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Sample records for laguna salada fault

  1. Revisiting the 23 February 1892 Laguna Salada earthquake

    USGS Publications Warehouse

    Hough, S.E.; Elliot, A.

    2004-01-01

    According to some compilations, the Laguna Salada, Baja California, earthquake of 23 February 1892 ranks among the largest earthquakes in California and Baja California in historic times. Although surface rupture was not documented at the time of the earthquake, recent geologic investigations have identified and mapped a rupture on the Laguna Salada fault that can be associated with high probability with the 1892 event (Mueller and Rockwell, 1995). The only intensity-based magnitude estimate for the earthquake, M 7.8, was made by Strand (1980) based on an interpretation of macroseismic effects and a comparison of isoseismal areas with those from instrumentally recorded earthquakes. In this study we reinterpret original accounts of the Laguna Salada earthquake. We assign modified Mercalli intensity (MMI) values in keeping with current practice, focusing on objective descriptions of damage rather than subjective human response and not assigning MMI values to effects that are now known to be poor indicators of shaking level, such as liquefaction and rockfalls. The reinterpreted isoseismal contours and the estimated magnitude are both significantly smaller than those obtained earlier. Using the method of Bakun and Wentworth (1997) we obtain a magnitude estimate of M 7.2 and an optimal epicenter less than 15 km from the center of the mapped Laguna Salada rupture. The isoseismal contours are elongated toward the northwest, which is qualitatively consistent with a directivity effect, assuming that the fault ruptured from southeast to northwest. We suggest that the elongation may also thus reflect wave propagation effects, with more efficient propagation of crustal surface (Lg) waves in the direction of the overall regional tectonic fabric.

  2. Subsidence History of the Laguna Salada Basin in Northeastern Baja California, Mexico

    NASA Astrophysics Data System (ADS)

    Contreras, J.; Martin-Barajas, A.; Herguera, J.

    2008-12-01

    The Salton Trough region in southern California and the Mexicali valley in northwestern Mexico are areas of (i) rapid subsidence due to trans-tension along the San Andreas-Imperial fault system, and (ii) high flux of sediments transported by the Colorado River, all of which confer this region with a high potential to preserve a complete record of climatic and tectonic activity information. Here we present the subsidence history of the Laguna Salada basin, and the history of activity of the master bounding faults on its eastern side. The Laguna Salada is a lacustrine basin located west of the Mexicali valley and to the south of the Salton Trough. Sedimentological as well as time series analyses performed on two 42 m-long cores drilled in the center of the basin, estimated to span the past 50 and 70KaBP, indicate a modulation of the late Quaternary stratigraphy by cyclic variations in lake level driven by Milankovitch forcing. Based on these results we derive the long-term history of the basin from a gamma-ray log recovered from a 2.8 km-deep geothermal borehole drilled by the Mexican Power Company adjacent to the Laguna Salada fault. The stratigraphy of the deep borehole reveals a history of activity pulses related to the initial breakage of the Laguna Salada fault and its interaction with neighboring faults. A first pulse started at 1.5 Ma and records the initiation of the Laguna Salada fault and rapid uplift of the crystalline block of the Sierra Cucapa. A second pulse started around 1 Ma, and is very likely related to the hard linking of the Laguna Salada fault with the Cañada David detachment by the Cañon Rojo fault. The onset of the Laguna Salada fault at 1.5 Ma appears to be synchronous with an early Pleistocene regional fault reorganization among the San Jacinto, San Andreas and Elsinore fault systems in southern California, suggesting that this reorganization may have affected a large area from San Gorgonio pass to the northern Gulf of California.

  3. The Surface Rupture of the 2010 El Mayor-Cucapah Earthquake and its Interaction with the 1892 Laguna Salada Rupture - Complex Fault Interaction in an Oblique Rift System (Invited)

    NASA Astrophysics Data System (ADS)

    Rockwell, T. K.; Fletcher, J. M.; Teran, O.; Mueller, K. J.

    2010-12-01

    The 2010 El Mayor-Cucapah earthquake (Mw 7.2) demonstrates intimate mechanical interactions between two major fault systems that intersect within and along the western margin of the Sierra Cucapah in Baja California, Mexico. Rupture associated with 2010 earthquake produced ~4 m of dextral oblique slip and propagated through an imbricate stack of east-dipping faults. Toward the north, rupture consistently steps left to structurally deeper faults located farther west and in this manner passes through the core of the Sierra Cucapah to its western margin. The western margin of the Sierra Cucapah is defined by the Laguna Salada fault (LSF), which forms part of an active west-directed oblique detachment system recognized as the source of the large (M7+) February 22, 1892 earthquake. In the central Sierra Cucapah, the fault systems are separated by a narrow horst block, and here the 2010 event produced triggered slip on the LSF. These surface breaks follow the exact trace of the 1892 rupture, but their sense of slip (10-30 cm of pure normal displacement) differs radically from the 5 m of oblique dextral-normal slip produced by the 1892 event. Farther north, the narrow horst block is buried beneath strata of the northern Laguna Salada rift basin, and at this location, west-directed scarps of the LSF accommodate a significant component of dextral slip associated with the primary 2010 surface rupture. Thus, the two fault systems combine to accommodate oblique extension in the northern part of the range and likely have linking structures at fairly shallow depth. Newly identified paleo-scarps extend the known 1892 rupture length from 20 km to as much as 42 km, from the Canon Rojo fault to the Yuha Basin; consistent with a Mw 7.2 event and historical reports of MMI VII damage in San Diego. Both fault systems generate large earthquakes (>M7.2), with the west-directed LSF fault accommodating rapid subsidence in the adjacent basin during M7+ events at ~ 2Ka recurrence. Initial

  4. Late Neogene stratigraphy and tectonic control on facies evolution in the Laguna Salada Basin, northern Baja California, Mexico

    NASA Astrophysics Data System (ADS)

    Martín-Barajas, A.; Vázquez-Hernández, S.; Carreño, A. L.; Helenes, J.; Suárez-Vidal, F.; Alvarez-Rosales, J.

    2001-10-01

    The Laguna Salada Basin (LSB) in northeastern Baja California records late-Neogene marine incursions in the Salton Trough and progradation of the Colorado River delta. Early subsidence and subsequent tectonic erosion are related to evolution of the Sierra El Mayor detachment fault during late Miocene time (<12 Ma). The stratigraphy of uplifted blocks on the east-central margin of the Laguna Salada Basin and from three exploratory wells allows reconstruction of the main sedimentary and tectonic events. Marine mudstone and sandstone, and subordinate conglomerate of the Imperial Formation tectonically overlie metamorphic and granitic basement. Microfossils, lithology, and sedimentary structures in the Imperial Formation define Upper Miocene (<6 Ma) outer-shelf facies that grade up-section into inner-shelf and tide-dominated delta plain deposits of the ancient Colorado River. Lower Pliocene (˜4-2 Ma) reddish, sub-arkosic fluvial sandstone and siltstone of the Palm Spring Formation defines progradation of non-marine fluvio-deltaic deposits over the marine Imperial Formation. Continuous outcrops of the Palm Spring are less than 170-m thick, but correlative deposits are more than 570 m thick in the lower part of a 2400-m deep geothermal exploratory well on the eastern margin of LSB. Interfingering fluvial-sandstone deposits and prograding alluvial fanglomerates with coarse debris-flow and rock-avalanche deposits crudely mark the onset of vertical slip along the Laguna Salada fault and rapid uplift of Sierra Cucapa and Sierra El Mayor. Up to 2 km of Quaternary alluvial-fan and lacustrine deposits accumulated along the eastern margin of LSB, whereas lower subsidence rates produced a thinner sedimentary wedge over a ramp-like crystalline basement along the western margin. In early Pleistocene time (˜2-1 Ma), the Laguna Salada became progressively isolated from the Colorado River delta complex, and the Salton Trough by activity on the Elsinore and Laguna Salada fault zones.

  5. Ostracode Paleoecology and Trace Element Shell Chemistry: A case study from Laguna Salada, Baja California, Mexico.

    NASA Astrophysics Data System (ADS)

    Romero-Mayen, V.; Bernal, J.; Palacios-Fest, M.; Carreno, A.

    2007-05-01

    The Laguna Salada Basin in northeastern Baja California constitutes the southwestern limit of the Salton Trough and provides insights into the evolution of marine and non-marine sedimentary basins during the latest Neogene at the head of the Gulf of California. A 43 m long core (LS04-1) recovered from the Basin consisted of alternating clay, silt and sand beds with gypsum lenses. Three radiocarbon dates provided the age control: 41,520±790 cal years BP at 30.21 m, 25,590±320 cal years BP at 26.60 m and 15,150±70 cal years BP at 7.50 m. A total of 103 samples were analyzed for taxonomy, taphonomy and geochemistry. Eighteen marine and brackish- water ostracode species and nine benthic foraminifera species were identified. Faunal changes suggest variations in the water source with the opening of the basin to the Gulf of California. The Mg/Ca and Sr/Ca ratios of valves of two ostracode species (Limnocythere staplini and Cyprideis castus) were measured using ICPMS. Based on the Mg/Ca ratios, water paleotemperatures were estimated using a regression model. Shell chemistry shows mixed results. Some intervals fit an acceptable range, whereas other are unrealistic. Analysis of Sr/Ca ratios ostracode valves from the conflicting horizons show evidence of diagenetic effects. The fossil assemblages indicate two dry periods: prior to the 41,520 cal years BP and after the 15 ,150 cal years BP, with the maximum highstand of the basin between 25,590 and 15,150 cal years BP. Given the diagenetic effects at Laguna Salada, ostracode shell chemistry paleotemperature estimates may not be warranted in attempting to determine this parameter from the dry periods shown by faunal assemblages.

  6. Long period variability of a High Resolution Hydraulic Balance Proxy for Southern California and Northwestern Mexico: A 50 ka-long Sediment Record from Laguna Salada Basin, Baja California, Mexico

    NASA Astrophysics Data System (ADS)

    Aco-Palestina, A.; Contreras, J.; Martin-Barajas, A.; Hergeura, J. C.; Rendon-Marquez, G.

    2005-12-01

    The Salton Trough region of southern California and the Mexicali valley in northwestern Mexico are areas of rapid subsidence due to extension along the San Andreas-Imperial fault system and are being filled by clastic sediments transported by the Colorado River. The relatively high sedimentation rates of these basins have a high potential to preserve high-resolution climatic information. With this goal in mind, we drilled a 42 m-long core in the center of the Laguna Salada, a lacustrine basin located west of the Mexicali valley and to the south of the Salton Trough. Two 14C dates from plant remnants indicate sedimentation rates are in the order of 1mm/yr; based on this we estimate the age of the bottom of the core close to 50 Ka. This high sedimentation rate could in principle allow us to reconstruct the climatic variability of this hyperarid region on timescales ranging from centennial and millennial periodicities up to Milankovitch forcing. Here we present data on the first-order changes introduced by the later longer periods. Sedimentary facies in the core were identified based on color, granulometry, mineralogical composition and primary structures such as laminations, dissecation cracks, and bioturbation. Additionally, we obtained reflectivity of sediments every 5 mm to 1 cm, depending on the scale of primary structures. The recovered stratigraphy consists of three sedimentary successions. The lower part of the core is characterized by an alternation of mud and silt laminae of varying thickness between 5mm-1cm, probably deposited during stage 3. This ancient paleolake was dominated by sub-aqueous conditions with a permanent water table year-round. Good preservation of laminae suggests seasonal bottom anoxia. During the last glacial maximum, moisture conditions changed drastically. Laminations are replaced by finely stratified sand and further upsection by repetitive packages 50cm-thick composed of fine sand, brown mud, greenish silt and mud, and mud, caped

  7. Recovering the Linkage History of Large Faults from the Sediments of the Gulf of California Extensional Province

    NASA Astrophysics Data System (ADS)

    Contreras, J.; Martin-Barajas, A.; Herguera, J.; Dorsey, R.

    2003-12-01

    Analysis of the stratigraphy of sedimentary basins bounded by normal faults yield a wealth of information about how these brittle structures evolve through time forming array systems. However, mostly due to large uncertainties in the dating of sediments, little can be said about slip rates and how slip is accommodated during the interaction and linkage of normal faults. Cyclicity in sediments induced by Milankovitch climatic changes can be used as a very precise high-resolution stratigraphic chronometer, eliminating the problem of uncertainties in the dating. Therefore, the slip history of faults can be inferred with high accuracy. Here we present a cyclicity analysis of gamma-ray log from a borehole drilled in the Laguna Salada basin, a transtensional basin located in the Gulf of California extensional province. This has allowed us to establish its chronostratigraphy with a resolution of 50 kyr, from which the subsidence history of the Laguna Salada fault and its interaction with neighboring faults is recovered. We find that the long-term subsidence rate of the Laguna Salada basin has remained constant during the last 1.65 Ma (~1.4 mm/yr) in agreement with observations documented by other authors. However, our analysis reveals that at shorter timescales the subsidence history is composed of pulses lasting on average ~500 kyr. Subsidence rates during these pulses can vary by a factor of two with respect to the long-term subsidence rate. These pulses correlate with the breaking of the Laguna Salada Fault and the breaking of the Canon Rojo fault, a releasing stepover that links the Laguna Salada fault with the Canada David detachment to the south.

  8. Distributed fault rupture in the Yuha Desert, California, associated with the El Mayor-Cucapah earthquake, and the contribution of InSAR imagery to its documentation

    NASA Astrophysics Data System (ADS)

    Treiman, J. A.; Kendrick, K. J.; Rymer, M. J.; Fielding, E. J.

    2010-12-01

    The Mw7.2 April 4, 2010 El Mayor-Cucapah earthquake and its aftershocks caused primary and secondary rupture on a broad array of more than two dozen faults in the Yuha Desert, just north of the United States-Mexico border. Field mapping documented maximum displacements of 4-6 cm on branches of the northwest-trending Laguna Salada Fault and on the newly identified and named, northeast-trending Yuha Fault. Lesser displacements, including left-lateral, right-lateral and/or extensional components were mapped on at least twenty other faults, a majority of which are newly identified. Minor triggered slip (~1 cm) was also found on the southeastern-most Elsinore Fault, likely in response to the June aftershock sequence. Although the principal faults were readily identified and mapped in the field, many of the faults with lower coseismic displacement might not have been mapped had we not had interferometric synthetic aperture radar (InSAR) imagery to alert us to their presence. InSAR images were from data derived from the high resolution airborne NASA/JPL UAVSAR instrument. Fault displacements were discernable from both the primary rupture and the aftershock sequence. Faults with surface displacements as small as a couple of millimeters or less were located and mapped. Several InSAR lineaments are interpreted as faults which had more distributed displacement that was not expressed as brittle surface rupture. InSAR imagery spanning the appropriate time intervals proved invaluable to obtaining a more complete picture of faulting in the Yuha Desert.

  9. Diversity of halophilic bacteria isolated from Rambla Salada, Murcia (Spain).

    PubMed

    Luque, Rocío; Béjar, Victoria; Quesada, Emilia; Llamas, Inmaculada

    2014-12-01

    In this study we analyzed the diversity of the halophilic bacteria community from Rambla Salada during the years 2006 and 2007. We collected a total of 364 strains, which were then identified by means of phenotypic tests and by the hypervariable V1-V3 region of the 16S rRNA sequences (around 500 bp). The ribosomal data showed that the isolates belonged to Proteobacteria (72.5%), Firmicutes (25.8%), Actinobacteria (1.4%), and Bacteroidetes (0.3%) phyla, with Gammaproteobacteria the predominant class. Halomonas was the most abundant genus (41.2% isolates) followed by Marinobacter (12.9% isolates) and Bacillus (12.6% isolates). In addition, 9 strains showed <97% sequence identity with validly described species and may well represent new taxa. The diversity of the bacterial community analyzed with the DOTUR package determined 139 operational taxonomic units at 3% genetic distance level. Rarefaction curves and diversity indexes demonstrated that our collection of isolates adequately represented all the bacterial community at Rambla Salada that can be grown under the conditions used in this work. We found that the sampling season influenced the composition of the bacterial community, and bacterial diversity was higher in 2007; this fact could be related to lower salinity at this sampling time.

  10. The Pueblo of Laguna.

    ERIC Educational Resources Information Center

    Lockart, Barbetta L.

    Proximity to urban areas, a high employment rate, development of natural resources and high academic achievement are all serving to bring Laguna Pueblo to a period of rapid change on the reservation. While working to realize its potential in the areas of natural resources, commercialism and education, the Pueblo must also confront the problems of…

  11. 'Laguna Hollow'Undisturbed

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image shows the patch of soil at the bottom of the shallow depression dubbed 'Laguna Hollow' where the Mars Exploration Rover Spirit will soon begin trenching. Scientists are intrigued by the clustering of small pebbles and the crack-like fine lines, which indicate a coherent surface that expands and contracts. A number of processes can cause materials to expand and contract, including cycles of heating and cooling; freezing and thawing; and rising and falling of salty liquids within a substance. This false-color image was created using the blue, green and infrared filters of the rover's panoramic camera. Scientists chose this particular combination of filters to enhance the heterogeneity of the martian soil.

  12. The LAGUNA-LBNO Project

    NASA Astrophysics Data System (ADS)

    Avanzini, Margherita Buizza

    LAGUNA-LBNO is a Design Study funded by the European Commission to develop the design of a large and deep underground neutrino observatory; its physics program involves the study of neutrino oscillations at long baselines, the investigation of the Grand Unification of elementary forces and the detection of neutrinos from astrophysical sources. Building on the successful format and on the findings of the previous LAGUNA Design Study, LAGUNA-LBNO is more focused and is specifically considering Long Baseline Neutrino Oscillations (LBNO) with neutrino beams from CERN. Two sites, Fréjus (in France at 130 km) and Pyhäsalmi (in Finland at 2300 km), are being considered. Three different detector technologies are being studied: Water Cherenkov, Liquid Scintillator and Liquid Argon. Recently the LAGUNA-LBNO consortium has submitted an Expression of Interest for a very long baseline neutrino experiment, selecting as a first priority the option of a Liquid Argon detector at Pyhäsalmi. Detailed potential studies have been curried out for the determination of the neutrino Mass Hierarchy and the discovery of the CP-violation, using a conventional neutrino beam from the CERN SPS with a power of 750 kW.

  13. Provenance of alluvial fan deposits to constrain the mid-term offsets along a strike-slip active fault: the Elsinore fault in the Coyote Mountains, Imperial Valley, California.

    NASA Astrophysics Data System (ADS)

    Masana, Eulalia; Stepancikova, Petra; Rockwell, Thomas

    2013-04-01

    The lateral variation in rates along a fault and its constancy along time is a matter of discussion. To give light to this discussion, short, mid and long term offset distribution along a fault is needed. Many studies analyze the short-term offset distribution along a strike-slip fault that can be obtained by the analysis of offset features imprinted in the morphology of the near-fault area. We present an example on how to obtain the mid- to long-term offset values based on the composition of alluvial fans that are offset by the fault. The study area is on the southern tip of the Elsinore fault, which controls the mountain front of the Coyote Mountains (California). The Elsinore-Laguna Salada fault is part of the San Andreas fault (SAF) system, extending 250 km from the Los Angeles Basin southeastward into the Gulf of California, in Mexico. The slip-rate on the southern Elsinore fault is believed to be moderate based on recent InSAR observations, although a recent study near Fossil Canyon (southern Coyote Mountains) suggests a rate in the range of 1-2 mm/yr. For this study we processed the airborne LiDAR dataset (EarthScope Southern & Eastern California, SoCal) to map short to mid-term alluvial offsets. We reprocessed the point clouds to produce DEMs with 0.5m and 0.25m grids and we varied the insolation angles to illuminate the various fault strands and the offset features. We identified numerous offset features, such as rills, channel bars, channel walls, alluvial fans, beheaded channels and small erosional basins that varied in displacement from 1 to 350 m. For the mid- to long-term offsets of the alluvial fans we benefited from the diverse petrological composition of their sources. Moreover, we recognized that older alluvium, which is offset by greater amounts, is in some cases buried beneath younger alluvial fan deposits and separated by buried soils. To determine the source canyon of various alluvial elements, we quantified the clast assemblage of each source

  14. Bloedite sedimentation in a seasonally dry saline lake (Salada Mediana, Spain)

    NASA Astrophysics Data System (ADS)

    Mees, Florias; Castañeda, Carmen; Herrero, Juan; Van Ranst, Eric

    2011-06-01

    Salt crusts covering the surface of the Salada Mediana, a seasonally dry saline lake in northern Spain, consist predominantly of bloedite (Na 2Mg(SO 4) 2.4H 2O). Microscopic features of the crust were investigated to understand processes of bloedite sedimentation. This study was combined with satellite and airborne observations, revealing asymmetrical concentric and parallel-linear patterns, related to wind action. Gypsum (CaSO 4.H 2O) and glauberite (Na 2Ca(SO 4) 2) in the calcareous sediments below the crust, and abundant eugsterite (Na 4Ca(SO 4) 3.2H 2O) along the base of the crust, largely formed at a different stage than bloedite. The main part of the crust consists predominantly of coarse-crystalline xenotopic-hypidiotopic bloedite, but fan-like aggregates with downward widening, radial aggregates, surface layers with vertically aligned elongated crystals, and partially epitaxial coatings occur as well. The upper part of the crust is marked by a bloedite-thenardite (Na 2SO 4) association, recording a change in brine composition that is not in agreement with results of modelling of local brine evolution. A thin fine-grained thenardite-dominated surface formed in part by subaqueous settling of crystals, but there are also indications for development by transformation of bloedite. Surface features include fan-like bloedite aggregates with upward widening, formed by bottom growth. Overall, the Salada Mediana crusts record a complex history of bloedite and thenardite precipitation by various processes.

  15. Present-day loading rate of faults in southern California and northern Baja California, Mexico, and post-seismic deformation following the M7.2 April 4, 2010, El Mayor-Cucapah earthquake from GPS Geodesy

    NASA Astrophysics Data System (ADS)

    Spinler, J. C.; Bennett, R. A.

    2012-12-01

    the west of the Laguna Salada fault zone are moving more westerly. Sites to the east of the EMC rupture move more southerly than prior to the EMC earthquake. Continued monitoring of these velocity changes will allow us to differentiate between lower crustal and upper mantle relaxation processes.

  16. Tectonic forcing of shelf-ramp depositional architecture, Laguna Madre-Tuxpan Shelf, western Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Wawrzyniec, Tim F.; Ambrose, W.; Aranda-Garcia, M.; Romano, U. H.

    2004-07-01

    Analysis of seismic reflection data reveals the existence of a major listric fault that accommodates most of the Neogene extension of the Laguna Madre-Tuxpan shelf of the western Gulf of Mexico. The variation of related growth strata, the profile of the modern shelf-slope transition, the linear gradient of shelf extension (as well as basin accommodation) along the trace of the fault support a hypothesis that sediment loading along the northern part of the fault drives fault motion and influences sediment distribution along the southern end of the fault. In particular, where kinematic accommodation appears to outpace sediment supply, sedimentation is maximized along a shelf-ramp system and not the shelf-slope transition.

  17. Santa Fe Indian Camp, House 21, Richmond, California: Persistence of Identity among Laguna Pueblo Railroad Laborers, 1945-1982.

    ERIC Educational Resources Information Center

    Peters, Kurt

    1995-01-01

    In 1880 the Laguna people and the predecessor of the Atchison, Topeka, and Santa Fe Railroad reached an agreement giving the railroad unhindered right-of-way through Laguna lands in exchange for Laguna employment "forever." Discusses the Laguna-railroad relationship through 1982, Laguna labor camps in California, and the persistence of…

  18. Field reconnaissance of the effects of the earthquake of April 13, 1973, near Laguna de Arenal, Costa Rica

    USGS Publications Warehouse

    Plafker, George

    1973-01-01

    At about 3:34 a.m. on April 13, 1973, a moderate-sized, but widely-felt, earthquake caused extensive damage with loss of 23 lives in a rural area of about 150 km2 centered just south of Laguna de Arenal in northwestern Costa Rica (fig. 1). This report summarizes the results of the writer's reconnaissance investigation of the area that was affected by the earthquake of April 13, 1973. A 4-day field study of the meizoseismal area was carried out during the period from April 28 through May 1 under the auspices of the U.S. Geological Survey. The primary objective of this study was to evaluate geologic factors that contributed to the damage and loss of life. The earthquake was also of special interest because of the possibility that it was accompanied by surface faulting comparable to that which occurred at Managua, Nicaragua, during the disastrous earthquake of December 23, 1972 (Brown, Ward, and Plafker, 1973). Such earthquake-related surface faulting can provide scientifically valuable information on active tectonic processes at shallow depths within the Middle America arc. Also, identification of active faults in this area is of considerable practical importance because of the planned construction of a major hydroelectrical facility within the meizoseismal area by the Instituto Costarricense de Electricidad (I.C.E.). The project would involve creation of a storage reservoir within the Laguna de Arenal basin and part of the Río Arenal valley with a 75 m-high earthfill dam across Río Arenal at a point about 10 km east of the outlet of Laguna de Arenal.

  19. Limnology of Laguna Tortuguero, Puerto Rico

    USGS Publications Warehouse

    Quinones-Marquez, Ferdinand; Fuste, Luis A.

    1978-01-01

    The principal chemical, physical and biological characteristics, and the hydrology of Laguna Tortuguero, Puerto Rico, were studied from 1974-75. The lagoon, with an area of 2.24 square kilometers and a volume of about 2.68 million cubic meters, contains about 5 percent of seawater. Drainage through a canal on the north side averages 0.64 cubic meters per second per day, flushing the lagoon about 7.5 times per year. Chloride and sodium are the principal ions in the water, ranging from 300 to 700 mg/liter and 150 to 400 mg/liter, respectively. Among the nutrients, nitrogen averages about 1.7 mg/liter, exceeding phosphorus in a weight ratio of 170:1. About 10 percent of the nitrogen and 40 percent of the phosphorus entering the lagoon is retained. The bottom sediments, with a volume of about 4.5 million cubic meters, average 0.8 and 0.014 percent nitrogen and phosphorus, respectively. (Woodard-USGS)

  20. 77 FR 49455 - Proclaiming Certain Lands as an Addition to and Becoming a Part of the Laguna Reservation for the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-16

    ... Reservation for the Pueblo of Laguna, NM AGENCY: Bureau of Indian Affairs, Interior. ACTION: Notice of... the Pueblo of Laguna Indian Reservation for the Pueblo of Laguna, New Mexico. FOR FURTHER INFORMATION... be the Pueblo of Laguna Indian Reservation for the exclusive use of Indians on that reservation...

  1. Hydrology of Laguna Joyuda, Puerto Rico

    USGS Publications Warehouse

    Santiago-Rivera, Luis; Quinones-Aponte, Vicente

    1995-01-01

    A study was conducted by the U.S. Geological Survey to define the hydraulic and hydrologic characteristics of the Laguna Joyuda system (in southwestern Puerto Rico) and to determine the water budget of the lagoon. This shallow-water lagoon is connected to the sea by a single canal. Rainfall and evaporation, surface-water, groundwater, and tidal-flow data were collected from December 1, 1985, to April 30, 1988. A conceptual hydrologic model of the lagoon was developed and discharge measurements and modeling were undertaken to quantify the different flow components. The water balance during the 29-month study period was determined by measuring and estimating the different hydrologic components: 4.14 million cubic meters rainfall; 5.38 million cubic meters evaporation; 1.1 8 million cubic meters surface water; and 0.34 million cubic meters ground water. A total of 18.9 million cubic meters ebb flow (tidal outflow) was discharged from the lagoon and 14.4 million cubic meters flood flow (tidal inflow) entered through the canal during the study. Seawater inflow accounted for 71 percent of the water into the lagoon. The storage volume of the lagoon was about 1.55 million cubic meters. The lagoon's hydrologic-budget residual was 4.22 million cubic meters, whereas the sum of the estimated errors for the different hydrologic components amounted to 4.51 million cubic meters. Average flushing rate for the lagoon was estimated at 72 days. During the study, the specific conductance of the lagoon water ranged from 32,000 to 52,000 microsiemens per centimeter at 25 degrees Celsius, whereas the specific conductance of local seawater is about 45,000 to 55,000 microsiemens.

  2. MTADS Live Site Demonstration, Pueblo of Laguna, NM

    DTIC Science & Technology

    1998-08-07

    survived De Vargas’ attack on their stronghold at La Cienequilla in 1694. The Pueblo had its grant confirmed by the Treaty of Guadalupe Hidalgo in...16.6 Field Suppor t Labor Laguna Industr ies 6.6 Tent Garcia Rentals 2.6 Portable Toilets Sani tary Service Co. 0.8 Water Dawson Water & Ice 0.4

  3. Molecular Epidemiology of Laguna Negra Virus, Mato Grosso State, Brazil

    PubMed Central

    Travassos da Rosa, Elizabeth S.; Medeiros, Daniele B.A.; Nunes, Márcio R.T.; Simith, Darlene B.; Pereira, Armando de S.; Elkhoury, Mauro R.; Santos, Elizabeth Davi; Lavocat, Marília; Marques, Aparecido A.; Via, Alba V.G.; Kohl, Vânia A.; Terças, Ana C.P.; D`Andrea, Paulo; Bonvícino, Cibele R.; Sampaio de Lemos, Elba R.

    2012-01-01

    We associated Laguna Negra virus with hantavirus pulmonary syndrome in Mato Grosso State, Brazil, and a previously unidentified potential host, the Calomys callidus rodent. Genetic testing revealed homologous sequencing in specimens from 20 humans and 8 mice. Further epidemiologic studies may lead to control of HPS in Mato Grosso State. PMID:22607717

  4. The Optometry Program at Universidad Autonoma de la Laguna, Mexico.

    ERIC Educational Resources Information Center

    Gonzalez, Agustin L.

    1995-01-01

    A description of the optometry program at the Universidad Autonoma de la Laguna (Mexico) provides information on the composition of the faculty, design of the five-year program as compared with the traditional four-year program, curriculum content, clinical education, visiting lecturer program, and certification of graduates. (MSE)

  5. Interacting faults

    NASA Astrophysics Data System (ADS)

    Peacock, D. C. P.; Nixon, C. W.; Rotevatn, A.; Sanderson, D. J.; Zuluaga, L. F.

    2017-04-01

    The way that faults interact with each other controls fault geometries, displacements and strains. Faults rarely occur individually but as sets or networks, with the arrangement of these faults producing a variety of different fault interactions. Fault interactions are characterised in terms of the following: 1) Geometry - the spatial arrangement of the faults. Interacting faults may or may not be geometrically linked (i.e. physically connected), when fault planes share an intersection line. 2) Kinematics - the displacement distributions of the interacting faults and whether the displacement directions are parallel, perpendicular or oblique to the intersection line. Interacting faults may or may not be kinematically linked, where the displacements, stresses and strains of one fault influences those of the other. 3) Displacement and strain in the interaction zone - whether the faults have the same or opposite displacement directions, and if extension or contraction dominates in the acute bisector between the faults. 4) Chronology - the relative ages of the faults. This characterisation scheme is used to suggest a classification for interacting faults. Different types of interaction are illustrated using metre-scale faults from the Mesozoic rocks of Somerset and examples from the literature.

  6. Port Isabel (GIWW) Channel Improvements at the Queen Isabella Causeway. Laguna Madre, Texas, Navigation Improvement Project

    DTIC Science & Technology

    2009-09-01

    ER D C/ CH L TR -0 9 -1 3 Port Isabel (GIWW) Channel Improvements at the Queen Isabella Causeway Laguna Madre , Texas, Navigation...Causeway Laguna Madre , Texas, Navigation Improvement Project Timothy W. Shelton, P.E. and Dennis Webb, P.E. Coastal and Hydraulics Laboratory U.S...distribution is unlimited. Prepared for U.S. Army Corps of Engineer District, Galveston Galveston, TX 77550 ERDC/CHL TR-09-13 ii Abstract: Laguna Madre is

  7. 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.

  8. Quaternary pollen record from laguna de tagua tagua, chile.

    PubMed

    Heusser, C J

    1983-03-25

    Pollen of southern beech and podocarp at Laguna de Tagua Tagua during the late Pleistocene indicates that cooler and more humid intervals were a feature of Ice Age climate at this subtropical latitude in Chile. The influence of the southern westerlies may have been greater at this time, and the effect of the Pacific anticyclone was apparently weakened. The climate today, wet in winter and dry in summer, supports broad sclerophyll vegetation that developed during the Holocene with the arrival of paleo-Indians and the extinction of mastodon and horse.

  9. Possibilities For The LAGUNA Projects At The Frejus Site

    SciTech Connect

    Mosca, Luigi

    2010-11-24

    The present laboratory (LSM) at the Frejus site and the project of a first extension of it, mainly aimed at the next generation of dark matter and double beta decay experiments, are briefly reviewed. Then the main characteristics of the LAGUNA cooperation and Design Study network are summarized. Seven underground sites in Europe are considered in LAGUNA and are under study as candidates for the installation of Megaton scale detectors using three different techniques: a liquid Argon TPC (GLACIER), a liquid scintillator detector (LENA) and a Water Cerenkov (MEMPHYS), all mainly aimed at investigation of proton decay and properties of neutrinos from SuperNovae and other astrophysical sources as well as from accelerators (Super-beams and/or Beta-beams from CERN). One of the seven sites is located at Frejus, near the present LSM laboratory, and the results of its feasibility study are presented and discussed. Then the physics potential of a MEMPHYS detector installed in this site are emphasized both for non-accelerator and for neutrino beam based configurations. The MEMPHYNO prototype with its R and D programme is presented. Finally a possible schedule is sketched.

  10. Fault Branching

    NASA Astrophysics Data System (ADS)

    Dmowska, R.; Rice, J. R.; Poliakov, A. N.

    2001-12-01

    Theoretical stress analysis for a propagating shear rupture suggests that the propensity of the rupture path to branch is determined by rupture speed and by the preexisting stress state. See Poliakov, Dmowska and Rice (JGR, submitted April 2001, URL below). Deviatoric stresses near a mode II rupture tip are found to be much higher to both sides of the fault plane than directly ahead, when rupture speed becomes close to the Rayleigh speed. However, the actual pattern of predicted Coulomb failure on secondary faults is strongly dependent on the angle between the fault and the direction of maximum compression Smax in the pre-stress field. Steep Smax angles lead to more extensive failure on the extensional side, whereas shallow angles give comparable failure regions on both. Here we test such concepts against natural examples. For crustal thrust faults we may assume that Smax is horizontal. Thus nucleation on a steeply dipping plane, like the 53 ° dip for the 1971 San Fernando earthquake, is consistent with rupture path kinking to the extensional side, as inferred. Nucleation on a shallow dip, like for the 12 ° -18 ° of the 1985 Kettleman Hills event, should activate both sides, as seems consistent with aftershock patterns. Similarly, in a strike slip example, Smax is inferred to be at approximately 60 ° with the Johnson Valley fault where it branched to the extensional side onto the Landers-Kickapoo fault in the 1992 event, and this too is consistent. Further, geological examination of the activation of secondary fault features along the Johnson Valley fault and the Homestead Valley fault consistently shows that most activity occurs on the extensional side. Another strike-slip example is the Imperial Valley 1979 earthquake. The approximate Smax direction is north-south, at around 35 ° with the main fault, where it branched, on the extensional side, onto Brawley fault, again interpretable with the concepts developed.

  11. Focal Mechanisms for Local Earthquakes within a Rapidly Deforming Rhyolitic Magma System, Laguna del Maule, Chile

    NASA Astrophysics Data System (ADS)

    Peterson, D. E.; Keranen, K. M.; Cardona, C.; Thurber, C. H.; Singer, B. S.

    2015-12-01

    Large shallow rhyolitic magma systems like the one underlying the Laguna del Maule Volcanic Field (LdM) atop the Southern Andes, Chile, that comprises the largest concentration of rhyolitic lava and tephra younger than 20 ka at earth's surface, are capable of producing modest to very large explosive eruptions. Moreover, LdM is currently exhibiting magma migration, reservoir growth, and crustal deformation at rates higher than any volcano that is not actively erupting. The long-term build-up of a large silicic magmatic system toward an eruption has yet to be monitored, therefore, precursory phenomena are poorly understood. In January of 2015, 12 broadband, 3-component seismometers were installed at LdM to detect local microearthquakes and tele-seismic events with the goals of determining the migration paths of fluids as well as the boundaries of the magma chamber beneath LdM. These stations complement the 6 permanent stations installed by the Southern Andes Volcano Observatory in 2011. Focal mechanisms were calculated using FOCMEC (Snoke et al., 1984) and P-wave first motions for local events occurring between January and March of 2015 using these 18 broadband stations. Results from six of the largest local events indicate a mixture of normal and reverse faulting at shallow (<10 km) depths surrounding the lake. This may be associated with the opening of fractures to accommodate rising magma in the subsurface and/or stresses induced by the rapid deformation. Two of these events occurred near the center of maximum deformation where seismic swarms have previously been identified. Focal mechanisms from smaller magnitude events will be calculated to better delineate subsurface structure. Source mechanisms will be refined using P-S amplitude ratios and full waveform inversion.

  12. 76 FR 24512 - Laguna Cartagena National Wildlife Refuge, Lajas, Puerto Rico; Draft Comprehensive Conservation...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-02

    ... Fish and Wildlife Service Laguna Cartagena National Wildlife Refuge, Lajas, Puerto Rico; Draft Comprehensive Conservation Plan and Environmental Assessment AGENCY: Fish and Wildlife Service, Interior. ACTION: Notice of availability; request for comments. SUMMARY: We, the Fish and Wildlife Service...

  13. 78 FR 57545 - Proposed Establishment of Class D Airspace and Class E Airspace; Laguna AAF, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-19

    .... An informal docket may also be examined during normal business hours at the Northwest Mountain... extending upward from 700 feet or more above the surface of the earth. * * * * * AWP AZ E5 Laguna AAF,...

  14. About a Gadolinium-doped Water Cherenkov LAGUNA Detector

    SciTech Connect

    Labarga, Luis

    2010-11-24

    Water Cherenkov (wC) detectors are extremely powerful apparatuses for scientific research. Nevertheless they lack of neutron tagging capabilities, which translates, mainly, into an inability to identify the anti-matter nature of the reacting incoming anti-neutrino particles. A solution was proposed by R. Beacon and M. Vagins back in 2004: by dissolving in the water a compound with nucleus with very large cross section for neutron capture like the Gadolinium, with a corresponding emission of photons of enough energy to be detected, they can tag thermal neutrons with an efficiency larger than 80%. In this talk we detail the technique and its implications in the measurement capabilities and, as well, the new backgrounds induced. We discuss the improvement on their physics program, also for the case of LAGUNA type detectors. We comment shortly the status of the pioneering R and D program of the Super-Kamiokande Collaboration towards dissolving a Gadolinium compound in its water.

  15. Condensate polisher prefiltration study for Laguna Verde Station

    SciTech Connect

    Garcia, A.; Oyen, L.C.; Nelson, R.A.

    1995-05-01

    This paper describes an analysis of the iron and copper in the condensate and the technical and economic assessment of the installation of condensate polisher prefilters in Comision Federal de Electricidad`s Laguna Verde Nuclear Generating Station (LVNGS) north of Veracruz, Mexico. LVNGS is a 654 MWe General Electric BWR plant; Unit 1 has been in commercial operation since July, 1990, and Unit 2 is scheduled to become operational in June, 1995. The primary purpose of this study was to (1) analyze the high iron and copper concentrations in the condensate and feedwater, (2) identify, assess, and evaluate techniques to reduce the iron and copper concentrations, and (3) perform a cost-benefit analysis of the installation of implementing the appropriate techniques.

  16. Level-2 IPE for the Laguna Verde NPS

    SciTech Connect

    Arellano, J.; De Loera, M.A.; Rea, R.

    1996-12-31

    In response to generic letter GL 88-20, Comision Federal de Electricidad and Instituto de Investigaciones Electricas have jointly developed the individual plant examination (IPE) for the Laguna Verde nuclear power station unit I (LVNPS). This plant is a 675-MW(electric) boiling water reactor (BWR/5) with a reinforced concrete Mark-II containment. The approach used to fulfill the IPE requirements was to make a level-1 probabilistic risk assessment (IPE level 1) plus a containment performance analysis including the behavior and release of the fission products to the environment (IPE level 2). This paper describes the level-2 portion of the LVNPS IPE, paying special attention to both some improvements to the traditional analytical methods and to the main results.

  17. Fault diagnosis

    NASA Technical Reports Server (NTRS)

    Abbott, Kathy

    1990-01-01

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

  18. Andrés Laguna: a great medical humanist (1499-1559).

    PubMed

    Kousoulis, Antonis A; Karamanou, Marianna; Androutsos, George

    2011-01-01

    Andrés Laguna, a Spanish humanist physician of the 16th century, occupies an important position in the history of medicine. An illustrious and brilliant mind, pioneer of anatomy and urology, Laguna proved to be a true pacifist and humanitarian with his knowledge standards and his political eloquence. He deserves to be remembered today as the perfect example of the Renaissance men, a true Homo Universalis.

  19. Hatching success of Caspian terns nesting in the lower Laguna Madre, Texas, USA

    USGS Publications Warehouse

    Mitchell, C.A.; Custer, T.W.

    1986-01-01

    The average clutch size of Caspian Terns nesting in a colony in the Lower Laguna Madre near Laguna Vista, Texas, USA in 1984 was 1.9 eggs per nest. Using the Mayfield method for calculating success, one egg hatched in 84.1% of the nests and 69.8% of the eggs laid hatched. These hatching estimates are as high or higher than estimates from colonies in other areas.

  20. 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.

  1. Factors controlling navigation-channel Shoaling in Laguna Madre, Texas

    USGS Publications Warehouse

    Morton, R.A.; Nava, R.C.; Arhelger, M.

    2001-01-01

    Shoaling in the Gulf Intracoastal Waterway of Laguna Madre, Tex., is caused primarily by recycling of dredged sediments. Sediment recycling, which is controlled by water depth and location with respect to the predominant wind-driven currents, is minimal where dredged material is placed on tidal flats that are either flooded infrequently or where the water is extremely shallow. In contrast, nearly all of the dredged material placed in open water >1.5 m deep is reworked and either transported back into the channel or dispersed into the surrounding lagoon. A sediment flux analysis incorporating geotechnical properties demonstrated that erosion and not postemplacement compaction caused most sediment losses from the placement areas. Comparing sediment properties in the placement areas and natural lagoon indicated that the remaining dredged material is mostly a residual of initial channel construction. Experimental containment designs (shallow subaqueous mound, submerged levee, and emergent levee) constructed in high-maintenance areas to reduce reworking did not retain large volumes of dredged material. The emergent levee provided the greatest retention potential approximately 2 years after construction.

  2. High-Performance Wireless Internet Connection to Mount Laguna Observatory

    NASA Astrophysics Data System (ADS)

    Etzel, P. B.; Braun, H.-W.

    2000-12-01

    A 45 Mbit/sec full-duplex wireless Internet backbone is now under construction that will connect SDSU's Mount Laguna Observatory (MLO) to the San Diego Supercomputer Center (SDSC), which is located on the campus of UCSD. The SDSU campus is connected to the SDSC via Abilene/OC3 (Internet2) at 155 Mbit/sec. The MLO-SDSC backbone is part of the High-Performance Wireless Research and Education Network (HPWREN) project. Other scientific applications include earthquake monitoring from a remote array of automated seismic stations operated by researchers at the UCSD Institute for Geophysics and Planetary Physics, and environmental monitoring at Ecology field stations administered by SDSU. Educational initiatives include bringing the Internet to schools and educational centers at remote Indian reservations such as Pala and Rincon. HPWREN will allow SDSU astronomers and their collaborators to transmit CCD images to their home institutions while observations are being made. Archive retrieval of images from on-campus data bases, for comparison purposes, could easily be done. SDSU desires to build a modern, large telescope at MLO. HPWREN would support both robotic and remote observing capabilities for such a telescope. Astronomers could observe at their home institutions with multiple workstations to feed command and control instructions, data, and slow-scan video, which would give them the "feel" of being in a control room next to the telescope. HPWREN was funded by the NSF under grant ANI-0087344.

  3. Considerations for increasing unit 1 spent fuel pool capacity at the Laguna Verde station

    SciTech Connect

    Vera, A. )

    1992-01-01

    To increase the spent fuel storage capacity at the Laguna Verde Station in a safe and economical manner and assure a continuous operation of the first Mexican Nuclear Plant, Comision Federal de Electricidad (CFE), the Nation's Utility, seeked alternatives considering the overall world situation, the safety and licensing aspects, as well as the economics and the extent of the nuclear program of Mexico. This paper describes the alternatives considered, their evaluation and how the decision taken by CFE in this field, provides the Laguna Verde Station with a maximum of 37 years storage capacity plus full core reserve.

  4. Redhead duck behavior on lower Laguna Madre and adjacent ponds of southern Texas

    USGS Publications Warehouse

    Mitchell, C.A.; Custer, T.W.; Zwank, P.J.

    1992-01-01

    Behavior of redheads (Aythya americana) during winter was studied on the hypersaline lower Laguna Madre and adjacent freshwater to brackish water ponds of southern Texas. On Laguna Madre, feeding (46%) and sleeping (37%) were the most common behaviors. Redheads fed more during early morning (64%) than during the rest of the day (40%); feeding activity was negatively correlated with temperature. Redheads fed more often by dipping (58%) than by tipping (25%), diving (16%), or gleaning (0.1%). Water depth was least where they fed by dipping (16 cm), greatest where diving (75 cm), and intermediate where tipping (26 cm). Feeding sequences averaged 5.3 s for dipping, 8.1 s for tipping, and 19.2 s for diving. Redheads usually were present on freshwater to brackish water ponds adjacent to Laguna Madre only during daylight hours, and use of those areas declined as winter progressed. Sleeping (75%) was the most frequent behavior at ponds, followed by preening (10%), swimming (10%), and feeding (0.4%). Because redheads fed almost exclusively on shoalgrass while dipping and tipping in shallow water and shoalgrass meadows have declined in the lower Laguna Madre, proper management of the remaining shoalgrass habitat is necessary to ensure that this area remains the major wintering area for redheads.

  5. Vesicularity variation to pyroclasts from silicic eruptions at Laguna del Maule volcanic complex, Chile

    NASA Astrophysics Data System (ADS)

    Wright, H. M. N.; Fierstein, J.; Amigo, A.; Miranda, J.

    2014-12-01

    Crystal-poor rhyodacitic to rhyolitic volcanic eruptions at Laguna del Maule volcanic complex, Chile have produced an astonishing range of textural variation to pyroclasts. Here, we focus on eruptive deposits from two Quaternary eruptions from vents on the northwestern side of the Laguna del Maule basin: the rhyolite of Loma de Los Espejos and the rhyodacite of Laguna Sin Puerto. Clasts in the pyroclastic fall and pyroclastic flow deposits from the rhyolite of Loma de Los Espejos range from dense, non-vesicular (obsidian) to highly vesicular, frothy (coarsely vesicular reticulite); where vesicularity varies from <1% to >90%. Bulk compositions range from 75.6-76.7 wt.% SiO2. The highest vesicularity clasts are found in early fall deposits and widely dispersed pyroclastic flow deposits; the frothy carapace to lava flows is similarly highly vesicular. Pyroclastic deposits also contain tube pumice, and macroscopically folded, finely vesicular, breadcrusted, and heterogeneously vesiculated textures. We speculate that preservation of the highest vesicularities requires relatively low decompression rates or open system degassing such that relaxation times were sufficient to allow extensive vesiculation. Such an inference is in apparent contradiction to documentation of Plinian dispersal to the eruption. Clasts in the pyroclastic fall deposit of the rhyodacite (68-72 wt.% SiO2) of Laguna Sin Puerto are finely vesicular, with vesicularity modes at ~50% and ~68% corresponding to gray and white pumice colors, respectively. Some clasts are banded in color (and vesicularity). All clasts were fragmented into highly angular particles, with subplanar to slightly concave exterior surfaces (average Wadell Roundness of clast margins between 0.32 and 0.39), indicating brittle fragmentation. In contrast to Loma de Los Espejos, high bubble number densities to Laguna Sin Puerto rhyodacite imply high decompression rates.

  6. Migration chronology and distribution of redheads on the lower Laguna Madre, Texas

    USGS Publications Warehouse

    Custer, Christine M.; Custer, T.W.; Zwank, P.J.

    1997-01-01

    An estimated 80% of redheads (Aythya americana) winter on the Laguna Madre of southern Texas and Mexico. Because there have been profound changes in the Laguna Madre over the past three decades and the area is facing increasing industrial and recreational development, we studied the winter distribution and habitat requirements of redheads during two winters (1987-1988 and 1988-1989) on the Lower Laguna Madre, Texas to provide information that could be used to understand, identify, and protect wintering redhead habitat. Redheads began arriving on the Lower Laguna Madre during early October in 1987 and 1988, and continued to arrive through November. Redhead migration was closely associated with passing weather fronts. Redheads arrived on the day a front arrived and during the following two days; no migrants were observed arriving the day before a weather front arrived. Flock size of arriving redheads was 26.4 ± 0.6 birds and did not differ among days or by time of day (morning midday, or afternoon). Number of flocks arriving per 0.5 h interval (arrival rate) was greater during afternoon (21.7 ± 0.6) than during morning (4.3 ± 1.2) or midday (1.5 ± 0.4) on the day of frontal passage and during the first day after frontal passage. Upon arrival, redhead flocks congregated in the central portion of the Lower Laguna Madre. They continued to use the central portion throughout the winter, but gradually spread to the northern and southern ends of the lagoon. Seventy-one percent of the area used by flocks was vegetated with shoalgrass (Halodule wrightii) although shoalgrass covered only 32% of the lagoon. Flock movements seemed to be related to tide level; redheads moved to remain in water 12-30 cm deep. These data can be used by the environmental community to identify and protect this unique and indispensable habitat for wintering redheads.

  7. 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.

  8. 3D gravity inversion and thermodynamic modelling reveal properties of shallow silicic magma reservoir beneath Laguna del Maule, Chile

    NASA Astrophysics Data System (ADS)

    Miller, Craig A.; Williams-Jones, Glyn; Fournier, Dominique; Witter, Jeff

    2017-02-01

    Active, large volume, silicic magma systems are potentially the most hazardous form of volcanism on Earth. Knowledge of the location, size, and physical properties of silicic magma reservoirs, is therefore important for providing context in which to accurately interpret monitoring data and make informed hazard assessments. Accordingly, we present the first geophysical image of the Laguna del Maule volcanic field magmatic system, using a novel 3D inversion of gravity data constrained by thermodynamic modelling. The joint analysis of gravity and thermodynamic data allows for a rich interpretation of the magma system, and highlights the importance of considering the full thermodynamic effects on melt density, when interpreting gravity models of active magmatic systems. We image a 30 km3, low density, volatile rich magma reservoir, at around 2 km depth, containing at least 85% melt, hosted within a broader 115 km3 body interpreted as wholly or partially crystallised (>70% crystal) cumulate mush. Our model suggests a magmatic system with shallow, crystal poor magma, overlying deeper, crystal rich magma. Even though a large density contrast (-600 kg/m3) with the surrounding crust exists, the lithostatic load is 50% greater than the magma buoyancy force, suggesting buoyancy alone is insufficient to trigger an eruption. The reservoir is adjacent to the inferred extension of the Troncoso fault and overlies the location of an intruding sill, driving present day deformation. The reservoir is in close proximity to the 2.0 km3 Nieblas (rln) eruption at 2-3 ka, which we calculate tapped approximately 7% of the magma reservoir. However, we suggest that the present day magma system is not large enough to have fed all post-glacial eruptions, and that the location, or size of the system may have migrated or varied over time, with each eruption tapping only a small aliquot of the available magma. The presence of a shallow reservoir of volatile rich, near liquidus magma, in close

  9. Trace elements and organochlorines in the shoalgrass community of the lower Laguna Madre, Texas.

    PubMed

    Custer, T W; Mitchell, C A

    1993-05-01

    Our objectives were to measure concentrations of seven trace elements and 14 organochlorine compounds in sediment and biota of the shoalgrass (Halodule wrightii) community of the lower Laguna Madre of south Texas and to determine whether chemicals associated with agriculture (e.g. mercury, arsenic, selenium, organochlorine pesticides) were highest near agricultural drainages. Arsenic, mercury, selenium, lead, cadmium, and organochlorines were generally at background concentrations throughout the lower Laguna Madre. Nickel and chromium concentrations were exceptionally high in shrimp and pinfish (Lagodon rhomboides), which is difficult to explain because of no known anthropogenic sources for these trace elements. For sediment and blue crabs (Callinectes sapidus), mercury was highest near agricultural drainages. Also, DDE was more frequently detected in blue crabs near agricultural drainages than farther away. In contrast, selenium concentrations did not differ among collecting sites and arsenic concentrations were lowest in shoalgrass, blue crabs, and brown shrimp (Penaeus aztecus) near agricultural drainages.

  10. The microbial community at Laguna Figueroa, Baja California Mexico - From miles to microns

    NASA Technical Reports Server (NTRS)

    Stolz, J. F.

    1985-01-01

    The changes in the composition of the stratified microbial community in the sediments at Laguna Figeroa following floods are studied. The laguna which is located on the Pacific coast of the Baja California peninsula 200 km south of the Mexican-U.S. border is comprised of an evaporite flat and a salt marsh. Data collected from 1979-1983 using Landsat imagery, Skylab photographs, and light and transmission electron microscopy are presented. The flood conditions, which included 1-3 m of meteoric water covering the area and a remanent of 5-10 cm of siliciclastic and clay sediment, are described. The composition of the community prior to the flooding consisted of Microcoleus, Phormidium sp., a coccoid cynanobacteria, Phloroflexus, Ectothiorhodospira, Chloroflexus, Thiocapsa sp., and Chromatium. Following the floods Thiocapsa, Chromatium, Oscillatora sp., Spirulina sp., and Microcoleus are observed in the sediments.

  11. Trace elements and organochlorines in the shoalgrass community of the lower Laguna Madre Texas

    USGS Publications Warehouse

    Custer, T.W.; Mitchell, C.A.

    1993-01-01

    Our objectives were to measure concentrations of seven trace elements and 14 organochlorine compounds in sediment and biota of the shoalgrass (Halodule wrightii) community of the lower Laguna Madre of south Texas [USA] and to determine whether chemicals associated with agriculture (e.g. mercury, arsenic, selenium, organochlorine pesticides) were highest near agricultural drainage. Arsenic, mercury, selenium, lead, cadmium, and organochlorines were generally at background concentrations throughout the lower Laguna Madre. Nickel and chromium concentrations were exceptionally high in shrimp and pinfish (Lagodon rhomboides), which is difficult to explain because of no known anthropogenic sources for these trace elements. For sediment and blue crabs (Callinectes sapidus), mercury was highest near agricultural drainages. Also, DDE was more frequently detected in blue crabs near agricultural drainages than farther away. In contrast, selenium concentrations did not differ among collecting sites and arsenic concentrations were lowest n shoalgrass, blue crabs, and brown shrimp (Penaeus aztecus) near agricultural drainages.

  12. Hydrocarbon concentrations in sediments and clams (Rangia cuneata) in Laguna de Pom, Mexico

    SciTech Connect

    Alvarez-Legorreta, T.; Gold-Bouchot, G.; Zapata-Perez, O.

    1994-01-01

    Laguna de Pom is a coastal lagoon within the Laguna de Terminos system in southern Gulf of Mexico. It belongs to the Grijalva-Usumacinta basin, and is located between 18{degrees} 33{prime} and 18{degrees} 38{prime} north latitude and 92{degrees} 01{prime} and 92{degrees} 14{prime} west longitude, in the Coastal Plain physiographic Province of the Gulf. It is ellipsoidal and approximately 10 km long, with a surface area of 5,200 ha and a mean depth of 1.5 m. Water salinity and temperature ranges are 0 to 13 {per_thousand} and 25{degrees} to 31{degrees}C, respectively. Benthic macrofauna is dominated by bivalves such as the clams Rangia cuneata, R. flexuosa, and Polymesoda carolineana. These clams provide the basis of an artisanal fishery, which is the main economic activity in the region. The presence of several oil-processing facilities around the lagoon is very conspicuous, which together with decreasing yields has created social conflicts, with the fishermen blaming the mexican state oil company (PEMEX) for the decrease in the clam population. This work aims to determine if the concentration of hydrocarbons in the clams (R. cuneata) and sediments of Laguna de Pom are responsible for the declining clam fishery. 11 refs., 4 figs., 2 tabs.

  13. 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

  14. The San Andreas Fault

    USGS Publications Warehouse

    Schulz, Sandra S.; Wallace, Robert E.

    1993-01-01

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

  15. Fault-Tree Compiler

    NASA Technical Reports Server (NTRS)

    Butler, Ricky W.; Boerschlein, David P.

    1993-01-01

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

  16. Trishear for curved faults

    NASA Astrophysics Data System (ADS)

    Brandenburg, J. P.

    2013-08-01

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

  17. 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.

  18. 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.

  19. Niebla ceruchis from Laguna Figueroa: dimorphic spore morphology and secondary compounds localized in pycnidia and apothecia

    NASA Technical Reports Server (NTRS)

    Enzien, M.; Margulis, L.

    1988-01-01

    During and after the floods of 1979-80 Niebla ceruchis growing epiphytically on Lycium brevipes was one of the dominant aspects of the vegetation in the coastal dunal complex bordering the microbial mats at Laguna Figueroa, Baja California Norte, Mexico. The lichen on denuded branches of Lycium was far more extensively distributed than Lycium lacking lichen. Unusual traits of this Niebla ceruchis strain, namely localization of lichen compounds in the mycobiont reproductive structures (pycnidia and apothecia) and simultaneous presence of bilocular and quadrilocular ascospores, are reported. The abundance of this coastal lichen cover at the microbial mat site has persisted through April 1988.

  20. Rock Magnetic Properties of Laguna Carmen (Tierra del Fuego, Argentina): Implications for Paleomagnetic Reconstruction

    NASA Astrophysics Data System (ADS)

    Gogorza, C. G.; Orgeira, M. J.; Ponce, F.; Fernández, M.; Laprida, C.; Coronato, A.

    2013-05-01

    We report preliminary results obtained from a multi-proxy analysis including paleomagnetic and rock-magnetic studies of two sediment cores of Laguna Carmen (53°40'60" S 68°19'0" W, ~83m asl) in the semiarid steppe in northern Tierra del Fuego island, Southernmost Patagonia, Argentina. Two short cores (115 cm) were sampled using a Livingstone piston corer during the 2011 southern fall. Sediments are massive green clays (115 to 70 cm depth) with irregularly spaced thin sandy strata and lens. Massive yellow clay with thin sandy strata continues up to 30 cm depth; from here up to 10 cm yellow massive clays domain. The topmost 10 cm are mixed yellow and green clays with fine sand. Measurements of intensity and directions of Natural Remanent Magnetization (NRM), magnetic susceptibility, isothermal remanent magnetization, saturation isothermal remanent magnetization (SIRM), back field and anhysteretic remanent magnetization at 100 mT (ARM100mT) were performed and several associated parameters calculated (ARM100mT/k and SIRM/ ARM100mT). Also, as a first estimate of relative magnetic grain-size variations, the median destructive field of the NRM (MDFNRM), was determined. Additionally, we present results of magnetic parameters measured with vibrating sample magnetometer (VSM). The stability of the NRM was analyzed by alternating field demagnetization. The magnetic properties have shown variable values, showing changes in both grain size and concentration of magnetic minerals. It was found that the main carrier of remanence is magnetite with the presence of hematite in very low percentages. This is the first paleomagnetic study performed in lakes located in the northern, semiarid fuegian steppe, where humid-dry cycles have been interpreted all along the Holocene from an aeolian paleosoil sequence (Orgeira et el, 2012). Comparison between paleomagnetic records of Laguna Carmen and results obtained in earlier studies carried out at Laguna Potrok Aike (Gogorza et al., 2012

  1. 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.

  2. Remote sensing analysis for fault-zones detection in the Central Andean Plateau (Catamarca, Argentina)

    NASA Astrophysics Data System (ADS)

    Traforti, Anna; Massironi, Matteo; Zampieri, Dario; Carli, Cristian

    2015-04-01

    Remote sensing techniques have been extensively used to detect the structural framework of investigated areas, which includes lineaments, fault zones and fracture patterns. The identification of these features is fundamental in exploration geology, as it allows the definition of suitable sites for the exploitation of different resources (e.g. ore mineral, hydrocarbon, geothermal energy and groundwater). Remote sensing techniques, typically adopted in fault identification, have been applied to assess the geological and structural framework of the Laguna Blanca area (26°35'S-66°49'W). This area represents a sector of the south-central Andes localized in the Argentina region of Catamarca, along the south-eastern margin of the Puna plateau. The study area is characterized by a Precambrian low-grade metamorphic basement intruded by Ordovician granitoids. These rocks are unconformably covered by a volcano-sedimentary sequence of Miocene age, followed by volcanic and volcaniclastic rocks of Upper Miocene to Plio-Pleistocene age. All these units are cut by two systems of major faults, locally characterized by 15-20 m wide damage zones. The detection of main tectonic lineaments in the study area was firstly carried out by classical procedures: image sharpening of Landsat 7 ETM+ images, directional filters applied to ASTER images, medium resolution Digital Elevation Models analysis (SRTM and ASTER GDEM) and hill shades interpretation. In addition, a new approach in fault zone identification, based on multispectral satellite images classification, has been tested in the Laguna Blanca area and in other sectors of south-central Andes. In this perspective, several prominent fault zones affecting basement and granitoid rocks have been sampled. The collected fault gouge samples have been analyzed with a Field-Pro spectrophotometer mounted on a goniometer. We acquired bidirectional reflectance spectra, from 0.35μm to 2.5μm with 1nm spectral sampling, of the sampled fault rocks

  3. Seagrasses, Dredging and Light in Laguna Madre, Texas, U.S.A.

    NASA Astrophysics Data System (ADS)

    Onuf, Christopher P.

    1994-07-01

    Light reduction resulting from maintenance dredging was the suspected cause of large-scale loss of seagrass cover in deep parts of Laguna Madre between surveys conducted in 1965 and 1974. Additional changes to 1988, together with an analysis of dredging frequency and intensity for different parts of the laguna, were consistent with this interpretation. Intensive monitoring of the underwater light regime and compilation of detailed environmental data for 3 months before and 15 months after a dredging project in 1988 revealed reduced light attributable to dredging in four of eight subdivisions of the study area, including the most extensive seagrass meadow in the study area. Dredging effects were strongest close to disposal areas used during this project but still were detectable on transects >1·2 km from the nearest dredge disposal area. In the subdivision of the study area where most of the dredge disposal occurred, light attenuation was increased throughout the 15 months of observation after dredging. In the seagrass meadow and the transition zone at the outer edge of the meadow, effects were evident up to 10 months after dredging. Resuspension and dispersion events caused by wind-generated waves are responsible for the propagation of dredge-related turbidity over space and time in this system.

  4. Organochlorines and trace elements in four colonial waterbird species nesting in the lower Laguna Madre, Texas.

    PubMed

    Mora, M A

    1996-11-01

    Eggs from four aquatic bird species nesting on the National Audubon Sanctuary Islands of the lower Laguna Madre were collected during 1993 and 1994 to determine concentrations of organochlorine compounds and trace metals and to evaluate their possible detrimental effects on birds nesting in this aquatic ecosystem. The only chlorinated hydrocarbons found above detection limits were p,p'-DDE (DDE), p,p'-DDT (DDT), HCB, HCH, chlordane, and polychlorinated biphenyls (PCBs). Median DDE and PCB levels in eggs of four species were below 1 microgram/g ww. Concentrations of DDE were much greater (6-70 fold) than the concentrations of other chlorinated pesticides which were present at or near detection limits. One egg from a snowy egret contained 9.65 micrograms/g DDE, 0.056 microgram/g DDD, and 1.75 micrograms/g DDT. Ten heavy metals and trace elements (Hg, Se, B, Cr, Cu, Fe, Mg, Mn, Sr, and Zn) were detected in 90% of the samples but at levels that were not of concern. In 1993-1994, concentrations of DDE in eggs of aquatic birds of the lower Laguna Madre were much lower than levels detected in this area during the late 1970s and early 1980s. Concentrations of DDE, PCBs, and trace metals in eggs detected in this study could not be associated with deformities or other detrimental effects on birds.

  5. Water resources on the Pueblo of Laguna, west-central New Mexico

    USGS Publications Warehouse

    Risser, D.W.; Lyford, F.P.

    1983-01-01

    This study evaluates the quality and quantity of water available on the Pueblo of Laguna, New Mexico. Groundwater for public supply occurs in the valley fill along the Rio San Jose, in the Paguate and Encinal areas, and possibly in the northern part of the Sedillo Grant. The valley fill in the Rio San Jose will supply 50 to 450 gallons per minute of potable water to properly constructed wells. In the alluvium along Rio Paguate, additional development of as much as 250 gallons per minute is possible. Groundwater for irrigation is restricted by available yields and quality to the valley fill along the Rio San Jose and possibly the western part of the Major 's Ranch area. In the Rio San Jose valley yields of 50 to 450 gallons per minute of water containing 500 to 3,000 milligrams per liter are possible. Digital-model simulations of the valley-fill aquifer west of the Village of Laguna show a potential salvage of as much as 900 acre-feet per year of evapotranspiration losses if water levels are lowered. Model studies also indicate that the winter flow of the Rio San Jose could be used to recharge groundwater stored in the valley. (USGS)

  6. Water-quality reconnaissance of Laguna Tortuguero, Vega Baja, Puerto Rico, March 1999-May 2000

    USGS Publications Warehouse

    Soler-Lopez, Luis; Guzman-Rios, Senen; Conde-Costas, Carlos

    2006-01-01

    The Laguna Tortuguero, a slightly saline to freshwater lagoon in north-central Puerto Rico, has a surface area of about 220 hectares and a mean depth of about 1.2 meters. As part of a water-quality reconnaissance, water samples were collected at about monthly and near bi-monthly intervals from March 1999 to May 2000 at four sites: three stations inside the lagoon and one station at the artificial outlet channel dredged in 1940, which connects the lagoon with the Atlantic Ocean. Physical characteristics that were determined from these water samples were pH, temperature, specific conductance, dissolved oxygen, dissolved oxygen saturation, and discharge at the outlet canal. Other water-quality constituents also were determined, including nitrogen and phosphorus species, organic carbon, chlorophyll a and b, plankton biomass, hardness, alkalinity as calcium carbonate, and major ions. Additionally, a diel study was conducted at three stations in the lagoon to obtain data on the diurnal variation of temperature, specific conductance, dissolved oxygen, and dissolved oxygen saturation. The data analysis indicates the water quality of Laguna Tortuguero complies with the Puerto Rico Environmental Quality Board standards and regulations.

  7. Origin and evolution of the Laguna Potrok Aike maar (Patagonia, Argentina)

    NASA Astrophysics Data System (ADS)

    Gebhardt, A. C.; de Batist, M.; Niessen, F.; Anselmetti, F. S.; Ariztegui, D.; Ohlendorf, C.; Zolitschka, B.

    2009-04-01

    Laguna Potrok Aike, a maar lake in southern-most Patagonia, is located at about 110 m a.s.l. in the Pliocene to late Quaternary Pali Aike Volcanic Field (Santa Cruz, southern Patagonia, Argentina) at about 52°S and 70°W, some 20 km north of the Strait of Magellan and approximately 90 km west of the city of Rio Gallegos. The lake is almost circular and bowl-shaped with a 100 m deep, flat plain in its central part and an approximate diameter of 3.5 km. Steep slopes separate the central plain from the lake shoulder at about 35 m water depth. At present, strong winds permanently mix the entire water column. The closed lake basin contains a sub saline water body and has only episodic inflows with the most important episodic tributary situated on the western shore. Discharge is restricted to major snowmelt events. Laguna Potrok Aike is presently located at the boundary between the Southern Hemispheric Westerlies and the Antarctic Polar Front. The sedimentary regime is thus influenced by climatic and hydrologic conditions related to the Antarctic Circumpolar Current, the Southern Hemispheric Westerlies and sporadic outbreaks of Antarctic polar air masses. Previous studies demonstrated that closed lakes in southern South America are sensitive to variations in the evaporation/precipitation ratio and have experienced drastic lake level changes in the past causing for example the desiccation of the 75 m deep Lago Cardiel during the Late Glacial. Multiproxy environmental reconstruction of the last 16 ka documents that Laguna Potrok Aike is highly sensitive to climate change. Based on an Ar/Ar age determination, the phreatomagmatic tephra that is assumed to relate to the Potrok Aike maar eruption was formed around 770 ka. Thus Laguna Potrok Aike sediments contain almost 0.8 million years of climate history spanning several past glacial-interglacial cycles making it a unique archive for non-tropical and non-polar regions of the Southern Hemisphere. In particular, variations of

  8. A 20,000-year record of environmental change from Laguna Kollpa Kkota, Bolivia

    SciTech Connect

    Seltzer, G.O. . Mendenhall Lab.); Abbott, M.B. )

    1992-01-01

    Most records of paleoclimate in the Bolivian Andes date from the last glacial-to-interglacial transition. However, Laguna Kollpa Kkota and other lakes like it, formed more than 20,000 yr BP when glaciers retreated and moraines dammed the drainage of the valleys they are located in. These lakes were protected from subsequent periods of glaciation because the headwalls of these valleys are below the level of the late-Pleistocene glacial equilibrium-line altitude. The chemical, mineral, and microfossil stratigraphies of these glacial lakes provide continuous records of environmental change for the last 20,000 years that can be used to address several problems in paleoclimate specific to tropical-subtropical latitudes. Preliminary results from Laguna Kollpa Kkota indicate that glacial equilibrium-line altitudes were never depressed more than 600 m during the last 20,000 years, suggesting that temperatures were reduced only a few-degrees celsius over this time period. Sedimentation rates and the organic carbon stratigraphy of cores reflect an increase in moisture in the late Pleistocene just prior to the transition to a warmer and drier Holocene. The pollen and diatom concentrations in the sediments are sufficient to permit the high resolution analyses needed to address whether or not there were climatic reversals during the glacial-to-interglacial transition.

  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. Winter distributions of North American Plovers in the Laguna Madre regions of Tamaulipas, Mexico and Texas, USA

    USGS Publications Warehouse

    Mabee, Todd J.; Plissner, Jonathan H.; Haig, Susan M.; Goossen, J.P.

    2001-01-01

    To determine the distribution and abundance of wintering plovers in the Laguna Madre of Texas and Tamaulipas, surveys were conducted in December 1997 and February 1998, along a 160 km stretch of barrier islands in Mexico and- 40 km of shoreline on South Padre Island, Texas. Altogether, 5,673 individuals, representing six plover species, were recorded during the surveys. Black-bellied Plovers Pluvialis squatarola were the most numerous (3 ,013 individuals) representing 53% of the total number of plovers observed. Numbers of Piping Charadriusm elodu, Snowy C . alexandrinus, Semipalmated C. semipalmatus and Wilson's Plovers C. wilsonia were 739, 1,345, 561, and 13 birds, respectively. Most individuals (97%) of all species except Wilson's Plovers were observed on bayside flats of the barrier islands. Similar numbers of Piping Plovers were recorded at South Padre Island, Texas, and in the Laguna Madre de Tamaulipas. Over 85% of the individuals of each of the other species were found in the more extensively surveyed Mexico portion of Laguna Madre. In Tamaulipas, most plover species were observed more often on algal flats than any other substrate. These results provide evidence of the value of these systems as wintering areas for plover species and indicate the need for more extensive survey efforts to determine temporal and spatial variation in the distribution of these species within the Laguna ecosystem.

  11. 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.

  12. Characterization of leaky faults

    SciTech Connect

    Shan, Chao

    1990-05-01

    Leaky faults provide a flow path for fluids to move underground. It is very important to characterize such faults in various engineering projects. The purpose of this work is to develop mathematical solutions for this characterization. The flow of water in an aquifer system and the flow of air in the unsaturated fault-rock system were studied. If the leaky fault cuts through two aquifers, characterization of the fault can be achieved by pumping water from one of the aquifers, which are assumed to be horizontal and of uniform thickness. Analytical solutions have been developed for two cases of either a negligibly small or a significantly large drawdown in the unpumped aquifer. Some practical methods for using these solutions are presented. 45 refs., 72 figs., 11 tabs.

  13. 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.

  14. 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.

  15. Trace metal partitioning in Thalassia testudinum and sediments in the Lower Laguna Madre, Texas.

    PubMed

    Whelan, Thomas; Espinoza, Jorge; Villarreal, Xiomara; Cottagoma, Maria

    2005-01-01

    Seagrass communities dominate the Laguna Madre, which accounts for 25% of the coastal region of Texas. Seagrasses are essential to the health of the Laguna Madre (LM) and have experienced an overall decline in coverage in the Lower Laguna Madre (LLM) since 1967. Little is known on the existing environmental status of the LLM. This study focuses on the trace metal chemistry of four micronutrient metals, Fe, Mn, Cu, and Zn, and two non-essential metals, Pb and As, in the globally important seagrass Thalassia testudinum. Seasonal trends show that concentrations of most essential trace metals increase in the tissue during the summer months. With the exception of (1) Cu in the vertical shoot and root, and (2) Mn in the roots, no significant positive correlation exists between the rhizosphere sediment and T. testudinum tissue. Iron indicates a negative correlation between the morphological units and the rhizosphere sediments. No other significant relationship was found between the sediments and the T. testudinum tissue. Mn was enriched up to 10-fold in the leaf tissue relative to the other morphological units and also enriched relative to the rhizosphere sediments. Both Cu and Mn appear to be enriched in leaf tissue compared to other morphological units and also enriched relative to the Cu and Mn in the rhizoshpere sediments. Sediments cores taken in barren areas were slightly elevated in Zn relative to the rhizosphere sediments, whereas no other metals showed statistical differences between barren sediment cores and rhizosphere sediments. However, no correlation was measured in T. testudinum tissue and Zn in rhizosphere sediments. Previous studies suggested that Fe/Mn ratios could indicate differences between seagrass environments. Our results indicate that there is an influence from the Rio Grande in the Fe/Mn signature in sediments, and that ratio is not reflected in the T. testudinum tissue. The results from this study show that the LLM contains trace metal

  16. Rough faults, distributed weakening, and off-fault deformation

    NASA Astrophysics Data System (ADS)

    Griffith, W. Ashley; Nielsen, Stefan; di Toro, Giulio; Smith, Steven A. F.

    2010-08-01

    We report systematic spatial variations in fault rocks along nonplanar strike-slip faults cross-cutting the Lake Edison Granodiorite, Sierra Nevada, California (Sierran wavy fault) and Lobbia outcrops of the Adamello Batholith in the Italian Alps (Lobbia wavy fault). In the case of the Sierran fault, pseudotachylyte formed at contractional fault bends, where it is found as thin (1-2 mm) fault-parallel veins. Epidote and chlorite developed in the same seismic context as the pseudotachylyte and are especially abundant in extensional fault bends. We argue that the presence of fluids, as illustrated by this example, does not necessarily preclude the development of frictional melt. In the case of the Lobbia fault, pseudotachylyte thickness varies along the length of the fault, but the pseudotachylyte veins thicken and pool in extensional bends. We conduct a quantitative analysis of fault roughness, microcrack distribution, stress, and friction along the Lobbia fault. Numerical modeling results show that opening in extensional bends and localized thermal weakening in contractional bends counteract resistance encountered by fault waviness, resulting in an overall weaker fault than suggested by the corresponding static friction coefficient. The models also predict static stress redistribution around bends in the faults which is consistent with distribution of microcracks, indicating significant elastic and inelastic strain energy is dissipated into the wall rocks due to nonplanar fault geometry. Together these observations suggest that damage and energy dissipation occurs along the entire nonplanar fault during slip, rather than being confined to the region close to the dynamically propagating crack tip.

  17. Water quality mapping of Laguna de Bay and its watershed, Philippines

    NASA Astrophysics Data System (ADS)

    Saito, S.; Nakano, T.; Shin, K.; Maruyama, S.; Miyakawa, C.; Yaota, K.; Kada, R.

    2011-12-01

    Laguna de Bay (or Laguna Lake) is the largest lake in the Philippines, with a surface area of 900 km2 and its watershed area of 2920 km2 (Santos-Borja, 2005). It is located on the southwest part of the Luzon Island and its watershed contains 5 provinces, 49 municipalities and 12 cities, including parts of Metropolitan Manila. The water quality in Laguna de Bay has significantly deteriorated due to pollution from soil erosion, effluents from chemical industries, and household discharges. In this study, we performed multiple element analysis of water samples in the lake and its watersheds for chemical mapping, which allows us to evaluate the regional distribution of elements including toxic heavy metals such as Cd, Pb and As. We collected water samples from 24 locations in Laguna de Bay and 160 locations from rivers in the watersheds. The sampling sites of river are mainly downstreams around the lake, which covers from urbanized areas to rural areas. We also collected well water samples from 17 locations, spring water samples from 10 locations, and tap water samples from 21 locations in order to compare their data with the river and lake samples and to assess the quality of household use waters. The samples were collected in dry season of the study area (March 13 - 17 and May 2 - 9, 2011). The analysis was performed at the Research Institute for Humanity and Nature (RIHN), Japan. The concentrations of the major components (Cl, NO3, SO4, Ca, Mg, Na, and K) dissolved in the samples were determined with ion chromatograph (Dionex Corporation ICS-3000). We also analyzed major and trace elements (Li, B, Na, Mg, Al, Si, P, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn Ga, Ge, As, Se, Rb, Sr, Y, Zr, Mo, Ag, Cd, Sn, Sb, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, W, Pb and U) with inductively coupled plasma-mass spectrometry (ICP-MS, Agilent Technologies 7500cx). The element concentrations of rivers are characterized by remarkable regional variations. For

  18. Late Pleistocene-early Holocene karst features, Laguna Madre, south Texas: A record of climate change

    SciTech Connect

    Prouty, J.S.

    1996-09-01

    A Pleistocene coquina bordering Laguna Madre, south Texas, contains well-developed late Pleistocene-early Holocene karst features (solution pipes and caliche crusts) unknown elsewhere from coastal Texas. The coquina accumulated in a localized zone of converging longshore Gulf currents along a Gulf beach. The crusts yield {sup 14}C dates of 16,660 to 7630 B.P., with dates of individual crust horizons becoming younger upwards. The karst features provide evidence of regional late Pleistocene-early Holocene climate changes. Following the latest Wisconsinan lowstand 18,000 B.P. the regional climate was more humid and promoted karst weathering. Partial dissolution and reprecipitation of the coquina formed initial caliche crust horizons; the crust later thickened through accretion of additional carbonate laminae. With the commencement of the Holocene approximately 11,000 B.P. the regional climate became more arid. This inhibited karstification of the coquina, and caliche crust formation finally ceased about 7000 B.P.

  19. Response of shoal grass, Halodule wrightii, to extreme winter conditions in the Lower Laguna Madre, Texas

    USGS Publications Warehouse

    Hicks, D.W.; Onuf, C.P.; Tunnell, J.W.

    1998-01-01

    Effects of a severe freeze on the shoal grass, Halodule wrightii, were documented through analysis of temporal and spatial trends in below-ground biomass. The coincidence of the second lowest temperature (-10.6??C) in 107 years of record, 56 consecutive hours below freezing, high winds and extremely low water levels exposed the Laguna Madre, TX, to the most severe cold stress in over a century. H. wrightii tolerated this extreme freeze event. Annual pre- and post-freeze surveys indicated that below-ground biomass estimated from volume was Unaffected by the freeze event. Nor was there any post-freeze change in biomass among intertidal sites directly exposed to freezing air temperatures relative to subtidal sites which remained submerged during the freezing period.

  20. Fault Management Metrics

    NASA Technical Reports Server (NTRS)

    Johnson, Stephen B.; Ghoshal, Sudipto; Haste, Deepak; Moore, Craig

    2017-01-01

    This paper describes the theory and considerations in the application of metrics to measure the effectiveness of fault management. Fault management refers here to the operational aspect of system health management, and as such is considered as a meta-control loop that operates to preserve or maximize the system's ability to achieve its goals in the face of current or prospective failure. As a suite of control loops, the metrics to estimate and measure the effectiveness of fault management are similar to those of classical control loops in being divided into two major classes: state estimation, and state control. State estimation metrics can be classified into lower-level subdivisions for detection coverage, detection effectiveness, fault isolation and fault identification (diagnostics), and failure prognosis. State control metrics can be classified into response determination effectiveness and response effectiveness. These metrics are applied to each and every fault management control loop in the system, for each failure to which they apply, and probabilistically summed to determine the effectiveness of these fault management control loops to preserve the relevant system goals that they are intended to protect.

  1. Looking for Biosignatures in Carbonate Microbialites from the Laguna Negra, Argentinian Andes

    NASA Astrophysics Data System (ADS)

    Boidi, F. J.; Gomez, F. J.; Fike, D. A.; Bradley, A. S.; Farías, M. E.; Beeler, S.

    2015-12-01

    The distinction between biotic and abiotic control on microbialites formation and its signatures is relevant since stromatolites are considered the oldest evidence for life on Earth and a target for astrobiological research. The Laguna Negra is a shallow hypersaline lake placed at the Andes, Northwest Argentina, where carbonate microbialites and microbial mats develop. It is a unique system where microbial influence on carbonate precipitation and potential preserved biosignatures in the microbialites can be studied. Here we compare three distinct microbialites systems: carbonate laminar crusts with no visible microbial mats, stromatolites and dm-size oncoids, both related with different microbial mats. Our goal is to unravel the biotic controls on their formation, and the biosignatures there recorded. Laminar crusts are composed of stacked regular and isopachous carbonate lamina. Oncoids laminae are typically characterized by irregular hybrid micro-textures, composed of alternating micritic and botryoidal laminae, and the stromatolites are mostly composed by irregular micritic laminae. Sulfur isotopes of carbonate associated sulphate show similar values but they show differences in the pyrite sulfur isotopes suggesting differences in the fractionation degree, possibly related to sulphate reducing bacteria and variable sulphate reservoirs in the case of stromatolites and oncoids. δ13C fractionation between organic carbon and carbonates suggests photosynthesis, but other metabolisms cannot yet be discarded. 16S rDNA data of the microbial communities associated with the carbonate structures indicate the presence of these taxonomic groups and those that are known to influence carbonate precipitation, particularly in the stromatolites associated microbial community. Our data indicate significant differences between the three systems in terms of stable isotopes, textures and associated microbial diversity, suggesting a microbial control on stromatolites and oncoids

  2. 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.

  3. Fault detection and isolation

    NASA Technical Reports Server (NTRS)

    Bernath, Greg

    1993-01-01

    Erroneous measurements in multisensor navigation systems must be detected and isolated. A recursive estimator can find fast growing errors; a least squares batch estimator can find slow growing errors. This process is called fault detection. A protection radius can be calculated as a function of time for a given location. This protection radius can be used to guarantee the integrity of the navigation data. Fault isolation can be accomplished using either a snapshot method or by examining the history of the fault detection statistics.

  4. 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.

  5. Implementacion de modulos constructivistas que atiendan "misconceptions" y lagunas conceptuales en temas de la fisica en estudiantes universitarios

    NASA Astrophysics Data System (ADS)

    Santacruz Sarmiento, Neida M.

    Este estudio se enfoco en los "misconception" y lagunas conceptuales en temas fundamentales de Fisica como son Equilibrio Termodinamico y Estatica de fluidos. En primer lugar se trabajo con la identificacion de "misconceptions" y lagunas conceptuales y se analizo en detalle la forma en que los estudiantes construyen sus propias teorias de fenomenos relacionados con los temas. Debido a la complejidad en la que los estudiantes asimilan los conceptos fisicos, se utilizo el metodo de investigacion mixto de tipo secuencial explicativo en dos etapas, una cuantitativa y otra cualitativa. La primera etapa comprendio cuatro fases: (1) Aplicacion de una prueba diagnostica para identificar el conocimiento previo y lagunas conceptuales. (2) Identificacion de "misconceptions" y lagunas del concepto a partir del conocimiento previo. (3) Implementacion de la intervencion por medio de modulos en el topico de Equilibrio Termodinamico y Estatica de Fluidos. (4) Y la realizacion de la pos prueba para analizar el impacto y la efectividad de la intervencion constructivista. En la segunda etapa se utilizo el metodo de investigacion cualitativo, por medio de una entrevista semiestructurada que partio de la elaboracion de un mapa conceptual y se finalizo con un analisis de datos conjuntamente. El desarrollo de este estudio permitio encontrar "misconceptions" y lagunas conceptuales a partir del conocimiento previo de los estudiantes participantes en los temas trabajados, que fueron atendidos en el desarrollo de las distintas actividades inquisitivas que se presentaron en el modulo constructivista. Se encontro marcadas diferencias entre la pre y pos prueba en los temas, esto se debio al requerimiento de habilidades abstractas para el tema de Estatica de Fluidos y al desarrollo intuitivo para el tema de Equilibrio Termodinamico, teniendo mejores respuestas en el segundo. Los participantes demostraron una marcada evolucion y/o cambio en sus estructuras de pensamiento, las pruebas estadisticas

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  7. OpenStudio - Fault Modeling

    SciTech Connect

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

    2014-09-19

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

  8. 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

  9. A case of paleo-creep? Comparison of fault displacements in a trench with the corresponding earthquake record in lake sediments along the Polochic fault, Guatemala

    NASA Astrophysics Data System (ADS)

    Brocard, Gilles; Anselmetti, Flavio

    2014-05-01

    The Polochic and Motagua strike-slip faults in Guatemala accommodate the displacement (~2 cm/y) across the boundary between the Caribbean and North American plates. Both faults are expected to produce large destructive earthquakes such as the Mw 7.5 earthquake of 1976 on the Motagua fault. Former large earthquakes with magnitudes larger than Mw 7.0 are suggested from the areal extent of destructions to Precolombian Mayan cities and churches, and both the Motagua and Polochic fault have been suspected as the sources of these earthquakes. The available record, however, is surprisingly poor in large earthquakes, suggesting either that the record is sketchy or that such earthquakes are effectively infrequent. We investigated the activity of the Polochic fault by opening trenches along its major strand in Uspantán, Quiché, and Agua Blanca, Alta Verapaz. Recent displacements are evidenced in Agua Blanca, with soils less than 350 years old disrupted by the fault. We combined the study of the trenches with the study of sediment cores in Laguna Chichój, a lake located 4 km north of the Polochic fault. We had previously conducted an analysis of the sensitivity of the Chichój lake sediments to earthquakes in the 20th century. In the 20th centurey the earthquake record is well known, as well the locally felt intensity of these earthquakes. We found that for MMI intensities of VI and higher turbidites and slumps are produced in the lake. We used this calibration to study the earthquake record of the past 12 centuries and identified a cluster of earthquakes with MMI > VI between 830 and 1450 AD. The oldest seismite temporally matches widespread destructions in Mayan cities in 830 AD. Surprisingly, no earthquakes are recorded between 1450 and 1976 AD. Yet, the trench in Agua Blanca records substantial displacement of the Polochic fault over the period. It seems therefore that this ultimate displacement did not produce any substantial earthquake, and may correspond to a period

  10. Fault tolerant magnetic bearings

    SciTech Connect

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

    1999-07-01

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

  11. Pen Branch Fault Program

    SciTech Connect

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

    1990-09-28

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

  12. Triggered surface slips in southern California associated with the 2010 El Mayor-Cucapah, Baja California, Mexico, earthquake

    USGS Publications Warehouse

    Rymer, Michael J.; Treiman, Jerome A.; Kendrick, Katherine J.; Lienkaemper, James J.; Weldon, Ray J.; Bilham, Roger; Wei, Meng; Fielding, Eric J.; Hernandez, Janis L.; Olson, Brian P.E.; Irvine, Pamela J.; Knepprath, Nichole; Sickler, Robert R.; Tong, Xiaopeng; Siem, Martin E.

    2011-01-01

    Triggered slip in the Yuha Desert area occurred along more than two dozen faults, only some of which were recognized before the April 4, 2010, El Mayor-Cucapah earthquake. From east to northwest, slip occurred in seven general areas: (1) in the Northern Centinela Fault Zone (newly named), (2) along unnamed faults south of Pinto Wash, (3) along the Yuha Fault (newly named), (4) along both east and west branches of the Laguna Salada Fault, (5) along the Yuha Well Fault Zone (newly revised name) and related faults between it and the Yuha Fault, (6) along the Ocotillo Fault (newly named) and related faults to the north and south, and (7) along the southeasternmost section of the Elsinore Fault. Faults that slipped in the Yuha Desert area include northwest-trending right-lateral faults, northeast-trending left-lateral faults, and north-south faults, some of which had dominantly vertical offset. Triggered slip along the Ocotillo and Elsinore Faults appears to have occurred only in association with the June 14, 2010 (Mw5.7), aftershock. This aftershock also resulted in slip along other faults near the town of Ocotillo. Triggered offset on faults in the Yuha Desert area was mostly less than 20 mm, with three significant exceptions, including slip of about 50–60 mm on the Yuha Fault, 40 mm on a fault south of Pinto Wash, and about 85 mm on the Ocotillo Fault. All triggered slips in the Yuha Desert area occurred along preexisting faults, whether previously recognized or not.

  13. Geological setting and paleomagnetism of the Eocene red beds of Laguna Brava Formation (Quebrada Santo Domingo, northwestern Argentina)

    NASA Astrophysics Data System (ADS)

    Vizán, H.; Geuna, S.; Melchor, R.; Bellosi, E. S.; Lagorio, S. L.; Vásquez, C.; Japas, M. S.; Ré, G.; Do Campo, M.

    2013-01-01

    The red bed succession cropping out in the Quebrada Santo Domingo in northwestern Argentina had been for long considered as Upper Triassic-Lower Jurassic in age based on weak radiometric and paleontological evidence. Preliminary paleomagnetic data confirmed the age and opened questions about the nature of fossil footprints with avian features discovered in the section. Recently the stratigraphic scheme was reviewed with the identification of previously unrecognized discontinuities, and a radiometric dating obtained in a tuff, indicated an Eocene age for the Laguna Brava Formation and the fossil bird footprints, much younger than the previously assigned. We present a detailed paleomagnetic study interpreted within a regional tectonic and stratigraphic framework, looking for an explanation for the misinterpretation of the preliminary paleomagnetic data. The characteristic remanent magnetizations pass a tilt test and a reversal test. The main magnetic carrier is interpreted to be low Ti titanomagnetites and to a lesser extent hematite. The characteristic remanent magnetization would be essentially detrital. The obtained paleomagnetic pole (PP) for the Laguna Brava Formation has the following geographic coordinates and statistical parameters: N = 29, Lon. = 184.5° E, Lat. = 75.0° S, A95 = 5.6° and K = 23.7. When this PP is compared with another one with similar age obtained in an undeformed area, a declination anomaly is recognized. This anomaly can be interpreted as Laguna Brava Formation belonging to a structural block that rotated about 16° clockwise along a vertical axis after about 34 Ma. This block rotation is consistent with the regional tectonic framework, and would have caused the fortuitous coincidence of the PP with Early Jurassic poles. According to the interpreted magnetostratigraphic correlation, the Laguna Brava Formation would have been deposited during the Late Eocene with a mean sedimentation rate of about 1.4 cm per thousand years, probably in

  14. Set-up of a decision support system to support sustainable development of the Laguna de Bay, Philippines.

    PubMed

    Nauta, Tjitte A; Bongco, Alicia E; Santos-Borja, Adelina C

    2003-01-01

    Over recent decades, population expansion, deforestation, land conversion, urbanisation, intense fisheries and industrialisation have produced massive changes in the Laguna de Bay catchment, Philippines. The resulting problems include rapid siltation of the lake, eutrophication, inputs of toxics, flooding problems and loss of biodiversity. Rational and systematic resolution of conflicting water use and water allocation interests is now urgently needed in order to ensure sustainable use of the water resources. With respect to the competing and conflicting pressures on the water resources, the Laguna Lake Development Authority (LLDA) needs to achieve comprehensive management and development of the area. In view of these problems and needs, the Government of the Netherlands was funding a two-year project entitled 'Sustainable Development of the Laguna de Bay Environment'.A comprehensive tool has been developed to support decision-making at catchment level. This consists of an ArcView GIS-database linked to a state-of-the-art modelling suite, including hydrological and waste load models for the catchment area and a three-dimensional hydrodynamic and water quality model (Delft3D) linked to a habitat evaluation module for the lake. In addition, MS Office based tools to support a stakeholder analysis and financial and economic assessments have been developed. The project also focused on technical studies relating to dredging, drinking water supply and infrastructure works. These aimed to produce technically and economically feasible solutions to water quantity and quality problems. The paper also presents the findings of a study on the development of polder islands in the Laguna de Bay, addressing the water quantity and quality problems and focusing on the application of the decision support system.

  15. 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

  16. Rough Faults, Distributed Weakening, and Off-Fault Deformation

    NASA Astrophysics Data System (ADS)

    Griffith, W. A.; Nielsen, S. B.; di Toro, G.; Smith, S. A.; Niemeijer, A. R.

    2009-12-01

    We report systematic spatial variations of fault rocks along non-planar strike-slip faults cross-cutting the Lake Edison Granodiorite, Sierra Nevada, California (Sierran Wavy Fault) and the Lobbia outcrops of the Adamello Batholith in the Italian Alps (Lobbia Wavy Fault). In the case of the Sierran fault, pseudotachylyte formed at contractional fault bends, where it is found as thin (1-2 mm) fault-parallel veins. Epidote and chlorite developed in the same seismic context as the pseudotachylyte and are especially abundant in extensional fault bends. We argue that the presence of fluids, as illustrated by this example, does not necessarily preclude the development of frictional melt. In the case of the Lobbia fault, pseudotachylyte is present in variable thickness along the length of the fault, but the pseudotachylyte veins thicken and pool in extensional bends. The Lobbia fault surface is self-affine, and we conduct a quantitative analysis of microcrack distribution, stress, and friction along the fault. Numerical modeling results show that opening in extensional bends and localized thermal weakening in contractional bends counteract resistance encountered by fault waviness, resulting in an overall weaker fault than suggested by the corresponding static friction coefficient. Models also predict stress redistribution around bends in the faults which mirror microcrack distributions, indicating significant elastic and anelastic strain energy is dissipated into the wall rocks due to non-planar fault geometry. Together these observations suggest that, along non-planar faults, damage and energy dissipation occurs along the entire fault during slip, rather than being confined to the region close to the crack tip as predicted by classical fracture mechanics.

  17. Waterbirds (other than Laridae) nesting in the middle section of Laguna Cuyutlán, Colima, México.

    PubMed

    Mellink, Eric; Riojas-López, Mónica E

    2008-03-01

    Laguna de Cuyutlán, in the state of Colima, Mexico, is the only large coastal wetland in a span of roughly 1150 km. Despite this, the study of its birds has been largely neglected. Between 2003 and 2006 we assessed the waterbirds nesting in the middle portion of Laguna Cuyutlán, a large tropical coastal lagoon, through field visits. We documented the nesting of 15 species of non-Laridae waterbirds: Neotropic Cormorant (Phalacrocorax brasilianus), Tricolored Egret (Egretta tricolor), Snowy Egret (Egretta thula), Little Blue Heron (Egretta caerulea), Great Egret (Ardea alba), Cattle Egret (Bubulcus ibis), Black-crowned Night-heron (Nycticorax nycticorax), Yellow-crowned Night-heron (Nyctanassa violacea), Green Heron (Butorides virescens), Roseate Spoonbill (Platalea ajaja), White Ibis (Eudocimus albus), Black-bellied Whistling-duck (Dendrocygna autumnalis), Clapper Rail (Rallus longirostris), Snowy Plover (Charadrius alexandrinus), and Black-necked Stilt (Himantopus mexicanus). These add to six species of Laridae known to nest in that area: Laughing Gulls (Larus atricilla), Royal Terns (Thalasseus maximus), Gull-billed Terns (Gelochelidon nilotica), Forster's Terns (S. forsteri), Least Terns (Sternula antillarum), and Black Skimmer (Rynchops niger), and to at least 57 species using it during the non-breeding season. With such bird assemblages, Laguna Cuyutlán is an important site for waterbirds, which should be given conservation status.

  18. Diagnosable systems for intermittent faults

    NASA Technical Reports Server (NTRS)

    Mallela, S.; Masson, G. M.

    1978-01-01

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

  19. Creeping Faults and Seismicity: Lessons From The Hayward Fault, California

    NASA Astrophysics Data System (ADS)

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

    While faults remain mostly locked between large strain releasing events, they can dissipate some of the accumulating elastic strain through creep. One such fault that releases a significant fraction of accumulating strain by creep is the Hayward fault in the San Francisco Bay region of California. The seismic risk associated with creeping faults such as the Hayward fault will depend in part on the net rate of moment accu- mulation (slip deficit) on the fault. Using a visco-elastic finite-element model driven by far field plate motions, we have investigated how the specific geometry of locked and free portions of the fault, and the interactions between the fault zone and the sur- rounding lithosphere influence creep on the fault plane and thus the seismic risk. In contrast to previous studies of the effects of the geometry of locked patches on the surface creep rate that specified rates on those patches, we specify only "creepable" regions and allow the system to adjust the creep rate. With our approach, we can infer fault zone geometries and physical properties that can produce the observed surface creep on the Hayward fault letting the rheology, geometry, and mechanics of sys- tem determine patterns of creep on the fault plane. Our results show that the creep rate decreases smoothly moving toward the locked patches. This leads to "creepable" (low friction) areas that accumulate a high slip deficit as compared to other low fric- tion segments of the fault. A comparison of the creep pattern from our results with Hayward fault micro-seismicity indicates that events cluster in the "creepable" re- gions with a creeping-velocity gradient that leads to a significant strain accumulation rate in the elastic material surrounding the creeping fault. This correlation provides an additional tool to map deformation patterns and strain accumulation on the fault. Micro-seismicity, surface deformation, and geodynamic modeling combine to allow us to refine our estimation of net

  20. Changes in fault length distributions due to fault linkage

    NASA Astrophysics Data System (ADS)

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

    2010-01-01

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

  1. Diatom diversity and paleoenvironmental changes in Laguna Potrok Aike, Patagonia: the ~ 50 kyr PASADO sediment record

    NASA Astrophysics Data System (ADS)

    Recasens, C.; Ariztegui, D.; Maidana, N. I.

    2012-12-01

    Laguna Potrok Aike is a maar lake located in the southernmost Argentinean Patagonia, in the province of Santa Cruz. Being one of the few permanent lakes in the area, it provides an exceptional and continuous sedimentary record. The sediment cores from Laguna Potrok Aike, obtained in the framework of the ICDP-sponsored project PASADO (Potrok Aike Maar Lake Sediment Archive Drilling Program), were sampled for diatom analysis in order to reconstruct a continuous history of hydrological and climatic changes since the Late Pleistocene. Diatoms are widely used to characterize and often quantify the impact of past environmental changes in aquatic systems. We use variations in diatom concentration and in their dominant assemblages, combined with other proxies, to track these changes. Diatom assemblages were analyzed on the composite core 5022-2CP with a multi-centennial time resolution. The total composite profile length of 106.09 mcd (meters composite depth) was reduced to 45.80 m cd-ec (event-corrected composite profile) of pelagic deposits once gaps, reworked sections, and tephra deposits were removed. This continuous deposit spans the last ca. 51.2 cal. ka BP. Previous diatomological analysis from the core catcher samples of core 5022-1D, allowed us to determine the dominant diatom assemblages in this lake and select the sections where higher temporal resolution was needed. Over 200 species, varieties and forms were identified in the sediment record, including numerous endemic species and others which can be new to science. Among these, a new species has been described: Cymbella gravida sp. nov. Recasens and Maidana. The quantitative analysis of the sediment record reveals diatom abundances reaching 460 million valves per gram of dry sediment, with substantial fluctuations through time. Variations in the abundance and species distribution point toward lake level variations, changes in nutrient input or even periods of ice-cover in the lake. The top meters of the record

  2. The Maars of the Tuxtla Volcanic Field: the Example of 'laguna Pizatal'

    NASA Astrophysics Data System (ADS)

    Espindola, J.; Zamora-Camacho, A.; Hernandez-Cardona, A.; Alvarez del Castillo, E.; Godinez, M.

    2013-12-01

    Los Tuxtlas Volcanic Field (TVF), also known as Los Tuxtlas massif, is a structure of volcanic rocks rising conspicuously in the south-central part of the coastal plains of eastern Mexico. The TVF seems related to the upper cretaceous magmatism of the NW part of the Gulf's margin (e.g. San Carlos and Sierra de Tamaulipas alkaline complexes) rather than to the nearby Mexican Volcanic Belt. The volcanism in this field began in late Miocene and has continued in historical times, The TVF is composed of 4 large volcanoes (San Martin Tuxtla, San Martin Pajapan, Santa Marta, Cerro El Vigia), at least 365 volcanic cones and 43 maars. In this poster we present the distribution of the maars, their size and depths. These maars span from a few hundred km to almost 1 km in average diameter, and a few meters to several tens of meters in depth; most of them filled with lakes. As an example on the nature of these structures we present our results of the ongoing study of 'Laguna Pizatal or Pisatal' (18° 33'N, 95° 16.4'W, 428 masl) located some 3 km from the village of Reforma, on the western side of San Martin Tuxtla volcano. Laguna Pisatal is a maar some 500 meters in radius and a depth about 40 meters from the surrounding ground level. It is covered by a lake 200 m2 in extent fed by a spring discharging on its western side. We examined a succession of 15 layers on the margins of the maar, these layers are blast deposits of different sizes interbedded by surge deposits. Most of the contacts between layers are irregular; which suggests scouring during deposition of the upper beds. This in turn suggests that the layers were deposited in a rapid series of explosions, which mixed juvenile material with fragments of the preexisting bedrock. We were unable to find the extent of these deposits since the surrounding areas are nowadays sugar cane plantations and the lake has overspilled in several occassions.

  3. A 5000 Year Record of Andean South American Summer Monsoon Variability from Laguna de Ubaque, Colombia

    NASA Astrophysics Data System (ADS)

    Rudloff, O. M.; Bird, B. W.; Escobar, J.

    2014-12-01

    Our understanding of Northern Hemisphere South American summer monsoon (SASM) dynamics during the Holocene has been limited by the small number of terrestrial paleoclimate records from this region. In order to increase our knowledge of SASM variability and to better inform our predictions of its response to ongoing rapid climate change, we require high-resolution paleoclimate records from the Northern Hemisphere Andes. To this end, we present sub-decadally resolved sedimentological and geochemical data from Laguna de Ubaque that spans the last 5000 years. Located in the Eastern Cordillera of the Colombian Andes, Laguna de Ubaque (2070 m asl) is a small, east facing moraine-dammed lake in the upper part of the Rio Meta watershed near Bogotá containing finely laminated clastic sediments. Dry bulk density, %organic matter, %carbonate and magnetic susceptibility (MS) results from Ubaque suggest a period of intense precipitation between 3500 and 2000 years BP interrupted by a 300 yr dry interval centered at 2700 years BP. Following this event, generally drier conditions characterize the last 2000 years. Although considerably lower amplitude than the middle Holocene pluvial events, variability in the sedimentological data support climatic responses during the Medieval Climate Anomaly (MCA; 900 to 1200 CE) and Little Ice Age (LIA; 1450 to 1900 CE) that are consistent with other records of local Andean conditions. In particular, reduced MS during the MCA suggests a reduction in terrestrial material being washed into the lake as a result of generally drier conditions. The LIA on the other hand shows a two phase structure with increased MS between 1450 and 1600 CE, suggesting wetter conditions during the onset of the LIA, and reduced MS between 1600 and 1900 CE, suggesting a return to drier conditions during the latter part of the LIA. These LIA trends are similar to the Quelccaya accumulation record, possibly supporting an in-phase relationship between the South American

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Impact of Water Resorts Development along Laguna de Bay on Groundwater Resources

    NASA Astrophysics Data System (ADS)

    Jago-on, K. A. B.; Reyes, Y. K.; Siringan, F. P.; Lloren, R. B.; Balangue, M. I. R. D.; Pena, M. A. Z.; Taniguchi, M.

    2014-12-01

    Rapid urbanization and land use changes in areas along Laguna de Bay, one of the largest freshwater lake in Southeast Asia, have resulted in increased economic activities and demand for groundwater resources from households, commerce and industries. One significant activity that can affect groundwater is the development of the water resorts industry, which includes hot springs spas. This study aims to determine the impact of the proliferation of these water resorts in Calamba and Los Banos, urban areas located at the southern coast of the lake on the groundwater as a resource. Calamba, being the "Hot Spring Capital of the Philippines", presently has more than 300 resorts, while Los Banos has at least 38 resorts. Results from an initial survey of resorts show that the swimming pools are drained/ changed on an average of 2-3 times a week or even daily during peak periods of tourist arrivals. This indicates a large demand on the groundwater. Monitoring of actual groundwater extraction is a challenge however, as most of these resorts operate without water use permits. The unrestrained exploitation of groundwater has resulted to drying up of older wells and decrease in hot spring water temperature. It is necessary to strengthen implementation of laws and policies, and enhance partnerships among government, private sector groups, civil society and communities to promote groundwater sustainability.

  11. Estimating floodplain sedimentation in the Laguna de Santa Rosa, Sonoma County, CA

    USGS Publications Warehouse

    Curtis, Jennifer A.; Flint, Lorraine E.; Hupp, Cliff R.

    2013-01-01

    We present a conceptual and analytical framework for predicting the spatial distribution of floodplain sedimentation for the Laguna de Santa Rosa, Sonoma County, CA. We assess the role of the floodplain as a sink for fine-grained sediment and investigate concerns regarding the potential loss of flood storage capacity due to historic sedimentation. We characterized the spatial distribution of sedimentation during a post-flood survey and developed a spatially distributed sediment deposition potential map that highlights zones of floodplain sedimentation. The sediment deposition potential map, built using raster files that describe the spatial distribution of relevant hydrologic and landscape variables, was calibrated using 2 years of measured overbank sedimentation data and verified using longer-term rates determined using dendrochronology. The calibrated floodplain deposition potential relation was used to estimate an average annual floodplain sedimentation rate (3.6 mm/year) for the ~11 km2 floodplain. This study documents the development of a conceptual model of overbank sedimentation, describes a methodology to estimate the potential for various parts of a floodplain complex to accumulate sediment over time, and provides estimates of short and long-term overbank sedimentation rates that can be used for ecosystem management and prioritization of restoration activities.

  12. Vegetation and climate history from Laguna de Río Seco, Sierra Nevada, southern Spain

    NASA Astrophysics Data System (ADS)

    Anderson, R. S.; Jimenez-Moreno, G.

    2010-12-01

    The largest mountain range in southern Spain - the Sierra Nevada - is an immense landscape with a rich biological and cultural heritage. Rising to 3,479 m at the summit of Mulhacén, the range was extensively glaciated during the late Pleistocene. Subsequent melting of cirque glaciers allowed formation of numerous small lakes and wetlands. One south-facing basin contains Laguna de Río Seco, a small lake at ca. 3020 m elevation, presently above potential treeline. Pollen analysis of sediment cores documents over 11,000 calendar years of vegetation change there. The early record, to ca. 5,700 cal yr BP, is dominated by pine pollen, with birch, deciduous oak, and grass, with an understory of shrubs types. Pine trees probably never grew at the elevation of the lake, but aquatic microfossils indicate lake levels were highest prior to ca. 7,800 cal yr BP, perhaps as a result of heavy winter precipitation, and early Holocene expansion of the ITCZ. Drier conditions commenced by 5,700 cal yr BP, shown by declines in wetland pollen, and increases in high elevation steppe shrubs more common today (juniper, sage, and others). The local and regional impact of humans increased substantially after ca. 2700 years ago, with the regional loss of pine forest or woodland, increases in pollen and spore types associated with pasturing, and olive cultivation at lower elevations.

  13. Hantavirus pulmonary syndrome in northwestern Argentina: circulation of Laguna Negra virus associated with Calomys callosus.

    PubMed

    Levis, Silvana; Garcia, Jorge; Pini, Noemí; Calderón, Gladys; Ramírez, Josefina; Bravo, Daniel; St Jeor, Stephen; Ripoll, Carlos; Bego, Mariana; Lozano, Elena; Barquez, Rubén; Ksiazek, Thomas G; Enria, Delia

    2004-11-01

    The purpose of this study was to characterize the hantaviruses circulating in northwestern Argentina. Human and rodent studies were conducted in Yuto, where most cases of hantavirus pulmonary syndrome (HPS) occur. Partial virus genome sequences were obtained from the blood of 12 cases of HPS, and from the lungs of 4 Calomys callosus and 1 Akodon simulator. Phylogenetic analysis showed that three genotypes associated with HPS circulate in Yuto. Laguna Negra (LN) virus, associated with C. laucha in Paraguay, was identified for the first time in Argentina; it was recovered from human cases and from C. callosus samples. The high sequence identity between human and rodent samples implicated C. callosus as the primary rodent reservoir for LN virus in Yuto. The genetic analysis showed that the Argentinian LN virus variant differed 16.8% at the nucleotide level and 2.9% at the protein level relative to the Paraguayan LN virus. The other two hantavirus lineages identified were the previously known Bermejo and Oran viruses.

  14. Stratigraphy and Characterization of Volcanic Deposits on the Northwestern Flanks of Mt. Makiling, Laguna, Philippines

    NASA Astrophysics Data System (ADS)

    Ybanez, R. L.; Bonus, A. A. B.; Judan, J. M.; Racoma, B. A.; Morante, K. A. M.; Balangue, M. I. R. D.

    2014-12-01

    Mt. Makiling is an inactive stratovolcano located in the province of Laguna. Semi-detailed geologic field mapping on the northwestern low-level flanks and apron of the volcano was conducted. Exposures reveal a volcanic terrain hosting a wide variety of volcanic rocks: lava flows, pyroclastic surges, pyroclastic flows, and tuff deposits. Stratigraphic logging of the volcanic deposits showed differences in occurrence of the deposit types as well as their characteristics. The pyroclastic flow deposits are found at the base of the column overlain by pyroclastic surges which were more common in the area. Capping the pyroclastic surges is a thin layer of tuffaceous units. Isolated deposits of lava flows of andesitic composition were mapped in the western flank of Mt. Makiling. These varying volcanic deposits are derived from different eruptive activities of Mt. Makiling, with at least three separate eruptive episodes indicated by the exposed deposits. Two separate explosive eruptions are marked by two different pyroclastic deposits, while an effusive episode, marked by andesitic lava flows, can also be identified. The pyroclastic surge deposit is uncharacteristically thick, around a hundred meters or more exposed, providing further questions as to the magnitude of past eruptions or the mechanism of pyroclastic material deposition around the volcano. Mt. Makiling, thus, has historically undergone different eruption types, but still releases generally the same material composition across varying deposits: intermediate or andesitic composition. This is consistent with the trend of Philippine volcanoes, and with the Macolod corridor which hosts this volcanic system.

  15. Laguna Negra Virus Infection Causes Hantavirus Pulmonary Syndrome in Turkish Hamsters (Mesocricetus brandti).

    PubMed

    Hardcastle, K; Scott, D; Safronetz, D; Brining, D L; Ebihara, H; Feldmann, H; LaCasse, R A

    2016-01-01

    Laguna Negra virus (LNV) is a New World hantavirus associated with severe and often fatal cardiopulmonary disease in humans, known as hantavirus pulmonary syndrome (HPS). Five hamster species were evaluated for clinical and serologic responses following inoculation with 4 hantaviruses. Of the 5 hamster species, only Turkish hamsters infected with LNV demonstrated signs consistent with HPS and a fatality rate of 43%. Clinical manifestations in infected animals that succumbed to disease included severe and rapid onset of dyspnea, weight loss, leukopenia, and reduced thrombocyte numbers as compared to uninfected controls. Histopathologic examination revealed lung lesions that resemble the hallmarks of HPS in humans, including interstitial pneumonia and pulmonary edema, as well as generalized infection of endothelial cells and macrophages in major organ tissues. Histologic lesions corresponded to the presence of viral antigen in affected tissues. To date, there have been no small animal models available to study LNV infection and pathogenesis. The Turkish hamster model of LNV infection may be important in the study of LNV-induced HPS pathogenesis and development of disease treatment and prevention strategies.

  16. The ambient acoustic environment in Laguna San Ignacio, Baja California Sur, Mexico.

    PubMed

    Seger, Kerri D; Thode, Aaron M; Swartz, Steven L; Urbán, Jorge R

    2015-11-01

    Each winter gray whales (Eschrichtius robustus) breed and calve in Laguna San Ignacio, Mexico, where a robust, yet regulated, whale-watching industry exists. Baseline acoustic environments in LSI's three zones were monitored between 2008 and 2013, in anticipation of a new road being paved that will potentially increase tourist activity to this relatively isolated location. These zones differ in levels of both gray whale usage and tourist activity. Ambient sound level distributions were computed in terms of percentiles of power spectral densities. While these distributions are consistent across years within each zone, inter-zone differences are substantial. The acoustic environment in the upper zone is dominated by snapping shrimp that display a crepuscular cycle. Snapping shrimp also affect the middle zone, but tourist boat transits contribute to noise distributions during daylight hours. The lower zone has three source contributors to its acoustic environment: snapping shrimp, boats, and croaker fish. As suggested from earlier studies, a 300 Hz noise minimum exists in both the middle and lower zones of the lagoon, but not in the upper zone.

  17. Fault diagnosis of analog circuits

    NASA Astrophysics Data System (ADS)

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

    1985-08-01

    Theory and algorithms associated with four main categories of modern techniques used to locate faults in analog circuits are presented. These four general approaches are: the fault dictionary (FDA), the parameter identification (PIA), the fault verification (FVA), and the approximation (AA) approaches. The preliminaries and problems associated with the FDA, such as fault dictionary construction, the methods of optimum measurement selection, fault isolation criteria, and efficient methods of fault simulation, are discussed. The PIA techniques that utilize either linear or nonlinear systems of equations for identification of network elements are examined. Description of the FVA includes node-fault diagnosis, branch-fault diagnosis, subnetwork testability conditions, as well as combinatorial techniques, the failure-bound technique, and the network decomposition technique. In the AA, probabilistic methods and optimization-based methods are considered. In addition, the artificial intelligence technique and the different measures of testability are presented. A series of block diagrams is included.

  18. 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.

  19. Fault-Mechanism Simulator

    ERIC Educational Resources Information Center

    Guyton, J. W.

    1972-01-01

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

  20. 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.

  1. Row fault detection system

    DOEpatents

    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.

  2. Row fault detection system

    DOEpatents

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

    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.

  3. 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

  4. 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.

  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. Effect of surrounding fault on distributed fault of blind reverse fault in sedimentary basin - Uemachi Faults, Osaka Basin, Southwest Japan -

    NASA Astrophysics Data System (ADS)

    Inoue, N.

    2012-12-01

    Several large cities and metropolitan areas, such as Osaka and Kobe are located in the Osaka basin, which has been filled by the Pleistocene Osaka group and the later sediments. 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 various geological, geophysical surveys, such as seismic reflection, micro tremor, gravity surveys and deep boreholes, revealed the complex basement configuration along the Uemachi faults. The depth of the basement is shallow in the central part of the Osaka plain. The Uemachi faults are locates on the western side of the basement upland. In the central part of the Uemachi faults, the displacement decreases. The fault model of the Uemachi faults consists of the two parts, the north and south parts. The NE-SW trending branch faults, Suminoe and Sakuragawa flexures, are also recognized based on various surveys around the central part. Kusumoto et al. (2001) reported that surrounding faults enable to form the basement configuration without the Uemachi faults model based on a dislocation model. Inoue et al. (2011) 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 of 7 faults including the Uemachi faults. In this study, the Osaka-wan fault was considered for the dislocation model. The results show the basement configuration including NE-SW branch faults. The basement configuration differs from the subsurface structure derived from the investigation of abundance geotechnical borehole data around the central part of the Uemachi faults. The tectonic developing process including the erosion and sea level change are require to understanding the structure from the basement to the surface of the Uemachi Fault Zone. This research is partly funded by the Comprehensive

  7. Carbon and nitrogen isotope composition of core catcher samples from the ICDP deep drilling at Laguna Potrok Aike (Patagonia, Argentina)

    NASA Astrophysics Data System (ADS)

    Luecke, Andreas; Wissel, Holger; Mayr*, Christoph; Oehlerich, Markus; Ohlendorf, Christian; Zolitschka, Bernd; Pasado Science Team

    2010-05-01

    The ICDP project PASADO aims to develop a detailed paleoclimatic record for the southern part of the South American continent from sediments of Laguna Potrok Aike (51°58'S, 70°23'W), situated in the Patagonian steppe east of the Andean cordillera and north of the Street of Magellan. The precursor project SALSA recovered the Holocene and Late Glacial sediment infill of Laguna Potrok Aike and developed the environmental history of the semi-arid Patagonian steppe by a consequent interdisciplinary multi-proxy approach (e.g. Haberzettl et al., 2007). From September to November 2008 the ICDP deep drilling took place and successfully recovered in total 510 m of sediments from two sites resulting in a composite depth of 106 m for the selected main study Site 2. A preliminary age model places the record within the last 50.000 years. During the drilling campaign, the core catcher content of each drilled core run (3 m) was taken as separate sample to be shared and distributed between involved laboratories long before the main sampling party. A total of 70 core catcher samples describe the sediments of Site 2 and will form the base for more detailed investigations on the palaeoclimatic history of Patagonia. We here report on the organic carbon and nitrogen isotope composition of bulk sediment and plant debris of the core catcher samples. Similar investigations were performed for Holocene and Late Glacial sediments of Laguna Potrok Aike revealing insights into the organic matter dynamics of the lake and its catchment as well as into climatically induced hydrological variations with related lake level fluctuations (Mayr et al., 2009). The carbon and nitrogen content of the core catcher fine sediment fraction (<200 µm) is low to very low (around 1 % and 0.1 %, respectively) and requires particular attention in isotope analysis. The carbon isotope composition shows comparably little variation around a value of -26.0 per mil. The positive values of the Holocene and the Late

  8. Origin and evolution of the Laguna Potrok Aike maar (Southern Patagonia, Argentina) as revealed by seismic data

    NASA Astrophysics Data System (ADS)

    Gebhardt, C.; de Batist, M. A.; Niessen, F.; Anselmetti, F.; Ariztegui, D.; Haberzettl, T.; Ohlendorf, C.; Zolitschka, B.

    2009-12-01

    Seismic reflection and refraction data provide insights into the sedimentary infill and the underlying volcanic structure of Laguna Potrok Aike, a maar lake situated in the Pali Aike Volcanic Field, Southern Patagonia. The lake has a diameter of ~3.5 km, a maximum water depth of ~100 m and a presumed age of ~770 ka. Its sedimentary regime is influenced by climatic and hydrologic conditions related to the Antarctic Circumpolar Current, the Southern Hemispheric Westerlies and sporadic outbreaks of Antarctic polar air masses. Multiproxy environmental reconstructions of the last 16 ka document that this terminal lake is highly sensitive to climate change. Laguna Potrok Aike has recently become a major focus of the International Continental Scientific Drilling Program and was drilled down to 100 m below lake floor in late 2008 within the PASADO project. The sediments are likely to contain a continental record spanning the last ca. 80 kyrs unique in the South American realm. Seismic reflection data show relatively undisturbed, stratified lacustrine sediments at least in the upper ~100 m of the sedimentary infill but are obscured possibly by gas and/or coarser material in larger areas. A model calculated from seismic refraction data reveals a funnel-shaped structure embedded in the sandstone rocks of the surrounding Santa Cruz Formation. This funnel structure is filled by lacustrine sediments of up to 370 m in thickness. These can be separated into two distinct subunits with low acoustic velocities of 1500-1800 m s-1 in the upper subunit pointing at unconsolidated lacustrine muds, and enhanced velocities of 2000-2350 m s-1 in the lower subunit. Below these lacustrine sediments, a unit of probably volcanoclastic origin is observed (>2400 m s-1). This sedimentary succession is well comparable to other well-studied sequences (e.g. Messel and Baruth maars, Germany), confirming phreatomagmatic maar explosions as the origin of Laguna Potrok Aike.

  9. 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.

  10. The Development of a Restless Rhyolite Magma Chamber at Laguna del Maule, Chile

    NASA Astrophysics Data System (ADS)

    Andersen, N.; Singer, B. S.; Jicha, B. R.; Fierstein, J.; Vazquez, J. A.

    2013-12-01

    The Laguna del Maule (LdM) volcanic field is a site of rapid crustal deformation at rates in excess of 200 mm/yr since 2007. The uplift is centered in the 16 km diameter LdM lake basin, which is ringed by 21 rhyolite domes and coulees erupted since the last glacial retreat. The lack of previously common andesite and dacite eruptions since 19 ka and coherent major and trace element variation throughout post-glacial time suggests the presence of a large silicic magma body beneath the LdM basin. Assimilation-fractional crystallization modeling predicts the rhyolites evolved at 5 km depth by 73% fractionation of a basaltic parent and modest assimilation of granodiorite accounting for up to 20% of the highest silica rhyolite. AFC processes dominate the evolution from basalt, however the differentiation of the silicic magma is complicated by liquid extraction from crystal mush, remelting of cumulate by intruding basalt, and trace element diffusion. Two-oxide thermometry indicates a relatively hot, oxidized system with eruptive temperatures ranging from 760 - 850° C and fO2 at QFM+2. Pilot ion microprobe 238U-230Th dating of zircon rims suggests the shallow LdM magma system was assembled over a period of 100-200 kyr. 40Ar/39Ar geochronology and field relationships reveal the post-glacial silicic volcanism occurred in two phases. Phase 1 began approximately coincident with deglaciation at 25 ka with the eruption of the rhyolite East of Presa Laguna del Maule. Over the next 6 ky, 6 small rhyodacite domes, a larger rhyodacite flow, and 4 andesite flows erupted in the NW basin and two silicic domes 12 km to the SE. Phase 1 culminates with the eruption of the Espejos rhyolite near the N shore of the lake at 19 ka. The locus of volcanism then migrates SE and phase 2 begins at ~10 ka with the eruption of the Cari Launa rhyolite and the early flows of the Barrancas complex. This period is more voluminous, erupting 4.8 km3 compared to 1.7 km3 during phase 1. Phase 2 produced

  11. 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

  12. Hydrocarbon concentrations in the American oyster, Crassostrea virginica, in Laguna de Terminos, Campeche, Mexico

    SciTech Connect

    Gold-Bouchot, G.; Norena-Barroso, E.; Zapata-Perez, O.

    1995-02-01

    Laguna de Terminos is a 2,500 km{sup 2} coastal lagoon in the southern Gulf of Mexico, located between 18{degrees} 20` and 19{degrees} 00` N, and 91{degrees} 00` and 92{degrees} 20` W (Figure 1). It is a shallow lagoon, with a mean depth of 3.5 m and connected to the Gulf of Mexico through two permanent inlets, Puerto Real to the east and Carmen to the west. Several rivers, most of them from the Grijalva-Usumacinta basin (the largest in Mexico and second largest in the Gulf of Mexico), drain into the lagoon with a mean annual discharge of 6 X 10{sup 9} m{sup 3}/year. This lagoon has been studied systematically, and is probably one of the best known in Mexico. An excellent overview of this lagoon can be found in Yanez-Arancibia and Day. The continental shelf north of Terminos, the Campeche Bank, is the main oil-producing zone in Mexico with a production of about 2 X 10{sup 6} barrels/day. It is also the main shrimp producer in the southern Gulf, with a mean annual catch of 18,000 tonnes/year, which represents 38 to 50% of the national catch in the Gulf of Mexico. The economic importance of this region, along with its extremely high biodiversity, both in terms of species and habitats, has prompted the Mexican government to study the creation of a wildlife refuge around Terminos. Thus, it is very important to know the current levels of pollutants in this area, as a contribution to the management plan of the proposed protected area. This paper looks at hydrocarbon concentrations in oyster tissue. 14 refs., 3 figs., 21 tabs.

  13. Dynamics of a large, restless, rhyolitic magma system at Laguna del Maule, southern Andes, Chile

    USGS Publications Warehouse

    Singer, Brad S.; Andersen, Nathan L.; Le Mével, Hélène; Feigl, Kurt L.; DeMets, Charles; Tikoff, Basil; Thurber, Clifford H.; Jicha, Brian R.; Cardonna, Carlos; Córdova, Loreto; Gil, Fernando; Unsworth, Martyn J.; Williams-Jones, Glyn; Miller, Craig W.; Fierstein, Judith; Hildreth, Edward; Vazquez, Jorge A.

    2014-01-01

    Explosive eruptions of large-volume rhyolitic magma systems are common in the geologic record and pose a major potential threat to society. Unlike other natural hazards, such as earthquakes and tsunamis, a large rhyolitic volcano may provide warning signs long before a caldera-forming eruption occurs. Yet, these signs—and what they imply about magma-crust dynamics—are not well known. This is because we have learned how these systems form, grow, and erupt mainly from the study of ash flow tuffs deposited tens to hundreds of thousands of years ago or more, or from the geophysical imaging of the unerupted portions of the reservoirs beneath the associated calderas. The Laguna del Maule Volcanic Field, Chile, includes an unusually large and recent concentration of silicic eruptions. Since 2007, the crust there has been inflating at an astonishing rate of at least 25 cm/yr. This unique opportunity to investigate the dynamics of a large rhyolitic system while magma migration, reservoir growth, and crustal deformation are actively under way is stimulating a new international collaboration. Findings thus far lead to the hypothesis that the silicic vents have tapped an extensive layer of crystal-poor, rhyolitic melt that began to form atop a magmatic mush zone that was established by ca. 20 ka with a renewed phase of rhyolite eruptions during the Holocene. Modeling of surface deformation, magnetotelluric data, and gravity changes suggest that magma is currently intruding at a depth of ~5 km. The next phase of this investigation seeks to enlarge the sets of geophysical and geochemical data and to use these observations in numerical models of system dynamics.

  14. Disentangling High Frequency Climate Oscillations In A Volcanic Setting Laguna Lejia, Chile

    NASA Astrophysics Data System (ADS)

    Saltzman, S. H.; Ukstins Peate, I.; Giralt, S.; Peate, D. W.; van Alderwerelt, B. M.

    2015-12-01

    Our understanding of the tropics response to periods of rapid climate change such as CAPE I and the Younger Dryas is limited. Laguna Lejia (23°30'0" S 67°42'0" E ~4,300m asl), Chile is a small alkaline paleolake located in the central Altiplano. The volcanoes Lascar, Chiliques, Aguas Calientes and Acamarachi surround it. 1-3 mm laminations in calcareous clay sediments deposited on the southern terrace of Lejia record high-resolution chemical variability in the lake. Preliminary U-Th ages range from 19,567 +739/- 734 yr to 4208 +431/-429 yr, indicating that the Lejia terrace deposits span both CAPE I and the Younger Dryas, periods of rapid global climate change. Changes in the major and trace element composition, δ18O and δ13 C isotopic ratios, and the amount of Li, Mg, Ca, and Sr that can be readily leached from high magnesium smectite clays provide a direct proxy for hydrologic fluctuations. A climate signal can be detected through reoccurring trends in the chemical variability of these sediments; however, the detection of this signal is complicated by interaction with surrounding volcanic edifices. Statistical methods such as PCA analyses using R have been implemented to separate groupings of volcanic controlled elemental fluctuations (Fe, Zr, Nd, Ti, and Al) from ones under the influence of climate. Spectral analyses have been applied to high-resolution major element data collected on Lejia's paleoshores tufa deposits. Data was collected on Ca, Mg and As at .5 um intervals using a Jeol JXA- 8230 Electron Microprobe at the University of Iowa, Earth and Environmental Sciences. These analyses provided statistical evidence for cyclisity at intervals of 5-15 um and 75-150 um in the banding of the tufas. While previous literature attributes the larger bands to annual chemical cycles the origin of the smaller bands is currently under investigation.

  15. Continued Rapid Uplift at Laguna del Maule Volcanic Field (Chile) from 2007 through 2014

    NASA Astrophysics Data System (ADS)

    Le Mével, H.; Feigl, K. L.; Cordova, L.; DeMets, C.; Lundgren, P.

    2014-12-01

    The current rate of uplift at Laguna del Maule (LdM) volcanic field in Chile is among the highest ever observed geodetically for a volcano that is not actively erupting. Using data from interferometric synthetic aperture radar (InSAR) and the Global Positioning System (GPS) recorded at five continuously operating stations, we measure the deformation field with dense sampling in time (1/day) and space (1/hectare). These data track the temporal evolution of the current unrest episode from its inception (sometime between 2004 and 2007) to vertical velocities faster than 200 mm/yr that continue through (at least) July 2014. Building on our previous work, we evaluate the temporal evolution by analyzing data from InSAR (ALOS, TerraSAR-X, TanDEM-X) and GPS [http://dx.doi.org/ 10.1093/gji/ggt438]. In addition, we consider InSAR data from (ERS, ENVISAT, COSMO-Skymed, and UAVSAR), as well as constraints from magneto-telluric (MT), seismic, and gravity surveys. The goal is to test the hypothesis that a recent magma intrusion is feeding a large, existing magma reservoir. What will happen next? To address this question, we analyze the temporal evolution of deformation at other large silicic systems such as Yellowstone, Long Valley, and Three Sisters, during well-studied episodes of unrest. We consider several parameterizations, including piecewise linear, parabolic, and Gaussian functions of time. By choosing the best-fitting model, we expect to constrain the time scales of such episodes and elucidate the processes driving them.

  16. Modern sedimentation patterns in Laguna de Medina, Southern Spain, derived from lake surface and soil samples

    NASA Astrophysics Data System (ADS)

    van ´t Hoff, Jasmijn; Schröder, Tabea; Reicherter, Klaus; Held, Peter; Melles, Martin

    2016-04-01

    In September 2014 and March 2015, a 25.66 m long sediment core (Co1313) was retrieved from the centre of Laguna de Medina, a small endorheic salt lake in Cádiz, SW Spain. This record covers the last 9.000 years, thus providing an unique archive for Holocene climatic and environmental changes with extraordinary high temporal resolution. For a better understanding of the palaeoenvironmental proxies to be analysed on the sediment core, the modern processes of sediment formation in the lake and its catchment under known environmental conditions were investigated on a set of 46 lake sediment surface samples and 32 soil surface sediment samples from the lake and the close surroundings, respectively. These samples were analysed for bulk mineralogy (XRD), chemical composition (XRF), grain-size distribution (laser scanner), and carbonate, total organic carbon (TOC), nitrogen (TN) and sulphur (TS) contents (elemental analyser). Based on the mineralogical, geochemical and granulometrical data, the lake can be divided into four zones. The northern shore is characterized by particularly high quartz contents and coarse grain sizes. This reflects input from ancient terraces of the Guadalete River that are exposed in that area. The southern shore is characterised by high calcite contents due to sediment supply from the Cretaceous ´Capas rojaś, a series of Subbetic deep-water marl- and limestones. The southeastern and to a lesser extend the northwestern shores show particularly high dolomite contents, reflecting the Triassic dolomites outcroping in the southeastern catchment. The southeastern shore furthermore is also influenced by strong terrestrial input of the Triassic Keuper facies from the most important inlet, Arroyo Fuente Bermeja, as reflected by high contents of Ti, K, Al, Fe, Rb in the lake sediments. The last zone comprises only a small part of the western shore and is characterized by a relatively high gypsum amount. This does not reflect the geology in the catchment

  17. Rickettsia bellii, Rickettsia amblyommii, and Laguna Negra hantavirus in an Indian reserve in the Brazilian Amazon

    PubMed Central

    2014-01-01

    Background The purpose of this study was to identify the presence of rickettsia and hantavirus in wild rodents and arthropods in response to an outbreak of acute unidentified febrile illness among Indians in the Halataikwa Indian Reserve, northwest of the Mato Grosso state, in the Brazilian Amazon. Where previously surveillance data showed serologic evidence of rickettsia and hantavirus human infection. Methods The arthropods were collected from the healthy Indian population and by flagging vegetation in grassland or woodland along the peridomestic environment of the Indian reserve. Wild rodents were live-trapped in an area bordering the reserve limits, due the impossibility of capturing wild animals in the Indian reserve. The wild rodents were identified based on external and cranial morphology and karyotype. DNA was extracted from spleen or liver samples of rodents and from invertebrate (tick and louse) pools, and the molecular characterization of the rickettsia was through PCR and DNA sequencing of fragments of two rickettsial genes (gltA and ompA). In relation to hantavirus, rodent serum samples were serologically screened by IgG ELISA using the Araraquara-N antigen and total RNA was extracted from lung samples of IgG-positive rodents. The amplification of the complete S segment was performed. Results A total of 153 wild rodents, 121 louse, and 36 tick specimens were collected in 2010. Laguna Negra hantavirus was identified in Calomys callidus rodents and Rickettsia bellii, Rickettsia amblyommii were identified in Amblyomma cajennense ticks. Conclusions Zoonotic diseases such as HCPS and spotted fever rickettsiosis are a public health threat and should be considered in outbreaks and acute febrile illnesses among Indian populations. The presence of the genome of rickettsias and hantavirus in animals in this Indian reserve reinforces the need to include these infectious agents in outbreak investigations of febrile cases in Indian populations. PMID:24742108

  18. Distribution of phototrophic microbes in the flat laminated microbial mat at Laguna Figueroa, Baja California, Mexico.

    PubMed

    Stolz, J F

    1990-01-01

    The microbial mat community in the saltmarsh/evaporate flat interface at Laguna Figueroa involved in the deposition of laminated sediments was investigated. Pigment analysis, light microscopy and transmission electron microscopy were used to determine the relative abundance and distribution of phototrophic species. The community is vertically stratified into four distinct phototrophic populations. The layering could be distinguished by pigment and species composition. The two layers closest to the surface contained mostly oxygenic phototrophs and chlorophyll a as the primary photosynthetic pigment. Anoxic phototrophs predominated in the bottom two layers with bacteriochlorophylls a and c in the third layer and bacteriochlorophyll a and b in the bottom layer. The surface yellow layer was composed primarily of Navicula, Rhopalodia and other diatom species as well as the cyanobacteria Aphanothece sp. and Phormidium sp. Microcoleus chthonoplasces and Chroococcidiopsis sp. were the major cyanobacteria in the green colored second layer. In the third layer, pinkish-purple in color, purple photographs (Chromatium sp., Thiocapsa roseoparsicina) and filamentous green phototrophs (Chloroflexus sp., Oscillochloris sp.) were abundant. The fourth and deepest photosynthetic layer was salmon colored and composed primarily of Thiocapsa pfennigii, and other purple sulfur phototrophs. The pattern of alternating light (oxygenic community) and dark (anoxygenic community) layering preserved in older laminae is a consequence of this community structure. Study of the flat laminated mat over the 10-year period (1978-1988) including and after its destruction by catastrophic flooding events in 1978 and 1980, showed a succession of stratified communities culminating in the return of Microcoleus and the full compliment of layers by the fall of 1984.

  19. 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.

  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. Fault tolerant control laws

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

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

  2. Estimated natural streamflow in the Rio San Jose upstream from the pueblos of Acoma and Laguna, New Mexico

    USGS Publications Warehouse

    Risser, D.W.

    1982-01-01

    The development of surface and ground water, which began about 1870 in the upper Rio San Jose drainage basin, has decreased the flow of the Rio San Jose on the Pueblo of Acoma and the Pueblo of Laguna. The purpose of this study was to estimate the natural streamflow in the Rio San Jose that would have entered the pueblos if no upstream water development had taken place. Estimates of natural flow were based upon streamflow and precipitation records, historical accounts of streamflow, records of irrigated acreage, and empirically-derived estimates of the effects on streamflow of Bluewater Lake, groundwater withdrawals, and irrigation diversions. Natural streamflow in the Rio San Jose at the western boundary of the Pueblo of Acoma is estimated to be between 13,000 and 15,000 acre-feet per year, based on 55 years of recorded and reconstructed streamflow data from water years 1913 to 1972. Natural streamflow at the western boundary of the Pueblo of Laguna is estimated to be between 17 ,000 and 19,000 acre-feet per year for the same period. The error in these estimates of natural streamflow is difficult to assess accurately, but it probably is less than 25 percent. (USGS)

  3. Toxocara egg soil contamination and its seroprevalence among public school children in Los Baños, Laguna, Philippines.

    PubMed

    Fajutag, Apryl Joy M; Paller, Vachel Gay V

    2013-07-04

    The soil-transmitted nematode Toxocara sp has little epidemiological information in the Philippines. In this study, we studied the extent of soil contamination with Toxocara eggs and the seroprevalence of Toxocara infection among public school children in Los Baños, Laguna, Philippines. Soil samples were obtained from public schools, backyards, and empty lots in Los Baños to examine for the presence of Toxocara eggs using the modified sucrose flotation technique. Serum samples were obtained from public school children in Los Baños and examined for Toxocara infection using an ELISA test. Of the 200 soil samples, 85 (43%) were positive for Toxocara eggs at a concentration of 1 egg/g of soil. Forty-two percent of soil samples obtained from the public school, 45% of backyard samples, and 40% of empty lot samples were positive. Of the 75 serum samples from children, 37 (49%) were positive for Toxocara infection. There was a positive correlation between Toxocara egg concentration and seroprevalence of Toxocara infection. Results showed a high prevalence of soil contamination and a high seroprevalence of Toxocara infection among children in Los Baños, Laguna, Philippines.

  4. Congener-specific polychlorinated biphenyl patterns in eggs of aquatic birds from the Lower Laguna Madre, Texas

    SciTech Connect

    Mora, M.A.

    1996-06-01

    Eggs from four aquatic bird species nesting in the Lower Laguna Madre, Texas, were collected to determine differences and similarities in the accumulation of congener-specific polychlorinated biphenyls (PCBs) and to evaluate PCB impacts on reproduction. Because of the different toxicities of PCB congeners, it is important to know which congeners contribute most to total PCBs. The predominant PCB congeners were 153, 138, 180, 110, 118, 187, and 92. Collectively, congeners 153, 138, and 180 accounted for 26 to 42% of total PCBs. Congener 153 was the most abundant in Caspian terns (Sterna caspia) and great blue herons (Ardea herodias) and congener 138 was the most abundant in snowy egrets (Egretta thula) and tricolored herons (Egretta tricolor). Principal component analysis indicated a predominance of higher chlorinated biphenyls in Caspian terns and great blue herons and lower chlorinated biphenyls in tricolored herons. Snowy egrets had a predominance of pentachlorobiphenyls. These results suggest that there are differences in PCB congener patterns in closely related species and that these differences are more likely associated with the species` diet rather than metabolism. Total PCBs were significantly greater (p < 0.05) in Caspian terns than in the other species. Overall, PCBs in eggs of birds from the Lower Laguna Madre were below concentrations known to affect bird reproduction.

  5. Congener-specific polychlorinated biphenyl patterns in eggs of aquatic birds from the lower Laguna Madre, Texas

    USGS Publications Warehouse

    Mora, Miguel A.

    1996-01-01

    Eggs from four aquatic bird species nesting in the Lower Laguna Madre, Texas, were collected to determine differences and similarities in the accumulation of congener-specific polychlorinated biphenyls (PCBs) and to evaluate PCB impacts on reproduction. Because of the different toxicities of PCB congeners, it is important to know which congeners contribute most to total PCBs. The predominant PCB congeners were 153, 138, 180, 110, 118, 187, and 92. Collectively, congeners 153, 138, and 180 accounted for 26 to 42% of total PCBs. Congener 153 was the most abundant in Caspian terns (Sterna caspia) and great blue herons (Ardea herodias) and congener 138 was the most abundant in snowy egrets (Egretta thula) and tricolored herons (Egretta tricolor). Principal component analysis indicated a predominance of higher chlorinated biphenyls in Caspian terns and great blue herons and lower chlorinated biphenyls in tricolored herons. Snowy egrets had a predominance of pentachlorobiphenyls. These results suggest that there are differences in PCB congener patterns in closely related species and that these differences are more likely associated with the species' diet rather than metabolism. Total PCBs were significantly greater (p < 0.05) in Caspian terns than in the other species. Overall, PCBs in eggs of birds from the Lower Laguna Madre were below concentrations known to affect bird reproduction.

  6. Distribution and community structure of ichthyoplankton in Laguna Madre seagrass meadows: Potential impact of seagrass species change

    USGS Publications Warehouse

    Tolan, J.M.; Holt, S.A.; Onuf, C.P.

    1997-01-01

    Seasonal ichthyoplankton surveys were made in the lower Laguna Madre, Texas, to compare the relative utilization of various nursery habitats (shoal grass, Halodule wrightii; manatee grass, Syringodium filiforme;, and unvegetated sand bottom) for both estuarine and offshore-spawned larvae. The species composition and abundance of fish larvae were determined for each habitat type at six locations in the bay. Pushnet ichthyoplankton sampling resulted in 296 total collections, yielding 107,463 fishes representing 55 species in 24 families. A broad spectrum of both the biotic and physical habitat parameters were examined to link the dispersion and distribution of both pre-settlement and post-settlement larvae to the utilization of shallow seagrass habitats. Sample sites were grouped by cluster analysis (Ward's minimum variance method) according to the similarity of their fish assemblages and subsequently examined with a multiple discriminant function analysis to identify important environmental variables. Abiotic environmental factors were most influential in defining groups for samples dominated by early larvae, whereas measures of seagrass complexity defined groups dominated by older larvae and juveniles. Juvenile-stage individuals showed clear habitat preference, with the more shallow Halodule wrightii being the habitat of choice, whereas early larvae of most species were widely distributed over all habitats. As a result of the recent shift of dominance from Halodule wrightii to Syringodium filiforme, overall reductions in the quality of nursery habitat for fishes in the lower Laguna Madre are projected.

  7. Mechanical stratigraphy and normal faulting

    NASA Astrophysics Data System (ADS)

    Ferrill, David A.; Morris, Alan P.; McGinnis, Ronald N.; Smart, Kevin J.; Wigginton, Sarah S.; Hill, Nicola J.

    2017-01-01

    Mechanical stratigraphy encompasses the mechanical properties, thicknesses, and interface properties of rock units. Although mechanical stratigraphy often relates directly to lithostratigraphy, lithologic description alone does not adequately describe mechanical behavior. Analyses of normal faults with displacements of millimeters to 10's of kilometers in mechanically layered rocks reveal that mechanical stratigraphy influences nucleation, failure mode, fault geometry, displacement gradient, displacement distribution, fault core and damage zone characteristics, and fault zone deformation processes. The relationship between normal faulting and mechanical stratigraphy can be used either to predict structural style using knowledge of mechanical stratigraphy, or conversely to interpret mechanical stratigraphy based on characterization of the structural style. This review paper explores a range of mechanical stratigraphic controls on normal faulting illustrated by natural and modeled examples.

  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. Selected Hydrologic, Water-Quality, Biological, and Sedimentation Characteristics of Laguna Grande, Fajardo, Puerto Rico, March 2007-February 2009

    USGS Publications Warehouse

    Soler-López, Luis R.; Santos, Carlos R.

    2010-01-01

    Laguna Grande is a 50-hectare lagoon in the municipio of Fajardo, located in the northeasternmost part of Puerto Rico. Hydrologic, water-quality, and biological data were collected in the lagoon between March 2007 and February 2009 to establish baseline conditions and determine the health of Laguna Grande on the basis of preestablished standards. In addition, a core of bottom material was obtained at one site within the lagoon to establish sediment depositional rates. Water-quality properties measured onsite (temperature, pH, dissolved oxygen, specific conductance, and water transparency) varied temporally rather than areally. All physical properties were in compliance with current regulatory standards established for Puerto Rico. Nutrient concentrations were very low and in compliance with current regulatory standards (less than 5.0 and 1.0 milligrams per liter for total nitrogen and total phosphorus, respectively). The average total nitrogen concentration was 0.28 milligram per liter, and the average total phosphorus concentration was 0.02 milligram per liter. Chlorophyll a was the predominant form of photosynthetic pigment in the water. The average chlorophyll-a concentration was 6.2 micrograms per liter. Bottom sediment accumulation rates were determined in sediment cores by modeling the downcore activities of lead-210 and cesium-137. Results indicated a sediment depositional rate of about 0.44 centimeter per year. At this rate of sediment accretion, the lagoon may become a marshland in about 700 to 900 years. About 86 percent of the community primary productivity in Laguna Grande was generated by periphyton, primarily algal mats and seagrasses, and the remaining 14 percent was generated by phytoplankton in the water column. Based on the diel studies the total average net community productivity equaled 5.7 grams of oxygen per cubic meter per day (2.1 grams of carbon per cubic meter per day). Most of this productivity was ascribed to periphyton and macrophytes

  10. 20 CFR 404.507 - Fault.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false Fault. 404.507 Section 404.507 Employees... 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,...

  11. 20 CFR 404.507 - Fault.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 2 2011-04-01 2011-04-01 false Fault. 404.507 Section 404.507 Employees... 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,...

  12. 20 CFR 404.507 - Fault.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 2 2014-04-01 2014-04-01 false Fault. 404.507 Section 404.507 Employees... 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,...

  13. 20 CFR 404.507 - Fault.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 2 2012-04-01 2012-04-01 false Fault. 404.507 Section 404.507 Employees... 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,...

  14. 20 CFR 404.507 - Fault.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 20 Employees' Benefits 2 2013-04-01 2013-04-01 false Fault. 404.507 Section 404.507 Employees... 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,...

  15. 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.

  16. 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?

  17. Fault trees and sequence dependencies

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    One of the frequently cited shortcomings of fault-tree models, their inability to model so-called sequence dependencies, is discussed. Several sources of such sequence dependencies are discussed, and new fault-tree gates to capture this behavior are defined. These complex behaviors can be included in present fault-tree models because they utilize a Markov solution. The utility of the new gates is demonstrated by presenting several models of the fault-tolerant parallel processor, which include both hot and cold spares.

  18. SEISMOLOGY: Watching the Hayward Fault.

    PubMed

    Simpson, R W

    2000-08-18

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

  19. Fault-Tree Compiler Program

    NASA Technical Reports Server (NTRS)

    Butler, Ricky W.; Martensen, Anna L.

    1992-01-01

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

  20. Evaluation Report of the Native American Consortium for Educational and Assistive Technologies for Indian Children Living on the Acoma and Laguna Pueblos.

    ERIC Educational Resources Information Center

    Zastrow, Leona M.

    The New Mexico State Department of Education received a federal grant to provide educational and assistive technology for American Indian children living in the Pueblos of Laguna and Acoma, New Mexico. During the 2-year project, more than 229 assistive technology items were purchased, and some form of assistive technology was provided to 121…

  1. Magnetotelluric Studies of the Laguna del Maule Volcanic Field, Central Chile

    NASA Astrophysics Data System (ADS)

    Cordell, D. R.; Unsworth, M. J.; Diaz, D.; Pavez, M.; Blanco, B.

    2015-12-01

    Geodetic data has shown that the surface of the Laguna del Maule (LdM) volcanic field in central Chile has been moving upwards at rates >20 cm/yr since 2007 over a 200 km2 area. It has been hypothesized that this ground deformation is due to the inflation of a magma body at ~5 km depth beneath the lake (2.8 km b.s.l.). This magma body is a likely source for the large number of rhyolitic eruptions at this location over the last 25 ka. A dense broadband magnetotelluric (MT) array was collected from 2009 to 2015 and included data from a geothermal exploration project. MT phase tensor analysis indicates that the resistivity structure of the region is largely three-dimensional for signals with periods longer than 1 s, which corresponds to depths >5 km. The MT data were inverted using the ModEM inversion algorithm to produce a three-dimensional electrical resistivity model which included topography. Four primary features were identified in the model: 1) A north-south striking, 10 km by 5 km, low-resistivity zone (<5 Ωm) northwest of the inflation centre at a depth of ~5 km (2.8 km b.s.l.) is interpreted as a zone of partial melt which may be supplying material via conduits to account for the observed ground deformation; 2) A shallow low-resistivity feature ~400 m beneath the lake surface (1.8 km a.s.l.) and spatially coincident with the inflation centre is interpreted to be a zone of hydrothermal alteration; 3) A thin, low-resistivity feature to the west of LdM at a depth of ~250 m (2.2 km a.s.l.) is interpreted to be the clay cap of a potential geothermal prospect; 4) A large, low-resistivity zone beneath the San Pedro-Tatara Volcanic Complex to the west of LdM at a depth of ~10 km (8 km b.s.l.) is interpreted to be a zone of partial melt. Further MT data collection is planned for 2016 which will expand the current grid of MT stations to better constrain the lateral extent of the observed features and give greater insight into the dynamics of this restless magma system.

  2. Modelling Temporal and Spatial Variations in Gravimetric Data at Laguna del Maule, Chile

    NASA Astrophysics Data System (ADS)

    Miller, C. A.; Williams-Jones, G.; Currenti, G. M.; Le Mével, H.; Tikoff, B.

    2015-12-01

    Since 2013 we have undertaken annual microgravity and deformation surveys at Laguna del Maule, Chile, to characterise the causes of rapid inflation observed since 2007. The maximum increase in residual gravity is 125 ± 12 microgal between 2013 and 2014, but only 60 ± 15 microgal between 2014 and 2015. The spatial pattern of the gravity anomaly also appears to vary with time. During the 2013-2014 interval, the location of the maximum increase in gravity is near the maximum of the deformation pattern observed by Interferometric Synthetic Aperture Radar (InSAR) between 2007 and 2015 (Le Mével et al. 2015, Geophys. Res. Lett.). During the 2014-2015 interval, the maximum increase in gravity occurs approximately 4 kilometers south west of the center of inflation. Here we present initial source models to explain the observed increases in microgravity. The models are decribed in a framework derived from new spatial Bouguer gravity data, which allows for a better interpretation of time-lapse models. We use a Monte Carlo-type Genetic Algorithm to solve for the optimum source parameters of a range of finite geometry models including spherical, ellipsoidal and sill-like bodies. Finally we compare the finite geometry models to free geometry 3D gravity inversion models. Sources for the 2013-2014 interval locate close to the center of deformation at a depth of approximately 2 to 4 km. Sources for the 2014-2015 interval locate approximately 3 km southwest of the 2013-2014 source, at a similar depth. Positive density contrasts of several hundred kg/m3 are recovered from the source models. The 2013-2014 source locates close to the center of an approximately 15 milliGal Bouguer gravity low while the 2014-2015 source locates close to the edge of the gravity low. Our initial interpretation is that the Bouguer gravity low represents a low density magma body and the 2013-2015 residual microgravity increases represent spatially varying injections of fresh dense magma into that body.

  3. Cross-Cutting Faults

    NASA Technical Reports Server (NTRS)

    2005-01-01

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

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

  4. Fault current limiter

    DOEpatents

    Darmann, Francis Anthony

    2013-10-08

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

  5. Nonlinear Fault Diagnosis,

    DTIC Science & Technology

    1981-05-01

    Systems, New York, Marcel Dekker, (to appear). 3. Desoer , C.A. and S.E. Kuh, Basic Circuit Theory, McGraw-Hill, New York, 1969, pp. 423-425. 130 NONLINEAR...DIAGNOSIS A 7*ssior For 1 MU3 CRA&T IY’IC TAB Ju-st i.cat IC- P.U A: CONTENTS Fault Diagnosis in Electronic Circuits , R. Saeks and R.-w. Liu...Vincentelli and R. Saeks .............. 61 Multitest Diagnosibility of Nonlinear Circuits and Systems, A. Sangiovanni-Vincentelli and R. Saeks

  6. 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

  7. Integrated design of fault reconstruction and fault-tolerant control against actuator faults using learning observers

    NASA Astrophysics Data System (ADS)

    Jia, Qingxian; Chen, Wen; Zhang, Yingchun; Li, Huayi

    2016-12-01

    This paper addresses the problem of integrated fault reconstruction and fault-tolerant control in linear systems subject to actuator faults via learning observers (LOs). A reconfigurable fault-tolerant controller is designed based on the constructed LO to compensate for the influence of actuator faults by stabilising the closed-loop system. An integrated design of the proposed LO and the fault-tolerant controller is explored such that their performance can be simultaneously considered and their coupling problem can be effectively solved. In addition, such an integrated design is formulated in terms of linear matrix inequalities (LMIs) that can be conveniently solved in a unified framework using LMI optimisation technique. At last, simulation studies on a micro-satellite attitude control system are provided to verify the effectiveness of the proposed approach.

  8. AGSM Functional Fault Models for Fault Isolation Project

    NASA Technical Reports Server (NTRS)

    Harp, Janicce Leshay

    2014-01-01

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

  9. Fault Branching and Rupture Directivity

    NASA Astrophysics Data System (ADS)

    Dmowska, R.; Rice, J. R.; Kame, N.

    2002-12-01

    Can the rupture directivity of past earthquakes be inferred from fault geometry? Nakata et al. [J. Geogr., 1998] propose to relate the observed surface branching of fault systems with directivity. Their work assumes that all branches are through acute angles in the direction of rupture propagation. However, in some observed cases rupture paths seem to branch through highly obtuse angles, as if to propagate ``backwards". Field examples of that are as follows: (1) Landers 1992. When crossing from the Johnson Valley to the Homestead Valley (HV) fault via the Kickapoo (Kp) fault, the rupture from Kp progressed not just forward onto the northern stretch of the HV fault, but also backwards, i.e., SSE along the HV [Sowers et al., 1994, Spotila and Sieh, 1995, Zachariasen and Sieh, 1995, Rockwell et al., 2000]. Measurements of surface slip along that backward branch, a prominent feature of 4 km length, show right-lateral slip, decreasing towards the SSE. (2) At a similar crossing from the HV to the Emerson (Em) fault, the rupture progressed backwards along different SSE splays of the Em fault [Zachariasen and Sieh, 1995]. (3). In crossing from the Em to Camp Rock (CR) fault, again, rupture went SSE on the CR fault. (4). Hector Mine 1999. The rupture originated on a buried fault without surface trace [Li et al., 2002; Hauksson et al., 2002] and progressed bilaterally south and north. In the south it met the Lavic Lake (LL) fault and progressed south on it, but also progressed backward, i.e. NNW, along the northern stretch of the LL fault. The angle between the buried fault and the northern LL fault is around -160o, and that NNW stretch extends around 15 km. The field examples with highly obtuse branch angles suggest that there may be no simple correlation between fault geometry and rupture directivity. We propose that an important distinction is whether those obtuse branches actually involved a rupture path which directly turned through the obtuse angle (while continuing

  10. 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

  11. Structure and flow properties of syn-rift border faults: The interplay between fault damage and fault-related chemical alteration (Dombjerg Fault, Wollaston Forland, NE Greenland)

    NASA Astrophysics Data System (ADS)

    Kristensen, Thomas B.; Rotevatn, Atle; Peacock, David C. P.; Henstra, Gijs A.; Midtkandal, Ivar; Grundvåg, Sten-Andreas

    2016-11-01

    Structurally controlled, syn-rift, clastic depocentres are of economic interest as hydrocarbon reservoirs; understanding the structure of their bounding faults is of great relevance, e.g. in the assessment of fault-controlled hydrocarbon retention potential. Here we investigate the structure of the Dombjerg Fault Zone (Wollaston Forland, NE Greenland), a syn-rift border fault that juxtaposes syn-rift deep-water hanging-wall clastics against a footwall of crystalline basement. A series of discrete fault strands characterize the central fault zone, where discrete slip surfaces, fault rock assemblages and extreme fracturing are common. A chemical alteration zone (CAZ) of fault-related calcite cementation envelops the fault and places strong controls on the style of deformation, particularly in the hanging-wall. The hanging-wall damage zone includes faults, joints, veins and, outside the CAZ, disaggregation deformation bands. Footwall deformation includes faults, joints and veins. Our observations suggest that the CAZ formed during early-stage fault slip and imparted a mechanical control on later fault-related deformation. This study thus gives new insights to the structure of an exposed basin-bounding fault and highlights a spatiotemporal interplay between fault damage and chemical alteration, the latter of which is often underreported in fault studies. To better elucidate the structure, evolution and flow properties of faults (outcrop or subsurface), both fault damage and fault-related chemical alteration must be considered.

  12. Availability of ground water in parts of the Acoma and Laguna Indian Reservations, New Mexico

    USGS Publications Warehouse

    Dinwiddie, George A.; Motts, Ward Sundt

    1964-01-01

    The need for additional water has increased in recent years on the Acoma and Laguna Indian Reservations in west-central New Mexico because the population and per capita use of water have increased; the tribes also desire water for light industry, for more modern schools, and to increase their irrigation program. Many wells have been drilled in the area, but most have been disappointing because of small yields and poor chemical quality of the water. The topography in the Acoma and Laguna Indian Reservations is controlled primarily by the regional and local dip of alternating beds of sandstone and shale and by the igneous complex of Mount Taylor. The entrenched alluvial valley along the Rio San Jose, which traverses the area, ranges in width from about 0.4 mile to about 2 miles. The climate is characterized by scant rainfall, which occurs mainly in summer, low relative humidity, and large daily fluctuations of temperature. Most of the surface water enters the area through the Rio San Jose. The average annual streamflow past the gaging station Rio San Jose near Grants, N. Mex. is about 4,000 acre-feet. Tributaries to the Rio San Jose within the area probably contribute about 1,000 acre-feet per year. At the present time, most of the surface water is used for irrigation. Ground water is obtained from consolidated sedimentary rocks that range in age from Triassic to Cretaceous, and from unconsolidated alluvium of Quaternary age. The principal aquifers are the Dakota Sandstone, the Tres Hermanos Sandstone Member of the Mancos Shale, and the alluvium. The Dakota Sandstone yields 5 to 50 gpm (gallons per minute) of water to domestic and stock wells. The Tres Hermanos sandstone Member generally yields 5 to 20 gpm of water to domestic and stock wells. Locally, beds of sandstone in the Chinle and Morrison Formations, the Entrada Sandstone, and the Bluff Sandstone also yield small supplies of water to domestic and stock wells. The alluvium yields from 2 gpm to as much as 150

  13. 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.

  14. 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

  15. SFT: Scalable Fault Tolerance

    SciTech Connect

    Petrini, Fabrizio; Nieplocha, Jarek; Tipparaju, Vinod

    2006-04-15

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

  16. 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.

  17. Naval Weapons Center Active Fault Map Series.

    DTIC Science & Technology

    1987-08-31

    SECURITY CLASSIFICATION OF ’MiS PACE NWC TP 6828 CONTENTS Introduction . . . . . . . . . . . . . . . . . ........... 2 Active Fault Definition ...established along the trace of the Little Take fault zone, within the City of Ridgecrest. ACTIVE FAULT DEFINITION Although it is a commonly used term...34active fault" lacks a pre- cise and universally accepted definition . Most workers, however, accept the following: "Active fault - a fault along

  18. A High-Resolution Reconstruction of Late Holocene Environmental Change from Laguna Ek'Naab, Northern Holmul Region, Peten, Guatemala

    NASA Astrophysics Data System (ADS)

    Anderson, L.; Wahl, D.; Estrada-Belli, F.

    2015-12-01

    Widespread demographic shifts in the southern Maya lowlands at the end of the Classic period have been attributed to environmental change caused by human activity and/or climate variability. Fire was essential to landscape modification and was a primary agent of environmental change associated with prehispanic land use. While several studies have provided insight into the dynamic relationship between natural and anthropogenic drivers of change, defining the specific interplay between natural environmental change, human modification of the environment, and cultural response to changes remains a persistent challenge. Here we present the results of a multi-proxy study that reconstructs fire history, agricultural land use, and environmental change during and after Pre-Columbian Maya settlement. Results are interpreted in the context of settlement history as inferred from archaeological mapping around the study site. Our findings suggest landscape disturbance, as indicated by erosion, local burning, and nearby maize agriculture, was at its peak during the Early Classic period. This disturbance was likely due to large-scale settlement at the nearby site of Witzna'. All proxies indicate a slow decline in disturbance into the Late Classic period, beginning around 1300 cal yr BP. Cival and Chanchich, two proximal site centers to the south of Laguna Ek'Naab, supported their largest populations during the Late Preclassic and Late Classic, with little or no settlement during the Early Classic. The data from Laguna Ek'Naab suggests that Witzna' may have been an important center during the Early Classic. Whether the decreasing environmental degradation after 1240 cal yr BP is do to a decline in local population or changing land use strategies is not discernable based on the data thus far. However, the near complete absence of burning and continued decrease in erosion from 1240-1090 cal yr BP suggests little anthropogenic activity in the area. Burning resumes in the watershed

  19. 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

  20. Synchronized sampling improves fault location

    SciTech Connect

    Kezunovic, M.; Perunicic, B.

    1995-04-01

    Transmission line faults must be located accurately to allow maintenance crews to arrive at the scene and repair the faulted section as soon as possible. Rugged terrain and geographical layout cause some sections of power transmission lines to be difficult to reach. In the past, a variety of fault location algorithms were introduced as either an add-on feature in protective relays or stand-alone implementation in fault locators. In both cases, the measurements of current and voltages were taken at one terminal of a transmission line only. Under such conditions, it may become difficult to determine the fault location accurately, since data from other transmission line ends are required for more precise computations. In the absence of data from the other end, existing algorithms have accuracy problems under several circumstances, such as varying switching and loading conditions, fault infeed from the other end, and random value of fault resistance. Most of the one-end algorithms were based on estimation of voltage and current phasors. The need to estimate phasors introduces additional difficulty in high-speed tripping situations where the algorithms may not be fast enough in determining fault location accurately before the current signals disappear due to the relay operation and breaker opening. This article introduces a unique concept of high-speed fault location that can be implemented either as a simple add-on to the digital fault recorders (DFRs) or as a stand-alone new relaying function. This advanced concept is based on the use of voltage and current samples that are synchronously taken at both ends of a transmission line. This sampling technique can be made readily available in some new DFR designs incorporating receivers for accurate sampling clock synchronization using the satellite Global Positioning System (GPS).

  1. Frictional Heterogeneities Along Carbonate Faults

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  2. Constraint of fault parameters inferred from nonplanar fault modeling

    NASA Astrophysics Data System (ADS)

    Aochi, Hideo; Madariaga, Raul; Fukuyama, Eiichi

    2003-02-01

    We study the distribution of initial stress and frictional parameters for the 28 June 1992 Landers, California, earthquake through dynamic rupture simulation along a nonplanar fault system. We find that observational evidence of large slip distribution near the ground surface requires large nonzero cohesive forces in the depth-dependent friction law. This is the only way that stress can accumulate and be released at shallow depths. We then study the variation of frictional parameters along the strike of the fault. For this purpose we mapped into our segmented fault model the initial stress heterogeneity inverted by Peyrat et al. [2001] using a planar fault model. Simulations with this initial stress field improved the overall fit of the rupture process to that inferred from kinematic inversions, and also improved the fit to the ground motion observed in Southern California. In order to obtain this fit, we had to introduce an additional variations of frictional parameters along the fault. The most important is a weak Kickapoo fault and a strong Johnson Valley fault.

  3. 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.

  4. 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.

  5. 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.

  6. High-resolution paleomagnetic records from Laguna Potrok Aike (Patagonia, Argentina) for the last 16,000 years

    NASA Astrophysics Data System (ADS)

    Gogorza, Claudia S. G.; Irurzun, MaríA. A.; Sinito, Ana M.; Lisé-Pronovost, Agathe; St-Onge, Guillaume; Haberzettl, Torsten; Ohlendorf, Christian; Kastner, Stephanie; Zolitschka, Bernd

    2012-02-01

    Holocene and Late-glacial records documenting variations in direction and intensity of the geomagnetic field during the last 16,000 cal. BP are presented for Southern Patagonia. This continuous high-resolution terrestrial record from Laguna Potrok Aike (51°58'S, 70°23'W) was recovered within the SALSA (South Argentinean Lake Sediment Archives and modeling) project. Mineral magnetic measurements indicate that pseudo single-domain magnetite is the major carrier of the remanence allowing the reliable determination of stable natural remanent magnetization inclinations and declinations from alternating field demagnetization and principal component analysis. Paleomagnetic secular variation records reveal most of the familiar features of declination and inclination that have previously been reported in other records from South Argentina but conspicuous centennial-scale differences are also observed. The results illustrate the potential of paleosecular variations records for dating sedimentary sequences in southern South America.

  7. Characterizing the eolian sediment component in the lacustrine record of Laguna Potrok Aike (southeastern Patagonia)

    NASA Astrophysics Data System (ADS)

    Ohlendorf, C.; Gebhardt, C.

    2013-12-01

    Southern South America with its extended dry areas was one of the major sources for dust in the higher latitudes of the southern hemisphere during the last Glacial, as was deduced from fingerprinting of dust particles found in Antarctic ice cores. The amount of dust that was mobilized is mostly related to strength and latitudinal position of the Southern Hemisphere Westerly Winds (SWW). How exactly SWW shifted between glacial and interglacial times and what consequences such shifts had for ocean and atmospheric circulation changes during the last deglaciation is currently under debate. Laguna Potrok Aike (PTA) as a lake situated in the middle of the source area of dust offers the opportunity to arrive at a better understanding of past SWW changes and their associated consequences for dust transport. For this task, a sediment record of the past ~51 ka is available from a deep drilling campaign (PASADO). From this 106 m long profile, 76 samples representing the different lithologies of the sediment sequence were selected to characterize an eolian sediment component. Prior to sampling of the respective core intervals, magnetic susceptibility was measured and the element composition was determined by XRF-scanning on fresh, undisturbed sediment. After sampling and freeze drying, physical, chemical and mineralogical sediment properties were determined before and after separation of each sample into six grainsize classes for each fraction separately. SEM techniques were used to verify the eolian origin of grains. The aim of this approach is to isolate an exploitable fingerprint of the eolian sediment component in terms of their grain size, physical properties, geochemistry and mineralogy. Thereby, the challenging aspect is that such a fingerprint should be based on high-resolution down-core scanning techniques, so time-consuming techniques such as grain-size measurements by laser detection can be avoided. A first evaluation of the dataset indicates that magnetic

  8. Evolution of Rhyolite at Laguna del Maule, a Rapidly Inflating Volcanic Field in the Southern Andes

    NASA Astrophysics Data System (ADS)

    Andersen, N. L.; Singer, B. S.; Jicha, B. R.; Hildreth, E. W.; Fierstein, J.; Rogers, N. W.

    2012-12-01

    The Laguna del Maule Volcanic Field (LdM) is host to both the foremost example of post-glacial rhyolitic volcanism in the southern Andes and rapid, ongoing crustal deformation. The flare-up of high-silica eruptions was coeval with deglaciation at 24 ka. Rhyolite and rhyodacite domes and coulees totaling 6.5 km3 form a 20 km ring around the central lake basin. This spatial and temporal concentration of rhyolite is unprecedented in the history of the volcanic field. Colinear major and trace element variation suggests these lavas share a common evolutionary history (Hildreth et al., 2010). Moreover, geodetic observations (InSAR & GPS) have identified rapid inflation centered in the western side of the rhyolite dome ring at a rate of 17 cm/year for five years, which has accelerated to 30 cm/yr since April 2012. The best fit to the geodetic data is an expanding magma body located at 5 km depth (Fournier et al., 2010; Le Mevel, 2012). The distribution of high-silica volcanism, most notably geochemically similar high-silica rhyolite lavas erupted 12 km apart of opposite sides of the lake within a few kyr of each other, raises the possibility that the shallow magma intrusion represents only a portion of a larger rhyolitic body, potentially of caldera forming dimensions. We aim to combine petrologic models with a precise geochronology to formulate a model of the evolution of the LdM magma system to its current state. New 40Ar/39Ar age determinations show rhyolitic volcanism beginning at 23 ka with the eruption of the Espejos rhyolite, followed by the Cari Launa Rhyolite at 14.5 ka, two flows of the Barrancas complex at 6.4 and 3.9 ka, and the Divisoria rhyolite at 2.2 ka. In contrast, significant andesitic and dacitic volcanism is largely absent from the central basin of LdM since the early post-glacial period suggesting a coincident basin-wide evolution from andesite to dacite to rhyolite and is consistent with a shallow body of low-density rhyolite blocking the eruption

  9. 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.

  10. 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.

  11. Magma Injection Models to Quantify Reservoir Dynamics at Laguna del Maule Volcanic Field, Chile, between 2007 and 2015.

    NASA Astrophysics Data System (ADS)

    Le Mével, H.; Gregg, P. M.; Feigl, K. L.

    2015-12-01

    Moving beyond the widely used kinematic models for the deformation sources, we present new dynamic models to describe the process of injecting magma into an existing magma reservoir. The 3-dimensional numerical models account for a viscoelastic, gravitationally loaded domain with spatially variable rheological properties. A Newtonian fluid characterized by its viscosity, density, and overpressure (relative to the lithostatic value) intrudes into a viscoelastic solid via a conduit leading to the reservoir. Using the Finite Element Method (FEM), we simultaneously solve the coupled quasi-static elastic and Navier-Stokes governing equations for the solid and the fluid, respectively, using the COMSOL Multiphysics software. The fluid and the solid interact through buoyancy and viscoelastic relaxation, leading to time-dependent deformation. To quantify the "strength" of the source, we define the product of the volume change (in cubic meters) and pressure change (in Pascals) as the "volcanic moment" (in Newton-meters or Joules). This quantity serves as a basis for comparing the calculated displacement fields to analytical solutions. After validating our injection model, we apply it to the ongoing episode of unrest at Laguna del Maule (Chile). Since 2007, the volcanic field there has been deforming at an exceptionally high rate, with vertical velocities up to 200 mm/yr, as measured by GPS and Interferometric Synthetic Aperture Radar (InSAR) between 2013 and 2014, as described recently by Le Mével et al. (2015, Geophys. Res. Lett. http://dx.doi.org/10.1002/2015GL064665). We are modeling the geodetic data to analyze the temporal and spatial evolution of the displacement. These models constrain the mass flux of material into the reservoir and thus its impact on the stress in the crust. Our results contribute to understanding the current unrest episode at Laguna del Maule and to assessing geodetic signals at other active volcanoes.

  12. Recovery of floral and faunal communities after placement of dredged material on seagrasses in Laguna Madre, Texas

    NASA Astrophysics Data System (ADS)

    Sheridan, P.

    2004-03-01

    The objectives of this project were to determine how long alterations in habitat characteristics and use by fishery and forage organisms were detectable at dredged material placement sites in Laguna Madre, Texas. Water, sediment, seagrass, benthos, and nekton characteristics were measured and compared among newly deposited sediments and nearby and distant seagrasses each fall and spring over three years. Over this period, 75% of the estimated total surface area of the original deposits was either re-vegetated by seagrass or dispersed by winds and currents. Differences in water and sediment characteristics among habitat types were mostly detected early in the study. There were signs of steady seagrass re-colonization in the latter half of the study period, and mean seagrass coverage of deposits had reached 48% approximately three years after dredging. Clovergrass Halophila engelmannii was the initial colonist, but shoalgrass Halodule wrightii predominated after about one year. Densities of annelids and non-decapod crustaceans were generally significantly greater in close and distant seagrass habitats than in dredged material habitat, whereas densities of molluscs were not significantly related to habitat type. Nekton (fish and decapod) densities were almost always significantly greater in the two seagrass habitats than in dredged material deposits. Benthos and nekton communities in dredged material deposits were distinct from those in seagrass habitats. Recovery from dredged material placement was nearly complete for water column and sediment components after 1.5 to 3 years, but recovery of seagrasses, benthos, and nekton was predicted to take 4 to 8 years. The current 2 to 5 years dredging cycle virtually insures no time for ecosystem recovery before being disturbed again. The only way to ensure permanent protection of the high primary and secondary productivity of seagrass beds in Laguna Madre from acute and chronic effects of maintenance dredging, while ensuring

  13. Sr Isotopes and Migration of Prairie Mammoths (Mammuthus columbi) from Laguna de las Cruces, San Luis Potosi, Mexico

    NASA Astrophysics Data System (ADS)

    Solis-Pichardo, G.; Perez-Crespo, V.; Schaaf, P. E.; Arroyo-Cabrales, J.

    2011-12-01

    Asserting mobility of ancient humans is a major issue for anthropologists. For more than 25 years, Sr isotopes have been used as a resourceful tracer tool in this context. A comparison of the 87Sr/86Sr ratios found in tooth enamel and in bone is performed to determine if the human skeletal remains belonged to a local or a migrant. Sr in bone approximately reflects the isotopic composition of the geological region where the person lived before death; whereas the Sr isotopic system in tooth enamel is thought to remain as a closed system and thus conserves the isotope ratio acquired during childhood. Sr isotope ratios are obtained through the geologic substrate and its overlying soil, from where an individual got hold of food and water; these ratios are in turn incorporated into the dentition and skeleton during tissue formation. In previous studies from Teotihuacan, Mexico we have shown that a three-step leaching procedure on tooth enamel samples is important to assure that only the biogenic Sr isotope contribution is analyzed. The same Sr isotopic tools can function concerning ancient animal migration patterns. To determine or to discard the mobility of prairie mammoths (Mammuthus columbi) found at Laguna de las Cruces, San Luis Potosi, México the leaching procedure was applied on six molar samples from several fossil remains. The initial hypothesis was to use 87Sr/86Sr values to verify if the mammoth population was a mixture of individuals from various herds and further by comparing their Sr isotopic composition with that of plants and soils, to confirm their geographic origin. The dissimilar Sr results point to two distinct mammoth groups. The mammoth population from Laguna de Cruces was then not a family unit because it was composed by individuals originated from different localities. Only one individual was identified as local. Others could have walked as much as 100 km to find food and water sources.

  14. Why the 2002 Denali fault rupture propagated onto the Totschunda fault: implications for fault branching and seismic hazards

    USGS Publications Warehouse

    Schwartz, David P.; Haeussler, Peter J.; Seitz, Gordon G.; Dawson, Timothy E.

    2012-01-01

    The propagation of the rupture of the Mw7.9 Denali fault earthquake from the central Denali fault onto the Totschunda fault has provided a basis for dynamic models of fault branching in which the angle of the regional or local prestress relative to the orientation of the main fault and branch plays a principal role in determining which fault branch is taken. GeoEarthScope LiDAR and paleoseismic data allow us to map the structure of the Denali-Totschunda fault intersection and evaluate controls of fault branching from a geological perspective. LiDAR data reveal the Denali-Totschunda fault intersection is structurally simple with the two faults directly connected. At the branch point, 227.2 km east of the 2002 epicenter, the 2002 rupture diverges southeast to become the Totschunda fault. We use paleoseismic data to propose that differences in the accumulated strain on each fault segment, which express differences in the elapsed time since the most recent event, was one important control of the branching direction. We suggest that data on event history, slip rate, paleo offsets, fault geometry and structure, and connectivity, especially on high slip rate-short recurrence interval faults, can be used to assess the likelihood of branching and its direction. Analysis of the Denali-Totschunda fault intersection has implications for evaluating the potential for a rupture to propagate across other types of fault intersections and for characterizing sources of future large earthquakes.

  15. 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.

  16. Granular Packings and Fault Zones

    NASA Astrophysics Data System (ADS)

    Åström, J. A.; Herrmann, H. J.; Timonen, J.

    2000-01-01

    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.

  17. 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.

  18. 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."

  19. 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...

  20. 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...

  1. 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...

  2. 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...

  3. 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...

  4. 20 CFR 410.561b - Fault.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

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

  5. 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 §...

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. [Effects of hurricane "Pauline" (1997) on the fauna associated with the plant Eichhornia crassipes in Laguna Coyuca, South Pacific of Mexico].

    PubMed

    Román-Contreras, Ramiro; Rocha-Ramírez, Arturo; Cházaro-Olvera, Sergio

    2008-06-01

    Effects of hurricane "Pauline" (1997) on the fauna associated with the plant Eichhornia crassipes in Laguna Coyuca, South Pacific of Mexico. Reports on the effects of hurricanes on marine and coastal environments often deal with coral reefs, but little is known about their effect on the communities associated with the water hyacinth, Eichhornia crassipes. From January 1997 (pre-hurricane) through April 1998 (post-hurricane) we made montly collections of fauna in E. crassipes roots from Laguna Coyuca, Mexico (17 degrees 00' - 16 degrees 54' N, 99 degrees 58'-100 degrees 05' W). The hurricane affected Coyuca on October 9th, 1997 and caused mortalities of that fauna. During the three subsequent months the absence of E. crassipes and its associated fauna in the study area was evident, but in January 1998, we found a partial reestablishment of E. crassipes and its associated fauna. Four months later, this community was almost back to pre-hurricane levels.

  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

    2015-07-14

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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.).

  20. 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.

  1. Error latency estimation using functional fault modeling

    NASA Technical Reports Server (NTRS)

    Manthani, S. R.; Saxena, N. R.; Robinson, J. P.

    1983-01-01

    A complete modeling of faults at gate level for a fault tolerant computer is both infeasible and uneconomical. Functional fault modeling is an approach where units are characterized at an intermediate level and then combined to determine fault behavior. The applicability of functional fault modeling to the FTMP is studied. Using this model a forecast of error latency is made for some functional blocks. This approach is useful in representing larger sections of the hardware and aids in uncovering system level deficiencies.

  2. Developing Fault Models for Space Mission Software

    NASA Technical Reports Server (NTRS)

    Nikora, Allen P.; Munson, John C.

    2003-01-01

    A viewgraph presentation on the development of fault models for space mission software is shown. The topics include: 1) Goal: Improve Understanding of Technology Fault Generation Process; 2) Required Measurement; 3) Measuring Structural Evolution; 4) Module Attributes; 5) Principal Components of Raw Metrics; 6) The Measurement Process; 7) View of Structural Evolution at the System and Module Level; 8) Identifying and Counting Faults; 9) Fault Enumeration; 10) Modeling Fault Content; 11) Modeling Results; 12) Current and Future Work; and 13) Discussion and Conclusions.

  3. Groundwater flow in a closed basin with a saline shallow lake in a volcanic area: Laguna Tuyajto, northern Chilean Altiplano of the Andes.

    PubMed

    Herrera, Christian; Custodio, Emilio; Chong, Guillermo; Lambán, Luis Javier; Riquelme, Rodrigo; Wilke, Hans; Jódar, Jorge; Urrutia, Javier; Urqueta, Harry; Sarmiento, Alvaro; Gamboa, Carolina; Lictevout, Elisabeth

    2016-01-15

    Laguna Tuyajto is a small, shallow saline water lake in the Andean Altiplano of northern Chile. In the eastern side it is fed by springs that discharge groundwater of the nearby volcanic aquifers. The area is arid: rainfall does not exceed 200mm/year in the rainiest parts. The stable isotopic content of spring water shows that the recharge is originated mainly from winter rain, snow melt, and to a lesser extent from some short and intense sporadic rainfall events. Most of the spring water outflowing in the northern side of Laguna Tuyajto is recharged in the Tuyajto volcano. Most of the spring water in the eastern side and groundwater are recharged at higher elevations, in the rims of the nearby endorheic basins of Pampa Colorada and Pampa Las Tecas to the East. The presence of tritium in some deep wells in Pampa Colorada and Pampa Las Tecas indicates recent recharge. Gas emission in recent volcanoes increase the sulfate content of atmospheric deposition and this is reflected in local groundwater. The chemical composition and concentration of spring waters are the result of meteoric water evapo-concentration, water-rock interaction, and mainly the dissolution of old and buried evaporitic deposits. Groundwater flow is mostly shallow due to a low permeability ignimbrite layer of regional extent, which also hinders brine spreading below and around the lake. High deep temperatures near the recent Tuyajto volcano explain the high dissolved silica contents and the δ(18)O shift to heavier values found in some of the spring waters. Laguna Tuyajto is a terminal lake where salts cumulate, mostly halite, but some brine transfer to the Salar de Aguas Calientes-3 cannot be excluded. The hydrogeological behavior of Laguna Tuyajto constitutes a model to understand the functioning of many other similar basins in other areas in the Andean Altiplano.

  4. Chronologic implications of new Miocene mammals from the Cura-Mallín and Trapa Trapa formations, Laguna del Laja area, south central Chile

    NASA Astrophysics Data System (ADS)

    Flynn, John J.; Charrier, Reynaldo; Croft, Darin A.; Gans, Phillip B.; Herriott, Trystan M.; Wertheim, Jill A.; Wyss, André R.

    2008-12-01

    Recent work in the central Andean Main Range of Chile near Laguna del Laja (˜37.5°S, 71°W) has produced the first mammal fossils for the region. Fossils, locally abundant and well preserved, occur patchily across a wide area southeast of the lake. Mammalian remains are derived from generally strongly folded (kilometer-scale) exposures of the locally ˜1.8 km thick, early to middle Miocene Cura-Mallín Formation; two identifiable specimens have been recovered from the overlying Trapa Trapa Formation as well. Both formations consist primarily of well-stratified (1-5 m thick layers) volcaniclastic and volcanic strata, deposited predominantly in fluviatile systems. The Cura-Mallín Formation is possibly the southern continuation of (or lateral equivalent to) the richly fossiliferous Abanico Formation mapped between ˜32°S and 36°S. Intensive sampling in a series of localities east and south of Laguna del Laja has yielded diverse faunas, in addition to radioisotopically dateable horizons. The new fossil mammal faunas represent as many as six South American Land Mammal "Ages" (SALMAs). Fossils, together with preliminary 40Ar/ 39Ar radioisotopic dates, ranging from ˜9 to 20 Ma across the exposed thickness of the Cura-Mallín Formation and into the overlying Trapa Trapa Formation, provide a robust geochronological framework for middle Cenozoic strata in the Laguna del Laja region. The sequence of directly superposed mammalian assemblages at Laguna del Laja is one of the longest in all of South America, rivaled only by the classic Gran Barranca section of Patagonian Argentina. These data illuminate the geological history of the area and its record of mammalian evolution. The potential to isotopically date these diverse faunas with high precision (error ± 0.5 Ma) presents a rare opportunity to calibrate related portions of the SALMA sequence.

  5. Pesticide and PCB residues in the aquatic ecosystems of Laguna de Terminos, a protected area of the coast of Campeche, Mexico.

    PubMed

    Carvalho, Fernando P; Villeneuve, Jean-Pierre; Cattini, C; Rendón, Jaime; Mota de Oliveira, J

    2009-02-01

    The coastal lagoon system of Laguna de Terminos, Campeche, Mexico, a natural reserve since 1994, was investigated for contamination by agricultural and industrial chemical residues. Water, sediment and biota samples were analyzed for a wide variety of organochlorine and organophosphorus compounds. Chlorpyrifos was detected in water in concentrations up to 72 pgL(-1) and, amongst organochlorine compounds, summation operator PCB were measured averaging 1177 pgL(-1) and summation operator DDT 279 pgL(-1). Residues of chlorinated compounds were present in sediments and in biota with summation operator DDT averaging 190 pg g(-1) and 5876 pg g(-1) in sediment and oysters, respectively. Results show that the more widespread contaminants in the Laguna were residues of chlorinated hydrocarbons, such as DDTs, PCBs, endosulfan, and lindane. Concentrations of residues were not at an alarming level and were even lower than reported for other costal lagoons of the region. Still there is a need to implement control measures on persistent and bioaccumulative compounds that may reach the aquatic system of Laguna de Terminos.

  6. Sulfite-reducing clostridia in the sediment of a high mountain lake (Laguna Grande, Gredos, Spain) as indicators of fecal pollution.

    PubMed

    Robles, S; Rodríguez, J M; Granados, I; Guerrero, M C

    2000-09-01

    We studied the vertical distribution of sulfite-reducing clostridia in the sediment of a Spanish high-mountain lagoon (Laguna Grande de Gredos, central Spain), with optimal sediment characteristics (temperature < 20 degrees C) to maintain spores without growing. This allowed us to assess the original numbers of sulfite-reducing clostridia endospores settled, without postdepositional growing. Sulfite-reducing clostridia are normal inhabitants of the intestinal microbiota of humans and other mammals. These microorganisms may form endospores, which allow the bacteria to survive in almost any habitat, either terrestrial or aquatic, waiting for favorable conditions for growth. Sulfite-reducing clostridia could be suitable indicators of past human pollution because they have a great longevity in natural habitats and they cannot multiply at temperatures below 20 degrees C or in the presence of O2. We found a great increase in the numbers of clostridia (expressed as colony-forming units per gram [CFU/g] of dry weight of sediment) since the 1970s, which reflects the rise of human pressure caused by the practice of outdoor activities. Clostridia CFU/g rose dramatically after the faulty operation of the depuration system of a mountain refuge built close to the lagoon. We compared the vertical distribution of clostridia CFU/g from Laguna Grande sediments with those from a neighbor lagoon (Laguna Cimera), which showed less tourist pressure and no direct disposal of sewage. Finally, we agree with the usefulness of the numbers of sulfite-reducing clostridia as indicators of past pollution.

  7. Identification and dating of indigenous water storage reservoirs along the Rio San José at Laguna Pueblo, western New Mexico, USA

    USGS Publications Warehouse

    Huckleberry, Gary; Ferguson, T.J.; Rittenour, Tammy M.; Banet, Chris; Mahan, Shannon

    2016-01-01

    An investigation into indigenous water storage on the Rio San José in western New Mexico was conducted in support of efforts by the Pueblo of Laguna to adjudicate their water rights. Here we focus on stratigraphy and geochronology of two Native American-constructed reservoirs. One reservoir located near the community of Casa Blanca was formed by a ∼600 m (2000 feet) long stone masonry dam that impounded ∼1.6 × 106 m3 (∼1300 acre-feet) of stored water. Four optically stimulated luminescence (OSL) ages obtained on reservoir deposits indicate that the dam was constructed prior to AD 1825. The other reservoir is located adjacent to Old Laguna Pueblo and contains only a small remnant of its former earthen dam. The depth and distribution of reservoir deposits and a photogrammetric analyses of relict shorelines indicate a storage capacity of ∼6.5 × 106 m3 (∼5300 ac-ft). OSL ages from above and below the base of the reservoir indicate that the reservoir was constructed sometime after AD 1370 but before AD 1750. The results of our investigation are consistent with Laguna oral history and Spanish accounts demonstrating indigenous construction of significant water-storage reservoirs on the Rio San José prior to the late nineteenth century.

  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. Critical fault patterns determination in fault-tolerant computer systems

    NASA Technical Reports Server (NTRS)

    Mccluskey, E. J.; Losq, J.

    1978-01-01

    The method proposed tries to enumerate all the critical fault-patterns (successive occurrences of failures) without analyzing every single possible fault. The conditions for the system to be operating in a given mode can be expressed in terms of the static states. Thus, one can find all the system states that correspond to a given critical mode of operation. The next step consists in analyzing the fault-detection mechanisms, the diagnosis algorithm and the process of switch control. From them, one can find all the possible system configurations that can result from a failure occurrence. Thus, one can list all the characteristics, with respect to detection, diagnosis, and switch control, that failures must have to constitute critical fault-patterns. Such an enumeration of the critical fault-patterns can be directly used to evaluate the overall system tolerance to failures. Present research is focused on how to efficiently make use of these system-level characteristics to enumerate all the failures that verify these characteristics.

  10. Fault branching and rupture directivity

    NASA Astrophysics Data System (ADS)

    Fliss, Sonia; Bhat, Harsha S.; Dmowska, Renata; Rice, James R.

    2005-06-01

    Could the directivity of a complex earthquake be inferred from the ruptured fault branches it created? Typically, branches develop in forward orientation, making acute angles relative to the propagation direction. Direct backward branching of the same style as the main rupture (e.g., both right lateral) is disallowed by the stress field at the rupture front. Here we propose another mechanism of backward branching. In that mechanism, rupture stops along one fault strand, radiates stress to a neighboring strand, nucleates there, and develops bilaterally, generating a backward branch. Such makes diagnosing directivity of a past earthquake difficult without detailed knowledge of the branching process. As a field example, in the Landers 1992 earthquake, rupture stopped at the northern end of the Kickapoo fault, jumped onto the Homestead Valley fault, and developed bilaterally there, NNW to continue the main rupture but also SSE for 4 km forming a backward branch. We develop theoretical principles underlying such rupture transitions, partly from elastostatic stress analysis, and then simulate the Landers example numerically using a two-dimensional elastodynamic boundary integral equation formulation incorporating slip-weakening rupture. This reproduces the proposed backward branching mechanism based on realistic if simplified fault geometries, prestress orientation corresponding to the region, standard lab friction values for peak strength, and fracture energies characteristic of the Landers event. We also show that the seismic S ratio controls the jumpable distance and that curving of a fault toward its compressional side, like locally along the southeastern Homestead Valley fault, induces near-tip increase of compressive normal stress that slows rupture propagation.

  11. Anisotropy of permeability in faulted porous sandstones

    NASA Astrophysics Data System (ADS)

    Farrell, N. J. C.; Healy, D.; Taylor, C. W.

    2014-06-01

    Studies of fault rock permeabilities advance the understanding of fluid migration patterns around faults and contribute to predictions of fault stability. In this study a new model is proposed combining brittle deformation structures formed during faulting, with fluid flow through pores. It assesses the impact of faulting on the permeability anisotropy of porous sandstone, hypothesising that the formation of fault related micro-scale deformation structures will alter the host rock porosity organisation and create new permeability pathways. Core plugs and thin sections were sampled around a normal fault and oriented with respect to the fault plane. Anisotropy of permeability was determined in three orientations to the fault plane at ambient and confining pressures. Results show that permeabilities measured parallel to fault dip were up to 10 times higher than along fault strike permeability. Analysis of corresponding thin sections shows elongate pores oriented at a low angle to the maximum principal palaeo-stress (σ1) and parallel to fault dip, indicating that permeability anisotropy is produced by grain scale deformation mechanisms associated with faulting. Using a soil mechanics 'void cell model' this study shows how elongate pores could be produced in faulted porous sandstone by compaction and reorganisation of grains through shearing and cataclasis.

  12. Fault seal analysis in the North Sea

    SciTech Connect

    Knott, S.D. )

    1993-05-01

    The majority of North Sea structural traps requires that at least one fault be a sealing fault. Over 400 faults from 101 exploration targets and 25 oil and gas fields were analyzed in a regional study of the North Sea. The faults cut clastic successions from a variety of depositional environments (marine, paralic, and nonmarine). The emphasis of the study was on fault-related seals that act as pressure or migration barriers over geologic time. Parameters such as fault strike and throw, reservoir thickness, depth, net-to-gross ratio, porosity, and net sand connectivity were plotted against seal performance to define trends and correlations to predict fault seal characteristics. A correlation appears to exist between fault orientation and sealing, although this is not statistically significant. Sealing is proportional to fault throw norminalized as a fraction of the reservoir thickness. The great majority of faults with throw greater than the thickness of the reservoir interval were sealing faults. The most useful parameters in fault seal prediction are fault displacement, net-to-gross ratio, and net sand connectivity. The conclusions of this study have general applicability to fault seal prediction in exploration, development, and production of hydrocarbons in clastic successions in the North Sea and perhaps other areas as well. 15 refs., 19 figs., 1 tab.

  13. Fault prediction for nonlinear stochastic system with incipient faults based on particle filter and nonlinear regression.

    PubMed

    Ding, Bo; Fang, Huajing

    2017-03-31

    This paper is concerned with the fault prediction for the nonlinear stochastic system with incipient faults. Based on the particle filter and the reasonable assumption about the incipient faults, the modified fault estimation algorithm is proposed, and the system state is estimated simultaneously. According to the modified fault estimation, an intuitive fault detection strategy is introduced. Once each of the incipient fault is detected, the parameters of which are identified by a nonlinear regression method. Then, based on the estimated parameters, the future fault signal can be predicted. Finally, the effectiveness of the proposed method is verified by the simulations of the Three-tank system.

  14. Linking microbial assemblages to paleoenvironmental conditions from the Holocene and Last Glacial Maximum times in Laguna Potrok Aike sediments, Argentina

    NASA Astrophysics Data System (ADS)

    Vuillemin, Aurele; Ariztegui, Daniel; Leavitt, Peter R.; Bunting, Lynda

    2014-05-01

    Laguna Potrok Aike is a closed basin located in the southern hemisphere's mid-latitudes (52°S) where paleoenvironmental conditions were recorded as temporal sedimentary sequences resulting from variations in the regional hydrological regime and geology of the catchment. The interpretation of the limnogeological multiproxy record developed during the ICDP-PASADO project allowed the identification of contrasting time windows associated with the fluctuations of Southern Westerly Winds. In the framework of this project, a 100-m-long core was also dedicated to a detailed geomicrobiological study which aimed at a thorough investigation of the lacustrine subsurface biosphere. Indeed, aquatic sediments do not only record past climatic conditions, but also provide a wide range of ecological niches for microbes. In this context, the influence of environmental features upon microbial development and survival remained still unexplored for the deep lacustrine realm. Therefore, we investigated living microbes throughout the sedimentary sequence using in situ ATP assays and DAPI cell count. These results, compiled with pore water analysis, SEM microscopy of authigenic concretions and methane and fatty acid biogeochemistry, provided evidence for a sustained microbial activity in deep sediments and pinpointed the substantial role of microbial processes in modifying initial organic and mineral fractions. Finally, because the genetic material associated with microorganisms can be preserved in sediments over millennia, we extracted environmental DNA from Laguna Potrok Aike sediments and established 16S rRNA bacterial and archaeal clone libraries to better define the use of DNA-based techniques in reconstructing past environments. We focused on two sedimentary horizons both displaying in situ microbial activity, respectively corresponding to the Holocene and Last Glacial Maximum periods. Sequences recovered from the productive Holocene record revealed a microbial community adapted to

  15. Analysis of the ecosystem structure of Laguna Alvarado, western Gulf of Mexico, by means of a mass balance model

    NASA Astrophysics Data System (ADS)

    Cruz-Escalona, V. H.; Arreguín-Sánchez, F.; Zetina-Rejón, M.

    2007-03-01

    Alvarado is one of the most productive estuary-lagoon systems in the Mexican Gulf of Mexico. It has great economic and ecological importance due to high fisheries productivity and because it serves as a nursery, feeding, and reproduction area for numerous populations of fishes and crustaceans. Because of this, extensive studies have focused on biology, ecology, fisheries (e.g. shrimp, oysters) and other biological components of the system during the last few decades. This study presents a mass-balanced trophic model for Laguna Alvarado to determine it's structure and functional form, and to compare it with similar coastal systems of the Gulf of Mexico and Mexican Pacific coast. The model, based on the software Ecopath with Ecosim, consists of eighteen fish groups, seven invertebrate groups, and one group each of sharks and rays, marine mammals, phytoplankton, sea grasses and detritus. The acceptability of the model is indicated by the pedigree index (0.5) which range from 0 to 1 based on the quality of input data. The highest trophic level was 3.6 for marine mammals and snappers. Total system throughput reached 2680 t km -2 year -1, of which total consumption made up 47%, respiratory flows made up 37% and flows to detritus made up 16%. The total system production was higher than consumption, and net primary production higher than respiration. The mean transfer efficiency was 13.8%. The mean trophic level of the catch was 2.3 and the primary production required to sustain the catch was estimated in 31 t km -2 yr -1. Ecosystem overhead was 2.4 times the ascendancy. Results suggest a balance between primary production and consumption. In contrast with other Mexican coastal lagoons, Laguna Alvarado differs strongly in relation to the primary source of energy; here the primary producers (seagrasses) are more important than detritus pathways. This fact can be interpreted a response to mangrove deforest, overfishing, etc. Future work might include the compilation of

  16. Limnology in El Dorado: some surprising aspects of the regulation of phytoplankton productive capacity in a high-altitude Andean lake (Laguna de Guatavita, Colombia).

    PubMed

    Donato, Jhon; Jimenez, Paola; Reynolds, Colin

    2012-09-01

    High-altitude mountain lakes remain understudied, mostly because of their relative inaccessibility. Laguna de Guatavita, a small, equatorial, high-altitude crater lake in the Eastern Range of the Colombian Andes, was once of high cultural importance to pre-Columban inhabitants, the original location of the legendary El Dorado. We investigated the factors regulating the primary production in Laguna de Guatavita (4degrees58'50" N - 73degrees46'43" W, alt. 2 935m.a.s.l., area: 0.11km2, maximum depth: 30m), during a series of three intensive field campaigns, which were conducted over a year-long period in 2003-2004. In each, standard profiles of temperature, oxygen concentration and light intensity were determined on each of 16-18 consecutive days. Samples were collected and analysed for chlorophyll and for biologically-significant solutes in GF/F-filtered water (NH4+, NO3(-), NO2(-); soluble reactive phosphorus). Primary production was also determined, by oxygen generation, on each day of the campaign. Our results showed that the productive potential of the lake was typically modest (campaign averages of 45-90mg C/m2.h) but that many of the regulating factors were not those anticipated intuitively. The lake is demonstrably meromictic, reminiscent ofkarstic dolines in higher latitudes, its stratification being maintained by solute- concentration gradients. Light penetration is poor, attributable to the turbidity owing to fine calcite and other particulates in suspension. Net primary production in the mixolimnion of Laguna de Guavita is sensitive to day-to-day variations in solar irradiance at the surface. However, deficiencies in nutrient availability, especially nitrogen, also constrain the capacity of the lake to support a phytoplankton. We deduced that Laguna de Guatavita is something of a limnological enigma, atypical of the common anticipation of a "mountain lake". While doubtlessly not unique, comparable descriptions of similar sites elsewhere are sufficiently

  17. PC-based fault finder

    SciTech Connect

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

    1993-07-01

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

  18. Quaternary faults of west Texas

    SciTech Connect

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

    1993-04-01

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

  19. Where's the Hayward Fault? A Green Guide to the Fault

    USGS Publications Warehouse

    Stoffer, Philip W.

    2008-01-01

    This report describes self-guided field trips to one of North America?s most dangerous earthquake faults?the Hayward Fault. Locations were chosen because of their easy access using mass transit and/or their significance relating to the natural and cultural history of the East Bay landscape. This field-trip guidebook was compiled to help commemorate the 140th anniversary of an estimated M 7.0 earthquake that occurred on the Hayward Fault at approximately 7:50 AM, October 21st, 1868. Although many reports and on-line resources have been compiled about the science and engineering associated with earthquakes on the Hayward Fault, this report has been prepared to serve as an outdoor guide to the fault for the interested public and for educators. The first chapter is a general overview of the geologic setting of the fault. This is followed by ten chapters of field trips to selected areas along the fault, or in the vicinity, where landscape, geologic, and man-made features that have relevance to understanding the nature of the fault and its earthquake history can be found. A glossary is provided to define and illustrate scientific term used throughout this guide. A ?green? theme helps conserve resources and promotes use of public transportation, where possible. Although access to all locations described in this guide is possible by car, alternative suggestions are provided. To help conserve paper, this guidebook is available on-line only; however, select pages or chapters (field trips) within this guide can be printed separately to take along on an excursion. The discussions in this paper highlight transportation alternatives to visit selected field trip locations. In some cases, combinations, such as a ride on BART and a bus, can be used instead of automobile transportation. For other locales, bicycles can be an alternative means of transportation. Transportation descriptions on selected pages are intended to help guide fieldtrip planners or participants choose trip

  20. 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

  1. 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.

  2. 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

  3. Growth of faults in crystalline rock

    NASA Astrophysics Data System (ADS)

    Martel, S. J.

    2009-04-01

    The growth of faults depends on the coupled interplay of the distribution of slip, fault geometry, the stress field in the host rock, and deformation of the host rock, which commonly is manifest in secondary fracturing. The distribution of slip along a fault depends highly on its structure, the stress perturbation associated with its interaction with nearby faults, and its strength distribution; mechanical analyses indicate that the first two factors are more influential than the third. Slip distribution data typically are discrete, but commonly are described, either explicitly or implicitly, using continuous interpolation schemes. Where the third derivative of a continuous slip profile is discontinuous, the compatibility conditions of strain are violated, and fracturing and perturbations to fault geometry should occur. Discontinuous third derivatives accompany not only piecewise linear functions, but also functions as seemingly benign as cubic splines. The stress distribution and fracture distribution along a fault depends strongly on how the fault grows. Evidence to date indicates that a fault that nucleates along a pre-existing, nearly planar joint or a dike typically develops secondary fractures only near its tipline when the slip is small relative to the fault length. In contrast, stress concentrations and fractures are predicted where a discontinuous or non-planar fault exhibits steps and bends; field observations bear this prediction out. Secondary fracturing influences how faults grow by creating damage zones and by linking originally discontinuous elements into a single fault zone. Field observations of both strike-slip faults and dip-slip faults show that linked segments usually will not be coplanar; elastic stress analyses indicate that this is an inherent tendency of how three-dimensional faults grow. Advances in the data we collect and in the rigor and sophistication of our analyses seem essential to substantially advance our ability to successfully

  4. Relationship between visual counts and call detection rates of gray whales (Eschrichtius robustus) in Laguna San Ignacio, Mexico.

    PubMed

    Ponce, Diana; Thode, Aaron M; Guerra, Melania; Urbán R, Jorge; Swartz, Steven

    2012-04-01

    Daily acoustic calling rates of Eastern North Pacific (ENP) gray whales were measured on 6 days during 1 mo of their 2008 breeding season in the sheltered coastal lagoon of Laguna San Ignacio in Baja California, Mexico. Visual counts of whales determined that the numbers of single animals in the lower lagoon more than tripled over the observation period. All call types showed production peaks in the early morning and evening with minimum rates generally detected in the early afternoon. For four of the five observation days, the daily number of "S1"-type calls increased roughly as the square of the number of the animals in the lower lagoon during both daytime and nighttime. This relationship persisted when raw call counts were adjusted for variations in background noise level, using a simple propagation law derived from empirical measurements. The one observation day that did not fit the square-law relationship occurred during a week when the group size in the lagoon increased rapidly. These results suggest that passive acoustic monitoring does not measure gray whale group size directly but monitors the number of connections in the social network, which rises as roughly M(2)/2 for a group size M.

  5. [Spatial and temporal variation of the fish community inhabiting the Laguna Grande de Obispo, Gulf of Cariaco, Sucre State, Venezuela].

    PubMed

    de Grado, A A; Bashirullah, A; Prieto, A

    2000-01-01

    The monthly species composition and the spatial and temporal variation of fish community of Laguna Grande de Obispo, Gulf of Canaco, Sucre State, Venezuela were analyzed. The samples were collected using two beach seines of different size from December 1995 to November 1996. A cluster analysis for stations inside the lagoon and time of capture showed 4 major groups, defined principally with ecological parameters of each area. Fishing with large seine in and outside the lagoon showed two large groups which were divided into 10 subgroups in function of station and time, while an inverse analysis of the same sample differentiated into 8 groups of species. based on distribution, dominance, and occurrence. Xenomeianiris brasiliensis, Mugil curema and Eucinostomus argenteus were the most abundant species in both time and space. An analysis of conglomerate on the whole fish community of the sampling period indicated the existence of two groups: i) the first half of the year including December 1995 and October 1996 and ii) the second half of the year. The distribution of fishes in relation to ecological factors is discussed.

  6. Secondary forest succession and tree planting at the Laguna Cartagena and Cabo Rojo wildlife refuges in southwestern Puerto Rico.

    PubMed

    Weaver, Peter L; Schwagerl, Joseph J

    2008-12-01

    Secondary forest succession and tree planting are contributing to the recovery of the Cabo Rojo refuge (Headquarters and Salinas tracts) and Laguna Cartagena refuge (Lagoon and Tinaja tracts) of the Fish and Wildlife Service in southwestern Puerto Rico. About 80 species, mainly natives, have been planted on 44 ha during the past 25 y in an effort to reduce the threat of grass fires and to restore wildlife habitat. A 2007 survey of 9-y-old tree plantings on the Lagoon tract showed satisfactory growth rates for 16 native species. Multiple stems from individual trees at ground level were common. A sampling of secondary forest on the entire 109 ha Tinaja tract disclosed 141 native tree species, or 25% of Puerto Rico's native tree flora, along with 20 exotics. Five tree species made up about 58% of the total basal area, and seven species were island endemics. Between 1998 and 2003, tree numbers and basal area, as well as tree heights and diameter at breast height values (diameter at 1.4 m above the ground), increased on the lower 30 ha of the Tinaja tract. In this area, much of it subject to fires and grazing through 1996, exotic trees made up 25% of the species. Dry forest throughout the tropics is an endangered habitat, and its recovery (i.e., in biomass, structure, and species composition) at Tinaja may exceed 500 y. Future forests, however, will likely contain some exotics.

  7. [The feeding ecology of the endemic fish Girardinichthys multiradiatus (Cyprinidontiformes: Goodeidae) in Lagunas of Zempoala National Park, Mexico].

    PubMed

    Trujillo-Jiménez, Patricia; Monteros Viveros, Efrén Espinosa de los

    2006-12-01

    Girardinichthys multiradiatus, locally known as "mexcalpique", is a small endemic fish of the Lerma river basin. Its presence in lakes (Zempoala) suggests a long-standing connection between these lakes and the river basin. The current range of this species in the Mexico and Toluca valley appears to have been reduced, making this park a refuge for the species. Nevertheless, little is known about its biology. We studied its diet and feeding habits in Acoyotongo Lake, Lagunas de Zempoala National Park (19 degrees 01'30"-19 degrees 06' N, 99 degrees 16'20"-99 degrees 21' W) where seasonal collections were carried out. The gut contents of 97 specimens were identified to the most specific taxonomic category possible and analyzed with numeric and frequency of occurrence methods. The general diet of this species consists of twelve dietary components, eleven of which are of animal origin. Hymenopterans, springtails and chironomids represented the highest percentage of ingestion and preference. G. multiradiatus is as a carnivorous species with entomophagous tendencies.

  8. Truncated Hantavirus Nucleocapsid Proteins for Serotyping Sin Nombre, Andes, and Laguna Negra Hantavirus Infections in Humans and Rodents▿

    PubMed Central

    Koma, Takaaki; Yoshimatsu, Kumiko; Pini, Noemi; Safronetz, David; Taruishi, Midori; Levis, Silvana; Endo, Rika; Shimizu, Kenta; Yasuda, Shumpei P.; Ebihara, Hideki; Feldmann, Heinz; Enria, Delia; Arikawa, Jiro

    2010-01-01

    Sin Nombre virus (SNV), Andes virus (ANDV), and Laguna Negra virus (LANV) have been known as the dominant causative agents of hantavirus pulmonary syndrome (HPS). ANDV and LANV, with different patterns of pathogenicity, exist in a sympatric relationship. Moreover, there is documented evidence of person-to-person transmission of ANDV. Therefore, it is important in clinical medicine and epidemiology to know the serotype of a hantavirus causing infection. Truncated SNV, ANDV, and LANV recombinant nucleocapsid proteins (trNs) missing 99 N-terminal amino acids (trN100) were expressed using a baculovirus system, and their applicability for serotyping SNV, ANDV, and LANV infection by the use of enzyme-linked immunosorbent assays (ELISA) was examined. HPS patient sera and natural-reservoir rodent sera infected with SNV, ANDV, and LANV showed the highest optical density (OD) values for homologous trN100 antigens. Since even patient sera with lower IgM and IgG antibody titers were serotyped, the trN100s are therefore considered useful for serotyping with early-acute-phase sera. In contrast, assays testing whole recombinant nucleocapsid protein antigens of SNV, ANDV, and LANV expressed in Escherichia coli detected homologous and heterologous antibodies equally. These results indicated that a screening ELISA using an E. coli-expressed antigen followed by a serotyping ELISA using trN100s is useful for epidemiological surveillance in regions where two or more hantavirus species cocirculate. PMID:20335425

  9. late Pleistocene and Holocene pollen record from Laguna de las Trancas, northern coastal Santa Cruz County, California

    USGS Publications Warehouse

    Adam, David P.; Byrne, Roger; Luther, Edgar

    1981-01-01

    A 2.1-m core from Laguna de las Trancas, a marsh atop a landslide in northern Santa Cruz County, California, has yielded a pollen record for the period between about 30,000 B. P. and roughly 5000 B. P. Three pollen zones are recognized. The earliest is characterized by high frequencies of pine pollen and is correlated with a mid-Wisconsinan interstade of the mid-continent. The middle zone contains high frequencies of both pine and fir (Abies, probably A. grandis) pollen and is correlated with the last full glacial interval (upper Wisconsinan). The upper zone is dominated by redwood (Sequoia) pollen and represents latest Pleistocene to middle Holocene. The past few thousand years are not represented in the core. The pollen evidence indicates that during the full glacial period the mean annual temperature at the site was about 2°C to 3°C lower than it is today. We attribute this small difference to the stabilizing effect of marine upwelling on the temperature regime in the immediate vicinity of the coast. Precipitation may have been about 20 percent higher as a result of longer winter wet seasons.

  10. Evolution of unrest at Laguna del Maule volcanic field (Chile) from InSAR and GPS measurements, 2003 to 2014

    NASA Astrophysics Data System (ADS)

    Le Mével, Hélène; Feigl, Kurt L.; Córdova, Loreto; DeMets, Charles; Lundgren, Paul

    2015-08-01

    The Laguna del Maule (LdM) volcanic field in the southern volcanic zone of the Chilean Andes exhibits a large volume of rhyolitic material erupted during postglacial times (20-2 ka). Since 2007, LdM has experienced an unrest episode characterized by high rates of deformation. Analysis of new GPS and Interferometric Synthetic Aperture Radar (InSAR) data reveals uplift rates greater than 190 mm/yr between January 2013 and November 2014. The geodetic data are modeled as an inflating sill at depth. The results are used to calculate the temporal evolution of the vertical displacement. The best time function for modeling the InSAR data set is a double exponential model with rates increasing from 2007 through 2010 and decreasing slowly since 2010. We hypothesize that magma intruding into an existing silicic magma reservoir is driving the surface deformation. Modeling historical uplift at Yellowstone, Long Valley, and Three Sisters volcanic fields suggests a common temporal evolution of vertical displacement rates.

  11. An experimental study of memory fault latency

    NASA Technical Reports Server (NTRS)

    Chillarege, Ram; Iyer, Ravi K.

    1989-01-01

    The difficulty with the measurement of fault latency is due to the lack of observability of the fault occurrence and error generation instants in a production environment. The authors describe an experiment, using data from a VAX 11/780 under real workload, to study fault latency in the memory subsystem accurately. Fault latency distributions are generated for stuck-at-zero (s-a-0) and stuck-at-one (s-a-1) permanent fault models. The results show that the mean fault latency of an s-a-0 fault is nearly five times that of the s-a-1 fault. An analysis of variance is performed to quantify the relative influence of different workload measures on the evaluated latency.

  12. 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.

  13. 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.

  14. 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.

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

    NASA Astrophysics Data System (ADS)

    Abe, S.

    2010-12-01

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

  16. Hydraulic Diagnostics and Fault Isolation Test Program.

    DTIC Science & Technology

    1987-02-13

    and Fault Isolation Test Program was to demonstrate and evaluate the practicality of a fault detection and isolation system on an aircraft. The...system capable of fault detection and isolation in a hydraulic subsystem through the use of sensors and a microprocessor (Fig. 1). The microprocessor...DISCUSSION 2.1 DESCRIPTION OF HYDRAULIC SYSTEM SIMULATOR The fault detection and isolation test arrangement consisted of a high pressure, lightweight

  17. 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.

  18. Deep pulverization along active faults ?

    NASA Astrophysics Data System (ADS)

    Doan, M.

    2013-12-01

    Pulverization is a intensive damage observed along some active faults. Rarely found in the field, it has been associated with dynamic damage produced by large earthquakes. Pulverization has been so far only described at the ground surface, consistent with the high frequency tensile loading expected for earthquake occurring along bimaterial faults. However, we discuss here a series of hints suggesting that pulverization is expected also several hundred of meters deep. In the deep well drilled within Nojima fault after the 1995 Kobe earthquake, thin sections reveal non localized damage, with microfractured pervading a sample, but with little shear disturbing the initial microstructure. In the SAFOD borehole drilled near Parkfield, Wiersberg and Erzinger (2008) made gas monitoring while drilling found large amount of H2 gas in the sandstone west to the fault. They attribute this high H2 concentration to mechanochemical origin, in accordance with some example of diffuse microfracturing found in thin sections from cores of SAFOD phase 3 and from geophysical data from logs. High strain rate experiments in both dry (Yuan et al, 2011) and wet samples (Forquin et al, 2010) show that even under confining pressures of several tens of megapascals, diffuse damage similar to pulverization is possible. This could explain the occurrence of pulverization at depth.

  19. 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.

  20. Tsunamis and splay fault dynamics

    USGS Publications Warehouse

    Wendt, J.; Oglesby, D.D.; Geist, E.L.

    2009-01-01

    The geometry of a fault system can have significant effects on tsunami generation, but most tsunami models to date have not investigated the dynamic processes that determine which path rupture will take in a complex fault system. To gain insight into this problem, we use the 3D finite element method to model the dynamics of a plate boundary/splay fault system. We use the resulting ground deformation as a time-dependent boundary condition for a 2D shallow-water hydrodynamic tsunami calculation. We find that if me stress distribution is homogeneous, rupture remains on the plate boundary thrust. When a barrier is introduced along the strike of the plate boundary thrust, rupture propagates to the splay faults, and produces a significantly larger tsunami man in the homogeneous case. The results have implications for the dynamics of megathrust earthquakes, and also suggest mat dynamic earthquake modeling may be a useful tool in tsunami researcn. Copyright 2009 by the American Geophysical Union.

  1. Fault Tolerant Frequent Pattern Mining

    SciTech Connect

    Shohdy, Sameh; Vishnu, Abhinav; Agrawal, Gagan

    2016-12-19

    FP-Growth algorithm is a Frequent Pattern Mining (FPM) algorithm that has been extensively used to study correlations and patterns in large scale datasets. While several researchers have designed distributed memory FP-Growth algorithms, it is pivotal to consider fault tolerant FP-Growth, which can address the increasing fault rates in large scale systems. In this work, we propose a novel parallel, algorithm-level fault-tolerant FP-Growth algorithm. We leverage algorithmic properties and MPI advanced features to guarantee an O(1) space complexity, achieved by using the dataset memory space itself for checkpointing. We also propose a recovery algorithm that can use in-memory and disk-based checkpointing, though in many cases the recovery can be completed without any disk access, and incurring no memory overhead for checkpointing. We evaluate our FT algorithm on a large scale InfiniBand cluster with several large datasets using up to 2K cores. Our evaluation demonstrates excellent efficiency for checkpointing and recovery in comparison to the disk-based approach. We have also observed 20x average speed-up in comparison to Spark, establishing that a well designed algorithm can easily outperform a solution based on a general fault-tolerant programming model.

  2. 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.

  3. Fault current limiters using superconductors

    NASA Astrophysics Data System (ADS)

    Norris, W. T.; Power, A.

    Fault current limiters on power systems are to reduce damage by heating and electromechanical forces, to alleviate duty on switchgear used to clear the fault, and to mitigate disturbance to unfaulted parts of the system. A basic scheme involves a super-resistor which is a superconductor being driven to high resistance when fault current flows either when current is high during a cycle of a.c. or, if the temperature of the superconductive material rises, for the full cycle. Current may be commuted from superconductor to an impedance in parallel, thus reducing the energy dispersed at low temperature and saving refrigeration. In a super-shorted transformer the ambient temperature primary carries the power system current; the superconductive secondary goes to a resistive condition when excessive currents flow in the primary. A super-transformer has the advantage of not needing current leads from high temperature to low temperature; it behaves as a parallel super-resistor and inductor. The supertransductor with a superconductive d.c. bias winding is large and has small effect on the rate of fall of current at current zero; it does little to alleviate duty on switchgear but does reduce heating and electromechanical forces. It is fully active after a fault has been cleared. Other schemes depend on rapid recooling of the superconductor to achieve this.

  4. 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...

  5. 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...

  6. 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...

  7. 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...

  8. 20 CFR 255.11 - Fault.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

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

  9. 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...

  10. 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...

  11. 5 CFR 845.302 - Fault.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

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

  12. 40 CFR 258.13 - Fault areas.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Fault areas. 258.13 Section 258.13... SOLID WASTE LANDFILLS Location Restrictions § 258.13 Fault areas. (a) New MSWLF units and lateral expansions shall not be located within 200 feet (60 meters) of a fault that has had displacement in...

  13. 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...

  14. 40 CFR 258.13 - Fault areas.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Fault areas. 258.13 Section 258.13... SOLID WASTE LANDFILLS Location Restrictions § 258.13 Fault areas. (a) New MSWLF units and lateral expansions shall not be located within 200 feet (60 meters) of a fault that has had displacement in...

  15. 5 CFR 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...

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. 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...

  1. 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...

  2. 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...

  3. 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...

  4. Measurement and application of fault latency

    NASA Technical Reports Server (NTRS)

    Shin, K. G.; Lee, Y.-H.

    1986-01-01

    The time interval between the occurrence of a fault and the detection of the error caused by the fault is divided by the generation of that error into two parts: fault latency and error latency. Since the moment of error generation is not directly observable, all related works in the literature have dealt with only the sum of fault and error latencies, thereby making the analysis of their separate effects impossible. To remedy this deficiency, (1) a new methodology for indirectly measuring fault latency is presented; the distribution of fault latency is derived from the methodology; and (3) the knowledge of fault latency is applied to the analysis of two important examples. The proposed methodology has been implemented for measuring fault latency in the Fault-Tolerant Multiprocessor (FTMP) at the NASA Airlab. The experimental results show wide variations in the mean fault latencies of different function circuits within FTMP. Also, the measured distributions of fault latency are shown to have monotone hazard rates. Consequently, Gamma and Weibull distributions are selected for the least-squares fit as the distribution of fault latency.

  5. 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).

  6. 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.

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

    USGS Publications Warehouse

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

    2010-01-01

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

  8. 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.…

  9. 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.

  10. Fault Diagnosis in HVAC Chillers

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

  11. Fault tolerant 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.

  12. 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.

  13. 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.

  14. 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.

  15. Hydrologic, water-quality, and biological assessment of Laguna de las Salinas, Ponce, Puerto Rico, January 2003-September 2004

    USGS Publications Warehouse

    Soler-López, Luis R.; Gómez-Gómez, Fernando; Rodríguez-Martínez, Jesús

    2005-01-01

    The Laguna de Las Salinas is a shallow, 35-hectare, hypersaline lagoon (depth less than 1 meter) in the municipio of Ponce, located on the southern coastal plain of Puerto Rico. Hydrologic, water-quality, and biological data in the lagoon were collected between January 2003 and September 2004 to establish baseline conditions. During the study period, rainfall was about 1,130 millimeters, with much of the rain recorded during three distinct intense events. The lagoon is connected to the sea by a shallow, narrow channel. Subtle tidal changes, combined with low rainfall and high evaporation rates, kept the lagoon at salinities above that of the sea throughout most of the study. Water-quality properties measured on-site (temperature, pH, dissolved oxygen, specific conductance, and Secchi disk transparency) exhibited temporal rather than spatial variations and distribution. Although all physical parameters were in compliance with current regulatory standards for Puerto Rico, hyperthermic and hypoxic conditions were recorded during isolated occasions. Nutrient concentrations were relatively low and in compliance with current regulatory standards (less than 5.0 and 1.0 milligrams per liter for total nitrogen and total phosphorus, respectively). The average total nitrogen concentration was 1.9 milligrams per liter and the average total phosphorus concentration was 0.4 milligram per liter. Total organic carbon concentrations ranged from 12.0 to 19.0 milligrams per liter. Chlorophyll a was the predominant form of photosynthetic pigment in the water. The average chlorophyll a concentration was 13.4 micrograms per liter. Chlorophyll b was detected (detection limits 0.10 microgram per liter) only twice during the study. About 90 percent of the primary productivity in the Laguna de Las Salinas was generated by periphyton such as algal mats and macrophytes such as seagrasses. Of the average net productivity of 13.6 grams of oxygen per cubic meter per day derived from the diel

  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. 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.

  18. Fault diagnosis for magnetic bearing systems

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

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

  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. 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.

  1. 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.

  2. Naval weapons center active fault map series

    NASA Astrophysics Data System (ADS)

    Roquemore, G. R.; Zellmer, J. T.

    1987-08-01

    The NWC Active Fault Map Series shows the locations of active faults and features indicative of active faulting within much of Indian Wells Valley and portions of the Randsburg Wash/Mojave B test range areas of the Naval Weapons Center. Map annotations are used extensively to identify criteria employed in identifying the fault offsets, and to present other valuable data. All of the mapped faults show evidence of having moved during about the last 12,500 years or represent geologically young faults that occur within seismic gaps. Only faults that offset the surface or show other evidence of surface deformation were mapped. A portion of the City of Ridgecrest is recommended as being a Seismic Hazard Special Studies Zone in which detailed earthquake hazard studies should be required.

  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 sensor fault diagnosis for dynamic processes.

    PubMed

    Li, Cheng-Chih; Jeng, Jyh-Cheng

    2010-10-01

    Modern industrial plants are usually large scaled and contain a great amount of sensors. Sensor fault diagnosis is crucial and necessary to process safety and optimal operation. This paper proposes a systematic approach to detect, isolate and identify multiple sensor faults for multivariate dynamic systems. The current work first defines deviation vectors for sensor observations, and further defines and derives the basic sensor fault matrix (BSFM), consisting of the normalized basic fault vectors, by several different methods. By projecting a process deviation vector to the space spanned by BSFM, this research uses a vector with the resulted weights on each direction for multiple sensor fault diagnosis. This study also proposes a novel monitoring index and derives corresponding sensor fault detectability. The study also utilizes that vector to isolate and identify multiple sensor faults, and discusses the isolatability and identifiability. Simulation examples and comparison with two conventional PCA-based contribution plots are presented to demonstrate the effectiveness of the proposed methodology.

  5. Method to identify wells that yield water that will be replaced by water from the Colorado River downstream from Laguna Dam in Arizona and California

    USGS Publications Warehouse

    Owen-Joyce, Sandra J.; Wilson, Richard P.; Carpenter, Michael C.; Fink, James B.

    2000-01-01

    Accounting for the use of Colorado River water is required by the U.S. Supreme Court decree, 1964, Arizona v. California. Water pumped from wells on the flood plain and from certain wells on alluvial slopes outside the flood plain is presumed to be river water and is accounted for as Colorado River water. The accounting-surface method developed for the area upstream from Laguna Dam was modified for use downstream from Laguna Dam to identify wells outside the flood plain of the lower Colorado River that yield water that will be replaced by water from the river. Use of the same method provides a uniform criterion of identification for all users pumping water from wells by determining if the static water-level elevation in the well is above or below the elevation of the accounting surface. Wells that have a static water-level elevation equal to or below the accounting surface are presumed to yield water that will be replaced by water from the Colorado River. Wells that have a static water-level elevation above the accounting surface are presumed to yield river water stored above river level. The method is based on the concept of a river aquifer and an accounting surface within the river aquifer. The river aquifer consists of permeable sediments and sedimentary rocks that are hydraulically connected to the Colorado River so that water can move between the river and the aquifer in response to withdrawal of water from the aquifer or differences in water-level elevations between the river and the aquifer. The subsurface limit of the river aquifer is the nearly impermeable bedrock of the bottom and sides of the basins that underlie the Yuma area and adjacent valleys. The accounting surface represents the elevation and slope of the unconfined static water table in the river aquifer outside the flood plain of the Colorado River that would exist if the river were the only source of water to the river aquifer. The accounting surface was generated by using water

  6. Silica Lubrication in Faults (Invited)

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  7. 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

  8. Microbial Diversity in Sediment Ecosystems (Evaporites Domes, Microbial Mats, and Crusts) of Hypersaline Laguna Tebenquiche, Salar de Atacama, Chile.

    PubMed

    Fernandez, Ana B; Rasuk, Maria C; Visscher, Pieter T; Contreras, Manuel; Novoa, Fernando; Poire, Daniel G; Patterson, Molly M; Ventosa, Antonio; Farias, Maria E

    2016-01-01

    We combined nucleic acid-based molecular methods, biogeochemical measurements, and physicochemical characteristics to investigate microbial sedimentary ecosystems of Laguna Tebenquiche, Atacama Desert, Chile. Molecular diversity, and biogeochemistry of hypersaline microbial mats, rhizome-associated concretions, and an endoevaporite were compared with: The V4 hypervariable region of the 16S rRNA gene was amplified by pyrosequencing to analyze the total microbial diversity (i.e., bacteria and archaea) in bulk samples, and in addition, in detail on a millimeter scale in one microbial mat and in one evaporite. Archaea were more abundant than bacteria. Euryarchaeota was one of the most abundant phyla in all samples, and particularly dominant (97% of total diversity) in the most lithified ecosystem, the evaporite. Most of the euryarchaeal OTUs could be assigned to the class Halobacteria or anaerobic and methanogenic archaea. Planctomycetes potentially also play a key role in mats and rhizome-associated concretions, notably the aerobic organoheterotroph members of the class Phycisphaerae. In addition to cyanobacteria, members of Chromatiales and possibly the candidate family Chlorotrichaceae contributed to photosynthetic carbon fixation. Other abundant uncultured taxa such as the candidate division MSBL1, the uncultured MBGB, and the phylum Acetothermia potentially play an important metabolic role in these ecosystems. Lithifying microbial mats contained calcium carbonate precipitates, whereas endoevoporites consisted of gypsum, and halite. Biogeochemical measurements revealed that based on depth profiles of O2 and sulfide, metabolic activities were much higher in the non-lithifying mat (peaking in the least lithified systems) than in lithifying mats with the lowest activity in endoevaporites. This trend in decreasing microbial activity reflects the increase in salinity, which may play an important role in the biodiversity.

  9. Holocene History of the Chocó Rain Forest from Laguna Piusbi, Southern Pacific Lowlands of Colombia

    NASA Astrophysics Data System (ADS)

    Behling, Hermann; Hooghiemstra, Henry; Negret, Alvaro José

    1998-11-01

    A high-resolution pollen record from a 5-m-long sediment core from the closed-lake basin Laguna Piusbi in the southern Colombian Pacific lowlands of Chocó, dated by 11 AMS 14C dates that range from ca. 7670 to 220 14C yr B.P., represents the first Holocene record from the Chocó rain forest area. The interval between 7600 and 6100 14C yr B.P. (500-265 cm), composed of sandy clays that accumulated during the initial phase of lake formation, is almost barren of pollen. Fungal spores and the presence of herbs and disturbance taxa suggest the basin was at least temporarily inundated and the vegetation was open. The closed lake basin might have formed during an earthquake, probably about 4400 14C yr B.P. From the interval of about 6000 14C yr B.P. onwards, 200 different pollen and spore types were identified in the core, illustrating a diverse floristic composition of the local rain forest. Main taxa are Moraceae/Urticaceae, Cecropia,Melastomataceae/Combretaceae, Acalypha, Alchornea,Fabaceae, Mimosa, Piper, Protium, Sloanea, Euterpe/Geonoma, Socratea,and Wettinia.Little change took place during that time interval. Compared to the pollen records from the rain forests of the Colombian Amazon basin and adjacent savannas, the Chocó rain forest ecosystem has been very stable during the late Holocene. Paleoindians probably lived there at least since 3460 14C yr B.P. Evidence of agricultural activity, shown by cultivation of Zea maissurrounding the lake, spans the last 1710 yr. Past and present very moist climate and little human influence are important factors in maintaining the stable ecosystem and high biodiversity of the Chocó rain forest.

  10. [Some attributes of community structure of fishes in Laguna Grande de Obispo, Golfo Cariaco, Sucre State, Venezuela].

    PubMed

    De Grado, A A; Bashirullah, A

    2001-01-01

    Species composition, relative abundance, diversity and community structure of fishes were studied from monthly sampling during December 1995 to November 1996 in the Laguna Grande de Obispo, Gulf of Cariaco, Sucre State, Venezuela. Sampling were realised in 3 stations inside the lagoon with a small beach seine and the other 4 stations with a large beach seine. Seventy four species belonging to 33 families and 68 genera were identified of which 8 species dominated, constituting 90.43% of total catch. Mugil curema, Xenomelaniris brasiliensis, Opistonema oglinum, Atherinomorus stipes and Anchoa hepsetus were present in high abundance in the biomass. M. curema dominated the catch with large seine while X. brasiliensis, M. curema and Eucinostomus argenteus dominated the catch with small seine. Species diversity (H') ranged from 2.968-4.607 bits/ind and species richness of Margalef from 2.752-7.464. An inverse analysis realized on catches by small seine and based on nodal constancy and fidelity allowed to define a pattern of spatial distribution of 9 groups containing 1 to 11 species on the basis their abundance, frequency of appearance and ecological characteristics of each area. An analysis of correlation showed that the salinity, dissolved O2 and precipitation did not show any significant correlation with the ecological parameters studied but existed significant correlation with average surface water temperature (p < 0.05), number of species (S), individuals (N), diversity (H') and species richness (D). The positive correlation was found with surface temperature but no relationship with relative dominance (D1 and D2). The CPUE in biomass did not show any significant association with temperature.

  11. Microbial Diversity in Sediment Ecosystems (Evaporites Domes, Microbial Mats, and Crusts) of Hypersaline Laguna Tebenquiche, Salar de Atacama, Chile

    PubMed Central

    Fernandez, Ana B.; Rasuk, Maria C.; Visscher, Pieter T.; Contreras, Manuel; Novoa, Fernando; Poire, Daniel G.; Patterson, Molly M.; Ventosa, Antonio; Farias, Maria E.

    2016-01-01

    We combined nucleic acid-based molecular methods, biogeochemical measurements, and physicochemical characteristics to investigate microbial sedimentary ecosystems of Laguna Tebenquiche, Atacama Desert, Chile. Molecular diversity, and biogeochemistry of hypersaline microbial mats, rhizome-associated concretions, and an endoevaporite were compared with: The V4 hypervariable region of the 16S rRNA gene was amplified by pyrosequencing to analyze the total microbial diversity (i.e., bacteria and archaea) in bulk samples, and in addition, in detail on a millimeter scale in one microbial mat and in one evaporite. Archaea were more abundant than bacteria. Euryarchaeota was one of the most abundant phyla in all samples, and particularly dominant (97% of total diversity) in the most lithified ecosystem, the evaporite. Most of the euryarchaeal OTUs could be assigned to the class Halobacteria or anaerobic and methanogenic archaea. Planctomycetes potentially also play a key role in mats and rhizome-associated concretions, notably the aerobic organoheterotroph members of the class Phycisphaerae. In addition to cyanobacteria, members of Chromatiales and possibly the candidate family Chlorotrichaceae contributed to photosynthetic carbon fixation. Other abundant uncultured taxa such as the candidate division MSBL1, the uncultured MBGB, and the phylum Acetothermia potentially play an important metabolic role in these ecosystems. Lithifying microbial mats contained calcium carbonate precipitates, whereas endoevoporites consisted of gypsum, and halite. Biogeochemical measurements revealed that based on depth profiles of O2 and sulfide, metabolic activities were much higher in the non-lithifying mat (peaking in the least lithified systems) than in lithifying mats with the lowest activity in endoevaporites. This trend in decreasing microbial activity reflects the increase in salinity, which may play an important role in the biodiversity. PMID:27597845

  12. Waterbirds and human-related threats to their conservation in Laguna Cuyutlán, Colima, México.

    PubMed

    Mellink, Eric; Riojas-López, Mónica

    2009-01-01

    Laguna Cuyutlán, the only large wetland in a span of 1,150 km along the Pacific coast of Mexico, has been neglected as to its importance for waterbird conservation. At least 25 waterbird species nest there, with some of their colonies being very relevant, and at least 61 waterbird species use the lagoon during their non-breeding season. This lagoon has been subject to several structural modifications, including levees and artificial channels which connect it to the sea, while water supply from continental sources has diminished, although its role has not been assessed yet. Salt extraction and artisanal fishery, the main economic activities, do not seem to pose a threat to waterbirds. Among potential threats to this acquatic ecosystem, are the raw sewage discharges that exist near urban areas, and pesticides from the surrounding agricultural lands might reach the lagoon. Seemingly, the most serious threat comes from waterway development in connection with a re-gasification plant to be built, and planned future port expansion, which could potentially increase water levels and alter important habitats for nesting and foraging. We recommend that: the area be declared an Important Bird Area; the development of the re-gasification plant and future port includes a levee to prevent alterations in water level in the remaining sections of the lagoon; supply of exogenous chemicals and waste products be prevented and monitored; alleged benefits from water interchange between the lagoon and the sea through artificial channels should be re-evaluated; and the role of fresh water supplies to the lagoon should be paid attention to.

  13. Reconstructing paleoenvironmental conditions during the past 50 ka from the biogeochemical record of Laguna Potrok Aike, southern Patagonia

    NASA Astrophysics Data System (ADS)

    Hahn, A.; Rosén, P.; Kliem, P.; Ohlendorf, C.; Zolitschka, B.

    2011-12-01

    Total organic carbon (TOC), total inorganic carbon (TIC) and biogenic silica (BSi) assessed by Fourier transform infrared spectroscopy (FTIRS) are used to reconstruct the environmental history during the past 50kyrs in high resolution from Laguna Potrok Aike. During the Holocene warmer conditions lead to an increased productivity reflected in higher TOC and BSi contents. Calcite precipitation initiated around 9 ka cal. BP probably due to supersaturation induced by lake level lowering. It is assumed that prior to this time period sediments are carbonate-free because high lake-level conditions prevailed. During the Glacial, increased runoff linked to permafrost, precipitation related to stronger cyclonic activity and reduced evaporation have caused higher lake levels. Moreover, during cold glacial conditions lake productivity was low and organic matter mainly of algal or cyanobacterial origin as indicated by generally low TOC and C/N values. During interstadials, such as the Antarctic A-events and the Younger Dryas, TOC contents appear to rise. The glacial C/N ratios and their correlation with TOC concentrations indicate that aquatic moss blooms probably induce these increases in TOC. Aquatic mosses grow if surface water temperatures rise due to warmer climatic conditions and/or development of a lake water stratification. The latter may occur if wind speeds are low and melt water inflow caused higher density gradients. Prevailing permafrost thawing during warmer periods could lead to considerable rises of lake levels, which would contribute to the preservation of organic material. This may explain why higher C/N and TOC values occur at the end of Antarctic A-events. For the uppermost 25 m, the BSi profile shows a high correlation with the TOC profile. In deeper horizons, however, there are indications that the BSi/TOC ratio increased. This part of the record is dominated by mass movement events, which may have supplied nutrients and thus triggered diatom blooms.

  14. From Fault Seal to Fault Leak: Effect of Mechanical Stratigraphy on the Evolution of Transport Processes in Fault Zones (Invited)

    NASA Astrophysics Data System (ADS)

    Urai, J. L.; Schmatz, J.; van Gent, H. W.; Abe, S.; Holland, M.

    2009-12-01

    Predictions of the transport properties of faults in layered sequences are usually based on geometry and lithology of the faulted sequence. Mechanical properties and fault resealing processes are used much less frequently. Based on laboratory, field and numerical studies we present a model, which takes into account these additional factors. When the ratio of rock strength and in-situ mean effective stress is high enough to allow hybrid failure, dilatant fracture networks will form in that part of the sequence which meets this condition, dramatically increasing permeability along the fault, with possibility of along-fault fluid flow and vertical transport of fine grained sediment to form clay gouge in dilatant jogs. A key parameter here is the 3D connectivity of the dilatant fracture network. In systems where fracturing is non-dilatant and the mechanical contrast between the layers is small, the fault zones are relatively simple in structure, with complexity concentrated in relay zones between segments at different scales. With increasing mechanical contrast between the layers (and the presence of preexisting fractures), patterns of localization and fault zone structure become increasingly complex. Mechanical mixing in the fault gouge is a major process especially when one of the lithologies is highly permeable. Reworking of wall rocks composed of hard claystones produces a low-permeability clay gouge in critical state. Circulating supersaturated fluids in the fault zone produce vein networks, which reseal the fault zone, typically in a cyclic fashion.

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

    USGS Publications Warehouse

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

    2004-01-01

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

  16. Fault linkage: Three-dimensional mechanical interaction between echelon normal faults

    NASA Astrophysics Data System (ADS)

    Crider, Juliet G.; Pollard, David D.

    1998-10-01

    Field observations of two overlapping normal faults and associated deformation document features common to many normal-fault relay zones: a topographic ramp between the fault segments, tapering slip on the faults as they enter the overlap zone, and associated fracturing, especially at the top of the ramp. These observations motivate numerical modeling of the development of a relay zone. A three-dimensional boundary element method numerical model, using simple fault-plane geometries, material properties, and boundary conditions, reproduces the principal characteristics of the observed fault scarps. The model, with overlapping, semicircular fault segments under orthogonal extension, produces a region of high Coulomb shear stress in the relay zone that would favor fault linkage at the center to upper relay ramp. If the fault height is increased, the magnitude of the stresses in the relay zone increases, but the position of the anticipated linkage does not change. The amount of fault overlap changes the magnitude of the Coulomb stress in the relay zone: the greatest potential for fault linkage occurs with the closest underlapping fault tips. Ultimately, the mechanical interaction between segments of a developing normal-fault system promote the development of connected, zigzagging fault scarps.

  17. 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

  18. Fault trees and imperfect coverage

    NASA Technical Reports Server (NTRS)

    Dugan, Joanne B.

    1989-01-01

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

  19. Fault Injection Techniques and Tools

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

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

  20. 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.

  1. Folding above faults, Rocky Mountains

    SciTech Connect

    McConnell, D.A. . Dept. of Geology)

    1992-01-01

    Asymmetric folds formed above basement faults can be observed throughout the Rocky Mountains. Several previous interpretations of the folding process made the implicit assumption that one or both fold hinges migrated or rolled'' through the steep forelimb of the fold as the structure evolved (rolling hinge model). Results of mapping in the Bighorn and Seminoe Mountains, WY, and Sangre de Cristo Range, CO, do not support this hypothesis. An alternative interpretation is presented in which fold hinges remained fixed in position during folding (fixed hinge model). Mapped folds share common characteristics: (1) axial traces of the folds intersect faults at or near the basement/cover interface, and diverge from faults upsection; (2) fold hinges are narrow and interlimb angles cluster around 80--100[degree] regardless of fold location; (3) fold shape is typically angular, despite published cross sections that show concentric folds; and, (4) beds within the folds show thickening and/or thinning, most commonly adjacent to fold hinges. The rolling hinge model requires that rocks in the fold forelimbs bend through narrow fold hinges as deformation progressed. Examination of massive, competent rock units such as the Ord. Bighorn Dolomite, Miss. Madison Limestone, and, Penn. Tensleep Sandstone reveals no evidence of the extensive internal deformation that would be expected if hinges rolled through rocks of the forelimb. The hinges of some folds (e.g. Golf Creek anticline, Bighorn Mountains) are offset by secondary faults, effectively preventing the passage of rocks from backlimb to forelimb. The fixed hinge model proposes that the fold hinges were defined early in fold evolution, and beds were progressively rotated and steepened as the structure grew.

  2. Fault Tolerance of Neural Networks

    DTIC Science & Technology

    1994-07-01

    Systematic Ap - proach, Proc. Government Microcircuit Application Conf. (GOMAC), San Diego, Nov. 1986. [10] D.E.Goldberg, Genetic Algorithms in Search...s l m n ttempt to develop fault tolerant neural networks. The lows. Given a well-trained network, we first eliminate temp todevlopfaut tlernt eurl ...both ap - proaches, and this resulted in very slight improve- ments over the addition/deletion procedure. 103 Fisher’s Iris data in average case Fisher’s

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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

  8. 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.

  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. 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.

  11. Seismological Constraints on Fault Plane Curvature

    NASA Astrophysics Data System (ADS)

    Reynolds, K.

    2015-12-01

    The down-dip geometry of seismically active normal faults is not well known. Many examples of normal faults with down-dip curvature exist, such as listric faults revealed in cross-section or in seismic reflection data, or the exposed domes of core complexes. However, it is not understood: (1) whether curved faults fail in earthquakes, and (2) if those faults have generated earthquakes, is the curvature a primary feature of the rupture or due to later modification of the plane? Even if an event is surface-rupturing, because of the limited depth-extent over which observations can be made, it is difficult to reliably constrain the change in dip with depth (if any) and therefore the fault curvature. Despite the uncertainty in seismogenic normal fault geometries, published slip inversions most commonly use planar fault models. We investigate the seismological constraints on normal fault geometry using a forward-modelling approach and present a seismological technique for determining down-dip geometry. We demonstrate that complexity in the shape of teleseismic body waveforms may be used to investigate the presence of down-dip fault plane curvature. We have applied this method to a catalogue of continental and oceanic normal faulting events. Synthetic models demonstrate that the shapes of SH waveforms at along-strike stations are particularly sensitive to fault plane geometry. It is therefore important to consider the azimuthal station coverage before modelling an event. We find that none of the data require significant down-dip curvature, although the modelling results for some events remain ambiguous. In some cases we can constrain that the down-dip fault geometry is within 20° of planar.

  12. Just add water and the Colorado River still reaches the sea.

    PubMed

    Glenn, Edward P; Flessa, Karl W; Cohen, Michael J; Nagler, Pamela L; Rowell, Kirsten; Zamora-Arroyo, Francisco

    2007-07-01

    A recent article in Environmental Management by All argued that flood flows in North America's Colorado River do not reach the Gulf of California because they are captured and evaporated in Laguna Salada, a below sea-level lakebed near the mouth of the river. We refute this hypothesis by showing that (1) due to its limited area, the Laguna Salada could have evaporated less than 10% of the flood flows that have occurred since 1989; (2) low flow volumes preferentially flow to the Gulf rather than Laguna Salada; (3) All's method for detecting water surface area in the Laguna Salada appears to be flawed because Landsat Thematic Mapper images of the lakebed show it to be dry when All's analyses said it was flooded; (4) direct measurements of salinity at the mouth of the river and in the Upper Gulf of California during flood flows in 1993 and 1998 confirm that flood waters reach the sea; and (5) stable oxygen isotope signatures in clam shells and fish otoliths recorded the dilution of seawater with fresh water during the 1993 and 1998 flows. Furthermore, All's conclusion that freshwater flows do not benefit the ecology of the marine zone is incorrect because the peer-reviewed literature shows that postlarval larval shrimp populations increase during floods, and the subsequent year's shrimp harvest increases. Furthermore, freshwater flows increase the nursery area for Gulf corvina (Cynoscion othonopterus), an important commercial fish that requires estuarine habitats with salinities in the range of 26-38 per thousand during its natal stages. Although flood flows are now much diminished compared to the pre-dam era, they are still important to the remnant wetland and riparian habitats of the Colorado River delta and to organisms in the intertidal and marine zone. Only a small fraction of the flood flows are evaporated in Laguna Salada.

  13. 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

  14. 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

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

    NASA Astrophysics Data System (ADS)

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

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

  16. Primary and secondary faulting in the Najd fault system, Kingdom of Saudi Arabia

    USGS Publications Warehouse

    Moore, John McMahon

    1979-01-01

    The Najd fault system is a major transcurrent (strike-slip) fault system of Proterozoic age in the Arabian Shield. The system is a braided complex of parallel and curved en echelon faults. Complex arrays of secondary structures including strike-slip, oblique-slip, thrust, and normal faults, together with folds and dike swarms, are associated with some major faults, particularly near their terminations. The secondary structures indicate that compressional and extensional and dilational conditions existed synchronously in different parts of the fault zone. The outcrop traces of faults and syntectonic dikes have been used to interpret the configuration of principal compressive stresses during formation of parts of the secondary fracture systems. Second-order deformation was a series of separate events in a complex episodic faulting history. Comparison with model studies indicates that master faults extended in length in stages and periodically developed arrays of secondary structures. Propagation of the major faults took place along splay trajectories, which inter-connected to form a subparallel sheeted and braided zone. Interpretation of the aeromagnetic maps indicates that the Najd system is broader at depth than the outcropping fault complex, and that more continuous structures underlie arrays of faults at surface. The fault pattern is mechanically explicable in terms of simple shear between rigid blocks beneath the exposed structures.

  17. The Energetics of Gravity Driven Faulting

    NASA Astrophysics Data System (ADS)

    Barrows, L.

    2007-12-01

    Faulting can result from either of two different mechanisms. These involve fundamentally different energetics. In displacement-bounded faulting, locked-in elastic strain energy is transformed into seismic waves plus work done in the fault zone. Elastic rebound is an example of displacement-bounded faulting. In force-driven faulting, the forces that create the stress on the fault supply work or energy to the faulting process. Half of this energy is transformed into seismic waves plus work done in the fault zone and half goes into an increase in locked-in elastic strain. In displacement-bounded faulting the locked-in elastic strain drives slip on the fault. In force-driven faulting it stops slip on the fault. Tectonic stress is reasonably attributed to gravity acting on topography and the Earth's lateral density variations. This includes the thermal convection that ultimately drives plate tectonics. The gravity collapse seismic mechanism assumes the fault fails and slips in direct response to the gravitational tectonic stress. Gravity collapse is an example of force-driven faulting. In the simplest case, energy that is released from the gravitational potential of the topography and internal stress-causing density variations is equally split between the seismic waves plus work done in the fault zone and the increase in locked-in elastic strain. The release of gravitational potential energy requires a change in the Earth's density distribution. Gravitational body forces are solely dependent on density so a change in the density distribution requires a change in the body forces. This implies the existence of volumetric body-force displacements. The volumetric body-force displacements are in addition to displacements generated by slip on the fault. They must exist if gravity participates in the energetics of the faulting process. From the perspective of gravitational tectonics, the gravity collapse mechanism is direct and simple. The related mechanics are a little more

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

    USGS Publications Warehouse

    Sharp, R.V.

    1989-01-01

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

  19. Fault Model Development for Fault Tolerant VLSI Design

    DTIC Science & Technology

    1988-05-01

    it minimizes the number of bridging 5 % -W V,. Pi’%A faults but because of the ease with which the layout principles can be automated . This implies a...diffusion over a significant portion. Thus, it turns out .. 4 that the layout chosen on the basis of easy automation is also efficient in terms of...34, Proo. 24th ACM/IEEE . Design Automation Conference, June 1987, pp 244-250. 106 ii * . .A 16. [Reddy,19861 Sudhakar M. Reddy and Madhukar M. Reddy

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

    NASA Technical Reports Server (NTRS)

    Vouk, Mladen A.; Mcallister, David F.

    1990-01-01

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

  1. The 1992 Landers earthquake and surface faulting

    USGS Publications Warehouse

    Rymer, Michael J.

    1992-01-01

    Faulting associated with the June 28, 992, earthquake near Landers, California, broke the surface of the ground over a length of more than 70 km, the longest surface rupture in the United States since the great San Francisco quake of 1906. the strongest shaking associated with this magnitude 7.6 (MS) earthquake, the largest in the contiguous 48 states in the last 40 years, occurred in a sparsely populated sections of the Mojave Desert more than 200 km east of Los Angeles. the earthquake began with a sudden slip on the Johnson Valley fault about 10 km southwest of Landers. The initial fault movement probably occurred at a depth of less than 10 km. Surface faulting then propagated over 70 km to the north and northeast. The faulting linked preexisting faults-some previously known and mapped and others previously unknown-into a complex, coherent rupture zone. 

  2. New results in fault latency modelling

    NASA Technical Reports Server (NTRS)

    Mcgough, J. G.; Swern, F. L.; Bavuso, S.

    1983-01-01

    Studies carried out by McGough and Swern (1981, 1983) are summarized. In these studies, an avionics processor was simulated and a series of fault injection experiments was carried out to determine the degree of fault latency in a redundant flight control system that employed comparison monitoring as the exclusive means of failure detection. A determination was also made of the fault coverage of a typical self-test program. The summary presented stresses that a self-test program should be designed to capitalize on the hardware mechanization of the processor. If this is not done, subtests tend to repeatedly exercise the same hardware components while neglecting to exercise a substantial proportion of the remainder. It is also pointed out that fault latency is relatively independent of both the length and instruction mix of a program. A significant difference is found in fault coverage assessed using pin-level and gate-level fault models.

  3. A new intelligent hierarchical fault diagnosis system

    SciTech Connect

    Huang, Y.C.; Huang, C.L.; Yang, H.T.

    1997-02-01

    As a part of a substation-level decision support system, a new intelligent Hierarchical Fault Diagnosis System for on-line fault diagnosis is presented in this paper. The proposed diagnosis system divides the fault diagnosis process into two phases. Using time-stamped information of relays and breakers, phase 1 identifies the possible fault sections through the Group Method of Data Handling (GMDH) networks, and phase 2 recognizes the types and detailed situations of the faults identified in phase 1 by using a fast bit-operation logical inference mechanism. The diagnosis system has been practically verified by testing on a typical Taiwan power secondary transmission system. Test results show that rapid and accurate diagnosis can be obtained with flexibility and portability for fault diagnosis purpose of diverse substations.

  4. Fault-tolerant dynamic task graph scheduling

    SciTech Connect

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

    2014-11-16

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

  5. 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.

  6. In-circuit fault injector user's guide

    NASA Technical Reports Server (NTRS)

    Padilla, Peter A.

    1987-01-01

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

  7. Performance Analysis on Fault Tolerant Control System

    NASA Technical Reports Server (NTRS)

    Shin, Jong-Yeob; Belcastro, Christine

    2005-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

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

  9. Approximate active fault detection and control

    NASA Astrophysics Data System (ADS)

    Škach, Jan; Punčochář, Ivo; Šimandl, Miroslav

    2014-12-01

    This paper deals with approximate active fault detection and control for nonlinear discrete-time stochastic systems over an infinite time horizon. Multiple model framework is used to represent fault-free and finitely many faulty models. An imperfect state information problem is reformulated using a hyper-state and dynamic programming is applied to solve the problem numerically. The proposed active fault detector and controller is illustrated in a numerical example of an air handling unit.

  10. 31 CFR 29.522 - Fault.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

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

  11. 31 CFR 29.522 - Fault.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

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

  12. 31 CFR 29.522 - Fault.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

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

  13. 31 CFR 29.522 - Fault.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

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

  14. 31 CFR 29.522 - Fault.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

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

  15. Hydrogen Embrittlement And Stacking-Fault Energies

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  16. A Millennial Length High-Resolution Pollen, Charcoal, Diatom and Stable Isotope Record from Laguna San Carlos, Panama

    NASA Astrophysics Data System (ADS)

    St Jacques, J. M.; Escobar, J.; Velez, M.; Correa-Metrio, A.; Curtis, J. H.

    2014-12-01

    We report here on preliminary results from Laguna San Carlos, (8o 37' 32.44''N, 80o 03' 04.24'' W) a small, shallow (8.3 m) volcanic lake from west-central Panama, a relatively unstudied Pacific coast region that is an important location for paleo-ENSO studies. The circular lake is a closed basin lake with a gradually sloping shoreline located within a caldera. The 300 cm core was taken in 2 m of water during March 2010. The core bottom was resting upon basement granitic rock with feldspar phenocrystals. The chronology is based upon five radiocarbon dates from terrestrial plant and wood remains. Pollen and charcoal were sampled at 10 cm resolution, diatoms at 5 cm and stable isotopes at 1 cm. The pollen profile shows four distinct terrestrial vegetation units. During the Medieval Climate Anomaly (MCA), from AD 880-1485, the vegetation was sparse with high amounts of grass, Asteraceae and charcoal suggestive of grasslands with high rates of natural disturbance, including fire. With the onset of the Little Ice Age (LIA), during AD 1485-1570, the vegetation transitioned into an open dry forest characterized by Myrica and Anacardium with high seasonality in precipitation. At AD 1570, the climate became wetter as shown by the pollen typical of a moist tropical forest. This lasted until AD 1720 when a period of greater human disturbance began (as shown by increased sedimentation rates), with primary forest taxa cohabiting with grasses and secondary taxa. The first maize pollen appeared at ~AD 1700. The diatom record is dominated by a single eutrophic species, Fragilaria crotonensis; however from AD 880-1150 minor taxa such as Aulacoseira spp., indicative of increased turbulence appeared, supporting the pollen record of open canopy vegetation at this time. The sedimentary carbon/nitrogen ratio (C/N) shows that the majority of the organic remains in the lake have always come from the surrounding basin. MTM spectral analysis of percent Fragilaria crotonensis, percent carbon

  17. Crustal deformation and magmatic processes at Laguna del Maule volcanic field (Chile): Geodetic measurements and numerical models

    NASA Astrophysics Data System (ADS)

    Le Mével, Hélène

    The Laguna del Maule (LdM) volcanic field in Chile is an exceptional example of postglacial rhyolitic volcanism in the Southern Volcanic Zone of the Andes. Since 2007, LdM has experienced an unrest episode characterized by high rates of deformation measured by interferometric analysis of synthetic aperture radar (SAR) images acquired between 2007 and 2016, and data from the Global Positioning System (GPS) recorded since 2012 at five stations. The inflating region includes most of the 16--km-by--14--km ring of rhyolitic domes and coulees. The fastest-moving GPS station (MAU2) has a velocity vector of [[special character omited]72 +/- 4, 19 +/- 1, 194 +/- 3] mm/yr between 2012 and 2016 for the eastward, northward, and upward components, respectively. First, we model the InSAR observations assuming a rectangular dislocation in a half space with uniform elastic properties. The best time function for modeling the InSAR data set is a double exponential model with rates increasing from 2007 through 2010 and decreasing slowly since 2011. Modeling of historical uplift at Yellowstone, Long Valley, and Three Sisters volcanic fields suggests a common temporal evolution of vertical displacement rates. We hypothesize that magma intruding into an existing silicic magma reservoir is driving the surface deformation and present a new dynamic model to describe this process. A Newtonian fluid characterized by its viscosity, density, and pressure flows through a vertical conduit, intruding into a reservoir embedded in an elastic domain and leading to time-dependent surface deformation. Using a grid-search optimization, we minimize the misfit to the InSAR displacement data by varying the three parameters governing the analytical solution: the characteristic timescale tauP for magma propagation, the injection pressure, and the inflection time when the acceleration switches from positive to negative. For a spheroid with semi-major axis a = 6200 m, semi-minor axis c = 100 m, located at a

  18. Rapid uplift during 2007-2012 at Laguna del Maule volcanic field, Andean Southern Volcanic Zone, Chile

    NASA Astrophysics Data System (ADS)

    Le Mevel, H.; Feigl, K.; Ali, T.; Cordova V., M. L.; DeMets, C.; Singer, B. S.

    2012-12-01

    The Laguna del Maule (LdM) volcanic field includes an unusual concentration of post-glacial rhyolitic lava coulees and domes, dated between 24 to 2 thousand years old that cover more than 100 square kilometers and erupted from 24 vents that encircle a 20-km-diameter lake basin on the range crest. The recent concentration of rhyolite is unparalleled in the Southern Volcanic Zone of the Andes. Moreover, the western portion of the LdM volcanic field has experienced rapid uplift since 2007, leading to questions about the current configuration of the magmatic system and processes that drive the ongoing inflation. We aim to quantify the active deformation of the LdM volcanic field and its evolution with time. To do so, we use interferometric synthetic aperture radar (InSAR) data acquired by three satellite missions: Envisat in 2003 and 2004, ALOS between 2007 and 2010, and TerraSAR-X in 2012. An interferogram spanning March 2003 to February 2004 "shows no deformation" (Fournier et al., 2010). From 2007 through 2012, however, the shortening of the satellite-to-ground distance revealed a range change rate of greater than 200 mm/yr along the radar line of sight. The deformation includes a circular area 20 km in diameter centered on the western portion of the circle of young rhyolite domes. To analyze the InSAR results, we employ the General Inversion for Phase Technique (GIPhT; Feigl and Thurber, 2009; Ali and Feigl, 2012). We have considered several hypotheses to interpret this deformation. Artefacts such as orbital errors, atmospheric perturbations or topographic contribution cannot account for the observed signal. We also reject the hypothesis of uplift due to gravitational unloading of the crust based on our modeling of independently measured lake level variations over the observed time interval. We thus attribute the deformation to the intrusion of magma into the upper crust below the southwest region of the LdM volcanic field. The best fit to the InSAR data is

  19. An Aspect-Oriented Approach to Assessing Fault Tolerance

    DTIC Science & Technology

    2014-10-01

    this paper, we present a fault tolerance assessment framework designed for distributed systems that provides automated injection of faults without... fault tolerance techniques work. Ensuring fault tolerance in military communication systems is particularly important due to the inevitability of...changes to client or server code and automated assessment of whether the injected faults are tolerated. The framework applies aspect-oriented

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

    NASA Technical Reports Server (NTRS)

    Ellis, Erik L.; Butler, Ricky W.

    1987-01-01

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

  1. Applications of Fault Detection in Vibrating Structures

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  2. Chip level simulation of fault tolerant computers

    NASA Technical Reports Server (NTRS)

    Armstrong, J. R.

    1983-01-01

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

  3. Mantle fault zone beneath Kilauea Volcano, Hawaii.

    PubMed

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

    2003-04-18

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

  4. Block rotations, fault domains and crustal deformation

    NASA Technical Reports Server (NTRS)

    Nur, A.; Ron, H.

    1987-01-01

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

  5. Active faults in southeastern Harris County, Texas

    NASA Technical Reports Server (NTRS)

    Clanton, U. S.; Amsbury, D. L.

    1975-01-01

    Aerial color infrared photography was used to investigate active faults in a complex graben in southeastern Harris County, Tex. The graben extends east-west across an oil field and an interstate highway through Ellington Air Force Base (EAFB), into the Clear Lake oil field and on to LaPorte, Tex. It was shown that the fault pattern at EAFB indicates an appreciable horizontal component associated with the failure of buildings, streets, and runways. Another fault system appears to control the shoreline configuration of Clear Lake, with some of the faults associated with tectonic movements and the production of oil and gas, but many related to extensive ground water withdrawal.

  6. Faults Discovery By Using Mined Data

    NASA Technical Reports Server (NTRS)

    Lee, Charles

    2005-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Vouk, Mladen A.; Mcallister, David F.

    1993-01-01

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

  8. Acoustic fault injection tool (AFIT)

    NASA Astrophysics Data System (ADS)

    Schoess, Jeffrey N.

    1999-05-01

    On September 18, 1997, Honeywell Technology Center (HTC) successfully completed a three-week flight test of its rotor acoustic monitoring system (RAMS) at Patuxent River Flight Test Center. This flight test was the culmination of an ambitious 38-month proof-of-concept effort directed at demonstrating the feasibility of detecting crack propagation in helicopter rotor components. The program was funded as part of the U.S. Navy's Air Vehicle Diagnostic Systems (AVDS) program. Reductions in Navy maintenance budgets and available personnel have dictated the need to transition from time-based to 'condition-based' maintenance. Achieving this will require new enabling diagnostic technologies. The application of acoustic emission for the early detection of helicopter rotor head dynamic component faults has proven the feasibility of the technology. The flight-test results demonstrated that stress-wave acoustic emission technology can detect signals equivalent to small fatigue cracks in rotor head components and can do so across the rotating articulated rotor head joints and in the presence of other background acoustic noise generated during flight operation. During the RAMS flight test, 12 test flights were flown from which 25 Gbyte of digital acoustic data and about 15 hours of analog flight data recorder (FDR) data were collected from the eight on-rotor acoustic sensors. The focus of this paper is to describe the CH-46 flight-test configuration and present design details about a new innovative machinery diagnostic technology called acoustic fault injection. This technology involves the injection of acoustic sound into machinery to assess health and characterize operational status. The paper will also address the development of the Acoustic Fault Injection Tool (AFIT), which was successfully demonstrated during the CH-46 flight tests.

  9. Fault rheology beyond frictional melting

    PubMed Central

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

    2015-01-01

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

  10. Fault rheology beyond frictional melting.

    PubMed

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

    2015-07-28

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

  11. Detection of CMOS bridging faults using minimal stuck-at fault test sets

    NASA Technical Reports Server (NTRS)

    Ijaz, Nabeel; Frenzel, James F.

    1993-01-01

    The performance of minimal stuck-at fault test sets at detecting bridging faults are evaluated. New functional models of circuit primitives are presented which allow accurate representation of bridging faults under switch-level simulation. The effectiveness of the patterns is evaluated using both voltage and current testing.

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

    NASA Technical Reports Server (NTRS)

    Bergman, Eric A.; Solomon, Sean C.

    1988-01-01

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

  13. Pseudo-fault signal assisted EMD for fault detection and isolation in rotating machines

    NASA Astrophysics Data System (ADS)

    Singh, Dheeraj Sharan; Zhao, Qing

    2016-12-01

    This paper presents a novel data driven technique for the detection and isolation of faults, which generate impacts in a rotating equipment. The technique is built upon the principles of empirical mode decomposition (EMD), envelope analysis and pseudo-fault signal for fault separation. Firstly, the most dominant intrinsic mode function (IMF) is identified using EMD of a raw signal, which contains all the necessary information about the faults. The envelope of this IMF is often modulated with multiple vibration sources and noise. A second level decomposition is performed by applying pseudo-fault signal (PFS) assisted EMD on the envelope. A pseudo-fault signal is constructed based on the known fault characteristic frequency of the particular machine. The objective of using external (pseudo-fault) signal is to isolate different fault frequencies, present in the envelope . The pseudo-fault signal serves dual purposes: (i) it solves the mode mixing problem inherent in EMD, (ii) it isolates and quantifies a particular fault frequency component. The proposed technique is suitable for real-time implementation, which has also been validated on simulated fault and experimental data corresponding to a bearing and a gear-box set-up, respectively.

  14. A novel KFCM based fault diagnosis method for unknown faults in satellite reaction wheels.

    PubMed

    Hu, Di; Sarosh, Ali; Dong, Yun-Feng

    2012-03-01

    Reaction wheels are one of the most critical components of the satellite attitude control system, therefore correct diagnosis of their faults is quintessential for efficient operation of these spacecraft. The known faults in any of the subsystems are often diagnosed by supervised learning algorithms, however, this method fails to work correctly when a new or unknown fault occurs. In such cases an unsupervised learning algorithm becomes essential for obtaining the correct diagnosis. Kernel Fuzzy C-Means (KFCM) is one of the unsupervised algorithms, although it has its own limitations; however in this paper a novel method has been proposed for conditioning of KFCM method (C-KFCM) so that it can be effectively used for fault diagnosis of both known and unknown faults as in satellite reaction wheels. The C-KFCM approach involves determination of exact class centers from the data of known faults, in this way discrete number of fault classes are determined at the start. Similarity parameters are derived and determined for each of the fault data point. Thereafter depending on the similarity threshold each data point is issued with a class label. The high similarity points fall into one of the 'known-fault' classes while the low similarity points are labeled as 'unknown-faults'. Simulation results show that as compared to the supervised algorithm such as neural network, the C-KFCM method can effectively cluster historical fault data (as in reaction wheels) and diagnose the faults to an accuracy of more than 91%.

  15. 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.

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

    NASA Technical Reports Server (NTRS)

    Joshi, Suresh M.

    2012-01-01

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

  17. a case of casing deformation and fault slip for the active fault drilling

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    Active fault is normally defined as a fault with displacement or seismic activity during the geologically recent period (in the last 10,000 years, USGS). Here, we refer the active fault to the fault that is under the post-seismic stress modification or recovery. Micro-seismic, fault slip would happen during the recovery of the active faults. It is possible that the drilling through this active fault, such as the Wenchuan Fault Scientific Drilling(WFSD), will be accompanied with some possible wellbore instability and casing deformation, which is noteworthy for the fault scientific drilling. This presentation gives a field case of the Wenchuan earthquake. The great Wenchuan earthquake happened on May 12, 2008. An oilfield is 400km apart from the epicenter and 260km from the main fault. Many wells were drilled or are under drilling. Some are drilled through the active fault and a few tectonic active phenomenons were observed. For instance, a drill pipe was cut off in the well which was just drilled through the fault. We concluded that this is due to the fault slip,if not, so thick wall pipe cannot be cut off. At the same time, a mass of well casings of the oilfield deformed during the great Wenchuan Earthquake. The analysis of the casing deformation characteristic, formation structure, seismicity, tectonic stress variation suggest that the casing deformation is closely related to the Wenchuan Earthquake. It is the tectonic stress variation that induces seismic activities, fault slip, salt/gypsum creep speedup, and deformation inconsistent between stratums. Additional earthquake dynamic loads were exerted on the casing and caused its deformation. Active fault scientific drilling has become an important tool to understand earthquake mechanism and physics. The casing deformation and wellbore instability is not only a consequence of the earthquake but also an indicator of stress modification and fault activity. It is noteworthy that tectonic stress variation and fault

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

    USGS Publications Warehouse

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

    2001-01-01

    In May 1997, the US Geological Survey (USGS) and the University of Southern California (USC) acquired high-resolution seismic reflection and refraction images on the grounds of the Wadsworth Veterans Administration Hospital (WVAH) in the city of Los Angeles (Fig. 1a,b). The objective of the seismic survey was to better understand the near-surface geometry and faulting characteristics of the Santa Monica fault zone. In this report, we present seismic images, an interpretation of those images, and a comparison of our results with results from studies by Dolan and Pratt (1997), Pratt et al. (1998) and Gibbs et al. (2000). The Santa Monica fault is one of the several northeast-southwest-trending, north-dipping, reverse faults that extend through the Los Angeles metropolitan area (Fig. 1a). Through much of area, the Santa Monica fault trends subparallel to the Hollywood fault, but the two faults apparently join into a single fault zone to the southwest and to the northeast (Dolan et al., 1995). The Santa Monica and Hollywood faults may be part of a larger fault system that extends from the Pacific Ocean to the Transverse Ranges. Crook et al. (1983) refer to this fault system as the Malibu Coast-Santa Monica-Raymond-Cucamonga fault system. They suggest that these faults have not formed a contiguous zone since the Pleistocene and conclude that each of the faults should be treated as a separate fault with respect to seismic hazards. However, Dolan et al. (1995) suggest that the Hollywood and Santa Monica faults are capable of generating Mw 6.8 and Mw 7.0 earthquakes, respectively. Thus, regardless of whether the overall fault system is connected and capable of rupturing in one event, individually, each of the faults present a sizable earthquake hazard to the Los Angeles metropolitan area. If, however, these faults are connected, and they were to rupture along a continuous fault rupture, the resulting hazard would be even greater. Although the Santa Monica fault represents

  19. Fault Management Techniques in Human Spaceflight Operations

    NASA Technical Reports Server (NTRS)

    O'Hagan, Brian; Crocker, Alan

    2006-01-01

    This paper discusses human spaceflight fault management operations. Fault detection and response capabilities available in current US human spaceflight programs Space Shuttle and International Space Station are described while emphasizing system design impacts on operational techniques and constraints. Preflight and inflight processes along with products used to anticipate, mitigate and respond to failures are introduced. Examples of operational products used to support failure responses are presented. Possible improvements in the state of the art, as well as prioritization and success criteria for their implementation are proposed. This paper describes how the architecture of a command and control system impacts operations in areas such as the required fault response times, automated vs. manual fault responses, use of workarounds, etc. The architecture includes the use of redundancy at the system and software function level, software capabilities, use of intelligent or autonomous systems, number and severity of software defects, etc. This in turn drives which Caution and Warning (C&W) events should be annunciated, C&W event classification, operator display designs, crew training, flight control team training, and procedure development. Other factors impacting operations are the complexity of a system, skills needed to understand and operate a system, and the use of commonality vs. optimized solutions for software and responses. Fault detection, annunciation, safing responses, and recovery capabilities are explored using real examples to uncover underlying philosophies and constraints. These factors directly impact operations in that the crew and flight control team need to understand what happened, why it happened, what the system is doing, and what, if any, corrective actions they need to perform. If a fault results in multiple C&W events, or if several faults occur simultaneously, the root cause(s) of the fault(s), as well as their vehicle-wide impacts, must be

  20. Effects of Fault Displacement on Emplacement Drifts

    SciTech Connect

    F. Duan

    2000-04-25

    The purpose of this analysis is to evaluate potential effects of fault displacement on emplacement drifts, including drip shields and waste packages emplaced in emplacement drifts. The output from this analysis not only provides data for the evaluation of long-term drift stability but also supports the Engineered Barrier System (EBS) process model report (PMR) and Disruptive Events Report currently under development. The primary scope of this analysis includes (1) examining fault displacement effects in terms of induced stresses and displacements in the rock mass surrounding an emplacement drift and (2 ) predicting fault displacement effects on the drip shield and waste package. The magnitude of the fault displacement analyzed in this analysis bounds the mean fault displacement corresponding to an annual frequency of exceedance of 10{sup -5} adopted for the preclosure period of the repository and also supports the postclosure performance assessment. This analysis is performed following the development plan prepared for analyzing effects of fault displacement on emplacement drifts (CRWMS M&O 2000). The analysis will begin with the identification and preparation of requirements, criteria, and inputs. A literature survey on accommodating fault displacements encountered in underground structures such as buried oil and gas pipelines will be conducted. For a given fault displacement, the least favorable scenario in term of the spatial relation of a fault to an emplacement drift is chosen, and the analysis is then performed analytically. Based on the analysis results, conclusions are made regarding the effects and consequences of fault displacement on emplacement drifts. Specifically, the analysis will discuss loads which can be induced by fault displacement on emplacement drifts, drip shield and/or waste packages during the time period of postclosure.

  1. Paleoseismicity of two historically quiescent faults in Australia: Implications for fault behavior in stable continental regions

    USGS Publications Warehouse

    Crone, A.J.; De Martini, P. M.; Machette, M.M.; Okumura, K.; Prescott, J.R.

    2003-01-01

    Paleoseismic studies of two historically aseismic Quaternary faults in Australia confirm that cratonic faults in stable continental regions (SCR) typically have a long-term behavior characterized by episodes of activity separated by quiescent intervals of at least 10,000 and commonly 100,000 years or more. Studies of the approximately 30-km-long Roopena fault in South Australia and the approximately 30-km-long Hyden fault in Western Australia document multiple Quaternary surface-faulting events that are unevenly spaced in time. The episodic clustering of events on cratonic SCR faults may be related to temporal fluctuations of fault-zone fluid pore pressures in a volume of strained crust. The long-term slip rate on cratonic SCR faults is extremely low, so the geomorphic expression of many cratonic SCR faults is subtle, and scarps may be difficult to detect because they are poorly preserved. Both the Roopena and Hyden faults are in areas of limited or no significant seismicity; these and other faults that we have studied indicate that many potentially hazardous SCR faults cannot be recognized solely on the basis of instrumental data or historical earthquakes. Although cratonic SCR faults may appear to be nonhazardous because they have been historically aseismic, those that are favorably oriented for movement in the current stress field can and have produced unexpected damaging earthquakes. Paleoseismic studies of modern and prehistoric SCR faulting events provide the basis for understanding of the long-term behavior of these faults and ultimately contribute to better seismic-hazard assessments.

  2. Fault Tolerant Homopolar Magnetic Bearings

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  3. Illuminating Northern California's Active Faults

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

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

  4. Intermittent/transient fault phenomena in digital systems

    NASA Technical Reports Server (NTRS)

    Masson, G. M.

    1977-01-01

    An overview of the intermittent/transient (IT) fault study is presented. An interval survivability evaluation of digital systems for IT faults is discussed along with a method for detecting and diagnosing IT faults in digital systems.

  5. Implementation of a model based fault detection and diagnosis technique for actuation faults of the SSME

    NASA Technical Reports Server (NTRS)

    Duyar, A.; Guo, T.-H.; Merrill, W.; Musgrave, J.

    1991-01-01

    In a previous study, Guo, Merrill and Duyar, 1990, reported a conceptual development of a fault detection and diagnosis system for actuation faults of the Space Shuttle main engine. This study, which is a continuation of the previous work, implements the developed fault detection and diagnosis scheme for the real time actuation fault diagnosis of the Space Shuttle Main Engine. The scheme will be used as an integral part of an intelligent control system demonstration experiment at NASA Lewis. The diagnosis system utilizes a model based method with real time identification and hypothesis testing for actuation, sensor, and performance degradation faults.

  6. Fault-tolerant software - Experiment with the sift operating system. [Software Implemented Fault Tolerance computer

    NASA Technical Reports Server (NTRS)

    Brunelle, J. E.; Eckhardt, D. E., Jr.

    1985-01-01

    Results are presented of an experiment conducted in the NASA Avionics Integrated Research Laboratory (AIRLAB) to investigate the implementation of fault-tolerant software techniques on fault-tolerant computer architectures, in particular the Software Implemented Fault Tolerance (SIFT) computer. The N-version programming and recovery block techniques were implemented on a portion of the SIFT operating system. The results indicate that, to effectively implement fault-tolerant software design techniques, system requirements will be impacted and suggest that retrofitting fault-tolerant software on existing designs will be inefficient and may require system modification.

  7. The width of fault zones in a brittle-viscous lithosphere: Strike-slip faults

    NASA Technical Reports Server (NTRS)

    Parmentier, E. M.

    1991-01-01

    A fault zone in an ideal brittle material overlying a very weak substrate could, in principle, consist of a single slip surface. Real fault zones have a finite width consisting of a number of nearly parallel slip surfaces on which deformation is distributed. The hypothesis that the finite width of fault zones reflects stresses due to quasistatic flow in the ductile substrate of a brittle surface layer is explored. Because of the simplicity of theory and observations, strike-slip faults are examined first, but the analysis can be extended to normal and thrust faulting.

  8. Glossary of fault and other fracture networks

    NASA Astrophysics Data System (ADS)

    Peacock, D. C. P.; Nixon, C. W.; Rotevatn, A.; Sanderson, D. J.; Zuluaga, L. F.

    2016-11-01

    Increased interest in the two- and three-dimensional geometries and development of faults and other types of fractures in rock has led to an increasingly bewildering terminology. Here we give definitions for the geometric, topological, kinematic and mechanical relationships between geological faults and other types of fractures, focussing on how they relate to form networks.

  9. Diagnostics Tools Identify Faults Prior to Failure

    NASA Technical Reports Server (NTRS)

    2013-01-01

    Through the SBIR program, Rochester, New York-based Impact Technologies LLC collaborated with Ames Research Center to commercialize the Center s Hybrid Diagnostic Engine, or HyDE, software. The fault detecting program is now incorporated into a software suite that identifies potential faults early in the design phase of systems ranging from printers to vehicles and robots, saving time and money.

  10. A Game Theoretic Fault Detection Filter

    NASA Technical Reports Server (NTRS)

    Chung, Walter H.; Speyer, Jason L.

    1995-01-01

    The fault detection process is modelled as a disturbance attenuation problem. The solution to this problem is found via differential game theory, leading to an H(sub infinity) filter which bounds the transmission of all exogenous signals save the fault to be detected. For a general class of linear systems which includes some time-varying systems, it is shown that this transmission bound can be taken to zero by simultaneously bringing the sensor noise weighting to zero. Thus, in the limit, a complete transmission block can he achieved, making the game filter into a fault detection filter. When we specialize this result to time-invariant system, it is found that the detection filter attained in the limit is identical to the well known Beard-Jones Fault Detection Filter. That is, all fault inputs other than the one to be detected (the "nuisance faults") are restricted to an invariant subspace which is unobservable to a projection on the output. For time-invariant systems, it is also shown that in the limit, the order of the state-space and the game filter can be reduced by factoring out the invariant subspace. The result is a lower dimensional filter which can observe only the fault to be detected. A reduced-order filter can also he generated for time-varying systems, though the computational overhead may be intensive. An example given at the end of the paper demonstrates the effectiveness of the filter as a tool for fault detection and identification.

  11. The Curiosity Mars Rover's Fault Protection Engine

    NASA Technical Reports Server (NTRS)

    Benowitz, Ed

    2014-01-01

    The Curiosity Rover, currently operating on Mars, contains flight software onboard to autonomously handle aspects of system fault protection. Over 1000 monitors and 39 responses are present in the flight software. Orchestrating these behaviors is the flight software's fault protection engine. In this paper, we discuss the engine's design, responsibilities, and present some lessons learned for future missions.

  12. Intermittent/transient faults in digital systems

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  13. 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.

  14. Interactive Instruction in Solving Fault Finding Problems.

    ERIC Educational Resources Information Center

    Brooke, J. B.; And Others

    1978-01-01

    A training program is described which provides, during fault diagnosis, additional information about the relationship between the remaining faults and the available indicators. An interactive computer program developed for this purpose and the first results of experimental training are described. (Author)

  15. Training for Skill in Fault Diagnosis

    ERIC Educational Resources Information Center

    Turner, J. D.

    1974-01-01

    The Knitting, Lace and Net Industry Training Board has developed a training innovation called fault diagnosis training. The entire training process concentrates on teaching based on the experiences of troubleshooters or any other employees whose main tasks involve fault diagnosis and rectification. (Author/DS)

  16. Measurement selection for parametric IC fault diagnosis

    NASA Technical Reports Server (NTRS)

    Wu, A.; Meador, J.

    1991-01-01

    Experimental results obtained with the use of measurement reduction for statistical IC fault diagnosis are described. The reduction method used involves data pre-processing in a fashion consistent with a specific definition of parametric faults. The effects of this preprocessing are examined.

  17. The cost of software fault tolerance

    NASA Technical Reports Server (NTRS)

    Migneault, G. E.

    1982-01-01

    The proposed use of software fault tolerance techniques as a means of reducing software costs in avionics and as a means of addressing the issue of system unreliability due to faults in software is examined. A model is developed to provide a view of the relationships among cost, redundancy, and reliability which suggests strategies for software development and maintenance which are not conventional.

  18. Fault detection with principal component pursuit method

    NASA Astrophysics Data System (ADS)

    Pan, Yijun; Yang, Chunjie; Sun, Youxian; An, Ruqiao; Wang, Lin

    2015-11-01

    Data-driven approaches are widely applied for fault detection in industrial process. Recently, a new method for fault detection called principal component pursuit(PCP) is introduced. PCP is not only robust to outliers, but also can accomplish the objectives of model building, fault detection, fault isolation and process reconstruction simultaneously. PCP divides the data matrix into two parts: a fault-free low rank matrix and a sparse matrix with sensor noise and process fault. The statistics presented in this paper fully utilize the information in data matrix. Since the low rank matrix in PCP is similar to principal components matrix in PCA, a T2 statistic is proposed for fault detection in low rank matrix. And this statistic can illustrate that PCP is more sensitive to small variations in variables than PCA. In addition, in sparse matrix, a new monitored statistic performing the online fault detection with PCP-based method is introduced. This statistic uses the mean and the correlation coefficient of variables. Monte Carlo simulation and Tennessee Eastman (TE) benchmark process are provided to illustrate the effectiveness of monitored statistics.

  19. Runtime Speculative Software-Only Fault Tolerance

    DTIC Science & Technology

    2012-06-01

    5.6.2 Memory consumption . . . . . . . . . . . . . . . . . . . . . . . . 61 5.6.3 Power consumption...Overhead . . . . . . . . . . . . . . . . . . . . . . . . . . 68 6.2.2 Physical Memory Usage . . . . . . . . . . . . . . . . . . . . . . . 69 6.2.3 Power ...overhead for RSFT with and without fault recovery. . . . 70 6.5 Physical memory overhead for RSFT with and without fault recovery. . . . 72 6.6 Power

  20. Investigation of an Advanced Fault Tolerant Integrated Avionics System

    DTIC Science & Technology

    1986-03-01

    Fault Detection and Isolation 50 5.4.2 Cockpit Fault Monitoring and Reconfiguration 53 Logical...Management Design Considerations 5.2.2.1 Authority Hierarchy Redundancy management involves not only fault detection and isolation but action to deselect... Fault Detection and Isolation in the event of a fault in an active channel, three events must transpire: a) The fault must be detected, b) The

  1. Geophysical characterization of buried active faults: the Concud Fault (Iberian Chain, NE Spain)

    NASA Astrophysics Data System (ADS)

    Pueyo Anchuela, Óscar; Lafuente, Paloma; Arlegui, Luis; Liesa, Carlos L.; Simón, José L.

    2016-11-01

    The Concud Fault is a 14-km-long active fault that extends close to Teruel, a city with about 35,000 inhabitants in the Iberian Range (NE Spain). It shows evidence of recurrent activity during Late Pleistocene time, posing a significant seismic hazard in an area of moderate-to-low tectonic rates. A geophysical survey was carried out along the mapped trace of the southern branch of the Concud Fault to evaluate the geophysical signature from the fault and the location of paleoseismic trenches. The survey identified a lineation of inverse magnetic dipoles at residual and vertical magnetic gradient, a local increase in apparent conductivity, and interruptions of the underground sediment structure along GPR profiles. The origin of these anomalies is due to lateral contrast between both fault blocks and the geophysical signature of Quaternary materials located above and directly south of the fault. The spatial distribution of anomalies was successfully used to locate suitable trench sites and to map non-exposed segments of the fault. The geophysical anomalies are related to the sedimentological characteristics and permeability differences of the deposits and to deformation related to fault activity. The results illustrate the usefulness of geophysics to detect and map non-exposed faults in areas of moderate-to-low tectonic activity where faults are often covered by recent pediments that obscure geological evidence of the most recent earthquakes. The results also highlight the importance of applying multiple geophysical techniques in defining the location of buried faults.

  2. Fault structure, frictional properties and mixed-mode fault slip behavior

    NASA Astrophysics Data System (ADS)

    Collettini, Cristiano; Niemeijer, André; Viti, Cecilia; Smith, Steven A. F.; Marone, Chris

    2011-11-01

    Recent high-resolution GPS and seismological data reveal that tectonic faults exhibit complex, multi-mode slip behavior including earthquakes, creep events, slow and silent earthquakes, low-frequency events and earthquake afterslip. The physical processes responsible for this range of behavior and the mechanisms that dictate fault slip rate or rupture propagation velocity are poorly understood. One avenue for improving knowledge of these mechanisms involves coupling direct observations of ancient faults exhumed at the Earth's surface with laboratory experiments on the frictional properties of the fault rocks. Here, we show that fault zone structure has an important influence on mixed-mode fault slip behavior. Our field studies depict a complex fault zone structure where foliated horizons surround meter- to decameter-sized lenses of competent material. The foliated rocks are composed of weak mineral phases, possess low frictional strength, and exhibit inherently stable, velocity-strengthening frictional behavior. In contrast, the competent lenses are made of strong minerals, possess high frictional strength, and exhibit potentially unstable, velocity-weakening frictional behavior. Tectonic loading of this heterogeneous fault zone may initially result in fault creep along the weak and frictionally stable foliated horizons. With continued deformation, fault creep will concentrate stress within and around the strong and potentially unstable competent lenses, which may lead to earthquake nucleation. Our studies provide field and mechanical constraints for complex, mixed-mode fault slip behavior ranging from repeating earthquakes to transient slip, episodic slow-slip and creep events.

  3. Spatial analysis of hypocenter to fault relationships for determining fault process zone width in Japan.

    SciTech Connect

    Arnold, Bill Walter; Roberts, Barry L.; McKenna, Sean Andrew; Coburn, Timothy C. (Abilene Christian University, Abilene, TX)

    2004-09-01

    Preliminary investigation areas (PIA) for a potential repository of high-level radioactive waste must be evaluated by NUMO with regard to a number of qualifying factors. One of these factors is related to earthquakes and fault activity. This study develops a spatial statistical assessment method that can be applied to the active faults in Japan to perform such screening evaluations. This analysis uses the distribution of seismicity near faults to define the width of the associated process zone. This concept is based on previous observations of aftershock earthquakes clustered near active faults and on the assumption that such seismic activity is indicative of fracturing and associated impacts on bedrock integrity. Preliminary analyses of aggregate data for all of Japan confirmed that the frequency of earthquakes is higher near active faults. Data used in the analysis were obtained from NUMO and consist of three primary sources: (1) active fault attributes compiled in a spreadsheet, (2) earthquake hypocenter data, and (3) active fault locations. Examination of these data revealed several limitations with regard to the ability to associate fault attributes from the spreadsheet to locations of individual fault trace segments. In particular, there was no direct link between attributes of the active faults in the spreadsheet and the active fault locations in the GIS database. In addition, the hypocenter location resolution in the pre-1983 data was less accurate than for later data. These pre-1983 hypocenters were eliminated from further analysis.

  4. Modeling fault among motorcyclists involved in crashes.

    PubMed

    Haque, Md Mazharul; Chin, Hoong Chor; Huang, Helai

    2009-03-01

    Singapore crash statistics from 2001 to 2006 show that the motorcyclist fatality and injury rates per registered vehicle are higher than those of other motor vehicles by 13 and 7 times, respectively. The crash involvement rate of motorcyclists as victims of other road users is also about 43%. The objective of this study is to identify the factors that contribute to the fault of motorcyclists involved in crashes. This is done by using the binary logit model to differentiate between at-fault and not-at-fault cases and the analysis is further categorized by the location of the crashes, i.e., at intersections, on expressways and at non-intersections. A number of explanatory variables representing roadway characteristics, environmental factors, motorcycle descriptions, and rider demographics have been evaluated. Time trend effect shows that not-at-fault crash involvement of motorcyclists has increased with time. The likelihood of night time crashes has also increased for not-at-fault crashes at intersections and expressways. The presence of surveillance cameras is effective in reducing not-at-fault crashes at intersections. Wet-road surfaces increase at-fault crash involvement at non-intersections. At intersections, not-at-fault crash involvement is more likely on single-lane roads or on median lane of multi-lane roads, while on expressways at-fault crash involvement is more likely on the median lane. Roads with higher speed limit have higher at-fault crash involvement and this is also true on expressways. Motorcycles with pillion passengers or with higher engine capacity have higher likelihood of being at-fault in crashes on expressways. Motorcyclists are more likely to be at-fault in collisions involving pedestrians and this effect is higher at night. In multi-vehicle crashes, motorcyclists are more likely to be victims than at-fault. Young and older riders are more likely to be at-fault in crashes than middle-aged group of riders. The findings of this study will help

  5. Active faulting in the Walker Lane

    NASA Astrophysics Data System (ADS)

    Wesnousky, Steven G.

    2005-06-01

    Deformation across the San Andreas and Walker Lane fault systems accounts for most relative Pacific-North American transform plate motion. The Walker Lane is composed of discontinuous sets of right-slip faults that are located to the east and strike approximately parallel to the San Andreas fault system. Mapping of active faults in the central Walker Lane shows that right-lateral shear is locally accommodated by rotation of crustal blocks bounded by steep-dipping east striking left-slip faults. The left slip and clockwise rotation of crustal blocks bounded by the east striking faults has produced major basins in the area, including Rattlesnake and Garfield flats; Teels, Columbus and Rhodes salt marshes; and Queen Valley. The Benton Springs and Petrified Springs faults are the major northwest striking structures currently accommodating transform motion in the central Walker Lane. Right-lateral offsets of late Pleistocene surfaces along the two faults point to slip rates of at least 1 mm/yr. The northern limit of northwest trending strike-slip faults in the central Walker Lane is abrupt and reflects transfer of strike-slip to dip-slip deformation in the western Basin and Range and transformation of right slip into rotation of crustal blocks to the north. The transfer of strike slip in the central Walker Lane to dip slip in the western Basin and Range correlates to a northward broadening of the modern strain field suggested by geodesy and appears to be a long-lived feature of the deformation field. The complexity of faulting and apparent rotation of crustal blocks within the Walker Lane is consistent with the concept of a partially detached and elastic-brittle crust that is being transported on a continuously deforming layer below. The regional pattern of faulting within the Walker Lane is more complex than observed along the San Andreas fault system to the west. The difference is attributed to the relatively less cumulative slip that has occurred across the Walker

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

    SciTech Connect

    Boles, James

    2013-05-24

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

  7. Shear heating by translational brittle reverse faulting along a single, sharp and straight fault plane

    NASA Astrophysics Data System (ADS)

    Mukherjee, Soumyajit

    2017-02-01

    Shear heating by reverse faulting on a sharp straight fault plane is modelled. Increase in temperature ( T i ) of faulted hangingwall and footwall blocks by frictional/shear heating for planar rough reverse faults is proportional to the coefficient of friction ( μ), density and thickness of the hangingwall block ( ρ). T i increases as movement progresses with time. Thermal conductivity ( K i ) and thermal diffusivity (ki^' }) of faulted blocks govern T i but they do not bear simple relation. T i is significant only near the fault plane. If the lithology is dry and faulting brings adjacent hangingwall and footwall blocks of the same lithology in contact, those blocks undergo the same rate of increase in shear heating per unit area per unit time.

  8. Tuning of fault tolerant control design parameters.

    PubMed

    DeLima, Pedro G; Yen, Gary G

    2008-01-01

    This paper presents two major contributions in the field of fault tolerant control. First, it gathers points of concern typical to most fault tolerant control applications and translates the chosen performance metrics into a set of six practical design specifications. Second, it proposes initialization and tuning procedures through which a particular fault tolerant control architecture not only can be set to comply with the required specifications, but also can be tuned online to compensate for a total of twelve properties, such as the noise rejection levels for fault detection and diagnosis signals. The proposed design is realized over a powerful architecture that combines the flexibility of adaptive critic designs with the long term memory and learning capabilities of a supervisor. This paper presents a practical design procedure to facilitate the applications of a fundamentally sound fault tolerant control architecture in real-world problems.

  9. Classification of Aircraft Maneuvers for Fault Detection

    NASA Technical Reports Server (NTRS)

    Oza, Nikunj; Tumer, Irem Y.; Tumer, Kagan; Huff, Edward M.; Koga, Dennis (Technical Monitor)

    2002-01-01

    Automated fault detection is an increasingly important problem in aircraft maintenance and operation. Standard methods of fault detection assume the availability of either data produced during all possible faulty operation modes or a clearly-defined means to determine whether the data provide a reasonable match to known examples of proper operation. In the domain of fault detection in aircraft, the first assumption is unreasonable and the second is difficult to determine. We envision a system for online fault detection in aircraft, one part of which is a classifier that predicts the maneuver being performed by the aircraft as a function of vibration data and other available data. To develop such a system, we use flight data collected under a controlled test environment, subject to many sources of variability. We explain where our classifier fits into the envisioned fault detection system as well as experiments showing the promise of this classification subsystem.

  10. Maneuver Classification for Aircraft Fault Detection

    NASA Technical Reports Server (NTRS)

    Oza, Nikunj C.; Tumer, Irem Y.; Tumer, Kagan; Huff, Edward M.

    2003-01-01

    Automated fault detection is an increasingly important problem in aircraft maintenance and operation. Standard methods of fault detection assume the availability of either data produced during all possible faulty operation modes or a clearly-defined means to determine whether the data provide a reasonable match to known examples of proper operation. In the domain of fault detection in aircraft, identifying all possible faulty and proper operating modes is clearly impossible. We envision a system for online fault detection in aircraft, one part of which is a classifier that predicts the maneuver being performed by the aircraft as a function of vibration data and other available data. To develop such a system, we use flight data collected under a controlled test environment, subject to many sources of variability. We explain where our classifier fits into the envisioned fault detection system as well as experiments showing the promise of this classification subsystem.

  11. Classification of Aircraft Maneuvers for Fault Detection

    NASA Technical Reports Server (NTRS)

    Oza, Nikunj C.; Tumer, Irem Y.; Tumer, Kagan; Huff, Edward M.; Clancy, Daniel (Technical Monitor)

    2002-01-01

    Automated fault detection is an increasingly important problem in aircraft maintenance and operation. Standard methods of fault detection assume the availability of either data produced during all possible faulty operation modes or a clearly-defined means to determine whether the data is a reasonable match to known examples of proper operation. In our domain of fault detection in aircraft, the first assumption is unreasonable and the second is difficult to determine. We envision a system for online fault detection in aircraft, one part of which is a classifier that predicts the maneuver being performed by the aircraft as a function of vibration data and other available data. We explain where this subsystem fits into our envisioned fault detection system as well its experiments showing the promise of this classification subsystem.

  12. Fault analysis of multichannel spacecraft power systems

    NASA Technical Reports Server (NTRS)

    Dugal-Whitehead, Norma R.; Lollar, Louis F.

    1990-01-01

    The NASA Marshall Space Flight Center proposes to implement computer-controlled fault injection into an electrical power system breadboard to study the reactions of the various control elements of this breadboard. Elements under study include the remote power controllers, the algorithms in the control computers, and the artificially intelligent control programs resident in this breadboard. To this end, a study of electrical power system faults is being performed to yield a list of the most common power system faults. The results of this study will be applied to a multichannel high-voltage DC spacecraft power system called the large autonomous spacecraft electrical power system (LASEPS) breadboard. The results of the power system fault study and the planned implementation of these faults into the LASEPS breadboard are described.

  13. Holocene fault scarps in the Western Alps

    NASA Astrophysics Data System (ADS)

    Hippolyte, J. C.

    2003-04-01

    In the Tarentaise Valley, Goguel (1969) had described recent fault scarps. The present work shows that they are normal faults indicating a SE-directed trend of extension in agreement with recent microseismicity data (Sue et al., 1999). It is proposed that they reflect the Quaternary normal reactivation of the "Front du Houiller" thrust fault. In the Belledonne external crystalline massif, Bordet (1970) had observed from helicopter three main fault scarps that he interpreted as active SE-dipping reverse faults. Partly owing to the difficulties of access this area was not visited until now. Field observations reveal that these faults dip in fact 61-68° to the NW, and are normal faults. The faults scarps are 1 to 13 meters high. These faults, together with at least 10 newly discovered conjugate SE-dipping normal fault scarps of 0.5 to 18 meters high, form an about 2 km wide fault zone along the "Synclinal Median" (S.M.) fault. They attest for the activity of this 70 km-long NNE-striking main fault running in the middle of the Belledonne Massif. Its activity is confirmed by major faceted spurs at the La Perche, the La Perrière and the Claran passes, and by ruptures cutting moraines. Other fault scarps are discovered in the whole Belledonne massif showing in particular that the Font-de-France fault, a 60 km-long SE-dipping fault, is also active. All the observed active faults are normal. Their offsets of mountains slopes, of screes and of rock glacier morphologies demonstrate their activity during the Holocene. They indicate a present SE-directed extension in agreement with recent GPS data (Calais et al., 2002). This mapping shows that the present extensional deformation of the Alps is not limited to the west by the "Frontal Pennine thrust" (Sue et al., 1999) but affects also the external Alps. Taking into account focal plane mechanisms, extension affects at least 70 % of the Western Alps. Some scarps have been sampled for Beryllium cosmogenic dating. However

  14. Self-triggering superconducting fault current limiter

    DOEpatents

    Yuan, Xing; Tekletsadik, Kasegn

    2008-10-21

    A modular and scaleable Matrix Fault Current Limiter (MFCL) that functions as a "variable impedance" device in an electric power network, using components made of superconducting and non-superconducting electrically conductive materials. The matrix fault current limiter comprises a fault current limiter module that includes a superconductor which is electrically coupled in parallel with a trigger coil, wherein the trigger coil is magnetically coupled to the superconductor. The current surge doing a fault within the electrical power network will cause the superconductor to transition to its resistive state and also generate a uniform magnetic field in the trigger coil and simultaneously limit the voltage developed across the superconductor. This results in fast and uniform quenching of the superconductors, significantly reduces the burnout risk associated with non-uniformity often existing within the volume of superconductor materials. The fault current limiter modules may be electrically coupled together to form various "n" (rows).times."m" (columns) matrix configurations.

  15. Quantifying fault recovery in multiprocessor systems

    NASA Technical Reports Server (NTRS)

    Malek, Miroslaw; Harary, Frank

    1990-01-01

    Various aspects of reliable computing are formalized and quantified with emphasis on efficient fault recovery. The mathematical model which proves to be most appropriate is provided by the theory of graphs. New measures for fault recovery are developed and the value of elements of the fault recovery vector are observed to depend not only on the computation graph H and the architecture graph G, but also on the specific location of a fault. In the examples, a hypercube is chosen as a representative of parallel computer architecture, and a pipeline as a typical configuration for program execution. Dependability qualities of such a system is defined with or without a fault. These qualities are determined by the resiliency triple defined by three parameters: multiplicity, robustness, and configurability. Parameters for measuring the recovery effectiveness are also introduced in terms of distance, time, and the number of new, used, and moved nodes and edges.

  16. Fault Detection for Automotive Shock Absorber

    NASA Astrophysics Data System (ADS)

    Hernandez-Alcantara, Diana; Morales-Menendez, Ruben; Amezquita-Brooks, Luis

    2015-11-01

    Fault detection for automotive semi-active shock absorbers is a challenge due to the non-linear dynamics and the strong influence of the disturbances such as the road profile. First obstacle for this task, is the modeling of the fault, which has been shown to be of multiplicative nature. Many of the most widespread fault detection schemes consider additive faults. Two model-based fault algorithms for semiactive shock absorber are compared: an observer-based approach and a parameter identification approach. The performance of these schemes is validated and compared using a commercial vehicle model that was experimentally validated. Early results shows that a parameter identification approach is more accurate, whereas an observer-based approach is less sensible to parametric uncertainty.

  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. Methodology for Designing Fault-Protection Software

    NASA Technical Reports Server (NTRS)

    Barltrop, Kevin; Levison, Jeffrey; Kan, Edwin

    2006-01-01

    A document describes a methodology for designing fault-protection (FP) software for autonomous spacecraft. The methodology embodies and extends established engineering practices in the technical discipline of Fault Detection, Diagnosis, Mitigation, and Recovery; and has been successfully implemented in the Deep Impact Spacecraft, a NASA Discovery mission. Based on established concepts of Fault Monitors and Responses, this FP methodology extends the notion of Opinion, Symptom, Alarm (aka Fault), and Response with numerous new notions, sub-notions, software constructs, and logic and timing gates. For example, Monitor generates a RawOpinion, which graduates into Opinion, categorized into no-opinion, acceptable, or unacceptable opinion. RaiseSymptom, ForceSymptom, and ClearSymptom govern the establishment and then mapping to an Alarm (aka Fault). Local Response is distinguished from FP System Response. A 1-to-n and n-to- 1 mapping is established among Monitors, Symptoms, and Responses. Responses are categorized by device versus by function. Responses operate in tiers, where the early tiers attempt to resolve the Fault in a localized step-by-step fashion, relegating more system-level response to later tier(s). Recovery actions are gated by epoch recovery timing, enabling strategy, urgency, MaxRetry gate, hardware availability, hazardous versus ordinary fault, and many other priority gates. This methodology is systematic, logical, and uses multiple linked tables, parameter files, and recovery command sequences. The credibility of the FP design is proven via a fault-tree analysis "top-down" approach, and a functional fault-mode-effects-and-analysis via "bottoms-up" approach. Via this process, the mitigation and recovery strategy(s) per Fault Containment Region scope (width versus depth) the FP architecture.

  19. 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

  20. [Feeding habits and trophic ecology of the fish Lutjanus griseus (Pisces: Lutjanidae) associated with submerged vegetation in Laguna de Términos, Campeche, Mexico].

    PubMed

    Guevara, Emma; Alvarez, Hernán; Mascaró, Maite; Rosas, Carlos; Sánchez, Alberto

    2007-01-01

    In Campeche, Mexico, the Laguna de Términos has Thalassia testudinum beds inhabited by the grey snapper, Lutjanus griseus (Linnaeus 1758). Along one year, we collected 994 individuals and 672 had food in their stomachs; we recorded number, weight, and frequency oftrophic groups, and the index of relative importance. Dominant food components were Farfantepenaeus duorarum and Palemonetes octaviae, Eucinostomus gula (Cuvier 1830) and Libinia dubia. Salinity and temperature were related to the number of individuals collected and with greater fish consumption by large L. griseus. The trophic niche breadth index was calculated for six size-classes of fish. The smallest and the largest fish had the lowest index values, whereas medium-size snappers had higher values. This snapper has a preference for habitats with submerged vegetation. The percentage of fish with food in their stomachs was higher during dark hours, providing evidence of the nocturnal habits of this fish.

  1. The stratified microbial community at Laguna Figueroa, Baja California, Mexico: A possible model for prephanerozoic laminated microbial communities preserved in cherts

    NASA Astrophysics Data System (ADS)

    Stolz, John F.; Margulis, Lynn

    1984-12-01

    The microbial mat community of the evaporite flat at North Pond, Laguna Figueroa (Baja California, Mexico) was actively involved in the production of laminated sediments prior to 1978. Heavy rains in 1979 and 1980 flooded the mat with 1 and 3 meters of meteoric water respectively. The flooding deposited up to 10 cm of silicoclastic sediment over theMicrocoleus-dominated mat and resulted in the cessation of laminated sediment deposition. In 1982, the surface had been recolonized by species of cyanobacteria (Spirulina, Oscillatoria) and purple photosynthetic bacteria (Chromatium, Thiocapsa). The silicoclastic sediments and residual evaporites, which overlaid the laminated sediment, had been reworked into an anaerobic, sulfide-rich mud and contained well preserved sheaths of filamentous and coccoid bacteria.

  2. Rapid uplift in Laguna del Maule volcanic field of the Andean Southern Volcanic Zone (Chile) measured by satellite radar interferometry

    NASA Astrophysics Data System (ADS)

    Feigl, K.; Ali, T.; Singer, B. S.; Pesicek, J. D.; Thurber, C. H.; Jicha, B. R.; Lara, L. E.; Hildreth, E. W.; Fierstein, J.; Williams-Jones, G.; Unsworth, M. J.; Keranen, K. M.

    2011-12-01

    The Laguna del Maule (LdM) volcanic field of the Andean Southern Volcanic Zone extends over 500 square kilometers and comprises more than 130 individual vents. As described by Hildreth et al. (2010), the history has been defined from sixty-eight Ar/Ar and K-Ar dates. Silicic eruptions have occurred throughout the past 3.7 Ma, including welded ignimbrite associated with caldera formation at 950 ka, small rhyolitic eruptions between 336 and 38 ka, and a culminating ring of 36 post-glacial rhyodacite and rhyolite coulees and domes that encircle the lake. Dating of five post-glacial flows implies that these silicic eruptions occurred within the last 25 kyr. Field relations indicate that initial eruptions comprised modest volumes of mafic rhyodacite magma that were followed by larger volumes of high silica rhyolite. The post-glacial flare-up of silicic magmatism from vents distributed around the lake, is unprecedented in the history of this volcanic field. Using satellite radar interferometry (InSAR), Fournier et al. (2010) measured uplift at a rate of more than 180 mm/year between 2007 and 2008 in a round pattern centered on the west side of LdM. More recent InSAR observations suggest that rapid uplift has continued from 2008 through early 2011. In contrast, Fournier et al. found no measurable deformation in an interferogram spanning 2003 through 2004. In this study, we model the deformation field using the General Inversion of Phase Technique (GIPhT), as described by Feigl and Thurber (2009). Two different models fit the data. The first model assumes a sill at ~5 km depth has been inflating at a rate of more than 20 million cubic meters per year since 2007. The second model assumes that the water level in the lake dropped at a rate of 20 m/yr from January 2007 through February 2010, thus reducing the load on an elastic simulation of the crust. The rate of intrusion inferred from InSAR is an order of magnitude higher than the average rate derived from well-dated arc

  3. An observer based approach for achieving fault diagnosis and fault tolerant control of systems modeled as hybrid Petri nets.

    PubMed

    Renganathan, K; Bhaskar, VidhyaCharan

    2011-07-01

    In this paper, we propose an approach for achieving detection and identification of faults, and provide fault tolerant control for systems that are modeled using timed hybrid Petri nets. For this purpose, an observer based technique is adopted which is useful in detection of faults, such as sensor faults, actuator faults, signal conditioning faults, etc. The concepts of estimation, reachability and diagnosability have been considered for analyzing faulty behaviors, and based on the detected faults, different schemes are proposed for achieving fault tolerant control using optimization techniques. These concepts are applied to a typical three tank system and numerical results are obtained.

  4. Fault failure with moderate earthquakes

    USGS Publications Warehouse

    Johnston, M.J.S.; Linde, A.T.; Gladwin, M.T.; Borcherdt, R.D.

    1987-01-01

    High resolution strain and tilt recordings were made in the near-field of, and prior to, the May 1983 Coalinga earthquake (ML = 6.7, ?? = 51 km), the August 4, 1985, Kettleman Hills earthquake (ML = 5.5, ?? = 34 km), the April 1984 Morgan Hill earthquake (ML = 6.1, ?? = 55 km), the November 1984 Round Valley earthquake (ML = 5.8, ?? = 54 km), the January 14, 1978, Izu, Japan earthquake (ML = 7.0, ?? = 28 km), and several other smaller magnitude earthquakes. These recordings were made with near-surface instruments (resolution 10-8), with borehole dilatometers (resolution 10-10) and a 3-component borehole strainmeter (resolution 10-9). While observed coseismic offsets are generally in good agreement with expectations from elastic dislocation theory, and while post-seismic deformation continued, in some cases, with a moment comparable to that of the main shock, preseismic strain or tilt perturbations from hours to seconds (or less) before the main shock are not apparent above the present resolution. Precursory slip for these events, if any occurred, must have had a moment less than a few percent of that of the main event. To the extent that these records reflect general fault behavior, the strong constraint on the size and amount of slip triggering major rupture makes prediction of the onset times and final magnitudes of the rupture zones a difficult task unless the instruments are fortuitously installed near the rupture initiation point. These data are best explained by an inhomogeneous failure model for which various areas of the fault plane have either different stress-slip constitutive laws or spatially varying constitutive parameters. Other work on seismic waveform analysis and synthetic waveforms indicates that the rupturing process is inhomogeneous and controlled by points of higher strength. These models indicate that rupture initiation occurs at smaller regions of higher strength which, when broken, allow runaway catastrophic failure. ?? 1987.

  5. Robot Position Sensor Fault Tolerance

    NASA Technical Reports Server (NTRS)

    Aldridge, Hal A.

    1997-01-01

    Robot systems in critical applications, such as those in space and nuclear environments, must be able to operate during component failure to complete important tasks. One failure mode that has received little attention is the failure of joint position sensors. Current fault tolerant designs require the addition of directly redundant position sensors which can affect joint design. A new method is proposed that utilizes analytical redundancy to allow for continued operation during joint position sensor failure. Joint torque sensors are used with a virtual passive torque controller to make the robot joint stable without position feedback and improve position tracking performance in the presence of unknown link dynamics and end-effector loading. Two Cartesian accelerometer based methods are proposed to determine the position of the joint. The joint specific position determination method utilizes two triaxial accelerometers attached to the link driven by the joint with the failed position sensor. The joint specific method is not computationally complex and the position error is bounded. The system wide position determination method utilizes accelerometers distributed on different robot links and the end-effector to determine the position of sets of multiple joints. The system wide method requires fewer accelerometers than the joint specific method to make all joint position sensors fault tolerant but is more computationally complex and has lower convergence properties. Experiments were conducted on a laboratory manipulator. Both position determination methods were shown to track the actual position satisfactorily. A controller using the position determination methods and the virtual passive torque controller was able to servo the joints to a desired position during position sensor failure.

  6. Rock-magnetic signature of precipitation and extreme runoff events in south-eastern Patagonia since 51,200 cal BP from the sediments of Laguna Potrok Aike

    NASA Astrophysics Data System (ADS)

    Lisé-Pronovost, A.; St-Onge, G.; Gogorza, C.; Jouve, G.; Francus, P.; Zolitschka, B.

    2014-08-01

    A 106-m long sediment sequence from the maar lake Laguna Potrok Aike in southern Patagonia was recovered in the framework of the International Continental Scientific Drilling Program (ICDP) Potrok Aike maar lake Sediment Archive Drilling prOject (PASADO). About half of the sedimentary sequence is composed of mass movement deposits (MMDs) and the event-corrected record reaches back to 51,200 cal BP. Here we present a high-resolution rock-magnetic study revealing two sedimentary facies associated with MMDs and characterized by two different types of spurious gyroremanent magnetization (GRM) acquired during static alternating field demagnetization. The first rock-magnetic signature is detected in MMDs composed of reworked sand and tephra material. The signature consists of GRM acquired during demagnetization of the natural remanent magnetization (NRM) and other rock-magnetic properties typical of iron sulfides such as greigite. We interpret these intervals as authigenic formation of iron sulfides in suboxic conditions within the MMD. The second rock-magnetic signature consists of a series of 10 short intervals located on the top of MMDs characterized by GRM acquisition during demagnetization of the isothermal remanent magnetization (IRM). Based on geological, limnological, stratigraphic and climatic evidence these layers are interpreted as reflecting pedogenic hematite and/or goethite brought to the lake by runoff events related to precipitation and permafrost melt. The pedogenic iron minerals mobilized from the catchment most likely settled out of suspension on top of MMDs after a rapid remobilization event. The series of runoff events corresponds to periods of increased lacustrine productivity in Laguna Potrok Aike and are coeval within the limit of the chronology to warm periods of the Last Glacial as recorded in Antarctica, the deglaciation in the mid-latitudes of the Southern Hemisphere and enhanced precipitation during the Early Holocene in southeastern

  7. Taxonomic and functional metagenomic profiling of the microbial community in the anoxic sediment of a sub-saline shallow lake (Laguna de Carrizo, Central Spain).

    PubMed

    Ferrer, Manuel; Guazzaroni, María-Eugenia; Richter, Michael; García-Salamanca, Adela; Yarza, Pablo; Suárez-Suárez, Ana; Solano, Jennifer; Alcaide, María; van Dillewijn, Pieter; Molina-Henares, Maria Antonia; López-Cortés, Nieves; Al-Ramahi, Yamal; Guerrero, Carmen; Acosta, Alejandro; de Eugenio, Laura I; Martínez, Virginia; Marques, Silvia; Rojo, Fernando; Santero, Eduardo; Genilloud, Olga; Pérez-Pérez, Julian; Rosselló-Móra, Ramón; Ramos, Juan Luis

    2011-11-01

    The phylogenetic and functional structure of the microbial community residing in a Ca(2+)-rich anoxic sediment of a sub-saline shallow lake (Laguna de Carrizo, initially operated as a gypsum (CaSO(4) × 2 H(2)O) mine) was estimated by analyzing the diversity of 16S rRNA amplicons and a 3.1 Mb of consensus metagenome sequence. The lake has about half the salinity of seawater and possesses an unusual relative concentration of ions, with Ca(2+) and SO (4) (2-) being dominant. The 16S rRNA sequences revealed a diverse community with about 22% of the bacterial rRNAs being less than 94.5% similar to any rRNA currently deposited in GenBank. In addition to this, about 79% of the archaeal rRNA genes were mostly related to uncultured Euryarchaeota of the CCA47 group, which are often associated with marine and oxygen-depleted sites. Sequence analysis of assembled genes revealed that 23% of the open reading frames of the metagenome library had no hits in the database. Among annotated genes, functions related to (thio) sulfate and (thio) sulfonate-reduction and iron-oxidation, sulfur-oxidation, denitrification, synthrophism, and phototrophic sulfur metabolism were found as predominant. Phylogenetic and biochemical analyses indicate that the inherent physical-chemical characteristics of this habitat coupled with adaptation to anthropogenic activities have resulted in a highly efficient community for the assimilation of polysulfides, sulfoxides, and organosulfonates together with nitro-, nitrile-, and cyanide-substituted compounds. We discuss that the relevant microbial composition and metabolic capacities at Laguna de Carrizo, likely developed as an adaptation to thrive in the presence of moderate salinity conditions and potential toxic bio-molecules, in contrast with the properties of previously known anoxic sediments of shallow lakes.

  8. 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

  9. High Resolution Seismic Imaging of Fault Zones: Methods and Examples From The San Andreas Fault

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  10. Episodic activity of a dormant fault in tectonically stable Europe: The Rauw fault (NE Belgium)

    NASA Astrophysics Data System (ADS)

    Verbeeck, Koen; Wouters, Laurent; Vanneste, Kris; Camelbeeck, Thierry; Vandenberghe, Dimitri; Beerten, Koen; Rogiers, Bart; Schiltz, Marco; Burow, Christoph; Mees, Florias; De Grave, Johan; Vandenberghe, Noël

    2017-03-01

    Our knowledge about large earthquakes in stable continental regions comes from studies of faults that generated historical surface rupturing earthquakes or were identified by their recent imprint in the morphology. Here, we evaluate the co-seismic character and movement history of the Rauw fault in Belgium, which lacks geomorphological expression and historical/present seismicity. This 55-km-long normal fault, with known Neogene and possibly Early Pleistocene activity, is the largest offset fault west of the active Roer Valley Graben. Its trace was identified in the shallow subsurface based on high resolution geophysics. All the layers within the Late Pliocene Mol Formation (3.6 to 2.59 Ma) are displaced 7 m vertically, without growth faulting, but deeper deposits show increasing offset. A paleoseismic trench study revealed cryoturbated, but unfaulted, late glacial coversands overlying faulted layers of Mol Formation. In-between those deposits, the fault tip was eroded, along with evidence for individual displacement events. Fragmented clay gouge observed in a micromorphology sample of the main fault evidences co-seismic faulting, as opposed to fault creep. Based on optical and electron spin resonance dating and trench stratigraphy, the 7 m combined displacement is bracketed to have occurred between 2.59 Ma and 45 ka. The regional presence of the Sterksel Formation alluvial terrace deposits, limited to the hanging wall of the Rauw fault, indicates a deflection of the Meuse/Rhine confluence (1.0 to 0.5 Ma) by the fault's activity, suggesting that most of the offset occurred prior to/at this time interval. In the trench, Sterksel Formation is eroded but reworked gravel testifies for its former presence. Hence, the Rauw fault appears as typical of plate interior context, with an episodic seismic activity concentrated between 1.0 and 0.5 Ma or at least between 2.59 Ma to 45 ka, possibly related to activity variations in the adjacent, continuously active Roer Valley

  11. Dissecting Oceanic Detachment Faults: Fault Zone Geometry, Deformation Mechanisms, and Nature of Fluid-Rock Interactions

    NASA Astrophysics Data System (ADS)

    Bonnemains, D.; Escartin, J.; Verlaguet, A.; Andreani, M.; Mevel, C.

    2015-12-01

    To understand the extreme strain localization at long-lived oceanic detachment faults rooting deeply below the axis, we present results of geological investigations at the 13°19'N detachment along the Mid-Atlantic Ridge, conducted during the ODEMAR cruise (Nov-Dec13, NO Pourquoi Pas?) with ROV Victor6000 (IFREMER). During this cruise we investigated and sampled the corrugated fault to understand its geometry, nature of deformation, and links to fluid flow. We identified and explored 7 fault outcrops on the flanks of microbathymetric striations subparallel to extension. These outcrops expose extensive fault planes, with the most prominent ones extending 40-90m laterally, and up to 10 m vertically. These fault surfaces systematically show subhorizontal striations subparallel to extension, and define slabs of fault-rock that are flat and also striated at sample scale. Visual observations show a complex detachment fault zone, with anastomosing fault planes at outcrop scale (1-10 m), with a highly heterogeneous distribution of deformation. We observe heterogeneity in fault-rock nature at outcrop scale. In situ samples from striated faults are primarily basalt breccias with prior green-schist facies alteration, and a few ultramafic fault-rocks that show a complex deformation history, with early schistose textures, brittlely reworked as clasts within the fault. The basalt breccias show variable silicification and associated sulfides, recording important fluid-rock interactions during exhumation. To understand the link between fluid and deformation during exhumation, we will present microstructural observation of deformation textures, composition, and distribution and origin of quartz and sulfides, as well as constraints on the temperature of silicifying fluids from fluid inclusions in quartz. These results allow us to characterize in detail the detachment fault zone geometry, and investigate the timing of silicification relative to deformation.

  12. 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

  13. Experimental study on propagation of fault slip along a simulated rock fault

    NASA Astrophysics Data System (ADS)

    Mizoguchi, K.

    2015-12-01

    Around pre-existing geological faults in the crust, we have often observed off-fault damage zone where there are many fractures with various scales, from ~ mm to ~ m and their density typically increases with proximity to the fault. One of the fracture formation processes is considered to be dynamic shear rupture propagation on the faults, which leads to the occurrence of earthquakes. Here, I have conducted experiments on propagation of fault slip along a pre-cut rock surface to investigate the damaging behavior of rocks with slip propagation. For the experiments, I used a pair of metagabbro blocks from Tamil Nadu, India, of which the contacting surface simulates a fault of 35 cm in length and 1cm width. The experiments were done with the similar uniaxial loading configuration to Rosakis et al. (2007). Axial load σ is applied to the fault plane with an angle 60° to the loading direction. When σ is 5kN, normal and shear stresses on the fault are 1.25MPa and 0.72MPa, respectively. Timing and direction of slip propagation on the fault during the experiments were monitored with several strain gauges arrayed at an interval along the fault. The gauge data were digitally recorded with a 1MHz sampling rate and 16bit resolution. When σ is 4.8kN is applied, we observed some fault slip events where a slip nucleates spontaneously in a subsection of the fault and propagates to the whole fault. However, the propagation speed is about 1.2km/s, much lower than the S-wave velocity of the rock. This indicates that the slip events were not earthquake-like dynamic rupture ones. More efforts are needed to reproduce earthquake-like slip events in the experiments. This work is supported by the JSPS KAKENHI (26870912).

  14. Characterization of slow slip rate faults in humid areas: Cimandiri fault zone, Indonesia

    NASA Astrophysics Data System (ADS)

    Marliyani, G. I.; Arrowsmith, J. R.; Whipple, K. X.

    2016-12-01

    In areas where regional tectonic 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 or soils; their geomorphic expression subdued and sometimes undetectable until the next earthquake. In Java, active faults are diffused, and their characterization is challenging. Among them is the ENE striking Cimandiri fault zone. Cumulative displacement produces prominent ENE oriented ranges with the southeast side moving relatively upward and to the northeast. The fault zone is expressed in the bedrock by numerous NE, west, and NW trending thrust- and strike-slip faults and folds. However, it is unclear which of these structures are active. We performed a morphometric analysis of the fault zone using 30 m resolution Shuttle Radar Topography Mission digital elevation model. We constructed longitudinal profiles of 601 bedrock rivers along the upthrown ranges along the fault zone, calculated the normalized channel steepness index, identified knickpoints and use their distribution to infer relative magnitudes of rock uplift and locate boundaries that may indicate active fault traces. We compare the rock uplift distribution to surface displacement predicted by elastic dislocation model to determine the plausible fault kinematics. The active Cimandiri fault zone consists of six segments with predominant sense of reverse motion. Our analysis reveals considerable geometric complexity, strongly suggesting segmentation of the fault, and thus smaller maximum earthquakes, consistent with the limited historical record of upper plate earthquakes in Java.

  15. Data fault detection in medical sensor networks.

    PubMed

    Yang, Yang; Liu, Qian; Gao, Zhipeng; Qiu, Xuesong; Meng, Luoming

    2015-03-12

    Medical body sensors can be implanted or attached to the human body to monitor the physiological parameters of patients all the time. Inaccurate data due to sensor faults or incorrect placement on the body will seriously influence clinicians' diagnosis, therefore detecting sensor data faults has been widely researched in recent years. Most of the typical approaches to sensor fault detection in the medical area ignore the fact that the physiological indexes of patients aren't changing synchronously at the same time, and fault values mixed with abnormal physiological data due to illness make it difficult to determine true faults. Based on these facts, we propose a Data Fault Detection mechanism in Medical sensor networks (DFD-M). Its mechanism includes: (1) use of a dynamic-local outlier factor (D-LOF) algorithm to identify outlying sensed data vectors; (2) use of a linear regression model based on trapezoidal fuzzy numbers to predict which readings in the outlying data vector are suspected to be faulty; (3) the proposal of a novel judgment criterion of fault state according to the prediction values. The simulation results demonstrate the efficiency and superiority of DFD-M.

  16. Formal Validation of Fault Management Design Solutions

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  17. On-line diagnosis of unrestricted faults

    NASA Technical Reports Server (NTRS)

    Meyer, J. F.; Sundstrom, R. J.

    1974-01-01

    A formal model for the study of on-line diagnosis is introduced and used to investigate the diagnosis of unrestricted faults. A fault of a system S is considered to be a transformation of S into another system S' at some time tau. The resulting faulty system is taken to be the system which looks like S up to time tau, and like S' thereafter. Notions of fault tolerance error are defined in terms of the resulting system being able to mimic some desired behavior as specified by a system similar to S. A notion of on-line diagnosis is formulated which involves an external detector and a maximum time delay within which every error caused by a fault in a prescribed set must be detected. It is shown that if a system is on-line diagnosable for the unrestricted set of faults then the detector is at least as complex, in terms of state set size, as the specification. The use of inverse systems for the diagnosis of unrestricted faults is considered. A partial characterization of those inverses which can be used for unrestricted fault diagnosis is obtained.

  18. Extension and contraction of faulted marker planes

    NASA Astrophysics Data System (ADS)

    Jackson, Marie D.; Delaney, Paul T.

    1985-08-01

    We present graphical and analytical methods to determine the extensional or contractional separation of a faulted planar marker using commonly measured field data: fault attitude, slip direction, and bedding or other marker-plane attitude. This determination is easily accomplished for horizontal markers. Faults with normal components of slip extend the markers and indicate extensional tectonics; those with reverse components are contractional. Although the methods quantify this simple relation for horizontal markers, they are most useful in rocks with planar fabrics of steep dip where marker separation cannot be uniquely determined from map or outcrop patterns alone and where faults with normal components of dip slip can contract markers and those with reverse components can extend them. The methods rely on two parameters: (1) the angle between normals to the marker and fault planes and (2) the angle between the slip direction and intersection of the marker and fault. This second parameter measures the obliquity of slip relative to the directions of maximum extensional or contractional separation of the marker, and for a horizontal marker, it is equivalent to the rake of the slip direction. The graphical method requires stereographic projections routinely used for faulting data; the analytical method is programmable on a calculator. *Present address: Department of Applied Earth Sciences, Stanford University, Stanford, California 94035

  19. The mechanics of gravity-driven faulting

    NASA Astrophysics Data System (ADS)

    Barrows, L.; Barrows, V.

    2010-04-01

    Faulting can result from either of two different mechanisms. These involve fundamentally different energetics. In elastic rebound, locked-in elastic strain energy is transformed into the earthquake (seismic waves plus work done in the fault zone). In force-driven faulting, the forces that create the stress on the fault supply work or energy to the faulting process. Half of this energy is transformed into the earthquake and half goes into an increase in locked-in elastic strain. In elastic rebound the locked-in elastic strain drives slip on the fault. In force-driven faulting it stops slip on the fault. Tectonic stress is reasonably attributed to gravity acting on topography and the Earth's lateral density variations. This includes the thermal convection that ultimately drives plate tectonics. Mechanical analysis has shown the intensity of the gravitational tectonic stress that is associated with the regional topography and lateral density variations that actually exist is comparable with the stress drops that are commonly associated with tectonic earthquakes; both are in the range of tens of bar to several hundred bar. The gravity collapse seismic mechanism assumes the fault fails and slips in direct response to the gravitational tectonic stress. Gravity collapse is an example of force-driven faulting. In the simplest case, energy that is released from the gravitational potential of the stress-causing topography and lateral density variations is equally split between the earthquake and the increase in locked-in elastic strain. The release of gravitational potential energy requires a change in the Earth's density distribution. Gravitational body forces are solely dependent on density so a change in the density distribution requires a change in the body forces. This implies the existence of volumetric body-force displacements. The volumetric body-force displacements are in addition to displacements generated by slip on the fault. They must exist if gravity

  20. Tunable architecture for aircraft fault detection

    NASA Technical Reports Server (NTRS)

    Ganguli, Subhabrata (Inventor); Papageorgiou, George (Inventor); Glavaski-Radovanovic, Sonja (Inventor)

    2012-01-01

    A method for detecting faults in an aircraft is disclosed. The method involves predicting at least one state of the aircraft and tuning at least one threshold value to tightly upper bound the size of a mismatch between the at least one predicted state and a corresponding actual state of the non-faulted aircraft. If the mismatch between the at least one predicted state and the corresponding actual state is greater than or equal to the at least one threshold value, the method indicates that at least one fault has been detected.

  1. Cooperative human-machine fault diagnosis

    NASA Technical Reports Server (NTRS)

    Remington, Roger; Palmer, Everett

    1987-01-01

    Current expert system technology does not permit complete automatic fault diagnosis; significant levels of human intervention are still required. This requirement dictates a need for a division of labor that recognizes the strengths and weaknesses of both human and machine diagnostic skills. Relevant findings from the literature on human cognition are combined with the results of reviews of aircrew performance with highly automated systems to suggest how the interface of a fault diagnostic expert system can be designed to assist human operators in verifying machine diagnoses and guiding interactive fault diagnosis. It is argued that the needs of the human operator should play an important role in the design of the knowledge base.

  2. Cooperative Human-Machine Fault Diagnosis

    NASA Astrophysics Data System (ADS)

    Remington, Roger; Palmer, Everett

    1987-02-01

    Current expert system technology does not permit complete automatic fault diagnosis; significant levels of human intervention are still required. This requirement dictates a need for a division of labor that recognizes the strengths and weaknesses of both human and machine diagnostic skills. Relevant findings from the literature on human cognition are combined with the results of reviews of aircrew performance with highly automated systems to suggest how the interface of a fault diagnostic expert system can be designed to assist human operators in verifying machine diagnoses and guiding interactive fault diagnosis. It is argued that the needs of the human operator should play an important role in the design of the knowledge base.

  3. An aircraft sensor fault tolerant system

    NASA Technical Reports Server (NTRS)

    Caglayan, A. K.; Lancraft, R. E.

    1982-01-01

    The design of a sensor fault tolerant system which uses analytical redundancy for the Terminal Configured Vehicle (TCV) research aircraft in a Microwave Landing System (MLS) environment was studied. The fault tolerant system provides reliable estimates for aircraft position, velocity, and attitude in the presence of possible failures in navigation aid instruments and onboard sensors. The estimates, provided by the fault tolerant system, are used by the automated guidance and control system to land the aircraft along a prescribed path. Sensor failures are identified by utilizing the analytic relationship between the various sensor outputs arising from the aircraft equations of motion.

  4. The San Andreas Fault System, California

    USGS Publications Warehouse

    Wallace, Robert E.

    1990-01-01

    Maps of northern and southern California printed on flyleaf inside front cover and on adjacent pages show faults that have had displacement within the past 2 million years. Those that have had displacement within historical time are shown in red. Bands of red tint emphasize zones of historical displacement; bands of orange tint emphasize major faults that have had Quaternary displacement before historical time. Faults are dashed where uncertain, dotted where covered by sedimentary deposits, and queried when doubtful. Arrows indicate direction of relative movement; sawteeth on upper plate of thrust fault. These maps are reproductions, in major part, of selected plates from the "Fault Map of California," published in 1975 by the California Division of Mines and Geology at a scale of 1:750,000; the State map was compiled and data interpreted by Charles W. Jennings. New data about faults, not shown on the 1975 edition, required modest revisions, primarily additions however, most of the map was left unchanged because the California Division of Mines and Geology is currently engaged in a major revision and update of the 1975 edition. Because of the reduced scale here, names of faults and places were redrafted or omitted. Faults added to the reduced map are not as precise as on the original State map, and the editor of this volume selected certain faults and omitted others. Principal regions for which new information was added are the region north of the San Francisco Bay area and the offshore regions.Many people have contributed to the present map, but the editor is solely responsible for any errors and omissions. Among those contributing informally, but extensively, and the regions to which each contributed were G.A. Carver, onland region north of lat 40°N.; S.H. Clarke, offshore region north of Cape Mendocino; R.J. McLaughlin, onland region between lat 40°00' and 40°30' N. and long 123°30' and 124°30' W.; D.S. McCulloch offshore region between lat 35° and 40° N

  5. Geofluid Dynamics of Faulted Sedimentary Basins

    NASA Astrophysics Data System (ADS)

    Garven, G.; Jung, B.; Boles, J. R.

    2014-12-01

    Faults are known to affect basin-scale groundwater flow, and exert a profound control on petroleum migration/accumulation, the PVT-history of hydrothermal fluids, and the natural (submarine) seepage from offshore reservoirs. For example, in the Santa Barbara basin, measured gas flow data from a natural submarine seep area in the Santa Barbara Channel helps constrain fault permeability k ~ 30 millidarcys for the large-scale upward migration of methane-bearing formation fluids along one of the major fault zones. At another offshore site near Platform Holly, pressure-transducer time-series data from a 1.5 km deep exploration well in the South Ellwood Field demonstrate a strong ocean tidal component, due to vertical fault connectivity to the seafloor. Analytical solutions to the poroelastic flow equation can be used to extract both fault permeability and compressibility parameters, based on tidal-signal amplitude attenuation and phase shift at depth. These data have proven useful in constraining coupled hydrogeologic 2-D models for reactive flow and geomechanical deformation. In a similar vein, our studies of faults in the Los Angeles basin, suggest an important role for the natural retention of fluids along the Newport-Inglewood fault zone. Based on the estimates of fault permeability derived above, we have also constructed new two-dimensional numerical simulations to characterize large-scale multiphase flow in complex heterogeneous and anisotropic geologic profiles, such as the Los Angeles basin. The numerical model was developed in our lab at Tufts from scratch, and based on an IMPES-type algorithm for a finite element/volume mesh. This numerical approach allowed us model large differentials in fluid saturation and relative permeability, caused by complex geological heterogeneities associated with sedimentation and faulting. Our two-phase flow models also replicated the formation-scale patterns of petroleum accumulation associated with the basin margin, where deep

  6. Cooperative application/OS DRAM fault recovery.

    SciTech Connect

    Ferreira, Kurt Brian; Bridges, Patrick G.; Heroux, Michael Allen; Hoemmen, Mark; Brightwell, Ronald Brian

    2012-05-01

    Exascale systems will present considerable fault-tolerance challenges to applications and system software. These systems are expected to suffer several hard and soft errors per day. Unfortunately, many fault-tolerance methods in use, such as rollback recovery, are unsuitable for many expected errors, for example DRAM failures. As a result, applications will need to address these resilience challenges to more effectively utilize future systems. In this paper, we describe work on a cross-layer application/OS framework to handle uncorrected memory errors. We illustrate the use of this framework through its integration with a new fault-tolerant iterative solver within the Trilinos library, and present initial convergence results.

  7. Mechanical Models of Fault-Related Folding

    SciTech Connect

    Johnson, A. M.

    2003-01-09

    The subject of the proposed research is fault-related folding and ground deformation. The results are relevant to oil-producing structures throughout the world, to understanding of damage that has been observed along and near earthquake ruptures, and to earthquake-producing structures in California and other tectonically-active areas. The objectives of the proposed research were to provide both a unified, mechanical infrastructure for studies of fault-related foldings and to present the results in computer programs that have graphical users interfaces (GUIs) so that structural geologists and geophysicists can model a wide variety of fault-related folds (FaRFs).

  8. Fault tolerance and testing for WSI systems

    NASA Astrophysics Data System (ADS)

    Ptak, Alan W.; McLeod, R. D.

    Fault tolerance and testing for wafer scale integration (WSI) processor arrays using boundary scan and built-in self-test (BIST) technology are discussed. A test strategy for verification of all components within an integrated circuit wafer is presented, and a fault tolerance technique using semi-concurrent fault detection is described. The test strategy consists of four steps taken to verify test bus continuity, boundary scan register continuity, interconnection network connectivity, and processor element integrity. The component-level area overhead for boundary scan and BIST is modest for present-day fabrication processes, and will diminish to an insignificant level as integrated circuit fabrication technology continues to improve.

  9. Efficient fault diagnosis of helicopter gearboxes

    NASA Technical Reports Server (NTRS)

    Chin, H.; Danai, K.; Lewicki, D. G.

    1993-01-01

    Application of a diagnostic system to a helicopter gearbox is presented. The diagnostic system is a nonparametric pattern classifier that uses a multi-valued influence matrix (MVIM) as its diagnostic model and benefits from a fast learning algorithm that enables it to estimate its diagnostic model from a small number of measurement-fault data. To test this diagnostic system, vibration measurements were collected from a helicopter gearbox test stand during accelerated fatigue tests and at various fault instances. The diagnostic results indicate that the MVIM system can accurately detect and diagnose various gearbox faults so long as they are included in training.

  10. Negative Selection Algorithm for Aircraft Fault Detection

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    We investigated a real-valued Negative Selection Algorithm (NSA) for fault detection in man-in-the-loop aircraft operation. The detection algorithm uses body-axes angular rate sensory data exhibiting the normal flight behavior patterns, to generate probabilistically a set of fault detectors that can detect any abnormalities (including faults and damages) in the behavior pattern of the aircraft flight. We performed experiments with datasets (collected under normal and various simulated failure conditions) using the NASA Ames man-in-the-loop high-fidelity C-17 flight simulator. The paper provides results of experiments with different datasets representing various failure conditions.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    Fault surface roughness is a principal factor influencing fault and earthquake mechanics. However, little is known on roughness of fault surfaces at seismogenic depths, and particularly on how it evolves with accumulating slip. We have studied seismogenic fault surfaces of the Gole Larghe Fault Zone, which exploit precursor cooling joints of the Adamello tonalitic pluton (Italian Alps). These faults developed at 9-11 km and 250-300°C. Seismic slip along these surfaces, which individually accommodated from 1 to 20 m of net slip, resulted in the production of cm-thick cataclasites and pseudotachylytes (solidified melts produced during seismic slip). The roughness of fault surfaces was determined with a multi-resolution aerial and terrestrial LIDAR and photogrammetric dataset (Bistacchi et al., 2011, Pageoph, doi: 10.1007/s00024-011-0301-7). Fault surface roughness is self-affine, with Hurst exponent H < 1, indicating that faults are comparatively smoother at larger wavelengths. Fault surface roughness is inferred to have been inherited from the precursor cooling joints, which show H ≈ 0.8. Slip on faults progressively modified the roughness distribution, lowering the Hurst exponent in the along-slip direction up to H ≈ 0.6. This behaviour has been observed for wavelengths up to the scale of the accumulated slip along each individual fault surface, whilst at larger wavelengths the original roughness seems not to be affected by slip. Processes that contribute to modify fault roughness with slip include brittle failure of the interacting asperities (production of cataclasites) and frictional melting (production of pseudotachylytes). To quantify the "wear" due to these processes, we measured, together with the roughness of fault traces and their net slip, the thickness and distribution of cataclasites and pseudotachylytes. As proposed also in the tribological literature, we observe that wearing is scale dependent, as smaller wavelength asperities have a shorter

  12. Physical and Mechanical Properties of the Mozumi Fault, Japan: Petrophysics of a Fine-Grained Fault Zone

    NASA Astrophysics Data System (ADS)

    Isaacs, A. J.; Evans, J. P.; Kolesar, P. T.

    2005-12-01

    The Mozumi-Sokenobu fault, a right-lateral strike-slip fault in north-central Honshu, Japan is intersected by the Active Fault Survey Tunnel. This tunnel allows for direct observation of the fault at a depth of 300-400 m below the ground surface. Within the tunnel, the Mozumi fault cuts Jurassic Tetori Group sandstone and shale. We have characterized microstructures, mineralogy, geochemistry, and elastic properties of fault rock samples from the Mozumi fault. These data can be combined to illustrate the in-situ macroscopic hydro-mechanical structure of the fault. Core samples from the main Mozumi fault zone intersected by the Active Fault Survey Tunnel borehole A were analyzed and compared to wireline logs for a petrophysical study of the fault zone rocks. Microstructures, mineralogy, and geochemistry of Mozumi fault rocks indicate syn-tectonic fluid flow and multiple deformation events. Resistivity and sonic log values are depressed through the main fault zone. Likewise, the seismic p and s wave velocity values are decreased across the main fault relative to the surrounding rock. Calculated values for Young's modulus and Poisson's ratio fall at the top of or above the experimentally derived range for elastic moduli of siltstone, shale, and sandstone. Smaller scale variations across the fault zone itself are also present. Samples of foliated fault rocks containing predominantly muscovite have intermediate values for elastic moduli and seismic velocity relative to other fault zone samples used in this study. Fault rocks significantly depleted in oxides relative to host rock samples and containing mixed clays have higher resistivity than surrounding fault rocks and intermediate permeability values. These variations in physical and mechanical properties throughout the fault zone coincide with the complex fault-parallel combined conduit/barrier permeability structure of the Mozumi fault zone.

  13. Bayesian network based on a fault tree and its application in diesel engine fault diagnosis

    NASA Astrophysics Data System (ADS)

    Qian, Gang; Zheng, Shengguo; Cao, Longhan

    2005-12-01

    This paper discusses the faults diagnosis of diesel engine systems. This research aims at the optimization of the diagnosis results. Inspired by Bayesian Network (BN) possessing good performance in solving uncertainty problems, a new method was proposed for establishing a BN of diesel engine faults quickly, and diagnosing faults exactly. This method consisted of two stages,namely the establishment of a BN model, and a faults diagnosis of the diesel engine system using that BN mode. For the purpose of establishing the BN, a new algorithm, which can establish a BN quickly and easily, is presented. The Fault Tree (FT) diagnosis model of the diesel engine system was established first. Then it was transformed it into a BN by using our algorithm. Finally, the BN was used to diagnose the faults of a diesel engine system. Experimental results show that the diagnosis speed is increased and the accuracy is improved.

  14. Late quaternary faulting along the Death Valley-Furnace Creek fault system, California and Nevada

    SciTech Connect

    Brogan, G.E.; Kellogg, K.S.; Terhune, C.L.; Slemmons, D.B.

    1991-12-31

    The Death Valley-Furnace Creek fault system, in California and Nevada, has a variety of impressive late Quaternary neotectonic features that record a long history of recurrent earthquake-induced faulting. Although no neotectonic features of unequivocal historical age are known, paleoseismic features from multiple late Quaternary events of surface faulting are well developed throughout the length of the system. Comparison of scarp heights to amount of horizontal offset of stream channels and the relationships of both scarps and channels to the ages of different geomorphic surfaces demonstrate that Quaternary faulting along the northwest-trending Furnace Creek fault zone is predominantly right lateral, whereas that along the north-trending Death Valley fault zone is predominantly normal. These observations are compatible with tectonic models of Death Valley as a northwest- trending pull-apart basin.

  15. Data-based fault-tolerant control for affine nonlinear systems with actuator faults.

    PubMed

    Xie, Chun-Hua; Yang, Guang-Hong

    2016-09-01

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

  16. Fault Rock Variation as a Function of Host Rock Lithology

    NASA Astrophysics Data System (ADS)

    Fagereng, A.; Diener, J.

    2013-12-01

    Fault rocks contain an integrated record of the slip history of a fault, and thereby reflect the deformation processes associated with fault slip. Within the Aus Granulite Terrane, Namibia, a number of Jurassic to Cretaceous age strike-slip faults cross-cut Precambrian high grade metamorphic rocks. These strike-slip faults were active at subgreenschist conditions and occur in a variety of host rock lithologies. Where the host rock contains significant amounts of hydrous minerals, representing granulites that have undergone retrogressive metamorphism, the fault rock is dominated by hydrothermal breccias. In anhydrous, foliated rocks interlayered with minor layers containing hydrous phyllosilicates, the fault rock is a cataclasite partially cemented by jasper and quartz. Where the host rock is an isotropic granitic rock the fault rock is predominantly a fine grained black fault rock. Cataclasites and breccias show evidence for multiple deformation events, whereas the fine grained black fault rocks appear to only record a single slip increment. The strike-slip faults observed all formed in the same general orientation and at a similar time, and it is unlikely that regional stress, strain rate, pressure and temperature varied between the different faults. We therefore conclude that the type of fault rock here depended on the host rock lithology, and that lithology alone accounts for why some faults developed a hydrothermal breccia, some cataclasite, and some a fine grained black fault rock. Consequently, based on the assumption that fault rocks reflect specific slip styles, lithology was also the main control on different fault slip styles in this area at the time of strike-slip fault activity. Whereas fine grained black fault rock is inferred to represent high stress events, hydrothermal breccia is rather related to events involving fluid pressure in excess of the least stress. Jasper-bearing cataclasites may represent faults that experienced dynamic weakening as seen

  17. Geometry and earthquake potential of the shoreline fault, central California

    USGS Publications Warehouse

    Hardebeck, Jeanne L.

    2013-01-01

    The Shoreline fault is a vertical strike‐slip fault running along the coastline near San Luis Obispo, California. Much is unknown about the Shoreline fault, including its slip rate and the details of its geometry. Here, I study the geometry of the Shoreline fault at seismogenic depth, as well as the adjacent section of the offshore Hosgri fault, using seismicity relocations and earthquake focal mechanisms. The Optimal Anisotropic Dynamic Clustering (OADC) algorithm (Ouillon et al., 2008) is used to objectively identify the simplest planar fault geometry that fits all of the earthquakes to within their location uncertainty. The OADC results show that the Shoreline fault is a single continuous structure that connects to the Hosgri fault. Discontinuities smaller than about 1 km may be undetected, but would be too small to be barriers to earthquake rupture. The Hosgri fault dips steeply to the east, while the Shoreline fault is essentially vertical, so the Hosgri fault dips towards and under the Shoreline fault as the two faults approach their intersection. The focal mechanisms generally agree with pure right‐lateral strike‐slip on the OADC planes, but suggest a non‐planar Hosgri fault or another structure underlying the northern Shoreline fault. The Shoreline fault most likely transfers strike‐slip motion between the Hosgri fault and other faults of the Pacific–North America plate boundary system to the east. A hypothetical earthquake rupturing the entire known length of the Shoreline fault would have a moment magnitude of 6.4–6.8. A hypothetical earthquake rupturing the Shoreline fault and the section of the Hosgri fault north of the Hosgri–Shoreline junction would have a moment magnitude of 7.2–7.5.

  18. A Hybrid Approach for Fault Detection in Autonomous Physical Agents

    DTIC Science & Technology

    2014-05-01

    A Hybrid Approach for Fault Detection in Autonomous Physical Agents Eliahu Khalastchi, Meir Kalech, Lior Rokach Information Systems Engineering...Experimentation Keywords Fault detection, Model-Based Diagnosis , Robotics, UAV. 1. INTRODUCTION Autonomous physical agents such as Unmanned Vehicles (UVs...then a crash. To continue operate autonomously, the agent must have an accurate fault detection mechanism. Upon fault detection a diagnosis process

  19. Influence of mechanical stratigraphy and kinematics on fault scaling relations

    NASA Astrophysics Data System (ADS)

    Gross, Michael R.; G´rrez-Alonso, Gabriel; Bai, Taixu; Wacker, Michael A.; Collinsworth, Kevin B.; Behl, Richard J.

    1997-02-01

    In order to document effects of mechanical anisotropy, fault geometry, and structural style on displacement-length ( D-L) scaling relations, we investigated fault dimensions in the lithologically heterogeneous Monterey Formation exposed along Arroyo Burro Beach, California. The faults, which range in length from several centimeters to several meters, group into two populations: small faults confined to individual mudstone beds, and larger faults that displace multiple beds and often merge into bedding plane detachments. Whereas a linear correlation exists between displacement and length for small faults, displacement across large faults is independent of length. We attribute this deviation from scale-invariance to a combination of geologic factors that influence fault growth once faults extend beyond the confines of mudstone beds. Propagation of large faults across higher moduli opal-CT porcellanite leads to a reduction in DL, as does the development of drag folds. Further scatter in DL occurs when fault tips splay as they approach detachments. Large faults eventually merge into bedding plane detachments, which originally formed due to flexural slip folding. Extremely high DL ratios are recorded for these merged faults as they accommodate block rotation within a simple shear zone. Thus, both mechanical stratigraphy and the temporal evolution of fault systems can lead to a breakdown in fault scaling relations thought to characterize isolated fault growth in a homogeneous medium.

  20. PV Systems Reliability Final Technical Report: Ground Fault Detection

    SciTech Connect

    Lavrova, Olga; Flicker, Jack David; Johnson, Jay

    2016-01-01

    We have examined ground faults in PhotoVoltaic (PV) arrays and the efficacy of fuse, current detection (RCD), current sense monitoring/relays (CSM), isolation/insulation (Riso) monitoring, and Ground Fault Detection and Isolation (GFID) using simulations based on a Simulation Program with Integrated Circuit Emphasis SPICE ground fault circuit model, experimental ground faults installed on real arrays, and theoretical equations.

  1. Network Connectivity for Permanent, Transient, Independent, and Correlated Faults

    NASA Technical Reports Server (NTRS)

    White, Allan L.; Sicher, Courtney; henry, Courtney

    2012-01-01

    This paper develops a method for the quantitative analysis of network connectivity in the presence of both permanent and transient faults. Even though transient noise is considered a common occurrence in networks, a survey of the literature reveals an emphasis on permanent faults. Transient faults introduce a time element into the analysis of network reliability. With permanent faults it is sufficient to consider the faults that have accumulated by the end of the operating period. With transient faults the arrival and recovery time must be included. The number and location of faults in the system is a dynamic variable. Transient faults also introduce system recovery into the analysis. The goal is the quantitative assessment of network connectivity in the presence of both permanent and transient faults. The approach is to construct a global model that includes all classes of faults: permanent, transient, independent, and correlated. A theorem is derived about this model that give distributions for (1) the number of fault occurrences, (2) the type of fault occurrence, (3) the time of the fault occurrences, and (4) the location of the fault occurrence. These results are applied to compare and contrast the connectivity of different network architectures in the presence of permanent, transient, independent, and correlated faults. The examples below use a Monte Carlo simulation, but the theorem mentioned above could be used to guide fault-injections in a laboratory.

  2. Misbheaving Faults: The Expanding Role of Geodetic Imaging in Unraveling Unexpected Fault Slip Behavior

    NASA Astrophysics Data System (ADS)

    Barnhart, W. D.; Briggs, R.

    2015-12-01

    Geodetic imaging techniques enable researchers to "see" details of fault rupture that cannot be captured by complementary tools such as seismology and field studies, thus providing increasingly detailed information about surface strain, slip kinematics, and how an earthquake may be transcribed into the geological record. For example, the recent Haiti, Sierra El Mayor, and Nepal earthquakes illustrate the fundamental role of geodetic observations in recording blind ruptures where purely geological and seismological studies provided incomplete views of rupture kinematics. Traditional earthquake hazard analyses typically rely on sparse paleoseismic observations and incomplete mapping, simple assumptions of slip kinematics from Andersonian faulting, and earthquake analogs to characterize the probabilities of forthcoming ruptures and the severity of ground accelerations. Spatially dense geodetic observations in turn help to identify where these prevailing assumptions regarding fault behavior break down and highlight new and unexpected kinematic slip behavior. Here, we focus on three key contributions of space geodetic observations to the analysis of co-seismic deformation: identifying near-surface co-seismic slip where no easily recognized fault rupture exists; discerning non-Andersonian faulting styles; and quantifying distributed, off-fault deformation. The 2013 Balochistan strike slip earthquake in Pakistan illuminates how space geodesy precisely images non-Andersonian behavior and off-fault deformation. Through analysis of high-resolution optical imagery and DEMs, evidence emerges that a single fault map slip as both a strike slip and dip slip fault across multiple seismic cycles. These observations likewise enable us to quantify on-fault deformation, which account for ~72% of the displacements in this earthquake. Nonetheless, the spatial distribution of on- and off-fault deformation in this event is highly spatially variable- a complicating factor for comparisons

  3. Quaternary Geology and Surface Faulting Hazard: Active and Capable Faults in Central Apennines, Italy

    NASA Astrophysics Data System (ADS)

    Falcucci, E.; Gori, S.

    2015-12-01

    The 2009 L'Aquila earthquake (Mw 6.1), in central Italy, raised the issue of surface faulting hazard in Italy, since large urban areas were affected by surface displacement along the causative structure, the Paganica fault. Since then, guidelines for microzonation were drew up that take into consideration the problem of surface faulting in Italy, and laying the bases for future regulations about related hazard, similarly to other countries (e.g. USA). More specific guidelines on the management of areas affected by active and capable faults (i.e. able to produce surface faulting) are going to be released by National Department of Civil Protection; these would define zonation of areas affected by active and capable faults, with prescriptions for land use planning. As such, the guidelines arise the problem of the time interval and general operational criteria to asses fault capability for the Italian territory. As for the chronology, the review of the international literature and regulatory allowed Galadini et al. (2012) to propose different time intervals depending on the ongoing tectonic regime - compressive or extensional - which encompass the Quaternary. As for the operational criteria, the detailed analysis of the large amount of works dealing with active faulting in Italy shows that investigations exclusively based on surface morphological features (e.g. fault planes exposition) or on indirect investigations (geophysical data), are not sufficient or even unreliable to define the presence of an active and capable fault; instead, more accurate geological information on the Quaternary space-time evolution of the areas affected by such tectonic structures is needed. A test area for which active and capable faults can be first mapped based on such a classical but still effective methodological approach can be the central Apennines. Reference Galadini F., Falcucci E., Galli P., Giaccio B., Gori S., Messina P., Moro M., Saroli M., Scardia G., Sposato A. (2012). Time

  4. Fault zone Q values derived from Taiwan Chelungpu Fault borehole seismometers (TCDPBHS)

    NASA Astrophysics Data System (ADS)

    Wang, Yu-Ju; Lin, Yen-Yu; Lee, Meng-Chieh; Ma, Kuo-Fong

    2012-11-01

    The attenuation factor, Q, at a fault zone is an important parameter for understanding the physical properties. In this study, we investigated the Q value of the Chelungpu Fault, the main rupture of the Mw 7.6 Chi-Chi earthquake, using the 7-level TCDP borehole seismometer array (TCDPBHS). The TCDPBHS was deployed at depths from 945 to 1270 m throughout the 1999 ruptured slip zone at 1111 m. Three borehole seismometers (BHS1-BHS3) were placed in the hanging wall, and the remaining three (BHS5-BHS7) were placed in the foot wall, with BHS4 near the slip zone. The configuration allowed us to estimate the Q-structure of the recent ruptured fault zone. In this study, we estimated Q values between BHS1 and BHS4, Qs1 (Qp1) at the fault zone and between BHS4 to 2 km in depth, Qs4 (Qp4) beneath the fault zone. We utilized two independent methods, the spectral ratio and spectral fitting analyses, for calculating the Q value of Qs1 (Qp1) in order to provide a reliability check. After analyzing 26 micro-events for Qs and 17 micro-events for Qp, we obtained consistent Q values from the two independent methods. The values of Qs1 and Qp1 were 21-22 and 27-35, respectively. The investigation for the value of Qs4 was close to 45, and Qp4 was 85. These Qp and Qs values are quiet consistent with observations obtained for the San Andreas Fault at the corresponding depth. A low Qs1 value for the recent Chelungpu Fault zone suggests that this fault zone has been highly fractured. Qs values within the Chelungpu Fault, similar to those within the San Andreas Fault, suggest that the Q structure within the fault zone is sedimentary rock independent. However, the possible existence of fluids, fractures, and cracks dominates the attenuation feature in the fault zone.

  5. Parameter Transient Behavior Analysis on Fault Tolerant Control System

    NASA Technical Reports Server (NTRS)

    Belcastro, Christine (Technical Monitor); Shin, Jong-Yeob

    2003-01-01

    In a fault tolerant control (FTC) system, a parameter varying FTC law is reconfigured based on fault parameters estimated by fault detection and isolation (FDI) modules. FDI modules require some time to detect fault occurrences in aero-vehicle dynamics. This paper illustrates analysis of a FTC system based on estimated fault parameter transient behavior which may include false fault detections during a short time interval. Using Lyapunov function analysis, the upper bound of an induced-L2 norm of the FTC system performance is calculated as a function of a fault detection time and the exponential decay rate of the Lyapunov function.

  6. GIS coverages of the Castle Mountain Fault, south central Alaska

    USGS Publications Warehouse

    Labay, Keith A.; Haeussler, Peter J.

    2001-01-01

    The Castle Mountain fault is one of several major east-northeast-striking faults in southern Alaska, and it is the only fault with had historic seismicity and Holocene surface faulting. This report is a digital compilation of three maps along the Castle Mountain fault in south central Alaska. This compilation consists only of GIS coverages of the location of the fault, line attributes indicating the certainty of the fault location, and information about scarp height, where measured. The files are presented in ARC/INFO export file format and include metadata.

  7. Inspection and rehabilitation of tunnels across faults

    SciTech Connect

    Abramson, L.W.; Schmidt, B.

    1995-12-31

    The inspection and rehabilitation of tunnels that cross faults is unique because they usually are in use and have a large variety of alternative lining types including bare rock, concrete, or steel often coated with accumulations of dirt, grime, algae and other minerals. Inspection methods are important including what to look for, how to clean the inner tunnel lining surfaces, non-destructive testing, coring, soundings, air quality detection and protection, ventilation, lightning, etc. Rehabilitation of tunnels crossing faults requires a practiced knowledge of underground design and construction practices. The most common methods of rehabilitation include grouting and concreting. The Variety of water, wastewater, transit, and highway tunnels in California provide ample examples of tunnels, new and old, that cross active faults. This paper will address specific methods of tunnel inspection and maintenance at fault crossings and give examples of relevant highway, transit, water, and wastewater projects and studies in California to demonstrate the discussions presented.

  8. Current Sensor Fault Reconstruction for PMSM Drives.

    PubMed

    Huang, Gang; Luo, Yi-Ping; Zhang, Chang-Fan; He, Jing; Huang, Yi-Shan

    2016-01-30

    This paper deals with a current sensor fault reconstruction algorithm for the torque closed-loop drive system of an interior PMSM. First, sensor faults are equated to actuator ones by a new introduced state variable. Then, in αβ coordinates, based on the motor model with active flux linkage, a current observer is constructed with a specific sliding mode equivalent control methodology to eliminate the effects of unknown disturbances, and the phase current sensor faults are reconstructed by means of an adaptive method. Finally, an αβ axis current fault processing module is designed based on the reconstructed value. The feasibility and effectiveness of the proposed method are verified by simulation and experimental tests on the RT-LAB platform.

  9. Current Sensor Fault Reconstruction for PMSM Drives

    PubMed Central

    Huang, Gang; Luo, Yi-Ping; Zhang, Chang-Fan; He, Jing; Huang, Yi-Shan

    2016-01-01

    This paper deals with a current sensor fault reconstruction algorithm for the torque closed-loop drive system of an interior PMSM. First, sensor faults are equated to actuator ones by a new introduced state variable. Then, in αβ coordinates, based on the motor model with active flux linkage, a current observer is constructed with a specific sliding mode equivalent control methodology to eliminate the effects of unknown disturbances, and the phase current sensor faults are reconstructed by means of an adaptive method. Finally, an αβ axis current fault processing module is designed based on the reconstructed value. The feasibility and effectiveness of the proposed method are verified by simulation and experimental tests on the RT-LAB platform. PMID:26840317

  10. Study of fault-tolerant software technology

    NASA Technical Reports Server (NTRS)

    Slivinski, T.; Broglio, C.; Wild, C.; Goldberg, J.; Levitt, K.; Hitt, E.; Webb, J.

    1984-01-01

    Presented is an overview of the current state of the art of fault-tolerant software and an analysis of quantitative techniques and models developed to assess its impact. It examines research efforts as well as experience gained from commercial application of these techniques. The paper also addresses the computer architecture and design implications on hardware, operating systems and programming languages (including Ada) of using fault-tolerant software in real-time aerospace applications. It concludes that fault-tolerant software has progressed beyond the pure research state. The paper also finds that, although not perfectly matched, newer architectural and language capabilities provide many of the notations and functions needed to effectively and efficiently implement software fault-tolerance.

  11. Continuous reconfiguration: fault tolerance without a ripple

    SciTech Connect

    Bortner, R.A.

    1983-01-01

    The concepts of the continuously reconfiguring flight control system (crm/sup 2/fcs) and the impact of its architecture upon fault tolerance and reliability are covered. Some of the topics discussed are continuous reconfiguration, autonomous control, virtual common memory and the fault filter. Continuous reconfiguration is defined. An example is discussed with an explanation of transparent failure. Autonomous control is the scheme for controlling a continually reconfiguring system. The process of volunteering is also discussed. The virtual common memory is the common memory architecture used in the continuously reconfiguring system. Its physical implementation is explained. The fault filter is the method used to detect and deal with faulty processors. The different levels and the types of faults each handles are examined. 1 ref.

  12. Seismomagnetic response of a fault zone

    NASA Astrophysics Data System (ADS)

    Adushkin, V. V.; Loktev, D. N.; Spivak, A. A.

    2017-01-01

    Based on the results of instrumental observations of geomagnetic variations caused by the propagation of seismic waves through a fault zone, the dependences between the amplitudes of the induced seismomagnetic effect and seismic signal as a function of distance r to the midline of the fault are obtained. For the first time, it is shown that the amplitude of the seismomagnetic effect is maximal in the fault damage zone. The phenomenological model describing the generation of magnetic signals by seismic waves propagating through the crushed rock in the tectonic fault zone is suggested. It is assumed that geomagnetic variations are generated by the changes in the electrical conductivity of the fragmented rocks as a result of the deformation of the rock pieces contacts. The amplitudes of the geomagnetic variations calculated from the model agree with the instrumental observations.

  13. Transfer zones in listric normal fault systems

    NASA Astrophysics Data System (ADS)

    Bose, Shamik

    Listric normal faults are common in passive margin settings where sedimentary units are detached above weaker lithological units, such as evaporites or are driven by basal structural and stratigraphic discontinuities. The geometries and styles of faulting vary with the types of detachment and form landward and basinward dipping fault systems. Complex transfer zones therefore develop along the terminations of adjacent faults where deformation is accommodated by secondary faults, often below seismic resolution. The rollover geometry and secondary faults within the hanging wall of the major faults also vary with the styles of faulting and contribute to the complexity of the transfer zones. This study tries to understand the controlling factors for the formation of the different styles of listric normal faults and the different transfer zones formed within them, by using analog clay experimental models. Detailed analyses with respect to fault orientation, density and connectivity have been performed on the experiments in order to gather insights on the structural controls and the resulting geometries. A new high resolution 3D laser scanning technology has been introduced to scan the surfaces of the clay experiments for accurate measurements and 3D visualizations. Numerous examples from the Gulf of Mexico have been included to demonstrate and geometrically compare the observations in experiments and real structures. A salt cored convergent transfer zone from the South Timbalier Block 54, offshore Louisiana has been analyzed in detail to understand the evolutionary history of the region, which helps in deciphering the kinematic growth of similar structures in the Gulf of Mexico. The dissertation is divided into three chapters, written in a journal article format, that deal with three different aspects in understanding the listric normal fault systems and the transfer zones so formed. The first chapter involves clay experimental models to understand the fault patterns in

  14. Not-so-inactive fault in Oklahoma

    USGS Publications Warehouse

    Spall, Henry

    1986-01-01

    In connection with a search for geologically quiet areas for sitting large engineering ventures such as dams and nuclear power plants, geologists have recently started looking at the Meers fault in southwestern Oklahoma with an intense interest.

  15. Sea-Floor Spreading and Transform Faults

    ERIC Educational Resources Information Center

    Armstrong, Ronald E.; And Others

    1978-01-01

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

  16. Reset Tree-Based Optical Fault Detection

    PubMed Central

    Lee, Dong-Geon; Choi, Dooho; Seo, Jungtaek; Kim, Howon

    2013-01-01

    In this paper, we present a new reset tree-based scheme to protect cryptographic hardware against optical fault injection attacks. As one of the most powerful invasive attacks on cryptographic hardware, optical fault attacks cause semiconductors to misbehave by injecting high-energy light into a decapped integrated circuit. The contaminated result from the affected chip is then used to reveal secret information, such as a key, from the cryptographic hardware. Since the advent of such attacks, various countermeasures have been proposed. Although most of these countermeasures are strong, there is still the possibility of attack. In this paper, we present a novel optical fault detection scheme that utilizes the buffers on a circuit's reset signal tree as a fault detection sensor. To evaluate our proposal, we model radiation-induced currents into circuit components and perform a SPICE simulation. The proposed scheme is expected to be used as a supplemental security tool. PMID:23698267

  17. Fault-tolerant communication channel structures

    NASA Technical Reports Server (NTRS)

    Alkalai, Leon (Inventor); Chau, Savio N. (Inventor); Tai, Ann T. (Inventor)

    2006-01-01

    Systems and techniques for implementing fault-tolerant communication channels and features in communication systems. Selected commercial-off-the-shelf devices can be integrated in such systems to reduce the cost.

  18. Distributed Fault-Tolerant Control of Networked Uncertain Euler-Lagrange Systems Under Actuator Faults.

    PubMed

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

    2016-05-03

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

  19. Late Quaternary Faulting along the San Juan de los Planes Fault Zone, Baja California Sur, Mexico

    NASA Astrophysics Data System (ADS)

    Busch, M. M.; Coyan, J. A.; Arrowsmith, J.; Maloney, S. J.; Gutierrez, G.; Umhoefer, P. J.

    2007-12-01

    As a result of continued distributed deformation in the Gulf Extensional Province along an oblique-divergent plate margin, active normal faulting is well manifest in southeastern Baja California. By characterizing normal-fault related deformation along the San Juan de los Planes fault zone (SJPFZ) southwest of La Paz, Baja California Sur we contribute to understanding the patterns and rates of faulting along the southwest gulf-margin fault system. The geometry, history, and rate of faulting provide constraints on the relative significance of gulf-margin deformation as compared to axial system deformation. The SJPFZ is a major north-trending structure in the southern Baja margin along which we focused our field efforts. These investigations included: a detailed strip map of the active fault zone, including delineation of active scarp traces and geomorphic surfaces on the hanging wall and footwall; fault scarp profiles; analysis of bedrock structures to better understand how the pattern and rate of strain varied during the development of this fault zone; and a gravity survey across the San Juan de los Planes basin to determine basin geometry and fault behavior. The map covers a N-S swath from the Gulf of California in the north to San Antonio in the south, an area ~45km long and ~1-4km wide. Bedrock along the SJPFZ varies from Cretaceous Las Cruces Granite in the north to Cretaceous Buena Mujer Tonalite in the south and is scarred by shear zones and brittle faults. The active scarp-forming fault juxtaposes bedrock in the footwall against Late Quaternary sandstone-conglomerate. This ~20m wide zone is highly fractured bedrock infused with carbonate. The northern ~12km of the SJPFZ, trending 200°, preserves discontinuous scarps 1-2km long and 1-3m high in Quaternary units. The scarps are separated by stretches of bedrock embayed by hundreds of meters-wide tongues of Quaternary sandstone-conglomerate, implying low Quaternary slip rate. Further south, ~2 km north of the

  20. Porosity variations in and around normal fault zones: implications for fault seal and geomechanics

    NASA Astrophysics Data System (ADS)

    Healy, David; Neilson, Joyce; Farrell, Natalie; Timms, Nick; Wilson, Moyra

    2015-04-01

    Porosity forms the building blocks for permeability, exerts a significant influence on the acoustic response of rocks to elastic waves, and fundamentally influences rock strength. And yet, published studies of porosity around fault zones or in faulted rock are relatively rare, and are hugely dominated by those of fault zone permeability. We present new data from detailed studies of porosity variations around normal faults in sandstone and limestone. We have developed an integrated approach to porosity characterisation in faulted rock exploiting different techniques to understand variations in the data. From systematic samples taken across exposed normal faults in limestone (Malta) and sandstone (Scotland), we combine digital image analysis on thin sections (optical and electron microscopy), core plug analysis (He porosimetry) and mercury injection capillary pressures (MICP). Our sampling includes representative material from undeformed protoliths and fault rocks from the footwall and hanging wall. Fault-related porosity can produce anisotropic permeability with a 'fast' direction parallel to the slip vector in a sandstone-hosted normal fault. Undeformed sandstones in the same unit exhibit maximum permeability in a sub-horizontal direction parallel to lamination in dune-bedded sandstones. Fault-related deformation produces anisotropic pores and pore networks with long axes aligned sub-vertically and this controls the permeability anisotropy, even under confining pressures up to 100 MPa. Fault-related porosity also has interesting consequences for the elastic properties and velocity structure of normal fault zones. Relationships between texture, pore type and acoustic velocity have been well documented in undeformed limestone. We have extended this work to include the effects of faulting on carbonate textures, pore types and P- and S-wave velocities (Vp, Vs) using a suite of normal fault zones in Malta, with displacements ranging from 0.5 to 90 m. Our results show a

  1. Hydrologic Characterization Study at Wildcat Fault Zone

    NASA Astrophysics Data System (ADS)

    Karasaki, K.; Onishi, C. T.; Goto, J.; Moriya, T.; Ueta, K.; Kiho, K.

    2011-12-01

    A dedicated field site has been developed to further the understanding of, and to develop the characterization technology for, fault zone hydrology in the hills east of Berkeley, California across the Wildcat Fault. The Wildcat is believed to be a strike-slip fault and a member of the Hayward Fault System, with over 10 km of displacement. So far, several ~2-4-m deep trenches were cut, a number of surface-based geophysical surveys were conducted, and four ~150-m deep fully cored boreholes were drilled at the site; one on the east side and two on the west side of the suspected fault trace. The inclined fourth hole was drilled to penetrate the Wildcat. Geologic analysis results from these trenches and boreholes indicated that the geology was not always what was expected: while confirming some earlier, published conclusions about Wildcat, they have also led to some unexpected findings. The lithology at the Wildcat Fault area mainly consists of chert, shale, silt and sandstone, extensively sheared and fractured with gouge and cataclasite zones observed at several depths. Wildcat near the field site appears to consist of multiple fault planes with the major fault planes filled with unconsolidated pulverized rock instead of clay gouge. The pressure and temperature distributions indicate a downward hydraulic gradient and a relatively large geothermal gradient. Various types of borehole logging were conducted but there were no obvious correlations between boreholes or to hydrologic properties. Using the three other boreholes as observation wells, hydrologic cross-hole pumping tests were conducted in the fourth borehole. The hydraulic test data suggest the dual properties of the hydrologic structure of the fault zone: high permeability along the plane and low permeability across it, and the fault planes may be compartmentalizing aquifers. No correlation was found between fracture frequency and flow. Long term pressure monitoring over multiple seasons was shown to be very

  2. Strong ground motions generated by earthquakes on creeping faults

    USGS Publications Warehouse

    Harris, Ruth A.; Abrahamson, Norman A.

    2014-01-01

    A tenet of earthquake science is that faults are locked in position until they abruptly slip during the sudden strain-relieving events that are earthquakes. Whereas it is expected that locked faults when they finally do slip will produce noticeable ground shaking, what is uncertain is how the ground shakes during earthquakes on creeping faults. Creeping faults are rare throughout much of the Earth's continental crust, but there is a group of them in the San Andreas fault system. Here we evaluate the strongest ground motions from the largest well-recorded earthquakes on creeping faults. We find that the peak ground motions generated by the creeping fault earthquakes are similar to the peak ground motions generated by earthquakes on locked faults. Our findings imply that buildings near creeping faults need to be designed to withstand the same level of shaking as those constructed near locked faults.

  3. Polychlorinated biphenyls in selected sites in Pasig River and Laguna Lake in the Philippines before and after a big flood event investigated under the UNU East Asia Regional POPs monitoring project.

    PubMed

    Santiago, Evangeline C; Rivas, Fritzi

    2012-08-01

    This paper reports the results of the 2009 United Nations University (UNU) East Asia Regional Monitoring of the Coastal Hydrosphere Project implemented in the Philippines. The monitoring activity focused on the concentrations of 16 specific congeners of Polychlorinated Biphenyls in selected sites in Pasig River and Laguna Lake for two sampling periods in August and in November, 2009. The results show that the total concentrations of PCBs detected in the sampling sites in August increased during the November sampling from 0.9-12.2 to 6.1-32 ng/L in Pasig River and from 0.1-0.9 to 2.9-10.8 ng/L in Laguna Lake. The increase in PCB concentrations on second sampling is attributed to the increase in contaminated sediments in the river sites and to the overflow of contaminated water in the lake sites; both of which could have been caused by the flooding event that occurred in September 2009.

  4. HVAC Fault Detection and Diagnosis Toolkit

    SciTech Connect

    Haves, Philip; Xu, Peng; Kim, Moosung

    2004-12-31

    This toolkit supports component-level model-based fault detection methods in commercial building HVAC systems. The toolbox consists of five basic modules: a parameter estimator for model calibration, a preprocessor, an AHU model simulator, a steady-state detector, and a comparator. Each of these modules and the fuzzy logic rules for fault diagnosis are described in detail. The toolbox is written in C++ and also invokes the SPARK simulation program.

  5. Geometric incompatibility in a fault system.

    PubMed Central

    Gabrielov, A; Keilis-Borok, V; Jackson, D D

    1996-01-01

    Interdependence between geometry of a fault system, its kinematics, and seismicity is investigated. Quantitative measure is introduced for inconsistency between a fixed configuration of faults and the slip rates on each fault. This measure, named geometric incompatibility (G), depicts summarily the instability near the fault junctions: their divergence or convergence ("unlocking" or "locking up") and accumulation of stress and deformations. Accordingly, the changes in G are connected with dynamics of seismicity. Apart from geometric incompatibility, we consider deviation K from well-known Saint Venant condition of kinematic compatibility. This deviation depicts summarily unaccounted stress and strain accumulation in the region and/or internal inconsistencies in a reconstruction of block- and fault system (its geometry and movements). The estimates of G and K provide a useful tool for bringing together the data on different types of movement in a fault system. An analog of Stokes formula is found that allows determination of the total values of G and K in a region from the data on its boundary. The phenomenon of geometric incompatibility implies that nucleation of strong earthquakes is to large extent controlled by processes near fault junctions. The junctions that have been locked up may act as transient asperities, and unlocked junctions may act as transient weakest links. Tentative estimates of K and G are made for each end of the Big Bend of the San Andreas fault system in Southern California. Recent strong earthquakes Landers (1992, M = 7.3) and Northridge (1994, M = 6.7) both reduced K but had opposite impact on G: Landers unlocked the area, whereas Northridge locked it up again. Images Fig. 1 Fig. 2 PMID:11607673

  6. Using Relocatable Bitstreams For Fault Tolerance

    DTIC Science & Technology

    2007-03-01

    fault tolerant, increasing their dependability and availability, by allowing an FPGA to restore its functionality after a fault has been detected ...device to be programmed, thus providing direct support for dynamic reconfiguration [GLS99]. All action in JBits must be specified in the source code ... FPGA families, including the Virtex-II Pro, and provides a router based on JHDLBits, an open source project that connects JHDL and JBits. JBits 3.0

  7. Stacking fault energy in some single crystals

    NASA Astrophysics Data System (ADS)

    Vora, Aditya M.

    2012-06-01

    The stacking fault energy of single crystals has been reported using the peak shift method. Presently studied all single crystals are grown by using a direct vapor transport (DVT) technique in the laboratory. The structural characterizations of these crystals are made by XRD. Considerable variations are shown in deformation (α) and growth (β) probabilities in single crystals due to off-stoichiometry, which possesses the stacking fault in the single crystal.

  8. GN and C Fault Protection Fundamentals

    NASA Technical Reports Server (NTRS)

    Rasmussen, Robert D.

    2008-01-01

    This is a companion presentation for a paper by the same name for the same conference. The objective of this paper is to shed some light on the fundamentals of fault tolerant design for GN&C. The common heritage of ideas behind both faulted and normal operation is explored, as is the increasingly indistinct line between these realms in complex missions. Techniques in common practice are then evaluated in this light to suggest a better direction for future efforts.

  9. A Primer on Architectural Level Fault Tolerance

    NASA Technical Reports Server (NTRS)

    Butler, Ricky W.

    2008-01-01

    This paper introduces the fundamental concepts of fault tolerant computing. Key topics covered are voting, fault detection, clock synchronization, Byzantine Agreement, diagnosis, and reliability analysis. Low level mechanisms such as Hamming codes or low level communications protocols are not covered. The paper is tutorial in nature and does not cover any topic in detail. The focus is on rationale and approach rather than detailed exposition.

  10. A survey of fault diagnosis technology

    NASA Technical Reports Server (NTRS)

    Riedesel, Joel

    1989-01-01

    Existing techniques and methodologies for fault diagnosis are surveyed. The techniques run the gamut from theoretical artificial intelligence work to conventional software engineering applications. They are shown to define a spectrum of implementation alternatives where tradeoffs determine their position on the spectrum. Various tradeoffs include execution time limitations and memory requirements of the algorithms as well as their effectiveness in addressing the fault diagnosis problem.

  11. Limiting Maximum Magnitude by Fault Dimensions (Invited)

    NASA Astrophysics Data System (ADS)

    Stirling, M. W.

    2010-12-01

    A standard practise of seismic hazard modeling is to combine fault and background seismicity sources to produce a multidisciplinary source model for a region. Background sources are typically modeled with a Gutenberg-Richter magnitude-frequency distribution developed from historical seismicity catalogs, and fault sources are typically modeled with earthquakes that are limited in size by the mapped fault rupture dimensions. The combined source model typically exhibits a Gutenberg-Richter-like distribution due to there being many short faults relative to the number of longer faults. The assumption that earthquakes are limited by the mapped fault dimensions therefore appears to be consistent with the Gutenberg-Richter relationship, one of the fundamental laws of seismology. Recent studies of magnitude-frequency distributions for California and New Zealand have highlighted an excess of fault-derived earthquakes relative to the log-linear extrapolation of the Gutenberg-Richter relationship from the smaller magnitudes (known as the “bulge”). Relaxing the requirement of maximum magnitude being limited by fault dimensions is a possible solution for removing the “bulge” to produce a perfectly log-linear Gutenberg-Richter distribution. An alternative perspective is that the “bulge” does not represent a significant departure from a Gutenberg-Richter distribution, and may simply be an artefact of a small earthquake dataset relative to the more plentiful data at the smaller magnitudes. In other words the uncertainty bounds of the magnitude-frequency distribution at the moderate-to-large magnitudes may be far greater than the size of the “bulge”.

  12. The San Andreas Fault System, California, USA

    USGS Publications Warehouse

    Brown, R.D.; Wallace, R.E.; Hill, D.P.

    1992-01-01

    Geologists, seismologists, and geophysicists have intensively studied the San Andreas fault system for the past 20 to 30 years. Their goals were to learn more about damaging earthquakes, the behavior of major stirke-slip faults, and methods of reducing earthquake hazards in populated areas. Field geologic investigations, seismic networks, post-earthquake studies, precision geodetic surveys, and reflection and refraction seismic surveys are among the methods used to decipher the history, geometry, and mechanics of the system. -from Authors

  13. Deformation Monitoring of AN Active Fault

    NASA Astrophysics Data System (ADS)

    Ostapchuk, A.

    2015-12-01

    The discovery of low frequency earthquakes, slow slip events and other deformation phenomena, new for geophysics, change our understanding of how the energy accumulated in the Earth's crust do release. The new geophysical data make one revise the underlying mechanism of geomechanical processes taking place in fault zones. Conditions for generating different slip modes are still unclear. The most vital question is whether a certain slip mode is intrinsic for a fault or may be controlled by external factors. This work presents the results of two and a half year deformation monitoring of a discontinuity in the zone of the Main Sayanskiy Fault. Main Sayanskiy Fault is right-lateral strike-slip fault. Observations were performed in the tunnel of Talaya seismic station (TLY), Irkutsk region, Russia. Measurements were carried out 70 m away from the entrance of the tunnel, the thickness of overlying rock was about 30 m. Inductive sensors of displacement were mounted at the both sides of a discontinuity, which recorded three components of relative fault side displacement with the accuracy of 0.2 mcm. Temperature variation inside the tunnel didn't exceed 0.5oC during the all period of observations. Important information about deformation properties of an active fault was obtained. A pronounced seasonality of deformation characteristics of discontinuity is observed in the investigated segment of rock. A great number of slow slip events with durations from several hours to several weeks were registered. Besides that alterations of fault deformation characteristics before the megathrust earthquake M9.0 Tohoku Oki 11 March 2011 and reaction to the event itself were detected. The work was supported by the Russian Science Foundation (grant no. 14-17-00719).

  14. Effect of distributed inelastic deformation on fault slip profiles and fault interaction under mid-crustal conditions

    NASA Astrophysics Data System (ADS)

    Nevitt, J. M.; Pollard, D. D.

    2015-12-01

    Under mid-crustal conditions, faults commonly are associated with distributed inelastic deformation (i.e., ductile fabrics). The effect of such inelastic deformation on fault slip profiles and fault interaction remains poorly understood, though it likely plays a significant role in the earthquake cycle. We have investigated meter-scale strike-slip faults exhumed from ~10 km depth in the Lake Edison granodiorite (Sierra Nevada, CA). These faults are characterized by slip-to-length ratios and slip gradients near fault tips that greatly exceed what is measured for faults in the brittle upper crust, or produced by linear elastic models. Using Abaqus, we construct elastoplastic finite element models to evaluate the impact of off-fault plasticity on the resulting slip profiles for both continuous and discontinuous faults. Elastoplastic models show that plastic strain near fault tips effectively lengthens faults, allowing for greater overall slip and increased slip gradients near fault tips. In the field, regions adjacent to fault tips contain mylonitized granodiorite and ductilely sheared dikes and schlieren, consistent with the model results. In addition, distributed plastic strain facilitates slip transfer between echelon fault segments, particularly for contractional step geometries. Relative to an isolated fault, fault segments adjacent to contractional steps are asymmetric, with the maximum slip shifted in the direction of the step. Immediately adjacent to the contractional step, fault slip is significantly reduced because shear offset is accommodated by distributed plastic shearing within the step, rather than by discrete slip on the faults. Although slip is locally reduced on each fault segment directly adjacent to a contractional step, overall slip transfer between discontinuous fault segments is most efficient for this step geometry. That is, faults segmented by contractional steps produce greater maximum slip than do those separated by extensional steps

  15. Optical methods in fault dynamics

    NASA Astrophysics Data System (ADS)

    Uenishi, K.; Rossmanith, H. P.

    2003-10-01

    The Rayleigh pulse interaction with a pre-stressed, partially contacting interface between similar and dissimilar materials is investigated experimentally as well as numerically. This study is intended to obtain an improved understanding of the interface (fault) dynamics during the earthquake rupture process. Using dynamic photoelasticity in conjunction with high-speed cinematography, snapshots of time-dependent isochromatic fringe patterns associated with Rayleigh pulse-interface interaction are experimentally recorded. It is shown that interface slip (instability) can be triggered dynamically by a pulse which propagates along the interface at the Rayleigh wave speed. For the numerical investigation, the finite difference wave simulator SWIFD is used for solving the problem under different combinations of contacting materials. The effect of acoustic impedance ratio of the two contacting materials on the wave patterns is discussed. The results indicate that upon interface rupture, Mach (head) waves, which carry a relatively large amount of energy in a concentrated form, can be generated and propagated from the interface contact region (asperity) into the acoustically softer material. Such Mach waves can cause severe damage onto a particular region inside an adjacent acoustically softer area. This type of damage concentration might be a possible reason for the generation of the "damage belt" in Kobe, Japan, on the occasion of the 1995 Hyogo-ken Nanbu (Kobe) Earthquake.

  16. Fault-tolerant PACS server

    NASA Astrophysics Data System (ADS)

    Cao, Fei; Liu, Brent J.; Huang, H. K.; Zhou, Michael Z.; Zhang, Jianguo; Zhang, X. C.; Mogel, Greg T.

    2002-05-01

    Failure of a PACS archive server could cripple an entire PACS operation. Last year we demonstrated that it was possible to design a fault-tolerant (FT) server with 99.999% uptime. The FT design was based on a triple modular redundancy with a simple majority vote to automatically detect and mask a faulty module. The purpose of this presentation is to report on its continuous developments in integrating with external mass storage devices, and to delineate laboratory failover experiments. An FT PACS Simulator with generic PACS software has been used in the experiment. To simulate a PACS clinical operation, image examinations are transmitted continuously from the modality simulator to the DICOM gateway and then to the FT PACS server and workstations. The hardware failures in network, FT server module, disk, RAID, and DLT are manually induced to observe the failover recovery of the FT PACS to resume its normal data flow. We then test and evaluate the FT PACS server in its reliability, functionality, and performance.

  17. Evaluation of Cepstrum Algorithm with Impact Seeded Fault Data of Helicopter Oil Cooler Fan Bearings and Machine Fault Simulator Data

    DTIC Science & Technology

    2013-02-01

    seeded fault without gearbox and magnet load...Figure B-1. Ball seeded fault bearings with and without gearbox and magnet load for level 1. ..18 Figure B-2. Ball seeded fault bearings with and...without gearbox and magnet load for level 3. ..19 Figure B-3. Ball seeded fault bearings with and without gearbox and magnet load for level 5. ..20

  18. Development of Fault Models for Hybrid Fault Detection and Diagnostics Algorithm: October 1, 2014 -- May 5, 2015

    SciTech Connect

    Cheung, Howard; Braun, James E.

    2015-12-31

    This report describes models of building faults created for OpenStudio to support the ongoing development of fault detection and diagnostic (FDD) algorithms at the National Renewable Energy Laboratory. Building faults are operating abnormalities that degrade building performance, such as using more energy than normal operation, failing to maintain building temperatures according to the thermostat set points, etc. Models of building faults in OpenStudio can be used to estimate fault impacts on building performance and to develop and evaluate FDD algorithms. The aim of the project is to develop fault models of typical heating, ventilating and air conditioning (HVAC) equipment in the United States, and the fault models in this report are grouped as control faults, sensor faults, packaged and split air conditioner faults, water-cooled chiller faults, and other uncategorized faults. The control fault models simulate impacts of inappropriate thermostat control schemes such as an incorrect thermostat set point in unoccupied hours and manual changes of thermostat set point due to extreme outside temperature. Sensor fault models focus on the modeling of sensor biases including economizer relative humidity sensor bias, supply air temperature sensor bias, and water circuit temperature sensor bias. Packaged and split air conditioner fault models simulate refrigerant undercharging, condenser fouling, condenser fan motor efficiency degradation, non-condensable entrainment in refrigerant, and liquid line restriction. Other fault models that are uncategorized include duct fouling, excessive infiltration into the building, and blower and pump motor degradation.

  19. Software fault tolerance in computer operating systems

    NASA Technical Reports Server (NTRS)

    Iyer, Ravishankar K.; Lee, Inhwan

    1994-01-01

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

  20. Diagnosing faults in autonomous robot plan execution

    NASA Technical Reports Server (NTRS)

    Lam, Raymond K.; Doshi, Rajkumar S.; Atkinson, David J.; Lawson, Denise M.

    1989-01-01

    A major requirement for an autonomous robot is the capability to diagnose faults during plan execution in an uncertain environment. Many diagnostic researches concentrate only on hardware failures within an autonomous robot. Taking a different approach, the implementation of a Telerobot Diagnostic System that addresses, in addition to the hardware failures, failures caused by unexpected event changes in the environment or failures due to plan errors, is described. One feature of the system is the utilization of task-plan knowledge and context information to deduce fault symptoms. This forward deduction provides valuable information on past activities and the current expectations of a robotic event, both of which can guide the plan-execution inference process. The inference process adopts a model-based technique to recreate the plan-execution process and to confirm fault-source hypotheses. This technique allows the system to diagnose multiple faults due to either unexpected plan failures or hardware errors. This research initiates a major effort to investigate relationships between hardware faults and plan errors, relationships which were not addressed in the past. The results of this research will provide a clear understanding of how to generate a better task planner for an autonomous robot and how to recover the robot from faults in a critical environment.