanical layering of the limestone and marlstone stratification obviously has great effects on fracture propagation. Already thin layers (mm- to cm-scale) of low stiffness - here marl - seem to suffice to change the

  20. Quantifying Anderson's fault types

    USGS Publications Warehouse

    Simpson, R.W.

    1997-01-01

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

  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 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

  3. 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.

  4. 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.

  5. Triggered slip on a back reverse fault in the Mw6.8 2013 Lushan, China earthquake revealed by joint inversion of local strong motion accelerograms and geodetic measurements

    NASA Astrophysics Data System (ADS)

    Zhang, Guohong; Hetland, Eric A.; Shan, Xinjian; Vallée, Martin; Liu, Yunhua; Zhang, Yingfeng; Qu, Chunyan

    2016-03-01

    The 2013 Mw6.8 Lushan, China earthquake occurred in the southwestern end of the Longmenshan fault zone. We jointly invert local strong motion data and geodetic measurements of coseismic surface deformation, including GPS and InSAR, to obtain a robust model of the rupture process of the 2013 Lushan earthquake. Our joint inversion best model involves the rupture of two opposing faults during the Lushan earthquake, a main fault and a secondary fault. It is only when the secondary fault is included that both the GPS and InSAR measurements are fit along with the near-field strong motion. Over 75% of the computed moment was released in slip on the main fault segment, a northwest dipping, listric thrust fault, with buried thrust and dextral strike-slip at hypocenter depths, and with only minor slip closer to the surface. The secondary fault mainly involved oblique thrust slip or pure dextral strike-slip at shallower depths, and accounts for just under 24% of the moment released in the Lushan earthquake. Coulomb stress changes of about 0.5 MPa on the secondary fault segment at the time coseismic slip initiated on that fault indicate that slip was likely triggered by the coseismic slip on the main blind thrust fault. Our coseismic slip model is consistent with a sub-horizontal and east-west to southeast-northwest trending most compressive stress. Our inferred coseismic slip model is also consistent with previous GPS derived models of strain accumulation on the Longmenshan fault system.

  6. Microearthquake seismicity at the intersection between the Kazerun fault and the Main Recent Fault (Zagros, Iran)

    NASA Astrophysics Data System (ADS)

    Yamini-Fard, Farzam; Hatzfeld, Denis; Tatar, Mohammad; Mokhtari, Mohammad

    2006-07-01

    Seismicity and fault plane solutions of earthquakes at the intersection between the Main Recent Fault (a right-lateral strike-slip fault that bounds the Zagros to the NE) and the Kazerun Fault system (another right-lateral zone that crosses the Zagros) show slip to be partitioned into nearly pure strike-slip at shallow depths and nearly pure thrust slip below 12 km. Such slip partitioning is commonly observed where oblique convergence occurs, but in general faults of different styles lie adjacent to one another, not at different depths with one below the other. We provide evidence for this partitioning in a microearthquake study in which we deployed a temporary network of 29 seismographs for 7 weeks. We located no activity north of the Main Zagros Reverse Fault (MZRF), which separates the Zagros fold belt from Central Iran. Most earthquakes occurred between the northern termination of the Kazerun Fault and the MZRF, but not near to known major faults. Activity is limited to the upper crust, between 2 and 16 km. Most of the focal mechanisms show strike-slip faulting, dextral if the NS striking plane is the active plane, but a few for the deepest events show reverse faulting, distributed between the Kazerun Fault and the MZRF, with P-axis trending consistently ~NS. This partitioning of the deformation with depth suggests that the brittle upper crust deforms by slip on pre-existing faults that strike obliquely but that the lower crust accommodates the shortening by reverse faulting. We infer that the deformation in the upper part of the crust reflects a stiffer medium in which pre-existing faults localize the deformation. The largest event recorded during this experiment, located at the same place as the destructive 1977 Naghan earthquake (Mw ~5.9, 348 victims), shows reverse faulting, likely related to the Dopolan High Zagros Fault. The crustal thickness deduced from receiver function analysis does not show a marked difference across the Kazerun fault, which suggests

  7. 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.

  8. Interpretation of the Reagan fault, Garvin, Johnston, Murray, and Stephens Counties, Oklahoma

    SciTech Connect

    McCaskill, J.G. )

    1993-09-01

    The Reagan fault, which lies between the Mill Creek syncline and the Tishomingo anticline, is one of the major faults in the Arbuckle Mountains. The fault's surface expression extends for more than 24 mi, and it can be traced in the subsurface at least an additional 26 mi west. The relative upthrown side of the fault changes at least four times along its length and it is manifest in different segments as both an apparent reverse fault and an apparent normal fault. Subsurface cross sections show abrupt facies changes within formations across the Reagan fault and isochore maps of individual units indicate a large-scale component of left-lateral movement along the fault. The geometry of the fault, as well as its displacement, also is consistent with a wrench-fault interpretation of the Reagan fault. Synorogenic conglomerates indicate that in at least one locality the Reagan fault had ceased movement, whereas the Washita Valley fault was still active.

  9. Has the San Gabriel fault been offset

    SciTech Connect

    Sheehan, J.R.

    1988-03-01

    The San Gabriel fault (SGF) in southern California is a right-lateral, strike-slip fault extending for 85 mi in an arcuate, southwestward-bowing curve from near the San Andreas fault at Frazier Mountain to its intersection with the left-lateral San Antonio Canyon fault (SACF) in the eastern San Gabriel Mountains. Termination of the SGF at the presently active SACF is abrupt and prompts the question Has the San Gabriel Fault been offset. Tectonic and geometric relationships in the area suggest that the SGF has been offset approximately 6 mi in a left-lateral sense and that the offset continuation of the SGF, across the SACF, is the right-lateral, strike-slip San Jacinto fault (SJF), which also terminates at the SACF. Reversing the left-lateral movement on the SACF to rejoin the offset ends of the SGF and SJF reveals a fault trace that is remarkably similar in geometry and movement (and perhaps in tectonic history), to the trace of the San Andreas fault through the southern part of the San Bernardino Mountains. The relationship of the Sierra Madre-Cucamonga fault system to the restored SGF-SJF fault is strikingly similar to the relationship of the Banning fault to the Mission Creek-Mill Creek portion of the San Andreas fault. Structural relations suggest that the San Gabriel-San Jacinto system predates the San Andreas fault in the eastern San Gabriel Mountains and that continuing movement on the SACF is currently affecting the trace of the San Andreas fault in the Cajon Pass area.

  10. 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.

  11. 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.

  12. Deformation characteristics and history along the Ilkwang Fault, SE Korea

    NASA Astrophysics Data System (ADS)

    Jin, K.; Kim, Y.; Yang, S.; Choi, J.

    2009-12-01

    The NNE-SSW trending Ilkwang Fault is one of the major structural features around SE Korea. It is a high angle, right-lateral strike-slip fault with a displacement of about 1.2 km. The basement around the fault is Cretaceous sedimentary and volcanic rocks forming a part of the Gyeongsang Basin in SE Korea, and it is intruded by later igneous rocks. The fault has not been studied intensively due to poor exposure along the fault. However, understanding the characteristics of the Ilkwang Fault is important because three nuclear power plants and one nuclear waste disposal site are located around the fault. We have mainly investigated along the new road-cut sections of the Busan-Ulsan Highway. Many geologic structures such as dykes, folds, and faults are measured in several studied sites. The analyzed structural patterns indicate multi-deformation including reactivation of pre-existing faults. In this study, we analyzed variation patterns of attitude on the beddings and fractures around some parts of the Ilkwang Fault. The strike/dip variation from the general attitude of the structural elements (e.g. beddings) is here used as an indicator of deformation intensity across the fault. This analysis indicates that respect distances (highly deformed area affected by faulting) along the Ilkwang Fault is about 1 km in sedimentary rocks and 200 m in volcanic rocks, respectively. It indicates that the Ilkwang Fault is a relatively big fault, and layered sedimentary rock is relatively weaker than massive volcanic rock under brittle deformation. Deformation history in the studied area, based on kinematic analysis of faults, joints and dykes, is as follows: 1) NNE-SSW trending reverse fault and fold. 2) E-W trending reverse fault and N-S trending acidic dykes. 3) ENE-WSW trending left-lateral fault, NNE-SSW trending right-lateral fault, and NE-SW trending basic dykes. 4) E-W trending normal fault. 5) N-S or NNE-SSW trending reverse fault.

  13. Surface breakthrough of a basement fault by repeated seismic slip episodes: The Ostler Fault, South Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Ghisetti, Francesca C.; Gorman, Andrew R.; Sibson, Richard H.

    2007-12-01

    The Ostler Fault is one of the major active reverse faults in the piedmont of the Southern Alps, SE of the Alpine Fault. We present a new geological and morphotectonic map of the southern Ostler Fault, integrated with two seismic reflection profiles across the active central segments of the fault. Segmented, subparallel scarps define a N-S belt (˜40 km long and 2-3 km wide) of pure reverse faults, which upthrow and back-tilt a panel of Plio-Pleistocene terrestrial units (2.4-1.0 Ma) plus the overlying glacial outwash (<200 ka). Uplift gradients, the chronology of newly faulted markers, and tectonically controlled diversion of paleodrainages, all indicate progressive S to N breakthrough of the surface trace of the Ostler Fault in the last 2.4 Ma. The new seismic data define a main fault segment dipping 50°-60°W to depths of ˜1.5 km, with a vertical throw of 800 m, and a shortening of ˜30%. The fault geometry and kinematics and the subsurface data favor the interpretation that the Ostler Fault propagated updip across the Plio-Quaternary terrestrial sequence as the emerging, high-angle splay of an inherited Late Cretaceous-Paleocene normal fault, that underwent repeated cycles of compressional reactivation in the last 2.4 Ma.

  14. Fault reactivation: The Picuris-Pecos fault system of north-central New Mexico

    NASA Astrophysics Data System (ADS)

    McDonald, David Wilson

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

  15. 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

  16. Poro-Elasto-Plastic Off-Fault Response and Dynamics of Earthquake Faulting

    NASA Astrophysics Data System (ADS)

    Hirakawa, Evan Tyler

    Previous models of earthquake rupture dynamics have neglected interesting deformational properties of fault zone materials. While most current studies involving off-fault inelastic deformation employ simple brittle failure yield criteria such as the Drucker-Prager yield criterion, the material surrounding the fault plane itself, known as fault gouge, has the tendency to deform in a ductile manner accompanied by compaction. We incorporate this behavior into a new constitutive model of undrained fault gouge in a dynamic rupture model. Dynamic compaction of undrained fault gouge occurs ahead of the rupture front. This corresponds to an increase in pore pressure which preweakens the fault, reducing the static friction. Subsequent dilatancy and softening of the gouge causes a reduction in pore pressure, resulting in fault restrengthening and brief slip pulses. This leads to localization of inelastic failure to a narrow shear zone. We extend the undrained gouge model to a study of self-similar rough faults. Extreme compaction and dilatancy occur at restraining and releasing bends, respectively. The consequent elevated pore pressure at restraining bends weakens the fault and allows the rupture to easily pass, while the decrease in pore pressure at releasing bends dynamically strengthens the fault and slows rupture. In comparison to other recent models, we show that the effects of fault roughness on propagation distance, slip distribution, and rupture velocity are diminished or reversed. Next, we represent large subduction zone megathrust earthquakes with a dynamic rupture model of a shallow dipping fault underlying an accretionary wedge. In previous models by our group [Ma, 2012; Ma and Hirakawa, 2013], inelastic deformation of wedge material was shown to enhance vertical uplift and potential tsunamigenesis. Here, we include a shallow region of velocity strengthening friction with a rate-and-state framework. We find that coseismic increase of the basal friction drives

  17. Flight elements: Fault detection and fault management

    NASA Technical Reports Server (NTRS)

    Lum, H.; Patterson-Hine, A.; Edge, J. T.; Lawler, D.

    1990-01-01

    Fault management for an intelligent computational system must be developed using a top down integrated engineering approach. An approach proposed includes integrating the overall environment involving sensors and their associated data; design knowledge capture; operations; fault detection, identification, and reconfiguration; testability; causal models including digraph matrix analysis; and overall performance impacts on the hardware and software architecture. Implementation of the concept to achieve a real time intelligent fault detection and management system will be accomplished via the implementation of several objectives, which are: Development of fault tolerant/FDIR requirement and specification from a systems level which will carry through from conceptual design through implementation and mission operations; Implementation of monitoring, diagnosis, and reconfiguration at all system levels providing fault isolation and system integration; Optimize system operations to manage degraded system performance through system integration; and Lower development and operations costs through the implementation of an intelligent real time fault detection and fault management system and an information management system.

  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

  19. The End Of Chi-Shan Fault:Tectonic of Transtensional Fault

    NASA Astrophysics Data System (ADS)

    Chou, H.; Song, G.

    2011-12-01

    Chishan fault is an active strike-slip fault that located at the Southwestern Taiwan and extend to the offshore area of SouShan in Kaohsiung. The strike and dip of the fault is N80E,50N. It's believed that the Wushan Formation of Chishan fault, which is composed of sandstone, thrusts upon the Northwestern Kutingkeng Formation, which is composed of mudstone. Chishan fault is acting as a reversal fault with sinistral motion. (Tsan and Keng,1968; Hsieh, 1970; Wen-Pu Geng, 1981). This left-lateral strike-slip fault extend to shelf break and stop, with a transtensional basin at the termination. The transtensional basin has stopped extending to open sea, whereas it is spreading toward the inshore area. Therefore, we can know that a young extensional activity is developing at the offshore seabed of Tsoying Naval Port and the activity is relative to the transtension of left-lateral fault. ( Gwo-Shyh Song, 2010). Tectonic of transtensional basin deformed in strike-slip settings overland have been described by many authors, but the field outcrop could be distoryed by Weathering and made the tectonic features incomplete. Hence, this research use multibeam bathymetry and 3.5-kHz sub-bottom profiler data data collected from the offshore extended part of Chishan fault in Kaohsiung to define the transtensional characteristics of Chishan fault. At first, we use the multibeam bathymetry data to make a Geomorphological map of our research area and we can see a triangulate depressed area near shelf break. Then, we use Fledermaus to print 3D diagram for understanding the distribution of the major normal faults(fig.1). Furthermore, we find that there are amount of listric normal fault and the area between the listric faults is curving. After that, we use the 3.5-kHz sub-bottom profiler data to understand the subsurface structure of the normal faults and the curved area between the listric normal fault, which seems to be En e'chelon folds. As the amount of displacement on the wrench

  20. Neotectonic faulting in northern Norway; the Stuoragurra and Nordmannvikdalen postglacial faults

    NASA Astrophysics Data System (ADS)

    Dehls, John F.; Olesen, Odleiv; Olsen, Lars; Harald Blikra, Lars

    2000-10-01

    A systematic compilation and characterisation of many reports of neotectonic crustal deformation in Norway (both on local and regional scales) has identified two neotectonic faults in northern Norway. The Stuoragurra Fault is a large reverse fault in Finnmark County. The Nordmannvikdalen fault is a much smaller normal fault in Troms County. The Stuoragurra postglacial fault can be followed, in several discontinuous sections, for 80 km, in a NE-SW direction. The fault has up to 10 m of displacement. During 1998, two trenches were made across the fault. The hanging wall was seen to be thrust upwards over the footwall, with 7 m vertical displacement evident from displaced glacial contacts. The fault did not penetrate the overlying glacial materials, but rather folded them, forming a blind thrust. Large liquefaction and other deformation structures were found in the glaciofluvial sediments in both trenches. Veins of angular and subangular pebbles from the local bedrock penetrate more than 10 m laterally from the thrust plane and into the sediments in the footwall. It is thought that these veins were injected during the fault activity. The major deformation of the sediments has a décollement plane that continues laterally in the E/B horizon contact of the modern soil on top of the footwall. This may indicate that an initial pedogenesis had taken place before the fault activity occurred, however no macro plant fossils to support this were found in the possible buried soil. Deformational structures seen in the trench can be explained as a result of one major fault event. The Nordmannvikdalen postglacial fault is a NW-SE trending normal fault, dipping to the NE. The fault offsets till on the NW slope of Nordmannvikdalen. The escarpment varies in height from 0.5 to 1.5 m, with a trench often present between the hanging wall and the footwall. The fault locally splits into two subparallel branches, however this is probably only in the glacial overburden. Ground penetrating

  1. Microstructural analysis of faulting in quartzite, Assynt, NW Scotland: Implications for fault zone evolution

    NASA Astrophysics Data System (ADS)

    Knipe, Robert J.; Lloyd, Geoffrey E.

    1994-03-01

    Macroscopic fracture arrays, microstructures and interpreted deformation mechanisms are used to assess the development of a minor reverse fault (backthrust) in quartzite from the Moine Thrust Zone, Assynt, NW Scotland. Fracturing dominates the faulting via the progression: intragranular extension microcracks; transgranular, cataclasite absent extension fractures; through-going, cataclasite filled shear microfaults, within which fracturing and particulate flow operate. However, both diffusive mass transfer (DMT) and intracrystalline plasticity (low temperature plasticity, LTP) processes also contribute to the fault zone deformation and lead to distinct associations of deformation mechanisms (e.g., DMT-fracture and LTP-fracture or low-temperature ductile fracture, LTDF). Over a large range of scales the fault zone consists of blocks of relatively intact rock separated by narrow zones of intense deformation where fracture processes dominate. The populations of fragments/blocks of different sizes in the fault zone have a power-law relationship which is related to the dimension of the fault zone. These observations are used to develop a general model for fault zone evolution based on the distribution of deformation features as a function of either time or space. A systematic variation in the deformation rate: time histories is recognised, associated with different positions within the fault zone. Thus, the fault zone preserves elements of the “birth, life and death” sequences associated with the displacement history and strain accommodation.

  2. Fault mirrors in seismically active fault zones: A fossil of small earthquakes at shallow depths

    NASA Astrophysics Data System (ADS)

    Kuo, Li-Wei; Song, Sheng-Rong; Suppe, John; Yeh, En-Chao

    2016-03-01

    Fault mirrors (FMs) are naturally polished and glossy fault slip surfaces that can record seismic deformation at shallow depths. They are important for investigating the processes controlling dynamic fault slip. We characterize FMs in borehole samples from the hanging wall damage zone of the active Hsiaotungshi reverse fault, Taiwan. Here we report the first documented occurrence of the combination of silica gel and melt patches coating FMs, with the silica gel resembling those observed on experimentally formed FMs that were cataclastically generated. In addition, the melt patches, which are unambiguous indicators of coseismic slip, suggest that the natural FMs were produced at seismic rates, presumably resulting from flash heating at asperities on the slip surfaces. Since flash heating is efficient at small slip, we propose that these natural FMs represent fossils of small earthquakes, formed in either coseismic faulting and folding or aftershock deformation in the active Taiwan fold-and-thrust belt.

  3. Earthquake recurrence and fault behavior on the Homestead Valley fault -- Central segment of the 1992 Landers surface rupture sequence

    SciTech Connect

    Cinti, F.R. ); Fumal, T.E.; Garvin, C.D.; Hamilton, J.C.; Powers, T.J.; Schwartz, D.P. )

    1993-04-01

    The 1992 M 7.5 Landers earthquake produced complex surface rupture on sections of the previously mapped Johnson Valley, Homestead Valley, and Emerson faults. The earthquake has raised questions about new faulting, characteristic earthquakes, and fault segmentation. To address these issues the authors initiated a study of both ruptured and unruptured fault segments, and report initial observations on the Homestead Valley fault (HVF). The authors site is located at the distal end of a large alluvial fan where 1992 right slip was 3 m, vertical slip was 40 cm, and the rupture followed pre-existing NE-facing scarps. Two trenches provide clear evidence of the two most recent pre-1992 surface faulting events. The trenches exposed alluvial fan and scarp derived colluvial deposits that are displaced and locally warped by both vertical strike-slip and low angle reverse-oblique( )-slip faults. At the main fault trace two pre-1992 colluvial wedges overlie a distinctive Bt soil horizon of late( ) Pleistocene age. Colluvium from the penultimate event has weak soil development, indicating a Holocene age for this faulting; apparent vertical displacement from this event is 35 cm, essentially the same as 1992. Preliminary observations indicate that recurrence of large magnitude earthquakes on faults of the Eastern California Shear Zone is one to two orders of magnitude longer than on major faults of the San Andreas system. The length of the HVF is short for this amount of offset, which suggests prior events may have also involved the rupture of multiple fault segments.

  4. Earthquake recurrence on the southern San Andreas modulated by fault-normal stress

    NASA Technical Reports Server (NTRS)

    Palmer, Randy; Weldon, Ray; Humphreys, Eugene; Saucier, Francois

    1995-01-01

    Earthquake recurrence data from the Pallett Creek and Wrightwood paleoseismic sites on the San Andreas fault appear to show temporal variations in repeat interval. We investigate the interaction between strike-slip faults and auxiliary reverse and normal faults as a physical mechanism capable of producing such variations. Under the assumption that fault strength is a function of fault-normal stress (e.g. Byerlee's Law), failure of an auxiliary fault modifies the strength of the strike-slip fault, thereby modulating the recurrence interval for earthquakes. In our finite element model, auxiliary faults are driven by stress accumulation near restraining and releasing bends of a strike-slip fault. Earthquakes occur when fault strength is exceeded and are incorporated as a stress drop which is dependent on fault-normal stress. The model is driven by a velocity boundary condition over many earthquake cycles. Resulting synthetic strike-slip earthquake recurrence data display temporal variations similar to observed paleoseismic data within time windows surrounding auxiliary fault failures. Our simple model supports the idea that interaction between a strike-slip fault and auxiliary reverse or normal faults can modulate the recurrence interval of events on the strike-slip fault, possibly producing short term variations in earthquake recurrence interval.

  5. Progressive deformation and degradation along the northern portion of the Big Bend of the San Andreas Fault

    SciTech Connect

    Arrowsmith, R. . Dept. of Geology)

    1992-01-01

    The 1-to-5-km-wide Elkhorn Hills in the southeastern Carrizo Plain, California (bounded by the San Andreas Fault (SAF) on the southwest and a series of reverse faults on the northeast), are progressively deformed as they are displaced along the SAF into the northern portion of the Big Bend. The structural development follows this sequence: (1) an alluvial fan surface is cut by reverse faults about 500 m northeast of the SAF, and grabens form in the foot-wall block of the faults; (2) a reverse fault striking 25 degrees counterclockwise from the SAF cuts the fan surface 2 to 3 km northeast of the SAF, left-stepping grabens form in the reverse fault hanging wall; their orientation is controlled by distributed SAF parallel shear and by dip variations in the reverse fault surface; (3) reverse faults accumulate displacement, increasing relief in the Elkhorn Hills, while hanging wall extension decreases; (4) slip on deeper thrusts accommodates contraction within the Big Bend, and Elkhorn Hills deformation decreases. Within the Northern Elkhorn Hills, the evidence for the development of deformation in time and space includes a southeastward increase in total displacement on the normal and reverse faults, a southeastward increase in the degradation of the normal fault scarps, and the beheading of a southwest flowing drainage by slip on the reverse fault, as well as cutting of that drainage by normal faults, implying contemporaneous propagation of normal and reverse faults. Based on a ground pattern age of 4 to 10 ka for the beheaded drainage and the present location of the reverse fault, a propagation rate of 3.5 to 10 cm/yr is calculated: consistent with the 3.5 cm/yr at which the Elkhorn Hills are displaced into the Big Bend by strike-slip motion along the SAF.

  6. Association of the 1886 Charleston, South Carolina, earthquake and seismicity near Summervile with a 12º bend in the East Coast fault system and triple-fault junctions

    USGS Publications Warehouse

    Marple, R.; Miller, R.

    2006-01-01

    Seismic-reflection data were integrated with other geophysical, geologic, and seismicity data to better determine the location and nature of buried faults in the Charleston, South Carolina, region. Our results indicate that the 1886 Charleston, South Carolina, earthquake and seismicity near Summerville are related to local stresses caused by a 12?? bend in the East Coast fault system (ECFS) and two triple-fault junctions. One triple junction is formed by the intersection of the northwest-trending Ashley River fault with the two segments of the ECFS north and south of the bend. The other triple junction is formed by the intersection of the northeast-trending Summerville fault and a newly discovered northwest-trending Berkeley fault with the ECFS about 10 km north of the bend. The Summerville fault is a northwest-dipping border fault of the Triassic-age Jedburg basin that is undergoing reverse-style reactivation. This reverse-style reactivation is unusual because the Summerville fault parallels the regional stress field axis, suggesting that the reactivation is from stresses applied by dextral motion on the ECFS. The southwest-dip and reverse-type motion of the Berkeley fault are interpreted from seismicity data and a seismic-reflection profile in the western part of the study area. Our results also indicate that the East Coast fault system is a Paleozoic basement fault and that its reactivation since early Mesozoic time has fractured through the overlying allochthonous terranes.

  7. Structural and geomorphic fault segmentations of the Doruneh Fault System, central Iran

    NASA Astrophysics Data System (ADS)

    Farbod, Yassaman; Bellier, Olivier; Shabanian, Esmaeil; Abbassi, Mohammad Reza

    2010-05-01

    characterized by the left-handed step-over geometry and its associated geomorphic features such as pull-apart basins, (2) The 100-km-long, E-trending central fault zone characterized by pure left-lateral offsets recorded by alluvial fan and drainage systems incised in, and (3) The 160-km-long, N115°E-trending eastern fault zone along which the active faulting is distributed into a 24-km-wide (maximum) fault zone characterized by Quaternary reverse faulting and thrust-parallel folding. At the regional scale, the eastern fault zone likes a horsetail fault termination for the DFS. Our results indicate that the central fault zone is a pure left-lateral strike-slip fault. Taking the northward convexity of the DFS into account, such a pure strike-slip faulting on the central fault zone involved (1) the eastern fault zone in a compressional regime, and (2) the western fault zone in a transtensional tectonic regime. These structural relationships led us to propose a tectonic model in which the central fault zone controls the deformation pattern and faulting mechanism on both terminations of the DFS.

  8. Earthquake faulting as a structural process

    NASA Astrophysics Data System (ADS)

    Sibson, Richard H.

    Structural geology is concerned with the history of movement in the Earth's crust and the processes by which displacements occur. In the upper one third to one half of deforming continental crust, displacement is accommodated largely by seismic slip increments on existing faults. It follows that earthquakes and related processes are an integral part of structural geology. Traditionally, structural geologists have been preoccupied with the complexity of the finite deformation within fault zones and with the stress states prevailing at the initiation of faults in intact crust. Future structural work should be directed more towards understanding the dynamic character of fault reactivation during incremental slip, and related effects. Questions of interest include rheological and geometrical controls on the initiation, perturbation and termination of ruptures; directivity effects associated with rupture propagation; the recognition of structures resulting from repeated stress cycling within seismogenic crust; and identification of structural features diagnostic of shear stress levels during faulting. Structures arising from the inter-relationships between slip episodes and induced fluid flow are of special importance, because these dynamic fault processes appear influential in the development of much fault-hosted mineralization. Mesothermal gold-quartz lodes hosted in high-angle reverse shear zones of mixed brittle-ductile character form illustrative examples of structures that, arguably, can only be interpreted by seismo-structural analysis embodying the concepts listed above.

  9. Fault tree handbook

    SciTech Connect

    Haasl, D.F.; Roberts, N.H.; Vesely, W.E.; Goldberg, F.F.

    1981-01-01

    This handbook describes a methodology for reliability analysis of complex systems such as those which comprise the engineered safety features of nuclear power generating stations. After an initial overview of the available system analysis approaches, the handbook focuses on a description of the deductive method known as fault tree analysis. The following aspects of fault tree analysis are covered: basic concepts for fault tree analysis; basic elements of a fault tree; fault tree construction; probability, statistics, and Boolean algebra for the fault tree analyst; qualitative and quantitative fault tree evaluation techniques; and computer codes for fault tree evaluation. Also discussed are several example problems illustrating the basic concepts of fault tree construction and evaluation.

  10. Aftershocks of the 2014 South Napa, California, Earthquake: Complex faulting on secondary faults

    USGS Publications Warehouse

    Hardebeck, Jeanne L.; Shelly, David R.

    2016-01-01

    We investigate the aftershock sequence of the 2014 MW6.0 South Napa, California, earthquake. Low-magnitude aftershocks missing from the network catalog are detected by applying a matched-filter approach to continuous seismic data, with the catalog earthquakes serving as the waveform templates. We measure precise differential arrival times between events, which we use for double-difference event relocation in a 3D seismic velocity model. Most aftershocks are deeper than the mainshock slip, and most occur west of the mapped surface rupture. While the mainshock coseismic and postseismic slip appears to have occurred on the near-vertical, strike-slip West Napa fault, many of the aftershocks occur in a complex zone of secondary faulting. Earthquake locations in the main aftershock zone, near the mainshock hypocenter, delineate multiple dipping secondary faults. Composite focal mechanisms indicate strike-slip and oblique-reverse faulting on the secondary features. The secondary faults were moved towards failure by Coulomb stress changes from the mainshock slip. Clusters of aftershocks north and south of the main aftershock zone exhibit vertical strike-slip faulting more consistent with the West Napa Fault. The northern aftershocks correspond to the area of largest mainshock coseismic slip, while the main aftershock zone is adjacent to the fault area that has primarily slipped postseismically. Unlike most creeping faults, the zone of postseismic slip does not appear to contain embedded stick-slip patches that would have produced on-fault aftershocks. The lack of stick-slip patches along this portion of the fault may contribute to the low productivity of the South Napa aftershock sequence.

  11. Aftershocks illuninate the 2011 Mineral, Virginia, earthquake causative fault zone and nearby active faults

    USGS Publications Warehouse

    Horton, Jr., J. Wright; Shah, Anjana K.; McNamara, Daniel E.; Snyder, Stephen L.; Carter, Aina M

    2015-01-01

    Deployment of temporary seismic stations after the 2011 Mineral, Virginia (USA), earthquake produced a well-recorded aftershock sequence. The majority of aftershocks are in a tabular cluster that delineates the previously unknown Quail fault zone. Quail fault zone aftershocks range from ~3 to 8 km in depth and are in a 1-km-thick zone striking ~036° and dipping ~50°SE, consistent with a 028°, 50°SE main-shock nodal plane having mostly reverse slip. This cluster extends ~10 km along strike. The Quail fault zone projects to the surface in gneiss of the Ordovician Chopawamsic Formation just southeast of the Ordovician–Silurian Ellisville Granodiorite pluton tail. The following three clusters of shallow (<3 km) aftershocks illuminate other faults. (1) An elongate cluster of early aftershocks, ~10 km east of the Quail fault zone, extends 8 km from Fredericks Hall, strikes ~035°–039°, and appears to be roughly vertical. The Fredericks Hall fault may be a strand or splay of the older Lakeside fault zone, which to the south spans a width of several kilometers. (2) A cluster of later aftershocks ~3 km northeast of Cuckoo delineates a fault near the eastern contact of the Ordovician Quantico Formation. (3) An elongate cluster of late aftershocks ~1 km northwest of the Quail fault zone aftershock cluster delineates the northwest fault (described herein), which is temporally distinct, dips more steeply, and has a more northeastward strike. Some aftershock-illuminated faults coincide with preexisting units or structures evident from radiometric anomalies, suggesting tectonic inheritance or reactivation.

  12. The Meers Fault in Southern Oklahoma: Holocene Movements on a Fault with Pennsylvanian and Cambrian Linages

    NASA Astrophysics Data System (ADS)

    Keller, G. R.; Holland, A. A.; Luza, K.; Oldow, J. S.; Crain, K.

    2011-12-01

    The Meers fault and subparallel fault strands in southern Oklahoma is the southernmost element of the complex and massive (>10 km of throw) frontal fault zone that forms the boundary between the Anadarko basin, which is the deepest intra-continental basin in the United States, and the uplifted Cambrian igneous rocks of the Wichita Mountains. The Wichita uplift is evidence of extraordinary Pennsylvanian intra-plate deformation along the trend of the Southern Oklahoma aulacogen, which is a classic example of a failed and massively inverted rift. The Meers Fault is the best-documented Holocene fault scarp east of Colorado and probably represents reactivation of a Pennsylvanian oblique thrust that in turn is likely to be an inverted Cambrian normal fault. The magnitude of these structures is shown on images from 3-D industry seismic reflection data ~25 km northwest of the northwestern mapped extent of the Meers fault that indicate the Pennsylvanian structure, or a northern strand of it, has a reverse throw of ~6km at depth. The fault displays a conspicuous and continuous scarp that is at least 25 km long and is evident in air photos and 1:100,000 scale geologic mapping, but this feature is not well mapped in detail beyond the area of trenching studies conducted in the 1980's. In the Holocene, 3-5 m of vertical surface displacement has been documented and left-lateral strike slip displacement on the fault is 2-3 times greater than the vertical displacement. During this movement, Quaternary soils along the fault were folded and ruptured, and the scarp has dammed small gullies where fine-grained alluvium has collected and has been used in the dating efforts. The most recent movement occurred (1100-1300 y ago) with a variety of earlier events having been proposed. As such, this fault represents one of the highest potential seismic hazards in the central/eastern United States.

  13. Hercynian basement faults control and hydrocarbon habitat in Morocco

    SciTech Connect

    Elouataoui, A.; Jabour, H.; Ait, S.A. )

    1996-01-01

    Geologic, geophysical and remote sensing evidence shows that the Paleozoic basement of Morocco is fragmented at various scales. Wrench faults, difficult to identify by conventional methods were examined from a regional perspective and through careful observation and assessment of many factors. Subsurface structural mapping and geoseismic cross-sections supported by outcrop studies and geomorphological features revealed a network of strike slip faults. Although controversy still surrounds interpretation of major faults as wrench type, with various amounts of strike-slip, or as reverse dip-slip with large amount of shortening, mapping of these basement fault block pattern in Moroccan sedimentary basins revealed literally many correlations of these blocks with prospective structures. These range from simple fault traps, to horst blocks, to fracture systems, to asymmetrical folds over reverse faults. Additionally, many types of stratigraphic traps correlate with basement shear zones. One example is the Middle Devonian algal mounds complex in the Doukkala Basin that evidently formed on fault scarps and/or fault-caused sea floor highs. The present study demonstrates that most of defined prospective structures in Morocco result from basement fault control and considers precise mapping of these pattern a pervasive and prerequisite exploration approach to go forward in upcoming exploration programs.

  14. Hercynian basement faults control and hydrocarbon habitat in Morocco

    SciTech Connect

    Elouataoui, A.; Jabour, H.; Ait, S.A.

    1996-12-31

    Geologic, geophysical and remote sensing evidence shows that the Paleozoic basement of Morocco is fragmented at various scales. Wrench faults, difficult to identify by conventional methods were examined from a regional perspective and through careful observation and assessment of many factors. Subsurface structural mapping and geoseismic cross-sections supported by outcrop studies and geomorphological features revealed a network of strike slip faults. Although controversy still surrounds interpretation of major faults as wrench type, with various amounts of strike-slip, or as reverse dip-slip with large amount of shortening, mapping of these basement fault block pattern in Moroccan sedimentary basins revealed literally many correlations of these blocks with prospective structures. These range from simple fault traps, to horst blocks, to fracture systems, to asymmetrical folds over reverse faults. Additionally, many types of stratigraphic traps correlate with basement shear zones. One example is the Middle Devonian algal mounds complex in the Doukkala Basin that evidently formed on fault scarps and/or fault-caused sea floor highs. The present study demonstrates that most of defined prospective structures in Morocco result from basement fault control and considers precise mapping of these pattern a pervasive and prerequisite exploration approach to go forward in upcoming exploration programs.

  15. Recurrent faulting and petroleum accumulation, Cat Creek Anticline, central Montana

    SciTech Connect

    Nelson, W.J. )

    1991-06-01

    The Cat Creek anticline, scene of central Montana's first significant oil discovery, is underlain by a south-dipping high-angle fault (Cat Creek fault) that has undergone several episodes of movement with opposite sense of displacement. Borehole data suggest that the Cat Creek fault originated as a normal fault during Proterozoic rifting concurrent with deposition of the Belt Supergroup. Reverse faulting took place in Late Cambrian time, and again near the end of the Devonian Period. The Devonian episode, coeval with the Antler orogeny, raised the southern block several hundred feet. The southern block remained high through Meramecian time, then began to subside. Post-Atokan, pre-Middle Jurassic normal faulting lowered the southern block as much as 1,500 ft. During the Laramide orogeny (latest Cretaceous-Eocene) the Cat Creek fault underwent as much as 4,000 ft of reverse displacement and a comparable amount of left-lateral displacement. The Cat Creek anticline is a fault-propagation fold; en echelon domes and listric normal faults developed along its crest in response to wrenching. Oil was generated mainly in organic-rich shales of the Heath Formation (upper Chesterian Series) and migrated upward along tectonic fractures into Pennsylvanian, Jurassic, and Cretaceous reservoir rocks in structural traps in en echelon domes. Production has been achieved only from those domes where structural closure was retained from Jurassic through Holocene time.

  16. Distribution of faults in a transition zone: Bimodal faulting in the Pit River region, Shasta County, California

    NASA Astrophysics Data System (ADS)

    Austin, L. J.; Weldon, R. J.; Paulson, K. T.

    2012-12-01

    Northern California marks a zone of transition between oblique subduction in Cascadia, dextral transtension in Walker Lane, and north-south compression of the Klamath Mountains. Because of its unique location, the region between Mt. Shasta and Lassen Peak provides insight into the distribution of deformation in regions of transitional tectonic regimes. In particular, the Pit River region provides several excellent exposures of faults in a diatomite quarry and in larger regional structures. We present information on the distribution, amount of slip, and orientation of local faults, and demonstrate how these data reflect the interaction of multiple regional stress fields. We have measured and compiled the orientations of many small faults to evaluate the distribution of deformation in a complex zone of oblique extension and compression. A ~0.5 km2 diatomite quarry near the Pit River and Lake Britton exposes hundreds of faults with small amounts of displacement. Two main faulting patterns emerge: 1) high angle NW/SE-striking faults characterized by normal, oblique normal, or strike slip kinematic indicators; and 2) lower angle E/W-striking faults with evidence of reverse to oblique reverse motion. We find that the regional landscape reflects a dominant mode of faulting that is NW/SE-striking normal, oblique normal, or strike slip; the Hat Creek and Rocky Ledge faults, each with tens of meters of oblique normal offset, exemplify this. Observations of numerous smaller faults in the diatomite quarry also show a dominant pattern of NW/SE-striking faults. E/W-striking compressional structures are present, but are less abundant. Faults of differing orientations occur together in the quarry and occasionally cross cut one another. Many faults cross but do not offset each other, indicating that they formed simultaneously. Where cross-cutting faults do exhibit offset, the NW/SE-striking faults offset E/W-striking faults, which suggests that NW/SE oriented faults have been

  17. 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

  18. Fault zone hydrogeology

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  19. An example of complex fault geometries in a young, rapidly deforming transform fault system: The Maacama Fault in northern California

    NASA Astrophysics Data System (ADS)

    Schroeder, R. D.; Brady, R. J.

    2009-12-01

    -existing structure, while the remaining two pull-aparts are newly formed. At several locations, the MFZ clearly reactivates pre-existing Franciscan subduction-related structures. Evidence of this includes the correlation of surface projections of seismogenic zones with outcrops of subduction related fault zones, and also best-fit planes through seismicity that have the same attitude as the pre-existing reverse faults that are seen in the Franciscan accretionary prism. Outcrops along these pre-existing fault zones have been analyzed by thin-section and XRD analysis, and include abundant mixed-layer clays, serpentine and chrysotile, and silica-carbonate. While each of these sheared deposits are evidence of a fault zone, the abundant clay in particular may be responsible for facilitating fault creep, such as the ~6.5 mm/yr seen on the main strand of the MFZ, and as has been suggested in the same formation at the SAFOD site in central California. The complexity of the MFZ is interpreted to result at least partially from the fact that it deforms heterogeneous Fransican mélange lithologies, which offer a closely spaced set of weak pre-existing fault planes that accommodate rapid displacement along the young San Andreas transform boundary.

  20. 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.

  1. Reversible Sterilization

    ERIC Educational Resources Information Center

    Largey, Gale

    1977-01-01

    Notes that difficult questions arise concerning the use of sterilization for alleged eugenic and euthenic purposes. Thus, how reversible sterilization will be used with relation to the poor, mentally ill, mentally retarded, criminals, and minors, is questioned. (Author/AM)

  2. Reversible Cardiomyopathies

    PubMed Central

    Patel, Harsh; Madanieh, Raef; Kosmas, Constantine E; Vatti, Satya K; Vittorio, Timothy J

    2015-01-01

    Cardiomyopathies (CMs) have many etiological factors that can result in severe structural and functional dysregulation. Fortunately, there are several potentially reversible CMs that are known to improve when the root etiological factor is addressed. In this article, we discuss several of these reversible CMs, including tachycardia-induced, peripartum, inflammatory, hyperthyroidism, Takotsubo, and chronic illness–induced CMs. Our discussion also includes a review on their respective pathophysiology, as well as possible management solutions. PMID:26052233

  3. Shallow subsurface geological investigation near the Meers fault, Oklahoma

    SciTech Connect

    Luza, K.V. )

    1993-02-01

    The Meers fault is part of a complex system of northwest-trending faults forming the boundary between the Wichita Mountains (south) and the Anadarko basin (north). The frontal fault system is dominated by moderately dipping to steeply dipping reverse faults which have a combined net vertical displacement of over 9 km. Of these faults, the Meers fault has a Pennsylvanian-Permian throw of about 2 km. The Meers fault trends N. 60[degree]W. and displaces Permian conglomerate and shale for a distance of at least 26 km, from near the Comanche-Kiowa County boundary to East Cache Creek. At the northwest end of the fault trace, the fault displaces limestone-pebble conglomerates (Post Oak), whereas at the southeast end siltstones and calcrete-bearing shales of the Hennessey are displaced. Multiple radiocarbon ages of soil-humus samples from 2 Canyon Creek trenches (S24, T4N, R13W) show the last surface faulting occurred 1,200--1,300 yr ago. In 1988--89, the Oklahoma Geological Survey drilled 4 core holes to basement in the vicinity of the trench sites. The holes were drilled along a 200-m-long transect normal to the strike of the Meers fault. Two holes were drilled on the north side of the fault and penetrated highly fractured and altered rhyolite at about 58 m. A third hole drilled 25 m south of the fault, intersected weathered and sheared gabbro at 58 m. The basement material in the fourth hole consisted of dark greenish brown, highly fractured and sheared rock. The drill holes encountered Permian, poorly sorted, matrix-supported, 0.5--3 m thick, conglomerate interbedded with shale and siltstone. Drill holes 1--3 contained 3--5 m thick, granite cobble-boulder, clast supported conglomerate resting on rhyolite and/or gabbro. The core-hole information suggests the Meers-fault zone is at least 200 meters wide.

  4. Injection-induced seismicity on basement faults including poroelastic stressing

    NASA Astrophysics Data System (ADS)

    Chang, K. W.; Segall, P.

    2016-04-01

    Most significant induced earthquakes occur on faults within the basement beneath sedimentary cover. In this two-dimensional plane strain numerical study, we examine the full poroelastic response of basement faults to fluid injection into overlying strata, considering both (1) the permeability of the fault zone and (2) the hydraulic connectivity of the faults to the target horizon. Given hydraulic and mechanical properties, we compute the spatiotemporal change in Coulomb stress, which we separate into (1) the change in poroelastic stresses Δτs+fΔσn, where Δτs and Δσn are changes in shear and normal stress (Δτs>0 and Δσn>0 both favor slip), and (2) the change in pore pressure fΔp. Pore pressure diffusion into hydraulically connected, permeable faults dominates their mechanical stability. For hydraulically isolated or low-permeability faults, however, poroelastic stresses transmitted to deeper basement levels can trigger slip, even without elevated pore pressure. The seismicity rate on basement fault zones is predicted using the model of Dieterich (1994). High seismicity rates can occur on permeable, hydraulically connected faults due to direct pore pressure diffusion. Lower rates are predicted on isolated steeply dipping normal faults, caused solely by poroelastic stressing. In contrast, seismicity on similarly oriented reverse faults is inhibited.

  5. Fault model development for fault tolerant VLSI design

    NASA Astrophysics Data System (ADS)

    Hartmann, C. R.; Lala, P. K.; Ali, A. M.; Visweswaran, G. S.; Ganguly, S.

    1988-05-01

    Fault models provide systematic and precise representations of physical defects in microcircuits in a form suitable for simulation and test generation. The current difficulty in testing VLSI circuits can be attributed to the tremendous increase in design complexity and the inappropriateness of traditional stuck-at fault models. This report develops fault models for three different types of common defects that are not accurately represented by the stuck-at fault model. The faults examined in this report are: bridging faults, transistor stuck-open faults, and transient faults caused by alpha particle radiation. A generalized fault model could not be developed for the three fault types. However, microcircuit behavior and fault detection strategies are described for the bridging, transistor stuck-open, and transient (alpha particle strike) faults. The results of this study can be applied to the simulation and analysis of faults in fault tolerant VLSI circuits.

  6. 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.

  7. 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.

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

    NASA Astrophysics Data System (ADS)

    Tsai, Timothy K.; Iyer, Ravishankar K.

    1994-07-01

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

  9. 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.

  10. Displacement–length scaling of brittle faults in ductile shear

    PubMed Central

    Grasemann, Bernhard; Exner, Ulrike; Tschegg, Cornelius

    2011-01-01

    Within a low-grade ductile shear zone, we investigated exceptionally well exposed brittle faults, which accumulated antithetic slip and rotated into the shearing direction. The foliation planes of the mylonitic host rock intersect the faults approximately at their centre and exhibit ductile reverse drag. Three types of brittle faults can be distinguished: (i) Faults developing on pre-existing K-feldspar/mica veins that are oblique to the shear direction. These faults have triclinic flanking structures. (ii) Wing cracks opening as mode I fractures at the tips of the triclinic flanking structures, perpendicular to the shear direction. These cracks are reactivated as faults with antithetic shear, extend from the parent K-feldspar/mica veins and form a complex linked flanking structure system. (iii) Joints forming perpendicular to the shearing direction are deformed to form monoclinic flanking structures. Triclinic and monoclinic flanking structures record elliptical displacement–distance profiles with steep displacement gradients at the fault tips by ductile flow in the host rocks, resulting in reverse drag of the foliation planes. These structures record one of the greatest maximum displacement/length ratios reported from natural fault structures. These exceptionally high ratios can be explained by localized antithetic displacement along brittle slip surfaces, which did not propagate during their rotation during surrounding ductile flow. PMID:26806996

  11. 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.

  12. Active tectonics of the Seattle fault and central Puget sound, Washington - Implications for earthquake hazards

    USGS Publications Warehouse

    Johnson, S.Y.; Dadisman, S.V.; Childs, J. R.; Stanley, W.D.

    1999-01-01

    We use an extensive network of marine high-resolution and conventional industry seismic-reflection data to constrain the location, shallow structure, and displacement rates of the Seattle fault zone and crosscutting high-angle faults in the Puget Lowland of western Washington. Analysis of seismic profiles extending 50 km across the Puget Lowland from Lake Washington to Hood Canal indicates that the west-trending Seattle fault comprises a broad (4-6 km) zone of three or more south-dipping reverse faults. Quaternary sediment has been folded and faulted along all faults in the zone but is clearly most pronounced along fault A, the northernmost fault, which forms the boundary between the Seattle uplift and Seattle basin. Analysis of growth strata deposited across fault A indicate minimum Quaternary slip rates of about 0.6 mm/yr. Slip rates across the entire zone are estimated to be 0.7-1.1 mm/yr. The Seattle fault is cut into two main segments by an active, north-trending, high-angle, strike-slip fault zone with cumulative dextral displacement of about 2.4 km. Faults in this zone truncate and warp reflections in Tertiary and Quaternary strata and locally coincide with bathymetric lineaments. Cumulative slip rates on these faults may exceed 0.2 mm/yr. Assuming no other crosscutting faults, this north-trending fault zone divides the Seattle fault into 30-40-km-long western and eastern segments. Although this geometry could limit the area ruptured in some Seattle fault earthquakes, a large event ca. A.D. 900 appears to have involved both segments. Regional seismic-hazard assessments must (1) incorporate new information on fault length, geometry, and displacement rates on the Seattle fault, and (2) consider the hazard presented by the previously unrecognized, north-trending fault zone.

  13. Late Quaternary slip on the Santa Cruz Island fault, California

    USGS Publications Warehouse

    Pinter, N.; Lueddecke, S.B.; Keller, E.A.; Simmons, K.R.

    1998-01-01

    The style, timing, and pattern of slip on the Santa Cruz Island fault were investigated by trenching the fault and by analysis of offset late Quaternary landforms. A trench excavated across the fault at Christi Beach, on the western coast of the island, exposed deformation of latest Pleistocene to Holocene sediments and pre-Quaternary rocks, recording repeated large-magnitude rupture events. The most recent earthquake at this site occurred ca. 5 ka. Coastal terraces preserved on western Santa Cruz Island have been dated using the uranium-series technique and by extrapolation using terrace elevations and the eustatic record. Offset of terraces and other landforms indicates that the Santa Cruz Island fault is predominantly left lateral, having a horizontal slip rate of not more than 1.1 mm/yr and probably about 0.8 mm/yr. The fault also has a smaller reverse component, slipping at a rate of between 0.1 and 0.2 mm/yr. Combined with measurements of slip per event, this information suggests a long-term average recurrence interval of at least 2.7 k.y. and probably 4-5 k.y., and average earthquake magnitudes of Mw 7.2-7.5. Sense of slip, recurrence interval, and earthquake magnitudes calculated here for the Santa Cruz Island fault are very similar to recent results for other faults along the southern margin of the western Transverse Range, including the Malibu Coast fault, the Santa Monica fault, the Hollywood fault, and the Raymond fault, supporting the contention that these faults constitute a continuous and linked fault system, which is characterized by large but relatively infrequent earthquakes.

  14. Relationship between displacement and gravity change of Uemachi faults and surrounding faults of Osaka basin, Southwest Japan

    NASA Astrophysics Data System (ADS)

    Inoue, N.; Kitada, N.; Kusumoto, S.; Itoh, Y.; Takemura, K.

    2011-12-01

    The Osaka basin surrounded by the Rokko and Ikoma Ranges is one of the typical Quaternary sedimentary basins in Japan. The Osaka basin has been filled by the Pleistocene Osaka group and the later sediments. Several large cities and metropolitan areas, such as Osaka and Kobe are located in the Osaka basin. The basin is surrounded by E-W trending strike slip faults and N-S trending reverse faults. The N-S trending 42-km-long Uemachi faults traverse in the central part of the Osaka city. The Uemachi faults have been investigated for countermeasures against earthquake disaster. It is important to reveal the detailed fault parameters, such as length, dip and recurrence interval, so on for strong ground motion simulation and disaster prevention. For strong ground motion simulation, the fault model of the Uemachi faults consist of the two parts, the north and south parts, because of the no basement displacement in the central part of the faults. The Ministry of Education, Culture, Sports, Science and Technology started the project to survey of the Uemachi faults. The Disaster Prevention Institute of Kyoto University is carried out various surveys from 2009 to 2012 for 3 years. The result of the last year revealed the higher fault activity of the branch fault than main faults in the central part (see poster of "Subsurface Flexure of Uemachi Fault, Japan" by Kitada et al., in this meeting). Kusumoto et al. (2001) reported that surrounding faults enable to form the similar basement relief without the Uemachi faults model based on a dislocation model. We performed various parameter studies for dislocation model and gravity changes based on simplified faults model, which were designed based on the distribution of the real faults. The model was consisted 7 faults including the Uemachi faults. The dislocation and gravity change were calculated based on the Okada et al. (1985) and Okubo et al. (1993) respectively. The results show the similar basement displacement pattern to the

  15. The Van Fault, Eastern Turkey: A Preliminary Geological Slip Rate

    NASA Astrophysics Data System (ADS)

    Mackenzie, D.; Elliott, J. R.; Altunel, E.; Kurban, Y.; Walker, R. T.; Parsons, B.

    2014-12-01

    We present a preliminary quaternary slip-rate study on the Van fault, the source of the 2011 Mw7.1 reverse-slip earthquake which caused heavy damage to the cities of Van and Ercis, eastern Turkey. From the InSAR solution, we see a strong depth cut-off at 10km depth, above which there was no slip on the fault. We have carried out an investigation of the geomorphological expression of the fault in quaternary material, to determine whether the fault reaches the surface and, if so, whether this upper section could fail in an earthquake. On the western segment of the Van fault, we observe quaternary scarps coincident with the surface projection of the fault segment identified by InSAR, which displace quaternary alluvial fan and lake-bed deposits. These are coincident with the observation of fault gouge in quaternary deposits at a road cutting, providing evidence for a fault reaching the surface and suggesting that the upper section is capable of rupturing seismically. We use structure-from-motion photogrammetry, differential GPS and terrestrial LiDAR to determine offsets on two generations of fault scarps, and the creep offsets from the period following the earthquake. Preliminary radiocarbon and OSL dates from two uplifted terrace surfaces allow us to estimate a late quaternary geological slip-rate for the fault. Following the GPS and InSAR solution of Dogan et al. 2014 (GRL v41,i7), we also present field evidence and satellite image observations confirming the presence of a splay fault within the northern suburbs of Van city, which experienced creep following the 2011 earthquake. This fault is observed to be particularly evident in the early high resolution satellite imagery from the declassified CORONA missions, highlighting the potential for these datasets in identifying faults in areas now covered by urban sprawl. It remains unclear whether this fault could fail seismically. The fault which failed in 2011 is a north dipping reverse fault, unmapped prior to the

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

    SciTech Connect

    Iranpanah, A.

    1988-01-01

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

  17. Three-dimensional fault drawing

    SciTech Connect

    Dongan, L. )

    1992-01-01

    In this paper, the author presents a structure interpretation based on three-dimensional fault drawing. It is required that fault closure must be based on geological theory, spacial plotting principle and restrictions in seismic exploration. Geological structure can be well ascertained by analysing the shapes and interrelation of the faults which have been drawn through reasonable fault point closure and fault point correlation. According to this method, the interrelation of fault points is determined by first closing corresponding fault points in intersecting sections, then reasonably correlating the relevant fault points. Fault point correlation is not achieved in base map, so its correctness can be improved greatly. Three-dimensional fault closure is achieved by iteratively revising. The closure grid should be densified gradually. The distribution of major fault system is determined prior to secondary faults. Fault interpretation by workstation also follows this procedure.

  18. Brittle fault analysis from the immediate southern side of the Insubric fault

    NASA Astrophysics Data System (ADS)

    Pleuger, Jan; Mancktelow, Neil

    2013-04-01

    The Insubric segment of the Periadriatic fault is characterised in its central part between Lago Maggiore and Valle d'Ossola by two greenschist-facies mylonitic belts which together are about 1 km thick. The northern, external belt has a north-side-up kinematics generally with a minor dextral component and the southern internal belt is dextral, locally with a considerable south-side-up component. Overprinting relations locally show that the internal belt is younger than the external one (e.g. Schmid et al., 1987). The absolute age of dextral shearing is probably given by K-Ar white mica ages ranging mostly between from c. 27 to 23 Ma (Zingg and Hunziker, 1990). We analysed fault-slip data from various locations in the Southern Alps immediately south of the Insubric Fault. From the results, two different patterns of orientations of contraction (P-axes) and extension (T-axes) axes can be distinguished. One group (group 1) of analyses is compatible with dextral transpression (i.e. both P- and T-axes are subhorizontal) and the other (group 2) with roughly orogen-perpendicular extension (i.e. subvertical P-axes and subhorizontal T-axes). The orientations of subhorizontal axes (P- and T-axes in group 1, T-axes in group 2) show a tendency to follow the curved shape of the Insubric fault, i.e. P-axes of group 1 and T-axes of group 2 change from NNW-SSE in the east where the Insubric fault trends east-west to WNW-ESE in the west where the Insubric fault trends northeast-southwest. We speculate that group 1 formed at the same time as dextral shearing on in the internal mylonite belt while none of our fault analyses reflects the north-side-up reverse faulting that is observed in the external mylonite belt. The northwest-southeast extension documented in the analyses of group 2 is not associated with a continuous mylonitic belt or brittle fault plane along the Insubric fault. Instead, an uplift of the Southern Alps with respect to the northern block was accommodated by

  19. Polymodal faulting: Time for a new angle on shear failure

    NASA Astrophysics Data System (ADS)

    Healy, David; Blenkinsop, Thomas G.; Timms, Nicholas E.; Meredith, Philip G.; Mitchell, Thomas M.; Cooke, Michele L.

    2015-11-01

    Conjugate, or bimodal, fault patterns dominate the geological literature on shear failure. Based on Anderson's (1905) application of the Mohr-Coulomb failure criterion, these patterns have been interpreted from all tectonic regimes, including normal, strike-slip and thrust (reverse) faulting. However, a fundamental limitation of the Mohr-Coulomb failure criterion - and others that assume faults form parallel to the intermediate principal stress, σ2 - is that only plane strain can result from slip on the conjugate faults. However, deformation in the Earth is widely accepted as being three-dimensional, with truly triaxial stresses (σ1 > σ2 > σ3) and strains. Polymodal faulting, with three or more sets of faults forming and slipping simultaneously, can generate three-dimensional strains from truly triaxial stresses. Laboratory experiments and outcrop studies have verified the occurrence of polymodal fault patterns in nature. These fault patterns present a fundamental challenge to our understanding of shear failure in rocks (and other materials) and an opportunity to improve our understanding of seismic hazards and fluid flow in the subsurface. In this review, we assess the published evidence, theories and models for polymodal faulting before suggesting ways to produce a truly general and valid failure criterion for triaxial failure.

  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. Block Island fault: a Paleozoic crustal boundary on the Long Island platform

    USGS Publications Warehouse

    Hutchinson, Deborah R.; Klitgord, Kim D.; Detrick, R. S.

    1985-01-01

    A major fault cutting through most of the crust can be identified and mapped on the Long Island platform using multichannel seismic reflection profiles and magnetic data. The fault, here called the Block Island fault (BIF), strikes north-northeast, dips westward at low angle, and does not resemble the thin-skinned thrust faulting observed in the foreland of the Appalachians. The BIF is located within the hinterland of the Appalachian mountain belt in the collision zone between Africa and North America. We present several interpretations but favor one in which the fault originated as an east-verging mid–late Paleozoic thrust fault, possibly related to the collision of Avalon or Meguma with North America. It was probably reactivated during early Mesozoic continental breakup and again in the Late Cretaceous and Tertiary, causing the steeply dipping postrift New Shoreham fault to form, either as an antithetic (normal) or splay (reverse) fault.

  2. Surface ruptures on the transverse Xiaoyudong fault: A significant segment boundary breached during the 2008 Wenchuan earthquake, China

    NASA Astrophysics Data System (ADS)

    Liu-Zeng, Jing; Sun, Jing; Wang, Peng; Hudnut, Kenneth W.; Ji, Chen; Zhang, Zhihui; Xu, Qiang; Wen, Li

    2012-12-01

    The ~ 220 km-long rupture of the 2008 Mw 7.9 Wenchuan earthquake breached several km-scale geometric discontinuities along strike, including the previously un-mapped NW-trending Xiaoyudong fault, connecting between the two major, NE-trending rupture planes on the Beichuan and Pengguan Faults. In this paper, we present high-resolution mapping of the 8-km-long surface breaks and sinistral oblique thrusting coseismic slip on the Xiaoyudong fault. Scarp height is the largest at the NW end, reaching 3.5 m, and decreases southward in steps to less than 0.2 m, with an average slip gradient of 6 × 10- 3 at a few tens of meters length scale, but up to 50 × 10- 3 locally. Left-lateral offsets co-vary with the vertical component. The largest sinistral slip vector we observed is 2.2 m. Geological and geophysical evidence suggests that the Xiaoyudong fault is likely a ~ 30°SW-dipping lateral ramp that soles into the Pengguan fault, and at its northwestern end intersects with the Beichuan fault, where the latter has a step in the fault plane. Kinematically, the Xiaoyudong fault functions as a tear and conjugate fault and coincides with significant coseismic slip rake rotations on both the Beichuan and Pengguan Faults. Similar correlation of fault bends with sharp changes in faulting style occurs at other steps along the Wenchuan rupture. The Xiaoyudong fault may have played a positive role in linking coseismic slip partitioning between parallel reverse fault planes, facilitating the growth of a longer and more destructive rupture. This highlights the role of tear faults in bridging ruptures between segments, such that reverse-type ruptures can breach steps wider than anticipated from strike-slip fault examples. Transfer faults are common, and perhaps poorly documented features in reverse fault systems and their roles in ruptures may increase the maximum potential earthquake magnitude for fold-and-thrust belts.

  3. The effect of mechanical discontinuities on the growth of faults

    NASA Astrophysics Data System (ADS)

    Bonini, Lorenzo; Basili, Roberto; Bonanno, Emanuele; Toscani, Giovanni; Burrato, Pierfrancesco; Seno, Silvio; Valensise, Gianluca

    2016-04-01

    The growth of natural faults is controlled by several factors, including the nature of host rocks, the strain rate, the temperature, and the presence of fluids. In this work we focus on the mechanical characteristics of host rocks, and in particular on the role played by thin mechanical discontinuities on the upward propagation of faults and on associated secondary effects such as folding and fracturing. Our approach uses scaled, analogue models where natural rocks are simulated by wet clay (kaolin). A clay cake is placed above two rigid blocks in a hanging wall/footwall configuration on either side of a planar fault. Fault activity is simulated by motor-controlled movements of the hanging wall. We reproduce three types of faults: a 45°-dipping normal fault, a 45°-dipping reverse fault and a 30°-dipping reverse fault. These angles are selected as representative of most natural dip-slip faults. The analogues of the mechanical discontinuities are obtained by precutting the wet clay cake before starting the hanging wall movement. We monitor the experiments with high-resolution cameras and then obtain most of the data through the Digital Image Correlation method (D.I.C.). This technique accurately tracks the trajectories of the particles of the analogue material during the deformation process: this allows us to extract displacement field vectors plus the strain and shear rate distributions on the lateral side of the clay block, where the growth of new faults is best seen. Initially we run a series of isotropic experiments, i.e. experiments without discontinuities, to generate a reference model: then we introduce the discontinuities. For the extensional models they are cut at different dip angles, from horizontal to 45°-dipping, both synthetic and antithetic with respect to the master fault, whereas only horizontal discontinuities are introduced in the contractional models. Our experiments show that such discontinuities control: 1) the propagation rate of faults

  4. Vasectomy reversal.

    PubMed

    Belker, A M

    1987-02-01

    A vasovasostomy may be performed on an outpatient basis with local anesthesia, but also may be performed on an outpatient basis with epidural or general anesthesia. Local anesthesia is preferred by most of my patients, the majority of whom choose this technique. With proper preoperative and intraoperative sedation, patients sleep lightly through most of the procedure. Because of the length of time often required for bilateral microsurgical vasoepididymostomy, epidural or general anesthesia and overnight hospitalization are usually necessary. Factors influencing the preoperative choice for vasovasostomy or vasoepididymostomy in patients undergoing vasectomy reversal are considered. The preoperative planned choice of vasovasostomy or vasoepididymostomy for patients having vasectomy reversal described herein does not have the support of all urologists who regularly perform these procedures. My present approach has evolved as the data reported in Tables 1 and 2 have become available, but it may change as new information is evaluated. However, it offers a logical method for planning choices of anesthesia and inpatient or outpatient status for patients undergoing vasectomy reversal procedures. PMID:3811050

  5. Solar system fault detection

    DOEpatents

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

    1984-05-14

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

  6. 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.

  7. How clays weaken faults.

    NASA Astrophysics Data System (ADS)

    van der Pluijm, Ben A.; Schleicher, Anja M.; Warr, Laurence N.

    2010-05-01

    The weakness of upper crustal faults has been variably attributed to (i) low values of normal stress, (ii) elevated pore-fluid pressure, and (iii) low frictional strength. Direct observations on natural faults rocks provide new evidence for the role of frictional properties on fault strength, as illustrated by our recent work on samples from the San Andreas Fault Observatory at Depth (SAFOD) drillhole at Parkfield, California. Mudrock samples from fault zones at ~3066 m and ~3296 m measured depth show variably spaced and interconnected networks of displacement surfaces that consist of host rock particles that are abundantly coated by polished films with occasional striations. Transmission electron microscopy and X-ray diffraction study of the surfaces reveal the occurrence of neocrystallized thin-film clay coatings containing illite-smectite (I-S) and chlorite-smectite (C-S) phases. X-ray texture goniometry shows that the crystallographic fabric of these faults rocks is characteristically low, in spite of an abundance of clay phases. 40Ar/39Ar dating of the illitic mix-layered coatings demonstrate recent crystallization and reveal the initiation of an "older" fault strand (~8 Ma) at 3066 m measured depth, and a "younger" fault strand (~4 Ma) at 3296 m measured depth. Today, the younger strand is the site of active creep behavior, reflecting continued activation of these clay-weakened zones. We propose that the majority of slow fault creep is controlled by the high density of thin (< 100nm thick) nano-coatings on fracture surfaces, which become sufficiently smectite-rich and interconnected at low angles to allow slip with minimal breakage of stronger matrix clasts. Displacements are accommodated by localized frictional slip along coated particle surfaces and hydrated smectitic phases, in combination with intracrystalline deformation of the clay lattice, associated with extensive mineral dissolution, mass transfer and continued growth of expandable layers. The

  8. Study of Anisotropy of Magnetic Susceptibility on Central Chimei Fault, Coastal Range of Eastern Taiwan

    NASA Astrophysics Data System (ADS)

    Rong, C. Y.

    2014-12-01

    The Chimei fault is the only major reverse fault across the entire Coastal Range and is also a typical lithology-contrast fault thrusting the volcanic Tuluanshan Formation of Miocene over the sedimentary Paliwan Formation of Pleistocene. To investigate the deformation pattern across the Chimei fault more precisely, we analyzed oriented coring samples of mudstone across the fault zone, damage zone, fold zone and wall rocks along the Hsiukuluan River via anisotropy of magnetic susceptibility (AMS). Prolate (cigar-shaped) and oblate (disc-shaped) ellipsoids appear together at fault zone, damage zone and fold zone, suggesting that strong variation of deformation and lithology in each zone of the Chimei fault. Previous study pointed out that oblate ellipsoid usually appears in the footwall, further indicating that the Chimei fault behaves differently from regular detachment faults. It strongly speculates although the central Chimei fault displays N-S shortening, the deformation is not strong enough to develop penetrative oblate fabric, even in the main fault zone of the Chimei fault. Further studies will be rnrformation is not sobear theequired to identify the magnetic carriers and grain size to improve current concept. Keywords : Anisotropy of Magnetic Susceptibility, Coastal Range, Chimei Fault, Taiwan

  9. Kinematic vicissitudes and the spatial distribution of the alteration zone related to the Byobuyama fault, central Japan. (Implication; Influence of another faults.)

    NASA Astrophysics Data System (ADS)

    Katori, T.; Kobayashi, K.

    2015-12-01

    The central Japan is one of the most concentrated area of active faults (Quaternary fault). These are roughly classified into two orthogonally-oriented fault sets of NE-SW and NW-SE strikes. The study area is located in Gifu prefecture, central Japan. In there, the basement rocks are composed mainly of Triassic-Jurassic accretionary prism (Mino belt), Cretaceous Nohi Rhyolite and Cretaceous granitic rocks. Miocene Mizunami G. and Pliocene-Pleistocene Toki Sand and Gravel F. unconformably cover the basement rocks. The Byobuyama fault, 32 km in length, is NE-SW strike and displaces perpendicularly the Toki Sand and Gravel F. by 500 m. The northeastern terminal of the fault has contact with the southern terminal of the Atera fault of NW-SE strike and offset their displacements each other. It is clear that the activity of the Byobuyama fault plays a role of the development of the complicated fault geometry system in the central Japan. In this study, we performed a broad-based investigation along the Byobuyama fault and collected samples. Actually, we observed 400 faults and analyzed 200 fault rocks. Based on these results, we obtained the following new opinion. 1. The Byobuyama fault has experienced following activities that can be divided to 3 stages at least under different stress field. 1) Movement with the sinisterly sense (preserved in cataclasite zone). 2) Dextral movement (preserved in fault gouge zone). 3) Reverse fault movement (due to the aggressive rise of mountains). In addition, the change from Stage 2 to Stage 3 is a continuous. 2. There is a relationship between the distance from the trace of the Byobuyama fault and the combination of alteration minerals included in the fault rocks. 3. In the central part of the Byobuyama fault (CPBF), fault plane trend and combination of alteration minerals shows specific features. The continuous change is considered to mean the presence of factors that interfere with the dextral movement of the Byobuyama fault. What is

  10. 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

  11. Fluid-rock reaction weakening of fault zones

    SciTech Connect

    Wintsch, R.P.; Christoffersen, R.; Kronenberg, A.K.

    1995-07-10

    The presence of weak phyllosilicates may explain the low shear strengths of fault zones if they define well-developed fabrics. The growth of phyllosilicates is favored in meteoric water-dominated granitic fault systems, where mineral-aqueous fluid equilibria predict that modal phyllosilicate will increase via feldspar replacement reactions. In deeper, more alkaline, rock-dominated regimes, the reactions reverse, and feldspars tend to replace phyllosilicates. In Mg-rich mafic rocks, however, phyllosilicates (chlorite, biotite) can replace stronger framework and chain silicates in both shallower (<{approximately}10 km) meteoric H{sub 2}O-dominated and in deeper, alkaline, rock-dominated regimes. Where these phyllosilicates precipitate in active fault zones, they contribute directly to reaction softening. Because low-temperature deformation of phyllosilicates is not governed by frictional processes alone but can occur by pressure-independent dislocation glide, the strength of phyllosilicate-rich fault rocks can be low at all depths. Low strain rate creep during interseismic periods can align phyllosilicate grains in foliated gouge and phyllonites. Where preferred orientations are strong and contiguity of phyllosilicates is large, strengths of rocks within fault zones may approach minimum strengths defined by single phyllosilicate crystals. Fault zones containing localized high concentrations of phyllosilicates with strong preferred orientations in well-defined folia can exhibit aseismic slip, especially where mafic Mg-rich rocks occur along the fault (like parts of the San Andreas Fault). 104 refs., 6 figs., 1 tab.

  12. San Andreas fault zone head waves near Parkfield, California

    SciTech Connect

    Ben-Zion, Y.; Malin, P. Univ. of California, Santa Barbara, CA )

    1991-03-29

    Microearthquakes seismograms from the borehole seismic network on the San Andreas Fault near Parkfield, California, provide three lines of evidence that first P arrivals are head waves refracted along the cross-fault material contrast. First, the travel time difference between these arrivals and secondary phases identified as direct P waves scales linearly with the source-receiver distance. Second, these arrivals have the emergent wave character associated in theory and practice with refracted head waves instead of the sharp first breaks associated with direct P arrivals. Third, the first motion polarities of the emergent arrivals are reversed from those of the direct P waves as predicted by the theory of fault zone head waves for slip on the San Andreas fault. The presence of fault zone head waves in local seismic network data may help account for scatter in earthquake locations and source mechanisms. The fault zone head waves indicate that the velocity contrast across the San Andreas fault near Parkfield is approximately 4 percent. Further studies of these waves may provide a way of assessing changes in the physical state of the fault system.

  13. San andreas fault zone head waves near parkfield, california.

    PubMed

    Ben-Zion, Y; Malin, P

    1991-03-29

    Microearthquake seismograms from the borehole seismic network on the San Andreas fault near Parkfield, California, provide three lines of evidence that first P arrivals are "head" waves refracted along the cross-fault material contrast. First, the travel time difference between these arrivals and secondary phases identified as direct P waves scales linearly with the source-receiver distance. Second, these arrivals have the emergent wave character associated in theory and practice with refracted head waves instead of the sharp first breaks associated with direct P arrivals. Third, the first motion polarities of the emergent arrivals are reversed from those of the direct P waves as predicted by the theory of fault zone head waves for slip on the San Andreas fault. The presence of fault zone head waves in local seismic network data may help account for scatter in earthquake locations and source mechanisms. The fault zone head waves indicate that the velocity contrast across the San Andreas fault near Parkfield is approximately 4 percent. Further studies of these waves may provide a way of assessing changes in the physical state of the fault system. PMID:17793143

  14. 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.

  15. 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.

  16. Measuring fault tolerance with the FTAPE fault injection tool

    NASA Astrophysics Data System (ADS)

    Tsai, Timothy K.; Iyer, Ravishankar K.

    1995-05-01

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

  17. Syn-thrusting polygonal normal faults exposed in the hinge of the Cingoli anticline, northern Apennines, Italy

    NASA Astrophysics Data System (ADS)

    Petracchini, Lorenzo; Antonellini, Marco; Billi, Andrea; Scrocca, Davide

    2015-11-01

    The Cingoli arcuate anticline is part of the Apennines fold-thrust belt in Italy. The anticline involves sedimentary carbonate strata generally affected by syn-thrusting contractional structures such as bed-normal pressure solution seams, folds, and reverse faults. An exception is constituted by an outcrop in the anticline hinge, where sub-horizontal carbonate and chert beds are affected by joints and intraformational short normal faults. These faults are poorly-systematic and conceivably polygonal in map view. They cut through the carbonate beds while usually stop against the chert layers that are bent and extended along the faults themselves. At the fault tips, the displacement is generally transferred, via a lateral step, to an adjacent similar fault segment. The fault surfaces are often characterized by slickolites, greenish clayey residue, and micro-breccias including chert and carbonate clasts. Fault displacement is partly or largely accommodated by pressure solution. The faults, in effect, are usually accompanied by bed-parallel pressure solution seams in the two contractional quadrants located at the present or past fault tips. The pressure solution features fade away departing from the faults. This evidence and others are analytically explained with fault tip stress distributions. The faults are interpreted as polygonal normal faults syn-tectonically (syn-thrusting) nucleated in response to multi-directional stretching processes occurred at the Cingoli triple-folded anticline extrados. The faults then grew through a four-stage process: (1. stop) the faults stopped at the competent chert beds; (2. shrink) faulting produced shrinkage (pressure solution) of carbonate beds at the fault compressive tips; (3. shrink and step) the faults stepped laterally at the competent chert beds; (4. shatter) the chert beds were shattered along the fault surfaces. The case presented constitutes the first reported one of syn-thrusting non-diagenetic polygonal normal faults.

  18. Dynamic rupture activation of backthrust fault branching

    NASA Astrophysics Data System (ADS)

    Xu, Shiqing; Fukuyama, Eiichi; Ben-Zion, Yehuda; Ampuero, Jean-Paul

    2015-03-01

    We perform dynamic rupture simulations to investigate the possible reactivation of backthrust branches triggered by ruptures along a main thrust fault. Simulations with slip-weakening fault friction and uniform initial stress show that fast propagation speed or long propagation distance of the main rupture promotes reactivation of backthrust over a range of branch angles. The latter condition may occur separately from the former if rupture speed is limited by an increasing slip-weakening distance towards the junction direction. The results suggest a trade-off between the amplitude and duration of the dynamic stress near the main rupture front for backthrust reactivation. Termination of the main rupture by a barrier can provide enhanced loading amplitude and duration along a backthrust rooted near the barrier, facilitating its reactivation especially with a high frictional resistance. The free surface and depth-dependent initial stress can have several additional effects. The sign of the triggered motion along the backthrust can be reversed from thrust to normal if a deeply nucleated main rupture breaks the free surface, while it is preserved as thrust if the main rupture is terminated by a barrier at depth. The numerical results are discussed in relation to several recent megathrust earthquakes in Sumatra, Chile, and Japan, and related topics such as branch feedbacks to the main fault. The dynamic view on backthrust fault branching provided by the study fills a gap not covered by quasi-static models or observations. A specific examined case of antithetic fault branching may be useful for indicating a barrier-like behavior along the main fault.

  19. OpenStudio - Fault Modeling

    2014-09-19

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

  20. Cable-fault locator

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

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

  1. 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.

  2. 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

  3. High-resolution mapping of two large-scale transpressional fault zones in the California Continental Borderland: Santa Cruz-Catalina Ridge and Ferrelo faults

    NASA Astrophysics Data System (ADS)

    Legg, Mark R.; Kohler, Monica D.; Shintaku, Natsumi; Weeraratne, Dayanthie S.

    2015-05-01

    New mapping of two active transpressional fault zones in the California Continental Borderland, the Santa Cruz-Catalina Ridge fault and the Ferrelo fault, was carried out to characterize their geometries, using over 4500 line-km of new multibeam bathymetry data collected in 2010 combined with existing data. Faults identified from seafloor morphology were verified in the subsurface using existing seismic reflection data including single-channel and multichannel seismic profiles compiled over the past three decades. The two fault systems are parallel and are capable of large lateral offsets and reverse slip during earthquakes. The geometry of the fault systems shows evidence of multiple segments that could experience throughgoing rupture over distances exceeding 100 km. Published earthquake hypocenters from regional seismicity studies further define the lateral and depth extent of the historic fault ruptures. Historical and recent focal mechanisms obtained from first-motion and moment tensor studies confirm regional strain partitioning dominated by right slip on major throughgoing faults with reverse-oblique mechanisms on adjacent structures. Transpression on west and northwest trending structures persists as far as 270 km south of the Transverse Ranges; extension persists in the southern Borderland. A logjam model describes the tectonic evolution of crustal blocks bounded by strike-slip and reverse faults which are restrained from northwest displacement by the Transverse Ranges and the southern San Andreas fault big bend. Because of their potential for dip-slip rupture, the faults may also be capable of generating local tsunamis that would impact Southern California coastlines, including populated regions in the Channel Islands.

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

    NASA Astrophysics Data System (ADS)

    Nakata, T.; Kumamoto, T.

    2004-12-01

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

  5. 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

  6. Fault reactivation control on normal fault growth: an experimental study

    NASA Astrophysics Data System (ADS)

    Bellahsen, Nicolas; Daniel, Jean Marc

    2005-04-01

    Field studies frequently emphasize how fault reactivation is involved in the deformation of the upper crust. However, this phenomenon is generally neglected (except in inversion models) in analogue and numerical models performed to study fault network growth. Using sand/silicon analogue models, we show how pre-existing discontinuities can control the geometry and evolution of a younger fault network. The models show that the reactivation of pre-existing discontinuities and their orientation control: (i) the evolution of the main fault orientation distribution through time, (ii) the geometry of relay fault zones, (iii) the geometry of small scale faulting, and (iv) the geometry and location of fault-controlled basins and depocenters. These results are in good agreement with natural fault networks observed in both the Gulf of Suez and Lake Tanganyika. They demonstrate that heterogeneities such as pre-existing faults should be included in models designed to understand the behavior and the tectonic evolution of sedimentary basins.

  7. Fault geometry and slip distribution of the 1999 Chi-Chi, Taiwan Earthquake imaged from inversion of GPS data

    NASA Astrophysics Data System (ADS)

    Johnson, Kaj M.; Hsu, Ya-Ju; Segall, Paul; Yu, Shui-Beih

    GPS measurements of coseismic displacements from the 1999, Chi-Chi, Taiwan earthquake are modeled using elastic dislocation theory. We find that a single fault plane cannot fit the data, but rather a curved fault surface consisting of multiple segments dipping 20-25° best fits the observations. The model fault exhibits reverse and left-lateral slip on a 75 km long N-S trending segment and reverse and right-lateral slip on a 25 km E-W trending segment at the northern end of the rupture. The 21° dipping E-W segment is inconsistent with previous interpretations of high angle tear faulting.

  8. Previously unrecognized now-inactive strand of the North Anatolian fault in the Thrace basin

    SciTech Connect

    Perincek, D. )

    1988-08-01

    The North Anatolian fault is a major 1,200 km-long transform fault bounding the Anatolian plate to the north. It formed in late middle Miocene time as a broad shear zone with a number of strands splaying westward in a horsetail fashion. Later, movement became localized along the stem, and the southerly and northerly splays became inactive. One such right-lateral, now-inactive splay is the west-northwest-striking Thrace strike-slip fault system, consisting of three subparallel strike-slip faults. From north to south these are the Kirklareli, Lueleburgaz, and Babaeski fault zones, extending {plus minus} 130 km along the strike. The Thrace fault zone probably connected with the presently active northern strand of the North Anatolian fault in the Sea of Marmara in the southeast and may have joined the Plovdiv graben zone in Bulgaria in the northwest. The Thrace basin in which the Thrace fault system is located, is Cenozoic with a sedimentary basin fill from middle Eocene to Pliocene. The Thrace fault system formed in pre-Pliocene time and had become inactive by the Pliocene. Strike-slip fault zones with normal and reverse separation are detected by seismic reflection profiles and subsurface data. Releasing bend extensional structures (e.g., near the town of Lueleburgaz) and restraining bend compressional structures (near Vakiflar-1 well) are abundant on the fault zones. Umurca and Hamitabad fields are en echelon structures on the Lueleburgaz fault zone. The Thrace strike-slip fault system has itself a horsetail shape, the various strands of which become younger southward. The entire system died before the Pliocene, and motion on the North Anatolian fault zone began to be accommodated in the Sea of Marmara region. Thus the Thrace fault system represents the oldest strand of the North Anatolian fault in the west.

  9. ERI investigation of fluid flow in the Nacimiento Fault, New Mexico

    NASA Astrophysics Data System (ADS)

    Halihan, T.; Crossey, L. J.; Karlstrom, K. E.; Cron, B. R.

    2011-12-01

    The Nacimiento Fault is a Laramide top-west reverse fault at the eastern edge of the Colorado Plateau. The fault is being reactivated as a normal fault related to extension in the Rio Grande rift as documented by offset travertine deposits. This study explores the link between faulting and fluid circulation along a southern extension of the Nacimiento fault in the San Ysidro area. This area contains a unique set of travertine-depositing mound springs that are aligned on the N-S fault in the core of the Tierra Amarilla anticline (TA). Helium and carbon isotopic data indicate deep fluid connections in the system. Stable isotope analysis of the waters suggests that these warm springs have a component perhaps related to flow from the distal Valles Caldera hydrothermal system with fluid transport along extensional faults. These springs are still depositing modern travertine, but some extinct mounds are estimated as old as 270 ka. Six electrical resistivity imaging (ERI) lines were laid out parallel and perpendicular to the trace of the fault to image the subsurface geometry and potential fluid pathways of the Nacimiento fault at three locations with depths of investigation of approximately 100 meters. Bulk resistivity estimates ranged from 0.3 to 8600 ohm-meters. Fault perpendicular lines confirm the fault to be steeply east dipping and hence a normal reactivation of the Laramide reverse fault. ERI and fluid chemistry data indicate upwelling of relatively fresh (more resistive) water along the fault zone itself and symmetrical 100-meter scale electrically conductive features on either side of the fault. These patterns are interpreted to represent groundwater convection in the Triassic Aqua Zarca sandstone aquifer. Fault-parallel lines indicate complex fault-parallel flow and spacing of vent sources at mound springs. The ERI data also provide estimates for the thickness and distribution of travertine deposits. Implications for aquifers in the northern New Mexico region

  10. Volcano instability induced by strike-slip faulting

    NASA Astrophysics Data System (ADS)

    Lagmay, A. M. F.; van Wyk de Vries, B.; Kerle, N.; Pyle, D. M.

    2000-09-01

    Analogue sand cone experiments were conducted to study instability generated on volcanic cones by basal strike-slip movement. The results of the analogue models demonstrate that edifice instability may be generated when strike-slip faults underlying a volcano move as a result of tectonic adjustment. This instability occurs on flanks of the volcano above the strike-slip shear. On the surface of the volcano this appears as a pair of sigmoids composed of one reverse and one normal fault. In the interior of the cone the faults form a flower structure. Two destabilised regions are created on the cone flanks between the traces of the sigmoidal faults. Bulging, intense fracturing and landsliding characterise these unstable flanks. Additional analogue experiments conducted to model magmatic intrusion show that fractures and faults developed within the volcanic cone due to basal strike-slip motions strongly control the path of the intruding magma. Intrusion is diverted towards the areas where previous development of reverse and normal faults have occurred, thus causing further instability. We compare our model results to two examples of volcanoes on strike-slip faults: Iriga volcano (Philippines), which underwent non-magmatic collapse, and Mount St. Helens (USA), where a cryptodome was emplaced prior to failure. In the analogue and natural examples, the direction of collapse takes place roughly parallel to the orientation of the underlying shear. The model presented proposes one mechanism for strike-parallel breaching of volcanoes, recently recognised as a common failure direction of volcanoes found in regions with transcurrent and transtensional deformation. The recognition of the effect of basal shearing on volcano stability enables prediction of the likely direction of eventual flank failure in volcanoes overlying strike-slip faults.

  11. Imaging quasi-vertical geological faults with earthquake data

    NASA Astrophysics Data System (ADS)

    Zheglova, P.; McLaughlin, J. R.; Roecker, S. W.; Yoon, J. R.; Renzi, D.

    2012-06-01

    We present a method for imaging quasi-vertically dipping faults with surface records of reflected P waves from small earthquakes. Faults are boundaries between geological structures, such as tectonic plates, and are located in earthquake active regions such as Parkfield, California. The high degree of seismic activity enables the use of multiple seismic recordings in our fault identification algorithm. Major challenges occur because of the quasi-vertical orientation of the fault and the fact that the wave reflected by the fault and recorded by the surface receivers is not well modelled by the direct arrival of the propagating wave generated by the earthquake source. Our method uses the 2-D acoustic wave equation as the model for P-wave propagation. We assume that an approximate wave speed map on the reflection side of the fault is available and the source locations are known, for example, from traveltime tomography. We also assume that the source time function is known. The new features of our method arise because earthquake sources are located very close to the fault. This has two implications: (1) the direct arrival and the reflected wave arrive almost simultaneously, so that it is impossible to separate them on a seismogram using standard techniques, and (2) most of the reflections occur above the critical angle which introduces a distortion in the reflected wave. To overcome these difficulties we use a modelled incident wave to (1) remove the direct arrival from the data, and (2) remove the post-critical distortion from the reflected wave. We justify the distortion removal using the leading-order term of an asymptotic expansion, and an optimization procedure. To complete our algorithm we utilize some features of reverse time migration: (1) the use of full acoustic wave equation for modelling and backpropagation, and (2) zero-lag correlation of the backpropagated time reversed reflected and incident fields. We present numerical examples of fault reconstructions

  12. Porosity and permeability evolution of clay faults: in situ experiments

    NASA Astrophysics Data System (ADS)

    Henry, P.; Guglielmi, Y.; Seguy, S.; Lefevre, M.; Ghani, I.; Gent, G.; Castilla, R.; Gout, C.; Dick, P.; Nussbaum, C.; Durand, J.

    2015-12-01

    Fault models associating low permeability cores with high permeability damage zones are widely accepted, however, constitutive laws relating permeability with fault structure, stress, and strain remain poorly constrained. We here present preliminary results of hydromechanical experiments performed at the 10 m scale in fault zones in Toarcian and Aalenian black shale formations. Intact formations have a very low permeability (10-19 to 10-22 m2). One case (in IRSN's Tournemire Underground Research Laboratory) displays a porosity increase in and around the fault core and abundant veins and calcite cemented small faults in the damage zone. The other case (Mont Terri Swisstopo Underground Research Laboratory) displays a porosity decrease in the fault core zone and few veins. However, under the present stress state, the static permeability of the fractured zones at both locations is higher than that of the intact formation by up to 3 orders of magnitude. During borehole pressurization tests three regimes of permeability variations are observed. (1) Fracture permeability first increases progressively as a function of fluid pressure (2) When a threshold is reached, permeability further increases by 100 or more, but strain as well as permeability variations remain in most part reversible. (3) When a steady pressure is maintained in the injection borehole (from 20 minutes to several days) flow rate tends to decrease with time. These results show that high transient permeability may locally occur in a fault zone under conditions when most of the deformation is reversible, opening the possibility of transient fluid migration decoupled from slip along faults that are not favorably oriented. However, during one test, more than 1 mm of irreversible slip occurred along one of the main interfaces, associated with a sudden increase in flow rate (from 11 to more than 40 l/min). This suggests that when slip occurs, it could result in permeability variations that may remain difficult

  13. Geophysical investigations of the Stuoragurra postglacial fault, Finnmark, northern Norway

    NASA Astrophysics Data System (ADS)

    Olesen, Odleiv; Henkel, Herbert; Lile, Ole Bernt; Mauring, Eirik; Rønning, Jan Steinar

    1992-08-01

    Processed images of aeromagnetic, gravimetric and topographical data and geological maps combined with VLF ground measurements have been interpreted in mapping the main fault structures along the Mierujav'ri-Sværholt Fault Zone (MSFZ) in Finnmark, northern Norway. The 230 km long MSFZ is situated in the extensive Proterozoic terrain of Finnmark. Proterozoic albite diabases, which cause characteristic magnetic anomalies in the Masi area, have intruded along the MSFZ. A system of duplexes can be delineated along the MSFZ from the geophysical images. These interpretations have been followed up in the till-covered area with electromagnetic measurements and confirm the existence of the faults interpreted from the geophysical images. The postglacial Stuoragurra Fault (SF) lies within the MSFZ. It is a southeasterly dipping reverse fault and can be traced fairly continuously for 80 km in the Masi-Iešjav'ri area. Detailed geophysical investigations and drilling have been carried out in the Fidnajåkka area 10 km to the south of Masi. A ca. 1 m thick layer of fault gouge detected in the drillholes is thought to represent the actual fault surface. Resistivity measurements reveal low-resistivity zones in the hanging-wall block as well as in the foot-wall block of the SF. These low-resistivity zones lie within a several hundred metre wide belt and are interpreted to be due to fracturing of the quartzites along the regional MSFZ. Within the Fidnajåkka area, however, the resistivity of the hanging-wall block of the SF is typically lower than in the foot-wall, indicating more intense fracturing in the hanging-wall. Vertical electrical soundings show a low-resistivity layer at depth in the eastern hanging-wall block, which corroborates other evidence that the fault dips to the southeast. The refraction seismic data reveal low seismic velocities along the SF which are interpreted to be caused by faulted and fractured bedrock. Detailed topographical data proved very useful for

  14. Development of Hydrologic Characterization Technology of Fault Zones

    SciTech Connect

    Karasaki, Kenzi; Onishi, Tiemi; Wu, Yu-Shu

    2008-03-31

    Through an extensive literature survey we find that there is very limited amount of work on fault zone hydrology, particularly in the field using borehole testing. The common elements of a fault include a core, and damage zones. The core usually acts as a barrier to the flow across it, whereas the damage zone controls the flow either parallel to the strike or dip of a fault. In most of cases the damage zone isthe one that is controlling the flow in the fault zone and the surroundings. The permeability of damage zone is in the range of two to three orders of magnitude higher than the protolith. The fault core can have permeability up to seven orders of magnitude lower than the damage zone. The fault types (normal, reverse, and strike-slip) by themselves do not appear to be a clear classifier of the hydrology of fault zones. However, there still remains a possibility that other additional geologic attributes and scaling relationships can be used to predict or bracket the range of hydrologic behavior of fault zones. AMT (Audio frequency Magneto Telluric) and seismic reflection techniques are often used to locate faults. Geochemical signatures and temperature distributions are often used to identify flow domains and/or directions. ALSM (Airborne Laser Swath Mapping) or LIDAR (Light Detection and Ranging) method may prove to be a powerful tool for identifying lineaments in place of the traditional photogrammetry. Nonetheless not much work has been done to characterize the hydrologic properties of faults by directly testing them using pump tests. There are some uncertainties involved in analyzing pressure transients of pump tests: both low permeability and high permeability faults exhibit similar pressure responses. A physically based conceptual and numerical model is presented for simulating fluid and heat flow and solute transport through fractured fault zones using a multiple-continuum medium approach. Data from the Horonobe URL site are analyzed to demonstrate the

  15. 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).

  16. Fault connectivity, distributed shortening, and impacts on geologic- geodetic slip rate discrepancies in the central Mojave Desert, California

    NASA Astrophysics Data System (ADS)

    Selander, J.; Oskin, M. E.; Cooke, M. L.; Grette, K.

    2015-12-01

    Understanding off-fault deformation and distribution of displacement rates associated with disconnected strike-slip faults requires a three-dimensional view of fault geometries. We address problems associated with distributed faulting by studying the Mojave segment of the East California Shear Zone (ECSZ), a region dominated by northwest-directed dextral shear along disconnected northwest- southeast striking faults. We use a combination of cross-sectional interpretations, 3D Boundary Element Method (BEM) models, and slip-rate measurements to test new hypothesized fault connections. We find that reverse faulting acts as an important means of slip transfer between strike-slip faults, and show that the impacts of these structural connections on shortening, uplift, strike-slip rates, and off-fault deformation, help to reconcile the overall strain budget across this portion of the ECSZ. In detail, we focus on the Calico and Blackwater faults, which are hypothesized to together represent the longest linked fault system in the Mojave ECSZ, connected by a restraining step at 35°N. Across this restraining step the system displays a pronounced displacement gradient, where dextral offset decreases from ~11.5 to <2 km from south to north. Cross-section interpretations show that ~40% of this displacement is transferred from the Calico fault to the Harper Lake and Blackwater faults via a set of north-dipping thrust ramps. Late Quaternary dextral slip rates follow a similar pattern, where 1.4 +0.8/-0.4 mm/yr of slip along the Calico fault south of 35°N is distributed to the Harper Lake, Blackwater, and Tin Can Alley faults. BEM model results using revised fault geometries for the Mojave ECSZ show areas of uplift consistent with contractional structures, and fault slip-rates that more closely match geologic data. Overall, revised fault connections and addition of off-fault deformation greatly reduces the discrepancy between geodetic and geologic slip rates.

  17. Splay Faults and Associated Mass Transport Deposits in the Manila Accretionary Wedge near Taiwan: Implications for Geohazards

    NASA Astrophysics Data System (ADS)

    Lin, A. T.; Liu, C. S.; Dirgantara, F.

    2015-12-01

    Plate interface megathrusts are major seismogenic faults in subduction zone, capable of generating great earthquakes with widespread submarine landslides and damaging tsunami. Upward branching of megathrusts results in splay faults in the accretionary wedge. Reflection seismic data across the accretionary wedge off southern Taiwan, reveal at least two strands of splay faults as well as multiple stacked mass transport deposits (MTDs) nearby the faults. With the help of sediment coring and age datings in the vicinity of the splay fault, implications for temporal evolution of the mass wasting processes and episodic activities of splay faults are discussed in this paper. Seismic data show two branches of arcward and gently-dipping splay faults with two slope basins lying in the footwall and hangingwall of the faults, respectively. The older and buried splay fault is inactive as the fault tip is covered by up to 1000 m thick sediments in the footwall slope basin, indicating that it ceased to be active around 0.5 Ma ago. Repeated slip of this fault prior to ~0.5 Ma ago may also result in 4 stacked and multiple mass transport deposits (MTDs) of up to 700-m thick found in vicinity of this fault. This fossil splay fault is characterized by reflection polarity similar to that of seafloor, indicative of low water saturation along the fault zone and hence not an active fluid conduit. The younger and overlying splay fault cuts through the seafloor and the emergent fault tip lying at the toe of steep slope (~ 15 degree) with significant slope break. There is also a 500-m horizontal offset, between the buried paleo-seafloor in the footwall and the present-day seafloor on the hangingwall. The reflection polarity of this fault zone is reversed to that of seafloor, indicating fluid rich for this fault patch. These lines of evidence suggest that this young splay fault is an active fault with active fluid circulation along the fault. Our results indicate that the old splay fault

  18. 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.

  19. 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.

  20. 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.

  1. Ius Chasma Fault

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-415, 8 July 2003

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a 'text-book example' of an offset in layered rock caused by a fault. The offset is most easily seen near the upper right of the image. The martian crust is faulted, and the planet has probably experienced 'earthquakes' (or, marsquakes) in the past. This scene is located on the floor of Ius Chasma near 7.8oS, 80.6oW. Sunlight illuminates the scene from the upper left.

  2. 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.

  3. 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.

  4. 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.

  5. Upper Pleistocene - Holocene activity of the Carrascoy Fault (Murcia, SE Spain): preliminary results from paleoseismological research.

    NASA Astrophysics Data System (ADS)

    Martin-Banda, Raquel; Garcia-Mayordomo, Julian; Insua-Arevalo, Juan M.; Salazar, Angel; Rodriguez-Escudero, Emilio; Alvarez-Gomez, Jose A.; Martinez-Diaz, Jose J.; Herrero, Maria J.; Medialdea, Alicia

    2014-05-01

    The Carrascoy Fault is located in the Internal Zones of the Betic Cordillera (Southern Spain). In particular, the Carrascoy Fault is one of the major faults forming the Eastern Betic Shear Zone, the main structure accommodating the convergence between Nubian and Eurasian plates in the westernmost Mediterranean. So far, the Carrascoy Fault has been defined as a left-lateral strike-slip fault. It extends for at least 31 km in a NE-SW trend from the village of Zeneta (Murcia) at its northeastern tip, to the Cañaricos village, controlling the northern edge of the Carrascoy Range and its linkage to the Guadalentin Depression towards the southwest. This is an area of moderate seismic activity, but densely populated, the capital of the region, Murcia, being settled very close to the fault. Hence, the knowledge of the structure and kinematics of the Carrascoy Fault is essential for assessing reliably the seismic hazard of the region. We present a detailed-scale geological and geomorphological map along the fault zone created from a LIDAR DEM combined with fieldwork, and geological and geophysical information. Furthermore, a number of trenches have been dug across the fault at different locations providing insights in the fault most recent activity as well as paleoseismic data. Preliminary results suggest that the Cararscoy Fault has recently changed its kinematic showing a near pure reverse motion. According to this, the fault can be divided into two distinct segments, the eastern one: Zeneta - Fuensanta, and the western one: Fuensanta - Cañaricos, each one having its own characteristic style and geodynamics. Some new active strands of the fault locate at the foot of the very first relief towards the North of the older strand, forming the current southern border of the Guadalentin Depression. These new faults show an increasingly reverse component westwards, so that the Fuensanta - Cañaricos segment is constituted by thrusts, which are blind at its western end

  6. 3D Dynamic Rupture Simulations Across Interacting Faults: the Mw7.0, 2010, Haiti Earthquake

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    The mechanisms controlling rupture propagation between fault segments during an earthquake are key to the hazard posed by fault systems. Rupture initiation on a fault segment sometimes transfers to a larger fault, resulting in a significant event (e.g.i, 2002 M7.9Denali and 2010 M7.1 Darfield earthquakes). In other cases rupture is constrained to the initial segment and does not transfer to nearby faults, resulting in events of moderate magnitude. This is the case of the 1989 M6.9 Loma Prieta and 2010 M7.0 Haiti earthquakes which initiated on reverse faults abutting against a major strike-slip plate boundary fault but did not propagate onto it. Here we investigatethe rupture dynamics of the Haiti earthquake, seeking to understand why rupture propagated across two segments of the Léogâne fault but did not propagate to the adjacenent Enriquillo Plantain Garden Fault, the major 200 km long plate boundary fault cutting through southern Haiti. We use a Finite Element Model to simulate the nucleation and propagation of rupture on the Léogâne fault, varying friction and background stress to determine the parameter set that best explains the observed earthquake sequence. The best-fit simulation is in remarkable agreement with several finite fault inversions and predicts ground displacement in very good agreement with geodetic and geological observations. The two slip patches inferred from finite-fault inversions are explained by the successive rupture of two fault segments oriented favorably with respect to the rupture propagation, while the geometry of the Enriquillo fault did not allow shear stress to reach failure. Although our simulation results replicate well the ground deformation consistent with the geodetic surface observation but convolving the ground motion with the soil amplification from the microzonation study will correctly account for the heterogeneity of the PGA throughout the rupture area.

  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. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  10. Towards Fault Resilient Global Arrays

    SciTech Connect

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

    2007-09-03

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

  11. Structural Analysis of Active North Bozgush Fault Zone (NW Iran)

    NASA Astrophysics Data System (ADS)

    Saber, R.; Isik, V.; Caglayan, A.

    2013-12-01

    NW Iran is one of the seismically active regions between Zagros Thrust Belt at the south and Caucasus at the north. Not only large magnitude historical earthquakes (Ms>7), but also 1987 Bozgush, 1997 Ardebil (Mw 6.1) and 2012 Ahar-Varzagan (Mw 6.4) earthquakes reveal that the region is seismically active. The North Bozgush Fault Zone (NBFZ) in this region has tens of kilometers in length and hundreds of meters in width. The zone has produced some large and destructive earthquakes (1593 M:6.1 and 1883 M:6.2). The NBFZ affects the Cenozoic units and along this zone Eocene units thrusted over Miocene and/or Plio-Quaternary sedimentary units. Together with morphologic features (stream offsets and alluvial fan movements) affecting the young unites reveal that the zone is active. The zone is mainly characterized by strike-slip faults with reverse component and reverse faults. Reverse faults striking N55°-85°E and dip of 40°-50° to the SW while strike-slip faults show right lateral slip with N60°-85°W and N60°-80°E directions. Our structural data analysis in NBFZ indicates that the axis direction of σ2 principal stress is vertical and the stress ratio (R) is 0.12. These results suggest that the tectonic regime along the North Bozgush Fault Zone is transpressive. Obtained other principal stresses (σ1, σ3) results are compatible with stress directions and GPS velocity suggested for NW Iran.

  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

    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.

  14. 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.

  15. 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.

  16. Late quaternary active characteristics and slip-rate of Pingding-Huama Fault, the eastern segment of Guanggaishan-Dieshan Fault zone ( West Qinlin Mountain )

    NASA Astrophysics Data System (ADS)

    Jingxing, Y.; Wenjun, Z.; Daoyang, Y.; Jianzhang, P.; Xingwang, L.; Baiyun, L.

    2012-12-01

    Stretching along the west QinlinShan in the north Tibet, the Guanggaishan-Dieshanfaultis composed of three sub-parallel faults among which the major one is a fault named Pingding-Huama fault. The Pingding-Huama fault can be further defined as a combination of a western segment and an eastern segment separated by Minjiang river at Dangchang. Along the western segment of the Pingding-Huama fault, significant linear characteristics, scars, and fault scarps cutting several alluvial fans can be easily distinguished, indicating that the western segment is active since the late Quatenary and the elapsed time of the last event should be less than 1ka B.P.. We estimated the slip rates of the western segment through geomorphology analysis and dating the age of the top surface of terraces and the deformed strata (OSL, 14C). The results show that its reverse slip rate ranges from 0.69±0.16 to 1.15±0.28mm/a and the sinistral slip rate is 0.51±0.13mm/a. In contrast to the simple structure of the western segment, the eastern segment consists of several sub-parallel faults as well as oblique intersected faults. On all faults of the eastern segment, no sign of recent movement was discovered. Along these faults, the tectonic topography features a sequence of linear valleys in the west and dominant folds in the east. Only striations in bedrock and geomorphology show that the eastern segment was reversely slipping on the whole with sinistral component. In summary, at present the Pingding-Huama fault is active along its western segment while shows very weak deformation along the eastern segment.

  17. 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

  18. Arc-oblique fault systems: their role in the Cenozoic structural evolution and metallogenesis of the Andes of central Chile

    NASA Astrophysics Data System (ADS)

    Piquer, Jose; Berry, Ron F.; Scott, Robert J.; Cooke, David R.

    2016-08-01

    The evolution of the Main Cordillera of Central Chile is characterized by the formation and subsequent inversion of an intra-arc volcano-tectonic basin. The world's largest porphyry Cu-Mo deposits were emplaced during basin inversion. Statistically, the area is dominated by NE- and NW-striking faults, oblique to the N-striking inverted basin-margin faults and to the axis of Cenozoic magmatism. This structural pattern is interpreted to reflect the architecture of the pre-Andean basement. Stratigraphic correlations, syn-extensional deposits and kinematic criteria on fault surfaces show several arc-oblique structures were active as normal faults at different stages of basin evolution. The geometry of syn-tectonic hydrothermal mineral fibers, in turn, demonstrates that most of these structures were reactivated as strike-slip ± reverse faults during the middle Miocene - early Pliocene. Fault reactivation age is constrained by 40Ar/39Ar dating of hydrothermal minerals deposited during fault slip. The abundance and distribution of these minerals indicates fault-controlled hydrothermal fluid flow was widespread during basin inversion. Fault reactivation occurred under a transpressive regime with E- to ENE-directed shortening, and was concentrated around major plutons and hydrothermal centers. At the margins of the former intra-arc basin, deformation was largely accommodated by reverse faulting, whereas in its central part strike-slip faulting was predominant.

  19. New evidence on the state of stress of the san andreas fault system.

    PubMed

    Zoback, M D; Zoback, M L; Mount, V S; Suppe, J; Eaton, J P; Healy, J H; Oppenheimer, D; Reasenberg, P; Jones, L; Raleigh, C B; Wong, I G; Scotti, O; Wentworth, C

    1987-11-20

    Contemporary in situ tectonic stress indicators along the San Andreas fault system in central California show northeast-directed horizontal compression that is nearly perpendicular to the strike of the fault. Such compression explains recent uplift of the Coast Ranges and the numerous active reverse faults and folds that trend nearly parallel to the San Andreas and that are otherwise unexplainable in terms of strike-slip deformation. Fault-normal crustal compression in central California is proposed to result from the extremely low shear strength of the San Andreas and the slightly convergent relative motion between the Pacific and North American plates. Preliminary in situ stress data from the Cajon Pass scientific drill hole (located 3.6 kilometers northeast of the San Andreas in southern California near San Bernardino, California) are also consistent with a weak fault, as they show no right-lateral shear stress at approximately 2-kilometer depth on planes parallel to the San Andreas fault. PMID:17839366

  20. Continuity of the San Andreas Fault at San Gorgonio Pass

    NASA Astrophysics Data System (ADS)

    Carena, S.; Suppe, J.

    2002-12-01

    The San Andreas fault at San Gorgonio Pass does not have a clear surface trace and is considered aseismic. Our findings suggest in fact that the existence of a through-going vertical or near-vertical San Andreas fault between Yucaipa and North Palm Springs is highly unlikely. We mapped over 70 faults in the San Gorgonio Pass-San Bernardino Mountains region using the catalog of 43,500 relocated 1975-1998 earthquakes of Richards-Dinger and Shearer (2000). A clustering algorithm was applied to the relocated earthquakes in order to obtain tighter earthquake clouds and thus better-defined fault surfaces. The earthquakes were then imported into Gocad, a 3D modeling software that allowed us to separate earthquakes into coplanar clusters associated with different faults and fault strands and to fit optimized surfaces to them. We also used the catalog of 13,000 focal mechanisms of Hauksson (2000) to confirm the nature of the mapped faults. We were able to constrain the 3D geometry of the San Andreas fault near San Gorgonio Pass from the 3D geometry of the fault network surrounding it. None of these faults show any displacement due to an hypothetical sub-vertical San Andreas. The San Andreas fault must therefore rotate to much shallower dips, or lose its continuity at depths between 3 and 15 km The most likely configuration is the one where the San Andreas fault merges into the shallow-dipping San Gorgonio Pass thrust W of North Palm Springs. Strike-slip motion is taken up by both the thrust (the slip vector on the N. Palm Springs segment is reverse/right-lateral strike-slip) and by a series of NW striking faults in the footwall of the thrust. The W termination of the most active part of the San Gorgonio Pass thrust coincides with one of these footwall faults at depth, and with the south bend in the San Andreas fault strand N of Banning. This boundary also marks a change in the stress field, with a dominant strike-slip regime to the E (and localized thrusting between San

  1. Reactivated strike slip faults: examples from north Cornwall, UK

    NASA Astrophysics Data System (ADS)

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

    2001-10-01

    Several strike-slip faults at Crackington Haven, UK show evidence of right-lateral movement with tip cracks and dilatational jogs, which have been reactivated by left-lateral strike-slip movement. Evidence for reactivation includes two slickenside striae on a single fault surface, two groups of tip cracks with different orientations and very low displacement gradients or negative (left-lateral) displacements at fault tips. Evidence for the relative age of the two strike-slip movements is (1) the first formed tip cracks associated with right-lateral slip are deformed, whereas the tip cracks formed during left-lateral slip show no deformation; (2) some of the tip cracks associated with right-lateral movement show left-lateral reactivation; and (3) left-lateral displacement is commonly recorded at the tips of dominantly right-lateral faults. The orientation of the tip cracks to the main fault is 30-70° clockwise for right-lateral slip, and 20-40° counter-clockwise for left-lateral slip. The structure formed by this process of strike-slip reactivation is termed a "tree structure" because it is similar to a tree with branches. The angular difference between these two groups of tip cracks could be interpreted as due to different stress distribution (e.g., transtensional/transpressional, near-field or far-field stress), different fracture modes or fractures utilizing pre-existing planes of weakness. Most of the d- x profiles have similar patterns, which show low or negative displacement at the segment fault tips. Although the d- x profiles are complicated by fault segments and reactivation, they provide clear evidence for reactivation. Profiles that experienced two opposite slip movements show various shapes depending on the amount of displacement and the slip sequence. For a larger slip followed by a smaller slip with opposite sense, the profile would be expected to record very low or reverse displacement at fault tips due to late-stage tip propagation. Whereas for a

  2. Late Quaternary slip rate of the Batang Fault and its strain partitioning role in Yushu area, central Tibet

    NASA Astrophysics Data System (ADS)

    Huang, Xuemeng; Du, Yi; He, Zhongtai; Ma, Baoqi; Xie, Furen

    2015-06-01

    The late Quaternary activity of Yushu segment is poorly understood compared with other segments within Ganzi-Yushu Fault system. We focused on the Batang Fault, a major branch fault of the Yushu segment. Interpretation of remote sensing images and field investigations reveals that this fault has a clear geomorphic expression which is characterized by prominent fault escarpment and systematically offset gullies, fluvial terraces and alluvial fans along strike. Morphotectonic mapping, combined with optically stimulated luminescence (OSL) and radiocarbon (14C) data, suggest that the Batang Fault is a late Holocene active left-lateral strike-slip fault, along with some reverse component. The average left-lateral slip rate of this fault is 2-4 mm/yr and vertical slip rate is 0.2-0.6 mm/yr since Late Pleistocene. Comparison with the slip rates of other faults within the Ganzi-Yushu Fault system demonstrates that the Batang Fault partitioned nearly a third of the strike slip deformation within Yushu segment. This study provides insights into the reasons why the Yushu Fault is relatively less active when compared with other segments within Ganzi-Yushu Fault system and is crucial to the seismic hazard assessment in Yushu area especially after the occurrence of 2010 Ms 7.1 Yushu earthquake.

  3. Where Does the Seattle Fault End? Structural Links and Kinematic Implications

    NASA Astrophysics Data System (ADS)

    Anderson, M. L.; Dragovich, J. D.; Blakely, R. J.; Wells, R.; Brocher, T. M.

    2008-12-01

    The Seattle fault is one of several east-trending compressional structures in the Puget Lowland (PL), seemingly at odds with the northeasterly oriented compression along the Juan de Fuca subduction zone. The existence of these faults is thought to be related to the northward movement of a strong Oregon forearc block. A weaker PL block accommodates north-south shortening between Siletzia and the slower-moving Canadian Coast Mountains to the north. The northward movement of the PL requires either the Cascade and Olympic Mountains to move northward and shorten at nearly the same rate as the PL, or the existence of strike-slip accommodation zones bounding the PL. We use results from three study areas along the Seattle fault to constrain its behavior: the westward terminus at the foot of the Olympic Mountains, its central reach near Bainbridge Island and its eastward terminus in the Cascade foothills near Fall City, WA. Geologic map data, trench observations across faults, Lidar topographic scarp observations, seismic reflection profiles and potential field anomalies are integrated to determine fault structure. These data indicate that the Seattle fault extends further east and west than previously thought. This suggests its connection to strike-slip fault zones bounding the east (Rattlesnake Mountain fault zone, right-lateral) and west (Saddle Mountain deformation zone, left-lateral) ends of the fault. Gravity and aeromagnetic anomalies along the Seattle fault are best modeled by a fairly simple, reverse fault (dipping south 35-50 degrees). The strike of the proposed PL-block bounding faults suggests a kinematic explanation for the existence, position and dip of the Seattle fault and other east-striking compressional structures in the region. An analog (clay) model illustrates the growth of both the Seattle uplift and the Kingston arch resulting from these proposed kinematic bounding conditions. The strike-slip faults form a crustal "funnel", narrowing to the north

  4. Seismic imaging of deformation zones associated with normal fault-related folding

    NASA Astrophysics Data System (ADS)

    Lapadat, Alexandru; Imber, Jonathan; Iacopini, David; Hobbs, Richard

    2016-04-01

    Folds associated with normal faulting, which are mainly the result of fault propagation and linkage of normal fault segments, can exhibit complex deformation patterns, with multiple synthetic splay faults, reverse faults and small antithetic Riedel structures accommodating flexure of the beds. Their identification is critical in evaluating connectivity of potential hydrocarbon reservoirs and sealing capacity of faults. Previous research showed that seismic attributes can be successfully used to image complex structures and deformation distribution in submarine thrust folds. We use seismic trace and coherency attributes, a combination of instantaneous phase, tensor discontinuity and semblance attributes to identify deformation structures at the limit of seismic resolution, which accommodate seismic scale folding associated with normal faulting from Inner Moray Firth Basin, offshore Scotland. We identify synthetic splay faults and reverse faults adjacent to the master normal faults, which are localized in areas with highest fold amplitudes. This zone of small scale faulting is the widest in areas with highest fault throw / fold amplitude, or where a bend is present in the main fault surface. We also explore the possibility that changes in elastic properties of the rocks due to deformation can contribute to amplitude reductions in the fault damage zones. We analyse a pre-stack time-migrated 3D seismic data-set, where seismic reflections corresponding to a regionally-continuous and homogeneous carbonate layer display a positive correlation between strain distribution and amplitude variations adjacent to the faults. Seismic amplitude values are homogeneously distributed within the undeformed area of the footwall, with a minimum deviation from a mean amplitude value calculated for each seismic line. Meanwhile, the amplitude dimming zone is more pronounced (negative deviation increases) and widens within the relay zone, where sub-seismic scale faults, which accommodate

  5. 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.

  6. Active faulting on the Wallula fault within the Olympic-Wallowa Lineament (OWL), eastern Washington State

    NASA Astrophysics Data System (ADS)

    Sherrod, B. L.; Lasher, J. P.; Barnett, E. A.

    2013-12-01

    Several studies over the last 40 years focused on a segment of the Wallula fault exposed in a quarry at Finley, Washington. The Wallula fault is important because it is part of the Olympic-Wallowa lineament (OWL), a ~500-km-long topographic and structural lineament extending from Vancouver Island, British Columbia to Walla Walla, Washington that accommodates Basin and Range extension. The origin and nature of the OWL is of interest because it contains potentially active faults that are within 50 km of high-level nuclear waste facilities at the Hanford Site. Mapping in the 1970's and 1980's suggested the Wallula fault did not offset Holocene and late Pleistocene deposits and is therefore inactive. New exposures of the Finley quarry wall studied here suggest otherwise. We map three main packages of rocks and sediments in a ~10 m high quarry exposure. The oldest rocks are very fine grained basalts of the Columbia River Basalt Group (~13.5 Ma). The next youngest deposits include a thin layer of vesicular basalt, white volcaniclastic deposits, colluvium containing clasts of vesicular basalt, and indurated paleosols. A distinct angular unconformity separates these vesicular basalt-bearing units from overlying late Pleistocene flood deposits, two colluvium layers containing angular clasts of basalt, and Holocene tephra-bearing loess. A tephra within the loess likely correlates to nearby outcrops of Mazama ash. We recognize three styles of faults: 1) a near vertical master reverse or oblique fault juxtaposing very fine grained basalt against late Tertiary-Holocene deposits, and marked by a thick (~40 cm) vertical seam of carbonate cemented breccia; 2) subvertical faults that flatten upwards and displace late Tertiary(?) to Quaternary(?) soils, colluvium, and volcaniclastic deposits; and 3) flexural slip faults along bedding planes in folded deposits in the footwall. We infer at least two Holocene earthquakes from the quarry exposure. The first Holocene earthquake deformed

  7. 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.

  8. Surface and subsurface structural analysis of a part of Washita Valley fault zone, southern Oklahoma

    SciTech Connect

    Palladino, D.L.

    1984-04-01

    The Washita Valley fault zone is one of the major northwest-trending structures in southern Oklahoma. This fault system is believed to have originated as a series of normal faults during the formation of the southern Oklahoma aulacogen by late Precambrian or early Cambrian time and to have been reactivated during the Arbuckle orogeny in the Pennsylvanian. Descriptions of movement along the Washita Valley fault zone during Pennsylvanian deformation include numerous interpretations, the most common being left-lateral strike slip with 30-40 mi (50-65 km) of displacement. Structures in the area, however, suggest an alternate model. A detailed field study of small folds, faults, fracture arrays, slickensides, and drainage patterns was conducted along the southeastern half of the Washita Valley fault zone. An attempt has been made to relate these small-scale features to the major structures in the area to determine the orientation of the major compressive stress during deformation and the relative amounts of strike-slip vs. reverse dip-slip movement along the fault zone. Exploration for oil and gas along the Washita Valley fault zone has identified several overturned folds and repeated sections. Field observations in the study area include small drag folds and thrust faults parallel to the trend of the Washita Valley fault zone. The two major anticlines in the area, the Arbuckle and the Tishomingo, are both nearly parallel to the trend of the fault zone. These data suggest a model of deformation involving a large component of reverse dip-slip faulting with major duplication of strata.

  9. Folding and faulting of strain-hardening sedimentary rocks

    USGS Publications Warehouse

    Johnson, A.M.

    1980-01-01

    The question of whether single- or multi-layers of sedimentary rocks will fault or fold when subjected to layer-parallel shortening is investigated by means of the theory of elastic-plastic, strain-hardening materials, which should closely describe the properties of sedimentary rocks at high levels in the Earth's crust. The most attractive feature of the theory is that folding and faulting, intimately related in nature, are different responses of the same idealized material to different conditions. When single-layers of sedimentary rock behave much as strain-hardening materials they are unlikely to fold, rather they tend to fault, because contrasts in elasticity and strength properties of sedimentary rocks are low. Amplifications of folds in such materials are negligible whether contacts between layer and media are bonded or free to slip for single layers of dolomite, limestone, sandstone, or siltstone in media of shale. Multilayers of these same rocks fault rather than fold if contacts are bonded, but they fold readily if contacts between layers are frictionless, or have low yield strengths, for example due to high pore-water pressure. Faults may accompany the folds, occurring where compression is increased in cores of folds. Where there is predominant reverse faulting in sedimentary sequences, there probably were few structural units. ?? 1980.

  10. Structural character of Hosgri fault zone and adjacent areas in offshore central California

    SciTech Connect

    Crouch, J.K.; Bachman, S.B.

    1987-05-01

    The Hosgri fault zone extends from the east-west Transverse Ranges structures near Point Arguello northward for more than 150 km to the offshore area near San Simeon Point. The fault zone is seismically active and consists chiefly of a continuous series of eastside-up thrust and high-angle reverse faults. East of the fault zone, Miocene Monterey and volcanic rocks, along with underlying pre-Miocene strata, have been tightly folded as a result of low-angle imbricate thrust faulting during post-Miocene time. These highly deformed strata have been uplited and truncated along the inner shelf. Immediately west of the Hosgria fault zone, similar Monterey and older rocks, which are less folded, conformably underlie Pliocene and younger basinal strata at structural levels that are generally 1200 to 2000 m deeper than correlative strata east of the Hosgri fault zone. Following its discovery in 1971, the Hosgri fault zone was characterized by subsequent investigators as a northwest-trending fault that was part of the San Andreas system of strike-slip faults, with disagreements on the timing and amount of right-lateral offset along the fault zone. However, modern offshore seismic-reflection data, earthquake focal-mechanism studies, and recently available offshore well information suggest that the Hosgri fault zone is instead a major imbricate thrust zone. Detailed structural analyses along part of the Hosgri fault zone suggest that little, if any, strike-slip offset has occurred along this structural trend since its post-Miocene inception. Nevertheless, the Hosgri fault zone itself can be interpreted to be a product of the larger overall San Andreas transform system in that compression has developed because the San Andreas is not parallel to the Pacific-North American plate motion.

  11. Fault diagnosis of analog circuits

    SciTech Connect

    Bandler, J.W.; Salama, A.E.

    1985-08-01

    In this paper, various fault location techniques in analog networks are described and compared. The emphasis is on the more recent developments in the subject. Four main approaches for fault location are addressed, examined, and illustrated using simple network examples. In particular, we consider the fault dictionary approach, the parameter identification approach, the fault verification approach, and the approximation approach. Theory and algorithms that are associated with these approaches are reviewed and problems of their practical application are identified. Associated with the fault dictionary approach we consider fault dictionary construction techniques, methods of optimum measurement selection, different fault isolation criteria, and efficient fault simulation techniques. Parameter identification techniques that either utilize linear or nonlinear systems of equations to identify all network elements are examined very thoroughly. Under fault verification techniques we discuss node-fault diagnosis, branch-fault diagnosis, subnetwork testability conditions as well as combinatorial techniques, the failure bound technique, and the network decomposition technique. For the approximation approach we consider probabilistic methods and optimization-based methods. The artificial intelligence technique and the different measures of testability are also considered. The main features of the techniques considered are summarized in a comparative table. An extensive, but not exhaustive, bibliography is provided.

  12. Accommodation of compressional inversion in north-western South Island (New Zealand): Old faults versus new?

    NASA Astrophysics Data System (ADS)

    Ghisetti, F. C.; Sibson, R. H.

    2006-11-01

    In the NW South Island, New Zealand, high-angle faults inherited from episodes of Late Cretaceous-Paleocene and Eocene extension have, since the early Miocene, undergone compressional inversion in association with right-lateral shearing and transpression on the Alpine Fault. Active reverse faulting and large historical earthquakes occur along N-S to NNE-SSW trending faults which at the surface dip 45-75° to both the east and west. The faults truncate subparallel folds that deform the Tertiary sequence overlying a composite Paleozoic-Mesozoic crystalline basement. However, the deep geometry of these faults, their penetration into the middle-to-lower crust and their relationship to the Alpine Fault are poorly understood. The tectonic architecture of this compressional inversion province is analysed by reconstructing structural contours at the base of the Oligocene carbonate sequence in the north-west of the South Island. Deformation of the Oligocene carbonate sequence, structural analyses in the field and subsurface data indicate a mixed style of inversion with (1) reactivation of some high-angle normal faults and (2) thrusting on new, moderate-dipping cross-cutting faults that detach slivers of basement and cause flexural folding in the sedimentary cover. These faults may remain blind or concealed beneath cover sequences but are likely to control seismic rupturing in the basement at depths of ˜10-15 km.

  13. Active faults and minor plates in NE Asia

    NASA Astrophysics Data System (ADS)

    Kozhurin, Andrey I.; Zelenin, Egor A.

    2014-05-01

    Stated nearly 40 yr ago the uncertainty with plate boundaries location in NE Asia (Chapman, Solomon, 1976) still remains unresolved. Based on the prepositions that a plate boundary must, first, reveal itself in linear sets of active structures, and, second, be continuous and closed, we have undertaken interpretation of medium-resolution KH-9 Hexagon satellite imageries, mostly in stereoscopic regime, for nearly the entire region of NE Asia. Main findings are as follows. There are two major active fault zones in the region north of the Bering Sea. One of them, the Khatyrka-Vyvenka zone, stretches NE to ENE skirting the Bering Sea from the Kamchatka isthmus to the Navarin Cape. Judging by the kinematics of the Olyutorsky 2006 earthquake fault, the fault zones move both right-laterally and reversely. The second active fault zone, the Lankovaya-Omolon zone, starts close to the NE margin of the Okhotsk Sea and extends NE up to nearly the margin of the Chukcha Sea. The fault zone is mostly right-lateral, with topographically expressed cumulative horizontal offsets amounting to 2.5-2.6 km. There may be a third NE-SW zone between the major two coinciding with the Penzhina Range as several active faults found in the southern termination of the Range indicate. The two active fault zones divide the NE Asia area into two large domains, which both could be parts of the Bering Sea plate internally broken and with uncertain western limit. Another variant implies the Khatyrka-Vyvenka zone as the Bering Sea plate northern limit, and the Lankovaya-Omolon zone as separating an additional minor plate from the North-American plate. The choice is actually not crucial, and more important is that both variants leave the question of where the Bering Sea plate boundary is in Alaska. The Lankovaya-Omolon zone stretches just across the proposed northern boundary of the Okhorsk Sea plate. NW of the zone, there is a prominent left-lateral Ulakhan fault, which is commonly interpreted to be a

  14. 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

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  16. 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.

  17. 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.

  18. 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.

  19. Recent deformation along the offshore Malibu Coast, Dume, and related faults west of Point Dume, southern California

    USGS Publications Warehouse

    Fisher, M.A.; Langenheim, V.E.; Sorlien, C.C.; Dartnell, P.; Sliter, R.W.; Cochrane, G.R.; Wong, F.L.

    2005-01-01

    Offshore faults west of Point Dume, southern California, are part of an important regional fault system that extends for about 206 km, from near the city of Los Angeles westward along the south flank of the Santa Monica Mountains and through the northern Channel Islands. This boundary fault system separates the western Transverse Ranges, on the north, from the California Continental Borderland, on the south. Previous research showed that the fault system includes many active fault strands; consequently, the entire system is considered a serious potential earthquake hazard to nearby Los Angeles. We present an integrated analysis of multichannel seismic- and high-resolution seismic-reflection data and multibeam-bathymetric information to focus on the central part of the fault system that lies west of Point Dume. We show that some of the main offshore faults have cumulative displacements of 3-5 km, and many faults are currently active because they deform the seafloor or very shallow sediment layers. The main offshore fault is the Dume fault, a large north-dipping reverse fault. In the eastern part of the study area, this fault offsets the seafloor, showing Holocene displacement. Onshore, the Malibu Coast fault dips steeply north, is active, and shows left-oblique slip. The probable offshore extension of this fault is a large fault that dips steeply in its upper part but flattens at depth. High-resolution seismic data show that this fault deforms shallow sediment making up the Hueneme fan complex, indicating Holocene activity. A structure near Sycamore knoll strikes transversely to the main faults and could be important to the analysis of the regional earthquake hazard because the structure might form a boundary between earthquake-rupture segments.

  20. 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.

  1. Novel designs of nanometric parity preserving reversible compressor

    NASA Astrophysics Data System (ADS)

    Shoaei, Soghra; Haghparast, Majid

    2014-08-01

    Reversible logic is a new field of study that has applications in optical information processing, low power CMOS design, DNA computing, bioinformatics, and nanotechnology. Low power consumption is a basic issue in VLSI circuits today. To prevent the distribution of errors in the quantum circuit, the reversible logic gates must be converted into fault-tolerant quantum operations. Parity preserving is used to realize fault tolerant in this circuits. This paper proposes a new parity preserving reversible gate. We named it NPPG gate. The most significant aspect of the NPPG gate is that it can be used to produce parity preserving reversible full adder circuit. The proposed parity preserving reversible full adder using NPPG gate is more efficient than the existing designs in term of quantum cost and it is optimized in terms of number of constant inputs and garbage outputs. Compressors are of importance in VLSI and digital signal processing applications. Effective VLSI compressors reduce the impact of carry propagation of arithmetic operations. They are built from the full adder blocks. We also proposed three new approaches of parity preservation reversible 4:2 compressor circuits. The third design is better than the previous two in terms of evaluation parameters. The important contributions have been made in the literature toward the design of reversible 4:2 compressor circuits; however, there are not efforts toward the design of parity preservation reversible 4:2 compressor circuits. All the scales are in the nanometric criteria.

  2. Dynamic faulting on a conjugate fault system detected by near-fault tilt measurements

    NASA Astrophysics Data System (ADS)

    Fukuyama, Eiichi

    2015-03-01

    There have been reports of conjugate faults that have ruptured during earthquakes. However, it is still unclear whether or not these conjugate faults ruptured coseismically during earthquakes. In this paper, we investigated near-fault ground tilt motions observed at the IWTH25 station during the 2008 Iwate-Miyagi Nairiku earthquake ( M w 6.9). Since near-fault tilt motion is very sensitive to the fault geometry on which the slip occurs during an earthquake, these data make it possible to distinguish between the main fault rupture and a rupture on the conjugate fault. We examined several fault models that have already been proposed and confirmed that only the models with a conjugated fault could explain the tilt data observed at IWTH25. The results support the existence of simultaneous conjugate faulting during the main rupture. This will contribute to the understanding of earthquake rupture dynamics because the conjugate rupture releases the same shear strain as that released on the main fault, and thus it has been considered quite difficult for both ruptures to accelerate simultaneously.

  3. Late Cenozoic strike-slip faulting in the NE Mojave Block: Deformation at the southwest boundary of the Walker Lane belt

    SciTech Connect

    Schermer, E.R. . Geology Dept.)

    1993-04-01

    New structural and stratigraphy data from the NE Mojave Block (NEMB) establish the timing and style of Cenozoic deformation south of the Garlock fault and west of the Avawatz Mts. Unlike adjacent areas, most of the NEMB did not undergo early-mid Miocene extension. Major fault zones strike EW; offset markers and small-scale shear criteria indicate left-lateral strike slip with a small reverse component. Lateral offsets average ca. 1--6 km and vertical offset is locally >200m. Pre-Tertiary markers indicate minimum cumulative sinistral shear of ca. 15 km in the area between the Garlock and Coyote Lake faults. Tertiary strata are deformed together with the older rocks. Along the Ft. Irwin fault, alluvial fan deposits interpreted to be <11Ma appear to be displaced as much as Mesozoic igneous rocks. EW sinistral faults S. of the Garlock fault cut unconsolidated Quaternary deposits; geomorphologic features and trench exposures along segments of the McLean Lake fault and the Tiefort Mt. fault suggest Late Quaternary activity. The EW faults do not cut modern drainages and are not seismically active. NW-striking faults are largely absent within the NEMB; the largest faults bound the domain of EW-striking faults. Offset of Cretaceous and Miocene rocks suggests the W boundary (Goldstone Lake fault) has <2km right separation. Along the E boundary (Soda-Avawatz fault zone), the presence of distinctive clasts in mid-late Miocene conglomerates west of the Avawatz Mts. supports the suggestion of Brady (1984) of ca. 20 km dextral displacement. Other NW-striking faults are cut by EW faults, have unknown or minor dextral displacement (Desert King Spring Fault, Garlic Spring fault) or are low- to moderate-angle left-oblique thrust faults (Red Pass Lake fault zone).

  4. Seismic reflection images of shallow faulting, northernmost Mississippi embayment, north of the New Madrid seismic zone

    USGS Publications Warehouse

    McBride, J.H.; Nelson, W.J.

    2001-01-01

    High-resolution seismic reflection surveys document tectonic faults that displace Pleistocene and older strata just beyond the northeast termination of the New Madrid seismic zone, at the northernmost extent of the Mississippi embayment. These faults, which are part of the Fluorspar Area fault complex in southeastern Illinois, are directly in line with the northeast-trending seismic zone. The reflection data were acquired using an elastic weight-drop source recorded to 500 msec by a 48-geophone array (24-fold) with a 10-ft (??3.0m) station interval. Recognizable reflections were recorded to about 200 msec (100-150 m). The effects of multiple reflections, numerous diffractions, low apparent velocity (i.e., steeply dipping) noise, and the relatively low-frequency content of the recorded signal provided challenges for data processing and interpreting subtle fault offsets. Data processing steps that were critical to the detection of faults included residual statics, post-stack migration, deconvolution, and noise-reduction filtering. Seismic migration was crucial for detecting and mitigating complex fault-related diffraction patterns, which produced an apparent 'folding' of reflectors on unmigrated sections. Detected individual offsets of shallow reflectors range from 5 to 10 m for the top of Paleozoic bedrock and younger strata. The migrated sections generally indicate vertical to steeply dipping normal and reverse faults, which in places outline small horsts and/or grabens. Tilting or folding of stratal reflectors associated with faulting is also locally observed. At one site, the observed faulting is superimposed over a prominent antiformal structure, which may itself be a product of the Quaternary deformation that produced the steep normal and reverse faults. Our results suggest that faulting of the Paleozoic bedrock and younger sediments of the northern Mississippi embayment is more pervasive and less localized than previously thought.

  5. Cenozoic right-lateral wrench tectonics in the Western Pyrenees (Spain): The Ubierna Fault System

    NASA Astrophysics Data System (ADS)

    Tavani, S.; Quintà, A.; Granado, P.

    2011-08-01

    A study of macro and mesostructural deformation patterns of the southern margin of the Cantabrian area (Western Pyrenees, Spain) has revealed a complex Cenozoic tectonic framework. Right-lateral tectonics reactivated inherited WNW-ESE striking faults, which developed during Late Paleozoic and Early Triassic events, and Late Jurassic to Early Cretaceous main rifting stage. The Ubierna Fault represents the southern boundary of the Mesozoic basin. During the Oligocene (even Eocene) to present day deformation, this fault and the Ventaniella Fault located to the south in the study area acted as right-lateral slightly transpressive elements forming a 120 km long and 15 km wide overstep area, here named Ubierna Fault System, where the cumulative right-lateral displacement exceeds 15 km. The Cenozoic tectonic framework of the Ubierna Fault System includes reactivation along the WNW-ESE faults, development of negative and, mostly, positive flower structures, branch faults, strike-slip duplexes, and releasing and restraining bends. NE-SW to ENE-WSW striking reverse faults and contractional horsetail terminations, and NNW-SSE striking normal faults and joints are produced by the WNW-ESE right-lateral strike-slip motion. The extensional elements are well developed and deformation progression implied their incorporation in the strike-slip system as right-lateral faults (forming part of strike-slip duplexes). The abundance of flower structures striking WNW-ESE and paralleling the main strike-slip faults, together with the overall uplift of the overstep area, testifies for a slight compressional component. At a regional scale, the Ubierna Fault System represents the most prominent element of a Cenozoic transpressional belt, which incorporates the western portion of the Basque-Cantabrian Basin and the Asturian Massif area. Lateral transition between this transpressive belt and the dip-slip belt located to the east, occurs across an area experiencing along strike-shortening, which

  6. Source Fault and Rupture Process of the 2006 Yogyakarta Earthquake

    NASA Astrophysics Data System (ADS)

    Kawazoe, Y.; Koketsu, K.

    2010-12-01

    The Yogyakarta earthquake with a moment magnitude of 6.3 occurred in the central part of Java, Indonesia on 26 May 2006 at 22:54 UTC, causing severe damage to the densely populated area of the Yogyakarta region. About 6,000 people were killed, and 50,000 were injured. At first, the Opak River fault, located along the damage area, was thought to be a possible source fault of the event. However, the aftershock distribution suggests that the source fault is located 10 - 20 km east of the Opak River fault (Walter et al., 2007). This new fault was not known at that time, and its geometry and rupture process is little understood even now. Therefore, to overcome these difficulties, we performed teleseismic body-wave inversions. We chose the stations at epicentral distances between 30°and 100°. We retrieved 24 vertical components of broadband P-wave seismograms for these stations from the Data Management Center of IRIS. In order to perform an inversion for the rupture process, it is necessary to set up the source fault plane in advance. We first determined the focal mechanism using the inversion method of Kikuchi and Kanamori (1991). For calculating theoretical waveforms, we used near-source and near-receiver structures derived from CRUST 2.0. We obtained two different types of mechanism, that are left-lateral strike-slip faulting and reverse dip-slip faulting. Based on the obtained focal mechanisms and aftershock distribution, a fault plane is set up as follows: strike= 40°,dip= 85°,length =28km, width =20km , depth of rupture initiation point = 10km. We placed 7×5 grid points with a spacing of 4 km. We then inverted the waveforms for a spatio-temporal distribution of slip on this fault plane (Kikuchi and Kanamori,2003). In the inversion result, we obtained a total seismic moment Mo = 3.8×1013 Nm (Mw = 6.3), rupture front velocity = 2.5 km/s, rupture duration = 10 s, maximum slip = 0.34 m. The resultant slip distribution has two asperities (areas of large slip

  7. 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

  8. 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.

  9. Cyclical Fault Permeability in the Lower Seismogenic Zone: Geological Evidence

    NASA Astrophysics Data System (ADS)

    Sibson, R. H.

    2005-12-01

    Syntectonic hydrothermal veining is widespread in ancient fault zones exhibiting mixed brittle-ductile behavior that are exhumed from subgreenschist to greenschist environments. The hydrothermal material (predominantly quartz ± carbonate) commonly occurs as fault-veins developed along principal slip surfaces, with textures recording intermittent deposition, sometimes in the form of repeated episodes of brecciation and recementation. Systematic sets of extension veins with histories of incremental dilation often occur in adjacent wallrocks. Conspicuous for their size and continuity among these fault-hosted vein systems are mesozonal Au-quartz lodes, which are most widespread in Archean granite-greenstone belts but also occur throughout the geological record. Most of these lode gold deposits developed at pressures of 1-5 kbar and temperatures of 200-450°C within the lower continental seismogenic zone. A notable characteristic is their vertical continuity: many `ribbon-texture' fault veins with thicknesses of the order of a meter extend over depth ranges approaching 2 km. The largest lodes are usually hosted by reverse or reverse- oblique fault zones with low finite displacement. Associated flat-lying extension veins in the wallrock may taper away from the shear zones over tens or hundreds of meters, and demonstrate repeated attainment of the ~lithostatic fluid overpressures needed for hydraulic extension fracturing. Where hosted by extensional-transtensional fault systems, lode systems tend to be less well developed. Mesozonal vein systems are inferred to be the product of extreme fault-valve behavior, whereby episodic accumulation of pore-fluid pressure to near-lithostatic values over the interseismic period leads to fault rupture, followed by postseismic discharge of substantial fluid volumes along the freshly permeable rupture zone inducing hydrothermal precipitation that seals the fracture permeability. Aqueous mineralizing fluids were generally low

  10. Along strike applicability of results from the Deep Fault Drilling Project, Alpine Fault, New Zealand

    NASA Astrophysics Data System (ADS)

    Boulton, C. J.; Toy, V. G.; Barth, N. C.; Carpenter, B. M.

    2012-12-01

    similar brown PSZ gouges also occur at localities north and south of Gaunt Creek, from Little Man River to Robinson Creek, an along strike distance of 120 km. Everywhere mapped, brown PSZ gouges form at the contact between Pacific Plate and Australian Plate-derived cataclasites, which, importantly, do not contain smectite. Smectite-bearing gouges are generally absent on shallow dipping dextral-reverse faults at the toes of large thrust sheets, where plate boundary cataclasites overlie Late Quaternary gravels in sharp contact. Our results suggest that PSZ gouges retrieved in the DFDP-1 cores are commonly present on moderately dipping (average orientation 043°/30°SE; Norris and Cooper, 2007) dextral-reverse faults along the central Alpine Fault, and we discuss modes of PSZ formation. References Boulton, C., B.M. Carpenter, V. Toy, and C. Marone (2012). Physical properties of surface outcrop cataclastic fault rocks, Alpine Fault, New Zealand. Geochem. Geophys. Geosyst., 13, doi:10.1029/2011GC003872. Norris, R.J., and A.F. Cooper (2007). The Alpine Fault, New Zealand: Surface Geology and Field Relationships, in A Continental Plate Boundary: Tectonics at South Island, New Zealand, edited by Okaya, D., Stern, T., and F. Davey, American Geophysical Union Monograph Vol 175, Washington, D.C., 159-178.

  11. Holocene tectonics and fault reactivation in the foothills of the north Cascade Mountains, Washington

    USGS Publications Warehouse

    Sherrod, Brian L.; Barnett, Elizabeth; Schermer, Elizabeth; Kelsey, Harvey M.; Hughes, Jonathan; Foit, Franklin F., Jr.; Weaver, Craig S.; Haugerud, Ralph; Hyatt, Tim

    2013-01-01

    We use LiDAR imagery to identify two fault scarps on latest Pleistocene glacial outwash deposits along the North Fork Nooksack River in Whatcom County, Washington (United States). Mapping and paleoseismic investigation of these previously unknown scarps provide constraints on the earthquake history and seismic hazard in the northern Puget Lowland. The Kendall scarp lies along the mapped trace of the Boulder Creek fault, a south-dipping Tertiary normal fault, and the Canyon Creek scarp lies in close proximity to the south-dipping Canyon Creek fault and the south-dipping Glacier Extensional fault. Both scarps are south-side-up, opposite the sense of displacement observed on the nearby bedrock faults. Trenches excavated across these scarps exposed folded and faulted late Quaternary glacial outwash, locally dated between ca. 12 and 13 ka, and Holocene buried soils and scarp colluvium. Reverse and oblique faulting of the soils and colluvial deposits indicates at least two late Holocene earthquakes, while folding of the glacial outwash prior to formation of the post-glacial soil suggests an earlier Holocene earthquake. Abrupt changes in bed thickness across faults in the Canyon Creek excavation suggest a lateral component of slip. Sediments in a wetland adjacent to the Kendall scarp record three pond-forming episodes during the Holocene—we infer that surface ruptures on the Boulder Creek fault during past earthquakes temporarily blocked the stream channel and created an ephemeral lake. The Boulder Creek and Canyon Creek faults formed in the early to mid-Tertiary as normal faults and likely lay dormant until reactivated as reverse faults in a new stress regime. The most recent earthquakes—each likely Mw > 6.3 and dating to ca. 8050–7250 calendar years B.P. (cal yr B.P.), 3190–2980 cal. yr B.P., and 910–740 cal. yr B.P.—demonstrate that reverse faulting in the northern Puget Lowland poses a hazard to urban areas between Seattle (Washington) and Vancouver

  12. Reversible Thermoset Adhesives

    NASA Technical Reports Server (NTRS)

    Mac Murray, Benjamin C. (Inventor); Tong, Tat H. (Inventor); Hreha, Richard D. (Inventor)

    2016-01-01

    Embodiments of a reversible thermoset adhesive formed by incorporating thermally-reversible cross-linking units and a method for making the reversible thermoset adhesive are provided. One approach to formulating reversible thermoset adhesives includes incorporating dienes, such as furans, and dienophiles, such as maleimides, into a polymer network as reversible covalent cross-links using Diels Alder cross-link formation between the diene and dienophile. The chemical components may be selected based on their compatibility with adhesive chemistry as well as their ability to undergo controlled, reversible cross-linking chemistry.

  13. Experimental Fault Reactivation on Favourably and Unfavourably Oriented Faults

    NASA Astrophysics Data System (ADS)

    Mitchell, T. M.; Sibson, R. H.; Renner, J.; Toy, V. G.; di Toro, G.; Smith, S. A.

    2010-12-01

    In this study, we introduce work which aims assess the loading of faults to failure under different stress regimes in a triaxial deformation apparatus. We explore experimentally the reshear of an existing fault in various orientations for particular values of (σ1 - σ3) and σ3' for contrasting loading systems - load-strengthening (equivalent to a thrust fault) with σ1' increasing at constant σ3', versus load-weakening (equivalent to a normal fault) with reducing σ3' under constant σ1'. Experiments are conducted on sawcut granite samples with fault angles at a variety of orientations relative to σ1 , ranging from an optimal orientation for reactivation to lockup angles where new faults are formed in preference to reactivating the existing sawcut orientation. Prefailure and postfailure behaviour is compared in terms of damage zone development via monitoring variations in ultrasonic velocity and acoustic emission behaviour. For example, damage surrounding unfavourably oriented faults is significantly higher than that seen around favourably orientated faults due to greater maximum stresses attained prior to unstable slip, which is reflected by the increased acoustic emission activity leading up to failure. In addition, we also experimentally explore the reshear of natural pseudotachylytes (PSTs) from two different fault zones; the Gole Larghe Fault, Adamello, Italy in which the PSTs are in relatively isotropic Tonalite (at lab sample scale) and the Alpine Fault, New Zealand in which the PSTs are in highly anisotropic foliated shist. We test whether PSTs will reshear in both rock types under the right conditions, or whether new fractures in the wall rock will form in preference to reactivating the PST (PST shear strength is higher than that of the host rock). Are PSTs representative of one slip event?

  14. Anatomy of a Complex Fault Zone: Land Seismic Reflection Imaging of the Tacoma Fault Zone, Washington State

    NASA Astrophysics Data System (ADS)

    Pape, K.; Liberty, L. M.; Pratt, T. L.

    2005-12-01

    is underlain by south-dipping, faulted and arched Eocene strata that presumably represent deformation in the hanging wall above a major thrust or reverse fault. The arch appears to broaden to the east, with the faults being less obvious or missing on the eastern profile.

  15. Fault welding by pseudotachylyte generation

    NASA Astrophysics Data System (ADS)

    Mitchell, T. M.; Toy, V. G.; Di Toro, G.; Renner, J.

    2014-12-01

    During earthquakes, frictional melts can localize on slip surfaces and dramatically weaken faults by melt lubrication. Once seismic slip is arrested, the melt cools and solidifies to form pseudotachylyte (PST), the presence of which is commonly used to infer earthquake slip on ancient exhumed faults. Little is known about the effect of solidified melt on the strength of faults directly preceding a subsequent earthquake. We performed triaxial deformation experiments on cores of tonalite (Gole Larghe fault zone, N. Italy) and mylonite (Alpine fault, New Zealand) in order to assess the strength of PST bearing faults in the lab. Three types of sample were prepared for each rock type; intact, sawcut and PST bearing, and were cored so that the sawcut, PST and foliation planes were orientated at 35° to the length of the core and direction of σ1, i.e., a favorable orientation for reactivation. This choice of samples allowed us to compare the strength of 'pre-earthquake' fault (sawcut) to a 'post-earthquake' fault with solidified frictional melt, and assess their strength relative to intact samples. Our results show that PST veins effectively weld fault surfaces together, allowing previously faulted rocks to regain cohesive strengths comparable to that of an intact rock. Shearing of the PST is not favored, but subsequent failure and slip is accommodated on new faults nucleating at other zones of weakness. Thus, the mechanism of coseismic weakening by melt lubrication does not necessarily facilitate long-term interseismic deformation localization, at least at the scale of these experiments. In natural fault zones, PSTs are often found distributed over multiple adjacent fault planes or other zones of weakness such as foliation planes. We also modeled the temperature distribution in and around a PST using an approximation for cooling of a thin, infinite sheet by conduction perpendicular to its margins at ambient temperatures commensurate with the depth of PST formation

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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...

  3. 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...

  4. 20 CFR 404.507 - Fault.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

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

  5. 20 CFR 404.507 - Fault.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

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

  6. Midcontinent U.S. fault and fold zones: A legacy of Proterozoic intracratonic extensional tectonism?

    NASA Astrophysics Data System (ADS)

    Marshak, Stephen; Paulsen, Timothy

    1996-02-01

    The U.S. continental interior (midcontinent) contains numerous fault and fold zones. Seismic and drilling data indicate that some of these zones first formed as Proterozoic-Eocambrian rift faults, but the origin of most remains enigmatic. We propose that the enigmatic fault and fold zones also began as Proterozoic-Eocambrian normal faults. We base our hypothesis on the following: (1) enigmatic zones parallel known rifts, (2) the structural style of enigmatic zones mirrors the structural style of known rifts, (3) the map pattern of some enigmatic zones (e.g., the La Salle deformation belt of Illinois) resembles the map pattern of contemporary rifts, and (4) it is easier to rupture an intact craton by normal faulting than by reverse or strike-slip faulting. These zones, along with known rifts, represent the legacy of widespread extensional tectonism that brittlely broke up the craton into fault-bounded blocks prior to deposition of Phanerozoic platform cover. Once formed, midcontinent fault and fold zones remained weak, allowing cratonic blocks to jostle relative to one another during the Phanerozoic, thereby inverting faults (and creating transpressional or transtensional structural assemblages), localizing seismicity, and channeling (or releasing) ore-generating fluids.

  7. Shallow fault-zone dilatancy recovery after the 2003 Bam earthquake in Iran.

    PubMed

    Fielding, Eric J; Lundgren, Paul R; Bürgmann, Roland; Funning, Gareth J

    2009-03-01

    Earthquakes radiate from slip on discrete faults, but also commonly involve distributed deformation within a broader fault zone, especially near the surface. Variations in rock strain during an earthquake are caused by heterogeneity in the elastic stress before the earthquake, by variable material properties and geometry of the fault zones, and by dynamic processes during the rupture. Stress changes due to the earthquake slip, both dynamic and static, have long been thought to cause dilatancy in the fault zone that recovers after the earthquake. Decreases in the velocity of seismic waves passing through the fault zone due to coseismic dilatancy have been observed followed by postseismic seismic velocity increases during healing. Dilatancy and its recovery have not previously been observed geodetically. Here we use interferometric analysis of synthetic aperture radar images to measure postseismic surface deformation after the 2003 Bam, Iran, earthquake and show reversal of coseismic dilatancy in the shallow fault zone that causes subsidence of the surface. This compaction of the fault zone is directly above the patch of greatest coseismic slip at depth. The dilatancy and compaction probably reflects distributed shear and damage to the material during the earthquake that heals afterwards. Coseismic and postseismic deformation spread through a fault zone volume may resolve the paradox of shallow slip deficits for some strike-slip fault ruptures. PMID:19262670

  8. The Cottage Grove fault system (Illinois Basin): Late Paleozoic transpression along a Precambrian crustal boundary

    USGS Publications Warehouse

    Duchek, A.B.; McBride, J.H.; Nelson, W.J.; Leetaru, H.E.

    2004-01-01

    The Cottage Grove fault system in southern Illinois has long been interpreted as an intracratonic dextral strike-slip fault system. We investigated its structural geometry and kinematics in detail using (1) outcrop data, (2) extensive exposures in underground coal mines, (3) abundant borehole data, and (4) a network of industry seismic reflection profiles, including data reprocessed by us. Structural contour mapping delineates distinct monoclines, broad anticlines, and synclines that express Paleozoic-age deformation associated with strike slip along the fault system. As shown on seismic reflection profiles, prominent near-vertical faults that cut the entire Paleozoic section and basement-cover contact branch upward into outward-splaying, high-angle reverse faults. The master fault, sinuous along strike, is characterized along its length by an elongate anticline, ???3 km wide, that parallels the southern side of the master fault. These features signify that the overall kinematic regime was transpressional. Due to the absence of suitable piercing points, the amount of slip cannot be measured, but is constrained at less than 300 m near the ground surface. The Cottage Grove fault system apparently follows a Precambrian terrane boundary, as suggested by magnetic intensity data, the distribution of ultramafic igneous intrusions, and patterns of earthquake activity. The fault system was primarily active during the Alleghanian orogeny of Late Pennsylvanian and Early Permian time, when ultramatic igneous magma intruded along en echelon tensional fractures. ?? 2004 Geological Society of America.

  9. A re-assessment of the faulting in the 1967 Mogod earthquakes in Mongolia

    NASA Astrophysics Data System (ADS)

    Bayasgalan, A.; Jackson, J. A.

    1999-09-01

    The 1967 January 5 Mogod earthquake (M_s 7.5, M_w 7.1) in Mongolia produced spectacular surface faulting and has been the subject of several previous seismological and field reports. However, early field accounts were sketchy, and existing seismological analyses preceded the detailed field descriptions that are now available. In this paper we synthesize information on surface ruptures (both published and supplemented by our own observations), geomorphology and satellite imagery with a new seismological analysis of long-period P and SH waveforms and aftershock relocations to produce a description of the faulting in the Mogod earthquake sequence that is self-consistent and compatible with all this information. The main shock ruptured in three subevents occurring sequentially from north to south, all of them associated with segments of coseismic surface faulting. The first and second subevents involved predominantly N-S right-lateral strike slip, with the second, larger one occurring on a fault dipping steeply east with a significant reverse component of slip. The third subevent involved thrust faulting with a NW-SE strike at the southern end of the strike-slip faulting. A large (M_w 6.4) aftershock on January 20 was associated with a different thrust fault segment, which terminates the southern end of the strike-slip rupture in the first subevent. The association of the surface faulting and seismology with the geomorphology gives some insight into how the faulting in this region evolves with time.

  10. Damage to the shallow Landers fault from the nearby Hector Mine earthquake.

    PubMed

    Vidale, John E; Li, Yong-Gang

    2003-01-30

    Crustal faults have long been identified as sites where localized sliding motion occurs during earthquakes, which allows for the relative motion between adjacent crustal blocks. Although there is a growing awareness that we must understand the evolution of fault systems on many timescales to relate present-day crustal stresses and fault motions to geological structures formed in the past, fault-zone damage and healing have been documented quantitatively in only a few cases. We have been monitoring the healing of damage on the shallow Johnson Valley fault after its rupture in the 1992 magnitude-7.3 Landers earthquake, and here we report that this healing was interrupted in 1999 by the magnitude-7.1 Hector Mine earthquake rupture, which occurred 20-30 km away. The Hector Mine earthquake both strongly shook and permanently strained the Johnson Valley fault, adding damage discernible as a temporary reversal of the healing process. The fault has since resumed the trend of strength recovery that it showed after the Landers earthquake. These observations lead us to speculate that fault damage caused by strong seismic waves may help to explain earthquake clustering and seismicity triggering by shaking, and may be involved in friction reduction during faulting. PMID:12556890

  11. Estimation of upper limit of pore pressure by fault stability analysis

    NASA Astrophysics Data System (ADS)

    Chen, Zijian; Deng, Jingen; Yu, Baohua; Zhang, Yanan; Chen, Zhuo

    2016-06-01

    Generally, the pore pressure for a pre-drill well is predicted using empirical parameters, which are regressed from the drilled well's data. However, for areas with large geological differences, empirical parameters which are obtained using traditional methods may fail because intense tectonic movement would result in huge differences between the pre-drill well and drilled well. Firstly, in order to overcome this problem, the method of fault stability analysis is introduced. Analysis indicates that when abnormal overpressure exceeds a certain value, the fault ruptures and the overpressured fluid escapes, so that there is an upper limit of pore pressure (ULPP) for the stable fault. Secondly, the influences of fault angle, formation Poisson ratio and modulus of elasticity on the ULPP are discussed further. The results show that the ULPP of a fault with angle of 65.2° is the minimum, and the critical angle increases with the increase of internal friction coefficient. For reverse faults and strike faults, the influences of Poisson ratio and modulus of elasticity are small, but for normal faults these are significant. Finally, three kinds of ULPP for these different faults are proposed, respectively. The application of this method in the Xihu Sag in the East China Sea has proved that reference to ULPP can verify and correct regressed empirical parameters, so as to improve pore pressure prediction accuracy.

  12. Regional significance of recurrent faulting and intracanyon volcanism at Oak Creek Canyon, southern Colorado Palteau, Arizona

    SciTech Connect

    Holm, R.F. ); Cloud, R.A. )

    1990-10-01

    Measured sections of late Miocene basalt lava flows, Tertiary gravel, and Paleozoic strata are the basis for stratigraphic reconstructions that provide evidence for pre- and post-volcanic movements on the Oak Creek fault, and for the existence of a prevolcanic ancestral Oak Creek Canyon, Arizona. Recurrent faulting, recording Laramide compression and Basin and Range extension, suggests probable control by an ancestral Oak Creek fault that would belong to a regional system of basement faults hat have controlled Colorado Plateau structures in Phanerozoic rocks. Locally derived Tertiary gravel and overlying lavas filled a canyon eroded in Paleozoic strata along the Oak Creek fault. Southward flow of ancestral Oak Creek, indicated y the lithology and geomorphic position of the gravel, valley reconstruction, and lava vents to the north, northeast, or east, requires that the regional drainage reversal on the southern Colorado Plateau occurred before late Miocene time in the Oak Creek area.

  13. 5.9 Mw, 18th June 2010 earthquake and fault segment linkage at Andaman - A study based on macroseismic survey, GPS geodesy and Coulomb stress changes

    NASA Astrophysics Data System (ADS)

    Som, S. K.; Jana, Prasun; Mohapatra, S. R.; Nayak, S. K.; Saha, Ashim Kumar

    2013-05-01

    18th June, 2010 5.9 Mw earthquake at North Andaman triggered along NW-SE pre-existing fault with reverse fault mechanism. Macroseismic survey and GPS geodesy reveal maximum damages following NE-SW trend due to normal fault mechanism. Coulomb stress modeling for post- and inter-seismic earthquakes after the 2004 mega-earthquake show different stages of fault segment linkage at North Andaman. The present earthquake has been explained as co-shock due to asiesmic soft linkage of fault propagation.

  14. 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

  15. Finding concealed active faults: Extending the southern Whidbey Island fault across the Puget Lowland, Washington

    NASA Astrophysics Data System (ADS)

    Sherrod, Brian L.; Blakely, Richard J.; Weaver, Craig S.; Kelsey, Harvey M.; Barnett, Elizabeth; Liberty, Lee; Meagher, Karen L.; Pape, Kristin

    2008-05-01

    The southern Whidbey Island fault zone (SWIF), as previously mapped using borehole data, potential field anomalies, and marine seismic reflection surveys, consists of three subparallel, northwest trending strands extending ˜100 km from near Vancouver Island to the northern Puget Lowland. East of Puget Sound, the SWIF makes landfall between the cities of Seattle and Everett but is concealed beneath a thick mantle of young glacial deposits and vegetation. A ˜20-km-wide, northwest trending swath of subparallel, low-amplitude aeromagnetic anomalies crosses this region of the Puget Lowland and is on strike with the SWIF. The most prominent aeromagnetic anomaly, the Cottage Lake lineament, extends at least 18 km and lies approximately on strike with the SWIF on Whidbey Island. Subtle scarps and topographic lineaments on Pleistocene surfaces, visible on high-resolution lidar topography at a number of locations along the SWIF, lie on or near these magnetic anomalies. In the field, scarps exhibit northeast-side-up and vertical relief of 1 to 5 m. Excavations across several lidar scarps lying on or near magnetic anomalies show evidence for multiple folding and faulting events since deglaciation, most likely above buried reverse/oblique faults. Excavations in areas away from magnetic anomalies do not show evidence of tectonic deformation. In total, paleoseismological evidence suggests that the SWIF produced at least four earthquakes since deglaciation about 16,400 years ago, the most recent less than 2700 years ago.

  16. Fault Management Design Strategies

    NASA Technical Reports Server (NTRS)

    Day, John C.; Johnson, Stephen B.

    2014-01-01

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

  17. 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.

  18. Colorado Regional Faults

    DOE Data Explorer

    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

  19. Dynamics of fault interaction - Parallel strike-slip faults

    NASA Astrophysics Data System (ADS)

    Harris, Ruth A.; Day, Steven M.

    1993-03-01

    We use a 2D finite difference computer program to study the effect of fault steps on dynamic ruptures. Our results indicate that a strike-slip earthquake is unlikely to jump a fault step wider than 5 km, in correlation with field observations of moderate to great-sized earthquakes. We also find that dynamically propagating ruptures can jump both compressional and dilational fault steps, although wider dilational fault steps can be jumped. Dilational steps tend to delay the rupture for a longer time than compressional steps do. This delay leads to a slower apparent rupture velocity in the vicinity of dilational steps. These 'dry' cases assumed hydrostatic or greater pore-pressures but did not include the effects of changing pore pressures. In an additional study, we simulated the dynamic effects of a fault rupture on 'undrained' pore fluids to test Sibson's (1985, 1986) suggestion that 'wet' dilational steps are a barrier to rupture propagation. Our numerical results validate Sibson's hypothesis.

  20. 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.

  1. Towards reversible basic linear algebra subprograms: A performance study

    SciTech Connect

    Perumalla, Kalyan S.; Yoginath, Srikanth B.

    2014-12-06

    Problems such as fault tolerance and scalable synchronization can be efficiently solved using reversibility of applications. Making applications reversible by relying on computation rather than on memory is ideal for large scale parallel computing, especially for the next generation of supercomputers in which memory is expensive in terms of latency, energy, and price. In this direction, a case study is presented here in reversing a computational core, namely, Basic Linear Algebra Subprograms, which is widely used in scientific applications. A new Reversible BLAS (RBLAS) library interface has been designed, and a prototype has been implemented with two modes: (1) a memory-mode in which reversibility is obtained by checkpointing to memory in forward and restoring from memory in reverse, and (2) a computational-mode in which nothing is saved in the forward, but restoration is done entirely via inverse computation in reverse. The article is focused on detailed performance benchmarking to evaluate the runtime dynamics and performance effects, comparing reversible computation with checkpointing on both traditional CPU platforms and recent GPU accelerator platforms. For BLAS Level-1 subprograms, data indicates over an order of magnitude better speed of reversible computation compared to checkpointing. For BLAS Level-2 and Level-3, a more complex tradeoff is observed between reversible computation and checkpointing, depending on computational and memory complexities of the subprograms.

  2. Towards reversible basic linear algebra subprograms: A performance study

    DOE PAGESBeta

    Perumalla, Kalyan S.; Yoginath, Srikanth B.

    2014-12-06

    Problems such as fault tolerance and scalable synchronization can be efficiently solved using reversibility of applications. Making applications reversible by relying on computation rather than on memory is ideal for large scale parallel computing, especially for the next generation of supercomputers in which memory is expensive in terms of latency, energy, and price. In this direction, a case study is presented here in reversing a computational core, namely, Basic Linear Algebra Subprograms, which is widely used in scientific applications. A new Reversible BLAS (RBLAS) library interface has been designed, and a prototype has been implemented with two modes: (1) amore » memory-mode in which reversibility is obtained by checkpointing to memory in forward and restoring from memory in reverse, and (2) a computational-mode in which nothing is saved in the forward, but restoration is done entirely via inverse computation in reverse. The article is focused on detailed performance benchmarking to evaluate the runtime dynamics and performance effects, comparing reversible computation with checkpointing on both traditional CPU platforms and recent GPU accelerator platforms. For BLAS Level-1 subprograms, data indicates over an order of magnitude better speed of reversible computation compared to checkpointing. For BLAS Level-2 and Level-3, a more complex tradeoff is observed between reversible computation and checkpointing, depending on computational and memory complexities of the subprograms.« less

  3. Dynamic rupture modeling of the transition from thrust to strike-slip motion in the 2002 Denali fault earthquake, Alaska

    USGS Publications Warehouse

    Aagaard, B.T.; Anderson, G.; Hudnut, K.W.

    2004-01-01

    We use three-dimensional dynamic (spontaneous) rupture models to investigate the nearly simultaneous ruptures of the Susitna Glacier thrust fault and the Denali strike-slip fault. With the 1957 Mw 8.3 Gobi-Altay, Mongolia, earthquake as the only other well-documented case of significant, nearly simultaneous rupture of both thrust and strike-slip faults, this feature of the 2002 Denali fault earthquake provides a unique opportunity to investigate the mechanisms responsible for development of these large, complex events. We find that the geometry of the faults and the orientation of the regional stress field caused slip on the Susitna Glacier fault to load the Denali fault. Several different stress orientations with oblique right-lateral motion on the Susitna Glacier fault replicate the triggering of rupture on the Denali fault about 10 sec after the rupture nucleates on the Susitna Glacier fault. However, generating slip directions compatible with measured surface offsets and kinematic source inversions requires perturbing the stress orientation from that determined with focal mechanisms of regional events. Adjusting the vertical component of the principal stress tensor for the regional stress field so that it is more consistent with a mixture of strike-slip and reverse faulting significantly improves the fit of the slip-rake angles to the data. Rotating the maximum horizontal compressive stress direction westward appears to improve the fit even further.

  4. Reverse Correlation in Neurophysiology

    ERIC Educational Resources Information Center

    Ringach, Dario; Shapley, Robert

    2004-01-01

    This article presents a review of reverse correlation in neurophysiology. We discuss the basis of reverse correlation in linear transducers and in spiking neurons. The application of reverse correlation to measure the receptive fields of visual neurons using white noise and m-sequences, and classical findings about spatial and color processing in…

  5. Eastern termination of the Altyn Tagh Fault, western China: Constraints from a magnetotelluric survey

    NASA Astrophysics Data System (ADS)

    Xiao, Qibin; Shao, Guihang; Liu-Zeng, Jing; Oskin, Michael E.; Zhang, Jin; Zhao, Guoze; Wang, Jijun

    2015-05-01

    The left-lateral Altyn Tagh Fault forms the northern boundary of the Tibetan Plateau. The strike-slip rate of the active Altyn Tagh Fault decreases northeastward and reduces close to zero as it passes north of the Qilian Shan. This geometry raises controversies on whether and how the fault terminates or extends further east. To address these controversies, wide-band magnetotelluric data were collected along four profiles across the Altyn Tagh Fault ranging from 135 to 261 km in length. All four profiles are located in the foreland of the Qilian Shan Ranges and are oriented perpendicular to the inferred fault zone that could be the continuation of Altyn Tagh Fault. Both the two-dimensional and three-dimensional electrical resistivity models derived from our magnetotelluric data show that the Hexi Corridor crust is generally of low resistivity, whereas the crust of the Huahai-Jinta basin is, in general, of high resistivity with a local and isolated low-resistivity anomaly within the mid-lower crust. The generally high-resistivity crust of the Huahai-Jinta basin may be rheologically unfavorable for the Altyn Tagh Fault passing through the basin toward the northeast. The entirely different electrical structure between the Hexi Corridor and its northern neighbors indicates the existence of a tectonic boundary that coincides with the Altyn Tagh Fault in the west and reverse faults in the east. The two-dimensional electrical conductivity models suggest that the Altyn Tagh Fault transfers from a single fault in the west to a branching set of mainly dip-slip faults in the east.

  6. The southern Whidbey Island fault: An active structure in the Puget Lowland, Washington

    USGS Publications Warehouse

    Johnson, S.Y.; Potter, C.J.; Armentrout, J.M.; Miller, J.J.; Finn, C.; Weaver, C.S.

    1996-01-01

    Information from seismic-reflection profiles, outcrops, boreholes, and potential field surveys is used to interpret the structure and history of the southern Whidbey Island fault in the Puget Lowland of western Washington. This northwest-trending fault comprises a broad (as wide as 6-11 km), steep, northeast-dipping zone that includes several splays with inferred strike-slip, reverse, and thrust displacement. Transpressional deformation along the southern Whidbey Island fault is indicated by alongstrike variations in structural style and geometry, positive flower structure, local unconformities, out-of-plane displacements, and juxtaposition of correlative sedimentary units with different histories. The southern Whidbey Island fault represents a segment of a boundary between two major crustal blocks. The Cascade block to the northeast is floored by diverse assemblages of pre-Tertiary rocks; the Coast Range block to the southwest is floored by lower Eocene marine basaltic rocks of the Crescent Formation. The fault probably originated during the early Eocene as a dextral strike-slip fault along the eastern side of a continental-margin rift. Bending of the fault and transpressional deformation began during the late middle Eocene and continues to the present. Oblique convergence and clockwise rotation along the continental margin are the inferred driving forces for ongoing deformation. Evidence for Quaternary movement on the southern Whidbey Island fault includes (1) offset and disrupted upper Quaternary strata imaged on seismic-reflection profiles; (2) borehole data that suggests as much as 420 m of structural relief on the Tertiary-Quaternary boundary in the fault zone; (3) several meters of displacement along exposed faults in upper Quaternary sediments; (4) late Quaternary folds with limb dips of as much as ???9??; (5) large-scale liquefaction features in upper Quaternary sediments within the fault zone; and (6) minor historical seismicity. The southern Whidbey

  7. 20 CFR 404.507 - Fault.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

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

  8. 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.

  9. Novel Parity-Preserving Designs of Reversible 4-Bit Comparator

    NASA Astrophysics Data System (ADS)

    Qi, Xue-mei; Chen, Fu-long; Wang, Hong-tao; Sun, Yun-xiang; Guo, Liang-min

    2014-04-01

    Reversible logic has attracted much attention in recent years especially when the calculation with minimum energy consumption is considered. This paper presents two novel approaches for designing reversible 4-bit comparator based on parity-preserving gates, which can detect any fault that affects no more than a single logic signal. In order to construct the comparator, three variable EX-OR gate (TVG), comparator gate (CPG), four variable EX-OR gate block (FVGB) and comparator gate block (CPGB) are designed, and they are parity-preserving and reversible. Their quantum equivalent implementations are also proposed. The design of two comparator circuits is completed by using existing reversible gates and the above new reversible circuits. All these comparators have been modeled and verified in Verilog hardware description language (Verilog HDL). The Quartus II simulation results indicate that their circuits' logic structures are correct. The comparative results are presented in terms of quantum cost, delay and garbage outputs.

  10. Superposed local and regional paleostresses: Fault-slip analysis of Neogene extensional faulting near coeval caldera complexes, Yucca Flat, Nevada

    SciTech Connect

    Minor, S.A.

    1995-06-10

    Numerous reduced stress tensors are computed by multiple inversions of 906 temporally and spatially partitioned fault-slip data from the Yucca Flat region in the southwest Nevada volcanic field to constrain the Neogene paleostress and faulting history and to investigate how the regional tectonic stress field was affected by local caldera magmatism. Perturbed, shallow (<400 m), pre-11 Ma paleostress configurations, determined west and northwest of present (post-11 Ma) Yucca Flat basin, existed during mild extensional faulting and are attributed to superposition of transient caldera-magmatic stresses on the regional stress field. A brief ({approximately} 0.5 m.y.) change to a strike-slip stress state occurred at about 13 Ma and was accompanied by small-offset, quasi-conjugate strike-slip faulting. This stress state was most distinct, relative to a normalslip state, near calderas where stress solutions and fault relations indicate closer affinities to a reverse-slip state. Inferred 11.6-11.45 Ma paleostress tensors indicate radial tension associated with either initial caldera collapse or local post-collapse topographic modification of the stress field. Post-11 Ma normal-slip stress tensors are associated with normal- and oblique-slip faults that accommodated subsidence and eastward extension of Yucca Flat basin away from the caldera complexes. These tensors do not indicate stress modifications due to residual caldera-related effects and thus were used to infer post-11 Ma regional stress changes. The stress field has rotated as much as 65{degrees} clockwise since 11 Ma during extensional development of Yucca Flat basin, with most of the rotation and extension occurring before about 8.5 Ma. Results suggest that shallow magmatism and caldera development can strongly alter extensional tectonic stress fields, fault patterns, and slip directions in the uppermost crust out to distances of roughly two magma chamber radii away from a magma body. 59 refs., 11 figs., 2 tabs.

  11. Geophysical Anomalies and Seismicity Suggest a Connection Between the Hayward and Calaveras Faults, Eastern San Francisco Bay Area, Northern California

    NASA Astrophysics Data System (ADS)

    Ponce, D. A.; Phelps, G. A.; Graymer, R. W.; Jachens, R. C.; Simpson, R. W.; Wentworth, C. M.

    2003-12-01

    Gravity, magnetic, and seismicity data of the eastern San Francisco Bay Area are used to reveal the three-dimensional subsurface geologic structure of the eastern San Francisco Bay Area and its relationship to ongoing seismicity. Combined, these data suggest a connection between the Hayward and Calaveras Faults. Gravity and magnetic modeling of a tabular gabbro body near San Leandro and relocated, double-difference seismicity data along the Hayward Fault (Ellsworth et al., 2000) suggest that the Hayward Fault dips to the northeast. Further southeast, double-difference seismicity data indicate that the fault dip becomes shallower, possibly connecting the creeping surface trace of the Hayward Fault with the diverging Mission seismicity trend at depth as suggested by Manaker and Michael (2003). In the stepover region, the southern extension of the Hayward Fault is parallel to the active central Calaveras Fault for about 25 km and the 4-km wide area in between is characterized by en echelon reverse (oblique?) faults. At depths below about 5 km, seismicity appears to be continuous, connecting the Hayward fault to the left-stepping central Calaveras Fault along the Mission seismicity trend. Geophysical interpretation of offset magnetic rock units also suggests that the northern Calaveras Fault has at most a few tens of kilometers of total offset and that most slip may be transferred from the southern Calaveras Fault, with a total offset of about 175 km, along the central Calaveras, Silver Creek, Hayward, and other faults west of the northern Calaveras Fault, consistent with present seismicity. Cross-sectional and 3D visualizations of these data are used to illustrate the proposed geometry of the connection between the Hayward and Calaveras Faults.

  12. Three-dimensional dynamic rupture simulations across interacting faults: The Mw7.0, 2010, Haiti earthquake

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    The mechanisms controlling rupture propagation between fault segments during a large earthquake are key to the hazard posed by fault systems. Rupture initiation on a smaller fault sometimes transfers to a larger fault, resulting in a significant event (e.g., 2002 M7.9 Denali USA and 2010 M7.1 Darfield New Zealand earthquakes). In other cases rupture is constrained to the initial fault and does not transfer to nearby faults, resulting in events of more moderate magnitude. This was the case of the 1989 M6.9 Loma Prieta and 2010 M7.0 Haiti earthquakes which initiated on reverse faults abutting against a major strike-slip plate boundary fault but did not propagate onto it. Here we investigate the rupture dynamics of the Haiti earthquake, seeking to understand why rupture propagated across two segments of the Léogâne fault but did not propagate to the adjacent Enriquillo Plantain Garden Fault, the major 200 km long plate boundary fault cutting through southern Haiti. We use a finite element model to simulate propagation of rupture on the Léogâne fault, varying friction and background stress to determine the parameter set that best explains the observed earthquake sequence, in particular, the ground displacement. The two slip patches inferred from finite fault inversions are explained by the successive rupture of two fault segments oriented favorably with respect to the rupture propagation, while the geometry of the Enriquillo fault did not allow shear stress to reach failure.

  13. Accelerometer having integral fault null

    NASA Technical Reports Server (NTRS)

    Bozeman, Richard J., Jr. (Inventor)

    1995-01-01

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

  14. Experimental Fault Reactivation on Favourably and Unfavourably Oriented Faults

    NASA Astrophysics Data System (ADS)

    Mitchell, T. M.; Renner, J.; Sibson, R. H.

    2011-12-01

    In this study, we assess the loading of faults to failure under different stress regimes in a triaxial deformation apparatus, both in dry and saturated conditions. We explore experimentally the reshear of an existing fault in various orientations for particular values of (σ_1 - σ_3) and σ_3' for contrasting loading systems - load-strengthening (equivalent to a thrust fault) with σ1' increasing at constant σ_3', versus load-weakening (equivalent to a normal fault) with reducing σ_3' under constant σ_1'. Experiments are conducted on sawcut granite samples with fault angles at a variety of orientations relative to σ_1, ranging from an optimal orientation for reactivation to lockup angles where new faults are formed in preference to reactivating the existing sawcut orientation. Prefailure and postfailure behaviour is compared in terms of damage zone development via monitoring variations in ultrasonic velocity and acoustic emission behaviour. For example, damage surrounding unfavourably oriented faults is significantly higher than that seen around favourably orientated faults due to greater maximum stresses attained prior to unstable slip, which is reflected by the increased acoustic emission activity leading up to failure. In addition, we explore reshear conditions under an initial condition of (σ_1' = σ_3'), then inducing reshear on the existing fault first by increasing σ_1'(load-strengthening), then by decreasing σ_3' (load-weakening), again comparing relative damage zone development and acoustic emission levels. In saturated experiments, we explore the values of pore fluid pressure (P_f) needed for re-shear to occur in preference to the formation of a new fault. Typically a limiting factor in conventional triaxial experiments performed in compression is that P_f cannot exceed the confining pressure (σ_2 and σ_3). By employing a sample assembly that allows deformation while the loading piston is in extension, it enables us to achieve pore pressures in

  15. How do normal faults grow?

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  16. Tectonic Geomorphology of the Hanging Wall Blocks of the Cimandiri Fault Zone, West Java, Indonesia

    NASA Astrophysics Data System (ADS)

    Marliyani, G. I.; Arrowsmith, R.

    2014-12-01

    In areas where regional strain is accommodated by broad zones of short and low slip-rate faults, geomorphic and paleoseismic characterization of faults is difficult because of poor surface expression and long earthquake recurrence intervals. In humid areas, faults can be buried by thick sediments and undetectable until the next earthquake. In Java, despite the frequency of damaging shallow earthquakes, active faults are diffuse and their characterization is challenging. Among them is the ENE-trending Cimandiri fault. Cumulative displacement along the fault produces prominent ENE-oriented ranges with the east side moving relatively upward and to the north. Along its length, the few hundred meter wide fault zone is expressed in the bedrock by numerous NE, E and NW-trending thrust- and strike slip faults and folds. However, it is unclear which of these structures are active, as the diffuse nature of the fault zone has so far stymied conventional paleoseismic study. To address this, we performed a tectonic geomorphology analysis of the fault zone. We used the 30-m resolution SRTM-DEM to construct longitudinal profiles of 601 bedrock rivers along the ranges and calculated the normalized channel steepness index (ksn). Our preliminary results rely on the assumption that ksn is a reasonable proxy for relative rock uplift rate in a region, assuming variations in rock type and climate are insignificant. While the active traces of the Cimandiri fault are obscured, the spatial variation in ksn allows us to delineate 4 discontinuous hanging wall blocks that vary between E and NE striking along the zone. The largest ksn values are along the central-western block (Cibeber area). The longest block is in the central eastern portion of the fault zone and comprises 45 km of the 100 km long fault zone. The fault bifurcates at its eastern termination and steps into the Lembang fault. The distribution of ksn suggests that reverse motion is more dominant than lateral because of a lack of

  17. Differential Fault Analysis of Rabbit

    NASA Astrophysics Data System (ADS)

    Kircanski, Aleksandar; Youssef, Amr M.

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

  18. Quantum Operation Time Reversal

    SciTech Connect

    Crooks, Gavin E.

    2008-03-25

    The dynamics of an open quantum system can be described by a quantum operation: A linear, complete positive map of operators. Here, I exhibit a compact expression for the time reversal of a quantum operation, which is closely analogous to the time reversal of a classical Markov transition matrix. Since open quantum dynamics are stochastic, and not, in general, deterministic, the time reversal is not, in general, an inversion of the dynamics. Rather, the system relaxes toward equilibrium in both the forward and reverse time directions. The probability of a quantum trajectory and the conjugate, time reversed trajectory are related by the heat exchanged with the environment.

  19. 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

  20. Paleoseismology of the Denali fault at the Nenana River

    NASA Astrophysics Data System (ADS)

    Taylor, T. P.; Bemis, S. P.

    2012-12-01

    additional fine grained sediment below our exposed stratigraphy. DM2 exposed a series of north-dipping reverse faults and south-dipping normal faults suggesting multiple deformational events. Fault displacements in both DM1 and DM2 trenches are well-constrained by organic-bearing horizons and dating of radiocarbon samples from these horizons are in progress. The thickness of fine-grained sediment and abundant dateable material illustrate the significant potential for this site to expand the paleoseismic record of the Denali fault. Furthermore, our interpretation of the emplacement of these fine-grained sediments suggests significant flood events during the recent history of the Nenana River.

  1. 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.

  2. Tectonic dynamics and correlation of major earthquake sequences of the Xiaojiang and Qujiang-Shiping fault systems, Yunnan, China

    NASA Astrophysics Data System (ADS)

    Xue-Ze, Wen; Fang, Du; Feng, Long; Jun, Fan; Hang, Zhu

    2013-04-01

    The N-S trending Xiaojiang fault zone and the NW-SE trending Qujiang-Shiping fault zone are adjacent active fault systems and seismogenic zones associated with strong and major earthquakes in Yunnan, China. To understand the interaction of the two fault systems, and its probable influence on earthquake occurrences, we conduct a synthetic study based on data of active tectonics, historical earthquakes, relocated small earthquakes, GPS station velocities and focal mechanism resolutions. Our study makes several conclusions. (1) The active southward motion of the western side of the Xiaojiang fault zone (i.e. the side of the Sichuan-Yunnan block) has a persistent and intensive effect on the Qujiang-Shiping fault zone. The later fault zone has absorbed and transformed the southward motion of the western side of the former fault zone through dextral strike-slip/shearing as well as transverse shortening/thrusting. (2) Along the Xiaojiang fault zone, the present sinistral strike-slip/shearing rate decreases from 10 and 8 mm/a on the northern, central and central-southern segments to 4 mm/a on the southern segment. The decreased rate has been adjusted in the area along and surrounding the Qujiang-Shiping fault zone through reverse-dextral faulting and distributed shearing and shortening. (3) The tectonic-dynamic relation between the Xiaojiang fault zone and the Qujiang-Shiping fault zone is also manifested by a close correlation of earthquake occurrences on the two fault zones. From 1500 to 1850 a sequence of strong and major earthquakes occurred along the Xiaojiang fault zone and its northern neighbor, the Zemuhe fault zone, which was characterized by gradually accelerating strain release, gradually shortening intervals between M≥7 events, and major releases occurring in the mid to later stages of the sequence. As a response to this sequence, after an 88-year delay, another sequence of 383 years (from 1588 to 1970) of strong and major earthquakes occurred on the Qujiang

  3. Tectonics, magmatism and paleo-fluid distribution in a strike-slip setting: Insights from the northern termination of the Liquiñe-Ofqui fault System, Chile

    NASA Astrophysics Data System (ADS)

    Pérez-Flores, Pamela; Cembrano, José; Sánchez-Alfaro, Pablo; Veloso, Eugenio; Arancibia, Gloria; Roquer, Tomás

    2016-06-01

    This study addresses the interplay between strain/stress fields and paleo-fluid migration in the Southern Andean Volcanic Zone (SVZ). The SVZ coexists with the margin-parallel Liquiñe-Ofqui Fault System (LOFS) and with NW-striking Andean Transverse Faults (ATF). To tackle the role of different fault-fracture systems on deformation distribution and magma/fluid transport, we map the nature, geometry and kinematics of faults, veins and dikes at various scales. Fault-slip data analysis yields stress and strain fields from the full study area data base (regional scale) and fault zones representative of each fault system (local scale). Regional scale strain analysis shows kinematically heterogeneous faulting. Local strain analyses indicate homogeneous deformation with NE-trending shortening and NW-trending extension at NNE-striking Liquiñe-Ofqui master fault zones. Strain axes are clockwise rotated at second order fault zones, with ENE-trending shortening and NNW-trending stretching. The ATF record polyphasic deformation. Conversely, stress field analysis at regional scale indicates a strike-slip dominated transpressional regime with N64°E-trending σ1 and N30°W-trending σ3. Deformation is further partitioned within the arc through NNE-striking dextral-reverse faults, NE-striking dextral-normal faults and NW-striking sinistral-reverse faults with normal slip activation. The regional tectonic regime controls the geometry of NE-striking dikes and volcanic centers. NE-striking faults record local stress axes that are clockwise rotated with respect to the regional stress field. NNE- and NE-striking faults are favorably oriented for reactivation under the regional stress field and show poorly-developed damage zones. Conversely, NW-striking fault systems, misoriented under the regional stress field, show multiple fault cores, wider damage zones and dense vein networks. Deformation driven by oblique subduction is partially partitioned into strike-slip and shortening

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Subsurface structure along the eastern marginal fault zone of Yokote Basin by Seismic reflection profiling studies, Northeast Japan

    NASA Astrophysics Data System (ADS)

    Kagohara, K.; Imaizumi, T.; Echigo, T.; Miyauchi, T.; Sato, H.

    2005-12-01

    Typical reverse faults, which are known as Senya earthquake faults appeared along the western foot of the Mahiru Mountains, associated with The Rikuu Earthquake (Mj7.2) of 1896 in Northeast Japan. Eastern marginal fault zone of the Yokote Basin consist of four main surface ruptures, about 35 km long, Obonai fault, Shiraiwa fault, Ota fault and Senya fault, depending on their continuity and strike (Matsuda et al., 1980). We carried out the seismic reflection profiling across these faults (Kawaguchi03 Seismic line, Unjono04 Seismic line and Kotaki05 Seismic line) to clarify the subsurface structure of these reverse fault system based on the data of tectonic geomorphology and structural geology and furthermore, to discuss the timing of migration of the thrusting from the range front to the basin margin. The seismic source was mini-vibrator trucks, with 20seconds of 10-100Hz signals at 10m or 5m intervals. The sweep signals were recorded by a digital telemetry system (GDAPS-4a) with 10 Hz geophones. The obtained seismic reflection data were processed by conventional Common mid-point (CMP) methods, including post-stack migration and depth conversion. The resulting seismic reflection profile reveals a thrust structure beneath these areas. At the Center of Senya hills there are two thrusts and one high angle reverse fault (1997 Seismic Line). Senya fault is an active frontal emergent thrust with flat and ramp structure. Although, the high angle reverse fault, located along the foot of the range is a short-cut branching fault from the Senya fault in the central part of the Senya hill (Sato et al., 1998), in the Unjono04 seismic line, the depth of the flat and ramp structure gradually shallow in the north part of the Senya hill, where the flexure scarp accompanied with antithetic faults formed on the fluvial terraces. In the Kawaguchi03 seismic line, the concealed fault, 0.5km below the surface, branched from the master Ota fault, form a flexure scarplet on the alluvial fan

  9. Geophysical methods applied to fault characterization and earthquake potential assessment in the Lower Tagus Valley, Portugal

    NASA Astrophysics Data System (ADS)

    Carvalho, João; Cabral, João; Gonçalves, Rui; Torres, Luís; Mendes-Victor, Luís

    2006-06-01

    The study region is located in the Lower Tagus Valley, central Portugal, and includes a large portion of the densely populated area of Lisbon. It is characterized by a moderate seismicity with a diffuse pattern, with historical earthquakes causing many casualties, serious damage and economic losses. Occurrence of earthquakes in the area indicates the presence of seismogenic structures at depth that are deficiently known due to a thick Cenozoic sedimentary cover. The hidden character of many of the faults in the Lower Tagus Valley requires the use of indirect methodologies for their study. This paper focuses on the application of high-resolution seismic reflection method for the detection of near-surface faulting on two major tectonic structures that are hidden under the recent alluvial cover of the Tagus Valley, and that have been recognized on deep oil-industry seismic reflection profiles and/or inferred from the surface geology. These are a WNW-ESE-trending fault zone located within the Lower Tagus Cenozoic basin, across the Tagus River estuary (Porto Alto fault), and a NNE-SSW-trending reverse fault zone that borders the Cenozoic Basin at the W (Vila Franca de Xira-Lisbon fault). Vertical electrical soundings were also acquired over the seismic profiles and the refraction interpretation of the reflection data was carried out. According to the interpretation of the collected data, a complex fault pattern disrupts the near surface (first 400 m) at Porto Alto, affecting the Upper Neogene and (at least for one fault) the Quaternary, with a normal offset component. The consistency with the previous oil-industry profiles interpretation supports the location and geometry of this fault zone. Concerning the second structure, two major faults were detected north of Vila Franca de Xira, supporting the extension of the Vila Franca de Xira-Lisbon fault zone northwards. One of these faults presents a reverse geometry apparently displacing Holocene alluvium. Vertical offsets

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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?

  15. Neogene contraction between the San Andreas fault and the Santa Clara Valley, San Francisco Bay region, California

    USGS Publications Warehouse

    McLaughlin, R.J.; Langenheim, V.E.; Schmidt, K.M.; Jachens, R.C.; Stanley, R.G.; Jayko, A.S.; McDougall, K.A.; Tinsley, J.C.; Valin, Z.C.

    1999-01-01

    In the southern San Francisco Bay region of California, oblique dextral reverse faults that verge northeastward from the San Andreas fault experienced triggered slip during the 1989 M7.1 Loma Prieta earthquake. The role of these range-front thrusts in the evolution of the San Andreas fault system and the future seismic hazard that they may pose to the urban Santa Clara Valley are poorly understood. Based on recent geologic mapping and geophysical investigations, we propose that the range-front thrust system evolved in conjunction with development of the San Andreas fault system. In the early Miocene, the region was dominated by a system of northwestwardly propagating, basin-bounding, transtensional faults. Beginning as early as middle Miocene time, however, the transtensional faulting was superseded by transpressional NE-stepping thrust and reverse faults of the range-front thrust system. Age constraints on the thrust faults indicate that the locus of contraction has focused on the Monte Vista, Shannon, and Berrocal faults since about 4.8 Ma. Fault slip and fold reconstructions suggest that crustal shortening between the San Andreas fault and the Santa Clara Valley within this time frame is ~21%, amounting to as much as 3.2 km at a rate of 0.6 mm/yr. Rates probably have not remained constant; average rates appear to have been much lower in the past few 100 ka. The distribution of coseismic surface contraction during the Loma Prieta earthquake, active seismicity, late Pleistocene to Holocene fluvial terrace warping, and geodetic data further suggest that the active range-front thrust system includes blind thrusts. Critical unresolved issues include information on the near-surface locations of buried thrusts, the timing of recent thrust earthquake events, and their recurrence in relation to earthquakes on the San Andreas fault.

  16. Hosgri fault zone, offshore Santa Maria River to Point Arguello, California

    SciTech Connect

    Cummings, D.; Gaal, R.A.

    1987-05-01

    The Hosgri fault zone between the Santa Maria River and Point Arguello was studied using 1280 line km of digital CDP seismic reflection and analog seismic reflection data. The fault zone is interpreted as (1) being high angle within the upper 1.5 sec two-way traveltime (approximately 2500 m); (2) having apparent reverse displacement, east block relatively up; and (3) based on subbottom and 3.5-kHz data, not cutting apparent unconsolidated (assumed Quaternary) sediments. The fault zone is well defined at the north end of the survey area, 12 km offshore, where it consists of two subparallel faults. Although the apparent vertical offset in this area is reasonably distinct, the amount of strike-slip displacement could not be determined from the available data because of the absence of well-defined piercing points. These two faults curve eastward near 34/sup 0/40'N and latitude and horsetail, striking onshore between 34/sup 0/38'N and 34/sup 0/40'N latitude. These faults may be the offshore extensions of the Lompoc-Solvang fault on the south and one of the (buried) Santa Ynez River faults on the north.

  17. The unusual 3D interplay of basement fault reactivation and fault-propagation-fold development: A case study of the Laramide-age Stillwell anticline, west Texas (USA)

    NASA Astrophysics Data System (ADS)

    Surpless, Ben; Hill, Nicola; Beasley, Cara

    2015-10-01

    Subsurface fault geometries have a systematic influence on folds formed above those faults. We use the extraordinarily well-exposed fold geometries of the Laramide-age Stillwell anticline in west Texas (USA) to develop a strain-predictive model of fault-propagation fold formation. The anticline is a 10-km long, NW-trending, NE-vergent, asymmetric fold system with an axis that displays a map-view left-stepping, en echelon pattern. We integrated field observations, geologic and structural data, cross-sections, and 2D kinematic modeling to establish an unusual 3D two-stage model of contractional fold formation, including: 1) reverse reactivation of a pre-existing, NW-striking, SW-dipping, left-stepping, en echelon normal fault system in Paleozoic basement rocks to generate monoclinal flexures in overlying layered Cretaceous carbonate rocks; and 2) the formation of a subsequent flat-ramp fault system that propagated horizontally along a mechanically-weak, clay-rich Cretaceous unit before ramping up at the hinge of the pre-existing monocline system. Strain is focused within the forelimb of the system, in front of the propagating fault tip, and is accommodated by a combination of interlayer slip, flat-ramp faulting, and fracturing proximal to planes of slip. This strain predictive model can be applied to similar, less-well-exposed contractional systems worldwide and provides a new, unusual example of Laramide-age contractional deformation.

  18. Characterising Active Fault Earthquake Sources Beneath the Coastal Environments of Christchurch and Wellington Cities, New Zealand, Using Seismic Reflection Profiles and Fault Displacement Analysis Techniques

    NASA Astrophysics Data System (ADS)

    Barnes, P.; Nodder, S.; Gorman, A. R.; Woelz, S.; Orpin, A. R.

    2014-12-01

    The coastal cities of Christchurch and Wellington, New Zealand, lie in different tectonic settings within the obliquely convergent Pacific-Australian plate boundary zone. Both cities have experienced damaging earthquakes in the last three years, which highlight the importance of locating and characterising hidden active faults close to urban areas. The devastating and geologically complex Canterbury earthquake sequence of 2010-2012 developed on the periphery of the plate boundary, and reactivated several previously unidentified strike-slip and reverse faults. Major aftershocks initially beneath land, generally migrated eastward over time, and finally advanced offshore into Pegasus Bay. A study of active submarine faulting beneath the bay highlights the role of inherited crustal structure and inversion tectonics. Marine seismic reflection data reveals that faults have very low slip rate and negligible post-glacial (<15 ka) deformation, which is consistent with inferred long recurrence intervals between large magnitude (Mw>6) earthquakes. Wellington City is surrounded by numerous high-slip rate strike-slip faults overlying the Hikurangi subduction zone. A dense network of secondary basement structures previously recognised throughout the region, mainly from tectonic geomorphology, have, until recently, been considered mostly inactive and excluded from seismic hazard models. We used high-resolution geophysical, bathymetric and sediment-core data to determine the structure, earthquake history and earthquake potential of a newly discovered active reverse fault beneath the inner reaches of Wellington Harbour. The fault has a slip rate of ~0.6 ± 0.3 mm/y, and a vertical displacement history indicating at least two large magnitude (Mw 6.3-7.1), surface-rupturing earthquakes in the last 10 ka. We infer that the fault extends southwards onshore beneath the city and potentially into Cook Strait, and represents a significant previously unrecognised seismic hazard.

  19. 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.

  20. An active footwall shortcut thrust revealed by seismic reflection profiling: a case study of the Futaba fault, northern Honshu, Japan

    NASA Astrophysics Data System (ADS)

    Sato, Hiroshi; Ishiyama, Tatsuya; Kato, Naoko; Higashinaka, Motonori; Kurashimo, Eiji; Iwasaki, Takaya; Abe, Susumu

    2013-04-01

    The Futaba fault is located along the Pacific cast of southern part of Northern Honshu and continues at least 100 km. Based on tectonic morphological research, its central part show the active tectonic features. Due to the effect of M9 Tohoku Oki earthquake 2011, the evaluation of Coulomb stress changes on the fault surface is concerned for the assess of seismic hazards. To investigate the deep geometry of seismogenic source fault and basic crustal structure, we performed deep seismic reflection profiling along the 58-km-long seismic line across the Futaba fault. The seismic data were obtained using four vibroseis trucks and 1164 channel recorders. The seismic section portrays the half graben filled by 1000-m-thick lower Miocene fluvial sediments, suggesting that the Futaba fault reactivated as a west dipping normal fault during the early Miocene associated with opening of the Sea of Japan. On the hanging wall of the Miocene normal fault, Mesozoic metamorphic rocks are cropping out forming a narrow range parallel to the fault. On the footwall of this range, footwall shortcut thrust is clearly identified by the deformation of Plio-Pleistocene sediments on the seismic section. The deeper extension of the Futaba fault can be traced down to 4.5 seconds (TWT) and sub-horizontal reflectors are developed around 6-7 seconds (TWT). The dip angle of the Futaba fault in the seismogenic zone is about 45 degrees. The footwall shortcut thrust was formed at the shallow high-angle part of the Futaba fault as a low-angle (30 degrees) reverse fault. The formation of half graben is limited along the northern part of this fault system. The footwall shortcut thrust was developed along a 40-km-long segment only accompanied with the Miocene half graben. The southern segment of the surface trace of the Futaba fault suggests a straight geometry may represent a change in dip angle.

  1. 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."

  2. Method of locating ground faults

    NASA Astrophysics Data System (ADS)

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

    1994-11-01

    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.

  3. 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.

  4. Granular packings and fault zones

    PubMed

    Astrom; Herrmann; Timonen

    2000-01-24

    The failure of a two-dimensional packing of elastic grains is analyzed using a numerical model. The packing fails through formation of shear bands or faults. During failure there is a separation of the system into two grain-packing states. In a shear band, local "rotating bearings" are spontaneously formed. The bearing state is favored in a shear band because it has a low stiffness against shearing. The "seismic activity" distribution in the packing has the same characteristics as that of the earthquake distribution in tectonic faults. The directions of the principal stresses in a bearing are reminiscent of those found at the San Andreas Fault. PMID:11017335

  5. Stress triggering in en echelon thrust ruptures and related tear faults: The 2003 M=6.9 Zemmouri, Algeria, earthquake and fault interactions

    NASA Astrophysics Data System (ADS)

    Lin, J.; Stein, R. S.; Meghraoui, M.; Toda, S.; Ayadi, A.; Dorbath, C.; Belabbes, S.

    2009-12-01

    The contractional tectonics of northern Algeria is characterized by a series of en echelon thrust faults of moderate lengths (Meghraoui et al., 2000). This tectonic deformation pattern is similar in geometry to other continental thrust fault systems, such as the Coalinga-Kettleman Hills faults in central California, but differs significantly from that of subduction zones, where thrust segments are often more geometrically continuous along the strike of subduction zones. In this study we first illustrate the essential features of stress interaction between earthquakes occurring on en echelon thrust faults and adjacent tear faults. Our model results reveal that earthquakes on en echelon thrust segments could significantly promote strike-slip motion on the intervening tear faults. Furthermore, if the source earthquake has mixed thrust and strike-slip components, the resultant stress increases on the tear faults are even greater. Thus, tear faults may play an important role in stress transfer between adjacent thrust segments. We next examine the stress transferred by the 2003 M=6.9 Zemmouri quake to nearby thrust and strike-slip faults in northern Algeria. Mahsas et al. (2008) illustrated that the observed afterslip in 2003-2005 appears to be concentrated at the upper parts of the 2003 Zemmouri rupture surface. Our calculations support the hypothesis that a significant portion (more than 75%) of the observed afterslip area might have experienced Coulomb stress increases during the Zemmouri main shock. Calculations further reveal that the majority (more than 90%) of the 30 best-relocated aftershocks as determined by Ayadi et al. (2008) also sustained Coulomb stress increases on at least one of their nodal planes. Finally, we calculated that the Zemmouri main shock brought the Coulomb stress 1 bar closer to failure on the adjacent Boumerdes reverse fault and 0.5 bars closer on the right-lateral Thenia faults that bound the Mitidja basin. Both of these faults experienced

  6. 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.

  7. Mechanical healing of simulated fault gouge

    NASA Astrophysics Data System (ADS)

    Messen, Y. H.; Corfdir, A.; Schmittbuhl, J.

    2013-04-01

    We investigate the origin of fast shear strength healing induced by mechanical perturbations during slide-release-slide (SRS) experiments using a ring shear apparatus (ACSA, Navier/CERMES, Ecole des Ponts ParisTech, France). A 100-mm-thick annular sample of siliceous sand (0.6 mm mean diameter) is submitted to shear by the mean of a rotating cylinder in a semi-Couette geometry. We explore the role of shear stress perturbations related to small reverse offsets of the loading interface. We show that controlled releases of the shear stress induce shear strength increases when resuming shear load (i.e. the Tightening-up effect of unloading or Tu-effect). However, a threshold of the shear stress perturbation amplitude to get a significant restrengthening is observed. The shear strength increase is shown to be logarithmically related to the amount of imposed reverse offset and linearly to the induced volumetric strain. These results suggest that small perturbations of the contact status (i.e. inelastic strain) in the granular assembly of the gouge interface, have a major influence on the fault restrengthening.

  8. Helena banks strike-slip(. ) fault and the relation to other Cenozoic faults along reactivated Triassic(. ) basin boundary fault zones in the Charleston, South Carolina, earthquake area - results from a marine high-resolution multichannel seismic-reflection survey

    SciTech Connect

    Behrendt, J.C.; Yuan, A.

    1985-01-01

    In 1981, the USGS conducted a high-resolution multichannel seismic (MCS) survey offshore of Charleston, South Carolina, to study the relation of Cenozoic faulting to future earthquake hazard. High-angle reverse displacement of Coastal Plain sedimentary rock indicating a linear increase with depth of 51 +/- 12 m/km is observed on the reflection profiles. This is similar to the Gants and Cooke faults in the meizoseismal area of the 1886 Charleston earthquake. The authors interpret these results to indicate that the stress field cannot have varied significantly in direction or in magnitude from Late Cretaceous time to Miocene or Pliocene time in the region. The HBF zone trends N 66/sup 0/ E; it comprises several 15- to 40-km-long segments that trend from N 68/sup 0/ E to N 77/sup 0/ E. The en-echelon pattern of the segments is compatible with left-lateral strike-slip and is thus consistent with the present northeast-trending maximum compressional stress field. The HBF zone appears to be an obliquely compressional reactivation of a tensional Triassic(.) fault zone bounding the Triassic(.) Kiawah Basin that has been identified on several MCS profiles. Similarly, the northeast-trending Gants reverse or strike-slip fault was probably reactivated from an old tensional fault bounding the Jedburg Triassic(.) basin in the 1886 meizoseismal area.

  9. Lidar reveals paleoseismic sites and recent strike-slip and thrust faulting along the central Alpine Fault, New Zealand

    NASA Astrophysics Data System (ADS)

    De Pascale, G. P.; Langridge, R. M.; Davies, T. R.

    2013-12-01

    In the South Island of New Zealand, the dextral-reverse Alpine fault forms the major plate boundary structure between the Pacific and Australian plates and is thought to fail in large to great earthquakes approximately every 100 to 400 years, with the most recent major surface rupture event occurring in 1717 AD. We used a recently collected lidar dataset to evaluate the central section of the fault to both measure recent slip along the fault, recent co-seismic uplift, and to find new paleoseismic sites. The new high-resolution topography in the dense temperate rainforest allowed insight into the fault that was previously unavailable. Lidar mapping, combined with field mapping facilitated the discovery of a multi-event thrust fault scarp of the Alpine Fault that was later trenched at Gaunt Creek. C-14 dating of units in the trench and mapping there, show that the last earthquake was probably the 1717 event. Along the length of the lidar survey, small (< 25 m) dextral offsets were also mapped along the fault, which were rated for quality, and then visited in the field. The lidar itself was a guide to locate these offsets, and the offset measurements in the field have lower uncertainties than the lidar resolution; dextral slip in the 1717 earthquake here was c. 7 m × 1 m. Additional sites with evidence for cumulative slip were also mapped in the field which showing repetitive slip of ~ 7 to 8 m per event for the past three surface ruptures on the fault. Sag ponds discovered during field mapping are important new targets for investigation and will likely yield slip-rate information here for the correlation of slip with events. Additional field mapping near the Whataroa River and Mint Creek demonstrates that between debris flow fans that cross the Alpine Fault at the rangefront of the Southern Alps, preservation of strike-slip scarps is rare due to post-earthquake deposition and erosion. However, one likely scarp was found in a post-earthquake aggradation surface

  10. Normal faults geometry and morphometry on Mars

    NASA Astrophysics Data System (ADS)

    Vaz, D. A.; Spagnuolo, M. G.; Silvestro, S.

    2014-04-01

    In this report, we show how normal faults scarps geometry and degradation history can be accessed using high resolution imagery and topography. We show how the initial geometry of the faults can be inferred from faulted craters and we demonstrate how a comparative morphometric analysis of faults scarps can be used to study erosion rates through time on Mars.

  11. 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 §...

  12. 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...

  13. 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...

  14. 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...

  15. 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...

  16. 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...

  17. 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 §...

  18. 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.

  19. 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.

  20. The fault-tree compiler

    NASA Technical Reports Server (NTRS)

    Martensen, Anna L.; Butler, Ricky W.

    1987-01-01

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

  1. Cell boundary fault detection system

    DOEpatents

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

    2009-05-05

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

  2. Weakening inside incipient thrust fault

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    In fold-and-thrust belts, shortening is mainly accommodated by thrust faults that nucleate along décollement levels. Geological and geophysical evidence suggests that these faults might be weak because of a combination of processes such as pressure-solution, phyllosilicates reorientation and delamination, and fluid pressurization. In this study we aim to decipher the processes and the kinetics responsible for weakening of tectonic décollements. We studied the Millaris thrust (Southern Pyrenees): a fault representative of a décollement in its incipient stage. This fault accommodated a total shortening of about 30 meters and is constituted by a 10m thick, intensively foliated phyllonite developed inside a homogeneous marly unit. Detailed chemical and mineralogical analyses have been carried out to characterize the mineralogical change, the chemical transfers and volume change in the fault zone compared to non-deformed parent sediments. We also carried out microstructural analysis on natural and experimentally deformed rocks. Illite and chlorite are the main hydrous minerals. Inside fault zone, illite minerals are oriented along the schistosity whereas chlorite coats the shear surfaces. Mass balance calculations demonstrated a volume loss of up to 50% for calcite inside fault zone (and therefore a relative increase of phyllosilicates contents) because of calcite pressure solution mechanisms. We performed friction experiments in a biaxial deformation apparatus using intact rocks sheared in the in-situ geometry from the Millaris fault and its host sediments. We imposed a range of normal stresses (10 to 50 MPa), sliding velocity steps (3-100 μm/s) and slide-hold slide sequences (3 to 1000 s hold) under saturated conditions. Mechanical results demonstrate that both fault rocks and parent sediments are weaker than average geological materials (friction μ<<0.6) and have velocity-strengthening behavior because of the presence of phyllosilicate horizons. Fault rocks are

  3. Response of forearc crustal faults to the megathrust earthquake cycle: InSAR evidence from Mejillones Peninsula, Northern Chile

    NASA Astrophysics Data System (ADS)

    Shirzaei, M.; Bürgmann, R.; Oncken, O.; Walter, T. R.; Victor, P.; Ewiak, O.

    2012-06-01

    We report on a rare example of aseismic response of a creeping fault to the earthquake cycle of a nearby megathrust. Interferometric synthetic aperture radar (InSAR) is used to detect and analyze shallow creep of two crustal faults at Mejilones Peninsula, Northern Chile, located in the hanging wall of the 2007 Mw 7.7 Tocopilla subduction earthquake. We generate two independent time series of surface deformation spanning ∼3.5 yr of late interseismic and ∼1.5 yr early postseismic deformation associated with this event. The analysis reveals creep on the Mejillones fault as well as on a previously unmapped fault to the west of the Mejillones fault. The InSAR deformation maps and distributed slip models obtained from the data reveal that fault creep reversed between the interseismic and postseismic periods. Given the regional stress field perturbations due to interseismic and coseismic deformation, we argue that the observed shallow creep and its slip reversal are directly linked to the megathrust seismic cycle. Moreover, from similar eastward dips but opposite slip directions of the two faults, we infer that fault strength must be very low and that the kinematics is controlled by crustal flexure associated with the seismic cycle on the underlying megathrust.

  4. 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.

  5. Hardware Fault Simulator for Microprocessors

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

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

  6. 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.

  7. New insights into the tectonic evolution of the Boconó Fault, Mérida Andes, Venezuela

    NASA Astrophysics Data System (ADS)

    Backé, G.

    2006-12-01

    The Boconó fault is a major right-lateral strike-slip fault that cuts along strike the Mérida Andes in Venezuela. The uplift of this mountain range started in the Miocene as a consequence of the relative oblique convergence between two lithospheric units named the Maracaibo block to the northwest and the Guyana shield to the southeast. Deformation in the Mérida Andes is partitioned between a strike-slip component along the Boconó fault and shortening perpendicular to the belt. Distinctive features define the Boconó fault: it is shifted southward relative to the chain axis and it does not have a continuous and linear trace but is composed of several fault segments of different orientations striking N35°E to N65°E. Quaternary fault strike-slip motion has been evidenced by various independent studies. However, onset of the strike-slip motion, fault offset and geometry at depth remains a matter of debate. Our work, based on morphostructural analyses of satellite and digital elevation model imagery, provides new data on both the geometry and the tectonic evolution of this major structure. We argue that the Boconó fault affects only the upper crust and connects at depth to a décollement. Consequently, it can not be considered as a plate boundary. The Boconó fault does however form the boundary between two different tectonic areas in the central part of the Mérida Andes as revealed by the earthquake focal mechanisms. South of the Boconó fault, the focal mechanisms are mainly compressional and reverse oblique-slip in agreement with NW SE shortening in the foothills. North of the Boconó fault, extensional and strike-slip deformation dominates. Microtectonic measurements collected in the central part of the Boconó fault are characterized by polyphased tectonics. The dextral shearing along the fault is superimposed to reverse oblique-slip to reverse motion, showing that initiation of transcurrent movement is more likely to have occurred after a certain amount of

  8. Triggered dynamics in a model of different fault creep regimes

    PubMed Central

    Kostić, Srđan; Franović, Igor; Perc, Matjaž; Vasović, Nebojša; Todorović, Kristina

    2014-01-01

    The study is focused on the effect of transient external force induced by a passing seismic wave on fault motion in different creep regimes. Displacement along the fault is represented by the movement of a spring-block model, whereby the uniform and oscillatory motion correspond to the fault dynamics in post-seismic and inter-seismic creep regime, respectively. The effect of the external force is introduced as a change of block acceleration in the form of a sine wave scaled by an exponential pulse. Model dynamics is examined for variable parameters of the induced acceleration changes in reference to periodic oscillations of the unperturbed system above the supercritical Hopf bifurcation curve. The analysis indicates the occurrence of weak irregular oscillations if external force acts in the post-seismic creep regime. When fault motion is exposed to external force in the inter-seismic creep regime, one finds the transition to quasiperiodic- or chaos-like motion, which we attribute to the precursory creep regime and seismic motion, respectively. If the triggered acceleration changes are of longer duration, a reverse transition from inter-seismic to post-seismic creep regime is detected on a larger time scale. PMID:24954397

  9. 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.

  10. 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.

  11. 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.

  12. Aeromagnetic anomalies over faulted strata

    USGS Publications Warehouse

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

    2011-01-01

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

  13. 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

  14. 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

  15. Fault diagnosis of power systems

    SciTech Connect

    Sekine, Y. ); Akimoto, Y. ); Kunugi, M. )

    1992-05-01

    Fault diagnosis of power systems plays a crucial role in power system monitoring and control that ensures stable supply of electrical power to consumers. In the case of multiple faults or incorrect operation of protective devices, fault diagnosis requires judgment of complex conditions at various levels. For this reason, research into application of knowledge-based systems go an early start and reports of such systems have appeared in may papers. In this paper, these systems are classified by the method of inference utilized in the knowledge-based systems for fault diagnosis of power systems. The characteristics of each class and corresponding issues as well as the state-of-the-art techniques for improving their performance are presented. Additional topics covered are user interfaces, interfaces with energy management systems (EMS's), and expert system development tools for fault diagnosis. Results and evaluation of actual operation in the field are also discussed. Knowledge-based fault diagnosis of power systems will continue to disseminate.

  16. Finding Active Faults in a Glaciated and Forested Landscape: the Southern Whidbey Island Fault, Washington

    NASA Astrophysics Data System (ADS)

    Blakely, R. J.; Sherrod, B. L.; Wells, R. E.; Weaver, C. S.

    2004-12-01

    about 27 km of downtown Everett. Glacial deposits are slightly magnetic, and, in places, the magnetic anomaly is associated with topographic lineaments. Spectral analysis indicates, however, that the source of the anomaly extends to depths greater than 2 km and into Eocene sedimentary strata. Subtle scarps on Pleistocene surfaces are visible on high-resolution lidar topography at a number of locations along the aeromagnetic lineament. Collectively, the scarps are coincident with the aeromagnetic lineament and extend a total distance of 18 km. In the field, scarps exhibit 1 to 5 m of northeast-side-up offset. Two trenches were excavated across one of the lidar scarps during the summer of 2004. Both trenches showed evidence for folding, presumably above a buried reverse/oblique fault tip with at least 2 m of vertical offset. One trench also exposed a normal fault, although it was not possible to determine whether slip was caused by glacial or tectonic processes. The radiocarbon age of a folded, buried soil indicates that the earthquake occurred after 12 ka. Thus, the SWIF has produced at least two slip events in the Holocene, one occurring ˜3 ka on Whidbey Island and the other ˜12 ka on the Washington mainland.

  17. 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.

  18. Nonlinear Network Dynamics on Earthquake Fault Systems

    SciTech Connect

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

    2001-10-01

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

  19. Intramontane basin development related to contractional and extensional structure interaction at the termination of a major sinistral fault: The Huércal-Overa Basin (Eastern Betic Cordillera)

    NASA Astrophysics Data System (ADS)

    Pedrera, Antonio; Galindo-Zaldívar, Jesús; Tello, Alejandro; Marín-Lechado, Carlos

    2010-05-01

    Among the classical minor structural associations on the termination of transcurrent faults are horsetail splays formed by reverse, normal or strike-slip faults developing duplexes. However, temporal and spatial coexistence of contractional and extensional structures is very rarely documented. We discuss the relationships of contractional and extensional structures and associated sedimentary depocenters at the termination of a major strike-slip fault in the Eastern Betic Cordillera. Field mapping, kinematic fault analysis, paleostress determination and gravity prospecting in the Huércal-Overa Basin, at the southern termination of the NE-SW Alhama de Murcia transcurrent fault (AMF), are used to establish the relationships of tectonic structures and associated sedimentary depocenters. Here, ENE-WSW and WNW-ESE folds interact with two sets of normal faults having the same orientation as well as ENE-WSW reverse faults. Progressive unconformities associated with folds reveal that the beginning of the AMF activity occurred in the Tortonian. The folds progressively grew and rotated from ENE-WSW up to WNW-ESE close to the transcurrent fault. We propose that the development of the normal faults developed during short-term episodes characterized by vertical major stress axis and are, in turn, related to gravitational instability linked to the thickening of a crust relatively hot at depth. This setting may have become predominant in between the main activity, compressive pulses along transcurrent faults.

  20. Reverse Transfer in Australia

    ERIC Educational Resources Information Center

    Moodie, Gavin

    2004-01-01

    This article considers national Australian data on reverse transfer--the transfer of students from bachelor programs or higher to sub baccalaureate programs, institutions and sectors. It finds that previous studies have overstated the prevalence and perhaps also the significance of reverse transfer. The data are not good, but the best conclusion…

  1. Quantum reverse hypercontractivity

    SciTech Connect

    Cubitt, Toby; Kastoryano, Michael; Montanaro, Ashley; Temme, Kristan

    2015-10-15

    We develop reverse versions of hypercontractive inequalities for quantum channels. By generalizing classical techniques, we prove a reverse hypercontractive inequality for tensor products of qubit depolarizing channels. We apply this to obtain a rapid mixing result for depolarizing noise applied to large subspaces and to prove bounds on a quantum generalization of non-interactive correlation distillation.

  2. Justice and Reverse Discrimination.

    ERIC Educational Resources Information Center

    Goldman, Alan H.

    Defining reverse discrimination as hiring or admissions decisions based on normally irrelevant criteria, this book develops principles of rights, compensation, and equal opportunity applicable to the reverse discrimination issue. The introduction defines the issue and discusses deductive and inductive methodology as applied to reverse…

  3. Reverse Discrimination: Recent Cases.

    ERIC Educational Resources Information Center

    Steinhilber, August W.

    This paper discusses reverse discrimination cases with particular emphasis on Bakke v. Regents of University of California and those cases which preceded it. A brief history is given of court cases used by opponents and proponents in the discussion of reverse discrimination. Legal theory and a discussion of court cases that preceded Bakke follow.…

  4. Ultrasonic Time Reversal Mirrors

    NASA Astrophysics Data System (ADS)

    Fink, Mathias; Montaldo, Gabriel; Tanter, Mickael

    2004-11-01

    For more than ten years, time reversal techniques have been developed in many different fields of applications including detection of defects in solids, underwater acoustics, room acoustics and also ultrasound medical imaging and therapy. The essential property that makes time reversed acoustics possible is that the underlying physical process of wave propagation would be unchanged if time were reversed. In a non dissipative medium, the equations governing the waves guarantee that for every burst of sound that diverges from a source there exists in theory a set of waves that would precisely retrace the path of the sound back to the source. If the source is pointlike, this allows focusing back on the source whatever the medium complexity. For this reason, time reversal represents a very powerful adaptive focusing technique for complex media. The generation of this reconverging wave can be achieved by using Time Reversal Mirrors (TRM). It is made of arrays of ultrasonic reversible piezoelectric transducers that can record the wavefield coming from the sources and send back its time-reversed version in the medium. It relies on the use of fully programmable multi-channel electronics. In this paper we present some applications of iterative time reversal mirrors to target detection in medical applications.

  5. Reversible Shape Memory

    NASA Astrophysics Data System (ADS)

    Zhou, Jing; Li, Qiaoxi; Turner, Sara; Brosnan, Sarah; Tippets, Cary; Carrillo, Jan-Michael; Nykypnachuk, Dmytro; Gang, Oleg; Dobrynin, Andrey; Lopez, Rene; Ashby, Valerie; Sheiko, Sergei

    2014-03-01

    Reversible shape memory has been achieved on various shapes, e.g. hairpin, origami, coil, robotic gripper and flow rate control device, allowing for multiple switching between encoded shapes without applying any external force. Also, the reversible photonic structure molded in dielectric elastomers has been designed. Maximum reversibility can be achieved by tuning the crosslinking density and the degree of crystallinity of semi-crystalline elastomers. Different crystallization protocols including isothermal and cooling crystallization have been applied to develop a universal picture integrating different shape memory (SM) behaviors: conventional one-way SM, two-way reversible SM, and one-way reversible SM. Acknowledge financial support from the NSF DMR-1122483, DMR- 1004576, and DMR-1206957.

  6. High Resolution Seismic Reflection Imaging of the Southern Whidbey Island fault, Northwest Washington State

    NASA Astrophysics Data System (ADS)

    Pape, K. M.; Liberty, L. M.; Pratt, T. L.

    2006-12-01

    The Southern Whidbey Island fault (SWIF) is an active fault between the Seattle and Everett Basins in northwest Washington State. Marine seismic and geologic data characterize the SWIF as sub-parallel, northwest trending reverse faults that may extend over a 100 km distance and may be capable of producing M 7 or greater earthquakes. We acquired two land-based seismic transects crossing LIDAR and magnetic lineaments associated with the SWIF near Woodinville, WA, to relate surface scarps to subsurface structures and to characterize deformation in the upper 0.5 km of strata. Nearby borehole data place Pleistocene and younger deposits at depths less than 0.2 km, with Tertiary and older strata identified below. The 2 km, north-south Crystal Lake transect crosses the surface locations of LIDAR and magnetic lineaments and shows reverse faulting that offsets Tertiary and younger strata in a zone that extends more than 1.25 km. In contrast, we interpret relatively undeformed, flat lying Tertiary strata at depths of 0.1 to 0.2 km south of the observed surface lineaments. In the 3 km, east-west Woodinville transect, we identify reverse faulting and folding that forms a small 0.75 km-wide graben within a broader deformation zone. These anomalies are on strike with the LIDAR and magnetic lineaments identified near Crystal Lake. The presence of a small graben in the SWIF is consistent with models that hypothesize strike-slip motion on the fault system, with curvature of adjacent fault strands forming a small pull-apart basin. Our observations suggest that other magnetic lineaments in the region also are likely associated with fault strands. We acquired three additional transects upwards of 30 km southeast of Woodinville to determine whether the SWIF extends beyond surface lineaments and potentially merging with the Seattle Fault. Our preliminary analysis shows faulted Tertiary and younger strata on these profiles. If the observed fault strands on these transects are related to

  7. Focal mechanisms and the state of stress on the San Andreas Fault in southern California

    NASA Astrophysics Data System (ADS)

    Jones, Lucile M.

    1988-08-01

    Focal mechanisms have been determined from P wave first motion polarities for 138 small to moderate (2.6 ≤ M ≤ 4.3) earthquakes that occurred within 10 km of the surface trace of the San Andreas fault in southern California between 1978 and 1985. On the basis of these mechanisms the southern San Andreas fault has been divided into five segments with different stress regimes. Earthquakes in the Fort Tejon segment show oblique reverse sup on east-west and northwest striking faults. The Mojave segment has earthquakes with oblique reverse and right-lateral strikesup motion on northwest strikes. The San Bernardino segment has normal faulting earthquakes on north-south striking planes, while the Banning segment has reverse, strike-sup, and normal faulting events all occurring in the same area. The earthquakes in the Indio segment show strike-slip and oblique normal faulting on northwest to north-south striking planes. These focal mechanism data have been inverted to determine how the stresses acting on the San Andreas fault in southern California vary with position along strike of the fault. One of the principal stresses is vertical in all of the regions. The vertical stress is the minimum principal stress in Fort Tejon and Mojave, the intermediate principal stress in Banning and Indio, and the maximum principal stress in San Bernardino. The orientations of the horizontal principal stresses also vary between the regions. The trend of the maximum horizontal stress rotates over 35°, from N15°W at Fort Tejon to N20° at Indio. Except for the San Bernardino segment, the trend of the maximum horizontal stress is at a constant angle of about 65° to the local strike of the San Andreas fault, implying a weak fault. The largest change in the present stress state occurs at the end of the rupture zone of the 1857 Fort Tejon earthquake. It appears that the 1857 rupture ended when it propagated into an area of low stress amplitude, possibly caused by the 15° angle between the

  8. 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.

  9. Dextral Strike-Slip Faulting Along the Early Permian Margin of Pangaea (Eastern Australia) and Implications for Oroclinal Bending

    NASA Astrophysics Data System (ADS)

    Rosenbaum, G.; Uysal, I. T.; Babaahmadi, A.

    2014-12-01

    The breakup of the Pangaean supercontinent was one of the most significant events that affected Phanerozoic global tectonics. Heralding this process, and following the Carboniferous maximum stage of continental assembly, was a period in which the southern part of Pangaea (Gondwana) was subjected to a counterclockwise rotation relative to Laurasia. According to tectonic reconstructions, dextral wrench faulting and oroclinal bending in Varsican Europe and eastern Gondwana accompanied this rotation, but direct evidence for dextral strike-slip faulting in the eastern Gondwanan margin has hitherto not been reported. Here we show evidence from a well-preserved fault zone in eastern Australia (Red Rock fault zone), which occurs along the eastern limb of the Z-shaped Texas/Coffs Harbour orocline. Structural observations show evidence for dextral strike-slip faulting, with a reverse kinematic component, along a sub-vertical fault plane oriented NNE-SSW. Direct geochronological data (Rb-Sr and Ar-Ar) from fault gouge samples associated with this fault zone indicate that brittle faulting occurred in the early-mid Permian (288-264 Ma). In addition, oxygen and hydrogen stable isotope geochemistry indicates that the origin of fluids that circulated in the fault zone was associated with a deep crustal source. These results are consistent with independent constraints on the timing of oroclinal bending, supporting the idea that dextral wrench faulting has directly contributed to the formation of the oroclines. We propose a kinematic model for the formation of the oroclines, attributing the early stage of oroclinal bending to subduction rollback and slab segmentation (at ~300-288 Ma) followed by a period of dextral wrench faulting at 288-264 Ma. In the context of Pangaea, our model suggests that the origin of oroclines along the rim of Gondwana was likely associated with bending in response to migrating plate boundaries, and a subsequent tightening of pre-existing curvatures by

  10. Constraints on the geometry of the Suasselkä post-glacial fault, northern Finland, based on reflection seismic imaging

    NASA Astrophysics Data System (ADS)

    Abdi, Amir; Heinonen, Suvi; Juhlin, Christopher; Karinen, Tuomo

    2015-05-01

    Unloading of the ice during the last glacial period in northern Fennoscandia is believed to have generated major faulting. These faults, often referred to as post-glacial faults, typically have clear surface exposures, but their geometry at depth is poorly known. In order to better understand the geometry at depth of the Suasselkä post-glacial fault in Finland, three high resolution 2D reflection seismic profiles over the fault were reprocessed. Their total profile length is about 60 km and they were acquired as part of a major effort in Finland to map the uppermost crust in mining areas. The reprocessing led to significantly improved images that could be used to map the fault at depth. Two approximately N-S striking profiles and one E-W striking profile were reprocessed. The different azimuths and the crooked nature of the profiles allowed the fault geometry to be relatively well constrained. Clear reflections from the fault, dipping towards the SE, can be traced from the shallow subsurface down to about 3 km. The strike and dip of two sets of dipping reflections in the stacked data along with geometrical constraints and cross-dip analysis give a consistent dip of about 35-45° towards the SE for the fault. The strike and dip vary from N55E with a dip of 35° in the east to a strike of N48E with a dip of 45° in the west. Existence of the two sets of reflections indicates that the fault surface is non-planar. Aside from allowing the geometry of the fault to be determined, the seismic data show a complex reflectivity pattern in the area and indications of both reverse and normal movement along fault planes with similar orientation to the Suasselkä post-glacial fault. These images can be used as a basis for better characterizing the 3D geology of the area.

  11. Applications of chaotic oscillator in machinery fault diagnosis

    NASA Astrophysics Data System (ADS)

    Li, Chongsheng; Qu, Liangsheng

    2007-01-01

    The forward detecting method is used to detect weak periodic signals by identifying the transformation of the chaotic oscillator from the chaotic state to the large-scale periodic state when a weak external periodic signal is applied. Based on the method above, in this paper, a similar method, which is devised in a reverse way, is presented. The method detects the change of a weak signal by identifying the transformation of the chaotic oscillator from the large-scale periodic state to the chaotic state when a weak external signal is applied. This paper discusses and summarizes the features and scopes of both methods in their application in the field of machinery fault diagnosis. Satisfactory results have been achieved when using both of them in the fault diagnosis of rolling bearings and automobile gearboxes. The paper also presents how to use symbol sequence statistics to automatically identify the state transformation of the chaotic oscillator.

  12. Arshan palaeoseismic feature of the Tunka fault (Baikal rift zone, Russia)

    NASA Astrophysics Data System (ADS)

    Smekalin, Oleg P.; Shchetnikov, Alexander A.; White, Dustin

    2013-01-01

    The traditional concept of the rift development of flank depressions in the Baikal rift zone is now doubted in view of some indicators for compression deformations identified by the seismogeological and geodetic methods. Besides, the paleoseismological investigations revealed seismogenic strike-slips and reverse faults in the Tunka fault zone that is a major structure-controlling element of the Tunka rift depression. However, a detailed study of the upslope-facing scarp in the Arshan paleoseismogenic structure zone has shown that its formation might be due to rift mechanism of basin formation. Age estimation has been made for the previously unknown pre-historic earthquake whose epicentral area coincides with the western flank of the Arshan paleoseismogenic structure. Judging from previously determined ages of paleoearthquakes, the mean recurrence period for faulting events on the central Tunka fault is 2780-3440 years.

  13. Fault Analysis in Solar Photovoltaic Arrays

    NASA Astrophysics Data System (ADS)

    Zhao, Ye

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

  14. Late Cretaceous and Cenozoic dynamics of the Bohemian Massif inferred from the paleostress history of the Lusatian Fault Belt

    NASA Astrophysics Data System (ADS)

    Coubal, Miroslav; Málek, Jiří; Adamovič, Jiří; Štěpančíková, Petra

    2015-07-01

    An analysis of fault-slip data from the Lusatian Fault Belt, limiting the Lusatian Block of the Bohemian Massif in the SW, yielded parameters of eight successive paleostress patterns, Late Cretaceous to Plio-Pleistocene in age. These patterns were linked with specific stages in fault kinematics and fault-belt deformation. They include (1) α1, NE- to NNE-directed compression in a reverse fault regime (σ3 vertical) associated with major thrusting and drag zone formation in the latest Cretaceous, preceded by pre-drag origin of deformation bands α0; (2) αβ1-2, WNW-directed extension associated with emplacement of polzenite-group volcanics (≈80-61 Ma) and influx of hydrothermal fluids, overlapping in time with α1; (3) α2, N-directed compression in a reverse fault regime, probably Paleocene in age, associated with thrusting and intensive shear faulting in adjacent parts of blocks; (4) αβ3, Early Oligocene W- to WNW-directed extension in a regime of strike-slip faulting (σ2 vertical), probably connected with an emplacement of phonolitic magmas and influx of hydrothermal fluids; (5) α3, NNW-directed compression associated with activation of transverse/oblique faults of the fault belt, close in age to αβ3 with unclear mutual superposition; (6) β, Late Oligocene-Early Miocene multi-stage N- to NE-directed extension in a normal fault regime, specific to the Bohemian Massif, responsible for downfaulting of the hangingwall block; (7) γ, Mid to Late Miocene NE-directed compression in a reverse fault regime associated with thrusting; (8) δ, Pliocene (to Pleistocene?) NW- to NNW-directed compression in a strike-slip regime, associated with transverse faulting in the fault belt. The identified paleostress patterns show a good correlation with the hitherto identified paleostress fields transmitted to the Alpine foreland and refine the temporal sequence of paleostress states, especially in the post-Lower Miocene period.

  15. 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.

  16. Holocene Fault Scarps and Shallow Magnetic Anomalies Along the Southern Whidbey Island Fault Zone Near Woodinville, Washington

    NASA Astrophysics Data System (ADS)

    Sherrod, B.; Blakely, R. J.; Weaver, C.; Kelsey, H. M.; Barnett, E.; Wells, R.

    2005-12-01

    The southern Whidbey Island fault zone (SWIFZ), mapped previously using borehole data, potential-field anomalies, and marine seismic-reflection surveys, consists of four sub-parallel, northwest-trending fault strands, extending ~100 km from near Vancouver Island to the Washington mainland. The SWIFZ has been hypothesized to extend southeastward beneath the mainland, making landfall between the cities of Seattle and Everett. Linear, low-amplitude aeromagnetic anomalies in this mainland region are on strike with the mapped portion of the SWIFZ and may indicate that the fault continues southeast. The Cottage Lake aeromagnetic lineament, is most prominent, extends at least 16 km and is approximately on strike with the SWIFZ on Whidbey Island. Glacial deposits are slightly magnetic in this region, as indicated by magnetic susceptibility measurements and a ground-magnetic survey, and, in places, the Cottage Lake aeromagnetic lineament is associated with topographic lineaments. Spectral analysis and modeling experiments indicate that the source of the Cottage Lake aeromagnetic lineament extends to depths greater than 2 km and probably into Eocene sedimentary strata. Coastal marsh stratigraphy, lidar mapping, and fault scarp excavations help define recent activity along the SWIFZ. Abrupt uplift at a coastal marsh on south-central Whidbey Island suggests that the SWIFZ experienced a MW 6.5 - 7.0 earthquake between 3200 and 2800 years B.P. Subtle scarps on Pleistocene surfaces are delineated by high-resolution lidar topography at a number of locations in the mainland region, often closely associated with aeromagnetic lineaments. In the field, scarps exhibit northeast-side-up vertical relief of 1 to 5 m. Four excavations across two lidar scarps show evidence for multiple folding and faulting events since deglaciation, most likely above buried reverse/oblique faults. One trench exposed a normal fault, although it was not possible to determine whether glacial or tectonism

  17. Transient Deformation at the Seismic-Aseismic Transition in a Mature Plate Boundary Fault Zone - New Zealand's Alpine Fault

    NASA Astrophysics Data System (ADS)

    Toy, V. G.; Norris, R. J.; Prior, D. J.

    2008-12-01

    During the seismic cycle, stresses and strain rates fluctuate in the viscously-deforming zones down-dip of large faults. These transient events produce geological records that can be preserved in exhumed fault zones that have experienced single ruptures (e.g. Sesia Zone, European Western Alps). On the other hand, in major faults that have not experienced a simple, single rupture history, coseismic structures are likely to be destroyed during subsequent cycles of postseismic creep. New Zealand's active Alpine Fault has likely experienced upwards of 20,000 Mw~8 earthquakes, on average one every 200-300 years, over the last ≥5 million years of dextral-reverse slip. Fault rocks generated during these events are exhumed in the hangingwall, exposing materials deformed throughout the seismogenic zone at the surface. We have recognised a structural record of transient events in these rocks that differs from that previously reported elsewhere. Mylonites were formed by viscous shearing of a metasedimentary protolith downdip of the seismogenic structure. Rheological models predict these mylonites should have passed through a crustal strength peak (τ ≥100 MPa) around the brittle-viscous transition. Immediately prior to passing through this transition, they should have developed a small recrystallised grainsize (~10-15μm) and a crystallographic preferred orientation (CPO) indicating slip on the basal system during quartz dislocation creep, as well as a retrograde greenschist-facies mineralogy. However, the high-strain mylonites preserve a large recrystallised grainsize (>~30μm), amphibolite-facies mineralogy and CPO characteristic of prism slip. This suggests they were not significantly deformed at temperatures below ~450°C, significantly above the lower temperature limit for quartz crystal-plasticity at steady-state strain rates in the fault zone Microstructural observations and textural data indicate variable deformation style through the seismic cycle. Large fault

  18. The Plio-Pleistocene evolution of the Southern Middle Atlas Fault Zone (SMAFZ) front of Morocco

    NASA Astrophysics Data System (ADS)

    Laville, E.; Delcaillau, B.; Charroud, M.; Dugué, O.; Ait Brahim, L.; Cattaneo, G.; Deluca, P.; Bouazza, A.

    2007-06-01

    The South Middle Atlas front constitutes a northeast-trending shear zone, located north of the Neogene Missour basin and east of the Taza Guercif basin. This paper analyses the Southern Middle Atlas Fault Zone (SMAFZ) deformation since the Pliocene. The set of structures observed suggests that reverse and thrust faulting along the central part of the SMAFZ are combined with left-lateral slip along N S striking faults of its south-western termination and right-lateral faulting along E NE striking faults of the east northeast termination. Thrusts and oblique thrust-related anticlines of the two lateral ramps partly accommodate north-west directed motion of the African plate. The Thrusts probably resulted from rejuvenation of Jurassic normal faults; they were active during the Upper Miocene Pliocene and the Pleistocene. The geometries of positive inversion structures and buttressing effects are clearly dependent on the geometry and sedimentology of the original basin-controlling fault system and on the presence of a décollement level. Field mapping is integrated with Landsat imagery and a digital elevation model to investigate the morphotectonic evolution of the south-eastern range front of the Middle Atlas. Geomorphological features provide significant information on the processes that govern lateral propagation of active anticlines. Both suggest that the deformation front may have been active since Pliocene.

  19. Structural Analysis of the Pärvie Fault in Northern Scandinavia

    NASA Astrophysics Data System (ADS)

    Baeckstroem, A.; Rantakokko, N.; Ask, M. V.

    2011-12-01

    The Pärvie fault is the largest known postglacial fault in the world with a length of about 160 km. The structure has a dominating fault scarp as its western perimeter but in several locations it is rather a system of several faults. The current fault scarps, mainly caused by reverse faulting, are on average, 10-15 m in height and are thought to have been formed during one momentous event near the end of the latest glaciation (the Weichselian, 9,500-115,000 BP ) (Lagerbäck & Sundh, 2008). This information has been learnt from studying deformation features in sediments from the latest glaciation. However, the fault is believed to have been formed as early as the Precambrian, and it has been reactivated repeatedly throughout its history. The earlier history of this fault zone is still largely unknown. Here we present a pre-study to the scientific drilling project "Drilling Active Faults in Northern Europe", that was submitted to the International Continental Scientific Drilling Program (ICDP) in 2009 (Kukkonen et al. 2010) with an ICDP-sponsored workshop in 2010 (Kukkonen et al. 2011). During this workshop a major issue to be addressed before the start of drilling was to reveal whether the fault scarps were formed by one big earthquake or by several small ones (Kukkonen et al. 2011). Initial results from a structural analysis by Riad (1990) have produced information of the latest kinematic event where it is suggested that the latest event coincides with the recent stress field, causing a transpressional effect. The geometrical model suggested for an extensive area of several fault scarps along the structure is the compressive tulip structure. In the southern part, where the fault dips steeply E, the structure is parallel to the foliation of the country rock and earlier breccias, thus indicating a dependence of earlier structures. Modelling of the stress field during the latest glaciation show that a reverse background stress field together with excess pore pressure

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

    PubMed

    Bilham, R; Bodin, P

    1992-10-01

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

  1. Reconsidering Fault Slip Scaling

    NASA Astrophysics Data System (ADS)

    Gomberg, J. S.; Wech, A.; Creager, K. C.; Obara, K.; Agnew, D. C.

    2015-12-01

    The scaling of fault slip events given by the relationship between the scalar moment M0, and duration T, potentially provides key constraints on the underlying physics controlling slip. Many studies have suggested that measurements of M0 and T are related as M0=KfT3 for 'fast' slip events (earthquakes) and M0=KsT for 'slow' slip events, in which Kf and Ks are proportionality constants, although some studies have inferred intermediate relations. Here 'slow' and 'fast' refer to slip front propagation velocities, either so slow that seismic radiation is too small or long period to be measurable or fast enough that dynamic processes may be important for the slip process and measurable seismic waves radiate. Numerous models have been proposed to explain the differing M0-T scaling relations. We show that a single, simple dislocation model of slip events within a bounded slip zone may explain nearly all M0-T observations. Rather than different scaling for fast and slow populations, we suggest that within each population the scaling changes from M0 proportional to T3 to T when the slipping area reaches the slip zone boundaries and transitions from unbounded, 2-dimensional to bounded, 1-dimensional growth. This transition has not been apparent previously for slow events because data have sampled only the bounded regime and may be obscured for earthquakes when observations from multiple tectonic regions are combined. We have attempted to sample the expected transition between bounded and unbounded regimes for the slow slip population, measuring tremor cluster parameters from catalogs for Japan and Cascadia and using them as proxies for small slow slip event characteristics. For fast events we employed published earthquake slip models. Observations corroborate our hypothesis, but highlight observational difficulties. We find that M0-T observations for both slow and fast slip events, spanning 12 orders of magnitude in M0, are consistent with a single model based on dislocation

  2. Rupture interaction with fault jogs

    NASA Astrophysics Data System (ADS)

    Sibson, Richard H.

    Propagation of moderate to large earthquake ruptures within major transcurrent fault systems is affected by their large-scale brittle infrastructure, comprising echelon segmentation and curvature of principal slip surfaces (PSS) within typically ˜1 km wide main fault zones. These PSS irregularities are classified into dilational and antidilational fault jogs depending on the tendency for areal increase or reduction, respectively, across the jog structures. High precision microearthquake studies show that the jogs often extend throughout the seismogenic regime to depths of around 10 km. On geomorphic evidence, the larger jogs may persist for periods >105 years. While antidilational jogs form obstacles to both short- and long-term displacements, dilational jogs appear to act as kinetic barriers capable of perturbing or arresting earthquake ruptures, but allowing time-dependent slip transfer. In the case of antidilational jogs slip transfer is accommodated by widespread subsidiary faulting, but for dilational jogs it additionally involves extensional fracture opening localized in the echelon stepover. In fluid-saturated crust, the rapid opening of linking extensional fracture systems to allow passage of earthquake ruptures is opposed by induced suctions which scale with the width of the jog. Rupture arrest at dilational jogs may then be followed by delayed slip transfer as fluid pressures reequilibrate by diffusion. Aftershock distributions associated with the different fault jogs reflect these contrasts in their internal structure and mechanical response.

  3. Abrupt along-strike change in tectonic style: San Andreas fault zone, San Francisco Peninsula

    USGS Publications Warehouse

    Zoback, M.L.; Jachens, R.C.; Olson, J.A.

    1999-01-01

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

  4. The growth of geological structures by repeated earthquakes: 2, Field examples of continental dip-slip faults

    USGS Publications Warehouse

    Stein, R.S.; King, G.C.P.; Rundle, J.B.

    1988-01-01

    A strong test of our understanding of the earthquake cycle is the ability to reproduce extant faultbounded geological structures, such as basins and ranges, which are built by repeated cycles of deformation. Three examples are considered for which the structure and fault geometry are well known: the White Wolf reverse fault in California, site of the 1952 Kern County M=7.3 earthquake, the Lost River normal fault in Idaho, site of the 1983 Borah Peak M=7.0 earthquake, and the Cricket Mountain normal fault in Utah, site of Quaternary slip events. Basin stratigraphy and seismic reflection records are used to profile the structure, and coseismic deformation measured by leveling surveys is used to estimate the fault geometry. To reproduce these structures, we add the deformation associated with the earthquake cycle (the coseismic slip and postseismic relaxation) to the flexure caused by the observed sediment load, treating the crust as a thin elastic plate overlying a fluid substrate. -from Authors

  5. Reversible shape memory

    NASA Astrophysics Data System (ADS)

    Sheiko, Sergei; Zhou, Jing; White, Sarah; Ashby, Valerie

    2012-02-01

    An ``Achilles' heel'' of shape memory materials is that shape transformations triggered by an external stimulus are usually irreversible. Here we present a new concept of reversible transitions between two well-defined shapes by controlling hierarchic crystallization of a dual-network elastomer. The reversibility was demonstrated for different types of shape transformations including rod bending, winding of a helical coil, and widening an aperture. The distinct feature of the reversible shape alterations is that both counter-shapes are infinitely stable at a temperature of exploitation. Shape reversibility is highly desirable property in many practical applications such as non-surgical removal of a previously inserted catheter and handfree wrapping up of an earlier unraveled solar sail on a space shuttle.

  6. Tubal ligation reversal

    MedlinePlus

    ... Fernandez H, Gervaise A. Tubal anastomosis after tubal sterilization: a review. Arch Gynecol Obstet . 2011 May;283( ... Berger GS, Zerden ML. Pregnancy success after hysteroscopic sterilization reversal. Obstet Gynecol . 2014 Dec;124(6):1183- ...

  7. Deformation pattern around the conjoining strike-slip fault systems in the Basin and Range, southeast Nevada: The role of strike-slip faulting in basin formation and inversion

    NASA Astrophysics Data System (ADS)

    Çakir, Mehmet; Aydin, Atilla; Campagna, David J.

    1998-06-01

    Within the extensional regime of the Basin and Range, strike-slip faults create a regional pattern of opposing sense of fault systems. The relationship between these faults and other deformational features nearby is enigmatic. This paper addresses a diverse assemblage of contractional and extensional structures reflecting local uplift and subsidence, respectively, at the junction of two large Neogene strike-slip faults in southeastern Nevada, the right-lateral Las Vegas Valley shear zone and the left-lateral Bitter Spring Valley fault of the Lake Mead fault system. First, a middle Miocene lacustrine carbonate basin, the Bitter Ridge-Lovell Wash carbonate basin, formed north of the strike-slip faults. Second, the lacustrine basin inverted locally, while sediments accumulated south of the strike-slip faults. Third, the study area was deformed by north-northeast trending, high-angle oblique faults with normal and left-slip components. The results, both from field observations and numerical modeling of the intersecting strike-slip faults, show that the Las Vegas Valley shear zone and the Bitter Spring Valley fault may have produced the basin in the north and its intense contractional deformation as well as the southward shift of deposition during the inversion event. We conclude that conjoining strike-slip fault systems can promote localized vertical tectonics and lead to basin formation and uplift right next to each other. Subsequent inversion of the earlier basinal deposits, however, requires a reversal in the sense of slip across the Las Vegas Valley shear zone and a change in the regional stress system.

  8. 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

  9. 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.

  10. 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.

  11. Coulomb stress change on surrounding faults by the January 12, 2010, Haiti earthquake

    NASA Astrophysics Data System (ADS)

    Symithe, S. J.; Calais, E.; Freed, A. M.; Haase, J. S.

    2011-12-01

    The M7 January 12, 2010, Haiti earthquake occurred on the previously unmapped Léogâne Fault, a transpressional fault located very close to the Enriquillo Plantain Garden Fault (EPGF), the major fault system and primary seismic hazard in southern Haiti. How the rupture of the Léogâne fault influenced stresses on the Enriquillo Fault - especially toward Port-au-Prince - as well as on other regional faults is critical to understanding how seismic hazard in this heavily populated region has been altered as a result of the devastating 2010 earthquake. We calculated Coulomb Failure Stress (CFS) changes in the region surrounding the M7 January 12, 2010, Haiti earthquake using dislocation theory, assuming elastic properties for the region. We considered two possible slip models, the simple single-fault slip model proposed by Calais et al. (2010) and the more complex model by Hayes et al. (2010), which involves three subfaults. We resolve CFS changes on the Léogâne rupture plane itself, as well as on regional faults such as the Enriquillo, Neiba-Matheux, and Trois Baies faults. We find that the aftershock distribution is well explained by CFS changes caused by the coseismic rupture, in particular the cluster of reverse faulting events to the west of the rupture, offshore, coincident with the Trois Baies fault. This fault therefore appears to have been triggered by the January 2010 event. The aftershock distribution in the rupture area clearly outlines the Léogâne fault (see Douilly et al., this meeting) but shows no clear evidence of activity on the other subfaults suggested by Hayes et al. (2010). Both slip models imply a ~1 bar increase of CFS bar on the Enriquillo fault to the west and east of the January 2010 rupture. For the Calais et al. (2010) model, CFS changes are higher to the east if the Enriquillo Fault is modeled with a dip of 65° and a rake 20°, as suggested by some geological observations, compared to a purely strike-slip vertical fault, as often

  12. Distribution of deformation in a dextral fault-tip damage zone revealed from neotectonic mapping and high-resolution ALSM topography

    NASA Astrophysics Data System (ADS)

    selander, J.; Oskin, M. E.

    2013-12-01

    warping accumulates ahead of the fault tip, followed by short-wavelength (0.25-1 km) folds associated with the leading edge of faulting in the damage zone. Faulting initiates as en-echelon reverse faults, evolving to dextral slip with accumulated displacement. From our analysis we conclude that not all strain in the GHF damage zone accumulated through surface rupturing earthquakes; rather a component is accumulated aseismically through permanent, non-elastic deformation of the surrounding crust.

  13. Giant rodlike reversed micelles

    SciTech Connect

    Yu, Z.J.; Neuman, R.D. )

    1994-05-04

    Herein we report that sodium bis(2-ethylhexyl)phosphate, which is similar in structure to the classical surfactant sodium bis(2-ethylhexyl)sulfosuccinate (AOT), forms very large rodlike reversed micelles and that their size can be even much larger if water is removed from the apolar solution. We further suggest that long-range electrostatic interactions are the primary driving force for the formation of giant reversed micelles. 19 refs., 3 figs.

  14. Approximate Entropy Based Fault Localization and Fault Type Recognition for Non-solidly Earthed Network

    NASA Astrophysics Data System (ADS)

    Pang, Qingle; Liu, Xinyun; Sun, Bo; Ling, Qunli

    2012-12-01

    For non-solidly earthed network, the fault localization of single phase grounding fault has been a problem. A novel fault localization and fault type recognition method of single phase grounding fault based on approximate entropy is presented. The approximate entropies of transient zero sequence current at both ends of healthy section are approximately equal, and the ratio is close to 1. On the contrary, the approximate entropies at both ends of fault section are different, and the ratio is far from 1. So, the fault section is located. At the same fault section, the smaller is the fault resistance, the larger is the approximate entropy of transient zero sequence current. According to the function between approximate entropy and fault resistance, the fault type is determined. The method has the advantages of transferring less data and unneeded synchronous sampling accurately. The simulation results show that the proposed method is feasible and accurate.

  15. 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

  16. Paleomagnetism of the Ocotillo Badlands, southern California, and implications for slip transfer through an antidilational fault jog

    NASA Astrophysics Data System (ADS)

    Brown, Norman N.; Fuller, Michael D.; Sibson, Richard H.

    1991-03-01

    The right-lateral Coyote Creek fault is the southernmost segment of the San Jacinto fault zone in California. At the Ocotillo Badlands, an anticlinorium of locally updomed material is exposed at a step-over between echelon segments of the fault. Here, uplift and deformation most probably result from multiple slip increments transferred across the antidilational fault jog, under the assumption that material away from the jog region deforms by rigid body translation. Within the 2 km wide fault jog, contraction has occurred by folding of the Quaternary sedimentary strata about east-west trending hinge lines. Structural analysis of this deformation shows that folding has accommodated ˜ 800 m of fault slip transferred through the antidilational jog. By comparison, total right slip on the Coyote Creek fault is 2.5 km, measured 25 km to the northwest at Coyote Ridge. A magnetostratigraphic study of the deformed strata was undertaken to determine the longevity of this fault discontinuity at the Ocotillo Badlands. The eroded core of the updomed material at the Ocotillo Badlands exposes a 325 m thick sequence of sedimentary rock, made up by the lacustrine Borrego Formation (˜ 200 m) and the overlying conglomeratic Ocotillo Formation (˜ 125 m). Stepwise thermal demagnetization of samples from the exposed strata suggests that the formation boundary also marks a magnetic polarity reversal, of reversed field to normal field as one travels upwards through the composite section. The inferred primary magnetization is probably produced by a detrital remanent magnetization (DRM) and is often overprinted with a weak, viscous present field component. Comparison with magnetostratigraphy of the Borrego Badlands 10 km to the northwest indicates that the reversal sampled is the onset of the Jaramillo event (0.97 Ma). The presence of a 20° angular unconformity within the upper portion of the exposed stratigraphy shows that deformation within the Ocotillo Badlands began during deposition

  17. 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.

  18. The Channel Islands Thrust Fault, Southern California: Structure at the Juncture Between the Western Transverse Ranges and the Continental Borderland

    NASA Astrophysics Data System (ADS)

    Fisher, M. A.; Langenheim, V. E.

    2004-12-01

    Potential-field data over the northern Channel Islands and Santa Barbara basin and seismic reflection data collected near these islands show the crustal structure near the tip of the Channel Island thrust fault. This fault dips north to underlie the Santa Barbara basin and is part of the regional fault system that separates the western Transverse Ranges from the California Continental Borderland. Our investigation focuses on Santa Cruz Island, where a local exposure of mainly Jurassic ophiolitic basement rocks includes the Willows Plutonic Complex. These mafic and ultramafic igneous rocks produce strong magnetic and gravity anomalies, showing that fragments of the Willows Plutonic Complex have been carried northwestward into or below the basin by sinistral translation of hanging-wall blocks in the thrust system. The potential-field anomalies indicate a cumulative left-lateral offset of about 20 km along what is probably the Santa Cruz Island fault. This fault is known from onshore trenching to be primarily a left-lateral strike-slip fault that was active during late Quaternary time. Seismic-reflection data show that where the Santa Cruz Island fault projects into the offshore a fault-bend fold deforms stratified rock in the Santa Barbara basin. Slip along this fault is partitioned into strike-slip and southwest-vergent reverse components. The Santa Cruz Island fault formed where structures of the California Borderland terminate to the northwest against the rocks that make up the northern Channel Islands. Structures developed at this termination may be similar to ones that formed where the Newport-Inglewood and the San Pedro Basin faults end to the northwest against the Santa Monica Mountains. These terminating faults pose a considerable earthquake hazard, and findings from the area of Santa Cruz Island may help elucidate this hazard.

  19. Faulting at Mormon Point, Death Valley, California: A low-angle normal fault cut by high-angle faults

    NASA Astrophysics Data System (ADS)

    Keener, Charles; Serpa, Laura; Pavlis, Terry L.

    1993-04-01

    New geophysical and fault kinematic studies indicate that late Cenozoic basin development in the Mormon Point area of Death Valley, California, was accommodated by fault rotations. Three of six fault segments recognized at Mormon Point are now inactive and have been rotated to low dips during extension. The remaining three segments are now active and moderately to steeply dipping. From the geophysical data, one active segment appears to offset the low-angle faults in the subsurface of Death Valley.

  20. Complex faulting in the Quetta Syntaxis: fault source modeling of the October 28, 2008 earthquake sequence in Baluchistan, Pakistan, based on ALOS/PALSAR InSAR data

    NASA Astrophysics Data System (ADS)

    Usman, Muhammad; Furuya, Masato

    2015-09-01

    The Quetta Syntaxis in western Baluchistan, Pakistan, is the result of an oroclinal bend of the western mountain belt and serves as a junction for different faults. As this area also lies close to the left-lateral strike-slip Chaman fault, which marks the boundary between the Indian and Eurasian plates, the resulting seismological behavior of this regime is very complex. In the region of the Quetta Syntaxis, close to the fold and thrust belt of the Sulaiman and Kirthar Ranges, an earthquake with a magnitude of 6.4 (Mw) occurred on October 28, 2008, which was followed by a doublet on the very next day. Six more shocks associated with these major events then occurred (one foreshock and five aftershocks), with moment magnitudes greater than 4. Numerous researchers have tried to explain the source of this sequence based on seismological, GPS, and Environmental Satellite (ENVISAT)/Advanced Synthetic Aperture Radar (ASAR) data. Here, we used Advanced Land Observing Satellite (ALOS)/Phased Array-type L-band Synthetic Aperture Radar (PALSAR) InSAR data sets from both ascending and descending orbits that allow us to more completely detect the deformation signals around the epicentral region. The results indicated that the shock sequence can be explained by two right-lateral and two left-lateral strike-slip faults that also included reverse slip. The right-lateral faults have a curved geometry. Moreover, whereas previous studies have explained the aftershock crustal deformation with a different fault source, we found that the same left-lateral segment of the conjugate fault was responsible for the aftershocks. We thus confirmed the complex surface deformation signals from the moderate-sized earthquake. Intra-plate crustal bending and shortening often seem to be accommodated as conjugate faulting, without any single preferred fault orientation. We also detected two possible landslide areas along with the crustal deformation pattern.

  1. On thermodynamic and microscopic reversibility

    SciTech Connect

    Crooks, Gavin E.

    2011-07-12

    The word 'reversible' has two (apparently) distinct applications in statistical thermodynamics. A thermodynamically reversible process indicates an experimental protocol for which the entropy change is zero, whereas the principle of microscopic reversibility asserts that the probability of any trajectory of a system through phase space equals that of the time reversed trajectory. However, these two terms are actually synonymous: a thermodynamically reversible process is microscopically reversible, and vice versa.

  2. Maximum Magnitude in Relation to Mapped Fault Length and Fault Rupture

    NASA Astrophysics Data System (ADS)

    Black, N.; Jackson, D.; Rockwell, T.

    2004-12-01

    Earthquake hazard zones are highlighted using known fault locations and an estimate of the fault's maximum magnitude earthquake. Magnitude limits are commonly determined from fault geometry, which is dependent on fault length. Over the past 30 years it has become apparent that fault length is often poorly constrained and that a single event can rupture across several individual fault segments. In this study fault geometries are analyzed before and after several moderate to large magnitude earthquakes to determine how well fault length can accurately assess seismic hazard. Estimates of future earthquake magnitudes are often inferred from prior determinations of fault length, but use magnitude regressions based on rupture length. However, rupture length is not always limited to the previously estimated fault length or contained on a single fault. Therefore, the maximum magnitude for a fault may be underestimated, unless the geometry and segmentation of faulting is completely understood. This study examines whether rupture/fault length can be used to accurately predict the maximum magnitude for a given fault. We examine earthquakes greater than 6.0 that occurred after 1970 in Southern California. Geologic maps, fault evaluation reports, and aerial photos that existed prior to these earthquakes are used to obtain the pre-earthquake fault lengths. Pre-earthquake fault lengths are compared with rupture lengths to determine: 1) if fault lengths are the same before and after the ruptures and 2) to constrain the geology and geometry of ruptures that propagated beyond the originally recognized endpoints of a mapped fault. The ruptures examined in this study typically follow one of the following models. The ruptures are either: 1) contained within the dimensions of the original fault trace, 2) break through one or both end points of the originally mapped fault trace, or 3) break through multiple faults, connecting segments into one large fault line. No rupture simply broke a

  3. 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.

  4. 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.

  5. 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.

  6. Solar Dynamic Power System Fault Diagnosis

    NASA Technical Reports Server (NTRS)

    Momoh, James A.; Dias, Lakshman G.

    1996-01-01

    The objective of this research is to conduct various fault simulation studies for diagnosing the type and location of faults in the power distribution system. Different types of faults are simulated at different locations within the distribution system and the faulted waveforms are monitored at measurable nodes such as at the output of the DDCU's. These fault signatures are processed using feature extractors such as FFT and wavelet transforms. The extracted features are fed to a clustering based neural network for training and subsequent testing using previously unseen data. Different load models consisting of constant impedance and constant power are used for the loads. Open circuit faults and short circuit faults are studied. It is concluded from present studies that using features extracted from wavelet transforms give better success rates during ANN testing. The trained ANN's are capable of diagnosing fault types and approximate locations in the solar dynamic power distribution system.

  7. Fault seals in oil fields in Nevada

    SciTech Connect

    Foster, N.H.; Veal, H.K.; Bortz, L.C.

    1987-08-01

    Faults forms seals for oil accumulations in the Eagle Springs, Trap Spring, and Blackburn fields, and probably in the Grant Canyon field, in Nevada. The main boundary fault on the east side of the Pine Valley graben forms a seal in the Blackburn field. A fault on the west side of the trap Spring field forms a seal. In Grant Canyon field, it is interpreted that the main boundary fault on the east side of the Railroad Valley graben forms a seal. Calcite is deposited by hot spring activity, plugging up many fault zones and, in some cases, forming seals. Some fault zones have calcite mineralization up to several thousand feet wide. Within the Eagle Springs field on the east side of the Railroad Valley graben, a northeast-trending fault separates oil accumulations with different oil-water contacts. This separation indicates that the fault forms at least a partial seal within the accumulation.

  8. 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.

  9. High-resolution seismic reflection profiling of the Santa Monica Fault Zone, West Los Angeles, California

    USGS Publications Warehouse

    Dolan, J.F.; Pratt, T.L.

    1997-01-01

    High-resolution seismic reflection data obtained across the Santa Monica fault in west Los Angeles reveal the near-surface geometry of this active, oblique-reverse-left-lateral fault. Although near-surface fault dips as great as 55?? cannot be ruled out, we interpret the fault to dip northward at 30?? to 35?? in the upper few hundred meters, steepening to ???65?? at 1 to 2 km depth. A total of ???180 m of near-field thrust separation (fault slip plus drag folding) has occurred on the fault since the development of a prominent erosional surface atop ???1.2 Ma strata. In the upper 20 to 40 m strain is partitioned between the north-dipping main thrust strand and several closely spaced, near-vertical strike-slip faults observed in paleoseismologic trenches. The main thrust strand can be traced to within 20 m of the ground surface, suggesting that it breaks through to the surface in large earthquakes. Uplift of a ???50,000-year-old alluvial fan surface indicates a short-term, dip-slip rate of ???0.5 mm/yr, similar to the ???0.6 mm/yr dip-slip rate derived from vertical separation of the oxygen isotope stage 5e marine terrace 3 km west of the study site. If the 0.6 mm/yr minimum, dip-slip-only rate characterizes the entire history of the fault, then the currently active strand of the Santa Monica fault probably began moving within the past ???300,000 years. Copyright 1997 by the American Geophysical Union.

  10. Optimally oriented ``fault-valve'' thrusts: Evidence for aftershock-related fluid pressure pulses?

    NASA Astrophysics Data System (ADS)

    Micklethwaite, S.

    2008-04-01

    A thrust-vein network from the Triumph gold deposit, Western Australia, is explained in terms of an extremely high rate of fluid-pressure increase, prior to failure, relative to the rate of stress increase. The thrust fault is a small-displacement fault characterized by a thick, fault-parallel shear vein, plus multiple low-angle extension veins, with orientations that demonstrate the thrust was optimally oriented relative to the locally imposed crustal stresses. Large extension veins have irregular margins, are dominantly composed of coarse milky quartz with no obvious laminations or solid inclusion trails, and are regularly spaced along the thrust (1-2 m). The fault-vein geometries indicate the Triumph thrust is a rare candidate for "fault-valve" failure of an optimally oriented thrust, and it is possible the structure formed in a small number of failure events, during load weakening of the thrust. An analysis using the Coulomb criterion shows that load weakening of a thrust occurs when fluid pressure increases relative to tectonic stress by a factor dependent on the orientation of the thrust. Thrust and reverse faults in dry crust load strengthen prior to failure, but the poroelastic behavior of sealed, fluid-saturated crust is enough to induce load weakening in compressive environments; thus poroelastic load weakening is expected to be an important failure mechanism in hydrothermal environments. However, in the case of the Triumph thrust, dilatant shear failure necessitates a fluid pressure increase which is an order of magnitude larger still. The observations and results are consistent with a pulse of high fluid pressure migrating up through fault or fracture networks that have elevated permeability relative to the wall rock, under conditions of transiently low differential stress. Fluid pressure differences resulted between the fault and wall rock, leading to extension fracture and fault failure. Such conditions may occur when adjacent large earthquakes induce

  11. Flexure and faulting of sedimentary host rocks during growth of igneous domes, Henry Mountains, Utah

    USGS Publications Warehouse

    Jackson, M.D.; Pollard, D.D.

    1990-01-01

    A sequence of sedimentary rocks about 4 km thick was bent, stretched and uplifted during the growth of three igneous domes in the southern Henry Mountains. Mount Holmes, Mount Ellsworth and Mount Hillers are all about 12 km in diameter, but the amplitudes of their domes are about 1.2, 1.85 and 3.0 km, respectively. These mountains record successive stages in the inflation of near-surface diorite intrusions that are probably laccolithic in origin. The host rocks deformed along networks of outcrop-scale faults, or deformation bands, marked by crushed grains, consolidation of the porous sandstone and small displacements of sedimentary beds. Zones of deformation bands oriented parallel to the beds and formation contacts subdivided the overburden into thin mechanical layers that slipped over one another during doming. Measurements of outcrop-scale fault populations at the three mountains reveal a network of faults that strikes at high angles to sedimentary beds which themselves strike tangentially about the domes. These faults have normal and reverse components of slip that accommodated bending and stretching strains within the strata. An early stage of this deformation is displayed at Mount Holmes, where states of stress computed from three fault samples correlate with the theoretical distribution of stresses resulting from bending of thin, circular, elastic plates. Field observations and analysis of frictional driving stresses acting on horizontal planes above an opening-mode dislocation, as well as the paleostress analysis of faulting, indicate that bedding-plane slip and layer flexure were important components of the early deformation. As the amplitude of doming increased, radial and circumferential stretching of the strata and rotation of the older faults in the steepening limbs of the domes increased the complexity of the fault patterns. Steeply-dipping, map-scale faults with dip-slip displacements indicate a late-stage jostling of major blocks over the central

  12. The 2010 Haiti earthquake: A complex fault pattern constrained by seismologic and tectonic observations

    NASA Astrophysics Data System (ADS)

    Mercier de Lépinay, Bernard; Deschamps, Anne; Klingelhoefer, Frauke; Mazabraud, Yves; Delouis, Bertrand; Clouard, Valérie; Hello, Yann; Crozon, Jacques; Marcaillou, Boris; Graindorge, David; Vallée, Martin; Perrot, Julie; Bouin, Marie-Paule; Saurel, Jean-Marie; Charvis, Philippe; St-Louis, Mildor

    2011-11-01

    After the January 12, 2010, Haiti earthquake, we deployed a mainly offshore temporary network of seismologic stations around the damaged area. The distribution of the recorded aftershocks, together with morphotectonic observations and mainshock analysis, allow us to constrain a complex fault pattern in the area. Almost all of the aftershocks have a N-S compressive mechanism, and not the expected left-lateral strike-slip mechanism. A first-order slip model of the mainshock shows a N264°E north-dipping plane, with a major left-lateral component and a strong reverse component. As the aftershock distribution is sub-parallel and close to the Enriquillo fault, we assume that although the cause of the catastrophe was not a rupture along the Enriquillo fault, this fault had an important role as a mechanical boundary. The azimuth of the focal planes of the aftershocks are parallel to the north-dipping faults of the Transhaitian Belt, which suggests a triggering of failure on these discontinuities. In the western part, the aftershock distribution reflects the triggering of slip on similar faults, and/or, alternatively, of the south-dipping faults, such the Trois-Baies submarine fault. These observations are in agreement with a model of an oblique collision of an indenter of the oceanic crust of the Southern Peninsula and the sedimentary wedge of the Transhaitian Belt: the rupture occurred on a wrench fault at the rheologic boundary on top of the under-thrusting rigid oceanic block, whereas the aftershocks were the result of the relaxation on the hanging wall along pre-existing discontinuities in the frontal part of the Transhaitian Belt.

  13. Interseismic deformation and moment deficit along the Manila subduction zone and the Philippine Fault system

    NASA Astrophysics Data System (ADS)

    Hsu, Y. J.; Yu, S. B.; Loveless, J. P.; Bacolcol, T.; Woessner, J.; Solidum, R., Jr.

    2015-12-01

    The Sunda plate converges obliquely with the Philippine Sea plate with a rate of ~100 mm/yr and results in the sinistral slip along the 1300 km-long Philippine fault. Using GPS data from 1998 to 2013 as well as a block modeling approach, we decompose the crustal motion into multiple rotating blocks and elastic deformation associated with fault slip at block boundaries. Our preferred model composed of 8 blocks, produces a mean residual velocity of 3.4 mm/yr at 93 GPS stations. Estimated long-term slip rates along the Manila subduction zone show a gradual southward decrease from 66 mm/yr at the northwest tip of Luzon to 60 mm/yr at the southern portion of the Manila Trench. We infer a low coupling fraction of 11% offshore northwest Luzon and a coupling fraction of 27% near the subduction of Scarborough Seamount. The accumulated strain along the Manila subduction zone at latitudes 15.5°~18.5°N could be balanced by earthquakes with composite magnitudes of Mw 8.7 and Mw 8.9 based on a recurrence interval of 500 years and 1000 years, respectively. Estimates of sinistral slip rates on the major splay faults of the Philippine fault system in central Luzon increase from east to west: sinistral slip rates are 2 mm/yr on the Dalton fault, 8 mm/yr on the Abra River fault, and 12 mm/yr on the Tubao fault. On the southern segment of the Philippine fault (Digdig fault), we infer left-lateral slip of ~20 mm/yr. The Vigan-Aggao fault in northwest Luzon exhibits significant reverse slip of up to 31 mm/yr, although deformation may be distributed across multiple offshore thrust faults. On the Northern Cordillera fault, we calculate left-lateral slip of ~7 mm/yr. Results of block modeling suggest that the majority of active faults in Luzon are fully locked to a depth of 15-20 km. Inferred moment magnitudes of inland large earthquakes in Luzon fall in the range of Mw 7.0-7.5 based on a recurrence interval of 100 years. Using the long-term plate convergence rate between the Sunda plate

  14. Time-Reversal Study of the Hemet (CA) Tremor Source

    NASA Astrophysics Data System (ADS)

    Larmat, C. S.; Johnson, P. A.; Guyer, R. A.

    2010-12-01

    Since its first observation by Nadeau & Dolenc (2005) and Gomberg et al. (2008), tremor along the San Andreas fault system is thought to be a probe into the frictional state of the deep part of the fault (e.g. Shelly et al., 2007). Tremor is associated with slow, otherwise deep, aseismic slip events that may be triggered by faint signals such as passing waves from remote earthquakes or solid Earth tides.Well resolved tremor source location is key to constrain frictional models of the fault. However, tremor source location is challenging because of the high-frequency and highly-scattered nature of tremor signal characterized by the lack of isolated phase arrivals. Time Reversal (TR) methods are emerging as a useful tool for location. The unique requirement is a good velocity model for the different time-reversed phases to arrive coherently onto the source point. We present results of location for a tremor source near the town of Hemet, CA, which was triggered by the 2002 M 7.9 Denali Fault earthquake (Gomberg et al., 2008) and by the 2009 M 6.9 Gulf of California earthquake. We performed TR in a volume model of 88 (N-S) x 70 (W-E) x 60 km (Z) using the full-wave 3D wave-propagation package SPECFEM3D (Komatitsch et al., 2002). The results for the 2009 episode indicate a deep source (at about 22km) which is about 4km SW the fault surface scarp. We perform STA/SLA and correlation analysis in order to have independent confirmation of the Hemet tremor source. We gratefully acknowledge the support of the U. S. Department of Energy through the LANL/LDRD Program for this work.

  15. Depth segmentation of fault slip: deep rupture in the 2011 Van Earthquake leaves shallow hazard

    NASA Astrophysics Data System (ADS)

    Elliott, J. R.; Copley, A.; Holley, R.; Scharer, K.; Parsons, B.

    2013-12-01

    We use InSAR, body-wave seismology, satellite imagery and field observations to constrain the fault parameters of the Mw 7.1 2011 Van (Eastern Turkey) reverse-slip earthquake, in the Turkish-Iranian Plateau. Distributed slip models from elastic dislocation modelling of the InSAR surface displacements from ENVISAT and COSMO-SkyMed interferograms indicate up to 9 m of reverse and oblique slip on a pair of en echelon NW 40-54 degree dipping fault planes which have surface extensions projecting to just 10 km north of the city of Van. The slip remained buried and is relatively deep, with a centroid depth of 14 km, and the rupture reaching only within 8--9 km of the surface, consistent with the lack of significant ground rupture. The up-dip extension of this modelled WSW-striking fault plane coincides with field observations of weak ground deformation seen on the western of the two fault segments, and has a dip consistent with that seen at the surface in fault gouge exposed in Quaternary sediments. No significant coseismic slip is found in the upper 8 km of the crust above the main slip patches, except for a small region on the eastern segment potentially resulting from the Mw 5.9 aftershock the same day. We perform extensive resolution tests on the data to confirm the robustness of the observed slip deficit in the shallow crust. We resolve a steep gradient in displacement at the point where the planes of the two fault segments ends are inferred to abut at depth, possibly exerting some structural control on rupture extent. This leaves an unruptured up-dip fault width of 8-11. Given that the surface trace of the fault is clearly visible in the geomorphology of the mountain range to the north of Van, and that fault gouge was found in Quaternary sediments at the surface, it is very likely that the upper portion of the crust is seismogenic. A rupture along a similar fault length of 30 km across the remaining unruptured fault width of 10 km, with a similar average slip of 3 m

  16. Investigation of the San Gabriel Fault in the Vicinity of Pyramid and Castaic Dams, Los Angeles County, California: Geologic and Seismologic Constraints from Existing

    NASA Astrophysics Data System (ADS)

    Pearce, J. T.; Turner, J. P.; O'Connell, D. R.; Hoirup, D. F.; Barry, G.; Glick, F.

    2012-12-01

    Pyramid and Castaic Dams are in an active transpressional deformation zone between the San Gabriel and San Andreas faults. The San Gabriel fault is ~3 km west of both dams, and is an ~80-km long structure. The fault plane geometry exerts a strong control on the calculated ground motion at the dam sites. Geologic studies have characterized the fault activity, geometry, and sense of displacement along the southern San Gabriel fault sections, (i.e., Honor Rancho, Newhall sections), whereas there is more uncertainty along the northern San Gabriel fault section (i.e., Palomas section). In particular, the dip direction and angle of the Palomas section at seismogenic depths are poorly constrained. Existing parameterizations of the Palomas section of the San Gabriel fault geometry range from near vertical orientation with strike-slip displacement to about 60 degree northeast dip with reverse displacement. To better assess the geometry of the San Gabriel fault at seismogenic depths (>5 km), we analyzed existing published oil well logs, available seismicity data, geologic maps, and current fault mapping. Spatial analysis of the seismicity data showed diffuse hypocentral trends that defied discrete fault plane identification. Analyses of focal mechanism solutions indicate fault strike directions in the west-northwest directions, discordant with the strike of the San Gabriel fault near Pyramid Dam. The focal mechanisms better indicate slip transfer to splay structures such as the Holser, Del Valle, and Santa Susana faults that sole into the active San Cayetano fault system to the west. Existing data do not provide sufficient information to refute an easterly dipping San Gabriel fault plane, nor do the data preclude a vertical to near-vertical orientation of the fault near Pyramid Dam. Based on apparent non-deformation of the Pliocene Hungry Valley Formation, the Palomas section of the fault has been proposed as inactive. This study identifies apparent undeformed Quaternary

  17. Implementing fault-tolerant sensors

    NASA Technical Reports Server (NTRS)

    Marzullo, Keith

    1989-01-01

    One aspect of fault tolerance in process control programs is the ability to tolerate sensor failure. A methodology is presented for transforming a process control program that cannot tolerate sensor failures to one that can. Additionally, a hierarchy of failure models is identified.

  18. Cell boundary fault detection system

    DOEpatents

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

    2011-04-19

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

  19. 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.

  20. Reversible collisionless magnetic reconnection

    SciTech Connect

    Ishizawa, A.; Watanabe, T.-H.

    2013-10-15

    Reversible magnetic reconnection is demonstrated for the first time by means of gyrokinetic numerical simulations of a collisionless magnetized plasma. Growth of a current-driven instability in a sheared magnetic field is accompanied by magnetic reconnection due to electron inertia effects. Following the instability growth, the collisionless reconnection is accelerated with development of a cross-shaped structure of current density, and then all field lines are reconnected. The fully reconnected state is followed by the secondary reconnection resulting in a weakly turbulent state. A time-reversed simulation starting from the turbulent state manifests that the collisionless reconnection process proceeds inversely leading to the initial state. During the reversed reconnection, the kinetic energy is reconverted into the original magnetic field energy. In order to understand the stability of reversed process, an external perturbation is added to the fully reconnected state, and it is found that the accelerated reconnection is reversible when the deviation of the E × B streamlines due to the perturbation is comparable with or smaller than a current layer width.

  1. FAULT & COORDINATION STUDY FOR T PLANT COMPLEX

    SciTech Connect

    MCDONALD, G.P.; BOYD-BODIAU, E.A.

    2004-09-01

    A short circuit study is performed to determine the maximum fault current that the system protective devices, transformers, and interconnections would he subject to in event of a three phase, phase-to-phase, or phase-to-ground fault. Generally, the short circuit study provides the worst case fault current levels at each bus or connection point of the system.

  2. 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.

  3. 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).

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

    NASA Astrophysics Data System (ADS)

    Solum, John G.; Davatzes, Nicholas C.; Lockner, David A.

    2010-12-01

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

  5. Fault tolerant software modules for SIFT

    NASA Technical Reports Server (NTRS)

    Hecht, M.; Hecht, H.

    1982-01-01

    The implementation of software fault tolerance is investigated for critical modules of the Software Implemented Fault Tolerance (SIFT) operating system to support the computational and reliability requirements of advanced fly by wire transport aircraft. Fault tolerant designs generated for the error reported and global executive are examined. A description of the alternate routines, implementation requirements, and software validation are included.

  6. 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...

  7. 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...

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. 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...

  13. 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...

  14. 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...

  15. 40 CFR 258.13 - Fault areas.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Fault areas. 258.13 Section 258.13... SOLID WASTE LANDFILLS Location Restrictions § 258.13 Fault areas. (a) New MSWLF units and lateral expansions shall not be located within 200 feet (60 meters) of a fault that has had displacement in...

  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. 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...

  19. 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...

  20. 40 CFR 258.13 - Fault areas.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Fault areas. 258.13 Section 258.13... SOLID WASTE LANDFILLS Location Restrictions § 258.13 Fault areas. (a) New MSWLF units and lateral expansions shall not be located within 200 feet (60 meters) of a fault that has had displacement in...

  1. 40 CFR 258.13 - Fault areas.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 26 2012-07-01 2011-07-01 true Fault areas. 258.13 Section 258.13... SOLID WASTE LANDFILLS Location Restrictions § 258.13 Fault areas. (a) New MSWLF units and lateral expansions shall not be located within 200 feet (60 meters) of a fault that has had displacement in...

  2. 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...

  3. 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...

  4. 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.

  5. 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.…

  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-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.

  8. 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.

  9. 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.

  10. Fault-crossing P delays, epicentral biasing, and fault behavior in Central California

    USGS Publications Warehouse

    Marks, S.M.; Bufe, C.G.

    1979-01-01

    The P delays across the San Andreas fault zone in central California have been determined from travel-time differences at station pairs spanning the fault, using off-fault local earthquake or quarry blast sources. Systematic delays as large as 0.4 sec have been observed for paths crossing the fault at depths of 5-10 km. These delays can account for the apparent deviation of epicenters from the mapped fault trace. The largest delays occur along the San Andreas fault between San Juan Bautista and Bear Valley and Between Bitterwater Valley and Parkfield. Spatial variations in fault behavior correlate with the magnitude of the fault-crossing P delay. The delay decreases to the northwest of San Juan Bautista across the "locked" section of the San Andreas fault and also decreases to the southeast approaching Parkfield. Where the delay is large, seismicity is relatively high and the fault is creeping. ?? 1979.

  11. Possible paleo-stress tensor configurations derived from fault-slip data in eastern Vermont and western New Hampshire

    NASA Astrophysics Data System (ADS)

    Hardcastle, Kenneth C.

    1989-04-01

    The configuration of six possible paleostress tensors have been derived from 152 faults measured in eastern Vermont and western New Hampshire. Populations of potentially genetically related faults were separated using two techniques. Tensor configurations for each population were derived using a linear least squares inversion method based in part on the work of Reches [1987] and a grid search inversion method which tests over 100,000 possible tensors for compatibility with all or portions of the data. Faults belonging to the oldest population (set R; n=24) occur primarily in high-grade rocks. This set is composed of semiductile, northeast trending reverse and west-northwest trending left-lateral faults. Fault fabrics of quartz rods and thin mylonite layers suggest that the host rocks were at crustal levels of 8-10 km during faulting. The derived tensor indicates a roughly east-west σ1 and near vertical σ3. Set R faults are offset by normal faults (sets N1 and N2) and are interpreted to be pre-Mesozoic in age, perhaps related to late Paleozoic Alleghanian compression. Normal and normal oblique faults mineralized with chlorite, calcite, and strained quartz (n=73) have been separated into two populations (sets N1, n=49; and N2, n=24) even though these faults are likely of similar age. Host rocks were probably at moderate crustal depths of perhaps 5 km during faulting. Faults of both sets are most likely related to Mesozoic rifting. Tensor configurations indicate that σ1 plunges steeply northwest (N1) and southeast (N2), and σ3 plunges gently, roughly east-west. These faults cut presumably Mesozoic age dikes and are themselves offset by normal oblique faults (set T) and right-lateral faults (set RL). Strongly deviatoric, near vertical σ1 suggests a thermally driven tectonic regime during the development of normal faulting in New England. Set T (n=25) is composed of normal oblique slip faults mineralized similarly as sets N1 and N2. The plunge of σ1 is 50°N and

  12. On the genetic connection between misorientation and weakness: slip-tendency analysis of exhumed fault zones in the Alps

    NASA Astrophysics Data System (ADS)

    Menegon, L.; Bistacchi, A.; Massironi, M.

    2008-12-01

    Crustal-scale fault zones which show a dip-slip component (either normal or reverse) and have been active for relevant times (e.g. some million years) are very often characterised by an asymmetric distribution of fault rocks, with rocks in the footwall or hangingwall (for normal or reverse faults resp.) showing a transition from relatively higher temperature crystal-plastic deformation mechanisms to low temperature brittle-cataclastic mechanisms. This is the result of progressive exhumation during a deformation continuum and may be predicted with the classic Sibson-Scholz fault zone model. This asymmetric distribution of fault rocks has been verified in exhumed fault zones from the metamorphic core of the Alps (Austroalpine and Penninic domains), such as the extensional Simplon and Brenner detachments, and studied in detail in the Sprechenstein-Mules fault zone (part of the eastern segment of the 700-km-long Periadriatic Fault System). Greenschist facies phyllonites, from a wide shear zone which constitutes the ductile precursor to the Sprechenstein-Mules brittle fault, are exposed at the hangingwall and are characterised by a pervasive SCC' composite foliation, marked by alternating phyllosilicate- and quartz-feldspar-rich layers. Centimetre- to micrometre-scale cataclastic shear zones develop along S, C and C' inherited surfaces. Hence, the hanging wall of the Sprechenstein-Mules fault zone is characterised by a strong mechanical anisotropy, which controls the mode of deformation under brittle conditions. However, given its origin in the plastic-metamorphic environment, this anisotropy is strongly misoriented for reactivation under brittle conditions. To investigate to control exerted by pre-existing ductile foliations on brittle faulting, we applied a development of slip tendency analysis that includes the effect of anisotropy. It shows that, given the mechanical anisotropy and under a realistic palaeo-state of stress, continuing activity along a misoriented and

  13. Three-dimensional Geology of the Hayward Fault and its Correlation with Fault Behavior, Northern California

    NASA Astrophysics Data System (ADS)

    Ponce, D. A.; Graymer, R. C.; Jachens, R. C.; Simpson, R. W.; Phelps, G. A.; Wentworth, C. M.

    2004-12-01

    Relationships between fault behavior and geology along the Hayward Fault were investigated using a three-dimensional geologic model of the Hayward fault and vicinity. The three-dimensional model, derived from geologic, geophysical, and seismicity data, allowed the construction of a `geologic map' of east- and west-side surfaces, maps that show the distribution of geologic units on either side of the fault that truncate against the fault surface. These two resulting geologic maps were compared with seismicity and creep along the Hayward Fault using three-dimensional visualization software. The seismic behavior of the Hayward Fault correlates with rock unit contacts along the fault, rather than in rock types across the fault. This suggests that fault activity is, in part, controlled by the physical properties of the rocks that abut the fault and not by properties of the fault zone itself. For example, far fewer earthquakes occur along the northern part of the fault where an intensely sheared Franciscan mélange on the west side abuts the fault face, compared to the region to the south where more coherent rocks of other Franciscan terranes or the Coast Range Ophiolite are present. More locally, clusters of earthquakes correlate spatially with some of the contacts between Franciscan terranes as well as mafic rocks of the Coast Range Ophiolite. Steady creep rates along the fault correlate with the lateral extent of the San Leandro gabbro, and changes in creep rate correlate with changes in geology. Although preliminary, the results of comparing fault behavior with the inferred three-dimensional geology adjacent to the Hayward Fault suggest that any attempt to understand the detailed distribution of earthquakes or creep along the fault should include consideration of the rock types that abut the fault surface. Such consideration would benefit greatly from incorporating into the three-dimensional geologic model the physical properties of the rock types along the fault.

  14. Sequential Polarity-Reversing Circuit

    NASA Technical Reports Server (NTRS)

    Labaw, Clayton C.

    1994-01-01

    Proposed circuit reverses polarity of electric power supplied to bidirectional dc motor, reversible electro-mechanical actuator, or other device operating in direction depending on polarity. Circuit reverses polarity each time power turned on, without need for additional polarity-reversing or direction signals and circuitry to process them.

  15. Fault development and stress evolution of the post-Hercynian Asturian Basin (Asturias and Cantabria, northwestern Spain)

    NASA Astrophysics Data System (ADS)

    Lepvrier, C.; Martínez-García, E.

    1990-12-01

    The Asturian Basin, an emerged part of the North Iberian continental margin, has been investigated in terms of fault development and stress evolution. The Mesozoic history of this domain is mainly linked to the extensional faulting processes which preceded the opening of the Bay of Biscay. Preserved Jurassic faulted blocks and associated half-graben structures, bounded by WNW-ESE to NW-SE faults, are related to a Late Jurassic (Kimmeridgian?) rifting stage. This fault system seems to have played a major role during the Mesozoic structuring of the basin, suggesting an extension oriented approximately NE-SW. The Cenozoic evolution is related to the Iberia-Eurasia convergence and collision, leading to compressional and subsequent extensional structures. The direction of compression, documented in various sites, was NNW-SSE during an initial early-middle Eocene stage, reoriented probably in the Oligocene to NE-SW. This succession of stress regimes was applied to the same three major fault systems, NE-SW, NW-SE and E-W, which were inherited from the Variscan Orogeny, some of them having already been involved in the latest Stephanian — Early Permian rifting episode. During the Tertiary compressional phase, the NW-SE trend, which is believed to have controlled the late Jurassic tectonic development, was rejuvenated into dextral strike-slip faults, whereas the NE-SW system moved in a sinistral sense. The E-W system was reactivated as reverse faults, giving rise to a partial inversion of the basin.

  16. The influence of topographic stresses on faulting, emphasizing the 2008 Wenchuan, China earthquake rupture

    NASA Astrophysics Data System (ADS)

    Styron, R. H.; Hetland, E. A.; Zhang, G.

    2013-12-01

    distribution, considering several published fault models. These models differ primarily in slip magnitude and planar vs. listric fault geometry at depth. Preliminary results indicate that topographic stresses are generally resistive to tectonic deformation, especially above ~10 km depth, where the faults are steep in all models. Down-dip topographic shear stresses on the fault are normal sense where the faults dip steeply, and reach 20 MPa on the fault beneath the Pengguan massif. Reverse-sense shear up to ~15 MPa is present on gently-dipping thrust flats at depth on listric fault models. Strike-slip shear stresses are sinistral on the steep, upper portions of faults but may be dextral on thrust flats. Topographic normal stress on the faults reaches ~80 MPa on thrust ramps and may be higher on flats. Coseismic slip magnitude is negatively correlated with topographic normal and down-dip shear stresses. The spatial patterns of topographic stresses and slip suggest that topographic stresses have significantly suppressed slip in certain areas: slip maxima occur in areas of locally lower topographic stresses, while areas of higher down-dip shear and normal stress show less slip than adjacent regions.

  17. Recurrent late Quaternary surface faulting along the southern Mohawk Valley fault zone, NE California

    SciTech Connect

    Sawyer, T.L.; Hemphill-Haley, M.A. ); Page, W.D. )

    1993-04-01

    The Mohawk Valley fault zone comprises NW- to NNW-striking, normal and strike-slip( ) faults that form the western edge of the Plumas province, a diffuse transitional zone between the Basin and Range and the northern Sierra Nevada. The authors detailed evaluation of the southern part of the fault zone reveals evidence for recurrent late Pleistocene to possibly Holocene, moderate to large surface-faulting events. The southern Mohawk fault zone is a complex, 6-km-wide zone of faults and related features that extends from near the crest of the Sierra Nevada to the middle of southern Sierra Valley. The fault zone has two distinct and generally parallel subzones, 3 km apart, that are delineated by markedly different geomorphic characteristics and apparently different styles of faulting. Paleoseismic activity of the western subzone was evaluated in two trenches: one across a fault antithetic to the main range-bounding fault, and the other across a splay fault delineated by a 3.7-m-high scarp in alluvium. Stratigraphic relations, soil development, and radiocarbon dates indicate that at least four mid- to late-Pleistocene surface-faulting events, having single-event displacements in excess of 1.6 to 2.6 m, occurred along the splay fault prior to 12 ka. The antithetic fault has evidence of three late Pleistocene events that may correspond to event documented on the splay fault, and a Holocene event that is inferred from youthful scarplets and small closed depressions.

  18. 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

  19. 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.

  20. Power dissipation and stress levels on faults in the upper crust

    NASA Astrophysics Data System (ADS)

    Sibson, R. H.

    1980-11-01

    Rock deformation textures from deeply exhumed fault zones in quartzo-feldspathic crust are considered in relation to likely rates of energy dissipation and hence the levels of shear resistance operative during seismic slip in the upper, factional regimes of major crustal dislocations. Available evidence suggests that both low-stress (τ ≤100 bars) and, less commonly, high-stress (τ≥1 kbar) faulting occur, depending on local conditions of which the most important is the ratio of fluid to overburden pressure. The higher stresses are usually associated with immature fault systems, especially reverse faults developed in crystalline host rocks. As a result of initial power dissipation at the onset of slip, feedback mechanisms involving either friction melting or the creation of high transient fluid pressures may drastically diminish kinetic shear resistance over all or part of the rupture surface, the effects becoming more pronounced the greater the initial shear stress. For shallow strike slip earthquakes, values of radiant flux (the wave power radiated per unit area of a fault) range from 0.1 to 10 MW/m2. This suggests that there are considerable variations in seismic efficiency and/or total energy release, even for events of similar magnitude occurring on faults of the same type.

  1. Faults in Quaternary cover as a relfection of basement tectonics: Kolguev island, barents sea

    NASA Astrophysics Data System (ADS)

    Krapivner, R. B.; Skorobogat'ko, A. V.

    2012-09-01

    The paper is concerned with the results of the detailed study of dislocations in the Pliocene-Quaternary loose sediments exposed as cliffs extending for ˜30 km along the rectilinear shore of Kolguev Island. According to seismic data, this lineament is related to the Coastal Fault in the lower part of the sedimentary cover. A system of faults longitudinal, diagonal, and transverse relative to the shoreline is established from observations at the cliffs. Their arrangement in plan view corresponds to the geometry of the right-lateral shear zone, the axis of which almost coincides with the shoreline. This has allowed us to identify the faults as secondary disturbances in the region of dynamic effect of the Coastal Fault in the basement. The kinematics of the secondary faults and their dip azimuth are consistent with echeloned geometry in plan view. The low-angle dip of the reverse-strike-slip faults observed at the outcrops is caused by their near-surface flattening toward the subsided block. The shallow-seated dislocations are related to ductile lateral shear in the vertical plane. The lower layers of the sedimentary cover mimic the horizontal movements in the basement more closely than the upper layers. The data obtained indicate high neotectonic activity of the Barents Sea shelf and specify the geodynamic setting of the region in the Pliocene and Quaternary.

  2. Source fault of 19 August 1966 Varto earthquake and its' mechanism: New field data, Eastern Turkey

    NASA Astrophysics Data System (ADS)

    Gürboğa, Şule

    2015-11-01

    19 August 1966 Varto earthquake (Ms = 6.8; Io = IX) was sourced from Varto Fault Zone (VFZ) that caused 2529 deaths in the Varto region. Just after the occurrence of the event, some researchers have different ideas related to the source fault and mechanism of the earthquake. The Varto Fault Zone is a major NW-SE trending tectonic feature in Eastern Turkey. New geological mapping and description of structures have been used to constrain the geometry, surface deformations and geological history of the fault zone. According to this extensive research, the VFZ consists of left-lateral strike-slip faults with minor amount of reverse component and has been divided into three fault segments Varto, Leylekdağ and Çayçatı regarding as geological and morphological characteristics. Hence, palaeostress configurations of the segments are reliable with the regional ∼N-S compression direction. Lastly, the Varto segment northern branch of VFZ has been defined as the source of 19 August 1966 Varto earthquake.

  3. Active Features of Guguan-Guizhen Fault at the Northeast Margin of Qinghai-Tibet Block since Late Quaternary

    NASA Astrophysics Data System (ADS)

    Shi, Yaqin; Feng, Xijie; Li, Gaoyang; Ma, Ji; Li, Miao; Zhang, Yi

    2015-04-01

    Guguan-Guizhen fault is located at the northeast margin of Qinghai-Tibet Block and northwest margin of Ordos Block; it is the boundary of the two blocks, and one of the multiple faults of northwest Haiyuan-Liupanshan-Baoji fault zone. Guguan-Guizhen fault starts from Putuo Village, Huating County, Gansu Province, and goes through Badu Town, Long County in Shaanxi Province ends in Guozhen Town in Baoji City, Shaanxi Province. The fault has a full length of about 130km with the strike of 310-330°, the dip of SW and the rake of 50-60°, which is a sinistral slip reverse fault in the north part, and a sinistral slip normal fault in the southeast part. Guguan-Guizhen fault has a clear liner structure in satellite images and significant landform elevation difference with a maximum difference of 80m, and is higher in the east lower in the west. The northwest side of Guguan-Guizhen fault is composed of purplish-red Lower Cretaceous sandstones and river terrace; the northeast side is composed of Ordovician Limestone. Shigou, Piliang, Songjiashan, Tianjiagou and Chenjiagou fault profiles are found to the south of Badu Village. After 14C and optically stimulated luminescence dating, the fault does not dislocate the stratum since late Pleistocene (90.5±4.4ka) in Shigou, Piliang and Songjiashan fault profiles, and does not dislocate the cobble layer of Holocene first terrace and recent sliderock (3180±30 BP). But the fault dislocated the stratum of middle Pleistocene in some of the fault profiles. All the evidences above indicate that the fault is active in middle Pleistocene, and being silence since late Pleistocene. It might be active in Holocene to the north of Badu Village due to collapses are found in a certain area. The cause of these collapses is Qinlong M6-7 earthquake in 600 A.D., and might be relevant with Guguan-Guizhen fault after analysis of the scale, feature and age determination of the collapse. If any seismic surface rupture and ancient earthquake traces

  4. Significance of first-order faults in folding mechanically isotropic layers: evidence from the Sudbury Basin, Canada.

    NASA Astrophysics Data System (ADS)

    Clark, Martin; Riller, Ulrich

    2016-04-01

    The Sudbury Basin in Canada is a fold basin demarcated by the Sudbury Igneous Complex (SIC). Folding of the SIC is particularly notable due to its petrographically distinct but mechanically similar layers that are hardly strained when compared to folded strata in other deformed terranes. The Sudbury Basin has three ranges, the North Range, the South Range, and the East Range. The East Range differs from the other ranges by inclosing a remarkably shorter SIC segment with a strong concave curvature. Lacking significant mechanical anisotropy and solid-state strain within the SIC brings to question how the SIC in the East Range acquired its curvature. To address this question, we analyzed the orientation of prominent km-scale faults and their slip vectors. These faults transect the SIC at low angles and mimic its plan view curvature suggesting that the faults were folded along with the SIC. We have developed a G.I.S.-based workflow to address this problem that harnesses high-resolution LiDAR data to generate near surface fault geometries, and combines these geometries with local fault-slip inversions of slickensides to identify slip vectors of prominent curved faults. Analysis of slip vectors along curved faults yields clusters of slip vectors with normal and reverse slip motion in the northern and southern fault segments, respectively. The variation in slip vectors is interpreted to be non-primary and thus shows a temporal relationship between faulting and folding of the SIC. Therefore, prominent curved faults in the East Range must have occurred as a pre-folding brittle response to horizontal shortening. These faults later assumed the role of mechanical anisotropic elements necessary for folding of the SIC layers to occur. This interpretation is corroborated by two sets of principal strain axes inferred from fault-slip inversions. The first set is characterized by its principal axis of shortening oriented NW-SE, comparable in orientation to regional shortening as

  5. Quaternary layer anomalies around the Carlsberg Fault zone mapped with high-resolution shear-wave seismics south of Copenhagen

    NASA Astrophysics Data System (ADS)

    Kammann, Janina; Hübscher, Christian; Nielsen, Lars; Boldreel, Lars Ole

    2015-04-01

    normal block faults and one reverse block fault showing the complexity of the fault zone. The observed faults appear to affect both the Danian as well as the Quaternary successions. We conclude that such investigations are critical for judgment regarding whether or not faults in the study area affect recently deposited strata and if the zone is tectonically active.

  6. 3D Dynamic Rupture Simulation Across a Complex Fault System: the Mw7.0, 2010, Haiti Earthquake

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  7. 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.

  8. Detection of faults and software reliability analysis

    NASA Technical Reports Server (NTRS)

    Knight, J. C.

    1986-01-01

    Multiversion or N-version programming was proposed as a method of providing fault tolerance in software. The approach requires the separate, independent preparation of multiple versions of a piece of software for some application. Specific topics addressed are: failure probabilities in N-version systems, consistent comparison in N-version systems, descriptions of the faults found in the Knight and Leveson experiment, analytic models of comparison testing, characteristics of the input regions that trigger faults, fault tolerance through data diversity, and the relationship between failures caused by automatically seeded faults.

  9. 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.

  10. 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.

  11. Fault-scarp related features and cascade-rupturing model for the Wenchuan earthquake (Mw7.9), eastern Tibetan Plateau, China

    NASA Astrophysics Data System (ADS)

    Yu, G.; Xu, X.; Klinger, Y.; Diao, G.; Chen, G.; Feng, X.; Li, C.; Zhu, A.; Yuan, R.; Guo, T.; Sun, X.; Tan, X.; An, Y.

    2009-12-01

    The post-earthqauke field investigations reveal that the Mw 7.9 Wenchuan earthquake of 12th May 2008 ruptured three reverse faults, two NE-trending imbricated reverse faults and another NW-trending reverse fault, along the middle Longmenshan fold-and-thrust belt at the eastern margin of the Tibetan plateau. The fault-scarp related features can be categorized into eight characterized groups: simple thrust scarp, hanging-wall collapse scarp, simple pressure ridge, dextral pressure ridge, fault-related fold scarp, back-thrust pressure ridge, local normal fault scarp and crocodile-mouth-like scarp. The local normal scarp is first discovered in the reverse-faulting earthquake events as ever reported in the world. The combination of different fault-scarp features, along-strike variation of the co-seismic offsets and fault-trace discontinuity sizes demonstrates that the surface ruptures associated with Wenchuan earthquake are dominated by reverse sense with right-lateral components, but the relative ratio varies from site to site. Also, the surface ruptures can be divided, for the first order, into two segments, the Yingxiu and Beichuan segments, corresponding to Mw 7.8 and Mw 7.57 events, respectively. These two segments further can be divided, for the second order, into four sub-segments in total, which are equivalent to four sub-events of Mw 7.46, Mw 7.69, Mw 6.99 and Mw 7.52, respectively. The rupture segmentation, for different orders, shows a cascade-rupturing pattern and may help explain why the quake time of the Wenchuan earthquake was so long as up to 100 second. Aftershock focal mechanisms are also used to constrain the fault geometry for the sub-segments, indicating that the seismogenic faults are listric at depth and in general, the fault plane becomes steeper northward, which enables the fault to accommodate larger strike-slip motion. This earthquake also confirms that the crustal shortening across the Longmenshan fold-and-thrust belt should be responsible

  12. Bayesian Estimation of 3D Non-planar Fault Geometry and Slip: An application to the 2011 Megathrust (Mw 9.1) Tohoku-Oki Earthquake

    NASA Astrophysics Data System (ADS)

    Dutta, Rishabh; Jónsson, Sigurjón

    2016-04-01

    Earthquake faults are generally considered planar (or of other simple geometry) in earthquake source parameter estimations. However, simplistic fault geometries likely result in biases in estimated slip distributions and increased fault slip uncertainties. In case of large subduction zone earthquakes, these biases and uncertainties propagate into tsunami waveform modeling and other calculations related to postseismic studies, Coulomb failure stresses, etc. In this research, we parameterize 3D non-planar fault geometry for the 2011 Tohoku-Oki earthquake (Mw 9.1) and estimate these geometrical parameters along with fault slip parameters from onland and offshore GPS using Bayesian inference. This non-planar fault is formed using several 3rd degree polynomials in along-strike (X-Y plane) and along-dip (X-Z plane) directions that are tied together using a triangular mesh. The coefficients of these polynomials constitute the fault geometrical parameters. We use the trench and locations of past seismicity as a priori information to constrain these fault geometrical parameters and the Laplacian to characterize the fault slip smoothness. Hyper-parameters associated to these a priori constraints are estimated empirically and the posterior probability distribution of the model (fault geometry and slip) parameters is sampled using an adaptive Metropolis Hastings algorithm. The across-strike uncertainties in the fault geometry (effectively the local fault location) around high-slip patches increases from 6 km at 10km depth to about 35 km at 50km depth, whereas around low-slip patches the uncertainties are larger (from 7 km to 70 km). Uncertainties in reverse slip are found to be higher at high slip patches than at low slip patches. In addition, there appears to be high correlation between adjacent patches of high slip. Our results demonstrate that we can constrain complex non-planar fault geometry together with fault slip from GPS data using past seismicity as a priori

  13. Faulting apparently related to the 1994 Northridge, California, earthquake and possible co-seismic origin of surface cracks in Potrero Canyon, Los Angeles County, California

    USGS Publications Warehouse

    Catchings, R.D.; Goldman, M.R.; Lee, W.H.K.; Rymer, M.J.; Ponti, D.J.

    1998-01-01

    Apparent southward-dipping, reverse-fault zones are imaged to depths of about 1.5 km beneath Potrero Canyon, Los Angeles County, California. Based on their orientation and projection to the surface, we suggest that the imaged fault zones are extensions of the Oak Ridge fault. Geologic mapping by others and correlations with seismicity studies suggest that the Oak Ridge fault is the causative fault of the 17 January 1994 Northridge earthquake (Northridge fault). Our seismically imaged faults may be among several faults that collectively comprise the Northridge thrust fault system. Unusually strong shaking in Potrero Canyon during the Northridge earthquake may have resulted from focusing of seismic energy or co-seismic movement along existing, related shallow-depth faults. The strong shaking produced ground-surface cracks and sand blows distributed along the length of the canyon. Seismic reflection and refraction images show that shallow-depth faults may underlie some of the observed surface cracks. The relationship between observed surface cracks and imaged faults indicates that some of the surface cracks may have developed from nontectonic alluvial movement, but others may be fault related. Immediately beneath the surface cracks, P-wave velocities are unusually low (<400 m/sec), and there are velocity anomalies consistent with a seismic reflection image of shallow faulting to depths of at least 100 m. On the basis of velocity data, we suggest that unconsolidated soils (<800 m/sec) extend to depths of about 15 to 20 m beneath our datum (<25 m below ground surface). The underlying rocks range in velocity from about 1000 to 5000 m/sec in the upper 100 m. This study illustrates the utility of high-resolution seismic imaging in assessing local and regional seismic hazards.

  14. 3D Image Tour of the Hayward Fault in the East Bay, San Francisco Bay Region, California

    NASA Astrophysics Data System (ADS)

    Stoffer, P.

    2007-12-01

    A 3D image tour of the Hayward Fault begins at its northern land-based terminus at Point Pinole from where it continues northward under the waters of San Pablo Bay. From Point Pinole, the Hayward Fault extends southward for about 90 kilometers through the urbanized landscape of the East Bay region, passing through the cities of Richmond, Berkeley, Oakland, San Leandro, Hayward, Fremont, and other communities. At its southern end, the fault forms a series of oblique reverse faults, but at depth it connects with the Calaveras Fault as a through-going structure along the western foothills of the Diablo Range east of the greater San Jose area. This presentation focuses on access to the Hayward Fault in public places where features impacted by active fault creep can be viewed. Features include offset curbs, fractures in sidewalks, parking areas, buildings, and damage to other infrastructure in the active fault zone. Additional images highlight landscape features and historic landmarks along the fault, including those that were impacted by the 1868 Hayward earthquake, and those that were or were engineered both with and without consideration of the location of the fault. Earthquake data and geologic interpretations of the subsurface along the fault zone are also presented. This presentation, and an associated website, is for educational audiences with the intent of promoting public awareness and earthquake preparedness. This work is part of the ongoing outreach and public education efforts by the U.S. Geological Survey in cooperation with the 1868 Hayward Earthquake Alliance in anticipation of the 140th anniversary of the great earthquake. The use of 3D imagery enhances the educational value of the presentation and provides a unique perspective on the subject matter. Red-and-cyan 3D viewing glasses will be available at the presentation.

  15. Study of Magnetic Fabrics across the Central Part of the Chimei Fault, the Coastal Range of Eastern Taiwan

    NASA Astrophysics Data System (ADS)

    Yeh, E. C.; Chu, Y. R.; Chou, Y. M.; Lee, T. Q.; Kuo, S. T.; Cai, Y. M.

    2015-12-01

    Taiwan is an ongoing collisional mountain belt located in the conjunction of two subduction-arc systems with opposite vergences between the Philippine Sea and Eurasian plates. The Coastal Range along the eastern Taiwan is the accreted Luzon arcs and surrounding basins onto the Eurasian crust. The Chimei fault, a typical lithology-contrast fault thrusting the Miocene volcanic Tuluanshan Formation over the Pleistocene sedimentary Paliwan Formation, is the only major reverse fault across the entire Coastal Range. To investigate the deformation pattern and strain history across the Chimei fault, we analyzed oriented samples of mudstone and volcanic rocks across the fault zone, fold zone, damage zone, and wall rocks along the Hsiukuluan River via anisotropy of magnetic susceptibility (AMS). AMS can be represented as a susceptibility ellipsoid with 3 principal directions and values (Kmax, Kint, Kmin) and therefore is well known as a tool of magnetic fabrics to study the deformation. Results of AMS across the central part of the Chimei fault show that the direction of Kmax changed from N-S orientation to sub-vertical and the orientation of Kmin switched from 270/70 to N-S orientation when samples were closed to the fault zone. At the same time, anisotropy was increasing and susceptibility ellipsoid changed from oblate to prolate in the fold zone back to oblate in the fault zone. Based on identification works of magnetic minerals, the major magnetic carrier is magnetite with pseudo-single domain. As a result, it strongly speculated when samples were approaching to the central part of Chimei fault, stress altered from sub-vertical sedimentary loading to horizontally N-S tectonic compression. Due to increasing deformation, oblate ellipsoids with strong anisotropy developed within the fault zone highlighted the strain history of the central part of the Chimei fault.

  16. Experiments in fault tolerant software reliability

    NASA Technical Reports Server (NTRS)

    Mcallister, David F.; Vouk, Mladen A.

    1989-01-01

    Twenty functionally equivalent programs were built and tested in a multiversion software experiment. Following unit testing, all programs were subjected to an extensive system test. In the process sixty-one distinct faults were identified among the versions. Less than 12 percent of the faults exhibited varying degrees of positive correlation. The common-cause (or similar) faults spanned as many as 14 components. However, a majority of these faults were trivial, and easily detected by proper unit and/or system testing. Only two of the seven similar faults were difficult faults, and both were caused by specification ambiguities. One of these faults exhibited variable identical-and-wrong response span, i.e. response span which varied with the testing conditions and input data. Techniques that could have been used to avoid the faults are discussed. For example, it was determined that back-to-back testing of 2-tuples could have been used to eliminate about 90 percent of the faults. In addition, four of the seven similar faults could have been detected by using back-to-back testing of 5-tuples. It is believed that most, if not all, similar faults could have been avoided had the specifications been written using more formal notation, the unit testing phase was subject to more stringent standards and controls, and better tools for measuring the quality and adequacy of the test data (e.g. coverage) were used.

  17. 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.

  18. 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.

  19. 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.

  20. From folding to transpressional faulting: the Cenozoic Fusha structural belt in front of the Western Kunlun Orogen, northwestern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Wang, Cong; Cheng, Xiao-Gan; Chen, Han-Lin; Li, Kang; Fan, Xiao-Gen; Wang, Chun-Yang

    2016-03-01

    Fusha structural belt (FSB) is one of the most important tectonic units in front of the Western Kunlun Orogen, northwestern Tibetan Plateau (NW China), in which the Kekeya oil field was discovered in 1971. However, there is no new oil field discovered since then due to the unclarity of the intense and complex Cenozoic deformation in this area. Based on field investigation, seismic interpretation and Continuous Electromagnetic Profile data, we analyze in detail the Cenozoic deformation history, emphasizing on the spatial and temporal variation of the deformation of the FSB in this paper. The result suggests that the FSB was dominated by two deformation events, (1) early (Miocene-early Pliocene) folding event expressed by anticline, with the western segment E-W orienting, while the eastern segment NWW-SEE orienting and (2) later (since late Pliocene) transpressional faulting event that destroyed and divided the earlier anticline into a number of fault blocks. The transpressional faulting caused dextral strike-slip reverse fault, with the dip angles decreasing eastward from ~90° to <45°. The dextral strike-slip reverse fault developed in the core of the anticline in the western part which caused the anticline into several fault blocks, while in the eastern part, the fault developed in the north limb of the anticline with the core of the anticline reserved. Based on the spatial variation of structural characteristics, we propose that the fault block traps and anticline traps in the eastern segment and fault block traps in western segment are favorable for hydrocarbon accumulation.

  1. From folding to transpressional faulting: the Cenozoic Fusha structural belt in front of the Western Kunlun Orogen, northwestern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Wang, Cong; Cheng, Xiao-Gan; Chen, Han-Lin; Li, Kang; Fan, Xiao-Gen; Wang, Chun-Yang

    2016-07-01

    Fusha structural belt (FSB) is one of the most important tectonic units in front of the Western Kunlun Orogen, northwestern Tibetan Plateau (NW China), in which the Kekeya oil field was discovered in 1971. However, there is no new oil field discovered since then due to the unclarity of the intense and complex Cenozoic deformation in this area. Based on field investigation, seismic interpretation and Continuous Electromagnetic Profile data, we analyze in detail the Cenozoic deformation history, emphasizing on the spatial and temporal variation of the deformation of the FSB in this paper. The result suggests that the FSB was dominated by two deformation events, (1) early (Miocene-early Pliocene) folding event expressed by anticline, with the western segment E-W orienting, while the eastern segment NWW-SEE orienting and (2) later (since late Pliocene) transpressional faulting event that destroyed and divided the earlier anticline into a number of fault blocks. The transpressional faulting caused dextral strike-slip reverse fault, with the dip angles decreasing eastward from ~90° to <45°. The dextral strike-slip reverse fault developed in the core of the anticline in the western part which caused the anticline into several fault blocks, while in the eastern part, the fault developed in the north limb of the anticline with the core of the anticline reserved. Based on the spatial variation of structural characteristics, we propose that the fault block traps and anticline traps in the eastern segment and fault block traps in western segment are favorable for hydrocarbon accumulation.

  2. Seismic constraints and coulomb stress changes of a blind thrust fault system, 1: Coalinga and Kettleman hills, California

    USGS Publications Warehouse

    Lin, Jian; Stein, Ross S.

    2006-01-01

    This report reviews the seismicity and surface ruptures associated with the 1982-1985 earthquake sequence in the Coalinga region in California, and the role of Coulomb stress in triggering the mainshock sequence and aftershocks. The 1982-1985 New Idria, Coalinga, and Kettleman Hills earthquakes struck on a series of west-dipping, en echelon blind thrust faults. Each earthquake was accompanied by uplift of a Quaternary anticline atop the fault, and each was accompanied by a vigorous aftershock sequence. Aftershocks were widely dispersed, and are seen above and below the thrust fault, as well as along the up-dip and down-dip projection of the main thrust fault. For the Coalinga and Kettleman Hills earthquakes, high-angle reverse faults in the core of the anticlines are evident in seismic reflection profiles, and many of these faults are associated with small aftershocks. The shallowest aftershocks extended to within 3-4 km of the ground surface. There is no compelling evidence for aftershocks associated with flexural slip faulting. No secondary surface rupture was found on any of the anticlines. In contrast, the 1983 Nu?ez rupture struck on a high-angle reverse fault 10 km west of the Coalinga epicenter, and over a 40-80-day period, up to 1 m of oblique surface slip occurred. The slip on this Holocene fault likely extended from the ground surface to a depth of 8-10 km. We argue that both the Nu?ez and Kettleman earthquakes were triggered by stresses imparted by the Coalinga mainshock, which was the largest of the four events in the sequence.

  3. 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.

  4. 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.

  5. Parallel fault-tolerant robot control

    NASA Technical Reports Server (NTRS)

    Hamilton, D. L.; Bennett, J. K.; Walker, I. D.

    1992-01-01

    A shared memory multiprocessor architecture is used to develop a parallel fault-tolerant robot controller. Several versions of the robot controller are developed and compared. A robot simulation is also developed for control observation. Comparison of a serial version of the controller and a parallel version without fault tolerance showed the speedup possible with the coarse-grained parallelism currently employed. The performance degradation due to the addition of processor fault tolerance was demonstrated by comparison of these controllers with their fault-tolerant versions. Comparison of the more fault-tolerant controller with the lower-level fault-tolerant controller showed how varying the amount of redundant data affects performance. The results demonstrate the trade-off between speed performance and processor fault tolerance.

  6. Alp Transit: Crossing Faults 44 and 49

    NASA Astrophysics Data System (ADS)

    El Tani, M.; Bremen, R.

    2014-05-01

    This paper describes the crossing of faults 44 and 49 when constructing the 57 km Gotthard base tunnel of the Alp Transit project. Fault 44 is a permeable fault that triggered significant surface deformations 1,400 m above the tunnel when it was reached by the advancing excavation. The fault runs parallel to the downstream face of the Nalps arch dam. Significant deformations were measured at the dam crown. Fault 49 is sub-vertical and permeable, and runs parallel at the upstream face of the dam. It was necessary to assess the risk when crossing fault 49, as a limit was put on the acceptable dam deformation for structural safety. The simulation model, forecasts and action decided when crossing over the faults are presented, with a brief description of the tunnel, the dam, and the monitoring system.

  7. 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.

  8. The geometry of the active strike-slip El Tigre Fault, Precordillera of San Juan, Central-Western Argentina: integrating resistivity surveys with structural and geomorphological data

    NASA Astrophysics Data System (ADS)

    Fazzito, Sabrina Y.; Cortés, José M.; Rapalini, Augusto E.; Terrizzano, Carla M.

    2013-07-01

    The geometry and related geomorphological features of the right-lateral strike-slip El Tigre Fault, one of the main morphostructural discontinuities in the Central-Western Precordillera of Argentina, were investigated. Achievements of this survey include: recognition of structural and geometrical discontinuities along the fault trace, identification and classification of landforms associated with local transpressional and transtensional sectors, observation of significant changes in the fault strike and detection of right and left bends of different wavelength. In the Central Segment of the El Tigre Fault, 2D electrical resistivity tomography surveys were carried out across the fault zone. The resistivity imaging permitted to infer the orientation of the main fault surface, the presence of blind fault branches along the fault zone, tectonic tilting of the Quaternary sedimentary cover, subsurface structure of pressure ridges and depth to the water table. Based on this information, it is possible to characterize the El Tigre Fault also as an important hydro-geological barrier. Our survey shows that the main fault surface changes along different segments from a high-angle to a subvertical setting whilst the vertical-slip component is either reverse or normal, depending on the local transpressive or transtensive regime induced by major bends along the trace. These local variations are expressed as sections of a few kilometres in length with relatively homogeneous behaviour and frequently separated by oblique or transversal structures.

  9. Evidence of Crustal Faulting and Deformation in the Muckleshoot Basin, Washington

    NASA Astrophysics Data System (ADS)

    Cox, J.; Wolf, L. W.

    2015-12-01

    The Muckleshoot basin of western Washington, sandwiched between the Seattle Uplift on the west and the Cascade Range on the east, is deforming under north-south shortening and clockwise rotation of the north Cascadia forearc. Accommodating the regional strain are crustal faults in the Puget Lowland that cluster around three azimuths: east-west, northwest-southeast, and north-northwest-south-southeast. Evidence for all three groups appears on the periphery of the Muckleshoot basin. In this study, we add gravity measurements to an existing database to better define the geometry of the Muckleshoot basin and its relation to previously mapped faults appearing on the basin margins. A northwest-trending gravity high bisects the basin into two sub-basins, a larger one to the south and a smaller one to the north. We suggest that the gravity high is associated with a deep basement structure and its orientation is consistent with northward-directed crustal shortening. Regional-residual separation methods and derivative maps show pronounced magnetic lineations that extend faults expressed along the basin margins to east-west trending faults that cross the Puget Sound. Three intersecting cross-sectional models produced for this study are consistent with the following hypotheses: (1) the northwest-trending White River and Green River faults mapped on the eastern basin margin appear as south-verging, steeply dipping reverse faults in the central basin; (2) the north-northwest trending Franklin fault, mapped previously as a strike-slip fault, projects into the basin and shows little vertical offset in the single profile it crosses, and (3) the northwest trajectory of both the White River and Green River faults appears to curve southward as the faults traverse the Muckleshoot basin, following east-west oriented gravity and magnetic anomalies that cross the Puget Sound. Results from the study suggest that the faults and folds in Muckleshoot basin are actively interacting with other

  10. Fault imprint in clay units: magnetic fabric, structural and mineralogical signature

    NASA Astrophysics Data System (ADS)

    Moreno, Eva; Homberg, Catherine; Schnyder, Johann; Person, Alain; du Peloux1, Arthur; Dick, Pierre

    2014-05-01

    Fault-induced deformations in clay units can be difficult to decipher because strain markers are not always visible at outcrop scale or using geophysical methods. Previous studies have indicated that the anisotropy of magnetic susceptibility (ASM) provides a powerful and rapid technique to investigate tectonic deformation in clay units even when they appear quite homogenous and undeformed at the outcrop scale (Lee et al. 1990, Mattei et al. 1997). We report here a study based on ASM, structural analysis and magnetic and clay mineralogy from two boreholes (TF1 and ASM1)drilled horizontally in the Experimental Station of Tournemire of the Institute for Radiological Protection and Nuclear Safety (IRSN) in Aveyron (France). The boreholes intersect a N-S trending strike-slip fault from west to east. The ASM study indicates the evolution of the magnetic fabric from the undeformed host rock to the fault core. Also, all the fractures cutting the studied interval of the core have been measured as well as the slip vectors which are generally well preserved. In the two boreholes, the undeformed sediments outside the fault zone are characterized by an oblate fabric, a sub-vertical minimum susceptibility axis (k3) perpendicular to the bedding plane and without magnetic lineation. Within the fault zone, a tilt in the bedding plane has been observed in two boreholes TF1 and ASM1. In addition, in the TF1 core, the fault area presents a tectonic fabric characterized by a triaxial AMS ellipsoid. Moreover, the magnetic lineation increases and k3 switches from a vertical to a sub-horizontal plane. This kind of fabric has not been observed in borehole ASM1. The structural analysis of the individual fractures making the fault zone indicates a complex tectonic history with different imprint in the two fault segments cut by the two boreholes. The large majority of fractures correspond to dextral strike-slip faults but normal and reverse movements were observed and are more or less

  11. Kinematics, mechanics, and potential earthquake hazards for faults in Pottawatomie County, Kansas, USA

    USGS Publications Warehouse

    Ohlmacher, G.C.; Berendsen, P.

    2005-01-01

    Many stable continental regions have subregions with poorly defined earthquake hazards. Analysis of minor structures (folds and faults) in these subregions can improve our understanding of the tectonics and earthquake hazards. Detailed structural mapping in Pottawatomie County has revealed a suite consisting of two uplifted blocks aligned along a northeast trend and surrounded by faults. The first uplift is located southwest of the second. The northwest and southeast sides of these uplifts are bounded by northeast-trending right-lateral faults. To the east, both uplifts are bounded by north-trending reverse faults, and the first uplift is bounded by a north-trending high-angle fault to the west. The structural suite occurs above a basement fault that is part of a series of north-northeast-trending faults that delineate the Humboldt Fault Zone of eastern Kansas, an integral part of the Midcontinent Rift System. The favored kinematic model is a contractional stepover (push-up) between echelon strike-slip faults. Mechanical modeling using the boundary element method supports the interpretation of the uplifts as contractional stepovers and indicates that an approximately east-northeast maximum compressive stress trajectory is responsible for the formation of the structural suite. This stress trajectory suggests potential activity during the Laramide Orogeny, which agrees with the age of kimberlite emplacement in adjacent Riley County. The current stress field in Kansas has a N85??W maximum compressive stress trajectory that could potentially produce earthquakes along the basement faults. Several epicenters of seismic events (faults, is similar to that mapped in the New Madrid Seismic Zone, and both areas currently feature roughly east-west maximum

  12. Time reversal communication system

    DOEpatents

    Candy, James V.; Meyer, Alan W.

    2008-12-02

    A system of transmitting a signal through a channel medium comprises digitizing the signal, time-reversing the digitized signal, and transmitting the signal through the channel medium. The channel medium may be air, earth, water, tissue, metal, and/or non-metal.

  13. Justice and Reverse Discrimination

    ERIC Educational Resources Information Center

    Strike, Kenneth A.

    1976-01-01

    Although this article does not necessarily recommend policies of reverse discrimination, arguments indicating that such policies are not contradictory to accepted concepts of justice are presented. The necessity of dispersing any consequent injury to society as a whole rather than to individuals is stressed. (RW)

  14. Reversing Discrimination: A Perspective

    ERIC Educational Resources Information Center

    Pati, Gopal; Reilly, Charles W.

    1977-01-01

    Examines the debate over affirmative action and reverse discrimination, and discusses how and why the present dilemma has developed. Suggests that organizations can best address the problem through an honest, in-depth analysis of their organizational structure and management practices. (JG)

  15. Andexanet: Effectively Reversing Anticoagulation.

    PubMed

    Lippi, Giuseppe; Sanchis-Gomar, Fabian; Favaloro, Emmanuel J

    2016-06-01

    Despite direct oral anticoagulants becoming a mainstay of anticoagulant therapy, the effective, timely, and safe reversal of their anticoagulant effect remains challenging. Emerging evidence attests that andexanet, a recombinant and inactive variant of native factor X (FXa), competitively inhibits and counteracts the anticoagulant effect of many inhibitors of native activated FXa. PMID:27048885

  16. Reversible Ising dynamics

    SciTech Connect

    Creutz, M.

    1985-01-01

    The author discusses a reversible deterministic dynamics for Ising spins. The algorithm is a variation of microcanonical Monte Carlo techniques and is easily implemented with simple bit manipulation. This provides fast programs to study non-equilibrium phenomena such as heat flow.

  17. Reverse Coherent Information

    NASA Astrophysics Data System (ADS)

    García-Patrón, Raúl; Pirandola, Stefano; Lloyd, Seth; Shapiro, Jeffrey H.

    2009-05-01

    In this Letter we define a family of entanglement distribution protocols assisted by feedback classical communication that gives an operational interpretation to reverse coherent information, i.e., the symmetric counterpart of the well-known coherent information. This leads to the definition of a new entanglement distribution capacity that exceeds the unassisted capacity for some interesting channels.

  18. Reverse Coherent Information

    NASA Astrophysics Data System (ADS)

    García-Patrón, Raúl; Pirandola, Stefano; Lloyd, Seth; Shapiro, Jeffrey H.

    2009-04-01

    We define a family of entanglement distribution protocols assisted by classical feedback communication that gives an operational interpretation to reverse coherent information, i.e., the symmetric counterpart of the well-known coherent information. This protocol family leads to the definition of a new entanglement distribution capacity that exceeds the unassisted entanglement distribution capacity for some interesting channels.

  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

  20. Geodetically derived fault slip distribution model for the May, 11th 2011 Lorca earthquake (SE, Spain)

    NASA Astrophysics Data System (ADS)

    Gonzalez, P. J.; Tiampo, K. F.; Palano, M.; Cannavò, F.; Fernandez, J.

    2011-12-01

    The Alhama de Murcia Fault (AMF) is a compound multisegmented right-lateral to reverse fault system. The AMF is one the longest faults in the Eastern Betics Shear zone (Southeastern Spain). In the last decades its seismogenic potential has been evaluated and earthquake maximum magnitudes were forecast based on paleoseismic and dating data. On May 11th, 2011 a moderate (Mw 5.1) earthquake shook the region, causing 9 casualties and severe damages in Lorca city (Murcia region). The reported location of the aftershocks sequence did not follow any particular trend; furthermore in-situ geology surveys did not identify any fault slip related ground deformation. To contribute to a better seismic hazard assessment, we need to locate and, if possible, characterize the fault-slip distribution that generated the earthquake. In this work, we detected small but significant ground deformation in the epicentral area by using geodetic (GPS and satellite radar interferometry) data. Geodetic data was processed by using a stack of differential radar interferometry (corrected for a known subsidence contribution and estimating their error budget), daily GPS estimated coordinates and high-rate 1-Hz GPS data. We jointly inverted the detected static coseismic displacements (a GPS station and two ENVISAT interferograms from different tracks) for the fault plane geometry parameters by using a rectangular dislocation model embedded in a homogeneous elastic half-space. The best-fitting fault plane follows closely the geologically derived AMF geometry (NE-SW strike trend and dipping ~60-70o to NW). Later, the obtained model geometry was extended and divided into patches to allow for a detailed analysis of the fault slip distribution pattern. Slip distribution indicates that slip occurred in a single patch with reverse and right-lateral motion (with peak fault slip magnitude of ~9 cm). However, the modelling results also indicate that the fault slip was shallower along the centre and southwest

  1. 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

  2. Distributed transpressive continental deformation: The Varto Fault Zone, eastern Turkey

    NASA Astrophysics Data System (ADS)

    Sançar, Taylan; Zabcı, Cengiz; Akyüz, H. Serdar; Sunal, Gürsel; Villa, Igor M.

    2015-10-01

    The convergence between the Eurasian and Arabian plates has created a complicated structural setting in the Eastern Turkish high plateau (ETHP), particularly around the Karlıova Triple Junction (KTJ) where the Eurasian, Arabian, and Anatolian plates intersect. This region of interest includes the junction of the North Anatolian Shear Zone (NASZ) and the East Anatolian Shear Zone (EASZ), which forms the northern border of the westwardly extruding Anatolian Scholle and the western boundary of the ETHP, respectively. In this study, we focused on a poorly studied component of the KTJ, the Varto Fault Zone (VFZ), and the adjacent secondary structures, which have complex structural settings. Through integrated analyses of remote sensing and field observations, we identified a widely distributed transpressional zone where the Varto segment of the VFZ forms the most northern boundary. The other segments, namely, the Leylekdağ and Çayçatı segments, are oblique-reverse faults that are significantly defined by uplifted topography along their strikes. The measured 515 and 265 m of cumulative uplifts for Mt. Leylek and Mt. Dodan, respectively, yield a minimum uplift rate of 0.35 mm/a for the last 2.2 Ma. The multi-oriented secondary structures were mostly correlated with "the distributed strike-slip" and "the distributed transpressional" in analogue experiments. The misfits in strike of some of secondary faults between our observations and the experimental results were justified by about 20° to 25° clockwise restoration of all relevant structures that were palaeomagnetically measured to have happened since ~ 2.8 Ma ago. Our detected fault patterns and their true nature are well aligned as being part of a transpressional tectonic setting that supports previously suggested stationary triple junction models.

  3. Neotectonic fault structures in the Lake Thun area (Switzerland)

    NASA Astrophysics Data System (ADS)

    Fabbri, Stefano C.; Herwegh, Marco; Schlunegger, Fritz; Hübscher, Christian; Weiss, Benedikt J.; Schmelzbach, Cédric; Horstmeyer, Heinrich; Merz, Kaspar; Anselmetti, Flavio S.

    2016-04-01

    clast as well as significantly offset horizons. The GPR data reveal the occurrence of several morphologic depressions from gypsum cones and clearly dipping reflections. The reflection seismic data set shows prominent reflections, characteristic seismic facies and a few sets of normal and reverse faults in the north western part of the lake basin within the glacio-lacustrine deposits that may point to a transpressional strike-slip regime. A first neotectonic analysis links these prominent lake floor features with geomorphologic patterns from the surrounding landscape, pointing to a potential candidate for a fault that is active in the Quaternary period.

  4. Fault trees and imperfect coverage

    NASA Technical Reports Server (NTRS)

    Dugan, Joanne B.

    1989-01-01

    A new algorithm is presented for solving the fault tree. The algorithm includes the dynamic behavior of the fault/error handling model but obviates the need for the Markov chain solution. As the state space is expanded in a breadth-first search (the same is done in the conversion to a Markov chain), the state's contribution to each future state is calculated exactly. A dynamic state truncation technique is also presented; it produces bounds on the unreliability of the system by considering only part of the state space. Since the model is solved as the state space is generated, the process can be stopped as soon as the desired accuracy is reached.

  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 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

  6. Heat flow, strong near-fault seismic waves, and near-fault tectonics on the central San Andreas Fault

    NASA Astrophysics Data System (ADS)

    Sleep, Norman H.

    2016-05-01

    The main San Andreas Fault strikes subparallel to compressional folds and thrust faults. Its fault-normal traction is on average a factor of γ=1+2μthr>(√(1+μthr2)+μthr>), where μthr is the coefficient of friction for thrust faults, times the effective lithostatic pressure. A useful upper limit for μthr of 0.6 (where γ is 3.12) is obtained from the lack of heat flow anomalies by considering off-fault convergence at a rate of 1 mm/yr for 10 km across strike. If the fault-normal traction is in fact this high, the well-known heat flow constraint of average stresses of 10-20 MPa during strike slip on the main fault becomes more severe. Only a few percent of the total slip during earthquakes can occur at the peak stress before dynamic mechanisms weaken the fault. The spatial dimension of the high-stress rupture-tip zone is ˜10 m for γ = 3.12 and, for comparison, ˜100 m for γ = 1. High dynamic stresses during shaking occur within these distances of the fault plane. In terms of scalars, fine-scale tectonic stresses cannot exceed the difference between failure stress and dynamic stress. Plate-scale slip causes stresses to build up near geometrical irregularities of the fault plane. Strong dynamic stresses near the rupture tip facilitate anelastic deformation with the net effects of relaxing the local deviatoric tectonic stress and accommodating deformation around the irregularities. There also is a mild tendency for near-fault material to extrude upward. Slip on minor thrust faults causes the normal traction on the main fault to be spatially variable.

  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

  9. 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.

  10. Focal Mechanisms of Three Finnish Earthquakes and Their Connection To Surface Faults

    NASA Astrophysics Data System (ADS)

    Uski, M.; Hyvönen, T.; Korja, A.; Airo, M.-L.

    Focal mechanisms of three recent earthquakes in Finland were determined using P wave polarities as well as SV/P and SH/P phase amplitude ratios. The events occurred on May 11th, 2000 in Toivakka, central Finland (ML=2.4), on September 15th, 2000 in Kuusamo, northeastern Finland (ML=3.5), and on May 2nd, 2001 in Kolari, western Lapland (ML=2.9). In order to obtain reliable estimates of the source parameters, local crust and upper mantle velocity models were derived for the epicenter areas. The events were relocated using P- and S-phase arrival times from the nearest stations and the new velocity models. Synthetic waveforms calculated with the reflectivity method were used to further constrain and verify the source and structural parameters. The well-constrained fault plane solution of the Toivakka earthquake indicates reverse faulting trending 358/42 or 196/50. By comparing the focal planes with magnetic and topographic data of the epicenter area, we suggest the eastward dipping plane to be the actual fault plane. Both the location procedure and synthetic waveform modelling place the focus at the depth of 6 km. The hypocenter parameters of the Kuusamo earthquake are not as well constrained as in the other events, due to lack of seismic stations at distances less than 175 km. The best fitting solution indicates normal-faulting mechanism striking 133/47 or 284/47. Both fault directions are found as pairs of topographic and weak, discontinuous mag- netic lineaments. The focus is located between 12 km and 14 km. The best fitting fault plane solution of the Kolari earthquake suggests pure thrust- faulting mechanism at a shallow depth, 4 km. The strike and dip (030/30) correlates well with the surface observations of postglacial faults in the area.

  11. Crustal structure and fault geometry of the 2010 Haiti earthquake from temporary seismometer deployments

    USGS Publications Warehouse

    Douilly, Roby; Haase, Jennifer S.; Ellsworth, William L.; Bouin, Marie‐Paule; Calais, Eric; Symithe, Steeve J.; Armbruster, John G.; Mercier de Lépinay, Bernard; Deschamps, Anne; Mildor, Saint‐Louis; Meremonte, Mark E.; Hough, Susan E.

    2013-01-01

    Haiti has been the locus of a number of large and damaging historical earthquakes. The recent 12 January 2010 Mw 7.0 earthquake affected cities that were largely unprepared, which resulted in tremendous losses. It was initially assumed that the earthquake ruptured the Enriquillo Plantain Garden fault (EPGF), a major active structure in southern Haiti, known from geodetic measurements and its geomorphic expression to be capable of producing M 7 or larger earthquakes. Global Positioning Systems (GPS) and Interferometric Synthetic Aperture Radar (InSAR) data, however, showed that the event ruptured a previously unmapped fault, the Léogâne fault, a north‐dipping oblique transpressional fault located immediately north of the EPGF. Following the earthquake, several groups installed temporary seismic stations to record aftershocks, including ocean‐bottom seismometers on either side of the EPGF. We use data from the complete set of stations deployed after the event, on land and offshore, to relocate all aftershocks from 10 February to 24 June 2010, determine a 1D regional crustal velocity model, and calculate focal mechanisms. The aftershock locations from the combined dataset clearly delineate the Léogâne fault, with a geometry close to that inferred from geodetic data. Its strike and dip closely agree with the global centroid moment tensor solution of the mainshock but with a steeper dip than inferred from previous finite fault inversions. The aftershocks also delineate a structure with shallower southward dip offshore and to the west of the rupture zone, which could indicate triggered seismicity on the offshore Trois Baies reverse fault. We use first‐motion focal mechanisms to clarify the relationship of the fault geometry to the triggered aftershocks.

  12. 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.

  13. Watching Faults Grow in Sand

    NASA Astrophysics Data System (ADS)

    Cooke, M. L.

    2015-12-01

    Accretionary sandbox experiments provide a rich environment for investigating the processes of fault development. These experiments engage students because 1) they enable direct observation of fault growth, which is impossible in the crust (type 1 physical model), 2) they are not only representational but can also be manipulated (type 2 physical model), 3) they can be used to test hypotheses (type 3 physical model) and 4) they resemble experiments performed by structural geology researchers around the world. The structural geology courses at UMass Amherst utilize a series of accretionary sandboxes experiments where students first watch a video of an experiment and then perform a group experiment. The experiments motivate discussions of what conditions they would change and what outcomes they would expect from these changes; hypothesis development. These discussions inevitably lead to calculations of the scaling relationships between model and crustal fault growth and provide insight into the crustal processes represented within the dry sand. Sketching of the experiments has been shown to be a very effective assessment method as the students reveal which features they are analyzing. Another approach used at UMass is to set up a forensic experiment. The experiment is set up with spatially varying basal friction before the meeting and students must figure out what the basal conditions are through the experiment. This experiment leads to discussions of equilibrium and force balance within the accretionary wedge. Displacement fields can be captured throughout the experiment using inexpensive digital image correlation techniques to foster quantitative analysis of the experiments.

  14. 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.

  15. Slip rate and slip magnitudes of past earthquakes along the Bogd left-lateral strike-slip fault (Mongolia)

    USGS Publications Warehouse

    Prentice, Carol S.; Rizza, M.; Ritz, J.F.; Baucher, R.; Vassallo, R.; Mahan, S.

    2011-01-01

    We carried out morphotectonic studies along the left-lateral strike-slip Bogd Fault, the principal structure involved in the Gobi-Altay earthquake of 1957 December 4 (published magnitudes range from 7.8 to 8.3). The Bogd Fault is 260 km long and can be subdivided into five main geometric segments, based on variation in strike direction. West to East these segments are, respectively: the West Ih Bogd (WIB), The North Ih Bogd (NIB), the West Ih Bogd (WIB), the West Baga Bogd (WBB) and the East Baga Bogd (EBB) segments. Morphological analysis of offset streams, ridges and alluvial fans—particularly well preserved in the arid environment of the Gobi region—allows evaluation of late Quaternary slip rates along the different faults segments. In this paper, we measure slip rates over the past 200 ka at four sites distributed across the three western segments of the Bogd Fault. Our results show that the left-lateral slip rate is∼1 mm yr–1 along the WIB and EIB segments and∼0.5 mm yr–1 along the NIB segment. These variations are consistent with the restraining bend geometry of the Bogd Fault. Our study also provides additional estimates of the horizontal offset associated with the 1957 earthquake along the western part of the Bogd rupture, complementing previously published studies. We show that the mean horizontal offset associated with the 1957 earthquake decreases progressively from 5.2 m in the west to 2.0 m in the east, reflecting the progressive change of kinematic style from pure left-lateral strike-slip faulting to left-lateral-reverse faulting. Along the three western segments, we measure cumulative displacements that are multiples of the 1957 coseismic offset, which may be consistent with a characteristic slip. Moreover, using these data, we re-estimate the moment magnitude of the Gobi-Altay earthquake at Mw 7.78–7.95. Combining our slip rate estimates and the slip distribution per event we also determined a mean recurrence interval of∼2500

  16. Slip rate and slip magnitudes of past earthquakes along the Bogd left-lateral strike-slip fault (Mongolia)

    USGS Publications Warehouse

    Rizza, M.; Ritz, J.-F.; Braucher, R.; Vassallo, R.; Prentice, C.; Mahan, S.; McGill, S.; Chauvet, A.; Marco, S.; Todbileg, M.; Demberel, S.; Bourles, D.

    2011-01-01

    We carried out morphotectonic studies along the left-lateral strike-slip Bogd Fault, the principal structure involved in the Gobi-Altay earthquake of 1957 December 4 (published magnitudes range from 7.8 to 8.3). The Bogd Fault is 260 km long and can be subdivided into five main geometric segments, based on variation in strike direction. West to East these segments are, respectively: the West Ih Bogd (WIB), The North Ih Bogd (NIB), the West Ih Bogd (WIB), the West Baga Bogd (WBB) and the East Baga Bogd (EBB) segments. Morphological analysis of offset streams, ridges and alluvial fans-particularly well preserved in the arid environment of the Gobi region-allows evaluation of late Quaternary slip rates along the different faults segments. In this paper, we measure slip rates over the past 200 ka at four sites distributed across the three western segments of the Bogd Fault. Our results show that the left-lateral slip rate is ~1 mm yr-1 along the WIB and EIB segments and ~0.5 mm yr-1 along the NIB segment. These variations are consistent with the restraining bend geometry of the Bogd Fault. Our study also provides additional estimates of the horizontal offset associated with the 1957 earthquake along the western part of the Bogd rupture, complementing previously published studies. We show that the mean horizontal offset associated with the 1957 earthquake decreases progressively from 5.2 m in the west to 2.0 m in the east, reflecting the progressive change of kinematic style from pure left-lateral strike-slip faulting to left-lateral-reverse faulting. Along the three western segments, we measure cumulative displacements that are multiples of the 1957 coseismic offset, which may be consistent with a characteristic slip. Moreover, using these data, we re-estimate the moment magnitude of the Gobi-Altay earthquake at Mw 7.78-7.95. Combining our slip rate estimates and the slip distribution per event we also determined a mean recurrence interval of ~2500-5200 yr for past

  17. Coseismic Slip Distribution of the 2010 M7.0 Haiti Earthquake and Resulting Stress Changes on Regional Faults

    NASA Astrophysics Data System (ADS)

    Symithe, S. J.

    2012-12-01

    The Mw 7.0 January 12, 2010, Haiti earthquake ruptured the previously unmapped Léogâne Fault, a secondary transpressional fault located close to the Enriquillo Plantain Garden Fault (EPGF), the major fault system assumed to be the primary source of seismic hazard for southern Haiti. In the absence of a precise aftershock catalog, previous estimations of coseismic slip had to infer the rupture geometry from geodetic and/or seismological data. Here we use a catalog of precisely relocated aftershocks covering the 6 months following the event to constrain the rupture geometry, estimate a slip distribution from an inversion of GPS, InSAR and coastal uplift data, and calculate the resulting changes of Coulomb failure stress on neighboring faults. The relocated aftershocks confirm a north dipping structure consistent with the Léogâne fault, as inferred from previous slip inversions. Our updated source model involves two subfaults, each corresponding to a major slip patch. The eastern one combines strike-slip and dip-slip, while the western one is mostly strike-slip. Overall, the event released 68 % of left-lateral strike-slip and 32 % of dip-slip reverse seismic moment, consistent with secular strain accumulation in southern Haiti from regional GPS studies. Coulomb failure stress changes caused by the coseismic rupture show that the cluster of reverse faulting earthquakes, one as large as M 5.9, that were observed to the west of the coseismic rupture coincident with the offshore Trois Baies fault were likely triggered by the main shock. We find increased stresses on the Enriquillo fault to the west of the January 12, 2010 rupture (Miragoâne area, ~3 bars) and to the east near Port-au-Prince (0.3 to ~1 bar). Other regional faults do not show significant increase of static stresses at seismogenic depth. Increased coseismic stress changes on the Trois Baies fault and portions of the Enriquillo fault to the west and east of the Léogâne rupture are a concern as this

  18. From fissure to fault: A model of fault growth in the Krafla Fissure System, NE Iceland

    NASA Astrophysics Data System (ADS)

    Bramham, Emma; Paton, Douglas; Wright, Tim

    2015-04-01

    Current models of fault growth examine the relationship of fault length (L) to vertical displacement (D) where the faults exhibit the classic fault shape of gradually increasing vertical displacement from zero at the fault tips to a maximum displacement (Dmax) at the middle of the fault. These models cannot adequately explain displacement-length observations at the Krafla fissure swarm, in Iceland's northern volcanic zone, where we observe that many of the faults with significant vertical displacements still retain fissure-like features, with no vertical displacement, along portions of their lengths. We have created a high resolution digital elevation model (DEM) of the Krafla region using airborne LiDAR and measured the displacement/length profiles of 775 faults, with lengths ranging from 10s to 1000s of metres. We have categorised the faults based on the proportion of the profile that was still fissure-like. Fully-developed faults (no fissure-like regions) were further grouped into those with profiles that had a flat-top geometry (i.e. significant proportion of fault length with constant throw), those with a bell-shaped throw profile and those that show regions of fault linkage. We suggest that a fault can most easily accommodate stress by displacing regions that are still fissure-like, and that a fault would be more likely to accommodate stress by linkage once it has reached the maximum displacement for its fault length. Our results demonstrate that there is a pattern of growth from fissure to fault in the Dmax/L ratio of the categorised faults and propose a model for this growth. These data better constrain our understanding of how fissures develop into faults but also provide insights into the discrepancy in D/L profiles from a typical bell-shaped distribution.

  19. 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

  20. 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

  1. 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

  2. 49 CFR 230.89 - Reverse gear.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Reversing Gear § 230.89 Reverse gear. (a) General provisions. Reverse gear, reverse levers, and quadrants shall be maintained in a safe and suitable condition for service. Reverse lever latch shall be...

  3. 49 CFR 230.89 - Reverse gear.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Reversing Gear § 230.89 Reverse gear. (a) General provisions. Reverse gear, reverse levers, and quadrants shall be maintained in a safe and suitable condition for service. Reverse lever latch shall be...

  4. 49 CFR 230.89 - Reverse gear.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Reversing Gear § 230.89 Reverse gear. (a) General provisions. Reverse gear, reverse levers, and quadrants shall be maintained in a safe and suitable condition for service. Reverse lever latch shall be...

  5. 49 CFR 230.89 - Reverse gear.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Reversing Gear § 230.89 Reverse gear. (a) General provisions. Reverse gear, reverse levers, and quadrants shall be maintained in a safe and suitable condition for service. Reverse lever latch shall be...

  6. Application of high resolution DEM data to detect rock damage from geomorphic signals along the central San Jacinto Fault

    NASA Astrophysics Data System (ADS)

    Wechsler, Neta; Rockwell, Thomas K.; Ben-Zion, Yehuda

    2009-12-01

    We analyze geomorphic properties extracted from LiDAR and SRTM (Shuttle Radar Topography Mission) data to test whether the damage zone along the central San Jacinto Fault (SJF) zone can be resolved with remotely-sensed data in a quantitative fashion. The SJF is one of the most active faults in southern California, with well expressed geomorphology and a fast slip rate, as seen in the geology and by GPS. We use ArcMap and the TauDEM toolbox to compare several morphometric parameters, including drainage density (Dd), on both sides of the fault, using a 1 km and a 5 km buffer for the LiDAR and SRTM data, respectively. We also analyze the spatial patterns of Dd near the fault, using two different definitions of spatial Dd. The high resolution of the LiDAR data allows us to focus on a single fault, eliminating the effects of parallel nearby faults. From the LiDAR data we find that the highest Dd values occur in areas between two fault strands, followed generally by rocks on the northeast side of the fault, with the lowest Dd values occurring on the southwest side of the fault. The SRTM data shows a band of high Dd values centered on the main fault trace with ~ 1 km width. Our results indicate that there is a strong correlation between drainage density and proximity to the fault, with zones of structural complexity along the fault displaying the highest Dd. We interpret this to largely be an effect of degree of rock damage, as these are areas that are expected to be more damaged, and field observations support this contention. If we are correct, then it appears that the northeast side of the SJF is generally more damaged. South of the trifurcation area there is evidence that the signal is reversed on the larger scale, with more damage on the southwest side of the fault inferred from the SRTM data, possibly caused by extension between the Coyote Creek and Clark faults. The implications of the observed asymmetry could be geological evidence for rupture propagation

  7. 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.

  8. 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

  9. Learning and diagnosing faults using neural networks

    NASA Technical Reports Server (NTRS)

    Whitehead, Bruce A.; Kiech, Earl L.; Ali, Moonis

    1990-01-01

    Neural networks have been employed for learning fault behavior from rocket engine simulator parameters and for diagnosing faults on the basis of the learned behavior. Two problems in applying neural networks to learning and diagnosing faults are (1) the complexity of the sensor data to fault mapping to be modeled by the neural network, which implies difficult and lengthy training procedures; and (2) the lack of sufficient training data to adequately represent the very large number of different types of faults which might occur. Methods are derived and tested in an architecture which addresses these two problems. First, the sensor data to fault mapping is decomposed into three simpler mappings which perform sensor data compression, hypothesis generation, and sensor fusion. Efficient training is performed for each mapping separately. Secondly, the neural network which performs sensor fusion is structured to detect new unknown faults for which training examples were not presented during training. These methods were tested on a task of fault diagnosis by employing rocket engine simulator data. Results indicate that the decomposed neural network architecture can be trained efficiently, can identify faults for which it has been trained, and can detect the occurrence of faults for which it has not been trained.

  10. 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.

  11. 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.

  12. 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.

  13. Constraining fault friction by re-examining earthquake nodal plane dips

    NASA Astrophysics Data System (ADS)

    Middleton, Timothy A.; Copley, Alex

    2014-02-01

    We have assembled a catalogue of well-constrained focal mechanisms for earthquakes that occurred on continental dip-slip faults that have experienced only small displacements during their current phase of activity. Nodal planes for both reverse- and normal-faulting events are seen to vary between ˜30° and ˜60°, and are concentrated towards the centre of this range. The observed distributions suggest the reactivation of structures with a low coefficient of friction (less than ˜0.3, and possibly as low as ≤0.1). We propose that this low coefficient of friction corresponds to the presence of weak materials in pre-existing fault zones.

  14. Application of damping mechanism model and stacking fault probability in Fe-Mn alloy

    SciTech Connect

    Huang, S.K.; Wen, Y.H.; Li, N. Teng, J.; Ding, S.; Xu, Y.G.

    2008-06-15

    In this paper, the damping mechanism model of Fe-Mn alloy was analyzed using dislocation theory. Moreover, as an important parameter in Fe-Mn based alloy, the effect of stacking fault probability on the damping capacity of Fe-19.35Mn alloy after deep-cooling or tensile deformation was also studied. The damping capacity was measured using reversal torsion pendulum. The stacking fault probability of {gamma}-austenite and {epsilon}-martensite was determined by means of X-ray diffraction (XRD) profile analysis. The microstructure was observed using scanning electronic microscope (SEM). The results indicated that with the strain amplitude increasing above a critical value, the damping capacity of Fe-19.35Mn alloy increased rapidly which could be explained using the breakaway model of Shockley partial dislocations. Deep-cooling and suitable tensile deformation could improve the damping capacity owning to the increasing of stacking fault probability of Fe-19.35Mn alloy.

  15. 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

  16. Long-term changes to river regimes prior to late Holocene coseismic faulting, Canterbury, New Zealand

    NASA Astrophysics Data System (ADS)

    Campbell, Jocelyn K.; Nicol, Andrew; Howard, Matthew E.

    2003-09-01

    Two sites are described from range front faults along the foothills of the Southern Alps of New Zealand, where apparently a period of 200-300 years of accelerated river incision preceded late Holocene coseismic ruptures, each probably in excess of M w 7.5. They relate to separate fault segments and seismic events on a transpressive system associated with fault-driven folding, but both show similar evidence of off-plane aseismic deformation during the downcutting phase. The incision history is documented by the ages, relative elevations and profiles of degradation terraces. The surface dating is largely based on the weathering rind technique of McSaveney (McSaveney, M.J., 1992. A Manual for Weathering-rind Dating of Grey Sandstones of the Torlesse Supergroup, New Zealand. 92/4, Institute of Geological and Nuclear Sciences), supported by some consistent radiocarbon ages. On the Porters Pass Fault, drainage from Red Lakes has incised up to 12 m into late Pleistocene recessional outwash, but the oldest degradation terrace surface T I is dated at only 690±50 years BP. The upper terraces T I and T II converge uniformly downstream right across the fault trace, but by T III the terrace has a reversed gradient upstream. T II and T III break into multiple small terraces on the hanging wall only, close to the fault trace. Continued backtilting during incision caused T IV to diverge downstream relative to the older surfaces. Coseismic faulting displaced T V and all the older terraces by a metre high reverse scarp and an uncertain right lateral component. This event cannot be younger than a nearby ca. 500 year old rock avalanche covering the trace. The second site in the middle reaches of the Waipara River valley involves the interaction of four faults associated with the Doctors Anticline. The main river and tributaries have incised steeply into a 2000 year old mid-Holocene, broad, degradation surface downcutting as much as 55 m. Beginning approximately 600 years ago

  17. Reverse genetics of mononegavirales.

    PubMed

    Conzelmann, K K

    2004-01-01

    "Reverse genetics" or de novo synthesis of nonsegmented negative-sense RNA viruses (Mononegavirales) from cloned cDNA has become a reliable technique to study this group of medically important viruses. Since the first generation of a negative-sense RNA virus entirely from cDNA in 1994, reverse genetics systems have been established for members of most genera of the Rhabdo-, Paramyxo-, and Filoviridae families. These systems are based on intracellular transcription of viral full-length RNAs and simultaneous expression of viral proteins required to form the typical viral ribonucleoprotein complex (RNP). These systems are powerful tools to study all aspects of the virus life cycle as well as the roles of virus proteins in virus-host interplay and pathogenicity. In addition, recombinant viruses can be designed to have specific properties that make them attractive as biotechnological tools and live vaccines. PMID:15298166

  18. Gridded electron reversal ionizer

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara (Inventor)

    1993-01-01

    A gridded electron reversal ionizer forms a three dimensional cloud of zero or near-zero energy electrons in a cavity within a filament structure surrounding a central electrode having holes through which the sample gas, at reduced pressure, enters an elongated reversal volume. The resultant negative ion stream is applied to a mass analyzer. The reduced electron and ion space-charge limitations of this configuration enhances detection sensitivity for material to be detected by electron attachment, such as narcotic and explosive vapors. Positive ions may be generated by generating electrons having a higher energy, sufficient to ionize the target gas and pulsing the grid negative to stop the electron flow and pulsing the extraction aperture positive to draw out the positive ions.

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

    NAS